贵州高原水库冬季浮游植物中汞及甲基汞分布特征

Distribution characteristics of mercury and methylmercury in phytoplankton at Guizhou Plateau reservoirs in winter

为了解贵州高原水库浮游植物中汞和甲基汞的分布特征及浮游植物对汞及甲基汞的富集特点,于2012年12月对贵州省的5座高原水库中浮游植物和汞形态进行采样调查.研究结果表明：冬季贵州高原水库浮游植物群落主要是由硅藻组成,5座水库浮游植物丰度有明显差异.百花湖大坝处浮游植物丰度最高,为29.05×104cells/L;三板溪水库浮游植物丰度最低,仅为0.49×104cells/L.浮游植物中总汞和甲基汞的浓度分别在29.29~277.07 ng/g和1.12~10.93 ng/g之间,总汞含量以百花湖岩脚寨最高,甲基汞含量以百花湖大坝最高.总汞和甲基汞在浮游植物中的生物富集系数分别在1.42×104~9.78×104和3.10×104~4.43×105之间.在浮游植物富集无机汞及甲基汞的系数中,百花湖中浮游植物对无机汞生物富集系数最高,而红枫湖中浮游植物对甲基汞的生物富集系数最高.浮游植物种类组成不同对汞及甲基汞的生物富集有影响.浮游植物中的总汞与水体中的总汞、甲基汞和溶解态甲基汞都存在显著的相关关系,浮游植物中的甲基汞与水体中的总汞及甲基汞不存在显著相关性.甲基汞在浮游植物中富集不是简单的吸收,存在着影响甲基汞在浮游植物中富集的其它因素.浮游植物中的甲基汞与水体富营养化环境因子（透明度、总氮、硝氮）均呈负相关关系,表明水体富营养化的程度不同对浮游植物中的甲基汞浓度有影响.

To understand the distribution characteristic and bioaccumulation factors（BAF） of total mercury（THg） and methylmercury（MeHg） in phytoplankton at Guizhou Plateau reservoirs,southwest of China.The phytoplankton and water samples were investigated at five reservoirs in the winter of 2012.The results showed that diatom was the dominant algae at Guizhou Plateau reservoirs in winter and phytoplankton abundance had obvious difference at the five reservoirs.The maximum phytoplankton abundance was about 29.05 × 104cells / L at Lake Baihua dam,and the minimum only 0.49 × 104cells / L at Sanbanxi Reservoir.The concentrations of THg and MeHg in phytoplankton were 29.29-277.07 ng / g（dry） and 1.12-10.93 ng / g（dry）,respectively.The maximum concentrations of THg and MeHg in phytoplankton was at Lake Baihua.The BAF of THg and MeHg in phytoplankton were 1.42 × 104-9.78 × 104and 3.10 × 104-4.43 × 105,respectively.The maximum BAF in phytoplankton of THg was at Lake Baihua.The maximum BAF of MeHg in phytoplankton was at Lake Hongfeng.There was different effect on biological enrichment of mercury and methylmercury for different phytoplankton species composition.There were significant positive correlations between MeHg in phytoplankton and THg,MeHg,dissolved MeHg（DMeHg） in water.No significant correlation was found between MeHg in phytoplankton and the THg,DMeHg in water.MeHg was not only absorbed by phytoplankton.There were other factors influencing MeHg concentration in phytoplankton inevitably.There were significant negative correlations between MeHg in phytoplankton and environmental factors（SD,TN,NO-3-N）.The degree of eutrophication had effects on MeHg concentration in phytoplankton.