Orion Farr
email: orionfarr@gmail.com

Nil Gaudu

Gregoire Danger

Michael J Russell

Daniel Ferry

Wolfgang Nitschke

Simon Duval

Methanol on the rocks: Green rust transformation promotes the oxidation of methane

Shared coordination geometries between metal ions within reactive minerals and enzymatic metal cofactors hints at mechanistic and possibly evolutionary homology between particular abiotic chemical mineralogies and biological metabolism. The octahedral coordination of reactive Fe 2+/3+ minerals such as green rusts, endemic to anoxic sediments and the early Earth's oceans, mirrors the di-iron reaction center of soluble methane monooxygenase (sMMO), responsible for methane oxidation in methanotrophy. We show that methane oxidation occurs in tandem with the oxidation of green rust to lepidocrocite and magnetite, mimicking radical mediated methane oxidation found in sMMO to yield not only methanol but also halogenated hydrocarbons in the presence of seawater. This naturally occurring geochemical pathway for CH4 oxidation elucidates a previously unidentified carbon cycling mechanism in modern and ancient environments and reveals clues into mineral-mediated reactions in the synthesis of organic compounds necessary for the emergence of life.

II. Introduction:

Methane (CH4), although currently present at only 1.9 ppm, is the major heat-trapping greenhouse gas in terms of its radiative forcing effect, having 80x the effect of CO2 [1]. Anthropogenic emissions of CH4 now outweigh natural sources produced via biotic (organic degradation) and abiotic (serpentinization, mantle degassing) mechanisms. Natural sinks exist for CH4 but are insufficient to offset growing anthropogenic output. In the biosphere, CH4 is readily oxidized by methanotrophs, yielding methanol (MeOH), a key metabolic intermediate towards biomass formation [2,3]. In many species this metabolism employs the enzyme soluble methane monooxygenase (sMMO) to react CH4 with oxygen (O2), N2O, or H2O2 over an ephemeral di-Fe(IV) intermediate reaction center to achieve the conversion of CH4 to MeOH [4]. A similar reaction mechanism takes place within man-made catalysts where Fe(IV) reaction centers embedded within mineral scaffolds are used to convert CH4 to value-added products [5-7]. The oxidation state

Fe(IV), which is only ephemeral in nature, is crucial to the energetically demanding partial oxidation of CH4 for biological and industrial purposes [START_REF] Dummer | Methane Oxidation to Methanol[END_REF][START_REF] Banerjee | Structure of the key species in the enzymatic oxidation of methane to methanol[END_REF].

Methane is thought to have had an even larger role in climate regulation during the Hadean-Archean Eons 4.4 to 3.2 Ga, where the estimated atmospheric abundance of greenhouse gasses like CH4, CO2, and N2O were orders of magnitude greater than modern, supplying ample CH4 for the proliferation of primitive methanotrophs [START_REF] Arney | The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth[END_REF][START_REF] Catling | The Archean atmosphere[END_REF]. This anerobic metabolism, along with various others, dominated the biosphere until the emergence of oxygenic photosynthesis during the great oxidation event (GOE) [START_REF] Schirrmeister | Cyanobacteria and the Great Oxidation Event: Evidence from genes and fossils[END_REF].

Of pertinence to the experiments and outcomes reported herein, the octahedral di-iron reaction center structure of sMMO shares similar coordination geometry to the octahedral di-valent iron lattice coordination in green rusts (GR) (Figure 1) [START_REF] Duval | Fougerite: The not so simple progenitor of the first cells[END_REF]. This group of naturally forming, metastable, reactive, layered double hydroxide (LDH) minerals are known for their redox capabilities in carrying out the reduction of metals (e.g., Cu, As, U), inorganic compounds (e.g., NO3 -, ClO4 -), and organic compounds (e.g., CT, TCE, TCM [START_REF] Jönsson | Sorption of As(III) and As(V) to siderite, green rust (fougerite) and magnetite: Implications for arsenic release in anoxic groundwaters[END_REF][START_REF] Døssing | Reduction of hexavalent chromium by ferrous iron: A process of chromium isotope fractionation and its relevance to natural environments[END_REF][START_REF] Choi | Nitrate reduction by green rusts modified with trace metals[END_REF][START_REF] Etique | Nitrate reduction by mixed iron(II-III) hydroxycarbonate green rust in the presence of phosphate anions: The key parameters influencing the ammonium selectivity[END_REF][START_REF] Onoguchi | Kinetics and mechanism of selenate and selenite removal in solution by green rust-sulfate[END_REF][START_REF] Buessecker | Mineral-catalysed formation of marine NO and N2O on the anoxic early Earth[END_REF]. GR's unique structure consists of a charged octahedrally coordinated bilayer of divalent Fe 2+/3+ cations which can integrate other transition metals (e.g., Ni, Co, Zn, Mg, Al) and sandwich interchangeable anions (e.g., CO3 2-, HCOO -, Cl -, SO4 2-) [START_REF] Usman | Magnetite and Green Rust: Synthesis, Properties, and Environmental Applications of Mixed-Valent Iron Minerals[END_REF]. The mineral reacts with oxygen, radicals, and temperature to undergo pH-and redox-dependent transformations into other reactive minerals, namely magnetite and lepidocrocite, playing a yet unquantified role in the geochemical cycling of sub-oxic subsurface environments [START_REF] Trolard | Chapter 5 Geochemistry of Green Rusts and Fougerite[END_REF][START_REF] Zegeye | Green rust formation controls nutrient availability in a ferruginous water column[END_REF][START_REF] Farr | Effect of Ni2+, Zn2+, and Co2+ on green rust transformation to magnetite[END_REF]. Of note is its proposed role in marine nutrient and metal geochemical cycling prior to the GOE at ~ 2.5Ga [START_REF] Dodd | Abiotic anoxic iron oxidation, formation of Archean banded iron formations, and the oxidation of early Earth[END_REF][START_REF] Halevy | A key role for green rust in the Precambrian oceans and the genesis of iron formations[END_REF], and its hypothesized suitability as an "abiotic enzyme" linking geochemical proto-metabolism with the evolution of enzymatic biochemistry prior to the emergence of life [START_REF] Duval | Fougerite: The not so simple progenitor of the first cells[END_REF][START_REF] Russell | Green Rust: The Simple Organizing[END_REF][START_REF] Russell | A self-sustaining serpentinization mega-engine feeds the fougerite nanoengines implicated in the emergence of guided metabolism[END_REF][START_REF] Barge | Redox and pH gradients drive amino acid synthesis in iron oxyhydroxide mineral systems[END_REF]. The di-iron structure present in sMMO and synthetic catalysts is known to be the key site essential in the oxidation of methane. Thus, the presence of an analogous structure in GR suggests that it also has the potential to catalyze methane oxidation. In this study, we experimentally demonstrate the viability of this proposed analogous catalytic behavior by reacting green rust with CH4 and O2 to produce significant quantities of MeOH and halogenated organics. These results uncover previously unrecognized redox reactions with GR and the carbon cycle, yielding significant environmental implications to the modern and ancient Earth.

III.

Methods:

1.1 Mineral synthesis Three GR species and their transformation products were synthesized following a procedure based on GRCO3 syntheses outlined in [START_REF] Ruby | Coprecipitation of Fe(II) and Fe(III) cations in sulphated aqueous medium and formation of hydroxysulphate green rust[END_REF] and [START_REF] Bocher | Coprecipitation of Fe(II-III) hydroxycarbonate green rust stabilised by phosphate adsorption[END_REF]. The main species of GR studied was a green rust intercalated with the carbonate anion (GRCO3) and its synthesis is described below. Synthesis for GRSO4 and GRCl is detailed in the supplementary section S1.

