Briant Nicolas, Freydier Rémi, Araújo Daniel F, Delpoux Sophie, Elbaz-Poulichet Françoise
Ifremer, CCEM Contamination Chimique des Ecosystèmes Marins, F-44000 Nantes, France.
Laboratoire HydroSciences UMR 5569, CNRS, Université Montpellier, IRD, 163 rue Auguste Broussonnet, CC 57, 34090 Montpellier, France.
Sci Total Environ. 2022 Nov 25;849:157885. doi: 10.1016/j.scitotenv.2022.157885. Epub 2022 Aug 6.
The intensive use of copper (Cu) compounds as an alternative biocide in antifouling paints (APs) has resulted in wide Cu contamination into the marine environment, especially near marina harbor activities. In this work, the applicability of Cu isotopes to discriminate Cu origins related to the use of Cu-based APs in marine environments was tested. To this, Cu isotopes in APs, shipyard sludges, and sediment cores sampled in the Cu-contaminated Mediterranean marina of Port Camargue were determined. APs represent an important dominant anthropogenic source for metals in this site, making it ideal to test Cu isotopes as tracers. The overall isotope composition of four sediment cores and a surface sample varied between -0.13 and 0.44 ‰ (δCu relative to NIST-976). Selected APs brands show a similar Cu concentration ~0.15 % and δCu average of 0.54 ± 0.05 ‰. The plot of δCu vs concentration for all datasets allowed dissociating natural and APs end-members. However, sample isotope systematics were not consistent with a conservative mixing binary source process. Heavily Cu-contaminated sediments show isotope signatures lighter than APs brands. However, the most Cu-contaminated sample, located directly above the careening area, shows a δCu slightly lighter than APs (0.44 ‰ vs 0.54 ‰, respectively). Results suggest the preferential releasing of a heavy isotope pool by APs when these compounds are solubilized in seawater. The isotope fractionation was attributed to potential chemical Cu coordination changes during its elemental partition between paint and marina seawater and the fractionation induced by the organic ligands in the water column, before deposition. Further laboratory experiments are recommended to model the isotope fractionation mechanisms related to Cu release by APs. Because the APs' isotope signature is modified in marine environments, the use of Cu isotopes as tracers of AP in marine environments is challenging and needs more investigation.
在防污涂料（APs）中大量使用铜（Cu）化合物作为替代型杀生剂，已导致铜广泛污染海洋环境，尤其是在码头港口活动附近。在本研究中，测试了铜同位素用于区分海洋环境中与使用铜基防污涂料相关的铜来源的适用性。为此，测定了在受铜污染的卡马尔格港地中海码头采集的防污涂料、船厂污泥和沉积物岩芯中的铜同位素。防污涂料是该地点金属的一个重要主要人为来源，使其成为测试铜同位素作为示踪剂的理想场所。四个沉积物岩芯和一个表层样品的总体同位素组成在-0.13‰至0.44‰之间变化（相对于NIST - 976的δCu）。选定的防污涂料品牌显示出相似的铜浓度~0.15%，δCu平均值为0.54±0.05‰。所有数据集的δCu与浓度关系图能够区分天然和防污涂料端元。然而，样品同位素系统与保守混合二元源过程不一致。受铜严重污染的沉积物显示出比防污涂料品牌更轻的同位素特征。然而，位于倾侧区正上方的受铜污染最严重的样品，其δCu略轻于防污涂料（分别为0.44‰和0.54‰）。结果表明，当这些化合物溶解于海水中时，防污涂料优先释放重同位素库。同位素分馏归因于涂料与码头海水之间元素分配过程中潜在的化学铜配位变化，以及沉积前水柱中有机配体引起的分馏。建议进一步开展实验室实验，以模拟与防污涂料释放铜相关的同位素分馏机制。由于防污涂料的同位素特征在海洋环境中会发生改变，因此在海洋环境中使用铜同位素作为防污涂料的示踪剂具有挑战性，需要更多研究。
