SPATIAL AND TEMPORAL DISTRIBUTION OF METHYLMERCURY IN TWO NEW RESERVOIRS ON THE UPPER COURSE OF WU JIANG RIVER
YAO Heng1,2,FENG Xin-bin1,GUO Yan-na1,2,MENG Bo1,2(1.State Key Laboratory of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550002,China;2.Graduate School of Chinese Academy of Sciences,Beijing 100039,China)
In order to find out whether methylmercury concentrations will increase by building new reservoirs,this study concerns two new reservoirs(Hongjiadu and Suofengying Reservoirs) built in Wujiang River in Guizhou Province.Methylmercury concentrations of different seasons in the water columns about these two reservoirs were determined by distillation-ethylation GC-CVAFS technique,the minimum level has been established as 0.009 ng/L.Influences on the distribution of Methylmercury from water quality parameters and the characteristic of methylmercury in the water columns were discussed.The results were as follows:For Hongjiadu reservoir,in summer total methylmercury concentrations averaged 0.11 ng/L,in autumn averaged 0.08 ng/L,and in winter,averaged 0.10 ng/L;For Suofengying reservoir,in summer total methylmercury concentrations averaged 0.11 ng/L,averaged 0.07 ng/L in autumn,and averaged 0.09 ng/L in winter.The results showed that methylmercury concentrations were relatively low in the water columns,and below the limits for Chinese environmental quality standards.Methylmercury levels were comparable to data reported in other uncontaminated reservoirs.It indicated that methylmercury concentrations in the water were no change with depth.In summer the methylmercury concentrations were higher than in autumn and winter,as a result of higher temperature and more rainfall.At the same time,low methylmercury levels may be due to a low concentration of organic matter in submerged soil and other environmental factors(eg.higher pH concentrations and lower DOC concentrations).Lower mercury methylation was expected in these two reservoirs.With the development of reservoir,it is possible that the methylmercury concentrations will increase due to autochthonous and extraneous organic materials,and methylmercury may be released due to thermal stratification.But this was not confirmed.
【CateGory Index】： X832
【CateGory Index】： X832