东寨港海水及沉积物中Hg和As形态分布研究

Speciation Characteristics of Mercury and Arsenic in Seawater and Sediments from Dongzhai Harbor

文章调查了东寨港红树林湿地近岸海水及潮间带表层沉积物汞（Hg）和砷（As）化学形态组成及分布。采用改进BCR逐级提取法分析沉积物中2种元素的化学形态。结果表明,海水中Hg和As主要以溶解态存在,夏季2种元素悬浮颗粒态的比例明显高于冬季,海水中ρ（Hg）明显超过国家一类海水水质标准,且夏季污染水平高于冬季。潮间带沉积物中w（Hg）为0.141-0.331 mg/kg,w（As）为10.226-27.020 mg/kg,采样点S6沉积物中w（Hg）和w（As）较其他采样点高,表现出受陆源输入影响;沉积物中Hg和As的化学形态组成存在差异,Hg主要以残渣态和酸可提取态存在,酸可提取态Hg的比例为21.0%-47.6%,存在一定的潜在环境风险。As主要以残渣态存在,环境风险相对较小。

Chemical speciation and distribution of mercury and arsenic in coastal seawater and intertidal sediments from Dongzhai Harbor were investigated. The chemical speciation of two elements in sediments was studied based on the BCR fractionation. The results showed that Hg and As in seawater were mainly presented as dissolved forms,the particulate proportion of 2 elements in summer was significantly higher than in winter. ρ（Hg） in seawater exceeded the first category of seawater quality standard and showed a relatively higher pollution levels in summer. w（Hg） and w（As） in sediments were ranged from 0.141~0.331 and 10.226~27.020 mg/kg respectively,which at sample point S6 higher than others showed an influence from terrestrial input. The speciation between Hg and As in sediments were different. Hg was mainly presented as acid extractable and residual forms,and the acid extractable fraction was ranged from 21.0% to 47.6% and posed potential environment risks. As was mainly presented as residual forms and posed lower environmental risk.