Accumulation of Arsenic by Plants Growing in the Sites Strongly Contaminated by Historical Mining in the Sudetes Region of Poland

The uptake of As by various plants growing in highly enriched sites was examined in order to identify potential As accumulators and to assess the risk associated with As presence in plant shoots. Representative samples of 13 plant species, together with soil samples, were collected from various sites affected by historical As mining: mine and slag dumps, tailings and contaminated soils with As concentrations in a range 72-193,000 mg/kg. Potentially and actually soluble As forms, extracted with 0.43 M HNO3 and, 1M NH4NO3 were examined in relation to As concentrations in plant roots and shoots. The latter differed strongly among the species and within them and were in the ranges 2.3-9400 mg/kg and 0.5-509 mg/kg, respectively. The majority (over 66%) of plant samples had As shoot concentrations above 4 mg/kg, an upper safe limit for animal fodder. The uptake of As by plants correlated well with total and extractable soil As, though As concentrations in plants could not be predicted based on soil parameters. Equisetum spp. and C. epigejos indicated a particularly strong accumulation of As in shoots, while A. capillaris, and H. lanatus showed a limited As root-to-shoot transfer, apparently associated with species-related tolerance to As.