THE BEHAVIOR AND TRANSFER OF ARSENIC AND ANTIMONY FROM GOLD MINING OPERATIONS ON AQUATIC SYSTEMS, TADPOLES AND OTHER ORGANISMS

Stibnite Mine near Yellow Pine, Idaho, is an historical location of gold, antimony, and tungsten mining. Mining began in 1931, and is currently restricted to gold extraction. Tailing piles from past mining activity release high (mg/L) concentrations of arsenic (As) and antimony (Sb) to Meadow Creek and to seeps and springs located near the mine. Although a number of studies have examined As levels around mining sites, the toxicity effects and behavior of As in freshwater organisms and in food webs is still poorly understood (Dushenko et al., 1995; Fu et al., 2010). Antimony, a toxic element of emerging global concern, has received even less attention. Here we report concentrations and redox speciation of As and Sb in water, tadpoles, and other aquatic organisms from Meadow Creek and surrounding seeps and springs from 2010 and 2011. Total As and Sb concentrations in biological samples were analyzed by ICP-MS following acid digestion. Arsenic and Sb redox species were extracted from biological samples with H₂O/MeOH extraction and measured by HPLC-ICP-MS. Water from Meadow Creek and the surrounding seeps and springs had As concentrations ranging from 1.4 ppb (upstream reference point) to 26,214 ppb (seep next to tailing pile). Antimony water levels ranged from 0.3 ppb (upstream reference point) to 1,152 ppb (seep next to tailing pile). Tadpole total body As concentration ranged from 0.2 ppm in upstream reference reaches to 2,061 ppm in highly contaminated tailings seep sites. Surprisingly, inorganic As(III) was found to predominate over less toxic forms including As(V), MMA, DMA, and As-betaine in Meadow Creek tadpoles. Aquatic organisms in this study show elevated As and Sb levels from sites with elevated surface water concentrations. Despite high As and Sb total body concentrations in tadpoles, field observations suggest complete metamorphism from tadpole to frog.