A concentrated stock solution of simulated seawater (80 ml) containing 150 mM FeCl2⸳⸱H2O, 50 mM FeCl3, 50 mM of MgCl, and 400 mM of NaCl was prepared using deoxygenated ultra-purified water (milli-Q) and purged with N2 gas for 30 minutes in a sealed 125 mL reactor vial. A solution (20 ml) of 300 mM NaOH and 30 mM Na2CO3 was then injected into the reactor via a N2-purged needle syringe and the mixture was gently shaken. A dark green precipitate formed which was then confirmed to be GRCO3 via powder X-ray diffraction (section d), which was stable indefinitely. The total Fe concentration in this stock solution was 200 mM and final pH was ~7.

Methane oxidation reactions

The pressurized reactions took place inside a 200 ml Parr autoclave reactor pressurized to 0, 1, 10, 30, 50 bar CH4 (Linde Gas 99.99%), 0-3 bar O2 (Linde), 1 bar NO (Linde Gas 5%), at 25°C. Within the reactor 20-100 ml glass vials with stirrers, butyl or screw top caps, and needle-perforated septa were used to contain the replicate mineral suspensions. These vials were then removed and stored under anoxic conditions before their headspaces were analyzed using GC-MS.

Headspace Analysis

GC gas chromatography coupled to an ISQ mass spectrometer (ThermoFisher Scientific). The sampling was performed by headspace (HS) using an RSH auto-sampler (ThermoFisher Scientific). 5 mL of each sample was deposited on a 20 mL HS vial with screwtop PTFE septas. Each vial was then incubated during 6 min at 55°C under agitation. The HS sampling was performed by collecting 2 mL of the gas phase. It was then injected into the GC via an injector at 250°C, a split at 10 mL/min and a column flow of 1.1 mL/min. The column was a Stabilwax-DA from Restek (length 30m, diameter 0.25 mm, film thickness 0.5µm). Analyses were performed with the temperature gradient that starts with a 1 min isotherm at 35°C and proceeds with a gradient at 25°C/min up to 220°C ending with a 2 min isotherm. The detection was performed with the MS in full scan or SIM mode using an electron impact ionization at 70eV. MS transfer line and ion source temperatures were set at 250°C. For the full scan analyses, the m/z range was 20-300 au, meanwhile for the SIM m/z 31 and 84 were isolated for MeOH and TCM identification (Figure S6).

Mineral characterization

Mineral transformation over the course of the reaction was monitored using X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Samples were centrifuged, decanted, and dried under a stream of N2 gas. For XRD analysis glycerol was added prior to analysis to prevent oxidation and the paste was transferred into a glass ampule for XRD analysis in a

Rigaku RU 200BH diffractometer with Cu anode (λ = 1.5418Å), scanning from 2 theta values of 2-80 degrees. For TEM analysis, an aliquot of dried mineral was deposited on a copper grid coated with a holey carbon film (AGAR Scientific, S147-3). Grids were then transferred to a Jeol-JEM2010 electron microscope operated at 200 kV and GR particles were observed in bright field mode. For SEM analysis, an aliquot of dried mineral was deposited on an aluminum sample holder and then transferred to a Jeol JSM-7900F electron microscope and analyzed using accelerating voltages ranging from 5 to 15 kV.

IV. Results:

The pressurization of GR with CH4 and O2 resulted in the production of MeOH along with various other compounds, including trichloromethane (TCM) and dichloromethane (DCM). Various conditions were tested to optimize the yield of MeOH. Multiple concentrations were examined and the relationship between [MeOH]/[Fe] is compared (Supplementary figure 5). MeOH is only detected with GR in the initial solution, as solutions containing FeCl2, FeCl3, or H2O did not produce detectable levels of MeOH under the same conditions. No MeOH is detected without the added oxidants. Substitutes for O2, NO and H2O2, were tested and found to produce products of CH4 oxidation (Supplementary figure 7). Coinciding with MeOH production was the production of various organic compounds produced in µM quantities. The most prevalent compounds detected other than MeOH were halogenated organics, mainly TCM and DCM (Supplementary figure 2). The concentration of TCM and DCM increased in response to increased pressure, however DCM was the primary organohalogen detected at higher pressures (30 bar) versus TCM dominating at lower pressures. Trace amounts of TCM were also detected without the presence of O2 in aged GRCO3 solutions exposed to CH4. However, TCM was also produced in solutions of FeCl2 when exposed to CH4. Other organic products were produced but were not easily replicated and thus were not quantified: these compounds included C1-C12 hydrocarbons, butanal, pentanal, paraformaldehyde, acetaldehyde, and dimethyl ether. GR undergoes transformation to two mineral phases following the exposure to pressurized CH4 and O2 mixtures, oxidizing to either magnetite (Fe3O4) or lepidocrocite (-FeO(OH)) according to XRD (Figure 3a). The presence of O2 (0-1 bar) at the start of the reaction resulted in different transformation product yields, with increased O2 selecting for  -FeO(OH) over Fe3O4. In the case of transformation to Fe3O4, d spacing for the low 2θ peak shifts from 7.6 A to 7.9 A. Full transformation takes place within 68 hours of reaction. SEM (Figure 3b) images show distinct transformation from GR's characteristic 10 to 500 nM hexagonal platelets, through an intermediate phase with hexagonal plates studded with <100 nM spheroid assemblages or <100nm irregular acicular crystals, to a fully transformed phase with only spheroids or acicular crystals. The transformation of GR results in a decrease from an initial average pH of 7 to 5.

v. Discussion:

Our experiments show that the oxidative transformation of GR in the presence of CH4 results in the oxidation of CH4, to a variety of products. In section a, we discuss the analysis of MeOH, as well as the other compounds (e.g. TCM, DCM) detected in significant quantities.

a. The concurrent oxidation of green rust and methane

The production of MeOH at various pressures and over time is depicted in figure 2, showing significant quantities are produced in solutions of GR pressurized to 1-50 bar over 60 hours, given the initial presence of 0.2 bar of O2 at the start of the experiment. However, in the absence of oxygen, the introduction of CH4 to GR resulted in little to no MeOH production. Substitutes for O2 were tested, using H2O2 (Supplementary figure 5) and NO (Supplementary figure 7) in separate experiments, yielding MeOH and butanal respectively. The presence of a sufficient oxidant is therefore implicated in the successful oxidation of methane using GR.

Increasing CH4 pressure resulted in a linear increase in MeOH concentration over a range of [Fe] (200, 100, 30 mM). Increasing the concentration of Fe results in higher yield of MeOH, however the efficiency of the production of MeOH/Fe falls dramatically (Supplementary figure 5). GR's affinity to hydrophilic O2 and as well as radical scavenging likely dominates surface interactions versus hydrophobic gases like CH4. The reaction rate is thus dependent on how much CH4 is in contact with the mineral surface, which is controlled by the concentration of dissolved CH4 in solution (Figure 2). CH4 solubility is controlled by pressure and chloride concentration due to CH4's low solubility in distilled water at STP (25 C:1 bar)solubility increases 42% from 1 to 50 bars but is decreased by 20% with the addition of 0.4 M Cl - [START_REF] Duan | The prediction of methane solubility in natural waters to high ionic strength from 0 to 250°C and from 0 to 1600 bar[END_REF]. The solubilization of CH4 is one route for aqueous mineral reactions, however within pore spaces common to sediments and hydrothermal systems where this reaction would occur, direct contact with trapped CH4 bubbles would offer a more direct mineral-to-gas interface, increasing the reaction rate.

