闽浙沿岸海域沉积物中汞和甲基汞的含量分布及其影响因素

DISTRIBUTIONS OF MERCURY AND METHYLMERCURY IN SEDIMENTS OF MIN-ZHE COASTAL AREA AND INFLUENCING FACTORS

在2012年6月实施的国家自然科学基金春季航次中,采集了闽浙沿岸海域表层和岩心沉积物样品。对沉积物样品进行了汞和甲基汞的分析测试,并结合沉积物中常量元素含量、粒度组分、有机质含量和孔隙水中硫酸根离子浓度等系统地分析了汞和甲基汞含量的分布及其影响因素。研究结果表明：（1）闽浙沿岸海域沉积物中汞和甲基汞含量分布大致表现为近岸含量高（杭州湾以南浙江沿岸）,远岸含量低的特点。泥质区岩心沉积物中汞的甲基化作用主要发生在近表层较小的深度范围内（泥质区北部和南部,其深度范围分别为0~15和0~13cm）。（2）在闽浙近岸泥质区,汞的原位甲基化是甲基汞的主要来源,在成岩过程中,埋深或其他环境条件的变化可以导致甲基汞的转移或再分配。（3）影响沉积物中汞和甲基汞含量分布及甲基化作用强弱的因素主要包括人为污染、海流体系、粒级组成、有机质含量和硫酸盐还原菌活性。人为污染是沉积物中汞含量的主控因素;海流体系控制着汞含量的分布格局;粒级组成影响着甲基汞的富集程度;有机质对表层沉积物中汞的甲基化作用影响不明显,在岩心沉积物中,既可以促进汞的甲基化,也可以抑制汞的甲基化,主要取决于沉积物中有机质的类型;硫酸盐还原菌的活化能力是汞甲基化作用的主控因素之一。

Both surface and cores sediments were taken in the Min-Zhe coastal area in the spring cruise of National Natural Science Foundation of China in June,2012.Distributions of mercury and methylmercury（MeHg）contents and their influencing factors are systematically analyzed in combination with the contents of major element,grain-size and TOC of the sediments and the concentration of sulfate in pore-water.It is revealed that,（1）Mercury and MeHg are enriched in the sediments in the Min-Zhe coastal area（the alongshore area of the southern Hangzhou Bay,Zhejiang）.Methylations in cores in the mud area mainly observed in the shallow depth from surface（the depths are 0-15cm and 0-13cm respectively in north and south area）.（2）In Min-Zhe coastal mud area,MeHg mainly comes from in situ methylation.Any changes in depth or other environmental conditions may lead MeHg to transfer or relocate in diagenetic process.（3）Influencing factors of methylation and content distributions of mercury and MeHg in sediments include contaminant,circumfluence,grain-size,the content of TOC and the activity of sulfate-reducing bacteria.Contaminant primarily controls the content of mercury in the sediment.Circumfluence dominates the distribution of mercury content.Grain-size affects the degree of enrichment of MeHg.The effect of TOC content on methylation is not obvious in surface sediments of this study.In cores,the content of TOC can not only promote the methylation,but also inhibit it,mainly depending on the type of organic matters in sediments.The activity of sulfate-reducing bacteria is one of the main controlling factors of mercury methylation.