城市景观水体甲基汞的形成机制及微宇宙模拟研究

Microcosm Simulation Study and Methylmercury Forming Mechanism at Landscape Water of City

汞对环境的危害已经成为研究热点之一,尤其是水体底泥作为污染物的主要储蓄库,其对水质以及生物的影响研究非常重要.本文以合肥市景观水体为研究对象,调查分析底泥中无机汞和甲基汞的污染现状,并采用微宇宙试验模拟"底泥-水-草-鱼"生态系统中无机汞和甲基汞的转化过程及其甲基汞的富集机制.结果表明,合肥市景观水体10个底泥样品中无机汞和甲基汞含量范围分别在11.74~13.12μg·kg^(-1)和0.37~2.23μg·kg^(-1)之间.微宇宙模拟试验显示,随着培养时间增加,底泥中无机汞含量逐渐减小,甲基汞含量先增加后递减至平衡;水体中无机汞和甲基汞含量均呈递增趋势;水蕴草和草金鱼中无机汞的含量呈先增长后下降趋于平衡趋势,但总量较小,而水蕴草和草金鱼对甲基汞均具有较高的富集能力,其中,草金鱼(身)对甲基汞富集能力最强,其富集系数也最大.

Mercury is harmful to the environment,which has gradually become one of the research hotspots. Sediments,as a main repository of pollutants,have an important impact on water quality and the internal organisms,which deserves our research. In this paper,we focused on Hefei landscape water sediment and tried to investigate the status of inorganic mercury and methylmercury pollutions in the sediment. To study the conversion process from inorganic mercury to methylmercury and their enrichment levels and mechanism,we established the ecological chain of ＂sediment-water-grass-fish＂through analog microcosm examination. The results were as follows： from ten water and sediment samples in Hefei landscape water sediment,we found that the contents of inorganic mercury and methylmercury ranged 11. 74-13. 12 μg·kg^-1 and 0. 37-2. 23 μg·kg^-1,respectively. The microcosm examination showed that： with increasing culture time,inorganic mercury in sediments gradually decreased. There was a phenomenon that the content of methylmercury increased at first and then decreased to reach the balance later. Both the inorganic mercury and methylmercury in water change showed an increasing trend. The enrichment contents of inorganic mercury in Egeria densa Planch. and golden mandarin fish（ Siniperca scherzeri Steindachner） were low while their enrichment of methylmercury could be great. In addition,we found that both the bioaccumulation ability and the enrichment coefficient of methylmercury in the body of golden mandarin fish were the maximum during the same period.