Thuy-Chung Kieu-Le

Quoc-Thinh Thuong

Tran-Nguyen-Sang Truong

Thi-Minh-Tam Le

Quoc-Viet Tran

Emilie Strady
email: emilie.strady@ird.fr

Tien River

Ham Luong

River Co

Baseline concentration of microplastics in surface water and sediment of the northern branches of the Mekong River Delta, Vietnam

The Mekong River Delta in Vietnam, is conce rned by numerous micropl astic-related issues such as a lack of waste wate r tre atment facilities and mismanage ment of plastic waste released from agriculture, aquacult ure and related activities. This study ai med to examine the presence of microplastics in surface water and sedi ment by collecting samples from siX sites along the Tien River and its distributaries in February 2019. The results showed that the average concentration of microplastics over the entire area was 53.8 ± 140.7 items m -3 in surface water and 6.0 ± 2.0 items g -1 dried wei ght in sedi ment, wi th a pre domi nance of microplastic fibres rat he r t han fragments, respectively 85 % and 98 % in surface water and sediment. In t he main flow of surface wate r, t he concentration of microplastics was stable; however, in t he sedi ment, micropl astic concent ration was affected by the high dynamic flow regime rather than the sources where microplastics are released.

Introduction

Since the first evidence of microplastic presence in sediment samples collected from beaches around Plymouth City, England (Thompson et al., 2004), microplasticsplastic particles <5 mm in size (GESAMP, 2019)and the pollution caused by them have become a ubiquitous environmental issue. Over the last decade, knowledge on microplastic pollution, i.e., abundance in different environments, sources, transport, and ecotoXicity, has been remarkably elucidated. Microplastics have been found across the globe at different levels a nd in most of different environmental compartments as water, sediment, atmospheric fallout and biota [START_REF] Yusuf | Updated review on microplastics in water, their o ccu rrence, detection, m easurem ent, environm ental pollution, an d the need for regu lato ry standards[END_REF]Perumal and Muthuramalingam, 2022;[START_REF] Yuan | Occurrence and h u m an exposure risks of atm ospheric microplastics : a review[END_REF][START_REF] Ugwu | Microplastics in m arine b io ta: a review[END_REF]Kumar et al., 2021a). Compared to other regions, Asia countries, the biggest contributors to marine plastic wastes due to mainly waste mismanagement (Jambeck et al., 2015;[START_REF] Meijer | More th an 1000 rivers account for 80% of global riverine plastic emissions into the ocean[END_REF] are encountering the most vulnerable abundance levels of microplastics (Kumar et al., 2021a;[START_REF] Yang | Ch em o sphere a co m p arative review of microplastics in lake systems from different countries and regions[END_REF]. The presence of microplastics in the environments is related to local development and economic structures and mainly originated from the release of treated or untreated waste water and landfill leachate to the environment, the improper treatment of plastic wastes, and from other activities such as aquaculture, agriculture, and shipping (Xiang et al., 2022;[START_REF] Yang | Ch em o sphere a co m p arative review of microplastics in lake systems from different countries and regions[END_REF]. Microplastics in the water can deposit to the bottom sediments or can be transported over a short or long distance, ingested by the organisms. The bioaccumulation and biomagnification of microplastics through the food chain have been alarmed in various research. The potential toXicity of microplastics could come from the additives added during the production of plastics or adsorbed pollutants, i.e. organic pollutants and heavy metals, on microplastic surface [START_REF] Nam | Towards understanding the im pact of plastics on freshwater and marine m icro algae: a review of the mechanisms an d toXicity endpoints[END_REF]Xiang et al., 2022). The coexistence of microplastics and these pollutants may lead to a more vulnerable threats to hu man health and the environment at two folds: (i) a higher accumulation of the pollutants in microplastics than in the ambience up to two to three orders of magnitude and (ii) a higher level of toXicity of the combination of microplastics and some pollutants compared to the toXicity of individual pollutants [START_REF] Verla | Microplastic-toXic chem ical in teractio n: a review study on quantified levels, m echanism and im plication[END_REF]Campanale et al., 2020b;Xiang et al., 2022). This interaction could be affected by the characteristics of microplastics, i.e., type, size, aging degree, etc., and of the pollutants and the conditions of the environment [START_REF] Nam | Towards understanding the im pact of plastics on freshwater and marine m icro algae: a review of the mechanisms an d toXicity endpoints[END_REF]Xiang et al., 2022).

primarily between August and November, when a high volume of water from upstream of the Mekong River flows to the delta, leading to a change in the livelihood of local people. More specifically, the Tien River system is flowing through urban dense cities (e.g., Cao Lanh, My Tho, Cho Lach, and Ben Tre), agriculture area (rice, fruit), industrial zones and aquaculture area (shrimp). The siX sampling sites were located along the Tien River system distributaries: Cao Lanh, My Tho, Cho Lach, Ben Tre, Vinh Long, and Tra Vinh (Fig. 1). Among the sampling sites, the Cao Lanh site was in the Cai Sao Thuong River, a secondary tributary of the Tien River; it flows through the urban area of Cao Lanh City. Other sites were located in primary tributaries of the Tien River system with My Tho on the Tien River; Cho Lach and Ben Tre on the Ham Luong River; and Vinh Long and Tra Vinh on the Co Chien River (Table 1).

The solid waste in MRD was estimated of 5852 and 3577 tons day -1 , with collection rates of 49 % and 88 %, in rural and urban areas, respectively [START_REF] Monre | Report on the State of the National Environm ent 2019: Managem ent of Household Solid Waste[END_REF]. In many rural areas, household waste is buried in open and unsanitary landfills, burnt, or discarded into the environment [START_REF] Nguyen | Solid waste m anagem ent in Mekong Delta[END_REF]. Plastic waste from agricultural activities (e.g. plastic bottles and bags containing pesticides, herbicides, and fertilizers, [START_REF] Le | Plastic Wastes Pose Threats on Vietnam's Environment[END_REF] and aquaculture activities (e.g. fishing equipment such as nets, lines, and plastic floats, and plastic sheets used as the bottom layer of shrimp ponds) are thrown in the aquatic environment.

Sampling

Sampling campaign was carried out in October 2018. At each site of the siX sites, surface water and sediment samples were collected near the low tide. Duplicate surface water samples were collected in the middle of the river, using a plankton net 300 μm mesh size and 50 cm diameter, during 5 min. At each sampling, the net was placed perpendicularly to the current and towed by a local boat to ensure the current speed entering the net at about 0.5 m s -1 . The volume of the collected water was measured using an Oceanics flowmeter attached to the plankton net, after which the net was rinsed from the outside, and the sample was collected in a 500 mL glass bottle.

Sediment samples were collected using an Ekman grab sampler in the intertidal zone. At each sampling site, two to four sub-samples were collected and homogenised into a single sample. ApproXimately 1 kg of sediment was collected at each site and kept in a Ziploc plastic bag. After being transported to the laboratory, the samples were stored in a 4 • C cooler for later analysis.

Laboratory analysis

Analysis of surface water samples was carried out based on the five step treatment protocol proposed by [START_REF] Strady | Baseline assessment of m icroplastic concentrations in m arin e and freshwater environm ents of a d evelo p in g Southeast Asian country, Viet Nam[END_REF]: (1) sample preparation: The samples were processed through a 1 mm mesh size sieve to discard all larger fractions; suspected microplastics smaller than 5 mm were kept and stored in Petri dishes. (2) Sample digestion: To reduce the high density of interfering particles such as leaves, wood, sand, and minerals, a two-step sample digestion was conducted comprising of digestion of interfering matter, and density separation. For each 350 mL sample, 1 g of sodium dodecyl sulphate (Merck®) was added to the bottles and heated at 55 • C for 24 h. Next, 1 mL of biozyme SE (protease and amylase, Spinnrad®) and 1 mL of biozyme F (lipase, Spinnrad®) were added to the samples and heated at 40 • C for 48 h. The samples were subsequently oXidised using 15 mL of H2O2 (30 %, Merck®) at 40 • C for a further 48 h. After five days of digestion, the treated samples were sifted through a 250 μm mesh size sieve to remove all fractions smaller than 250 μm in size. (3) Density separation: The Microplastics in the environment exist in different forms, such as microbeads, pellets, films, foams, fragments, and fibres. They are usually divided into primary or secondary microplastics based on their source [START_REF] Lusher | Microplastics in fisheries and aq u acu ltu re[END_REF]. Primary microplastics are often pellets, microsized spherical plastic particles added to personal care products, microbeads, or multi-faceted plastic particles used as input materials in the plastic industry. Secondary microplastics include films, foams, fragments, and fibres a nd are generated from the fragmentation of larger plastics or from the protective coating of ships and boats. This is primarily caused by weather agents such as ultraviolet radiation, or other mechanical, chemical, a nd biological degradation processes. Fibres are the most dominant form and are primarily released from untreated domestic wastewater through the laundries of synthetic clothes and from industrial wastewater generated by the textile a nd apparel industries [START_REF] Bui | Microplastics pollutio n in wastewater: characteristics, occurrence and removal technologies[END_REF][START_REF] Auta | Distrib u tio n and im portance of microplastics in the m arine environm entA review of the sources, fate, effects, and potential solutions[END_REF][START_REF] Duis | Microplastics in the aquatic and terrestrial environm ent: sources (with a specific focus on personal care products), fate an d effects[END_REF]. Secondary microplastics are estimated to occupy the majority of microplastics in the environment and become more difficult to tackle because of the large amount of macroplastics entering the oceans every year [START_REF] Meijer | More th an 1000 rivers account for 80% of global riverine plastic emissions into the ocean[END_REF]. The role of coastal zones and rivers as the main input of plastic debris to oceans is now recognised [START_REF] Meijer | More th an 1000 rivers account for 80% of global riverine plastic emissions into the ocean[END_REF][START_REF] Lebreton | River plastic emissions to the world 's oceans[END_REF]. It was estimated that between 1.15 and 2.41 million tons of plastic annually enters the oceans from global river systems, of which the top 20 contributing rivers were from Asia (67 %). The Mekong River, which is the world's second richest river basin in terms of biodiversity (World Wide Fund for Wildlife, 2016) and is considered the lifeline for the entire basin of five Southeast Asian developing countries, was ranked at 11 out of 20 [START_REF] Lebreton | River plastic emissions to the world 's oceans[END_REF].

