Keywords: Communication, Environmental policy, PCB pollutions, risk assessment, social problems, temporal patterns

discourse and then understanding the temporal patterns of information.

How Chemical Pollution Becomes a Social Problem.

Risk Communication and Assessment through Regional Newspapers During the Management of PCB Pollutions of the Rhône River (France).

Emeline Comby, Yves-François Le Lay et Hervé Piégay

ABSTRACT

The case study of the polychlorinated biphenyl (PCB) pollutions of the Rhône River (France) offers the possibility of studying criteria for the construction of social problems that result from chemical pollution (2005)(2006)(2007)(2008)(2009)(2010). We investigated the dynamics of competition that create and define pollution as a social problem and entail its decline. News outlets are crucial for determining how an environmental issue emerges locally or nationally; this study used newspapers to highlight the potential of new outlets as a data source to analyze discourse variability, science-policy-media connections and the hydrosphere. Media coverage was based on a content analysis and textual data analysis of 75 articles. Analytical frameworks such as the Downs Model and the Public Arena Model [START_REF] Hilgartner | The Rise and Fall of Social Problems: A Public Arenas Model[END_REF]) that consider time and stakeholders were tested to determine how human alteration of the hydrosphere can become a social problem and to analyze different communication strategies held by stakeholders. In terms of management, we described the temporal dynamics of the social problem based on the case study and considered an explanation of the selections. We considered the organization of particular stakeholders who define the social problem from its beginning to end by focusing on their discourses, relationships, decision-making and political choices, and scientific studies. Despite some biases, newspapers are useful for retrospectively evaluating the emergence of a social problem in the public arena by describing it through

INTRODUCTION

As explained by [START_REF] Smith | Climate change in the British press: the role of the visual[END_REF], three information sources contribute to the public knowledge of environmental issues: experience, social links, and media. The majority of the public depends on media information because they cannot experience the whole of reality [START_REF] Lacey | The Press as Public Educator[END_REF]. The influence of one media source on the public cannot be determined because of the complexity and number of daily messages received [START_REF] Wahlberg | Risk perception and the media[END_REF]. Among media sources, newspapers can be an interesting source of information in the retrospective analysis of socio-environmental contexts. Because newspapers are part of the daily lives of their readers, they are an element that can mold the relationship between people and their environment [START_REF] Waitt | Media Representation of Forestry and Soil Issues in the Australian Urban Press, 1990-1991[END_REF], construct public discourse, and shape the public perception of risk [START_REF] Ferreira | Risk, transparency and cover up: media narratives and cultural resonance[END_REF].

Disasters and catastrophes are typical environmental issues of interest to newspapers [START_REF] Allan | Environmental risks and the media[END_REF]Committee on Disasters and the Mass Media, 1980;[START_REF] Hansen | Environment, media and communication[END_REF][START_REF] Lester | Media and environment: conflict, politics and the news[END_REF][START_REF] Pantti | Disasters and the media[END_REF][START_REF] Sandman | Environmental Risk and the Press: an explanatory assessment[END_REF], and media events consider unusual, unexpected, and emotional threats towards human life and property [START_REF] Salomone | A Question of Quality: How Journalists and News Sources Evaluate Coverage of Environmental Risk[END_REF] or add personalization, dramatization, and novelty [START_REF] Boykoff | Climate change and journalistic norms: A case-study of US mass-media coverage[END_REF]. [START_REF] Wakefield | Constructing the News: The Role of Local Newspapers in Environmental Risk Communication[END_REF] studied risk through newspaper reports and stated that scientific interest is doubled if (a) newspapers can teach researchers how to communicate issues regarding risks, and (b) highlight the characterization of the public perception of risk. Through local exploration, the media provides information concerning risks to inform citizens and to influence the acceptability of risk [START_REF] Bakir | Media and risk: old and new research directions[END_REF]. Newspaper discourse on disaster may provide a basis for assessing a number of research assumptions that consider the media framing of disaster news and the role of newspapers in risk communication and hazard perception [START_REF] Rashid | Interpreting flood disasters and flood hazard perceptions from newspaper discourse: Tale of two floods in the Red River valley, Manitoba, Canada[END_REF].

Nevertheless, as [START_REF] Mccomas | Telling Stories About Global Climate Change Measuring the Impact of Narratives on Issue Cycles[END_REF] indicated, media attention and public attention cycles are linked, even though this contribution is not centered on public reception of media messages. If newspapers cannot tell readers what to think specifically [START_REF] Rogers | The Anatomy of Agenda-setting Research[END_REF], they can tell readers what to think about generally. Following this idea, we may ask how an environmental issue emerges in public debate. For [START_REF] Downs | Up and down with ecology: the "Issue-Attention Cycle[END_REF], these issues are illustrated by the ups and downs in attention cycles that result from the following three features: (a) problems that influence a few players who are suffering, whereas the majority do not face these difficulties; (b) problems that are generated by social arrangements that provide significant benefits to a majority and a powerful minority of the population; and (c) problems that do not have intrinsic qualities, regardless of whether they cease to exist. From a constructionist approach, certain socio-cultural factors may explain the establishment of ups and downs in the media coverage of environmental issues because of their use of narratives [START_REF] Mccomas | Telling Stories About Global Climate Change Measuring the Impact of Narratives on Issue Cycles[END_REF]. Moreover, [START_REF] Hilgartner | The Rise and Fall of Social Problems: A Public Arenas Model[END_REF] wanted to move beyond this type of "natural history model" (p. 54), which considers idealized descriptions that result from the absence of complex temporal patterns and interactions among problems.

Social problems must compete for social attention at two levels: to win against other problems and to be characterized among all given definitions of this problem. A social problem is "a putative condition or situation that is labeled a problem in the arenas of public discourse and action" (Hilgartner and Bosk, 1988, p. 55). Figure 1 shows how we apply this theoretical framework to our analyses. A newspaper may be viewed as an efficient public arena as the social problem evolves over time and provides different possibilities of feedback (problemamplifying or damping). Certain topics are placed in the foreground by newspapers and may assist in the understanding of the science-policy-media connection and media concerns. [START_REF] Mccombs | The Agenda-Setting Function of Mass Media[END_REF] considered that media focused on crucial issues during political campaigns and consequently "set the agenda for each political campaign, influencing the salience of attitudes toward political issues" (p. 177). If media coverage does not directly include policy decision making, it may shape the possibility for political engagement [START_REF] Boykoff | Who Speaks for the Climate?: Making Sense of Media Reporting on Climate Change[END_REF].

