Department of Environmental Science, Institute for Water and Wetland Research, Radboud University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands.
Chemosphere. 2013 Jan;90(2):312-7. doi: 10.1016/j.chemosphere.2012.07.014. Epub 2012 Aug 9.
Freshwater fate and exposure factors were determined for organic acids and bases, making use of the knowledge on electrical interaction of ionizing chemicals and their sorption to particles. The fate factor represents the residence time in the environment whereas exposure factors equal the dissolved fraction of a chemical. Multimedia fate, exposure, and effect model USES-LCA was updated to take into account the influence of ionization, based upon the acid dissociation constant (pK(a)) of a chemical, and the environmental pH. Freshwater fate (FF) and exposure (XF) factors were determined for 415 acids and 496 bases emitted to freshwater, air, and soil. The relevance of taking account of the degree of ionization of chemicals was tested by determining the ratio (R) of the new vs. fate and exposure factors determined with USES-LCA suitable for neutral chemicals only. Our results show that the majority of freshwater fate and exposure factors of chemicals that are largely ionized in the environment are larger with the ionics model compared to the factors determined with the neutrals model version. R(FF) ranged from 2.4×10(-1) to 1.6×10(1) for freshwater emissions, from 1.2×10(-2) to 2.0×10(4) for soil emissions and from 5.8×10(-2) to 6.0×10(3) for air emissions, and R(XF) from 5.3×10(-1) to 2.2×10(1). Prediction of changed solid-water partitioning, implying a change in runoff and in removal via sedimentation, and prediction of negligible air-water partition coefficient, leading to negligible volatilization were the main contributors to the changes in freshwater fate factors.
利用离子化化学物质的电相互作用及其对颗粒的吸附知识，确定了有机酸和碱基的淡水归宿和暴露因子。归宿因子代表在环境中的停留时间，而暴露因子则等于化学物质的溶解部分。基于化学物质的酸离解常数（pK(a)）和环境 pH 值，对考虑电离影响的多介质归宿、暴露和效应模型 USES-LCA 进行了更新。确定了向淡水、空气和土壤排放的 415 种酸和 496 种碱的淡水归宿（FF）和暴露（XF）因子。通过确定新的与仅适用于中性化学物质的 USES-LCA 确定的归宿和暴露因子的比率（R），测试了考虑化学物质电离程度的相关性。我们的结果表明，在环境中大部分电离的化学物质的淡水归宿和暴露因子在离子模型中比在中性模型版本中更大。对于淡水排放，R(FF)的范围为 2.4×10(-1)至 1.6×10(1)，对于土壤排放，R(FF)的范围为 1.2×10(-2)至 2.0×10(4)，对于空气排放，R(FF)的范围为 5.8×10(-2)至 6.0×10(3)，而 R(XF)的范围为 5.3×10(-1)至 2.2×10(1)。改变固-水分配的预测，意味着径流量的变化和通过沉淀去除的变化，以及可忽略的气-水分配系数的预测，导致可忽略的挥发，这是淡水归宿因子变化的主要原因。