The substitution of interlayer anions is known to affect GR reactivity [START_REF] Agnel | Mechanistic and Thermodynamic Insights into Anion Exchange by Green Rust[END_REF] and our investigation of Cl -, CO3

, and SO4 2-(Supplementary figure 4) shows an unexpected trend in reactivity with CO3 2->Cl ->SO4 2-. With prior work in GR, redox reactions involving the various anions show clear preference for Cl -and SO4 2- over CO3 2-reactions [START_REF] Usman | Magnetite and Green Rust: Synthesis, Properties, and Environmental Applications of Mixed-Valent Iron Minerals[END_REF]. A shift in d-spacing (Figure 3) from 7.6A to 7.9A corresponds to a shift in interlayer anion species from CO3 2-to Cl -during transformation from GR to Fe3O4 [START_REF] Usman | Magnetite and Green Rust: Synthesis, Properties, and Environmental Applications of Mixed-Valent Iron Minerals[END_REF]. As the GRCO3 and GRCl solutions were conducted in simulated seawater, a mixed or transitory interlayer phase of CO3 2-+Cl - could conceivably be responsible for increased reactivity towards CH4 oxidation. The increased MeOH production could also be linked to the reduction of interlayer bound CO3 2-during the reaction [START_REF] Lee | In press. Spontaneous Unassisted Conversion of CO 2 to Multicarbon Liquid Products on Green Rust Mineral[END_REF].

The production of halogenated organic molecules was observed (Supplementary figure 2): GR appears to catalyze CH4 chlorination as TCM and DCM are products in solutions containing GR and NaCl. GR and magnetite are known to reduce halogenated organics [START_REF] Erbs | Reductive dechlorination of carbon tetrachloride using iron(II) iron(III) hydroxide sulfate (green rust)[END_REF], which may explain the preference for DCM over TCM at higher pressure. Given time, this reduction should continue to methyl chloride and CH4.

Chlorine could likely be replaced by other environmentally relevant halogens such as iodine or bromine, indicating a general abiotic link between Fe redox and halogen cycling in the environment.

MeOH was not detected in parallel experiments using solutions of H2O, NaCl, or FeCl2, or FeCl3 in place of GR. Since no MeOH is formed without GR or without O2, GR must be producing a short-lived reactant during oxidation necessary for the reaction to proceed over GR or its oxide transformation products; ferric green rust, magnetite, or lepidocrocite.

b. Radicals and Fe(IV) mediated oxidation mechanism

The presence of radicals and Fe(IV) oxidation states are routinely implicated in CH4 oxidation research as a main mechanism for achieving the energetically difficult partial oxidation of methane over transition metal bearing mineral catalysts such as zeolites [START_REF] Starokon | Oxidation of methane to methanol on the surface of FeZSM-5 zeolite[END_REF][START_REF] Dummer | Methane Oxidation to Methanol[END_REF]. These high surface area aluminosilicate minerals bear Fe (II-III) reaction sites which readily react with oxidative species such as O2, H2O2, N2O, UV, or radicals to create short lived reactive Fe(IV) oxidation states which can effectively conduct CH4 oxidation [START_REF] Nizova | Catalytic oxidation of methane to methyl hydroperoxide and other oxygenates under mild conditions[END_REF][START_REF] Dummer | Methane Oxidation to Methanol[END_REF][START_REF] Szécsényi | Mechanistic Complexity of Methane Oxidation with H2O2 by Single-Site Fe/ZSM-5 Catalyst[END_REF]. This Fe(IV) state is likewise responsible for CH4 oxidation in microbial methanotrophy, where the enzyme sMMO uses oxidant-activated Fe(IV) reaction centers to transform CH4 to MeOH [START_REF] Kopp | Soluble methane monooxygenase: activation of dioxygen and methane[END_REF].

Correspondingly, in GR, it's oxidative transformation is known to produce a significant amount of hydroxyl radicals, H2O2, and Fe(IV) sites [START_REF] Fang | Induced generation of hydroxyl radicals from green rust under oxic conditions by iron-phosphate complexes[END_REF][START_REF] Li | Green rust (GR) and glucose oxidase (GOX) based Fenton-like reaction: Capacity of sustainable release, promoted conversion of glucose through GOX-iron and pH self-adjustment[END_REF] which have been observed to promote the degradation of complex organic molecules [START_REF] Hanna | Fenton-like oxidation and mineralization of phenol using synthetic Fe(II)-Fe(III) green rusts[END_REF][START_REF] Matta | Oxidation of phenol by green rust and hydrogen peroxide at neutral pH[END_REF].

Given the known relationship between radical production, Fe(IV) sites, and methane oxidation, we propose that GR mediates CH4 oxidation via radical mediated oxidation pathway over short-lived Fe(IV) sites in a manner similar to sMMO [START_REF] Banerjee | Structure of the key species in the enzymatic oxidation of methane to methanol[END_REF] or Fe-ZSM zeolites [START_REF] Starokon | Oxidation of methane to methanol on the surface of FeZSM-5 zeolite[END_REF] To further test this hypothesis, we replicated the experimental conditions for GRCO3 at 1 bar CH4 and replaced O2 with 1 mM of H2O2 which yielded a significant amount of MeOH even without high pressures (Supplementary figure 5). This indicates the reaction is dependent on the interaction between hydroxyl radicals, iron, and CH4 [START_REF] Anipsitakis | Radical Generation by the Interaction of Transition Metals with Common Oxidants[END_REF]. Furthermore, MeOH serves as a radical scavenger resulting in its own oxidation to formaldehyde (which was detected), formate, and CO2 [START_REF] Alshehri | Methanol oxidation on transition elements oxides[END_REF]. The production of organohalogens in the presence of Cl -anions, likely through a radical chlorination pathway [41], adds further evidence to the radical-based hypothesis. In this case, the Cl -radical ion substitutes for the hydroxyl radical to oxidize CH4 yielding methyl chloride (MC), DCM, and TCM, instead of MeOH, which was observed in our experiments.

c. Implications

The discovery of a naturally occurring mineral-based mechanism for CH4 oxidation is novel and hints at large scale geochemical processes that have been overlooked with past research.

Feasibility and environmental relevance

The conditions simulated within the pressure reactor (GR in contact with pressurized CH4) provided optimal conditions for the reaction in addition to serving as an analogue to environmental conditions where GR could conceivably interact with sources of CH4 at depth. GR has been isolated in deep anoxic ferruginous lakes [START_REF] Zegeye | Green rust formation controls nutrient availability in a ferruginous water column[END_REF] and is speculated to form at hydrothermal vents and [START_REF] Trolard | Mineralogy, geochemistry and occurrences of fougerite in a modern hydrothermal system and its implications for the origin of life[END_REF] where oxygen-poor hydrothermal fluids meet cold oxygen-rich sea water. In both locales, abiotic and biotic sources of CH4, pressurized at depths (e.g. 100 m depth = 10 bar pressure) would fall within the range of conditions we tested. For environments closer to STP, such as wetland sediments, soils, and ground water, our experimental results still demonstrate GR's reactivity towards CH4 oxidation, albeit one accelerated by pressure. We observed both MeOH and halogenated organics at 1 bar CH4, though in low concentrations, indicating that mineral based CH4 oxidation will take place even under STP. The discovery of naturally occurring mineral-based mechanism for CH4 oxidation is novel and hints at global geochemical processes that have been previously overlooked.

