The distribution of mercury around the small-scale gold mining area along the Cikaniki river, Bogor, Indonesia

• The distribution of T-Hg concentration around the ASGM site was investigated.
• The Hg from the ASGM dispersed through the air and causes an increase in T-Hg at the soil surface.
• The soil surface showed the highest T-Hg and the value decreased with depth.
• A similar vertical distribution was observed between T-Hg and TOC.
• The slope of T-Hg vs. TOC plots may reflect a depositional rate of mercury.

The distribution of mercury in the soil, sediment and river water around the artisanal small-scale gold mining (ASGM) area along the Cikaniki River, West Java, Indonesia, was investigated. The total mercury concentration (T-Hg) in the forest soil ranged from 0.11 to 7.0 mg kg−1, and the highest value was observed at the ASGM village. In the vertical T-Hg profile around the villages, the highest value was observed at the soil surface, and the concentration decreased with depth. This result suggested that the mercury released by mining activity was dispersed through the atmosphere and deposited on the surface. The total organic carbon content (TOC) showed a similar vertical profile as the T-Hg, and a linear relationship was found between T-Hg and TOC. Mercury deposited on the surface can be absorbed by organic matter. The slope of the line was larger near the ASGM village, implying a higher rate of deposition of mercury. The T-Hg in the sediment ranged from 10 to 70 mg kg−1, decreasing gradually toward the lower reaches of the river. Mining waste can be transported with the river flow and deposited along the river. The distribution of the mining waste can be determined using the mineralogical composition measured by X-ray fluorescence spectrometry.