In 2015, the mismanagement of solid waste brought Vietnam in the list of the top countries emitting most plastics to the global oceans (Jambeck et al., 2015). Microplastics were measured in various aquatic environments including rivers, lakes, bays, and beaches in Vietnam, indicating the link of microplastic concentration to the plastic-related anthropogenic activities of the surrounding areas [START_REF] Doan | Microplastic in atm ospheric fallouts of a developing southeast asian m egacity under tro p ical clim ate[END_REF][START_REF] Lahens | Macroplastic and m icroplastic contam ination assessm ent of a tro p ical river (Saigon River, Vietnam ) transversed by a developing m egacity[END_REF][START_REF] Strady | Tem poral dynam ic of anthropogenic fibers in a tropical river-estuarine system[END_REF][START_REF] Strady | Baseline assessment of m icroplastic concentrations in m arin e and freshwater environm ents of a d evelo p in g Southeast Asian country, Viet Nam[END_REF][START_REF] Nguyen | Characteristics of microplastics in shoreline sedim ents from a tropical and urbanized beach (Da Nang, Vietnam )[END_REF]. Located downstream of the Mekong River, the Mekong River Delta (MRD), hosting 17.3 million inhabitants, contributes to more than half of the country's production of rice, fruits, a nd aquaculture products (GSO, 2020). The MRD is especially vulnerable to climate change, facing issues such as sea level rise, salinity intrusion, and flooding, and its aquatic environment is already contaminated by various pollutants such as trace metals and organic pollutants originated from aquaculture, agriculture, craft villages, households, a nd industrial activities (ADB, 2015;[START_REF] Le | An in tegrated ecosystem incorporating renewable energy leading to pollution reduction for sustainable developm ent of craft villages in rural area: a case study at sedge m ats village in Mekong Delta, Vietnam[END_REF]MDP-team, 2013;[START_REF] Monre | Report on the State of the National Environm ent 2019: Managem ent of Household Solid Waste[END_REF][START_REF] Monre | National Rural Environm ent Report[END_REF][START_REF] Pham | Pesticide m anagem ent and their resid u es in sedim ents and surface and drinking water in the Mekong Delta, V ietnam[END_REF][START_REF] Strady | Spatial variation and risk assessm ent of trace m etals in water and sedim ent of the Mekong Delta[END_REF]. So far, little is known about the microplastic pollution status in the Mekong Delta. The presence of both dense urban areas (with numerous cities above 100,000 inhabitants) and rural areas dominated by agriculture and aquaculture activities raises the hypothesis of contrasted microplastic concentrations along the river watershed. This study aims thus to evaluate the microplastic contamination level in surface waters a nd intertidal riverine sediments of this environment a nd discuss their distribution relative to local activities and features. The Tien River system, the Mekong's northern branch, was selected for collecting surface water and sediment to represent the different anthropogenic activities and pressure observed at the scale of the MRD.

Materials and methods

Study area

The northern branch of the Mekong River Delta (40,000 km 2 , the largest delta in Vietnam) has a total length of 230 km and flows to the East China Sea through three main distributaries: Tien River, Ham Luong River, a nd Co Chien River. In the MRD, the climate is tropical with two distinct seasons: the rainy season from May to November, and the dry season from December to April, with flooding occurring overflow was performed using filtered NaCl solution (d = 1.18 ± 0.02 g mL -1 ) until all plastic were retrieved. ( 4) Sample filtration: The supernatant of the overflow solution was then filtered through GF/A filters (1.6 μm porosity, Whatman®) using a glassware filtration unit. After that, the filters were kept separately in sterile Petri dishes until the observation step (5), which is discussed in Section 2.4.

The analytical procedure for sediment samples was the same as that used for treating surface water samples, except for some differences in the preparation step and digestion step. Prior analysis, for each site, the moisture content of the sediments was firstly determined by drying approXimately 20 g of sediment sample at 55 • C during 72 h until the sample weight became constant. Then, duplicate samples were analysed for microplastics. For each replicate, after a thorough homogenisation of the sample, a known mass of moist sediment equivalent to 10 g of dry 2 2 sediment was placed in a 250 mL beaker and digested with 30 % H O at 40 • C. The volume of the digestion solution was in the range of 20-25 mL and was gradually added until the sediment was completely digested. The oXidised solution was then sifted through a 250 μm mesh size sieve and separated by NaCl solution before filtration.

Observation

Microplastics observation and evaluation of their size, colour, nature, and shape was carried out, using a Leica stereoscope S6D (0.5× to 80×) coupled with LAS software®. In this study, the criterion proposed by [START_REF] Nor´en | Small plastic particles in Coastal Swedish waters[END_REF] and used by [START_REF] Strady | Baseline assessment of m icroplastic concentrations in m arin e and freshwater environm ents of a d evelo p in g Southeast Asian country, Viet Nam[END_REF] were followed to identify the microplastic particles in terms of appearance and internal structure among other materials such as fine and coarse sand, phytoplankton, and zooplankton. For the purpose of this study, the microplastic fibres were defined as elongated lines with three-dimensional bending and an equal thickness throughout their entire length. In contrast, microplastic fragments were defined in one of three ways. Firstly, as irregular hard particles that appeared to be broken from larger pieces of macroplastics. Secondly, as flat flexible particles with smooth or angular edges, or finally, as near spherical or granular particles which deform readily u nder pressure and can be partly elastic [START_REF] Nor´en | Small plastic particles in Coastal Swedish waters[END_REF]. All microplastic fibres and fragments had an absence of visible cellular or organic structures and exhibited a clear and homogeneous colour throughout (Fig. 2). Based on the GESAMP recommendations, a minimum length of 300 μm for microplastic fibres and a minimum surface area size of 45,000 μm 2 for microplastic fragments were chosen to identify each during the visual observation (GESAMP, 2019).

Quality control

Several quality control steps were taken during the sample treatment and observation process to prevent contamination from outside microplastics a nd control the data quality. Work areas were cleaned with alcohol and filtered tap water at the beginning of the procedure. Laboratory operators wore cotton laboratory coats, masks, a nd sterile latex gloves. All glassware was washed with filtered tap water (GF/A filters; 1.6 μm porosity, Whatman®) and covered with aluminium foil before use. Further, three control steps based on those used by [START_REF] Strady | Baseline assessment of m icroplastic concentrations in m arin e and freshwater environm ents of a d evelo p in g Southeast Asian country, Viet Nam[END_REF] were implemented. These were: positive extraction control (PEC), digestion atmospheric control (DAC), and observation atmospheric control (OAC). The PEC was conducted by adding 10 pieces of yellow polyethylene microplastics (CARAT®) into the samples after the sample preparation step. This control step aimed to evaluate the recovery efficiency of the added microplastics after the digestion step in the laboratory. The DAC a nd OAC were then conducted to check the contamination of microplastics by placing a virgin GF/A filter close to the sample over the course of the digestion step and observation step, respectively. The PEC recovery efficiency (n = 12) was 98 %. The DAC (n = 24) and OAC (n = 24) evidenced an average quantity of 4.4 and 0.3 fibres per filter, respectively. No correction was applied to the results based on the PEC, DAC, or OAC values.

Fourier transform infrared spectrometry (FTIR)

To prepare the tested particles for the FTIR-ATR tests, we wetted the shank of a sewing needle with filtered tap water and carefully touched it to the particle on the filter before transferring it to the microscopic slide. This step was performed under the restriction of having a ventilation fan in the testing area. The chemical composition of the microplastics was analysed by Fourier transform infrared spectrometry using an FTIR-ATR iS50 Thermo Fisher Scientific®. In total, 87 suspected particles (51 fragments and eight fibres in surface waters and seven fragments and 21 fibres in sediments) were tested. They were chosen according to different criteria, such as their possibility of being easily picked up and analysed by FTIR-ATR; their representativeness of the sample selection as a whole; and our uncertainty regarding their composition, as FTIR-ATR was sometimes necessary for particles which could not be classified through only visual observation. The composition of the tested particles was confirmed when the match between the tested and reference spectra was over 70 %.

Analysis

The concentrations of microplastics were calculated in units of items m -3 for surface water and items g -1 dry weight (d.w.) of sediment. The concentrations of fragments and fibres and their part of the total microplastics at each sampling site were also determined. Statistical Kruskal Wallis tests were conducted using XLSTAT® to compare the size of microplastics in surface water and sediment.

Results

Abundance of microplastics

In surface water, the average concentration of microplastics across the entire river system was 53.8 ± 140.7 items m -3 . Microplastics were observed in both replicates at all the sampling sites (Table 2a). Among the sampling sites, microplastic concentrations for both fibres a nd fragments were always observed to be lowest at Ben Tre and highest at Cao Lanh, with concentrations fluctuating from 1.2 ± 0.6 items m -3 at Ben Tre to 303.9 ± 259.9 items m -3 at Cao Lanh (Fig. 3a). The average concentration of fibres in the surface water of the whole river system % to 87 %) followed by red fibres (10 % to 23 %), with the total percentage of other colours was lower, between 3 % to 18 % (Fig. 7b).

Chemical composition of microplastics

In surface water, FTIR-ATR results showed that 88 % of the tested particles were microplastics, including 67 % polyethylene (PE) and polypropylene (PP), 19 % polyester, 14 % other polymers (Table 3). In sediment, 64 % of the tested particles were microplastics, including 33.3 % polyester, 33.3 % PE, PP, and PE-PP, 16.7 % rayon, 16.8 % other polymers.

Discussions

Comparison to worldwide and local contamination level

The observation of microplastics in all replicates of both surface water and sediment across sampling sites confirmed the contamination of microplastics in the northern branches of the MRD. The average was 49.2 ± 130.9 items m -3 , with concentrations varying from 1.1 ± 0.5 fibres m -3 at Ben Tre to 279.6 ± 247.0 fibres m -3 at Cao Lanh (Table 2a; Fig. 3b). The average concentration of fragments was 4.6 ± 10.0 fragments m -3 , varying from 0.1 ± 0.03 fragments m -3 at Ben Tre to 24.3 ± 13.0 fragments m -3 Cao Lanh (Fig. 3c).