Implied role of green rust in carbon and halogen cycling in modern environments

Green rusts are well studied for their use in the degradation of organohalogen pollutants in the environment [START_REF] Maithreepala | Enhanced dechlorination of chlorinated methanes and ethenes by chloride green rust in the presence of copper(II)[END_REF][START_REF] Choi | Enhanced degradation of tetrachloroethylene by green rusts with platinum[END_REF][START_REF] O'loughlin | Reduction of Chlorinated Ethenes by Agand Cu-Amended Green Rust[END_REF][START_REF] Yao | Synthesis, characterization and performances of green rusts for water decontamination: A review[END_REF], however they have never been linked to organohalogen formation via CH4 oxidation. Recent observations revealed that salt plains, rainforests, and soils are the source of abiotic emissions of chloromethanes [START_REF] Huber | Natural abiotic formation of trihalomethanes in soil: Results from laboratory studies and field samples[END_REF][START_REF] Redeker | Methyl chloride isotopic signatures from Irish forest soils and a comparison between abiotic and biogenic methyl halide soil fluxes[END_REF][START_REF] Wittmer | Iron(III)-induced activation of chloride from artificial sea-salt aerosol[END_REF][START_REF] Bahlmann | Evidence for a major missing source in the global chloromethane budget from stable carbon isotopes[END_REF][START_REF] Sattler | Natural formation of chloro-and bromoacetone in salt lakes of Western Australia[END_REF]. Of note is the isotopic fractionation of some of these signatures, implying an abiotic source [START_REF] Bahlmann | Evidence for a major missing source in the global chloromethane budget from stable carbon isotopes[END_REF]. As mentioned previously, GR is common in these types of waterlogged environments [START_REF] Trolard | Identification of a green rust mineral in a reductomorphic soil by Mossbauer and Raman spectroscopies[END_REF] and within anoxic regions of stratified bodies of water and rivers with high iron content [START_REF] Zegeye | Green rust formation controls nutrient availability in a ferruginous water column[END_REF][START_REF] Jorand | The formation of green rust induced by tropical river biofilm components[END_REF]. In soils, Fe is already known to halogenate decaying organic matter [START_REF] Huber | Natural abiotic formation of trihalomethanes in soil: Results from laboratory studies and field samples[END_REF], the direct oxidation of CH4 has not yet been observed in the environment. Our experiments show that it is feasible for GR to be oxidatively transformed to reactive Fe-oxides in the presence of CH4, thus catalyzing abiotic CH4 oxidation and chloromethane production. As CH4, halomethane, and halogen flux greatly affect climate forcing [START_REF] Li | Reactive halogens increase the global methane lifetime and radiative forcing in the 21st century[END_REF] uncovering the role reactive minerals play in these cycles may help constrain their input over climate change. Overall, the further study of these environments should take care to identify O2-sensitive minerals like GR, to understand the extent of their influence over the geochemical cycling of carbon and halogens.

Methane oxidation on the ancient Earth

Abiotic CH4 oxidation may have played a greater role in the deep past as long periods of ferruginous oceans characterized the Archean (4-3.5 Ga) and Proterozoic (3.5-2 Ga) eons [START_REF] Halevy | A key role for green rust in the Precambrian oceans and the genesis of iron formations[END_REF][START_REF] Poulton | Ferruginous conditions: A dominant feature of the ocean through Earth's history[END_REF][START_REF] Thibon | Dynamics of oceanic iron prior to the Great Oxygenation Event[END_REF]. During these periods GRs are thought to have been abundant and likely shepherded marine geochemistry at the interface between land, air, and sea [START_REF] Zegeye | Green rust formation controls nutrient availability in a ferruginous water column[END_REF][START_REF] Halevy | A key role for green rust in the Precambrian oceans and the genesis of iron formations[END_REF][START_REF] Koeksoy | Formation of green rust and elemental sulfur in an analogue for oxygenated ferroeuxinic transition zones of Precambrian oceans[END_REF]. Prior to the GOE and the subsequent proliferation of O2 in marine environments; geochemically generated radical species [START_REF] Anipsitakis | Radical Generation by the Interaction of Transition Metals with Common Oxidants[END_REF][START_REF] He | An abiotic source of Archean hydrogen peroxide and oxygen that pre-dates oxygenic photosynthesis[END_REF][START_REF] Zhao | Redox Oscillations Activate Thermodynamically Stable Iron Minerals for Enhanced Reactive Oxygen Species Production[END_REF][START_REF] He | A mineral-based origin of Earth's initial hydrogen peroxide and molecular oxygen[END_REF][START_REF] Ernst | Methane formation driven by light and heat prior to the origin of life and beyond[END_REF], thermochemical processes [START_REF] Farr | Effect of Ni2+, Zn2+, and Co2+ on green rust transformation to magnetite[END_REF][START_REF] Huang | Thermochemical oxidation of methane by manganese oxides in hydrothermal sediments[END_REF], natural electrochemical processes [START_REF] Nitschke | Aqueous electrochemistry: The toolbox for life's emergence from redox disequilibria[END_REF][START_REF] Ooka | Electrochemistry at Deep-Sea Hydrothermal Vents: Utilization of the Thermodynamic Driving Force towards the Autotrophic Origin of Life[END_REF][START_REF] Lee | Spontaneous Unassisted Conversion of CO 2 to Multicarbon (≥ C 2 ) Liquid Products on Green Rust Mineral[END_REF], photochemistry [START_REF] Dodd | Abiotic anoxic iron oxidation, formation of Archean banded iron formations, and the oxidation of early Earth[END_REF][START_REF] Ernst | Methane formation driven by light and heat prior to the origin of life and beyond[END_REF], nitrogen oxides [START_REF] Buessecker | Mineral-catalysed formation of marine NO and N2O on the anoxic early Earth[END_REF][START_REF] Wong | Nitrogen Oxides in Early Earth's Atmosphere as Electron Acceptors for Life's Emergence[END_REF], and nitrogen oxyanions [START_REF] Ducluzeau | Was nitric oxide the first deep electron sink?[END_REF][START_REF] Barge | Prebiotic reactions in a Mars analog iron mineral system: Effects of nitrate, nitrite, and ammonia on amino acid formation[END_REF], may have served as potential surrogates for the oxidation of GR and thus CH4, creating a CH4 sink within the ancient Archean ocean. As O2 concentrations increased following the GOE, the oxidation of GR-bearing oceans may have played a role in the drawdown of atmospheric CH4 concentrations [START_REF] Catling | The Archean atmosphere[END_REF], impacting climate throughout the Proterozoic [START_REF] Guilbaud | A global transition to ferruginous conditions in the early Neoproterozoic oceans[END_REF][START_REF] Jaziri | Dynamics of the Great Oxidation Event from a 3D photochemical-climate model[END_REF].

As halomethanes exert strong influences over the greenhouse effect [START_REF] Li | Reactive halogens increase the global methane lifetime and radiative forcing in the 21st century[END_REF], the effect of their production by a GR saturated ocean on the Archean climate is currently unstudied. As such, the detection of exoplanet halomethane signatures may not necessarily indicate the presence of life, as was recently suggested [START_REF] Leung | Alternative Methylated Biosignatures. I. Methyl Bromide, a Capstone Biosignature[END_REF]. However, as life is thought to have emerged sometime in the late Hadean to early-Archean, the oxidation of abundant CH4 [START_REF] Catling | The Archean atmosphere[END_REF] to more biochemically accessible compounds such as MeOH, hydrocarbons, and halogenated organics may have played important roles both before and after its emergence.

More specifically, our results strengthen an emergence-of-life hypothesis that invokes a pathway for GRmediated protocell synthesis [START_REF] Russell | Methane: Fuel or Exhaust at the Emergence of Life?[END_REF][START_REF] Duval | Fougerite: The not so simple progenitor of the first cells[END_REF][START_REF] Russell | Green Rust: The Simple Organizing[END_REF][START_REF] Russell | A self-sustaining serpentinization mega-engine feeds the fougerite nanoengines implicated in the emergence of guided metabolism[END_REF], where hydrothermal CH4 is oxidized to multi-carbon compounds within GR-saturated mineral membranes precipitated at the redox boundary between reducing alkaline vent effluent and oxidizing acidic ocean waterthe type of disequilibria considered to have driven life into being [START_REF] Russell | The inevitable journey to being[END_REF]. Just as in the biological metabolism of methanotrophy, methane would thereby serve both as a feedstock for production of organics and as a source of a cascade of increasingly reducing electrons derived from the further oxidation of MeOH, formaldehyde etc, as discussed in [START_REF] Russell | Methane: Fuel or Exhaust at the Emergence of Life?[END_REF][START_REF] Nitschke | Aqueous electrochemistry: The toolbox for life's emergence from redox disequilibria[END_REF].

