metal concentrations / toxic metal release / large scale mercury mining / geothermal systems / metal sulfides / water-cooled condensing systems / scale mercury mining / open stope mining / mine site / base metal composition / furnace site / ore metal / ore processing furnaces / chemical processes / precious metal ores / food web / base metal loading / precious metal district / base-metal concentrations / mining / trace metal present / ore processing / base metal concentrations / /