In the average concentration of microplastics over the whole river system was 6.0 ± 2.0 items g -1 . Microplastics were observed in both replicates at all the sampling sites (Table 2b). Microplastic concentration fluctuated from 3.3 ± 1.1 items g -1 at Tra Vinh to 7.9 items g -1 at My Tho (Fig. 3a). The average concentration of fibres in the sediment of the entire river system was 5.8 ± 1.9 fibres g -1 , varying from 3.3 ± 1.1 fibres g -1 at Tra Vinh to 7.6 ± 1.1 fibres g -1 at Ben Tre (Fig. 3b). The average concentration of the fragments was 0.1 ± 0.2 fragments g -1 . No fragments were observed in Cao Lanh, Cho Lach, and Tra Vinh, and for the other sites, fragment concentrations varied from 0.2 ± 0.0 fragments g -1 at My Tho to 0.4 ± 0.3 fragments g -1 at Vinh Long (Fig. 3c).

2.

Morphology of microplastics 1.

Microplastic shapes

In both surface water and sediment, the observed microplastic shapes included fibres and fragments, with fibre being predominant. Both fibres and fragments were observed in surface water at all sites, with fibres representing 85 % and fragments the remaining 15 %. Fibres varied slightly from 77 % at My Tho to 91 % at Cao Lanh (Fig. 4a). In sediment, fibres represented 98 % of the microplastics over the river system and varied from 95 % at My Tho to 100 % at Cao Lanh, Cho Lach, and Tra Vinh (Fig. 4b), suggesting that only a few fragments were observed in the sediment, with no fragments being found in Cao Lanh, Cho Lach, and Tra Vinh.

2.

Microplastic size In surface water, the median fibre length over the river system was 1235 μm (Fig. 5a) and varied from 1041 μm at My Tho to 1914 μm at Tra Vinh (Fig. 6a). The median fragment area over the river system was 142,174 μm 2 (Fig. 5b) and varied from 108,424 μm 2 at Cao Lanh to 228,042 μm 2 at Tra Vinh (Fig. 6b).

In the sediment, the median fibre length over the river system was 1060 μm (Fig. 5a) and varied between sampling sites from 845 μm at Tra Vinh to 1316 μm at My Tho (Fig. 6c). The median fragment area over the river system was 179,672 μm 2 (Fig. 5b).

Microplastic colour partition

In surface water, microplastics of siX colours were observed over the river system (blue, red, white, green, yellow, and grey). Colour partition of microplastics showed a dominance of blue fibres (50 % to 69 %), followed by red fibres (24 % to 29 %) and white fibres (4 % to 29 %). Other colours included green, yellow, and grey with a total percentage of 3 % to 15 % (Fig. 7a). Over the whole river system, seven colours were observed in sediment (blue, red, white, green, yellow, grey, and black). Colour partition of microplastics showed a dominance of blue fibres (67 microplastic concentration over the entire area was 53.8 ± 140.7 items m -3 in surface water and 6.0 ± 2.0 items g -1 d.w. in sediment. Compared to other river systems in Vietnam (Table 4), microplastic concentrations in surface water of the Tien River was higher than that of the Red River, Dong Nai River, and Han River in Da Nang, which had concentrations of 2.3 items m -3 , 3.9 items m -3 , and 2.7 items m -3 , respectively [START_REF] Strady | Baseline assessment of m icroplastic concentrations in m arin e and freshwater environm ents of a d evelo p in g Southeast Asian country, Viet Nam[END_REF]. Microplastic abundance in the sediment of the Tien River was higher than that of the sandy sediment in Dau and Sau Beaches in Vung Tau City, Vietnam (1.5-2.0 items g -1 ; [START_REF] Strady | Baseline assessment of m icroplastic concentrations in m arin e and freshwater environm ents of a d evelo p in g Southeast Asian country, Viet Nam[END_REF], and approXimately equal to that of shoreline sediment in Da Nang Beach (9.2 ± 2.1 items g -1 d.w.; Tran [START_REF] Nguyen | Characteristics of microplastics in shoreline sedim ents from a tropical and urbanized beach (Da Nang, Vietnam )[END_REF]. This study was based on the same protocols and observation range size (300-5000 μm) as the aforementioned studies carried out by [START_REF] Strady | Baseline assessment of m icroplastic concentrations in m arin e and freshwater environm ents of a d evelo p in g Southeast Asian country, Viet Nam[END_REF] and Tran [START_REF] Nguyen | Characteristics of microplastics in shoreline sedim ents from a tropical and urbanized beach (Da Nang, Vietnam )[END_REF] and therefore the comparison is more reliable when the protocols are identical. In comparison to the Saigon River, highly impacted by the anthropogenic activities in this water basin, the Tien River, located in the neighboring basin, had approXimately three orders of magnitude lower [START_REF] Lahens | Macroplastic and m icroplastic contam ination assessm ent of a tro p ical river (Saigon River, Vietnam ) transversed by a developing m egacity[END_REF][START_REF] Strady | Tem poral dynam ic of anthropogenic fibers in a tropical river-estuarine system[END_REF].

When compared with worldwide river systems (Table 4), microplastic levels in the surface water of the Tien River was approXimately that same as that of the Qing River, China (170-260 items m -3 ; [START_REF] Wang | Microplastics profile in a typical urban river in Beijing[END_REF], and the Seine River, France (3-106 items m -3 ; [START_REF] Dris | Microplastic co n tam in atio n in an u rb an area: a case study in greater Paris[END_REF]. Further, it was higher than that of the Chao Phraya River Estuary, Thailand (48 ± 8 items m -3 ; Ta and Babel, 2020), 29 assorted rivers in Japan (1.6 ± 2.3 items m -3 , [START_REF] Kataoka | Assessment of the sources and inflow processes of microplastics in the river environm ents of Japan[END_REF], and Northern Dvina River in Russia (0.004-0.01 items m -3 , [START_REF] Zhdanov | Assessment of seasonal variability of input of microplastics from the northern Dvina River to the Arctic Ocean[END_REF], and lower than that of the Orange-Vaal River system in South Africa (0.23 ± 0.27 items L -1 , Weideman et al., 2019), and the Thames river in the United Kingdom (87,750 items m -3 , DevereuX et al., 2022). Sediment in the Tien River also presented higher microplastic levels than that in the Ciwalengke River, Indonesia (1.4-3.5 × 10 -3 items g -1 d.w.; [START_REF] Alam | Microplastic distribution in surface water and sedim ent river around slum and industrial area (case study: Ciwalengke River, m ajalaya district, Indonesia)[END_REF], the Chao Praya River, Thailand (0.04 items g -1 d.w.; [START_REF] Ta | Microplastics pollution with heavy m etals in the aquaculture zone of the Chao Phraya River Estuary, Thailand[END_REF], the Barrow River in Iceland (172.5 ± 116 items kg -1 w.w., [START_REF] Murphy | Heliyon assessment of microplastics in irish river sedim ent[END_REF], and the Qin River in Beibu Gulf, China (0-0.1 items g -1 d.w.; [START_REF] Zhang | Distribution of microplastics in surface water and sedim ents of Qin river in Beibu Gulf, China[END_REF]. It was approXimately the same with that of the St. Lawrence River in Canada (65-7562 items kg -1 d.w., [START_REF] Crew | Distribution , abundance, and diversity of microplastics in the upper St. Lawrence River[END_REF].

Spatial variation of microplastic abundance in the surface water of the Tien River

Among the sampling sites, Cao Lanh was the only site in a secondary tributary of the Tien River, situated in a small secondary tributary flowing through the urban area of Cao Lanh City, the Cai Sao Thuong River. Thus far, only the main distributaries of the Tien River have been used to account for the spatial variation of microplastic contamination management, and wastewater treatment plant effluent on the abundance of microplastics in surface water (Amrutha and Warrier, 2020; [START_REF] Kataoka | Assessment of the sources and inflow processes of microplastics in the river environm ents of Japan[END_REF][START_REF] Strady | Baseline assessment of m icroplastic concentrations in m arin e and freshwater environm ents of a d evelo p in g Southeast Asian country, Viet Nam[END_REF][START_REF] Talbot | Microplastics in freshwater: a global review of factors affecting spatial and tem poral variations[END_REF]. Urban areas are evenly scattered on both banks of the Tien River and its distributaries and fall within our study area. These urban areas have a population of approXimately 100,000 inhabitants in Tra Vinh City to over 220,000 inhabitants in My Tho City (Table 1). These urban areas may be main sources of microplastics that are released into the environment through wastewater discharge. In 2020, after a sampling survey, a centralised wastewater treatment plant was put in place to treat domestic wastewater, which was before directly flowing into the urban canals and rivers without treatment. The remarkable concentration of microplastics at the Cao Lanh site can be taken as an example of direct microplastic release from an urban area. In the MRD, aquaculture and agriculture are the main livelihoods of local residents. In the Tien River, there were many fish raft villages that use fishing nets and floats.

Outside of the urban areas along the river are large areas of agricultural activities, such as rice paddy fields and other agricultural products.

Accordingly, along its flow to the estuary, the Tien River and its distributaries may continuously receive microplastics released from wastewater effluents, aquaculture, and agriculture. Concerning river water discharge, several publications presented it as one of the hydrodynamic factors dominating the presence of microplastics in water such as in nival tributaries of the Rhine River in Switzerland and the pluvial Lower Rhine River in Germany [START_REF] Mani | Seasonal m icrop lastics var iation in nival and pluvial stretches of the Rhine Riverfrom the swiss catchm ent towards the North Sea[END_REF] and in the torrential Ofanto River of Italy (Campanale et al., 2020a(Campanale et al., , 2020b)).

As reported by the MRC-KOICA ( 2000), the Tien River had high water discharge of 3720 m 3 s -1 in February 2000, which may have diluted the concentration of microplastics. The dilution effect can be evidenced by comparing the concentration of microplastics at the Cao Lanh site with other sites. Cao Lanh City has a population of 163,892 inhabitants, and the Cai Sao Thuong River's surface water had a conthe entire area, varying from 1.2 ± 0.6 items m -3 at Ben Tre to 7.4 ± 6.4 items m -3 at My Tho for surface water and from 3.3 ± 1.1 items m -3 at Tra Vinh to 7.9 items m -3 My Tho for sediment. We hypothesise that the concentrations of microplastics in this area originate from two factors: (i) the release of microplastics from anthropogenic activities, and (ii) water discharge. Previous studies have demonstrated the influence of anthropogenic factors such as population distribution, land use, waste in this area. These are, the Tien River (My Tho), the Ham Luong River (Cho Lach a nd Ben Tre), and the Co Chien River (Vinh Long and Tra Vinh). The concentration of microplastics maintained a stable level over centration of 303.9 ± 259.9 items m -3 , (no water discharge data available). Although the Tien River received microplastics from not only the Cai Sao Thuong River but also from other urban cities which are similar in size to Cao Lanh City (Table 1) and from agriculture a nd aquaculture areas along its flow, the concentration of microplastics was substantially smaller than that of the Cao Lanh site. Accordingly, it can be assumed that the high water discharge in the river serves to dilute the effect of the continuous release of microplastics as it flows into the estuary.