Following [START_REF] Leiss | Effective risk communication practice[END_REF], an effective risk communication effort concerning major public controversies such as chemical pollution requires a) a "science translation" (p. 399) that will be given in clear and comprehensible language, b) a qualitative and quantitative description of uncertainties, and c) an interface between science and policy. To explore how information is discussed and how science interacts with media and policy when a pollution problem is emerging, we selected a critical event: the polychlorinated biphenyl (PCB) pollutions of the Rhône River from 2005 to 2010, which was considered a disaster by a large set of stakeholders with a regional extent and entailed a national management scheme. We aim to explore the temporal patterns of discourses and stakeholder involvements with a regional newspaper, Le Progrès (considered a public arena), when there are concerns for pollution that is considered a social problem. The following questions are addressed: i) When should stakeholders communicate based on the public's needs; ii) Despite scientific uncertainties, what type of information is spread and what types of decisions are made; and iii) How has scientific research been translated to the public, while comparing different public arenas?

SPATIAL AND TEMPORAL CONTEXT

The Rhône River drains a catchment area of 98,000 km² in southeastern France. It has a 512 kilometer main stem downstream of Lake Geneva and flows to the Mediterranean Sea (Figure 2). Its valley is occupied by large urbanized areas: Lyon, Valence, Montélimar, Orange, Avignon and Arles. From 1948 to 1986, nineteen dams were constructed to produce hydroelectricity, to aid in navigation and to irrigate land areas. Four nuclear power plants use water from the Rhône River to cool reactors. This valley is one of the major French axes for transport (highways and high-speed railroads).

Our study addresses the period from 2005 to 2010; pollution was discovered in the mideighties but appeared to be neglected for over twenty years. During the mid-eighties, researchers were helped through a regional environmental NGO (Fédération Rhône-Alpes de Protection de la Nature -FRAPNA -for Rhône-Alpes Federation for nature protection), which revealed and studied this pollution. After two European Frameworks in 1976 and 1985, the use of PCBs was prohibited in 1987 in France (Figure 3). In 1996, the Council of the European Union planned PCB decontamination in different countries. France reacted too late and was condemned in 2002 because its action was too weak. In 2006, a European Commission Recommendation updated the Regulation N°466/2001 and the Recommendation 2002/201/EC, and issued reductions of the presence of dioxins, furans and PCBs in feedingstuffs and foodstuffs to limit human exposure to these chemicals [START_REF] Ec | Commission Recommendation of 6 February 2006 on the reduction of the presence of dioxins, furans and PCBs in feedingstuffs and foodstuffs[END_REF]. In France, this recommendation entailed the nationwide monitoring of freshwater fish contaminated by PCB congeners [START_REF] Babut | Nationwide PCB congener pattern analysis in freshwater fish samples in France[END_REF].

After a peak in scientific interest (for example [START_REF] Monod | Effects of chemical pollution on the activities of hepatic xenobiotic metabolizing enzymes in fish from the river Rhône[END_REF] and public attention at the end of the eighties, the PCB pollutions of the Rhône River drew no attention until 2005. In 2004 in the Grand Large, many dead birds were found and fishing was forbidden. The analyses showed that the death of birds was a result of avian botulism, and fishing was no longer prohibited. However, a fisherman had to reassure his main customers regarding the quality of fish, and in March 2005, he requested more complete analyses (Figure 2). Until September 2005, water authorities did not divulge evidence of pollution, particularly to the media, whereas scientific research was led by the DDASS (Departmental Services about Health and Social Affairs). The Rhône was the first river in France affected by the discovery of PCB pollutions. After the Rhône pollution was detected, other cases were discovered, such as in the Seine or Loire rivers.

On the 14 th of September, 2005, the Préfecture (departmental administration) prohibited the consumption and marketing of fish from the Canal of Jonage (Figure 2). From February to August 2007, this interdiction spread from Sault-Brénaz to the Mediterranean Sea. However, in May 2008, the Drôme, Adèche, Gard, and Vaucluse departments reduced the prohibitions (Système d'Information sur l'Eau du bassin Rhône-Méditerranée, 2013), and they were only concerned with benthic species (Anguilla anguilla, Abramis brama, Blicca bjoerkna, Barbus barbus, Silurus glanis, Cyprinus carpio, etc.) and migratory fish (Alosa fallax rhodanensis, Lampetra fluviatilis, Lampetra planeri, Petromyzon marinus, etc.). These departments were Thanks to a national scheme, new scientific programs were implemented (Figure 3) that focused on the concentrations of PCBs, the transfer of PCBs from sediment to fish [START_REF] Lopes | Transfer of PCBs from bottom sediment to freshwater river fish: A food-web modelling approach in the Rhône River (France) in support of sediment management[END_REF], and the necessity of determining a sediment quality guideline [START_REF] Babut | BSAFs for freshwater fish and derivation of a sediment quality guideline for PCBs in the Rhone basin, France[END_REF].

The collection of freshwater fish was performed by professional fishermen (including the fishermen who need to find a new job because of interdictions) and technicians from fish management authorities [START_REF] Babut | Correlations between dioxin-like and indicators PCBs: Potential consequences for environmental studies involving fish or sediment[END_REF]. Different institutions (including DDASS, Afssa, and Anses) tried to understand the PCB pollutions and the fish contaminations, considering more and more individuals from two fish in 2005 to 643 in 2009 [START_REF] Afssa | Avis de l'Agence française de sécurité sanitaire des aliments relatif à l'interprétation des résultats d'analyses en dioxines et PCB des poissons pêchés dans le fleuve Rhône dans le cadre du[END_REF], and more and more species [START_REF] Afssa | Avis de l'Agence française de sécurité sanitaire des aliments relatif à l'interprétation des résultats d'analyses du plan d'échantillonnage mis en place dans le cadre de la pollution en PCB des poissons du Rhône[END_REF]2008). Two classes of PCBs could be distinguished because of their toxicological properties: the dioxin-like PCBs (DL-PCBs) which show analogous toxicity as dioxin compounds and the non-dioxin-like PCBs (non-DL-PCBs) [START_REF] Blanchet-Letrouvé | Dioxin-like, non-dioxin like PCB and PCDD/F contamination in European eel (Anguilla anguilla) from the Loire estuarine continuum: Spatial and biological variabilities[END_REF]. The Rhône analyses dealt with PCBs (e.g. DL-PCBs as well as non-DL-PCBs), and PCDDs [START_REF] References Afssa | Avis de l'Agence française de sécurité sanitaire des aliments relatif à une demande d'appui scientifique et technique relative au risque sanitaire lié à la consommation de poissons pêchés dans le département du Rhône (zone du canal de Jonage[END_REF]. A national database on fish contamination by polychlorodibenzo-dioxins (PCDDs) and related compounds [START_REF] Babut | Nationwide PCB congener pattern analysis in freshwater fish samples in France[END_REF] was created, thanks to the investigations of three hundred and thirteen sites. As the PCDDs are lower than European thresholds, the researches focused on risk assessment of PCB concentrations (Table 1). Understanding the factors affecting fish contamination appears to be necessary to assess health risks to upper-trophic level consumers (including human beings) [START_REF] Lopes | Is PCBs concentration variability between and within freshwater fish species explained by their contamination pathways?[END_REF].

