ENVIRONMENTAL IMPACTS OF MERCURY ON SOILS AND WATER RESOURCES IN SEKOTONG'S GOLD MINING VILLAGE IN LOMBOK ISLAND, INDONESIA

Abstract

The update levels of mercury concentrations and other physicochemical properties in soil and water resources (shallow groundwater and river water) during rainy season in December 2014 were measured for two Sekotong’s gold mining villages in Lombok, Indonesia, named Tembowong (TE) and Gawah Pudak (GP) villages. The data revealed gold extracting processes involved at residential areas burden soil, groundwater, and river water with mercury. Mercury concentrations (mean ± SE) in groundwater at TE village (n=7) and GP village (n=7) were 0.081 ± 0.017 ug/L and 0.407 ± 0.328 ug/L, respectively. In average (± SE), mercury concentrations in soils (n=7) were found at 0.392 ± 0.170 mg/kg in GP village and at 0.265 ± 0.160 mg/kg in TE village. Active cyanidation (n=1) contributed mercury concentration on soils (0.522 mg/kg) and groundwater (0.170 ug/L) which is higher than amalgamation which was found in soils and groundwater at site with amalgamation facility (n=8) were found respectively at 0.139 ± 0.075 mg/kg and 0.064 ± 0.009 ug/L. At sites with a combination of active amalgamation and cyanidation, mercury concentrations (n=1) increased on the 1.175 mg/kg on soils and 1.268 ug/L in groundwater. The groundwater in GP and TE village contained high % saline (mean ± SE) 1.09 ± 0.43. The mean level (± SE) of groundwater dissolved oxygen (DO) at the villages was 1.72 ± 0.35 mg/L. The result shows the groundwater oxidation-reduction potential (ORP) was less than 650 mV. Soils in both villages (pH, 6.40–9.19) were more alkaline than the groundwater (pH, 5.80–8.00). The soils in GP village were found more alkaline, humidity, salinity, ORP, and had higher mercury than found in TE village; however there was a significant difference only in the ORP (p < 0.01). At residences which also used as agricultural field (n=6), the mean level (± SE) of mercury was measured at 0.447 ± 0.385 ug/L in groundwater and at 0.455 ± 0.198 mg/kg in soils. Soil moisturizer was the only parameter associated positively to mercury concentrations of soils (rs=0.798). Besides, mercury concentrations (n=1) at the estuary zone were 1.764 ug/L, above the standard by US.EPA (< 1 ppb).