Factors affecting the abundance of microplastics in sediment

The accumulation of microplastics in sediments is primarily affected by (i) anthropogenic activities, (ii) hydrodynamic conditions of the environments (water dynamics, water depth, flow velocity), (iii) physical Fragm ent concentration (fragm ents g -1 )

Fibre concentration (fibres g -1 )

Fig. 5. BoXplots of a) microplastic fibre length (μm) and b) microplastic fragment area (μm 2 ) observed in all samples of surface water and sediment in the Tien River. d.w.), as shown in Fig. 3a. [START_REF] Zhang | Microplastic pollution in th e Yangtze River basin: heterogeneity of ab u n d an ces and characteristics in different en viro n m en ts[END_REF] compiled the published results of 624 sampling sites in different environments of the Yangtze River Basin and observed a correlation between the socioeconomic factors (e.g. population density and urbanisation rate) and microplastic abundance in surface waters. However, this was not mirrored in sediments, perhaps due to the complex mechanisms and dynamics of microplastic transport and deposition. Along the Brisbane River, Australia, [START_REF] He | Influential factors on microplastics occurrence in river sedim ents[END_REF] reported the influence of different land use types and population density on the microplastic types rather tha n their concentrations in sediment collected at 22 sites. In the Tien River, the impact of anthropogenic activities indicating by high microplastic concentration in surface water at Cao Lanh were not observed via the concentrations measured in sediment, i.e. microplastic concentration in sediment at Cao Lanh was almost same as that of other sites. Accordingly, the anthropogenic activities were less important in sediment of the Tien River.

Concerning the hydrodynamic conditions, one important factor that increases the deposition of microplastics is the slowdown of the flow velocity [START_REF] Ding | Microplastics in surface waters and sedim ents of the Wei River, in the northwest of China[END_REF]Gerolin et al., 2020); microplastics start to sink in calm environments, especially in areas with long water residence times such as dams or bays. The Tien River flow dynamics are strongly affected by the tidal regime of Vietnam's East Sea up to Cambodia during the dry season. EXcept Cao Lanh, the other five sites were located in the main stream and main distributaries of the Tien River and therefore the flow condition at these sites were affected by a dynamic hydrological condition. Cao Lanh, however, was located in the Cai Sao Thuong River, a small secondary tributary of the Tien River. This small river was facing the issue of water pollution due to sediment deposition inducing slow flow and obstruction and in 2020 the local government approved a plan of sediment dredging to increase the flow efficiency (VNPCCL, 2020). Thus, it can be supposed that the flow velocity at this site was much lower than that at the other sites on the main distributaries. Concerning microplastic concentration, at Cao Lanh, high concentration of microplastics in surface water, however, was not reflected in sediment which presented a similar low microplastic concentration with the other sites. Accordingly, hydrodynamics conditions may not be an important factor controlling the deposition of microplastics in sediment in this area. Kumar et al. (2021b) reviewed recent studies on the transport and deposition of microplastics in the riverine system and discussed the physical properties of microplastics including plastic particle density, shape, and size are important factors controlling the deposition of microplastics. In addition, the aggregation process due to microbial colonization and biofilm development depending upon the microplastics properties, microorganisms species, and water environmental conditions. In the Tien River system, in comparison with microplastic fragments, fibres was found more predominant (Fig. 4). Moreover, fibres shared higher proportion in sediment (95 % to 100 %) than in surface water (77 % to 91 %). As in Fig. 5a, the median length of fibres was smaller in sediment (1060 μm) than in surface water (1235 μm), a nd the fibres in sediment was significantly shorter than in water (Mann-Whitney test, p-value < 0.0001). Accordingly, in the Tien River, the deposition of microplastics from the surface water to the sediments was prior to fibres, and shorter fibre length.

Future trends of microplastic abundance in the Mekong River delta: the need of a global plastic assessment

The MRD is facing various challenges which impact its sustainability: increasing sea level rise and salinity intrusion [START_REF] Eslami | Tidal am plification and salt in tru sio n in the Mekong Delta driven by an th ro p o gen ic sedim ent starvation[END_REF], changes in flood regime dynamic [START_REF] Park | Dram atic decrease of flood frequency in the Mekong Delta due to river-bed m ining and dyke construction[END_REF], change of land use [START_REF] Vu | Datasets of lan d use change and flood dynam ics in the vietnamese m ekong delta[END_REF], increasing urbanisation [START_REF] Nguyen | Assessment on controlling factors of urbanization possibility in a newly developing city of the vietnam ese Mekong delta using logistic regression analysis[END_REF], increasing subsidence [START_REF] Erban | Groundwater extraction, land su b sid ence, and sea-level rise in the Mekong Delta, Vietnam[END_REF] agricultural transformation [START_REF] Nguyen | Drivers of agricultural transform ation in the coastal areas of the vietnam ese Mekong delta[END_REF] and increasing tourism [START_REF] Vu | Datasets of lan d use change and flood dynam ics in the vietnamese m ekong delta[END_REF]. All those challenges can be interconnected, with for example, increasing sea level rise causing land use shift, with more intensive rice cropping (increasing double rice and triple rice cropping) and the development of inland characteristics of microplastics (such as density, shapes, and size), and the aggregation process due to microbial colonization and biofilm development [START_REF] Crew | Distribution , abundance, and diversity of microplastics in the upper St. Lawrence River[END_REF]Gerolin et al., 2020;[START_REF] Huang | Th e occurrence and abundance of microplastics in surface water and sedim ent of the West River downstream , in the south of China[END_REF]Kumar et al., 2021b;[START_REF] Tien | Microplastics in water, sedim ent and fish from the Fengshan River system: relationship to aquatic factors and accum ulation of polycyclic arom atic hydrocarbons by fish[END_REF]Wu et al., 2020;[START_REF] Xu | Microplastics in sedim ents from an in terco n n ected river-estu ary region[END_REF].

The impact of anthropogenic activities on microplastic contamination in sediment was observed at higher concentrations due to the industrial wastewater discharge, sewage release, and high population density and urbanisation [START_REF] Alam | Microplastic distribution in surface water and sedim ent river around slum and industrial area (case study: Ciwalengke River, m ajalaya district, Indonesia)[END_REF][START_REF] Horton | Microplastics in fresh water and terrestrial environm ents: evalu atin g the current understanding to identify the knowledge gaps and future research priorities[END_REF][START_REF] Huang | Th e occurrence and abundance of microplastics in surface water and sedim ent of the West River downstream , in the south of China[END_REF]. In the MRD sediment, the concentrations of microplastics were stable across different areas, varying from 3.3 ± 1.1 items g -1 d.w. at Tra Vinh to 7.9 items g -1 d.w. at Ben Tre (Fig. 3a and Table 2b). Although the concentration of microplastics in surface water at Cao Lanh was hundreds of times higher tha n that at the other sites, the microplastic concentration in sediment at Cao Lanh (5.5-7.9 items g -1 d.w.) was in the same range as that at the other sites (2.5-8.7 items g -1 aquaculture, which along with aggravating subsidence, is increasing floodings, especially urban flooding during equinoX high tides events. Unfortunately, all those changes may also impact directly or indirectly the abundance of microplastics in the MRD receiving water systems at present and in the near future. Intensification of double and triple rice cropping can lead to a large amount of plastic and microplastic release in soils and irrigation waters, as observed in China [START_REF] Zhou | Microplastics in agricultural soils on the coastal plain of Hangzhou Bay, East China: m ultiple sources other than plastic m ulching film[END_REF]. Rice farming involves plastic from seed packaging, fertilizer and pesticide packaging, mulch, seedling trays, pesticide sprayers and storage bags. In agriculture soils from China, macroplastics ranged from 0.1 to 324.5 kg ha -1 and were positively correlated to the mass of plastic mulch used per hectare while microplastics, dominated by fragments a nd fibres, were observed on all soils subjected to plastic mulching with microplastic abundance increasing with the plastic mulching use duration in the soils, being up to 1075.6 ± 346.8 pieces kg -1 in a soil of 24 years of continuous mulching [START_REF] Huang | Agricultural plastic m ulching as a so u rce of microplastics in the terrestrial environm ent[END_REF][START_REF] Zhou | Microplastics in agricultural soils on the coastal plain of Hangzhou Bay, East China: m ultiple sources other than plastic m ulching film[END_REF]. The development of inland aquaculture due to salinity intrusion is also a point source of microplastic to the environment, as observed in surface sediments from aquaculture ponds in Northern Vietnam [START_REF] Le | First observation of microplastics in surface sedim ent of so m e aquaculture ponds in Hanoi city, Vietnam[END_REF] where high microplastic concentrations (e.g. 2767 ± 240 items kg -1 d.w.) were measured and might derived from plastic equipment (buoys, barrel, lines, hanging line, food bags) commonly used in aquaculture farming activity. Anthropogenic activities taking place in urban or suburban areas are also an important source of microplastic deposition in atmospheric fallouts (71-917 items m -2 d -1 in Ho Chi Minh City, Truong et al., 2021) and in surface road dust (19.7 ± 13.7 items m -2 in Da Nang, Yukioka et al., 2020). The part of microplastics reaching the aquatic environment from those sources few, as they mainly deposit on terrestrial environment but with increasing urban flooding events during rainy season, coupled to increasing subsidence, equinoX high tides are getting more and more frequent and can remobilized deposited microplastics into the aquatic environment. In 2019, tourism activity welcomed 47 million domestic and foreign visitors in the MRD [START_REF] Vu | Percep tio ns of key stakeholders towards su stain able tourism d evelo p m en t: a case stu d y in Mekong Delta, Vietnam[END_REF], leading to an important use of plastics, specifically single use ones. In Vietnam, the EXtended Producer Responsibility decree (Decree 08/2022/ND-CP, 2022) is reinforcing circular economy and plastic recycling, mainly via mechanical recycling. This process, common in Vietnam, was demonstrated as a point source of microplastic pollution in the receiving environments, especially when wastewaters were not treated specifically [START_REF] Suzuki | Mechanical recycling of plastic waste as a point source of m icroplastic pollution[END_REF], which is often the case at the moment.

