贵州百花湖鱼体汞污染现状

Present situation of fish mercury pollution in heavily mercury-contaminated Baihua reservoir in Guizhou

以西南汞污染严重的贵州百花湖为对象，选取湖中优势鱼、贝类，通过测定其总汞和甲基汞含量，并结合水体、沉积物汞含量和相关水质参数，探讨了百花湖鱼类汞污染的现状及其影响因素。百花湖鱼体总汞平均含量为28．0ng·g-1，变化范围为4．2～143ng·g-1；甲基汞的平均含量为10．9ng·g-1，变化范围为3．0～39．3ng·g-1。虽然百花湖遭受上游贵州有机化工厂含汞废水的严重污染，但鱼体汞含量并没有超过国家食品卫生标准。其主要原因可能是：百花湖的鱼主要是人工养殖的草食性或杂食性鱼类，鱼龄较小，且其摄取的食物汞含量低、食物链简单，不利于汞的富集；其次，其较快的生长速度对鱼体汞具有生物稀释的作用。

Based on the determinations of total mercury （THg） and methyl mercury （MeHg） in the predominant fish and shellfish in the Baihua reservoir in Guizhou, a typical Hg-contaminated reservoir in Southwest China, and combined with the observation data about the Hg concentra- tions in water body and sediment and related parameters of water quality, this paper evaluated the present situation of fish Hg pollution and its affecting factors in the reservoir. The results showed the average concentration of THg and MeHg in the fish was 28. 0 ng·g-1 （ ranging from 4. 2 to 143 ng ·g-1 ） and 10. 9 ng ·g-1（ranging from 3.0 to 39. 3 ng ·g-1）, respectively. Though the reservoir was seriously polluted by the Hg-containing wastewater discharged from Guizhou Organic Chemical Plant, the THg and MeHg concentrations in the fish did not exceed the China＇ s nation- al guidance limit for Hg in fish, possibly due to ： 1 ） most of the fish （ mainly herbivorous or om- nivorous fish） were cultivated and young, and their food chains were simple and low Hg-containing, being not beneficial to the bioaccumulation of Hg in fish, and 2） the faster growth rate of fish bio-diluted the Hg level in fish.