Distribution of Mercury in Soil, Water, and Vegetable Fern in a Former Gold Mining Area – Evidence from Nagan Raya Regency, Aceh Province, Indonesia

Abstract

The mercury contamination associated with the former intense illegal gold mining activities is suspected in the watershed of Krueng Cot Satu, Nagan Raya Regency, Aceh Province, Indonesia. The aim of this study was to evaluate the mercury contamination residue in the water, soil, and vegetable fern (Pityrogramma calometanos (L)) The samples were collected from locations in the already closed artisanal gold mining sites. The sampling locations were purposively determined by considering their closeness to the previous gold mining activities sites. The content of mercury was analyzed using flow injection for atomic spectroscopy – atomic absorption spectroscopy. The method used was validated by linearity, Limit of Detection (LoD), Limit of Quantification (LoQ), Relative Standard Deviation (RSD), and recovery. The validation test showed that this method is well linear, sensitive, accurate, and precise with a correlation coefficient, LoD, LoQ, RSD and recovery of 0.9999, 0.0477 μg/L, 0.1447 μg/L, 2.96% and 95–105%, respectively. Herein, it was found that the concentrations of mercury contents in the water samples were below the detectable range. However, a high range of mercury concentration of 0.236 – 0.328 μg/g was found in soil, with the highest concentration obtained in the sample collected from the riverbank. The fern sample collected near the riverbank contained mercury in all its parts and concentrated in the root (0.408 μg/g in the leaves, 0.276 μg/g – stalks, and 9.994 μg/g – roots). Meanwhile, the absence of mercury contamination was obtained in the leaves and stalks of the fern samples collected far from the riverbank. The roots, however, were detected with mercury contamination with the highest concentration reaching 27.660 μg/g. Despite its disappearance in the water, mercury contamination residue from the former artisanal gold mining activities still could be traced in the soil and heavy metal accumulating plant – P. calometanos (L).