Qiu Guangle

The concentrations and distribution of mercury in aquatic ecosystem of Baihua Reservoir

Mercury species in water column, sediment and fish from the Hg-contaminated Baihua Reservoir were measured by trap pre-concentration and CVAFS and CVAAS detection methods. The results showed that the highest average total Hg concentration is up to 73.36 ng/L in the water column, 186.7 ng/L in pore water of surface sediment in the Baihua Reservoir. The total mercury concentrations in the sediments range from 0.87 to 33.74 mg/kg. This suggests that sediment re-suspending and Hg input from the upstream organochemical plant are the main mercury sources of water body for this reservoir. In addition, the possible reason why mercury is low in fish is that the low DOC and high pH are infavarable to methylmercury formation or absorption by fish.Mercury species in water column, sediment and fish from the Hg-contaminated Baihua Reservoir were measured by trap pre-concentration and CVAFS and CVAAS detection methods. The results showed that the highest average total Hg concentration is up to 73.36 ng/L in the water column, 186.7 ng/L in pore water of surface sediment in the Baihua Reservoir. The total mercury concentrations in the sediments range from 0.87 to 33.74 mg/kg. This suggests that sediment re-suspending and Hg input from the upstream organochemical plant are the main mercury sources of water body for this reservoir. In addition, the possible reason why mercury is low in fish is that the low DOC and high pH are infavarable to methylmercury formation or absorption by fish.

Buildup of methyl mercury in a seasonal anoxic reservoir and impact on downstream

In the present study, spatial and temporal distribution of methyl mercury in Hongfeng reservoir were investigated by distillation followed by aqueous phase ethylation, precollection on a Tenax, isothermal gas chromatog-raphy and cold vapor atomic fluorescence detection. Total methyl mercury (TMeHg) concentrations have no discernible difference (0.05 to0.33ng/L) in spring, autumn and winter. In spring, the methyl mercury in the inflows was important source of methyl mercury in reservoir. In summer, methyl mercury concentration increased significantly, and the highest value was up to0.923ng/L in the hypolimnion. The spatial distribution in summer suggested methylation in the water column and sedimentation of particle were responsible for the evaluated methyl mercury other than the release of sediment. There was a discernible negative relationship between methyl mercury and dissolved oxygen ( r = -0.81, n = 78). In spring, autumn and winter, the proportion of dissolved methyl mercury ( DMeHg) was lower than that of particulate methyl mercury, but most of methyl mercury was dissolved in hypolimnion in summer. The outflow of reservoir was rich in methyl mercury in summer, and the value was 5. 5 times higher than that in the infows. MeHg-enriched water from anoxic hypolimnia in reservoir also was discharged and potentially transported downstream where it could affect the ecosystem below the reservoir.

Distribution of Different Species of Mercury in Baihua Lake, Guizhou Province

Forty--four surface water samples were collected in Baihua Lake, Guizhou Province. The different species of mercury and water quality parameters, such as reactive mercury, dissolved mercury, particulate mercury, were tested. The spatial variability of different species of mercury in the surface water of Baihua Lake were studied based on the mathematical statistics and Geostatistics methods (Kriging). On the basis of the models of semivariance fitness, we used ArcGIS software to proceed Kriging interpolator to reveal the distribution patterns of different species of mercury in the surface water of Baihua Lake. The results indicate that mercury contamination in the surface water of Baihua Lake is due to headwaters, then mercury contents will decrease with the direction of flowing water. But in the region of eutrophication, the contents of particulate mercury and total mercury increase.