Concentrations Of Rare Earth Elements And Health Risk Assessment In Soil And Vegetation System

With the development of society and economy, various kinds of natural resource were consumed, leading to ecological environment damages with rapid rate, and arousing a series of environmental and social issues. Sewage discharged in rare earth elements (REEs) mining process has resulted in soil quality decrease, ecology system degenerate and crops production reduction. The REEs in soil would be intaked by human via food chain, and threaten human health Due to the most of rare earth elements enter into farmland soil, and accumulate in the soil surface, REEs has long-term impacted on soil environment and crops. Therefore, the transfer and ecological risk of rare earth element when entering into the soil are currently taken into account.The results showed that the soil nutrients concentrations were low due to the soil suffer from serious destruction. Concentrations of REEs in soils were507.40～841.37mg·kg-1, exceeding the soil background value of Fujian Province. The concentrations of REEs in roots, stem and-leaf of the vegetation were40.27-986.01mg-kg"1,5.14-206.58mg·kg-1and6.81-2364.51mg·kg-1, respectively. The concentrations of REEs in Dicranopteris pedata declined in the order:leaf> stem> root, nevertheless in other vegetations:root> leaf> stem. The uptake of REEs by the plants can be classified into two types according to REEs concentrations in the plant shoots and roots:the accumulator, Dicranopteris pedata, which absorbed a large amount of REEs by the root and transported to leaf; the root compartment, eg. Eucalyptus, Paspalum wettsteinii, Schima and Sasanqua.Concentrations of rare earth elements in cultivated soils and eight vegetables from a mining area of Changting County of Fujian Province were surveyed. The concentrations of REEs in cultivated soils exceeded the soil background value of Fujian Province, while the concentrations of REEs of taro (3.68mg-kg-1fresh weight) and water spinach (0.92mg·kg-1·d-1) exceeded the maximum permissible concentration of REEs in vegetables (0.7mg·kg-1·d-1) in the NFHSC. The concentrations of REEs of the eight vegetables declined in the order:taro> water spinach> lettuce> pakchoi> long bean> eggplant> white radish> Chinese cabbage. REE concentrations of leafy vegetables were higher than those of the non-leafy vegetables. REE concentrations in local resident’s blood and hair were155.6and9.5times higher respectively than those of the general population. The average concentrations of REEs in well water from the mining area were119times higher than those in the drinking water of Fuzhou City. The average daily intake of REEs of local inhabitants was estimated to be12.5mg·kg-1·d-1, exceeding values found to be damaging to human health (6.0-6.7mg·kg-1·d-1). The local inhabitants face health risk due to high REE exposure from vegetable consumption. Some vegetables had greater concentrations of REEs, therefore local farmers should choose vegetables with low REE concentrations for reducing health risk associated with high intake of REEs.