东海沉积物汞形态分布及控制因素

Distribution of Mercury Species and Their Controlling Factors in the Sediment of the East China Sea

为研究东海近海沉积物中不同形态汞的分布特征及关键控制因素,分别于2014年秋季和2015年夏季采集了东海近海表层沉积物样品,测定了总汞和甲基汞浓度。结果表明,东海沉积物总汞整体呈现由近岸向远海递减的趋势,表明其受陆源输入影响较大;甲基汞分布趋势相反,外海高于近岸,说明原位生成相对陆源输入作用更大。与其它海洋环境相比,东海沉积物中甲基汞浓度较高;总汞浓度高于开放海区,与其他海湾和近海体系相比处于中间水平。汞富集因子(EF)计算结果表明东海沉积物汞污染总体处于轻度至中度污染水平。沉积速率估算结果表明,与其他海洋体系相比,东海总汞和甲基汞沉积较快。同时测定了沉积物烧失量(LOI)、含水率、Fe、Mn等环境参数,通过Spearman相关分析与多元线性回归分析探究了影响东海总汞和甲基汞分布的主要因素,结果表明:有机质含量和微生物群落等环境因素可能是影响沉积物中甲基汞浓度的关键因素,而人为输入和铁含量是影响沉积物中总汞浓度的关键因素。

Sediment samples were collected in autumn 2014 and summer 2015 in the East China Sea(ECS)to investigate the distribution of mercury species and theirmajor controlling factors in this marine system.The results showed thattotal mercury(THg)generallypresented a decreasing trend from the nearshore to offshore,suggesting the importance ofterrestrial discharge in controlling THg in ECS sediment.A contrary distribution trend was observed for methylmercury(MeHg)in ECS sediment,indicating that in situ methylation may play a more important role in controlling MeHg levels.MeHgconcentrations in ECS sediment were higher than that in most marine systems,while THg in ECS sediment was higher than those in most open seas andcomparable to those in the bays andcoastalseas.The results of enrichment factors(EF)suggest that ECS sediment is minorly or moderately polluted by mercury.Compared to other marine systems,higher sedimentaccumulation of THg and MeHg was observed in the ECS.Loss of ignition(LOI),moisture content,Fe and Mn contents in ECS sediment were also measured to identify the major factors controlling THg and MeHg in ECS sediment.The results of Spearman correlation and multiplelinear regression analyses suggest thatLOI and the microorganisms in the sediment may be the major factors controlling MeHg in thesediment,while anthropogenic dischargeand total iron were identified to be the main controlling factor for THg.