陡河水库鱼体汞的生物积累初探

Preliminary Study on Bioaccumulation of Mercury in Fish from Douhe Reservoir

为了解陡河燃煤电厂大气汞释放对毗邻的陡河水库水生生态系统中鱼体汞含量、生物积累和放大等的影响,本研究采集陡河水库野生鱼、虾和螺蛳,分别测定了鱼样等生物样品中的总汞和甲基汞,并对部分代表性样品测定稳定碳氮同位素比值。鱼汞分布特征和δ13C‰和δ15N‰同位素比值分布特征显示:鱼体(鲜样)中总汞和甲基汞平均含量分别为56.4±26.7和15.5±8.4 ng·g-1,总汞含量最高的是杂食性的白条鱼为133 ng·g-1。不同食性的鱼体δ13C和δ15N稳定同位素值变化范围分别为-28.1‰^-24.4‰和12.0‰~16.1‰,Log10[Hg]与δ15N的线性相关斜率值为负值。以上结果表明:陡河水库鱼体汞总体偏低,没有发现高生物积累和生物放大,其主要原因在于陡河水库水环境中汞含量较低,且陡河水库靠近市区,过度捕捞使可以捕获的鱼样种类和数量偏少,且鱼龄较低。

To understand the impact of atmospheric mercury emissions from a coal-fired power plant on the distributions of mercury in fish as well as bioaccumulation and biomagnification processes of mercury in the food chain,wild fish,shrimp and snails were collected from Douhe reservoir close to the Douhe coal-fired power plant.Total mercury （THg） and methylmercury（MeHg） concentrations for all these samples were measured and some of them were selected for measurements of stable carbon and nitrogen isotopes.Our results showed mean concentrations of 56.4 ±26.7 ng·g-1for THg and 15.5 ±8.4 ng·g-1for MeHg in wet weight.The highest THg concentration of 133 ng·g-1 is observed in omnivorous fish （Hemiculterleuciculis）.δ13C and δ15Nvalues for fishes with different feeding habits were in the ranges of from-28.1‰ to-24.4‰ and from 12.0‰ to 16.1‰,respectively.A correlation with a negative slope was observedbetween lognormal concentrations of THg （Log10[Hg]） and δ15N.Our results indicate that THg and MeHgin fish in Douhe reservoir were at a relatively low level,and no strong bioaccumulation and biomagnifications was found.The explanations may include low mercury concentrations in water,limited species and populations of fish due to the overfishing,and short ages of fish.