안정동위원소를 이용한 광산폐석장내 침출수 발생의 지화학적 특성 분석

초록

To characterize the waste rock pile of the Dongwon-wooseong coal mine located at Sabuk, Jeongseon-gun, Gangwon-do, Korea, samples of rain water, seepages and drill hole waters were collected and stable isotope compositions(δ18O, δD and δ34S) and some physicochemical properties(pH, temperature, Fe, Al, Mn and SO42- concentration) were analyzed. Physicochemical properties of waste rock pile seepage waters exhibited the oxidation of sulfide minerals (e.g. pyrite). When δ18O and δD of drill hole waters and seepage waters were compared to the local meteoric water line, the almost identical slope did not indicate any apparent evaporation process in the waste rock pile. To investigate the activity of sulfur oxidizing bacteria(SOB) in the waste rock pile, sulfur isotope ratios of seepage waters were analyzed. Even though, higher δ34S values(7.3～7.8‰) of seepage waters than that of rain water all year long do not support the activity of SOB, cultivation of SOB using 9K medium positively show the existence of SOB. To evaluate the source of oxygen in sulfate ion, δ18O compositions of drill hole waters, seepage waters and sulfate ions of these waters were analyzed. Theoretical calculation indicated that oxygen of sulfate ion mostly came from the oxygen of precipitation(average about 75%) and drill hole waters of No. 3 and 4 located near to the open slope of waste rock pile revealed that they were more affected by atmospheric oxygen(about 38% in average) than others were.

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