| Mercury is one of the most toxic heavy metals in the environment, and its negative impact on human and animal health aroused worldwide concern after the Minamata Disease occurred in Japan during the early 1950s. Since then, a series of studies on mercury contamination have been conducted both at home and abroad. Consequently, many important discoveries related to mercury pollution, such as the accumulation, transfer of mercury in aquatic ecosystem together with its potential damages to the food chain, were achieved. Moreover, The International Conference of Mercury As a Global Pollutant, which has been held six times successively since 1990, stimulated a new round of researches on mercury pollution. Issues like mercury ore exploitation, small-scale ore smelting works, global anthropogenic emissions of mercury and the biogeochemical cycle of mercury were thoroughly investigated.Anthropogenic activities contribute 50~70% of global mercury emission. Asian countries are the major releasers of mercury, which contributed approximately 50% of the total emission of all forms of mercury to atmosphere. In China alone, emission from power plants and small-scale industrial and commercial furnaces contributed more than 25% to the total global emission of this contamination. Besides coal burning, mining and smelting are also important source of anthropogenic input of mercury. In the past, researches in this domain mostly focused on the pollution caused by smelting and exploitation of mercury ore. Actually as an intrinsic element, mercury may also be released from the smelting process of non-ferrous metals such as lead and zinc. However, few researches have been undertaken concerning environmental pollution caused by mercury released in primitive zinc smelting workshop in the world.Hezhang County, located in China's southwestern Guizhou Province, is famous for its rich resources of lead and zinc mineral. A nearby stream called LiuChong runs downriver to join Wujiang River, which is a branch of the Changjiang. Primitive zinc smelting workshops have exited here for more than one hundred years. However, it was not until the past three decades that large-scale smelting works came into being. In this study, we chose the largest primitive zinc-smelting workshop as the target. By calculating the mercury concentration in ore, scoria, coal and slag, we could estimate the emission amount of mercury in the smelting process. Also we could investigate the impact of mercury emission on local water quality by comparing the mercury concentration in upriver spring, stream and river. Moreover, the influence of mercury on soil and crops could be obtained through the analysis of soil and crop samples from both contaminated area and the background zone. The results are expected to provide reliable theory for mercury pollution controlling in this region.The average concentration of mercury and zinc in sulfide minerals v/ere 66.83 (35.42-156.99) mg/kg and 45.24g/kg respectively, while the mean concentrations of mercury and zinc in oxide mineral were 13.41 (0.75-68.890) mg/kg and 20.12g/kg respectively. In coal and slag, the average concentrations of mercury were 0.33 (0.14-1.10) mg/kg and 0.16 (0.095-0.34) mg/kg respectively. In the process of zinc smelting, the mercury emission factor of sulfide mineral and oxide mineral was 147.37 gram mercury per ton zinc and 65.85 gram mercury per ton zinc respectively. On the other hand, coal burning during smelting also released large amount of mercury, and its mercury emission factor was 2.01gram mercury per ton zinc (if the ore was oxide mineral) and 0.73 gram mercury per ton zinc (using sulfide mineral) respectively. By comparing the mercury emission factor of minerals with that of coal burning, mercury released from minerals were identified as themajor source. The linear correlation coefficient between concentrations of Hg and Zn, Pb, Cd was 0.83, 0.8, and 0.65(n=19) respectively, which all showed highly-significant positive correlation.The total mercury concentration in spring water (backgroun...
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