The levels of PCBs become a topical issue with a high scientific interest : if Oliveira Ribeiro et al. ( 2005) dealt with organochlorine pesticides, polycyclic aromatic hydrocarbons, and heavy metals in the eel (Anguilla anguilla) in the Rhône Delta, at the Camargue Nature Reserve, their fish collection (thirty eels) of October 2003 was used a few years later to study bioaccumulation of polychlorinated biphenyls in the eels [START_REF] Oliveira Ribeiro | Bioaccumulation of polychlorinated biphenyls in the eel (Anguilla anguilla) at the Camargue Nature Reserve -France[END_REF]. In France like in many European countries PCB levels in eel are at levels of concern: PCB levels are often higher than in other species [START_REF] Geeraerts | The effects of contaminants in European eel: a review[END_REF].

Although [START_REF] Santiago | Nutrient, heavy metal and organic pollutant composition of suspended and bed sediments in the Rhone River[END_REF] showed that the occurrence of pollutants increased dramatically downstream from Lyon, new analyses were performed by using sedimentary archives: PCB concentrations were linked to an upstream-downstream pattern because of different drivers (floods, flushing events, tributary contaminations, populations, and the small amounts released by PCB treatment facilities) [START_REF] Mourier | Historical records, sources, and spatial trends of PCBs along the Rhône River (France)[END_REF]. [START_REF] Desmet | Spatial and temporal trends in PCBs in sediment along the lower Rhône River, France[END_REF] noted that PCB concentrations decreased in the mid-nineties but remained relatively stable afterwards. No additional hot spots of contaminations were found, but studies highlighted the diffuse, significant, and often unknown sources of pollutions that corresponded to 307 kilograms of PCBs released to the Mediterranean Sea from 2008 to 2011 [START_REF] Pradelle | Évaluation des sources contributrices au flux de PCB du Rhône à la Méditerranée[END_REF] (Table 2).

METHODS

Collecting a Corpus of Regional Articles

Le Progrès, which is edited, published and printed by a company in Lyon, was the daily newspaper chosen for this study. It is the fifth-largest regional newspaper in France based on sales and is the first newspaper upstream of the Rhône with approximately 250,000 papers sold per day. Its main reader base (more than 700,000 readers) is shown in Figure 3. This newspaper was the first local edition (Lyon metropolitan area with more than 50,000 sold items per day) to discuss the problem of PCBs in the Rhône. The first sick fish found was in its coverage area (approximately ten kilometers from the head office). A majority of the main stakeholders (including elected officials, professional and recreational fishermen, NGO members, and scientists) lived in its diffusion area, and this newspaper acts as a regional forum.

The archives of Sciences Po Lyon (Institute of Political Studies), located in Lyon (Rhône-Alpes), receive and archive this newspaper daily. One researcher thoroughly read all daily papers from January 1, 2003 to December 31, 2010 to select articles related to water issues in the Rhône River. Each article was photographed and catalogued as numerical data, and a database was compiled. Each article in the corpus was considered an individual piece for statistics and characterized by the following variables: publication date, author, page and mentioned actors.

The comparative analysis of different newspapers helped to strengthen the data, to evaluate the variability of opinions and debates, and to evaluate the biases of these sources. To discuss the results, we compared these newspaper articles with other regional newspapers from the downstream stretch and with one of the most powerful and widespread national newspapers, Le Monde. At a regional scale, we selected two different newspapers whose coverage areas were located in the middle and lower Rhône (Figure 2): Le Dauphiné Libéré, which is a regional newspaper that is the 4 th -most sold in France with a coverage area in Drôme and Ardèche, and La Provence, which covers an area of the downstream stretch (Avignon and Arles metropolitan areas). We wanted to study the spreading of this social problem in various areas fed by interactions between different public arenas through social networks and patterned institutions.

The raw material consisted of 674 articles focusing on the Rhône River, and pollution was the third-most mentioned question after leisure and waterfront redevelopment (Figure 4).

Seventy-five items were published on the Rhône pollution by PCBs, with 75 percent of the articles in the regional section (shared by all editions of Le Progrès), 21 percent in the national sections and only 4 percent in the local sections (in the Lyon metropolitan area).

Twenty-three percent of articles were on the front page, which illustrated the importance of PCB pollutions, and 9 percent were interviews revealing the role played by certain actors. A fifth of the articles were written by the same journalist who has great knowledge regarding all local stakeholders and the evolution of this type of pollution. Because these articles are not redundant, we used different analyses to aggregate their messages.

A Mixed Approach Combining Quantitative and Qualitative Analyses

Considering discourses as a social act, Fairclough (2010) adopted a three-scale approach: a micro-approach similar to linguistics; a meso-approach based on production, circulation and reception; and a macro-approach based on the social construction of discourse (production and reproduction in the society). We focus on the first aspect and also address the second issue. Peters and Hosgood (1985) suggested the creation of a quantitative analysis of issue salience. Our quantification entailed two different methods: a content analysis and textual data analysis. Berelson (1952, p. 18) defined content analysis as "a research technique for the objective, systematic, and quantitative description of the manifest content of communication." This descriptive method summarizes "the message set rather than reporting it in all of its detail" [START_REF] Boykoff | Who Speaks for the Climate?: Making Sense of Media Reporting on Climate Change[END_REF]Boykoff, 2007, p. 1194). After reading each article, some categories were created to summarize all of the information for each item [START_REF] Boholm | Risk and Causality in Newspaper Reporting[END_REF]. Text is considered as a network of meaningful objects that must be coded in a table [START_REF] Vasterman | A Model for Evaluating Risk Reporting: The Case of UMTS and Fine Particles[END_REF]. This standard method [START_REF] Moodie | Content analysis: a method for historical geography[END_REF] allowed comparisons between different texts [START_REF] Mckay | Observations on mass media reporting and individual motivation to obtain a flood inundation map-River Torrens, Adelaide, South Australia[END_REF], despite the studied articles showing variability. Nevertheless, the categorization and codes were qualitative phases, although codes could be treated through statistics [START_REF] Boholm | Risk and Causality in Newspaper Reporting[END_REF]. To study the 75 articles, we focused on specific explanatory facts regarding the nature of the pollution, consequences such as the location of the pollution and its impact on health and acts that regulate the crisis (Table 3). One person filled in a table with all qualitative variables for each article to limit the interpretation by the coder and to reduce inter-coder variability [START_REF] Maher | How and why journalists avoid the population-environment connection[END_REF]. Two modalities may occur at the same time so that we can study co-occurrences [START_REF] Boholm | Risk and Causality in Newspaper Reporting[END_REF]. Codes were assigned after reading each article [START_REF] Brossard | Are Issue-Cycles Culturally Constructed? A Comparison of French and American Coverage of Global Climate Change[END_REF][START_REF] Wakefield | Constructing the News: The Role of Local Newspapers in Environmental Risk Communication[END_REF], and statistical analyses were performed with the R software [START_REF] Ihaka | R: A language for data analysis and graphics[END_REF]. This study does not consider how messages are constructed or received but is rather focused on their content.

