Long-term pollution by chlordecone of tropical volcanic soils in the French West Indies: A simple leaching model accounts for current residue

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 (K_oc). 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, K_oc 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.     

应用EQC模型评估灭蚁灵和十氯酮的环境归趋

应用EQC模型评估了灭蚁灵和十氯酮在多介质环境中的行为和归趋. 结果表明,在稳定平衡状态下,灭蚁灵和十氯酮在土壤相中的残留率分别达95.6%和94.5%;在稳定非平衡状态下,灭蚁灵除直接排放到大气相、十氯酮除直接排放到水体相中外,还分别约有38%残留在排放相外,它们在大气相和水体相中的浓度水平和质量分布均很低,在沉积物相中则来自于水体相向沉积物相的沉降. 灭蚁灵主要通过大气相的水平迁移以及大气相和土壤相中的化学反应降解输出;十氯酮则主要通过水体相的水平迁移和土壤相的厌氧反应降解输出. 灭蚁灵的主要界面迁移过程是水体相向沉积物相的沉降,其次是沉积物相向水体相的扩散;十氯酮则是大气相向土壤相的迁移,其次是水体相向沉积物相的沉降和大气相向水体相的迁移.      

Determination of soil content in chlordecone (organochlorine pesticide) using near infrared reflectance spectroscopy (NIRS)

Chlordecone is a toxic organochlorine insecticide that was used in banana plantations until 1993 in the French West Indies. This study aimed at assessing the potential of near infrared reflectance spectroscopy (NIRS) for determining chlordecone content in Andosols, Nitisols and Ferralsols from Martinique. Using partial least square regression, chlordecone content conventionally determined through gas chromatography–mass spectrometry could be correctly predicted by NIRS (Q² = 0.75, R² = 0.82 for the total set), especially for samples with chlordecone content <12 mg kg⁻¹ or when the sample set was rather homogeneous (Q² = 0.91, R² = 0.82 for the Andosols). Conventional measures and NIRS predictions were poorly correlated for chlordecone content >12 mg kg⁻¹, nevertheless ca. 80% samples were correctly predicted when the set was divided into three or four classes of chlordecone content. Thus NIRS could be considered a time- and cost-effective method for characterising soil contamination by chlordecone.