Environmental contamination and chemical speciation of arsenic in the water system from some abandoned Au-Ag mines, Korea

Abstract
Mine waters, surface waters and groundwaters were sampled in and around five Au-Ag mine areas (Dongil, Okdong, Dongjung, Gubong and Samkwang mine). The main contamination sources of As in these abandoned Au-Ag mines can be suggested by mine tailings and waste materials including the sulfide gangue minerals (arsenopyrite). The pollution levels of As in mine water ofthe Dongit (524  g/L) and the Samkwang mine (444  g/L) were much higher than those of the Okdong (17  g/L) and the Gubong mine (56  g/L). Elevated levels of As in stream water were also found in the Dongil (0.9~118  g/L) and the Samkwang (21~1042  g/L) mine. Arsenic concentration in groundwater was highly elevated in the Dongil (0.9~64  g/L), the Okdong (0.2~69  g/L) and the Gubong (0.5~101  g/L) mine areas. Arsenate (H ₂AsO ₄^-) was more dominant than arsenite (H ₃AsO ₃) in waters from the most mine areas. However, the concentration ratio of As(III) to As (total) present up to 75% in stream water from the Okdong mine and 62% in groundwater of the Okdong mine compared with other mine areas.