As pointed out previously, such entropy-decreasing processes are prerequisites for thermodynamically meaningful emergence-of-life scenarios [START_REF] Branscomb | Frankenstein or a Submarine Alkaline Vent: Who is Responsible for Abiogenesis?: Part 2: As life is now, so it must have been in the beginning[END_REF]. Given the similarities between sMMO's di-iron reaction center and GR's atomic lattice coordination, a proposed evolutionary link between minerals and enzymes is suggested [START_REF] Nitschke | On the antiquity of metalloenzymes and their substrates in bioenergetics[END_REF]. Because GR has a uniquely versatile structure which allows for chemical exchange;

integrating several essential metals (e.g., Co, Ni, Zn, Mo) and anionic (e.g., NO 3-, formate, linear carbon chain) species, it is suggested that its reactive surfaces and bilaterally active interlayers served as sites for organic synthesis and concentration [START_REF] Helmbrecht | White and green rust chimneys accumulate RNA in a ferruginous chemical garden[END_REF] at early submarine alkaline hydrothermal vents, and that these interlayers also compartmentalized and guided the free-energy converting proto-metabolic processes which led to the emergence of life [START_REF] Duval | Fougerite: The not so simple progenitor of the first cells[END_REF][START_REF] Russell | Green Rust: The Simple Organizing[END_REF][START_REF] Russell | A self-sustaining serpentinization mega-engine feeds the fougerite nanoengines implicated in the emergence of guided metabolism[END_REF].

vi. Conclusion:

We demonstrate that the oxidative transformation of green rust in the presence of methane yields methanol, along with organohalogens and various other organic compounds. This newly discovered behavior implies the existence of previously undetected links between iron, carbon, and halogen redox cycling in modern and ancient environments mediated by reactive minerals. Furthermore, the oxidation of CH4 mediated by an abiotic GR mineral invites further research into the relationship between the evolution of primitive microbial metabolisms and the abiotic geochemical processes that preceded them.

vii.

Figure 1 .

 1 Figure 1. A diagram comparing the structural similarities between GR and sMMO. From left to right, an illustration of a single GR crystal, the crystal's cation and anion LDH structure, the octahedral coordination of iron (yellow) and oxygen (red) atoms in GR, the analogous atomic structure of the MMO reaction center (nitrogen = blue), and a model of the enzyme MMO.

Figure 2 :

 2 Figure 2: Effect of pressure and time on methanol concentration. (a) displays methanol concentrations at given CH4 partial pressure following 24 hours of reaction time in solutions containing GRCO3, FeCl2, FeCl3, and H2O. (b) displays a related set of experiments conducted at [Fe] = 30 mM, showing methanol production over time.

Figure

  Figure 2b shows the production of MeOH over time in solutions of GRCO3 ([Fe]=30mM) with partial pressures of CH4 from 0 to 30 bar mixed with 0.2 bar O2. These experiments were conducted at lower concentrations of Fe than Figure 2 (30 vs 200mM). No MeOH is detected in solutions of GR not exposed to CH4. With 1 bar CH4 there is a mild increase to ~5µM of MeOH. At 10 bars CH4 there is an increase from 0 to ~40µM of MeOH by 80 hours. At 30 bar of CH4 we show an increase from 0 to ~55µM of MeOH by 68 hours of reaction time. The addition of 0.2 bar O2 and subsequent MeOH production resulted in changes to solution pH, which was recorded to drop from an initial value of 7 to 6 by 24 hours and 5 by ~70 hours. Additional experiments were attempted with 1 bar O2 and 10 bar CH4, leading to rapid mineral transformation yet no measurable MeOH production.

Figure 3 -

 3 Figure 3 -Section A displays the XRD diffractograms of the mineral species produced following the exposure of GRCO3 to pressurized CH4/O2 atmospheres. Magnetite (Fe3O4) and lepidocrocite (-FeO(OH)) were the primary transformation products of GR corresponding to low (~0.1 bar) and high (>0.1 bar) O2 content respectively. Partially transformed products are displayed below the primary product, with the residual GR's low 2 d-spacing listed adjacent. Section B displays the corresponding SEM images of the pure mineral phases characterized in section A.

Acknowledgements: This work received support from the French Government under the France 2030 investment plan, as part of the initiative d'Excellence d'Aix Marseille Université (A*MIDEX -AMX-21-PEP-039) as well as a grant from the French Agence Nationale pour la Recherche (ANR-22-CE30-0035-01). We thank Vasile Heresanu for performing XRD measurements, Alexandre Altié and Damien Chaudanson for SEM/TEM support, Frederic Brunel for lending us the pressure reactor, and Olivier Grauby for helpful discussions on green rust.

viii.

Authors contributions

OF designed and performed experiments. OF, NG, GD, MR, DF, WN, SD contributed to the manuscript.

Conflict of interest

The authors note no conflict of interest.

x.


Fabienne Wateau

Regina Carmem

Daniela Giongo

Johnny Figueiredo

Manuelle Reis

Lago

UNWANTED LEGACY AND MEMORY OF THE MILIEU: TOXIC MATERIALS, REMEDIATION, HABITUATION (ESTARREJA, PORTUGAL)

Introduction -Damaged World

Between Land and Water, the Place is Magnificent

On the Portuguese Atlantic coast, south of Porto, a large lagoon of brackish water has been designated as a Special Protection Area (SPA) by the Natura 2000 network (Natura 2000). It offers a rich habitat favourable to the reproduction of a large number of migratory birds; the landscape has become very popular for birdwatchers and tourists because of the layout of its promontories, pastoral paths, and cyclable bridges. Between land and water, the place is magnificent. Nature is as if preserved there, some of it wild, totally unspoiled by contamination.

And it is this particularly positive image that local politicians and institutions go to great lengths to defend and protect. On the periphery of Estarreja city, which has been home to an industrial chemical facility since the 1950s and also has its feet in the water of this lagoon, one area in particular -which is called BioRia today, and was once a spillway for toxic products from the facility's factories -won the 2008 prize for best environmental rehabilitation and biodiversity preservation on the Ria de Aveiro. BioRia is the new calling card brandished by the city council, in association with PACOPAR, a multi-actor consortium organised around the factories, which itself also won a prize from the 2005 European Responsible Care Awards. 1 It is therefore between Aveiro and Estarreja that this study is geographically situated; and it is between toxic materials, remediation and habituation that it takes its sociological context. 2 In response to this book's theoretical argument, which encourages us to question the idea of toxicity as heritage, the article will begin by reviewing some of the anthropological literature on recovery, then consider the proposed concept of toxic heritage, and finally, present the chosen case study in connection with memory and heritage.

