Long-term nonferrous metal smelting affects metal accumulation/transfer in a soil-plant-woodlouse system

Nonferrous metal smelting is one of the main sources of heavy metal pollution in the environment, yet its effect on heavy metal transfer in soil-plant-animal systems is not well investigated. In this work, soil, plant (Humulus scandens [HS], Digitaria sanguinalis [DS], and Setaria viridis [SV]), and woodlouse (Armadillidium vulgare) samples were collected in a long-term nonferrous metal smelting area from 26 sites over approximately 7 km and analyzed for Cd, Cu, Mn, Ni, Pb, and Zn concentrations. Cadmium and Pb were the most accumulated soil metals, with mean concentrations of 4.68 and 249 mg kg^-1, respectively. The plant bioconcentration factor (BCF) of soil heavy metals was all <1. Mean woodlouse Cd, Cu, Mn, Ni, Pb, and Zn concentrations were 20.5, 69.7, 169, 5.41, 47.2, and 424 mg kg^-1, respectively. Significant correlations between woodlouse heavy metal concentrations and distances from the smelter were only found for Cd. Woodlice had a greater BCF of plant Cd (mean = 11.2), Cu (52.6), and Zn (10.6) than for Mn, Ni, and Pb. No significant correlation was found between soil/plant and woodlouse for heavy metal concentrations. Heavy metal toxicities to plants and woodlice were quantitatively estimated with a newly developed model, with results indicating that woodlice had much greater (9800) values than the plants (<1300). Results indicate enhanced accumulation and toxicity of heavy metals to woodlouse in the soil-plant-woodlouse system than in a simpler soil-plant system approach. The health risks of heavy metals in woodlice to predators need further evaluation.