Assessing a Mercury Affected Area from Small-scale Gold Mining in Poboya, Central Sulawesi, Indonesia

Abstract

Poboya, Central Sulawesi is one of the primary sites used for small-scale gold mining activities in Indonesia. Poboya consumes 200-500 kg of mercury/day by amalgamation. Palu, the capital city of Central Sulawesi, is a city with a population of 0.35 million people and located around 11 km away from the edge of a small-scale gold mining area in Poboya. Fifteen samples of upper layer soil and fifteen samples of plant (Calotropis gigantean) were taken along the road that connects Poboya to Palu, at every 500 m. Mercury concentration in the soil samples showed a gradual decrement as the distance from Poboya became greater. The plant samples also revealed a similar trend to the soil samples. The highest concentration of mercury in the soil was found at Poboya—i.e. 17.62 ng/mg, and the concentration of mercury in Calotropis gigantean grown at Poboya was 6.5 ng/mg. Based on the soil samples and pollution index, the data showed that the research area had heavy pollution levels up to 4 km. Moreover, the transfer factor was in the range of 0.13-3.44 at distances of 0-4 km, respectively.