In this complex environmental, economic and societal context, there is a need to assess microplastic concentrations key aquatic and agricultural soil environments of the MRD in order to set up a baseline and evaluate its pollution level. Then, from this baseline, decision makers along with scientists will be able to discuss and decide adapted remediation or ban to prevent the increasing microplastic pollution of the MRD. The assessment phase through a holistic and concerted approach is a key step to prevent its pollution.

Conclusions

The microplastic contamination in the Tien River system predominantly comprised fibres, and was found at concentrations of 53.8 ± 140.7 items m -3 in surface water and 6.0 ± 2.0 items g -1 d.w. in sediment. The presence of stable microplastic concentration in the main streams of the Tien River indicates the role of the hydrodynamics of the river in diluting microplastics released from continuous sources along the river whereas higher concentrations in smaller streams, less affected by large hydrodynamic processes, pointed out local pollution which may affect the ecosystem. In the near future, the MRD will face important environmental and societal challenges which may reinforce its This study [START_REF] Strady | Baseline assessment of m icroplastic concentrations in m arin e and freshwater environm ents of a d evelo p in g Southeast Asian country, Viet Nam[END_REF] 6.0 ± 2.0 item s g -1 d.w.

3.9 item s m -3 2.7 item s m -3 1.5-2.0 item s g -1 d.w. 9.2 ± 2.1 item s g [START_REF] Scherer | Com parative assessment of microplastics in water and sedim ent of a large European river[END_REF]

Fig. 1 .

 1 Fig. 1. Study area map showing the surface water and sediment sampling sites along the Tien River.

Fig. 2 .

 2 Fig. 2. Stereomicroscopic images of microplastics collected in the Tien River.

Fig. 3 .

 3 Fig. 3. Average concentrations of a) microplastics, b) fibres, and c) fragments in surface waters (blue) and sediments (orange) at each sampling site along the Tien River. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 4 .

 4 Fig. 4. Microplastic shape partition, i.e. fibres and fragments, in a) surface water and b) sediment at each sampling site in the Tien River.

Fig. 6 .

 6 Fig. 6. BoXplots of a) microplastic fibre length (μm) and b) microplastic fragment area (μm 2 ) in surface water and c) microplastic fibre length (μm) in sediment observed at each sampling site in the Tien River.

Fig. 7 .

 7 Fig. 7. Microplastic colour partition, i.e. red, blue, grey, white, black, yellow, and green, in a) surface wate r and b) sediment in the Tien River. (For interpretation of the references to colour in this figure legend, the re ade r is referred to the web version of this article.)

Table 1

 1 Description of sampling sites with the population of nearby urban in 2016 and the description of each site.

	Sam pling	Coordinate	River	Site description
	site

• 27 ′ 05 ′′ N, 106 • 27 ′ 05 ′′ E Cai Sao Thuong River (small secondary tributary, low water discharge) Closed to a residential area (My Tra residential area, 500 households). This urban river flow through the center of Cao Lanh City (population 163,892 inhabitants) Near the fishing raft area My Tho City (population 228,385 inhabitants) is on the left bank • 01 ′ 47 ′′ N, 106 • 18 ′ 19 ′′ E Co Chien River (m ain distributaries)

Table 2a

 2a Concentrations of microplastics, fibres, and fragments in surface waters of each replicate at each sampling site.

	Site	Microplastic	Fragm ent		Fibre concentration
		concentration (item s	concentration	(fibres m -3 )
		m -3 )		(fragm ents m -3 )
		Rep. 1	Rep. 2	Rep. 1	Rep. 2	Rep. 1	Rep. 2
	Cao Lanh	120.1	487.7	15.1	33.4	105.0	454.3
	My Tho	2.9	11.9	0.9	2.3	1.9	9.6
	Cho Lach	2.1	3.7	0.3	0.9	1.8	2.9
	Ben Tre	0.8	1.6	0.1	0.1	0.7	1.4
	Vinh Long	5.4	4.2	0.6	0.6	4.8	3.6
	Tra Vinh	1.9	2.8	0.2	0.4	1.7	2.4

Table 2b

 2b Concentrations of microplastics, fibres, and fragments in sediments of each replicate at each sampling site.

	Site	Microplastic
		concentration (item s
		g -1 )
		Rep. 1	Rep. 2	Rep. 1	Rep. 2	Rep. 1	Rep. 2
	Cao Lanh	5.5	7.9	0	0	5.5	7.9
	My Tho	7.9	7.9	0.2	0.6	7.7	7.3
	Cho Lach	3.2	6	0	0	3.2	6
	Ben Tre	7	8.7	0.2	0.3	6.8	8.4
	Vinh Long	5.7	5.5	0.2	0.2	5.5	5.3
	Tra Vinh	2.5	4	0	0	2.5	4

Table 3 Chemical

 3

	Polym er type		Quantity	Percentage among
				plastics
	(a) Surface water
	Plastic (88 %)	PE, PP	35	67 %
		Polyester	10	19 %
		Acrylic	3	6 %
		Alkyd	1	2 %
		Polysterene	2	4 %
		Pheno Xy resin	1	2 %
	Non-plastic	Mineral, calcium carbonate,	7
	(12 %)	unidentified
	(b) Sedim ent
	Plastic (64.3	Polyester	6	33.3 %
	%)	PE, PP, PE-PP	6	33.3 %
		Rayon	3	16.7 %
		Acrylic	1	5.6 %
		Polysterene	1	5.6 %
		Pheno Xy resin	1	5.6 %
	Non-plastic	Cellulose, cotton, m ineral	10
	(35.7 %)

compositions of microplastics in surface water (a) and sediment (b) of the Tien River from FTIR-ATR analysis.

Table 4

 4 Synthesis of microplastic abundance in water and sediment of worldwide aquatic environments.

	range

  -1 d.w.

	300-5000 μm	(Tran Nguyen et al., 2020)
	50-5000 μm	(Lahens et al., 2018)
	50-5000 μm	(Wang et al., 2020)
	1-5000 μm	(Liu et al., 2020)
	50-5000 μm	(Yin et al., 2022)
	0-5000 μm	(Wu et al., 2022)
	20-5000 μm	(Ji et al., 2021)
	300-5000 μm	(Zhang et al., 2020)
	50-5000 μm	(Ta and Babel, 2020)
	1-5000 μm	(Sulistyowati et al., 2022)
	<100 μm-5000 μm	(Alam et al., 2019)
		(Kataoka et al., 2019)
	1-5000 μm	(Zhdanov et al., 2022)
	50-5000 μm	(Correa-araneda et al.,
		2022)
	125-5000 μm
	150-5000 μm
	100-5000 μm
	200-5000 μm
	100-5000 μm
	100-5000 μm
	10-5000 μm
	25-5000 μm
	300-5000 μm

Acknowledgement

This study was undertaken under the framework of the JEAI PLASTIC research team supported by the French National Research Institute for Development (IRD) and under the framework of CARE-RESCIF initiative and financially supported by the Ho Chi Minh City University of Technology (HCMUT), VNU-HCM under grant number Tc-ĐCDK-2019-01.

Data availability

dataverse DataSudshttps://doi.org/10.23708/P9HYLM

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.


Ingrid Fasshauer

OPEN INNOVATION BUSINESS MODELS-THE CASE OF LIVING LABS IN FRANCE

Keywords: open innovation, business models, living labs

. In addition they have to take into account the interests of different stakeholders. We investigate open innovation business models through the example of living labs.

. The question of the business model is crucial. Based on a survey answered by nine living labs in France, the main objective of this research is to find out the main dimensions of the business models of living labs and by extension the dimensions of the business models of open innovation intermediaries. It highlights three forms of value generation: knowledge creation, social impact and economic value. Revenues can be exclusively public, exclusively private or mixed. As regards the sharing of value, it is a concern for several living labs which respond by ensuring the dissemination of their innovations within their network or to a wide audience. Only research-oriented laboratories have intellectual property protection practices. We finally propose a typology of three living labs business models archetypes. This exploratory research contributes both to living labs and to open innovation literature by analyzing examples of business models for open innovation intermediaries.

INTRODUCTION

Living labs are ecosystems in which end users (customers, users, patients, etc.) and other stakeholders are involved over a long period in the development of an innovation, in a real environment, using an approach of iterative research combining different methods [START_REF] Schuurman | Smart ideas for smart cities: investigating crowdsourcing for generating and selecting ideas for ICT innovation in a city context[END_REF]. The creation of a living lab is the result of various initiatives. While some are supported by laboratories or research organizations, others are carried out by companies, public organizations, even not for profit organizations or individuals. Although their structures are different, they are characterized by five common dimensions [START_REF] Ballon | Living labs: concepts, tools and cases[END_REF]: (1) active user involvement, (2) real life environment, (3) participation of multiple stakeholders, (4) multimethod approach and (5) co-creation. Very focused initially on technological innovation, then on subjects such as health and smart cities, living labs are increasingly identified in relation to social innovation [START_REF] Edwards-Schachter | Fostering quality of life through social innovation: A living lab methodology study case[END_REF][START_REF] Hillgren | Prototyping and infrastructuring in design for social innovation[END_REF]. Indeed, they encompass societal and technological dimensions simultaneously in a businesscitizen-government-university partnership. These structures are developing in France and around the world. The European Network of Living Labs (ENoLL) thus claims 150 active members in 2018. Knowing that more than 400 different structures have received the label since 2006, this gives an indication of the fragility of the economic model of such structures. They often find it difficult to translate the value created into a sustainable revenue model. Consequently, a large number of living labs are of an unwanted temporary nature [START_REF] Leminen | Living Labs as open-innovation networks[END_REF].

