达里诺尔湖表层沉积物中Hg、As的形态分布及释放特性

以达里诺尔湖为研究对象,采用七步逐级连续化学提取法,系统开展了表层沉积物中Hg、As的形态分析研究,重点模拟了不同pH下表层沉积物中Hg、As的释放特性。结果表明,达里诺尔湖表层沉积物中Hg的生物有效态主导形态为腐植酸结合或络合态,As的生物有效态主导形态为碳酸盐与铁锰氧化物结合态。在实验pH范围内,碱性或弱碱性环境不利于Hg和As的释放,强碱性环境利于Hg和As的释放;经酸溶液浸提过的沉积物,因金属氧化物的溶解使腐植酸结合或络合态的Hg、As暴露并在碱提取液中释放;经碱溶液浸提过的沉积物,因腐植酸的溶解使铁锰氧化物结合态Hg、As暴露并在酸提取液中释放。保持达里诺尔湖水体偏碱性状态对湖泊的水环境健康和生态安全至关重要。

Fractions and Releases of Mercury and Arsenic in Sediments of Dalinuoer Lake, China

Fractions and releases of a heavy metal in sediments affect its environmental behaviors. In this work, a seven-step sequential extraction method was used to extract mercury(Hg) and arsenic(As) in the surface sediments from Dalinuoer Lake. Also, releasing of Hg and As from the sediments at different pH was examined. The results showed that Hg bioavailability in sediments was primarily fraction bound to humic acid, and that of As was carbonates and Fe-Mn oxides fractions. Releases of Hg and As from the sediments were little in alkali and weak alkaki solution, but significant in strong alkali solution. Pre-extraction by acid solution resulted in more Hg and As released in alkaline extraction because dissolution of the metal oxides exposed more metals bound to humic acid. Likewise, more Hg and As were extracted in acid solution after the sediments were pre-extracted with alkali solution, due to exposed Fe-Mn oxides from dissolution of the humic acid by alkali solution. Keeping lake water under weak alkaline conditions is the key to health and ecological safety in Dalinuoer Lake.