土壤不同粒级中Cr(Ⅵ)生物可给性及健康风险

Bioaccessibility and Health Risk of Cr(Ⅵ)in Different Particle Size Fractions of Soils

为定量分析土壤不同粒级中Cr(Ⅵ)的健康风险,将铬污染土壤筛分为粗砂(500~1000μm)、中砂(250~500μm)、细砂(100~250μm)、粗粉砂(50~100μm)、粉砂及以下(0~50μm),利用激光粒度分析仪、积累因子法(accumulation factors,AF)及基于生理的提取实验(physiologically based extraction test,PBET)研究不同粒级质量分布、Cr(Ⅵ)分布特性及Cr(Ⅵ)生物可给性,并采用美国环境保护局(United States Environmental Protection Agency,US EPA)推荐的暴露模型评价Cr(Ⅵ)通过经口摄入途径引起的健康风险。结果表明,土壤不同粒级组分间Cr(Ⅵ)积累因子分布与Cr(Ⅵ)含量分布规律一致,碱性土壤中Cr(Ⅵ)倾向于在粗颗粒内积累;考虑生物可给性的情况下,Cr(Ⅵ)产生的健康风险下降43.65%~99.19%;细砂组分对Cr(Ⅵ)经口摄入的健康风险贡献最大,为48%~78%,说明粒级质量占比和生物可给性越高,其对健康风险的贡献越大。本研究量化了粒级质量分布对健康风险贡献的大小,这有利于识别影响健康风险的主要粒级组分,提高铬污染土壤健康风险评估的可靠性。

In order to quantitatively analyze the health risks of Cr(Ⅵ)in different soil particle fractions,the chromium-contaminated soils was sieved into coarse sand(500~1000μm),medium sand(250~500μm),fine sand(100~250μm),coarse silt(50~100μm),silt and below(0~50μm)in this research.The mass distribution of soil particle,Cr(Ⅵ)distribution characteristics and bioaccessibility were studied by laser particle size analyzer,accumulation factors(AF)and physiologically based extraction test(PBET),and the health risks of Cr(Ⅵ)via oral intake were evaluated by the exposure model introduced by United States Environmental Protection Agency(US EPA).The results showed that the distribution of Cr(Ⅵ)accumulation factor was consistent with the distribution of Cr(Ⅵ)content in different size fractions,and Cr(Ⅵ)tended to be accumulated in coarse particle in alkaline soil.The health risk of Cr(Ⅵ)was decreased by 43.65%~99.19%under consideration of the bioaccessibility.The fine sand fraction contributed the most to the health risks caused by oral intake of Cr(Ⅵ),ranging from 48%to 78%.This indicated that the soil particle fractions with higher proportion of particle mass and bioaccessibility may contribute more to health risks.This research quantified the contribution of particle mass distribution to health risks,which was helpful to identify the main particle fractions affecting health risks,and could improve the reliability of the health risk assessment of chromium-contaminated soils.