Due to the persistent pollution of soils by an organochlorine, chlordecone (CLD also known as Kepone ©) in the French West Indies, some crops may be contaminated beyond the European regulatory threshold, the maximum residue limit (MRL). Farmers need to be able to foresee the risk of not complying with the regulatory threshold in each field and for each crop, if not, farmers whose fields are contaminated would have to stop cultivating certain crops in the fields concerned. To help farmers make the right choices, we studied the relationship between contamination of the soil and contamination of crops. We showed that contamination of a crop by CLD depended on the crop concerned, the soil CLD content and the type of soil. We grouped crop products in three categories: (i) non-uptakers and low-uptakers, (ii) medium-uptakers, and (iii) high-uptakers, according to their level of contamination and the resulting risk of exceeding MRL. Using a simulation model, we computed the soil threshold required to ensure the risk of not complying with MRL was sufficiently low for each crop product and soil type. Threshold values ranged from 0.02 ?gkg?1 for dasheen grown in nitisol to 1.7 ?gkg?1 for yam grown in andosol in the high-uptake category, and from 1 ?gkg?1 for lettuce grown in nitisol to 45 ?gkg?1 for the leaves of spring onions grown in andosol in the medium-uptake category. Contamination of non-uptakers and low-uptakers did not depend on soil contamination. With these results, we built an easy-to-use decision support tool based on two soil thresholds (0.1 and 1 ?gkg?1) to enable growers to adapt their cropping system and hence to be able to continue farming. (Résumé d'auteur)tttttt

When field pollution is heterogeneous due to localized pesticide application, as is the case of chlordecone (CLD), the mean level of pollution is difficult to assess. Our objective was to design a decision support tool to optimize soil sampling. We analyzed the CLD heterogeneity of soil content at 0-30- and 30-60-cm depth. This was done within and between nine plots (0.4 to 1.8 ha) on andosol and ferralsol. We determined that 20 pooled subsamples per plot were a satisfactory compromise with respect to both cost and accuracy. Globally, CLD content was greater for andosols and the upper soil horizon (0-30 cm). Soil organic carbon cannot account for CLD intra-field variability. Cropping systems and tillage practices influence the CLD content and distribution; that is CLD pollution was higher under intensive banana cropping systems and, while upper soil horizon was more polluted than the lower one with shallow tillage (<40 cm), deeper tillage led to a homogenization and a dilution of the pollution in the soil profile. The decision tool we proposed compiles and organizes these results to better assess CLD soil pollution in terms of sampling depth, distance, and unit at field scale. It accounts for sampling objectives, farming practices (cropping system, tillage), type of soil, and topographical characteristics (slope) to design a relevant sampling plan. This decision support tool is also adaptable to other types of heterogeneous agricultural pollution at field level. (Résumé d'auteur)

Chlordecone (CLD), an organochlorine insecticide, and other persistent organic pollutants continue to contaminate the environment worldwide and have adverse effects on human health through food exposure. Cucurbitaceae take up weathered hydrophobic pollutants from the soil and translocate them to their shoots. As Cucurbitaceae are an important part of the diet in the French West Indies, they are among the main contributors to total dietary intake of CLD. We analyzed the contamination by CLDs (CLD and 5b-hydroCLD) of four cucurbits grown in the field and/or in the greenhouse. Different physiological (crop species) and environmental (soil type, growth conditions) variables were shown to influence uptake of the pollutant from the soil by the crop. Cucurbita species (zucchini and pumpkin) were more contaminated than Cucumis sativus (cucumber), and Sechium edule (christophine or chayote) translocated CLDs to fruits very poorly compared with cucumber and pumpkin. Greenhouse conditions and non-allophanic (nitisols and ferralsols) soils favored plant contamination more than field conditions and allophanic soils (andosols). (Résumé d'auteur)

Chlordecone was applied between 1972 and 1993 in banana fields of the French West Indies. This resulted in long-term pollution of soils and contamination of waters, aquatic biota, and crops. To assess pollution level and duration according to soil type, WISORCH, a leaching model based on first-order desorption kinetics, was developed and run. Its input parameters are soil organic carbon content (SOC) and SOC/water partitioning coefficient (Koc). It accounts for current chlordecone soil contents and drainage water concentrations. The model was valid for andosol, which indicates that neither physicochemical nor microbial degradation occurred. Dilution by previous deep tillages makes soil scrapping unrealistic.Lixiviation appeared the main way to reduce pollution. Besides the SOC and rainfall increases, Koc increased from nitisol to ferralsol and then andosol while lixiviation efficiency decreased. Consequently, pollution is bound to last for several decades for nitisol, centuries for ferralsol, and half a millennium for andosol.

