Abstract
Bone River, which is located in the eastern part of Gorontalo, Indonesia, has an issue of contamination by heavy metals due to artisanal small-scale gold mine (ASGM) activities. This river is used as a source of water by inhabitants living along the river, due to the lack of another clean water supply. The purpose of this study is to investigate the concentration of As from the mining site alongside Bone River, and to reveal the As pollution source. Water and sediment samples were collected from ASGM and along Bone River to the delta. The concentrations of As, Hg, and Pb in water samples were identified by inductively coupled plasma mass spectroscopy (ICP–MS), while concentrations in sediment samples were determined by particle-induced X-ray emission (PIXE). Results showed that the concentrations of As, Hg, and Pb in water ranged from 66 to 82,500 µg/L, 17 to 2080 µg/L, and 11 to 1670 µg/L, respectively. These levels exceeded, by 1000 to 10,000 times, the safe limits of drinking water defined by the World Health Organization, which indicated that Bone River water is not safe for drinking or cooking purposes.
Highlights
Heavy metals are produced from natural and anthropogenic sources and can build-up in sediments, having significant environmental implications for local communities, as well as for river water quality [1]
Miners in artisanal small-scale gold mines (ASGM) have used cyanide instead of mercury for gold extraction since 1889 [8,9,10,11], as was the case in Huanca village, Peru, where mercury and arsenic concentrations were found in surface soil samples of the area of Huanca settlement and the agricultural land adjacent to the Acarí River
The present study was conducted along Bone River, which is located in the eastern part of Gorontalo, Indonesia
Summary
Heavy metals are produced from natural and anthropogenic sources and can build-up in sediments, having significant environmental implications for local communities, as well as for river water quality [1]. Gold mining is a source of heavy metals, one of the most serious environmental problems in the world. Artisanal small-scale gold mines (ASGM) are an important source of heavy metals because the extracted material may contain harmful metals, such as As and Pb. ASGM commonly use Hg for gold extraction because it is quite cheap, can be handled and can form an amalgam with gold. Miners in ASGM have used cyanide instead of mercury for gold extraction since 1889 [8,9,10,11], as was the case in Huanca village, Peru, where mercury and arsenic concentrations were found in surface soil samples of the area of Huanca settlement and the agricultural land adjacent to the Acarí River. It was suggested that those concentrations were linked to the gold ore as they reached maximum concentrations (48.4 mg·kg−1 )
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