湛江湾沉积物中酸可挥发性硫和重金属含量分布及重金属生态风险评价

Distribution of acid-volatile sulfide(AVS) and heavy metal contents in sediment of Zhanjiang Bay and ecological risk assessment of heavy metals

测定了湛江湾海域20个站位表层沉积物中的酸可挥发性硫(AVS)、同步浸提重金属(SEM)、TOC含量和Eh值,对AVS、SEM含量的平面分布及AVS与SEM、TOC含量、Eh值的相互关系进行了分析.结果表明:该海域表层沉积物中AVS含量范围为0.004～0.547μmol/g,平均值为0.155μmol/g,SEM含量范围为2.10～4.27μmol/g,平均值为3.32μmol/g,相对其他海域湛江湾海域沉积物表现出AVS含量较低,SEM含量较高的特征.AVS与SEM含量平面分布较一致,湾顶的含量都较高,含量均值分别为0.361和3.52μmol/g,特呈岛以南到湾口呈逐渐减小的明显趋势.调查海域沉积物AVS与TOC含量呈显著正相关,与Eh值呈显著负相关,说明高有机质含量、低氧化还原电位沉积环境有利于AVS的生成.20个站位CSEM5-CAVS的差值均为0<(CSEM5-CAVS)<5,说明该海域可能存在重金属的中等毒性生态风险.

The acid volatile sulfides（AVS）,heavy metals（SEM）,total organic carbon（TOC） and Eh were investigated simultaneously in 20 surface sediment samples collected from Zhanjiang Bay,the plane distribution of AVS and SEM content as well as the relationships among AVS,SEM,TOC and Eh were analyzed.The results indicated that AVS content in the surface sediment ranged from 0.004 to 0.547 μmol/g with the mean of 0.155 μmol/g,SEM cotent in the surface sediment ranged from 2.10 to 4.27 μmol/g with the mean of 3.32 μmol/g,which revealed a feature of low AVS and high SEM in Zhanjiang Bay relative to other sea area.AVS and SEM distributed quite similarly,showing high content at the bay top with the mean of 0.361 μmol/g and 3.52 μmol/g,respectively,and they decreased gradually from the south of Techen Island to bay mouth.AVS were positively related to TOC and negatively to Eh,which suggested that the sediment environment with high organic substance content and low oxidation-reduction potential was propitious to AVS production.The differences of CSEM5-CAVS at 20 sample stations were 0（CSEM5-CAVS）5,which suggested that there was a moderate ecological risk of heavy metals in Zhanjiang Bay.