Among Optimism and Utopia

Rehabilitating, restoring, and remedying. Because we didn't manage to prevent, contain, or protect. Rachel Carson's book Silent Spring certainly attempted to alert populations and decision-makers when she asserted that 'along with the possibility of the extinction of mankind by nuclear war, the central problem of our age has therefore become the contamination of man's total environment with such substances of incredible potential for harm -substances that accumulate […]'. (Carson 2002, 7). In addition to this 'obligation to endure', it seems that we have subsequently been imposed the obligation of 'staying with the trouble'. Donna [START_REF] Haraway | Staying with the Trouble. Making Kin in Chthulucene[END_REF], Ana [START_REF] Tsing | The Mushroom at the End of the World: On the Possibility of Life in Capitalist Ruins[END_REF] and [START_REF] Latour | Où Atterrir? Comment s'orienter en politique[END_REF][START_REF] Bruno | Où suis-je? Leçons du confinement à l'usage des terrestres[END_REF] -to name a few -are part of this optimistic, benevolent trend of raising awareness about a better world, advocating possible forms of earth resurgence (Terra/Gaïa): 'The task is to become capable, with each other […], of response. Staying with the trouble does not require such a relationship to times called the future. Staying with the trouble requires learning to be truly present, not as a vanishing pivot between awful or edenic pasts and apocalyptic or salvific futures […]'. She sets out another model, of 'oddkin […] unexpected collaborations and combinations […] We become-with each other or not at all […] Sympoiesis-making-with' is the way to go. Haraway's complex theoretical book abounds in ideas and interpretations. It also outlines concrete actions, at local and regional levels that are situated, 'partial', that is to say, contextualised -as proof of the possible actions of 'art/science activisms […]' aimed at 'multispecies resurgence […] a recuperation […]' that would be part of response through our abilities, 'response-abilities' (Haraway 2016, 1;5;16). In Latour's view, faced with the 'reaction of the earth system' that began after the 70 post-war years that specialists called the 'Great Acceleration' (Latour 2017, 76), 'we need to reinvent everything all over again -the law, politics, the arts, architecture, cities. But -and this is stranger still -we also need even to reinvent movement, the vector of our actions. We need not forge ahead into the infinite, but learn to step back, to unplug, in the face of the finite. […]'. It is a quite clear political position, where the 'violence of the power struggle between the Extractors' (over-exploiters of the earth's resources) 'and the Menders' (the 'terrestrials' or repairers) is at play (Latour 2021, 155-157). So of course, if 'recuperation is still possible, but only in multispecies alliance, across the killing divisions of nature, culture, and technology and of organism, language, and machine' (Haraway 2016, 118), then it is nevertheless very difficult to go from philosophy to the field, and especially to find among our interlocutors in civil society the forces and means to concretely take up these challenges of 'assemblages' [START_REF] Tsing | The Mushroom at the End of the World: On the Possibility of Life in Capitalist Ruins[END_REF] that almost smack of utopia.

The Pessimistic View

Soraya Boudia and Nathalie Jas's vision is much more pessimistic (2019). After having sketched the history of the governance of the toxic world, which they divide into three forms (governance through control, governance through risk, and governance through adaptation), they rather condemn this policy of rehabilitation, maximum adaptability, and resilience. Because 'it is no longer a matter of rehabilitating damaged sites-something that has hardly ever been done satisfactorilybut rather to rehabilitate life possibilities on permanently contaminated lands'. And it is the 'populations living on contaminated lands [that] must learn to show resilience, to reinvent themselves and move forward despite the problems they face'. This government of adaptation 'contributes to normalising, or more precisely "naturalising", not only serious accidents but also ongoing contaminations that are often less immediately perceptible. This naturalisation process makes it possible not to single out those responsible for pollution bringing about visible and less visible catastrophes, and not to determine the deep causes of these'. The axe abruptly falls on this 'staying with' policy. Because by 'overemphasising the adaptability of individuals and populations […] these policies are not devoid of cynicism' (Boudia and Jas 2019, 89-92). The portrait they sketch of the situation is therefore rather sombre, as they explain: 'Sombre because of the scale of the environmental pollutions described by many scientific texts […]; Sombre also because of the cynicism of certain actors who try to ignore or cover up the damaging effects of their activities. Sombre finally because of the inability of various committed mobilisations and implemented regulations to curb this movement over the long term' (Boudia and Jas 2019, 95). In her quite chilling book, Lucie Taïeb (2020) tells the story of the human remains of the attack on the Twin Towers, mixed with garbage at the former Staten Island dump, which is in the process of becoming a large public park with recreational space for children. She describes her guided tour of the site, where the process of confining and capping the dump, through successive layers of materials possessing specific properties, is described to visitors. Depressed, Taïeb adds: 'Now everything is repaired, and this is the only consolation for all of the evil we know. The wounded earth is infinitely resilient, and memory is plastic. Shame and blemishes are erased. […] Everything is repaired and everything is erased; yet nothing disappears' 3 (Taïeb 2020, 76).

Unwanted Legacy in Estarreja

A Logical Continuum of Heritage Studies

Since it has been recognized that 'heritage comes also in diverse 'negative' forms, such as environmental pollution, social inequalities, and poverty, inherited from the past and having a myriad of impacts in the present,' other definitions of heritage have been included in 'a logical continuum […] of this subfield of heritage studies' [START_REF] Thomas | Dark Heritage[END_REF]. [START_REF] Wollentz | Toxic Heritage: Uncertain and Unsafe[END_REF], first proposed a definition of toxic heritage: 'we use the term "toxic heritage" to describe instances in which forms of difficult heritage come to endanger certain core values in society (such as equal rights and opportunities, peaceful coexistence, freedom of speech, health, and wellbeing), most often because of a lack of responsible management' (Wollentz et al. 2020, 299). In this book, Kryder-Reid and May (2024) are using the term toxic heritage to refer to the materiality of toxic substances, focusing on literal meanings; and connecting that history of harm with both formal heritage institutions and informal memory practices. Can toxic material be heritage? What does framing toxic sites as heritage offer? How are toxic sites remembered or, conversely, erased in the memory practices of communities and in official heritage narratives such as museums and historic markers? Are some of the questions asked in this volume (Kryder-Reid and May 2024).

Toxic Materials

Estarreja 4 falls within the definition of toxic heritage explored in this collection (Kryder-Reid and May, 2023) and also partly in the other framework [START_REF] Wollentz | Toxic Heritage: Uncertain and Unsafe[END_REF]. A chemical facility has existed there since the 1950s, one that discharged tons of toxic chemical products into the environment (earth, water, air) without oversight until the 1990s. Among the toxic materials found there, 'the most common pollutants are sulphur oxides and nitrogen oxides, ammonia, mononitrobenzene, suspended solids and vestiges of heavy metals, particularly arsenic and mercury. Liquid effluents include aniline, ammonium, benzene, mononitrobenzene, arsenic, iron, zinc and lead. In general, the liquid effluents originating from the chemical facility's factories (whether or not they have undergone pre-treatment) end up in two ditches (those of São Filipe and Breja) leading to their final destination (the Esteiro de Estarreja) […]' (Barrosa 1985 quoted by [START_REF] Azevedo | Contribuição para a caracterização ambiental da área envolvente do complexo químico de Estarreja[END_REF]). The superficial and groundwater are contaminated and will remain so, apparently due to a lack of possible treatments and their costs. But this water is still used to irrigate maize (and adjacent plants like gourds and beans in backyard gardens), being easily accessible through pumping from wells. 5 In response to our questions, the city health department asked us to systematically remind inhabitants not to drink the well water -implicitly revealing a habit acquired by some people.

Danger to human (and animal) health, therefore, seems real and existent -yet research into miscarriages, for example, has not succeeded in proving a higher incidence in Estarreja than elsewhere [START_REF] Valente | Environmental Pollution and Human Health: Exploring Adverse Pregnancy Outcomes and Food and Water Consumption in Estarreja Municipality, Portugal[END_REF].