A discourse analysis was used to determine the role of words and discourse in constituting social practices and individuals from a post-structuralist perspective [START_REF] Phillips | Mediated Communication and the Privatization of Public Problems: Discourse on Ecological Risks and Political Action[END_REF]. To avoid the formation of categories used in the content analysis and bias through hasty interpretations by researchers, textual data analyses considered only written or pronounced words [START_REF] Lebart | Exploring Textual Data[END_REF]. Textual data analyses created in the 1970s were based on inductions and interpretations of statistical results of texts [START_REF] Benzécri | L'analyse des données. Analyse des correspondances. Exposé élémentaire[END_REF]. This technique has been improved through different statistical analyses [START_REF] Lebart | Exploring Textual Data[END_REF] and is called textometry, which combines factorial correspondence analyses with full-text search techniques. We used an open-source platform called TXM to perform our textual data analyses [START_REF] Heiden | The TXM Platform: Building Open-Source Textual Analysis Software Compatible with the TEI Encoding Scheme[END_REF]. For the "results" section, we combined these quantitative analyses with a qualitative approach through different quotations.

RESULTS

Temporal Signature of Pollution within Media Discourses: Dynamics of Direct Competition Considering Different Issues

The main issue associated with leisure and waterfront developments throughout almost the entire period, whereas pollution coverage underwent a specific bell-shape trend compared to other topics that were more constant in frequency through time or that had many ups and downs (e.g., nuclear power plants, dams, floods, etc.) (Figure 4). When considering the bellshaped trend of pollution topics, we found that the PCB issue was introduced abruptly. In 2003 and 2004, pollution was an infrequent issue for newspapers that dealt with the presence of heavy metals, which was a recurrent problem without any immediate solution; however, there was no mention of PCBs. Nevertheless, PCB pollutions became a topical issue after Twenty-seven percent of items only considered pollution from a regional approach from October 20, 2005, to May 26, 2007. Fifty-five percent of articles considered the whole Rhône corridor as polluted, and they were published from July 24, 2007, to the end of the period.

The number of published items indicated that this pollution was characterized by a specific temporal trajectory in media coverage (Figure 5). Since 2005, the role played by pollution showed a significant increase, which was confirmed in 2007 (Figure 5A and 5B) and based on 9 articles in 2005 and 2006 and 28 in 2007. After the peak in 2007, the number of articles decreased regularly (Figure 5A). In 2010, several articles were published, but the dynamics of the 2005-2007 period appeared to fade. Figure 5B focuses on the monthly scale and shows that the trajectory was not as smooth as shown in the annual focus with specific events provoking increased media attention. Until 2009, these events appeared to be less numerous.

Discourse Framework Characterizing an Environmental Pollution

The multiple correspondence analysis performed on the content analysis information at the scale of each article provided a similar synthetic temporal trajectory of the event as that explored by textometry (Figure 6), but it was also related to the topics of concern, pattern of discourse and rationale (Figure 7).

The first two axes represented 51.5 percent of the total inertia (Figure 7). The first factorial map was organized by the problem of diffusion through space and time and evolution of the concerned stakeholders. The negative coordinates on the first axis were structured at a local scale for the first two years of the period, whereas the positive coordinates were structured at the national scale for the last years of the period. The problem peak was shown in the negative coordinates on the second axis, which loaded 20.5 percent of the inertia and highlighted items characterizing this peak that were mainly linked to a negation of the pollution problem (negative coordinates) in 2007.

On the negative side of axis F1, the temporal period was from 2005 to 2006 and evoked the beginning of the pollution during the 2000s at the Lyon urban-area scale. The quoted stakeholders were journalists, professional and recreational fishermen, and water management institutions. The fault appeared to result from illegal contamination, unknown waste and Electricité de France (EDF, a national company that produces and distributes electricity): "no analysis was conducted after flushing-out operations" (09/16/2005). The uncertainty was high because of weak scientific studies. No geographic comparison was included, and the study area was either local or regional. The politicians either did not act at all or only acted at a local scale. The pollution may have had consequences on the water supply, irrigation, fish, trophic chain, and human health (for example, the risk of cancer).

On the neutral coordinates, an intermediate situation can be observed before the increased prohibition in the year 2007, and certain stakeholders (scientists, ecologists and companies) and impacts on angler activity were mentioned: "The Rhône River goes downstream […] but we buried our head in the sand" (02/24/2007).

On the positive side of the first axis between 2008 and 2010, the pollution was perceived at a national scale. Responsibilities were attributed to old uses that possibly dated back to the nineteen-thirties. The quoted stakeholders were politicians and members of the court. The entire fluvial corridor was polluted along with other rivers in France. The political actions were both regional and national, the health consequences were numerous and unknown, and additional impacts to leisure activities were induced. Concerning scientific research, there were contrasts between its absence, prominence, and equilibrium. Uncertainty associated with the pollution was weak or normal, and concrete projects were mentioned, such as the extraction of polluted sediments.

