Mercury accumulation in sweet potatoes: Effect of gold mine tailing contamination and compost amendment

The effect of compost on mercury content in sweet potatoes grown on soil contaminated by mine tailings was investigated in this study. In a completely randomized factorial design with three repetitions, the sweet potato MZ119 clone was planted on soil with a mixture of tailings at a ratio of 0%, 30%, 50%, 70%, and 100% (w/w) and compost amendment (0 g/pot, 250 g/pot, 500 g/pot, and 750 g/pot). An increase in the tailing contamination ratio led to an increase in mercury accumulation in sweet potatoes. In contrast, an increase in compost dosage reduced mercury accumulation. Compost doses of 500 and 750 g/pot were most effective in reducing mercury accumulation in sweet potatoes. The mercury concentration in sweet potato tubers ranged from 0.153 to 0.802 mg/kg, which is above the threshold required for crops set by the WHO/FAO and other international standards. However, sweet potato plants exhibited a high mercury accumulation potential for mercury phytoremediation purposes, as they can accumulate mercury up to 18.15 mg/kg in their leaves.