The Materiality of Toxic Substances

From the institutions, there exists a certain kind of silenced information and a choice about which type of past to promote. On the developed bank of the Esteiro de Estarreja, whose underwater sludge has been proven to be contaminated with arsenic and mercury, a sign recalls the history of salt shipping by boat from the sea to the city. It provides information about the lagoon's pre-1950s social and trade history. But nothing is said about the toxic sediments it has retained, which were discharged by factories after the 1950s and are still dangerous; nor about the ban on swimming there. This lack of warning signs, which shocked us in 2016, was viewed by some members of the team as deliberate concealment from tourists, who are very numerous in this region. This was also observed near the Largo do Laranjo, another area heavily polluted by mercury, where the banks have been attractively developed into cyclable paths, without any signs warning about the dangerousness of the sludges in the deep water. But according to the biology teachers at the high school in Estarreja, it seems that a lack of information is notorious in that area, where (illegal) shellfish divers take risks that pose a threat not just to themselves, but also to the environment, by digging up sludge full of heavy metals. The town council prefers to emphasise a rich history of salt and of algae harvesting (moliço) instead of stressing the more recent unwanted legacy, which is damaging to its image. 6 All the more so since it actively intervenes to repair the environment. It also seems that the contamination of the environment is a legacy that can cross generations, regardless of the attitude of the population and their point of view on this contamination. The unwanted legacy seems accepted, with resilience (Boudia and Jas 2019).

Remediation and Memory of the Milieu

Legacy versus Heritage

Actually, in Estarreja, the fieldwork did not lead us to heritage or toxic heritage but remediation. Through sponsored interventions at different scales from local to international, the physical and environmental recovery of contaminated spaces is ongoing. In the past, this has already been applied to two solid waste dumps. In the older one (Parque de Lamas), mercury sludge dumped on permeable sands has been covered over, using only lime. This space remains open and easily accessible to the public. Motocross bike tracks are visible on it. The other one (Aterro de Cinzas brancas) retains other toxic sludges under a waterproof plastic film. Covered in the soil, it forms a sloping hill surrounded by a fence, access to which is prohibited or restricted. Both are adjacent to the factories, far from the flagship remediation operation on a former liquid waste spillway, a wetland that is today called BioRia. Through phytoremediation -controlled cooperation between species, the basic rule of 'making-with' (Haraway 2016) -and Phragmites australis, a plant that is already abundant in that lagoon, the lands caught in the roots are gradually being decontaminated. A refuge for birds and hikers with its wild and/or cultivated lands interspersed with water channels, some of which are navigable, the BioRia is today the pride of the city council and people of Estarreja, a natural heritage 7 whose interpretation centre and mascot have been set up as symbols of clean, sustainable renewal. The interpretation centre stresses biodiversity and suggested walks. No link is made with the area's industrial history.

Recovery of a Contaminated Ditch

The last regeneration programme concerns the removal of contaminated soil from one of the drainage ditches, carried out in 2021. This ditch (Vala de São Filipe)

crosses woodland, land cultivated with maize, and a hamlet. Its course ends in the Esteiro de Estarreja, which itself belongs to the water network of the whole of the Ria de Aveiro. In 100 days the ditch was cleaned out; its soil was removed to a depth of 40 cm and transported by truck to a decontamination centre near Lisbon; then a geotextile fabric and heavy rocks were placed on the bottom. Contaminated soil was also removed from the verges, up to a width of 5 metres, and arable replacement soil was added for cultivated fields. The ditch is now paved, and this is supposed to prevent all possible contact with pollution, especially for the people who had the routine of scrubbing it after winter. It will prevent neither the grasses from growing there again nor the still-contaminated groundwater from overflowing during heavy rain. But it contains and represents the space, it warns through its restoration, it informs, it protects.

A Border Case

On the area's memory, traces and a few scars, therefore, remain: old abandoned factories; still contaminated groundwater; an unmissable white mountain of lime; a sloping hill almost forgotten; a crossing line that will fade into the vegetation over time; a mended and maintained walking space set up as natural heritage. Underneath or inside, the materials remain [START_REF] Storm | Post-Industrial Landscape Scars[END_REF]. The toxic sites of Estarreja are neither remembered nor erased. Belonging to the landscape, they are gradually decontaminated or confined. As things stand, they are not subject to any interpretation, or any reflexivity on history, nor do they serve as strategies of resistance or restorative justice. Estarreja appears as a border case, a situation where the question of toxic heritage is not yet asked by the institutions. Only a natural heritage is praised and protected.

Habituation and Activatable Memory

The City's Image

The reconstruction of Estarreja is also societal. In 2001, the PACOPAR was created, a multi-actor consortium grouping the five active chemical factories (Air Liquide, AQP, Cires, Bondalti and Dow), to establish connections with the main entities of civil society, including the city council, the firemen, the health centre, the schools, the University of Aveiro, and the ecological Cegonha association. This institutional and political coming-together supports the factories' desire for transparency and goodwill, and its members' common aim of applying Responsible Care principles, for a 'sustainable development of Estarreja and the world, by linking economic development with the protection of the environment and health' (CME 2010). In a sense, the PACOPAR is trying out a societal and environmental makingwith, and it was awarded a prize for this in 2005. During its regular meetings, it also distributes grants for the city's educational and cultural activities, as well as for environmental research. It is in this context of physical and political reconstruction that Estarreja is managing the present time of its still-active chemical facility. And this might be the reason why, unlike other industrial cities, Estarreja does not seem prone to turn its factories into a potential social or cultural heritage that can be valorised, nor to repurpose some of them [START_REF] Berger | Industrial Heritage and the Ambiguities of Nostalgia for an Industrial Past in the Ruhr Valley, Germany[END_REF]. Having a cinema/theatre, a library, several museums, a jazz festival and an urban art festival, its rich artisticcultural program somewhat systematically bypasses any reference to the factories.

There is no mural painting representing the industrial part of the city, nor any existing book about the history of the chemical facility. The unwanted legacy is not a source of pride. It remains a heavy burden. Its valorisation is not on the agenda.

Neither is its patrimonialisation. In the booklet for the 2020 ESTAU Urban Art Festival, Estarreja is presented as the hometown of Egas Moniz (1949 Nobel Prize in Medicine) and as a unique biodiversity zone with the BioRia. 8

The Worrying Comes from Others

On the other hand, the neighbouring University of Aveiro just 20 kilometres away has an obvious interest in the chemical facility. Since its creation in 1973, much research has been conducted at Estarreja, and academic theses and publications in biology, geoscience, toxicology and other fields abound. Since 2010, an Observatoire Hommes-Milieux receiving funding from France (Labex Driihm-CNRS-INE) has been reinforcing this research laboratory. Yet, very few of the results get back to the local population -the requirement that academics write in English being one of the reasons. A book The Factory and the Life should soon be published in Portuguese. This collection of interviews with former workers of the chemical facility shows that a social and rather kindly memory is accessible and activatable. 9 The film we created [START_REF] Giongo | SAFE -Social Awareness for Environment in Estarreja[END_REF]) also features workers with fairly happy memories associated with economic prosperity and pride in not having been obliged to emigrate or live in agriculture. The relationship with the dangers is more complex. Unsurprisingly, however, the worrying comes from others: the closer one stands to the epicentre, the less one's awareness of danger is activated -or activatable [START_REF] Beck | World Risk Society[END_REF]. Without any denial of the existence or futile resistance, there is something like necessary habituation to an evil accepted as necessary. The film also presents the citizen science project CITAQUA 10 , which, by linking the university, the locals and the schools, succeeded in raising awareness, as well as teaching (particularly adolescents) about other contamination sources in the water of private wells, with a focus on nitrate levels. The monitoring of 27 wells by their owners using measurement kits distributed by this academic project made some users realise that they could no longer use well water for domestic purposes. Awareness among citizens of the groundwater quality and its vulnerability was increased. The fact that political decision-makers could now seize upon that successful action to distribute kits to well owners would magnify that principle of making-with, and also ensures prevention and information, quite obviously. Schoolchildren also benefit from a few air quality awareness-raising sessions, in which they are asked fun questions for example. At the same time, thanks to university funding, extra air-measurement sensors have been installed, able to supply tangible indicators for research. 11 It is not yet a matter of scientific-artistic activism, like Pigeon Blog, which involves civil society, artists, and pigeons equipped with air quality sensors that can take readings on the ground and at various heights in the sky (Haraway 2016, 37), but maybe it should get to that point someday.