We define business models as the content, structure and governance of transactions inside an organization and between the organization and its external partners in support of the organization's creation, delivery and capture of value [START_REF] Santos | Toward a theory of business model innovation within incumbent firms[END_REF][START_REF] Zott | The business model: recent developments and future research[END_REF]. They can be considered as conventions that relate to the generation of value, its remuneration and its sharing [START_REF] Verstraete | A conventionalist theory of the business model in the context of business creation for understanding organizational impetus[END_REF] and they represent a broader conceptualization of value co-creation [START_REF] Zott | The fit between product market strategy and business model: Implications for firm performance[END_REF]. As far as value generation is concerned, living labs do not directly develop products or services. They serve as a link between research and citizens in a real life environment [START_REF] Franz | Chances and Challenges for Social Urban Living Labs in Urban Research[END_REF] and function as intermediaries for open innovation [START_REF] Katzy | Designing viable business models for living labs[END_REF]. They thus can be considered as open innovation intermediaries [START_REF] Howells | Intermediation and the role of intermediaries in innovation[END_REF][START_REF] Ollila | Managing open innovation: Exploring challenges at the interfaces of an open innovation arena[END_REF]. Under these conditions, the identification of the generated value is not obvious. The main problem with the sharing of the value is related to the collective nature of the innovation process, which is the product of multiple stakeholders, the main role being played by users who are often volunteers and unpaid. The fact that certain actors seek to appropriate or obtain a financial gain from part of the co-created value can potentially create tensions [START_REF] Bonaccorsi | Entry strategies under competing standards: Hybrid business models in the open source software industry[END_REF][START_REF] Chesbrough | Open innovation and strategy[END_REF]. This research is based on the results of a questionnaire answered nine living labs in France. It aims to identify the value generated by living labs, the way in which it is remunerated and shared between the different stakeholders. A literature review (part 1) will highlight the great fragility of the economic models of living labs The methodology that led to the development and then the analysis of the survey will be explained in part 2 then the results leading to a mapping proposal will be presented in part 3. Finally, we will discuss these results and outline the followup that could be given to this research.

Weak business models for living labs

Financial sustainability seems to be the essential condition for living labs to become sustainable [START_REF] Veeckman | Linking living lab characteristics and their outcomes: Towards a conceptual framework[END_REF]. However Schuurman in 2015 noted a mortality rate of more than 40% in the living labs labelled by the European Network of Living Labs, ENoLL. Through a literature review, we highlight the nature of the value generated by living labs, their sources of income and the problems that arise in terms of sharing value, including its governance.

Open business models in tension between value proposition and value capture

Research on the business models of living labs is spread over two levels of study: the business models of the living lab structure and the business models of the projects led by the living labs [START_REF] Rits | Exploring the benefits of integrating business model research within living lab projects[END_REF]. This research is concerned with the first level.

Business model has been a concept that has attracted the attention of researchers since the 1990s [START_REF] Zott | The business model: recent developments and future research[END_REF]. The majority of studies converge to assess that business models denote the company's core logic for creating and capturing value [START_REF] Saebi | Business models for open innovation: Matching heterogeneous open innovation strategies with business model dimensions[END_REF], the understanding of these two logics being crucial for the sustainability of the structure.

For the rest of the research we rely on [START_REF] Verstraete | A conventionalist theory of the business model in the context of business creation for understanding organizational impetus[END_REF] model which proposes an analysis on three dimensions: value generation, sources of revenues and value sharing. Although this model is not well-known outside French-speaking countries, it has proved to be particularly well suited for business with a social dimension, which is the case for living labs. More especially it points out the interest of value sharing rather than value capture like this is the case in most of the business models framework [START_REF] Teece | Business models, business strategy and innovation[END_REF].

The business model is not a simple representation of how an organization creates value but it is also a cognitive device [START_REF] Chesbrough | Open innovation: a new paradigm for understanding industrial innovation[END_REF] through which decisions are evaluated, adopted and find economic materialization [START_REF] Leroux | Innovation ouverte et évolution des business models dans les pôles de compétitivité: le rôle des intermédiaires dans la création variétale végétale[END_REF]. This characteristic is particularly important for open innovation where the innovation process relies on purposively managed knowledge flows across boundaries [START_REF] Chesbrough | Explicating open innovation: Clarifying an emerging paradigm for understanding innovation[END_REF] with multiple and heterogeneous stakeholders who must succeed in producing compromises beyond their divergent interests [START_REF] Leroux | Négociation public/privé et coévolution stratégique dans un biocluster[END_REF]. The governance proves then to be a key dimension, which need to be taken into account by studying business models. We then propose four dimensions for studying living labs business models (see figure 1).

The open innovation model relies on pecuniary and non pecuniary mechanisms [START_REF] Chesbrough | Explicating open innovation: Clarifying an emerging paradigm for understanding innovation[END_REF] which have to be taken into account in business models.

Open innovation induces tensions between value generation which requires openness and value capture which requires more protective processes [START_REF] Chesbrough | Value creation and value capture in open innovation[END_REF]. The living lab, as open innovation intermediary [START_REF] Almirall | Living Labs: arbiters of mid-and ground-level innovation[END_REF], is at the center of this tension.

Different natures of value generation for living labs

A living lab has multiple resources linked to its different stakeholders who all participate in the co-production of innovation, its multiple research methods and its ability to carry out tests in a real environment. They are able to facilitate access to external ideas, whether commercial or scientific. Through their original and often unprecedented associations of heterogeneous stakeholders, they can be qualified as "architects of the unknown" [START_REF] Agogué | Managing innovative design within the health ecosystem: the living lab as an architect of the unknown[END_REF] and thus clear new ground to act in situations where technologies, markets and the involved actors are partially unknown.

But the main difference to other open innovation methodologies is the particular interest to users [START_REF] Baccarne | Why collaborate in longterm innovation research? An exploration of user motivations in Living Labs[END_REF]. All these resources allow it to create economic value by co-producing a response as close as possible to the needs of customers and users. From a market point of view, they make it possible to improve new offers and to test the market-product adequacy [START_REF] Ballon | The effectiveness of involving users in digital innovation: Measuring the impact of living labs[END_REF]. They thus increase the chances of success of an innovation and reduce time to market and they have the potential to improve user value [START_REF] Almirall | Open versus closed innovation: A model of discovery and divergence[END_REF].

If living labs take part in creating economic value, it does not mean that they realize this economic value by themselves. According to [START_REF] Leminen | Living Labs as open-innovation networks[END_REF], living labs create either knowledge (utilizer-driven and provider-driven living labs), new strategies of development (enabler-driven living labs) or solutions to users specific needs (user-driven living labs). As open innovation intermediary, they produce knowledge which can then be integrated into innovative products and services marketed by one or other of the stakeholders. However, traditionally knowledge is not valued as such, but its valuation is integrated into the innovative product or service. The economic value is then made visible only by the stakeholders.

In addition to economic value, through the attention given to users specific needs, living labs produce environmental and social effects [START_REF] Bergvall-Kåreborn | Living Lab: an open and citizen-centric approach for innovation[END_REF][START_REF] Ståhlbröst | A set of key-principles to assess the impact of living labs[END_REF] and strengthen social cohesion [START_REF] Leminen | Living Labs as open-innovation networks[END_REF][START_REF] Schuurman | The impact of living lab methodology on open innovation contributions and outcomes[END_REF].

Even all living labs have common characteristics (Ballon and Shuurmann, 2015), they demonstrate a variety of different activities. They thus can be classified by their activity sector (healthcare, urbanism, education, etc.), by their form of user participation (Dell'Erra and Landoni, 2014), by their innovation tool [START_REF] Leminen | Categorization of innovation tools in living labs[END_REF]. [START_REF] Leminen | Living Labs as open-innovation networks[END_REF] proposed a typology taken into account the dominant actor of the living lab and its purpose. It highlights four types of living labs which main properties are summarized in table 1.

Innovation approach 1

Inhalation-dominated

Exhalationdominated

Exhalationdominated

Inhalation-dominated

They point out that a specific stakeholder plays a dominant role according to its own purposes.

This infuences different dimensions like the purpose of the living lab, the outcomes, the coordination and the innovation approach. The expected outcome nevertheless should also cover the interests of the other stakeholders for them to accept to take part in the innovation process [START_REF] Leminen | A typology of creative consumers in living labs[END_REF].

Living labs revenues: a mixture of public and private funding

Funding plays a major role in the development of collaborative innovation.

Most living labs depend mainly on subsidies and public aid [START_REF] Brankaert | Innovate dementia: the development of a living lab protocol to evaluate interventions in context[END_REF] while others operate through project based funding [START_REF] Hossain | A systematic review of living lab literature[END_REF].

Indeed, from 2006, the European Union identified living labs as devices allowing to increase the European innovation potential, stimulating job creation and wealth generation [START_REF] Nesti | Co-production for innovation: the urban living lab experience[END_REF].

European funds were then dedicated to the priming of these structures. In general, living labs are likely to receive public subsidies for territorial economic development, research, innovation or social impact. These grants may, depending on the case, concern the structure or one or other of the projects developed by the living lab.

However, public funding has evolved in recent years. [START_REF] Prouteau | Evolutions et transformations des financements publics des associations[END_REF] thus distinguish three trends in France:

-Growing privatization of funding, in particular by involving users in the funding of the service provided,

-Rise of local authorities in public funding in the face of State disengagement -Decrease in subsidies in favor of the rise in power of public procurement through calls for projects or calls for expressions of interest. This trend can be compared to an instrumentalization of not for profit organizations according to the priorities defined by the public authorities (Leroy 2019, p 96). But the main risk of this funding is its temporary nature which can have the effect of launching the living labs into a headlong rush to capture funding even if it means deviating from their initial project [START_REF] Fasshauer | Crowdsourcing public et innovation territoriale: le cas d'un living lab rural[END_REF], all the more that it induces a strong competition among commercial, not for profit and hybrid organizations [START_REF] Bennett | Changing citizenship in the digital age[END_REF] While these kinds of funding are acceptable short-term option, it does not guarantee long-term sustainability and growth (Guzman et al., 2013). Problems often arise after initial public funding has ended [START_REF] Katzy | Designing viable business models for living labs[END_REF][START_REF] Grezes | Embedding Business Model for Sustainable Collaborative Innovation in African Living Labs[END_REF][START_REF] Burbridge | Business models for sustainability in living labs[END_REF].

The sustainability of these structures therefore depends on their ability to become autonomous and generate sufficient income for the service provided (Garcia-Guzman et al., 2013;[START_REF] Grezes | Embedding Business Model for Sustainable Collaborative Innovation in African Living Labs[END_REF][START_REF] Katzy | Designing viable business models for living labs[END_REF][START_REF] Leroy | Living labs as engagement models for innovation[END_REF].