Chlordecone was applied between 1972 and 1993 in banana fields of the French West Indies. This resulted in long-term pollution of soils and contamination of waters, aquatic biota, and crops. To assess pollution level and duration according to soil type, WISORCH, a leaching model based on first-order desorption kinetics, was developed and run. Its input parameters are soil organic carbon content (SOC) and SOC/water partitioning coefficient (Koc). It accounts for current chlordecone soil contents and drainage water concentrations. The model was valid for andosol, which indicates that neither physico-chemical nor microbial degradation occurred. Dilution by previous deep tillages makes soil scrapping unrealistic. Lixiviation appeared the main way to reduce pollution. Besides the SOC and rainfall increases, Koc increased from nitisol to ferralsol and then andosol while lixiviation efficiency decreased. Consequently, pollution is bound to last for several decades for nitisol, centuries for ferralsol, and half a millennium for andosol. Soil and water contamination by chlordecone will persist for several centuries in the French West Indies, because the only decontamination is through leaching by drainage water.

Mercury (Hg) concentrations have significantly increased in oceans during the last century. This element accumulates in marine fauna and can reach toxic levels. Seafood consumption is the main pathway of methylmercury (MeHg) toxicity in humans. Here, we analyzed total Hg (T-Hg) concentrations in two oceanic squid species (Ommastrephes bartramii and Thysanoteuthis rhombus) of an increasing commercial interest off Martinique, French West Indies. Stable isotope ratios reveal a negative linear relationship between δ¹⁵N or δ¹³C in diamondback squid samples. No significant trend was observed between δ³⁴S values and T-Hg concentrations, contrasting with the sulfate availability and sulfide abundance hypotheses. This adds to a growing body of evidence suggesting Hg methylation via sulfate-reducing bacteria is not the main mechanism driving Hg bioavailability in mesopelagic organisms. All squid samples present T-Hg levels below the maximum safe consumption limit (0.5 ppm), deeming the establishment of a commercial squid fishery in the region safe for human consumption.

Chlordecone is an organochlorine pesticide, used in the Lesser Antilles from 1972 to 1993 to fight against a banana weevil. That molecule is very persistent in the natural environment and ends up in the sea with runoff waters. From 2003 to 2013, seven campaigns of samplings have been conducted to evaluate the level of contamination of fish, crustaceans, and mollusks. The present study is the first assessment and the first comparison of the concentrations of chlordecone between marine areas, taxonomic groups, and ecological factors like trophic groups or preferential habitat of fish species. The four most contaminated marine areas are located downstream the contaminated rivers and banana plantations. Crustaceans seemed to be more sensitive to the contamination than fish or mollusks. Finally, when comparing contamination of fish according to their ecology, we found that fish usually living at the border of mangrove and presenting detritivores-omnivores diets were the most contaminated by chlordecone. These results are particularly useful to protect the health of the local population by controlling the fishing and the commercialization of seafood products, potentially contaminated by chlordecone.

Massive Sargassum beachings occurred since 2011 on Caribbean shores. Sargassum inundation events currently involve two species, namely S. fluitans and S. natans circulating and blooming along the North Atlantic subtropical gyre and in the entire Caribbean region up to the Gulf of Mexico. Like other brown seaweeds, Sargassum have been shown to bioaccumulate a large number of heavy metals, alongside with some organic compounds including the contamination by historical chlordecone pollution in French West Indies (FWI), an insecticide used against the banana’s weevil Cosmopolites sordidus. The present study reports, during two successive years, the concentration levels of heavy metals including arsenic in Martinique and Guadeloupe (FWI). We found that Sargassum can also accumulate a high concentration of chlordecone. Sargassum contamination by chlordecone is observed in areas close to contaminated river mouth but can be partly due to chlordecone desorption when secondary drifted on chlordecone-free shore. Our results further demonstrate that algae bleaching raises a number of questions about inorganic and organic pollutant (i) bioaccumulation, at sea for arsenic and close to river plumes for chlordecone, (ii) transport, and (iii) dissemination, depending the shoreline and the speciation for arsenic and/or metabolization for both.

Over the last decade, increasing proliferations of Atlantic Sargassum populations have led to massive beaching with disastrous environmental consequences. This study is a preliminary assessment of open ocean Sargassum spp. element concentration to assess their potential contribution on coastal ecosystems. Sargassum spp. samples from seven sites, collected along a transect from the center of the Atlantic Ocean to near the coast of Martinique (French West Indies), were analyzed to determine their potential metal and metalloid enrichment. Mean element concentrations from the Sargassum spp. samples were ranked in the following descending order: As > Fe > Mn > Al > Zn > V > Ni > Cu > Cr > Cd > Hg. Element concentrations are relatively low compared to previous results of beached Sargassum spp. except for As that need to be carefully considered before reusing Sargassum spp.