海南东寨港红树林湿地表层沉积物中汞的分布特征及富集因素分析

Distribution Characteristics and Enrichment Factor Analysis of Mercury in Surface Sediments of Mangrove Wetland in Dongzhaigang,Hainan

以海南东寨港红树林湿地为研究区,采集了36个表层沉积物样品,综合分析了沉积物中主微量元素含量、碳氮比(C/N)等地球化学指标,探讨了研究区表层沉积物中汞(Hg)含量的分布特征、来源以及环境因子对表层沉积物中汞富集的影响。结果表明:(1)研究区表层沉积物中Hg含量的平均值为0.33μg/g,表现出潟湖口门和东寨港东岸周围表层沉积物中Hg含量高、东寨港南岸表层沉积物中Hg含量低的特征;(2)表层沉积物的物源为火成岩,表层沉积物中Hg含量与物源的化学风化程度呈负相关关系,且随着Na、Ca的风化流失,Hg也从表层沉积物中迁移释放;(3)表层沉积物中Hg含量与C/N比值具有相关关系,说明内源有机质增强了微生物活性,不利于表层沉积物中Hg的富集;(4)表层沉积物中可迁移释放的Hg,部分以吸附态赋存于沉积物中,影响吸附态Hg迁移行为的主要因素为pH值。

Taking mangrove wetland of Dongzhaigang as the research area,this paper collects 36 surface sediment samples,and comprehensively analyzes the main trace element content,carbon nitrogen ratio(C/N)and other geochemical indexes.In addition,it also discusses the distribution characteristics,sources of Hg content in the surface sediments of the study area,and influence of environmental factors on mercury enrichment.The results are as follows:(1)The average Hg content in the surface sediment in the study area is 0.33μg/g,which shows the characteristics of high mercury content in surface sediments of the lagoon gate of Suoshi and the East Bank of Dongzhaigang,and low mercury content in surface sediments of the South Bank of Dongzhaigang;(2)The source of surface sediments is volcanic rock,in which Hg content is negatively related to the chemical weathering degree of the provenance.With the loss of Na and Ca weathering,Hg also migrates and releases from the sediments;(3)The content of Hg in surface sediment is related to C/N ratio,which indicates that endogenous organic matter enhances microbial activity and is not conducive to mercury enrichment in surface sediment;(4)The Hg released in the surface sediment is partly in the sediment with adsorption state,and the main factor affecting the migration behavior of Hg in the adsorbed state is pH value.