Living labs are therefore likely to use different types of income as shown in Table 2. Traditionally, value is captured by intellectual property management. Open innovation gives nevertheless new status to intellectual property rights that are seen as vectors for openness that help the firms identify partners and build secure relationships (Cohendet and Penin, 2011;[START_REF] Ayerbe | Management Innovation and Open Innovation: For and Towards Dialogue[END_REF]. Intellectual property can nevertheless in some cases bring restrictions to the exchange of knowledge [START_REF] Ayerbe | Quel management des DPI dans les business models ouverts?[END_REF]. Some open innovations structures, inspired by the example of free software communities, turn to specific open management methods of intellectual property such as "creative commons". In case of collective creation of value, these devices make it possible to identify the contribution of each partner while framing the rights of use and preserving the generation of value for the stakeholders by allowing wide dissemination. They are therefore part of a concern to contribute to the common good, in line with the desire to create social value. However, to our knowledge, there is no study on the effective use of creative commons in living labs.

Moreover some living labs work on usage innovations based on existing technologies. In this case, patents or other intellectual property protections prove to be unsuitable. Nevertheless open innovation models, beyond the undeniable advantages in terms of acquisition of external knowledge and skills, can generate perverse effects when some stakeholders contribute little but can take ownership of ideas. In addition, living labs are based on the contribution of users, who are not always paid. There is then a risk of their instrumental use. However, living labs are often not very explicit on these problems [START_REF] Berthou | Les Living Labs, ces leviers d'innovation en santé publique[END_REF].

They nevertheless pay attention to bring value to each their stakeholders. The success of living labs depends on their ability of transferring knowledge between the different partners.

Based on the example of a French rural living lab, Fasshauer and Zadra-Veil (2020) highlight the value produced for the main categories of stakeholders (see Table 3). Beyond the sharing of the value among stakeholders, some living labs ambition is to disseminate the knowledge to external actors. Then, since ideas are shared within a large network of actors, the risk of recuperation by external actors is real.

All of these issues can be addressed through the establishment of governance mechanisms. This is all the more crucial that most research on the business models of living labs highlights the need to secure lasting collaborations (Garcia-Guzman et al., 2013[START_REF] Grezes | Embedding Business Model for Sustainable Collaborative Innovation in African Living Labs[END_REF][START_REF] Leroy | Living labs as engagement models for innovation[END_REF][START_REF] Niitamo | State-of-the-art and good practice in the field of living labs[END_REF] with numerous and heterogeneous actors. Living labs governance is challenging because they cannot directly manage or control stakeholders but rather just motivate them to engage in innovation activities (Bergvall-Kareborn and Stahlbrost, 2009). Governance is then a key for assessing sustainability. Indeed if actors perceive that a given project has resulted in unfair value realization across contributors, they are likely to exit that project or refrain from engaging in future projects [START_REF] Chesbrough | Value creation and value capture in open innovation[END_REF].

Methods: Exploratory study on 9 living labs

To study the business models of living labs, we first chose to focus on one country, France.

Indeed, the importance of public funding may suggest that there are significant differences among countries.

France is, with Spain, a country with the most ENoLL members (23 according to the web site as at August 2020), which is an indicator for the vitality of living labs in this country, even if many living labs do not belong to this network. In France indeed there are two competing local living lab networks: a network for Francophone living labs, which is strongly related to ENoLL

Network and a network dedicated to healthcare living labs (Forum LLSA).

We have developed a survey on the different dimensions of economic models identified by the literature.

Our survey thus presents a mixture of open and closed questions on six headings:

- In the absence of a global study and even a global database on living labs, it is impossible to decide on the representativeness of the sample. For example, health labs are very strongly represented (6 over 9). This may be linked to the fact that they are grouped into a specific network in France (forum LLSA) and therefore more easily identifiable.

The answers of the surveys were coded according to the different stakeholders that were addressed by the living lab activities (project's holders, local authorities, users, researchers)

The data analysis were structured in two steps:

1) A first level of analysis were made question by question in order to determine the similarities and the divergences.

2) A summary for each living lab has been written in order on the one hand to determine the nature of the generated value and on the other hand to observe if the different dimensions (value generation, revenues, value sharing and governance) were correlated.

Answers to the survey have been checked with secondary data, especially the websites of the nine living labs.

This analysis served as a basis for the constitution of proposals that will have to be tested in a further step of the research.

3.

French living labs business models

Value generation

Paradoxically, finding the nature of the value generation is the most difficult question to tackle. The creation of value is above all a response to customer needs. But it is very difficult to define who is the client of a living lab whose particularity is to bring together heterogeneous stakeholders. A living lab is not a commercial structure and the outcome of the innovation is commercialized by the project's holder. Thus the value provided by the living lab does not necessarily correspond to the value of the innovation for which it has sometimes only been an intermediary.

One of the living labs (A) considers that it provides research and public service work and that as such it has no customers. For the others, if the users are at the heart of the living labs project, Indeed a living lab is not dedicated to serve the needs of one specific category of customer but

is supposed to answer to the needs of all ist heterogeneous stakeholders. Understanding the generation of value therefore requires knowing the living lab network and the needs expressed by the various stakeholders, and understanding its objectives and activities.

All living labs claim to have more than three different categories of stakeholders: companies (8 living labs), not for organizations, local authorities, users (7 living labs for each of these categories), other public institutions (6), citizens (5) and hospitals (4).

The living labs also declare a great diversity in their activities, even if most of them perform activities all along the innovation process (from exploration to valorization). Two main activities emerge from the survey: the animation of the collaborative research process and the evaluation of the proposed solutions. These two activities meet the needs of almost all categories of stakeholders.

More generally, the answers to the question to which needs they answer, all living labs mentioned needs from projects'holders, some of them to users' needs or local authorities needs.

The means of production are often sketchy. Seven living labs have their own premises (D as owner, B, C, H and I are tenants for a fee while A and G are tenants for free). E and F operate without their own premises. Three living labs (A, D) have no employees but can rely on permanent staff from the supporting structure, G only works with volunteers, E, F, H and I declare between one and two salaried while B and C each declares ten. When there are employees, they perform commercial functions (search for partnerships), lobbying. They manage projects, contribute to research activities or to the provision of services. They are also in charge of the animation of the living lab.

Technical equipment is not widespread. Only four living labs (A, C, D and H) are equipped with technical platforms, either on its own or with their partners.

To characterize the value generation, it is also interesting to identify the main objectives declared by each structure. To this question, three living labs (A, C and I) put forward research objectives, E declares exclusively economic objectives (turnover) while the other five have a mixture of social objectives (improvement of the conditions of life) and economic (allow local small and medium enterprises and artisans to develop their offer towards the target audience).

In spite of having only 9 living labs in our sample, our survey proves that living labs can have very different structures and practices. The most significant findings relates to the main objectives of the living labs with three main categories of value generation: new knowledge, social value and economic value. Social and economic value appear on all living labs but the focus is put on one of these two dimensions (social for B, D and G; economic for E, F, H) or even a third one, i.e research for A, C and I.

Value remuneration

The question of remuneration for value arises all the more since no living lab sells the innovative product itself. Selling the innovation is generally the responsibility of the project owner (client companies).

The remuneration therefore relates either to the service offered for a particular project, or to the structure itself. In both cases, it is likely to mix public and private income as shown in Table 5.

Table 5: Sources of revenues declared by living labs (number of concerned living labs)

Revenues related to the structure

Revenues related to individual projects

Public funding

European grants (5)

Other public grants (8)

Public tenders (6)

Private funding

Partnership with not for profit organizations, foundations (2)

Invoicing of services ( 7)

Long term funding is necessary to ensure the sustainibility of living labs (Guzman et al., 2013).

Indeed long term funding often proves to be insufficient and living labs tend to compensate by a set of solutions, which are mostly short-term fundings like the answer to public tenders or the development of an offer of service. This is time consuming, all the more that living labs have only limited staff. Moreover public tenders are not always in adequation with the initial goals of the living labs. In conclusion, sources of revenues partially take into accound the hybrid nature of the value generation but are not always sufficient for ensuring sustainability.

Value sharing

None of the living labs remunerates users. The sharing of value therefore has no monetary character for this audience.

If D declares that it did not start any particular reflection on the sharing of value, the others consider that it is a problem without having found a satisfactory solution. They tend to adopt a pragmatic approach, with case by case decisions depending on the project.

One living lab protects certain innovations by patents or copyrights which in this case are carried by its affiliated entities. A second one uses Creative Commons licenses where possible and a third one systematically promotes open source. The others have no protection processes but have a specific concern for facilitating a large dissemination of the projects or the sharing of knowledge, skills or good practices. Globally, the focus is more on value sharing than on value capture. The value sharing is often claimed as one of the main targets of the living labs, either restricted to the members of the living lab or fully open.

Governance and inclusion of users

Seven living labs have a board of directors and only two do not have any specific governance structure. When there is a board of directors, it contributes to the definition of the strategy in connection with the management of the living lab and the parent structures. Four living labs (A, G, H and I) claim to include all members to participate into the definition of the strategy.

If only two living labs have set up a formal selection committee, six living labs have a project selection procedure based on defined criteria such as:

-Their suitability for the purpose of the living lab -Their scientific interest -The expected benefits for users -Feasibility (in financial or skills terms).

Users participate at all levels of the innovation process: ideation (A, B, E, F, G, H, I), prototyping (A, B, C, E, F, G, I) and test (A, B, C, D, E, F, G,H, I).

User involvement in projects seems logically to be a common practice but only some living labs include them in the governance of the structure. A kind of democratic governance (openness to all members) appears on four living labs out of nine.

Categorization proposal

Although the sample is quite small, this exploratory research allows us to propose a first categorization of living labs according to the main characteristics of their business model. This

proposal is shown in Table 6. The second category includes living labs that seek above all to have an impact on users (inhabitants of a rural area, elderly or disabled people). They cover needs that are poorly covered by both the public and private spheres while working in collaboration with public and private actors. The sharing of the value takes place through a desire for dissemination to a wider audience and transferability.

The third category includes living labs that seek above all to create a local economic ecosystem.

Their objectives are essentially economic and the sharing of value takes place mainly through the exchange of good practices within the network.

There seems to be a strong relationship between the nature of the generated value and the value capture or sharing. The other dimensions (revenues, governance) seem on the contrary to be independent and not related to the type of living lab. Although the sample is relatively small, it shows a variety of practices.

DISCUSSION AND CONCLUSION

This exploratory research contributes both to living labs and to open innovation literature.

As regards living labs literature, it proposes a description and a categorization of living labs business models.

