| 其他摘要 | Some studies have revealed that reservoir is one of the typical Hg-sensitive ecosystems in northern Europe and North America, and sepecial attention has been paid to methylmercury pollution in fishes in newly constructed reservoirs. In this thesis, we present a comprehensively study on the distribution and transformation of mercury species the Dongfeng reservoir. In August 2007, December 2007, and April 2008, samples from water columns, sediment profiles, and inflow and outflow streams of Dongfeng reservoir were collected and analyzed to study the influence of man-made reservoir on the environmental biogeochemistry of Hg. some main conclusions were obtained as follows:
1. Discernible seasonal change of different mercury in water body were obtained in
Dongfeng Reservoir. The concentrations of total mercury(THg) were 1.1-2.3ng/L, the average is 1.6ng/L ; The concentrations of dissolved (DHg) ranged from 0.3-1.3ng/L, the average is 0.6ng/L ;The concentrations of particulate mercury (PHg) were 0.3-1.5 ng/L, the average is 0.8ng/L; The concentrations of reactive mercury (RHg) were 0.2-0.6ng/L , the average is 0.4ng/L; The concentrations of methylmercury(TMHg) were 0.04-1.01ng/L , the average is 0.27ng/L; The concentrations of dissoved methylmercury (DMHg) were 0.03-0.48ng/L , the average is 0.12ng/L; The concentrations of particulate methylmercury (PMHg) were 0.01- 0.7ng/L , the average is 0.16ng/L.
2. With regards to the whole sampling periods, the concentrations of HgP in Dongfeng
Reservoir water body were evidently correlated to the concentrations of total mercury, it shows that total mercury was mostly associated with particles mercury.
The concentrations of methylmercury in water body were also evidently correlated
to the concentrations of dissolved mercury. The dissolved mercury evidently effects the distribution and transportation of methylmercury. However, there is no correlated between methylmercury and total mercury.
3. The dissolved mercury, reactive mercury, dissolved methylmercury levels in the water body in summer were much higher than those in winter and spring .The distribution, speciation and levels of mercury in Dongfeng Reservoir water body were governed by several factors, such as the output of river, the release ofsediment .
4. Discernible seasonal change of total mercury and methylmercury in porewater were obtained during the sampling periods, with the concentrations in summer were generally higher than those in winter and sping. The methylmercury in pore water column were correlated to organic materials in the sediment (r=0.219＊,n=133). Maximum levels of methylmercury in sediment profiles changed greatly, with no distinct concentration grads.
5. Total mercury levels in the whole sediments in Dongfeng Reservoir were 97-354ng/g , the average is 180ng/g, without significant variations between different seasons. The total mercury levels in Dongfeng Reservoir were higher compared to data reported in other uncontaminated reservoirs. The levels of methylmercury were 0.1-5.5ng/g, the average is 2.1ng/g.
6. The concentrations of HgD and MeHgD in porewater were higher than that obtained in the underlying water, with a great concentration grads, which suggested that the sediment was a dominant Hg source to the reservoir. |
修改评论