A Kind of Balance

Because although actions are being carried out with a civil society receptive to awareness-raising programmes, these people prove to be more resistant to the possibility of self-organising to create an opposition force, or simply a monitoring force. Estarreja's only ecological association, created in the 1990s to (successfully) fight the government's decision to locate a very polluting waste incinerator in Estarreja has almost no members today. Therefore, whether sufficiently informed or not, the population seems as if it is 'staying with' the chemical facility. There is no silenced memory, nor any memory or recollections activated by the municipality (at the risk of losing them) with a view to possible patrimonialisation. No one seems to have taken possession of a certain history, neither the city council, nor the factories, nor civil society, nor even a historian. Therefore, it seems that some kind of balance has been established in Estarreja, through habituation that takes comfort in turning around the city's image through concrete environmental regeneration actions, and through the energy invested in sociocultural activities that make the city attractive and pleasant to live in. A rotten peace? 12 Maybe. But between acceptance of a toxic heritage that -in a certain way -attributes an active recognition to pollution, and the gradual recovery of an unwanted legacy of which no one wants to be the standard-bearer, the choice seems to have been made.

Conclusion

Estarreja is neither Flammable in Argentina [START_REF] Auyero | Flammable: Environmental Suffering in an Argentine Shantytown[END_REF] nor even Lubrizol in France (Izoard 2020). Fortunately, no serious accident occurred at this location. Estarreja is only one case among many others where, after the euphoria of full employment thanks to factories, the damage to the environment and health now has to be repaired. Estarreja is also not in a post-industrial context, where a form of nostalgia for the past could unfold [START_REF] Storm | Post-Industrial Landscape Scars[END_REF][START_REF] Berger | Industrial Heritage and the Ambiguities of Nostalgia for an Industrial Past in the Ruhr Valley, Germany[END_REF]. Quite the contrary. In August 2022, one of the complex's powerful entrepreneurs announced in the press that the contract between the chemical plants had just been renewed for 15 years because their competitiveness in hydrogen production technologies was ensured (Expresso, 19/08/2022). Industrialists, city councils and people continue to rely on the chemical and industrial complex for the future, in terms of dynamic economic production and jobs. 13 What is perceived today in Estarreja is a toxic legacy, which leads to environmental repair operations. What is not formalized is the existence of a toxic heritage, which from the past to the future is irreversibly inscribed in this place: no local historian, citizen association or municipal actions seems (yet?) to think of the place in terms of memory or heritage. The case of Estarreja shows that material toxicity is not synonymous with negative associations and that 'habituation' can be useful in thinking about how toxic heritage intersects memory practices. Unfortunately, conceptualising toxicity as heritage does not tend to resolve real problems, like spatiotemporal, political and institutional differences. While on the one hand, there is recovery, generally in advanced economies, on the other hand, there is our own recovered and ever-accumulating waste (toxic materials, technology, clothing …) in emerging countries, sent there by land, air and sea -that social and environmental injustice that is much evoked, but that we are only maintaining and reinforcing. While discourse here is in favour of green environmental protection technologies, over there, where others live, discourse concerns the 'extremely polluting extraction of those many metals that those green technologies need for their production, carried out under conditions that are catastrophic for workers and residents living near the production sites, and will soon end up as waste for which we have no solution available -nor is any being studied' (Boudia and Jas 2019, 96). There are also gaps between the university and the insufficient return of research to locals; between philosophical thought and actors in the field. Our contribution appears here as a border case for this volume devoted to Toxic Heritage and Heritage Studies. It responds more directly to research on repair and species alliances -as suggested in the introduction. With success, BioRia has become that dynamic environmental and ecological patch evoked by [START_REF] Tsing | The Mushroom at the End of the World: On the Possibility of Life in Capitalist Ruins[END_REF]. Are we 'capable, with each other in all of our bumptious kinds, of response?' (Haraway 2016, 1). Let us hope that operations to minimize damage to health and the environment continue; that no chemical accident ever occurs; and that one day, perhaps, once all chemical and industrial activities have ceased, a human memorynot just a memory of the milieu -is developed there. 4 A mixed territory with 27,000 inhabitants, including the chemical facility, an urban centre, hamlets, and rural areas with breeding, horticulture, and cereal farming. 5 Research conducted by the University of Aveiro proved that mercury was retained in the maize roots but did not get into the grain. On the other hand, nothing has been confirmed about the associated plants [START_REF] Cabral-Pinto | Human Health Risk Assessment Due to Agricultural Activities and Crop Consumption in the Surroundings of an Industrial Area[END_REF]). 6 However, very high financial damages that are not without importance in many ways are repaid by the factories. In fact, every industrial site pays compensation to the municipalities. We do not yet have these figures for Estarreja. 7 Title of the book published by the city council of Estarreja ( CME 2010). 8 See also [START_REF] Silva | O BioRia e a Construção da Imagem de Estarreja[END_REF]. 9 Elisabeth Figueiredo (Dir.), Labex Driihm 2015. See [START_REF] Figueiredo | Não Queriam Que Ninguém Soubesse Que Era Uma Fábrica Perigosa» -Narrativas Dos Trabalhadores Do Complexo Químico de Estarreja Sobre Os Riscos No Trabalho e a Sua Evolução[END_REF]. 10 Daniela Figueiredo (Dir.), Labex Driihm 2015. See the first results in De [START_REF] De Figueiredo | Groundwater Quality Monitoring by Local Citizens at a Small Town[END_REF]. 11 Myriam Lopes (Dir.), Labex Driihm 2018. See the first results in [START_REF] Reis | Accident Scenario Modelling with Hazardous Materials in Transportation Infrastructures[END_REF]. 12 Criticism made by PACOPAR through one of the people interviewed in 2016. See the verbatim statement in [START_REF] Wateau | Entre Terre et Eau Contaminées: Populations, Institutions et Perceptions Du Risque[END_REF]. 13 It would be 3,000 direct and indirect jobs (Expresso. August 19, 2022). De Mello.

FIGURE 11

 11 FIGURE 11.2 A well for irrigation next to the factories. Photograph by Carmem Giongo 2019.

FIGURE 11 . 3

 113 FIGURE 11.3 BioRia mascot. Photograph by Fabienne Wateau 2016.

FIGURE 11 . 4

 114 FIGURE 11.4 Paving of the ditch in the hamlet. Photograph by Fabienne Wateau 2021.

FIGURE 11 . 5

 115 FIGURE 11.5 Air quality awareness-raising with school children. Photograph by Fabienne Wateau 2019.

Notes1

  Respectively: Regional Prize in the 'Environment' category of the first edition of the Annual Tourism Prizes, awarded by Turismo da Rota da Luz; 'For the example of innovation, transparency and success in relations between the chemical industry and the community' ( CME 2010). 2 This ongoing research has benefited from several sources of financing: from the Labex Driihm (Dispositif de Recherche Interdisciplinaire sur les Interactions Hommes Milieux) CNRS-INE, in 2016 and 2019; from the Labex PP (les Passés dans le présent) CNRS-INSHS in 2020; from the MSH-Mondes (for the film SAFE) in 2019; from SMI (Soutien à la mobilité internationale) of the INSHS CNRS in 2021. It has been conducted collectively by all of the co-authors, under the supervision of the first author of the article. The team unites several fields: social anthropology, psychology, geography, biology and environmental engineering. 3 On the positive role of forgetting see this volume (May 2024).

Fabienne Wateau et al.

Fabienne Wateau et al.