UPR HortSys, Cirad, F-97285, Le Lamentin, Martinique, France.
HortSys, Geco, Univ Montpellier, Cirad, Inra, Inria, Montpellier SupAgro, Montpellier, France.
Environ Sci Pollut Res Int. 2020 Nov;27(33):40999-41013. doi: 10.1007/s11356-019-06247-y. Epub 2019 Aug 23.
Chlordecone, applied on soils until 1993 to control banana weevil, has polluted water resources in the French West Indies for more than 40 years. At the watershed scale, chlordecone applications were not homogenous, generating a spatial heterogeneity of the pollution. The roles of climate, hydrology, soil, agronomy, and geology on watershed functioning generate a temporal heterogeneity of the pollution. This study questions the interactions between practices and the environment that induce such variability. We analyzed hydrological and water pollution datasets from a 2-year monitoring program on the Galion watershed in Martinique (French West Indies). We conjointly analyzed (i) weekly chlordecone (CLD) concentration monitored on 3 river sampling sites, (ii) aquifer piezometric dynamics and pollutions, and (iii) agricultural practices on polluted soils. Our results showed that chlordecone pollution in surface waters are characterized by annual trends and infra-annual variations. Aquifers showed CLD concentration 10 times higher than surface water, with CLD concentration peaks during recharge events. We showed strong interactions between rainfall events and practices on CLD pollution requiring a systemic management approach, in particular during post-cyclonic periods. Small sub-watershed with high CLD pollution appeared to be a substantial contributor to CLD mass transfers to the marine environment via rivers and should therefore receive priority management. We suggest increasing stable organic matter return to soil as well as external input of organic matter to reduce CLD transfers to water. We identified hydrological conditions-notably drying periods-and tillage as the most influential factors on CLD leaching. In particular, tillage acts on 3 processes that increases CLD leaching: organic matter degradation, modification of water paths in soil, and allophane clay degradation.
氯丹曾被用于 1993 年之前的土壤，以防治香蕉象鼻虫，这导致法属西印度群岛的水资源被污染了 40 多年。在集水区尺度上，氯丹的使用并不均匀，导致了污染的空间异质性。气候、水文学、土壤、农学和地质学在集水区功能上的作用产生了污染的时间异质性。本研究探讨了导致这种变异性的实践和环境之间的相互作用。我们分析了法属西印度群岛马提尼克岛加里昂流域为期两年的监测计划中的水文和水污染数据集。我们共同分析了（i）在 3 个河流采样点监测的每周氯丹（CLD）浓度，（ii）含水层测压动态和污染，以及（iii）受污染土壤上的农业实践。我们的结果表明，地表水的氯丹污染具有年度趋势和亚年度变化。含水层中的氯丹浓度比地表水高出 10 倍，在补给事件期间出现氯丹浓度峰值。我们表明，降雨事件与污染治理之间存在强烈的相互作用，需要采取系统的管理方法，特别是在气旋过后的时期。高氯丹污染的小次流域似乎是通过河流向海洋环境转移氯丹物质的重要贡献者，因此应优先管理。我们建议增加稳定的有机质返回土壤，以及外部有机质输入，以减少氯丹向水体的转移。我们确定了对氯丹淋溶最有影响的因素，包括水文条件（特别是干旱期）和耕作。特别是，耕作作用于三个增加氯丹淋溶的过程：有机质降解、土壤中水流路径的改变以及水铝英石粘土的降解。