On the negative side of the F2 axis, we observed frequent pronounced discourses in 2007 that were organized around the absence of themes (such as production, recreation, environmental scale of pollution, health consequences, and scientific research), role of claims, court, and particular stakeholders, such as the members of the court and companies. The evoked historical period was the seventies. It is still not known exactly who the guilty party may have been. On the positive side of the F2 axis, we found a mixed discourse focused on who was responsible for the pollution, which included companies such Tredi, EDF, which managed the sediments, and illegal users. Certain stakeholders were quoted, such as scientists, water management institutions, and journalists. In the foreground, the weak uncertainty was explained by local contamination; impact of fishermen, anglers and leisure activities, no judiciary consequences; politician mobilization at a local or a regional scale; number of contaminated fish and hydrosystems; great number of health consequences; and scientific research in 2005, 2008, 2009, and 2010. Considering the causes analyzed through the content analysis, newspapers painted a progressive evolution of attitudes. Forty-two percent of the articles mentioned history to explain the current situation and evoked periods from the 1930s to 2000s, with a peak during the 1980s (21 percent of items): "Twenty years after the first contamination, two fish have the same symptoms" (09/16/2005). The company Tredi was most often quoted; it re-treated PCB waste and was accused of being a polluter. Nevertheless, no single guilty party could be found because the contamination occurred over such a long period and there was such a diversity of polluters. The quantification provided additional information regarding the stakeholders who were explicitly quoted; in 2005 and 2006, professional and recreational fishermen were first, followed by scientists and water managers. In 2007 and in 2008, politicians played a significant role during the peak of the media coverage and environmentalists, whereas scientists and professional and recreational fishermen played a secondary role. Since 2009, there has been a new equilibrium with politicians and courts.

We only focused on people whose names were the most quoted in the corpus (Figure 8

DISCUSSION

When Does Pollution Become a Topical Issue?

The understanding of temporal patterns of information enables us to propose strategies to different stakeholders to help them better respond to public interest at the right time, such as when concern over pollution increases.

For [START_REF] Anderson | Media, culture, and the environment[END_REF], an environmental issue became newsworthy when the coverage focused on an event, visual components and story that occurred less than 24 hours before. This framework does not completely correspond to the description of PCB pollution: (a) although there was no real event, the announcement of fish contamination and prohibitions on consuming fish can be considered major events; (b) when the pollution was not visually recorded, the newspaper communication was based on "toxic images" or "visual representations that are found in print or digital media of people, places, or toxins, which are used to make claims of human-produced contamination causing the degradation of the natural" (Peeples, 2013, p. 193); but (c) the diffusion of PCB pollutions dates back several decades and may still last a long time. These traditional characteristics of media interest have evolved because of the emergence of slow and long-term environmental processes such as global change [START_REF] Hansen | The mass media and environmental issues[END_REF].

The temporal pattern of media coverage may be divided into different steps. The Downs' Model (1972) [START_REF] Cram | Whither the Commission? Reform, renewal and the issue-attention cycle[END_REF] and may form the risk perception. Nevertheless, the Downs Model is a very simple representation of temporal patterns and may not help us understand reality at a finer time scale. The year scale is perhaps too broad to show how a social problem is formed [START_REF] Newig | Public Attention, Political Action: the Example of Environmental Regulation[END_REF]. Disaster and risk are characterized by a succession of sporadic levels of media attention and scenes in newspapers that are reanimated as new elements are introduced into the debate. Media coverage is not entirely absent after the peak, and new alarming news can reactivate it. Some new issues including leisure and waterfront developments that appear more topical: The competition is central to understanding the selection of social problems.

Despite Uncertainties, What Type of Information and Decisions Are Expected by the

Public?

We consider the importance of competition and selection in the context of the Hilgartner and Bosk Public Arena Model (1988). Figure 9 The decrease appears to be linked to the feeling that certain national policies may regulate this pollution and that while the problem may be widespread, it is not such a threat after all. PCB pollutions no longer concentrates this fear of the unknown [START_REF] Hansen | The mass media and environmental issues[END_REF] because of the partial possibility of answering the five Ws and one H: Who performed the polluting? What happened? When did it take place? Where did it take place? Why did it happen? and How did it happen? Therefore, the debate became somewhat dull. Because the problem might now come to an end as a result of political measures, the questions might arouse fewer emergencies.

There appears to be common points in the temporal patterns between media coverage of PCB pollutions and policies to fight the pollution. Politicians are citizens and consume information from the media; therefore, they may be shaped by it, which may influence their decisionmaking processes [START_REF] De Loë | Dam the news: Newspapers and the Oldman River Dam project in Alberta[END_REF]. Figure 8 shows that the most-quoted stakeholders are the actors of the top-down policy. Thus, politicians must be part of the primary definers, and they are followed by fishermen, environmentalists and scientists who may all have a discourse oriented towards preservation or protection of rivers. In our case study, journalists asked for showed that certain fish may be less contaminated than others because of different exposure to sediments from contaminated sites, the weight of the fish or its age [START_REF] Babut | Contamination des poissons et des sédiments du Rhône par les polychlorobiphényles[END_REF], the area of partial prohibition increased. This decrease of precautionary principles may be another explanation of the decline in media coverage. When the coverage reached an apogee at the end of 2007, a national action began that implicated a new stakeholder: the Minister for Ecology. Thus, on October 10, 2007, Nathalie Koscisuko-Morizet appeared at the Rhône River to announce a national policy (commission and research program) against the pollution of French rivers by PCBs. As soon as this policy was initiated, we noticed a downturn in media interest on the question of PCB pollutants.

If we cannot explain the nature of all of the links between science, media coverage and political regulations, we argue that (a) some players used newspapers to stay in the forefront at a national scale, such as the Minister of Ecology, and at a local scale, such as certain mayors or NGO members, and amplify the social problem through interviews; (b) the chronologies of media coverage and political decisions succeeded each other, with media coverage reaching a maximum when political choices were absent or weak and politicians were in the spotlight, whereas political measures were frequent and researchers exposed their results when media coverage declined; and (c) the importance of media coverage appears to influence the creation of new scientific programs and governmental structures and the visibility and legibility of acts. The media do not only focus on disasters that expose difficulties; however, they show the answers given by society and in particular by politicians: "The professional and recreational fishermen are keeping calm. They are not choosing revolution right away. But we must blow the whistle. The State has to discover the source […]. We must find the polluter to prevent the pollution from continuing" (09/26/2006, a recreational fisherman).

How Has Science Been Translated to the Public?

Following [START_REF] Leiss | Effective risk communication practice[END_REF], whose aim was to reduce the knowledge gap between experts and lay people over time, we assumed that an efficient risk communication was based on some quantitative expression of pollution understanding that was framed in qualitative terms.

