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Increasing large-scale and rampant small-scale mining activity in Mongolia is raising fears about the possibility of regional environmental pollution. To characterise the level of groundwater pollution related to large- and small-scale underground resource development in the Mongolian plateau, we analysed 10 groundwater and 3 surface water samples collected from three areas: the Oyu Tolgoi mining area (n = 3), the Tavan Tolgoi mining area (n = 9) and an abandoned small-scale gold-mining site in the suburban of Ulaanbaatar (n = 1). The samples were collected between 29 August and 5 September 2012. Measurement parameters included pH; electrical conductivity; dissolved organic carbon; dissolved nitrogen; and the concentrations of major ions and trace elements. Principal component analyses, Piper diagrams and enrichment factor analyses were applied to a set of hydrochemical data. Water samples were analysed to identify components that may adversely affect the regional environment and human health. Analytical measurements showed that the studied sites were highly affected by fossil salt water and trace elements derived from anthropogenic activity. We found that groundwater samples from the Oyu Tolgoi area were more polluted than those from the Tavan Tolgoi area. Because wells in the pasture area adjacent to the mining sites supply drinking water for livestock and nomads, it is especially important to monitor these wells for NO3−, As and Se, for which the World Health Organisation has established drinking-water guidelines. The concentrations of NO3−, As and Se in wells may be used as indicators to evaluate the human and livestock health risks related to mining activity in this area.

To clarify the regional difference in mercury pollution the Lake Biwa watershed in central Japan, we monitored the mercury concentration in rainwater at four sites in the Lake Biwa watershed in Shiga prefecture. These observation sites were as follows Surumi as the northern site, Kutsuki as the western site, Aburahi as the southern site and Hikone as the eastern site. The total mercury average concentrations in Surumi, Kutsuki, Aburahi, and Hikone were 6.67±1.74 ng • L , 5.98±1.66 ng • L , 8.76±3.29 ng • L , and 7.45±2.08 ng • L , respectively. We estimated the annual mercury deposition in 2012 in Surumi, Kutsuki, Aburahi, and Hikone, and found into range from 10.4 to 17.5 μg • m . The Lake Biwa watershed is wide to the north and south, and the environmental conditions are different between sites. The mercury deposition markedly fl uctuates throughout the north and south of the Lake Biwa watershed. Therefore, it is necessary to evaluate the direct mercury load to Lake Biwa through rainwater at many sites.