贵州高原水库汞的分布特征及其对富营养化的响应

于2012年11~12月采集贵州不同营养状况的6座水库——三板溪水库、龙滩水库、万峰湖水库、百花湖水库、红枫湖水库和阿哈水库水样,分析水体中汞的形态分布及与水体富营养化之间的关系,探讨水体汞形态及其分布特征对水体富营养化的响应.结果表明:6座水库总汞浓度的平均值为(5.82±4.99)ng/L,其中在阿哈水库的库中和百花湖水库的岩脚寨采样点存在不同于其它点的局部污染源;MeHg浓度平均值为(0.08±0.07)ng/L,阿哈水库的MeHg浓度较高是其它水库的2~10倍,约为0.26ng/L.在枯水期,贵州6座水库的富营养化程度不同,其中三板溪水库和龙滩水库为表现为贫营养型;万峰湖水库表现为为贫中营养型;百花湖水库和红枫湖水库表现为为中富营养型;阿哈水库为富营养型.富营养化指数与总汞、甲基汞和溶解态甲基汞皆呈显著正相关(r=0.477,P<0.05; r=0.558, P<0.05;r =0.502, P< 0.05, n=19).富营养化对水库生态系统中形态汞之间的迁移和转化有着重要影响,为溶解态汞和甲基汞的生成提供了有利条件,对水体中汞的地球化学循环的影响不可忽视.

Distribution of mercury and its response to eutrophication in reservoirs in Guizhou Province

In order to understand the distribution of mercury and its response to eutrophication in reservoirs in Guizhou Province, six reservoirs including Sanbanxi, Longtan, Wanfeng, Baihua, Hongfeng, and Aha Reservoirs, were chosen in this study. Surface water samples were collected during the period from November to December in 2012.Trophic status, morphology, and species of Hg level in each sample were determined. Our results showed that, the six reservoirs presented different trophic status, with oligotrophic for the Sanbanxi and the Longtan, oligo-mesotrophic for the Wanfeng, mid-eutrophic for the Baihua and Hongfeng, eutrophic for the Aha Reservoir, respectively. The average total Hg concentration in surface water samples was (5.82±4.99)ng/L the corresponding MeHg concentrations was (0.080±0.068) ng/L. the mean concentration of MeHg in surface water samples in Aha Reservoir was 0.258ng/L, which was approximately 2~10times higher than those in the other five reservoirs. TLI in surface water samples was positively correlated with THg (r=0.477,P<0.05,n=19), MeHg (r=0.558,P<0.05,n=19), and DMeHg (r=0.502,P<0.05,n=19), respectively. The eutrophication is probably one of the key factors which controls the geochemical cycle of Hg in waterbody in the selected six reservoirs. The deterioration of water quality (i.e. hypoxia, decreasing pH, etc.) and overgrowth of phytoplankton resulted from Eutrophication influenced the distribution and transformation of species of mercury in the ecological system of reservoir.