The quantitative risk information produced key metrics but tried to translate them in terms that are comprehensible for non-expert audience. The journalist may use international cut-offs to help the understanding: "All of the studied fish have between 9 and 47 picograms of PCBs per gram of flesh and display the European thresholds of 8 picograms" (08/18/2006). We can notice a reference into a non-expert language to the 2006 European recommendation which set a threshold of 8 pg.g -1 wet weight for the toxic equivalent concentration in all fish species, except eels. In our case study, three types of research were mentioned: academic research with scientists who published the quoted papers and technical reports (Figure 3), environmentally committed research linked to worldwide or regional NGOs (WWF, Robins des Bois, or FRAPNA), and institutional research (DDASS, Afssa or Anses) that justifies the prohibition area. They both use e-media and their own internet websites to show their current results and future objectives. In June 2008, certain doctors (members of an environmentalist NGO called Association Santé Environnement Provence -ASEP) published the conclusions of an unofficial study on 52 people from the Lower Rhône: everyone was a PCB carrier, even people who never ate fish from the Rhône River. The presentation of the results was filmed and published by WWF on Dailymotion [START_REF] Wwf | Etude d'imprégnation aux PCB : Résultats[END_REF]. In January 2009, 150 riverside inhabitants of the Rhône River took part in a national study that analyzed the contamination of the population by PCB pollutions, but the results were only published in November 2011 [START_REF] Anses | Avis de l'Agence nationale de sécurité sanitaire de l'alimentation[END_REF]. This example about health is emblematic: People no longer had access to information, but may have been contaminated. The residents along the Rhône River may have all been victims, but no responsible party was declared guilty and no pragmatic solutions were found. Concerning decontamination, even though some scientific programs were initiated to handle address sediments, no solution appeared because it is expensive to remove all contaminated sediments and there is uncertainty concerning potential results.

The translation from technical and scientific terminology to a public-friendly language is based on a plot with emblematic stakeholders that resembles what can be found in narrative analyses [START_REF] Clandinin | Narrative inquiry: experience and story in qualitative research[END_REF]. We studied the stories as told by different stakeholders, such as the fisherman who is considered a main whistleblower and spoke to journalists about his experiences and the major turning point in the contamination discovery in a very dramatic way: "Two breams […] were enough to wake up muddy devils of the Grand Large reach" (09/16/2005). Over a period of five years, this fisherman produced a great number of interviews and decided to tell it as a story: "I'm waiting. I must now recover from this strain. Evidently, they don't finish sediment analyses. Anyway, I have no choice" (10/20/2005). Sixteen percent of articles related to PCB pollutions explained his life story and current situation because of this disruption. Following [START_REF] Kwan | Geo-Narrative: Extending Geographic Information Systems for Narrative Analysis in Qualitative and Mixed-Method Research[END_REF], we distinguished two types of history from retrospective and mediated perspectives: an oral history (consisting of personal thought to explain the causes and consequences of the pollution) and a life history (a biographic process to portray his entire life) in discourse. The newspaper focused on this fisherman's situation, although other fishermen were impacted. He symbolized one type of population that is directly affected: 18 percent of all published photographs depicting a human being present this fisherman in the foreground. Readers may be able to recognize him and consequently know that this article may explain to them the continuation of his story, such as in a serial. The construction of his narrative looks like a plot with an initial situation (everything seemed to be all right), disruption (the discovery of pollution), following events (the consumption prohibition, seriousness of pollution and insistence upon negative consequences), and potential resolution (through political choices, planned research and subventions in 2010). Since 2008, this fisherman has demanded the status of a sentry, which is a status defined in 2007 during the national Grenelle de l'Environment that tackled climatic and ecological crises in France and considered sustainable development as a national priority. This status exists but has never been applied. This fisherman wants to provoke national awareness concerning jobs, leisure activities or uses that make people realize environmental problems earlier than usual and must be recognized as a national utility: "Emergency subventions before kicking the bucket! […] I'm furious with the political exploitation of PCB pollutions during the last municipal election campaign" (03/16/2008). Because the focus of narrative analysis is not only on people's experiences but also the social, cultural, and institutional contexts of the construction of the problem, the media approach appears to use story-telling mechanisms and frames to communicate scientific information.

Finally, to understand public interest, spatial proximity with environmental issues may be a key, and geographic logic may be a result of the spatial diffusion of this pollution: Pollution is everywhere. The locations with high media coverage are scattered along the Rhône corridor and other polluted rivers. If the chosen newspapers put the upstream stretch in the foreground, the downstream stretch is not forgotten. The threatened Mediterranean Sea is often quoted and produces a broader perspective of the pollution case: "Perhaps the Rhône River pollutes the Mediterranean Sea" (08/18/2007). Because using just one newspaper may be biased and does not correspond to the high number of messages received each day, we compared our results with three others dailies. Le Monde did not publish any articles regarding this issue in the

CONCLUSION

Although the media is representative of only one perspective regarding the environment, which might appear biased, inaccurate and exaggerated [START_REF] Pasquarè | Geological hazards, disasters and the media: The Italian case study[END_REF], simplistic and guilty of polarizing arguments [START_REF] Vasterman | A Model for Evaluating Risk Reporting: The Case of UMTS and Fine Particles[END_REF], the present research highlights the temporal pattern of critical pollution and its spatial expansion related to a succession of discourses, issues and stakeholders. In terms of management, we showed that the life expectation of such a social problem is difficult to predict. Nevertheless, certain frameworks are useful for understanding the diffusion rationale and interactions between the media, science, and policy. An analysis focused on competition and selection principles appears to be able to explain the structure and organization of the newspaper data and therefore certain trajectories of the information, and the stakeholders and their relationships may entail media coverage. Following [START_REF] Boykoff | Who Speaks for the Climate?: Making Sense of Media Reporting on Climate Change[END_REF], we argue that "the media community serves a vital role in the communication process between science, policy and the public" (p. 28). When the social problem became prominent, new stakeholders, such as politicians, appeared and became crucial. More important media coverage inspires the rapid adoption of political regulations that may be undertaken at regional or national scales. Comparing different public arenas, we assumed that the same pollution entails a high variability of discourses in space and time because of problem-amplifying and problem-damping. These different public arenas can be delimited, but these limits seem blurred and in constant interactions; information spreads from one arena to another. It may explain why and how newspapers convert a seemingly long-term environmental problem into an imminent disaster.

LIST OF TABLES

Table 1. An overview of analyses led by the institutional research.

