DataSheet1_Organochlorine Compounds in Beached Plastics and Marine Organisms.docx

Here we compare bioaccumulation factors in marine organisms to partition ratios in marine debris for dichlorodiphenyltrichloroethane and polychlorinated biphenyls. Both organochlorines are synthetic persistent organic pollutants emitted into the environment since the beginning of the last century in approximately equal amounts. Their vast use and dispersion have resulted in approximately similar median concentrations of the two organochlorines in some pelagic organisms, namely in the liver and muscle tissue of fish. Molluscs, on the other hand, show higher median uptake of PCBs (median = 2.34 ng/g) than of DDTs (median = 1.70 ng/g), probably reflecting more localized conditions. We found that the bioaccumulation factors can be several orders of magnitude higher than the partition ratios. For instance, the median concentrations of organochlorines in the different matrices of fish, birds, and mammals are between one to four orders of magnitude higher than those found in marine debris, when lipid-normalized; or up to two orders of magnitude when measured as wet-weight. But, in molluscs, bioaccumulation/partition equals unity, which agrees with previous studies using passive samplers. Future research should focus on reducing sources of uncertainty by 1) homogenization of chemical procedures; 2) better assessment of chemical partition equilibrium between water and polymers in environmental conditions; 3) use of (multi)polymer passive samplers better aimed at mimicking uptake of specific living tissues.

本研究针对二氯二苯基三氯乙烷（dichlorodiphenyltrichloroethane, DDT）与多氯联苯（polychlorinated biphenyls, PCBs），对比海洋生物体内的生物富集因子（bioaccumulation factors）与海洋碎屑中的分配比。两类化合物均为人工合成的持久性有机污染物（persistent organic pollutants, POPs），自20世纪初起被排放至环境中，且初始排放量大致相当。二者的大规模使用与广泛扩散，使得部分远洋生物（如鱼类的肝脏与肌肉组织）中这两类有机氯的中位浓度大致相近。
但软体动物的多氯联苯中位摄取量（中位值=2.34 ng/g）高于滴滴涕类（中位值=1.70 ng/g），这或许反映了其所处环境的局地性特征。本研究发现，生物富集因子可比分配比高出数个数量级。例如，经脂质标准化处理后，鱼类、鸟类与哺乳动物不同组织基质中的有机氯中位浓度，较海洋碎屑中的浓度高出1至4个数量级；若以湿重计，则最高可高出2个数量级。而在软体动物中，生物富集/分配比等于1，这与此前采用被动采样器（passive samplers）开展的相关研究结果一致。
未来的研究应聚焦于通过以下途径降低不确定性来源：1）统一化学分析流程；2）更精准地评估环境条件下水体与聚合物间的化学分配平衡；3）采用（多）聚合物被动采样器，以更好地模拟特定生物组织的污染物摄取过程。