We set up common dimensions of living labs' business models and we highlight three different forms of living labs depending on the nature of the generation of value: knowledge creation, social innovation and local network oriented.

These three categories rely on two interrelated dimensions: value generation and value sharing.

We identify three categories of value generation: knowledge creation, social value creation and business value. In fact the three different natures of value generation are almost always present in the different living labs but the main goals of the living lab is more focused on one or the other component. At this stage of the research there seems to be a relation between value generation and value sharing. Research oriented living labs have the most elaborated processes to protect value. For the other ones, there is a concern for taking into account the collective nature of the created value but they hardly find ways to formalize it. They nevertheless try to ensure a large dissemination of the innovation when it brings social value. At least they share the generated knowledge within the living lab network.

With few exceptions, the revenues are a mixture of public and private funding independently of the type of living lab. They seem to respond to opportunities rather than to deliberate strategies as we did not find any correlation between funding and type of living lab. The main reason is probably that living labs suffer insufficient criteria for assessing their performance [START_REF] Schaffers | Living Labs for cross-border systemic innovation[END_REF]. More especially, identifying or measuring the social value of living labs remains a problem, even if some researchers [START_REF] Gualandi | Models for Living Lab's Sustainability. Evidences from Italy and the Netherlands[END_REF] or institutes (Institut Godin in France) are starting to develop methodologies to assess the social value which is created. It is an avenue for future research which could then focus on the measurement of externalities.

Due to the numerous stakeholders, governance is always collective but in some cases there is in addition a concern for creating the conditions of a democratic governance, also independently of the nature of the living lab. Governance is in fact what the living lab will use to make choices on the creation and on the sharing of value by taking into account the variety of its stakeholders, including the user.

The proposed categorization differs from the one proposed by [START_REF] Leminen | Living Labs as open-innovation networks[END_REF] and [START_REF] Leminen | Coordination and participation in living lab networks[END_REF]. Even if the dominant actor is important for understanding the business model of living labs, other factors have to be taken into account. Indeed only their "provider" category is fully in line with our category "research oriented". Utilizer and Enabler categories may by either social innovation oriented or local network oriented.

It confirms that not only the outcomes of innovation are linked with the characteristics of the living lab [START_REF] Leminen | Categorization of innovation tools in living labs[END_REF] but also the value sharing of the innovation.

Moreover neither activities and structures nor governance of living labs seem to be related to the dominant actor.

Our research neither does not confirm the results of Leminen 2013 regarding the dominant coordination (bottom-up or top-down). The governance of living labs also includes lateral coordinations that are not taken into account by [START_REF] Leminen | Coordination and participation in living lab networks[END_REF]. A trend to more open and democratic governance is outlined by [START_REF] Habib | Living Labs as Innovation Platforms[END_REF] in their definition of third-generation living labs defined as "platforms with shared resources, which organize their stakeholders into a collaboration network, that relies on representative governance, participation, open standards and diverse activities and methods to gather, create, communicate and deliver new knowledge, validated solutions, professional development and social impact in real-life contexts". This is not the case for most of the living labs in our survey.

This research also contributes to open innovation literature which is dominantly focused on business models developed by industrial firms. The open innovation literature clearly calls for more research involving an organizational level of analysis, explicitely referring to the organizational designs and practices that underlie openness [START_REF] Ayerbe | Management Innovation and Open Innovation: For and Towards Dialogue[END_REF]. [START_REF] Chesbrough | Explicating open innovation: Clarifying an emerging paradigm for understanding innovation[END_REF] already extended the concept to public and not for profit organizations. We here focus on open business models for open innovation intermediaries, which allow to exit the "firm centric approach" of dominant open innovation researches [START_REF] Saebi | Business models for open innovation: Matching heterogeneous open innovation strategies with business model dimensions[END_REF]. Living labs present a new form of structure being able to "organize for open innovation" [START_REF] West | Leveraging external sources of innovation: a review of research on open innovation[END_REF] and remain largely beyond the well-acknowledged Open Innovation literature [START_REF] Hossain | A systematic review of living lab literature[END_REF].

The success of open business models is defined by aligning value creation and capture activities to an innovation [START_REF] Chesbrough | The logic of open innovation: managing intellectual property[END_REF][START_REF] Zott | The business model: recent developments and future research[END_REF]. This research shows that in living labs there is no mandatory alignment between value creation and capture mechanisms, even sometimes no real research of value capture. They mainly focus on value sharing, either restricted to the members of the living lab or fully open with an intention to widely disseminate the innovation. Sharing the value is thus one strategy to manage the openness paradox. This strategy is nevertheless not formalized, which may be due to the emergent property of living labs. This is thus made possible only as long as there is trust between the stakeholders and fairness and transparency in the decision process which allows the emergence of case by case solutions but raise the problem of sustainability.

This research is mainly limited due to the small sample and the fact that it is concentrated on only one country. It is also limited due to the use of the survey methodology which does not allow to understand the detail of the governance, the motivations of the diverse stakeholders and the value sharing mechanisms. This would be important to add deeper interviews with a variety of stakeholder for each living lab. An international comparison could also be useful to highlight the country specificities, especially as regards the sources of revenues.

Figure

  Figure 1: The four dimensions for studying living labs business models

  sent by email to 50 living labs, identified on the websites of the living labs networks: European Network of Living Labs (ENoLL) and the Forum of the Health and Autonomy living labs (LLSA). Nine structures have responded to date. Their main characteristics are summarized in Table4.

  they are not always the direct customers. Only two living labs declare having patients or individuals for clients (D and F). Otherwise their main customers are SMEs (B, C, D, E, F, G, H), large companies (B, C, E, F, G), not for profit organization (B, C, E, F, G, H) and local authorities (B, E, F, G, H), research laboratories (B, D, F, H), other public institutions (C, F, H).

  The first category includes living labs which are linked to universitary hospitals or research organizations and have objectives in terms of scientific publications. Their objectives are expressed in terms of innovation and / or publications. Nevertheless, they pay close attention to the needs of users and work in collaboration with projects'holders to produce innovation.They are the only ones to have formalized intellectual property practices, sometimes inspired by open source. They affirm a desire to disseminate the innovations to which they contribute on a large scale.

Table 1 : Categorization of living labs according to the driving actor (from Leminen et al., 2012; Leminen, 2013) Type of living labs Utilizer-driven Enabler-driven Provider- driven User-driven

 1

	Purpose	Strategic R&D	Strategy-devel-	Operations de-	Problem-solv-
		activity with	opment through	velopment	ing by collabo-
		preset objec-	action	through in-	rative accom-
		tives		creased	plishments
				knowledge
	Dominant ac-	Companies who	Public-sector	Educational in-	User-communi-
	tor	launch a living	actors, non-gov-	stitutes, univer-	ties
		lab to promote	ernmental or-	sities, or con-
		their business	ganizations, and	sultants.
			financers, that
			pursue societal
			improvements.
	Outcomes	New knowledge	Guided strategy	New knowledge	Solutions to us-
		for product and	change into a	supporting oper-	ers'everyday
		business devel-	preferred direc-	ations develop-	life problems
		opment	tion	ment
	Coordination	Top-down	Bottom-up	Top-down	Bottom-up

Table 2 : Potential revenue sources for living labs Public/Private Origin of funding Nature of revenues

 2

	Private	Customer	Payment for products or ser-
			vices
		Private companies	Donations and sponsoring
			Membership fees
			Invoicing of annex services
			(workshops…)
			Intellectual property, patents
	Public	European Union/ State/ local	Grant
		authorities
		State/ local authorities	Public order: calls for pro-
			jects or expressions of inter-
			est
	1.4.	Sharing the value, a question of governance?

Table 3 : Value creation by category of stakeholder for a rural living lab (Fasshauer and Zadra-Veil, 2020)

 3

	Stakeholder	Type of value generation
	Local authorities	Dialog with citizens
		Territorial attractivity
		Economic and social impact
	Firms/ not for profit organiza-	Better risk evaluation (small scale test)
	tions	Partnership
		Understanding of emergent needs
	Users	Opportunity to contribute to products and services
		adapted to their own need
		Access to knowledge and competences
		Social relationship

Table 4 : Short presentation of the nine living labs Living lab

 4

		Date of	Legal structure Category	Activity sector	ENoLL
		creation		(Leminen,		membership
				2012)
	A	2002	Department of	Provider	Healthcare	No
			University		(gerontechnologies)
			hospital
	B	2009	Groupment	Enabler	Healthcare	Yes
			around a public		(Autonomy)
			regional
			structure
			(groupement
			d'intérêt public)
	C	2010	Foundation	Provider	Healthcare	Yes
			(related to		(gerontechnologies)
			university
			hospital)
	D	2010	Department of a	Utilizer	Healthcare	No
			mutualist		(autonomy)
			organization
	E	2011	Cluster	Utilizer	Healthcare	No
					(gerontechnologies)
	F	2015	Not for profit	Enabler	Healthcare (medico-	Yes
			organization		socioeconomic
			(mainly created		innovation)
			by public local
			actors).
	G	2010	Not for profit	User	Rural development	Yes
			organization
			(created by
			citizens)
	H	2014	Not for profit	Utilizer	Digital innovation	No
			organization
			(created by
			entrepreneurs)
	I	2011	Cooperative	Provider	Design of new	Yes
			(SCOP)		services using
					satellite data

Table 6 : Categorization proposal

 6 Values that guide the choice of partners and projects -An importance given to the user who participates in the different phases of the innovation -A desire to recognize the importance of the collective nature of the value created

	Type of living lab	Research oriented	Social innovation oriented	Local network ori-ented
	Number living labs	of	3	3	3
			-A vast network of heterogeneous partners (companies
			of all sizes, public institutions, not for profit organiza-
			tions, individuals, etc.)
			-Attention to the needs of projects' holders
			-Mixed private / public income
	Common		-Low workforce (between 0 and 10 employees)
	dimensions		-Collegial governance
	New knowledge -Nature of the generated value (not excluding eco-nomic and social va-	Social value first, economic value sec-ond	Economic value first, social value second
			lue)
	Value sharing		Dissemination + in-tellectual property protection	Dissemination/ transferability	Sharing knowledge within the network

Inhalation-dominated approach refers to the ability of the driving actors to enroll the network in their own innovation activities and targets(Leminen,

2013). The exhalation-dominated innovation approach meets on the contrary the needs of the other participants. The driving actor then expects indirect benefits.