Table 2. The (unknown) contemporary sources of PCB pollutions (after [START_REF] Pradelle | Évaluation des sources contributrices au flux de PCB du Rhône à la Méditerranée[END_REF] at the Arles station from 2008 to 2011. The sum corresponds to the seven indicator congeners (∑iPCB). [START_REF] Hilgartner | The Rise and Fall of Social Problems: A Public Arenas Model[END_REF]. The success, size and scope of a social problem are linked with the amount of attention deployed by these arenas. The competition between potential problems is entailed by the carrying capacity of a public arena, which limits the number of social problems.

  followed by the Bouches-du-Rhône department in May 2009 and by the Isère, Ain and Rhône departments in June 2009. In 2013, only a ten-kilometer reach was affected by a complete fish-consumption interdiction in the Ain department, from Loyettes to Saint-Vulbas (the commune of Tredi where treats PCB waste). These interdictions were summarized by the association "Robin des Bois," which published the first edition of an atlas of PCB contaminated locations (Figure 3) in May 2008 and investigated different potential sources of pollutions (Robin des Bois, 2013). The three characteristics established by Downs in the introduction can easily be found in the 2005-2010 period: (a) less than twenty fishermen needed to find a new job, whereas the functions linked to leisure activities were saved, despite recreational anglers having to stop consuming their fish; (b) many jobs (in agriculture, dams, nuclear power plants, boating or tourism) depended on the Rhône but were not impacted by this environmental degradation, and local politicians used this event to launch political careers at a national scale; and (c) the health question does not benefit from thorough scientific research.

  2005 and reached a maximum in 2007. Content analysis showed that the pollution problem progressively propagated along the Rhône corridor with the availability of additional information: 18 percent was focused on specific sites, particularly the first contaminated site discovered (Grand Large and Canal of Jonage at the beginning of the study period, Le Progrès, 09/15/2005) and the site of an unofficial medical study and official research project in the Lower Rhône (Le Progrès, 03/05/2008).

Figure 6

 6 Figure6shows a factorial component analysis (FCA) performed on all of the words in the

  ): the State (70 occurrences), Prefects (64 occurrences), FRAPNA (59 occurrences), Tredi (the decontamination company was evoked 59 times), French food safety agency (AFSSA for Agence française de sécurité sanitaire des aliments), Ministry of Ecology (and its Minister Nathalie Kosciusko-Morizet) and EDF. Before 2007, the main stakeholders were the Prefects and FRAPNA. If EDF was central in 2005, it became an infrequently quoted stakeholder afterwards because it was found innocent. At the end of 2007, the role of the State became prominent and certain national institutions played a greater role, especially the AFSSA and Ministry of Ecology.

  might correspond to media coverage of PCB pollutions: (a) the pre-problem stage represents the beginning of media interest resulting from scientists and fishermen; (b) alarming discovery and euphoric enthusiasm are symbolized by the extension of the perimeter of consumption prohibitions that combine the confidence of players and seriousness of the problem; (c) cost of significant progress and consideration that the problem cannot prevent riverside inhabitants and users from engaging in the same activities as usual; (d) gradual decline of intense public interest out of boredom, worry and competition from new topical issues after 2008; and (e) post-problem stage when no solution is found and the media interest decreases. The temporal structure looks like a flood hydrograph, and steps A and B behave like a rising limb during a lag time before reaching a peak during step C. Steps D and E may correspond to a falling limb; however, this decline does not reveal the end of the problem, which may reappear through different forms at different times

  offers a systemic and synthetic vision of principles of selection in the studied newspapers. Different feedback was analyzed to understand two temporal dynamics: the problem-amplifying from 2005 to 2008 and the problem-damping.

  more information and they appeared to appreciate the fight carried by fishermen, environmental NGOs and scientists: "two scientists [A. Devaux and M. Babut, both quoted in four different articles] and an NGO evoke the limits of the first investigation. […] We shouldn't forget the other pollutions" (02/03/2009). From 2006 to 2007, many local and departmental stakeholders (professional and recreational fishermen, mayors, NGOs, etc.) decided to organize large demonstrations and to go to court to explanations for the diffusion of forbidden PCBs; this emphasized the media coverage. When the first research results

  1994-2006 period, and the first article was published on the 3 rd of March, 2007. At a regional scale, Le Dauphiné Libéré in the middle Rhône published its first article on the 4 th of March, 2007, and La Provence published their first article in the lower Rhône on the 21 st of April, 2007. The spatial diffusion of the prohibition from a specific site to the entire Rhône corridor, and finally to the national river network scale can also explain the media's growing interest towards PCBs. The spatial amplitude of phenomena in the Rhône catchment expanded with the discovery of many polluted river basins (including the Seine, Somme, Loire or Moselle Rivers). Because the situation appeared to be shared and serious, we noticed an amplifying problem; however, this propagation lasted two years. The same photographs (a panel with prohibition signs in Lyon, graphical abstract) have been used by different newspapers. The systematic differences in principles of selection may explain the two-year spreading of this issue as a social problem.

Figure 2 .

 2 Figure 2. The location of PCB pollutions of the Rhône River and the study media coverage.

Figure 3 .

 3 Figure 3. The PCB pollutions, associated actors and main management decisions: a) main

Figure 4 .

 4 Figure 4. Frequencies of nine main environmental issues considering the Rhône River in the

Figure 5 .

 5 Figure5. The number of published items related to PCB pollutions in a regional newspaper

Figure 6 .

 6 Figure 6. Position of years on the first factorial map of the correspondence analysis (F1 X F2)

Figure 7 .

 7 Figure 7. Synthetic view of newspaper content considering the PCB pollutions between 2005

Figure 8 .

 8 Figure 8. Cumulated frequency curves of the personally evoked stakeholders; their

Figure 9 .

 9 Figure9. Applying the conceptual model of the public arena[START_REF] Hilgartner | The Rise and Fall of Social Problems: A Public Arenas Model[END_REF],

Table 3 .

 3 The grid for the content analysis of texts.

Table 1 .

