Evaluation of Mercury Concentration in Water and Sediment at Artisanal Buladu Gold Mine in Gorontalo Province, Indonesia

The research is aimed to investigate the spread of mercury concentration in the water and the sediment as the result of Artisanal Buladu gold mine activity in North Gorontalo Regency, Indonesia. Randomly sample taking was conducted in Pasolo/Hulawa River, Sulawesi Sea, and tailing waste with three times sampling repetition. The total samples of water and sediment were 94 samples. The analysis of mercury sample in the water and in the sediment was done in Integrated Research and Test Laboratory by using mercury analyzer and with AAS without any flame. The quality standard that becomes the reference for river water is Government Law 82 year 20110 Class I in which requirement is not more than 0.001 mg/l. The sea water uses Environment Ministry Decree No 51 Year 2004 with 0.001 mg/l. The quality standard of waste water uses Environment Ministry Decree No 202/2004 with the standard not more than 0.005 mg/l. The quality standard used in the sediment uses European safety standard with not more than 2 ppm.

The result of the analysis shows that mercury concentration in the sampling of river water I, II, and III were between 0.0006 – 0.00035 mg/l, 0.00063 –2.4284 mg/l and smaller than 0.06 ug/l. Sea water Sampling I, II and III were around 0.00025 – 0.00188 mg/l, 0.00063 – 1.1122 mg/l and 0.00034 – 0.00141 mg/l. In the Tailing, the result was around 0.00046 – 0.00339 mg/l, between 0.0033 – 0.9423 mg/l and 0.00053 – 0.07003 mg/l. Based on the result, it can be seen that mercury concentration in the water was above the quality standard. The mercury concentration in the sediment in sampling I, II and III in the river was around 10.8731 – 55.0680, 0.08995 – 136.70 and 0.55255 – 244.16 mg/kg. The sea sediment was around 8.7870 – 25.4630, 0.24190– 1.87 0.27745– 1.00 mg/kg. The concentration in the tailing was around 10.0643 – 36.4008, 3.31 – 135.55 and 104.36 – 236.22 mg/kg. Based on this result, mercury concentration in the sediment has been above the quality standard that has been required. It means that the mining activity needs a maximum management to overcome high level of mercury pollution.