海洋沉积物中酸溶硫化物对二价金属镉的地球化学特征及生物毒性的影响

通过海洋沉积物镉加标实验、沉积物间隙水分析和对加标沉积物毒性的10天底栖端足类生物检验，重点探讨在硫化物存在条件下，二介有毒金属镉在沉积物－间隙水系统中的地球化学分配和化学活性，及镉在沉积物中的化学活性与生物毒性间的关系。研究结果表明，镉加标沉积物的毒性与间隙水中镉浓度呈正相关，而与沉积物镉总量无关。在硫化物存在条件下，沉积物－间隙水系统中，二价镉在固、液两相同的分配主要受酸溶硫化物（AVS）影响。AVS归一化沉积物中二价镉含量可作为预测和评价二价有毒金属镉的化学分配行为和生物可获性或毒性的有效方法。酸解硫化物时同步提取的金融镉SEMCd^2 与AVS的摩尔浓度之比SEMCd^2 ]/AVS]可用作评价缺氧状况下镉沾污沉积物的环境质量和毒性的判据。

THE EFFECT OF ACID-VOLATILE SULFIDE ON GEO-CHEMISTRY CHARA CTERISTICS AND TOXICITY OF CADMIUM IN MARINE SEDIMENTS

In this study,the geochemical partitioning and che mi cal activity of toxic metal cadmium in a sediment-pore-water system,and the re l ationship between chemical activity and benthos toxicity of cadmium,were analyse d in the marine sediment containing sulfides. A series of spiking experiments fo r sediments,pore-water analyses and 10d amphipod sediment toxicity tests were c onducted in laboratory. We found that the toxicity of the sediment spiked with c admium is correlated with concentration of cadmium in pore-water,but it is not accociated with total cadmium added to the sediment. Partitioning of cadmium bet ween solid and aqueous phases in the sediment-pore-water system is controlled b y acid-volatile sulfide(AVS). AVS normalization of sediment cadmium concentrat i ons can be used as an effective method to predict and assess the chemical partit ioning behavior,bioavailability or toxicity of cadmium within sediments. The mol a r ratio of simultaneously extracted metal(SEM) cadmium to AVS,SEM Cd 2+] /,could be a useful indicator for asse ssing the benthic environmental quality and the toxicity of the anoxic sediment contaminated with cadmium.