 1 An overview of analyses led by the institutional research.

	Main	Objectives of	Fish collection	Fish collection:	Levels of measured	Identified concerns and
	institutional	fish analyses	characterization:	where and	PCBs	consequences
	publications		species and	when?
			numbers
	DDASS, 2005 After an avian	2 breams	Canal of Jonage 7 iPCBs (congeners: 28,	Risk of chemical pollution : the
		botulism, a			52, 101, 118, 138, 153	fish-consumption interdiction in
		professional			and 180): 1365 and	the Canal of Jonage
		fisherman			1612 µg.kg -1 of wet	A need of scientific research on
		wanted to			weight (ww) for	iPCBs, but also on DL-PCBs and
		reassure his			∑iPCBs	PCDD/Fs.
		customers				The necessity of comparing
						different species.
	Afssa, 2006	More detailed	39 fish: 8	Three areas of	The average toxic	Interpretations linked with the
		analyses of	breams, 5	the Canal of	equivalent	European commission
		previous results,	barbels, 5 pikes,	Jonage	concentration (TEQ)	recommendation (n°199/2006):
		a study of the	11 catfish, 5		values [min.-max.]:	the sum of PCDD/F and DL-
		variability of	carps, 2 perches,		DL-PCBs: 14,09 pg.g -1	PCBs should be lower than 8
		fish	2pike-perches,		ww [1,5-71]	pg.g -1 ww for the toxic equivalent
		contamination	and 1 nase.		iPCBs: 220,41 [29-868]	concentration (TEQ) in all fish
		considering	Two categories		PCDD/Fs: 1,16 [0,08-	species, except eels (12 pg.g -1
		species and	are crated: 30		7,5]	ww). 23 fish have higher TEQ
		different parts	benthic species		∑iPCB are between 29	that 8 pg.g -1 . Only 4 fish have
		of the Rhône	and 9 pelagic		et 868 pg.g -1 and show a	higher TEQ of PCDD/Fs than 4
		River.	species.		correlation with with	pg.g -1 .
					the quantity of DL-	The useful decision of the Préfet
					PCBs.	to forbid the fish-consumption in
					Concerning the two	the Canal of Jonage: all fish seem
					categories, the benthic	to be contaminated.
					species have on average	The necessity to analyse other
					206 pg.g -1 of ∑iPCB	parts of the Rhône River and to
					[59-268], whereas the	understand the nature of
					other species have 87	pollutions.
					pg.g -1 [29-153]	A need of a better knowledge of
						sediment data contaminations, as
						the benthic species seem to be
						more contaminated.
	Afssa, 2007	To determine	260 fish: 21	Sites (Figure 2):	The average toxic	Interdictions in the Rhône, Isère,
		which results	Eels, 49 barbels,	P1 n=33	equivalent	Loire, Drôme, Ardèche,
		are in	29 breams, 16	(upstream Sault-	concentration (TEQ)	Vaucluse, Bouches-du-Rhône and
		compliance with	pikes, 21 carps,	Brénaz), P2	values [min.-max.]:	Gard departments
		European	24 chubs, 13	n=67 (Sault-	Eels: 20 pg.g -1 ww [1.2-	Eels (52%, in particular in P4
		regulatory	roaches, 16	Brénaz), P3	53.3]	area), barbels (63% often in P2
		thresholds,	nases, 6 mullet,	n=61	Barbels: 14.5 [2.4-46.7]	and P3 areas), breams (72%
		considering fish	12 perches, 14	(Confluence	Breams: 20.8 [0.6-18.5]	particularly in P2 and P3 areas),
		species.	pike-perches, 24	Saône-Rhône),	Pikes: 3.6 [0.2-21.2]	carps (67% in particular in P2 and
		To study if	catfish, 5 daces.	P4 n=79	Carps: 13.2 [1.4-49.9]	P3 areas), and catfish (75%, in
		some species	Different	(Confluence	Chubs:6.7 [0.2-48.7]	particular in P2 and P3 areas)
		may be	variables,	Isère-Rhône)	Roaches: 0.8 [0.2-1.7]	have more than 50% of their fish
		consumed,	including	and P5 n=20	Nases: 5 [0.2-13.6]	collection whose TEQ are higher
		according to	weight and size,	(Confluence	Mullet: 2 [0.2-6.6]	than European thresholds. It is a
		thresholds.	habitat and	Rhône-	Perches: 2.3 [0.1-12.1]	step to the emergence of partial
		To understand	habitat and	Durance).	Pike-perches: 2.1 [0.9-	interdictions: the prominence of
		potential	alimentation	From 2005 to	5.4]	species, habitats, fishing area, and
		transfer of PCBs	(prone to	2007	Catfish: 13.3 [1.3-59.3]	weight to understand PCB levels.
		from bottom	accumulate		Daces: 2.9 [1.8-5.4]	The Rhône River is polluted by
		sediment to fish.	PCBs, at the		The main observed non-	∑iPCB and DL-PCBs, but not by
			bottom and/or		conformities are linked	PCDD/Fs.
			feed on benthos		with DL-PCBs and not
			versus pelagic		with PCDD/F: for
			or diverse diet)		example eels 19 pg.g -1
					of DL-PCBs, barbels 14
					pg.g -1 of DL-PCBs,
					breams 18 pg.g -1 of DL-
					PCBs…

Table 2 .

 2 The (unknown) contemporary sources of PCB pollutions (after[START_REF] Pradelle | Évaluation des sources contributrices au flux de PCB du Rhône à la Méditerranée[END_REF] at the Arles station from 2008 to 2011. The sum corresponds to the seven indicator congeners (∑iPCB). Figure 1. Conceptual model of the public arena after

	Known or suspected sources of PCB	Estimation and trends of PCBI discharge in
	contaminations in the Rhône basin	the Rhône River and tributaries per year
	Atmospheric depositions	Between 6.1 and 8.2 kg
	Discharge of wastewater treatment plants	Between 0.4 and 4.3 kg
	Human excreta	Between 30 and 110 g
	Two PCB treatment facilities	0.4 kg
	Industrial waste	0.2 kg
	Unknown industrial waste	?
	Potential for leaching upon road and building	?
	disposal
	Landfills and polluted soils	?
	Accidents or vandalism	?
	Swiss discharges	?
	Total	From 21 to 153 kg from year to year
		-2008: 153 kg of PCBs
		-2009: 57 kg of PCBs
		-2010: 76 kg of PCBs
		-2011: 21 kg of PCBs

ACKNOWLEDGEMENTS

This research project was supported by the Zone Atelier Bassin du Rhône (ZABR) and Rhône Méditerranée and Corse Water Agency (Project: Mieux comprendre les discours de crise sur le fleuve Rhône: extrêmes hydrologiques et plantes invasives). It was conducted within the Observatoire Hommes-Milieux (OHM) Vallée du Rhône. We thank Silvia Flaminio and UMR 5600 EVS (ED2VS) for improving the quality of the English. We thank the editor and the three anonymous reviewers whose suggestions greatly improved the quality of the manuscript.

The weight can be an explanation: for example catfish less than 2 kg in P5 area cannot be considered as contaminated. [START_REF] Afssa | Avis de l'Agence française de sécurité sanitaire des aliments relatif à l'interprétation des résultats d'analyses du plan d'échantillonnage mis en place dans le cadre de la pollution en PCB des poissons du Rhône[END_REF] To analyse the species which exceed the European thresholds.

To 1930,1970,1980,1990,2000 Responsibilities 0 (no reference), Tredi (1), EDF (2), illegal waste

(3), blurred and ancient uses (4), unknown (