Xia Xing-hui, Zhang Ju, Sha Yu-juan
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
Huan Jing Ke Xue. 2010 Apr;31(4):969-75.
Irreversible sorption behavior of two phthalate acid esters (PAEs), Dimethyl phthalate (DMP) and Di-(2-ethyl-hexyl) phthalate (DEHP), on four natural sediment samples from the Yangtze River and the Yellow River has been studied by equilibrium sorption and multiple cycles of adsorption/desorption experiments. The equilibrium sorption experiment results showed that the organic carbon-normalized partition coefficients (lgKoc) of DMP and DEHP were higher than those reported in references. This means that the sorption of DMP and DEHP on natural sediments include other sorption mechanisms besides the linear partition on organic carbon. The multiple cycles of adsorption/desorption experiment results showed that the sorption of PAEs included linear reversible sorption and irreversible sorption. For the four sediment samples, the maximum of irreversible sorption capacities were 125.19-337.37 microg/g and 515.89-591.41 microg/g for DMP and DEHP, respectively, which were positive correlated to the surface areas, cation exchange capacity and black carbon content of the sediments. The OC-normalized partition constants for the reversible compartment (lgk(oc)(rev)) were 3.69-4.98 L/kg for DMP; they were higher than those (lgKoc) reported in references, suggesting other reversible sorption mechanisms exist besides the linear partition on organic carbon. The lgk(oc)(rev) were 4.12-5.31 L/kg for DEHP; they were close to those (lgKoc) reported in references, suggesting the linear partition on organic carbon is the main reversible sorption mechanism. Although the physiochemical properties of DMP and DEHP are different, the OC-normalized partition constant for the irreversible compartment on the four sediments is essentially constant with lgk(oc)(rev) = (6.46 +/- 0.38) L/kg. As irreversible sorption exists for PAEs, the maximum of irreversible sorption capacity should be considered when studying the sediment quality criteria.
通过平衡吸附和多次吸附/解吸循环实验，研究了邻苯二甲酸二甲酯（DMP）和邻苯二甲酸二（2-乙基己基）酯（DEHP）这两种邻苯二甲酸酯在长江和黄河的四个天然沉积物样品上的不可逆吸附行为。平衡吸附实验结果表明，DMP和DEHP的有机碳归一化分配系数（lgKoc）高于参考文献中报道的值。这意味着DMP和DEHP在天然沉积物上的吸附除了有机碳上的线性分配外，还包括其他吸附机制。多次吸附/解吸循环实验结果表明，PAEs的吸附包括线性可逆吸附和不可逆吸附。对于这四个沉积物样品，DMP和DEHP的不可逆吸附容量最大值分别为125.19 - 337.37 μg/g和515.89 - 591.41 μg/g，它们与沉积物的表面积、阳离子交换容量和黑碳含量呈正相关。可逆部分的OC归一化分配常数（lgk(oc)(rev)）对于DMP为3.69 - 4.98 L/kg；高于参考文献中报道的值，表明除了有机碳上的线性分配外还存在其他可逆吸附机制。对于DEHP，lgk(oc)(rev)为4.12 - 5.31 L/kg；与参考文献中报道的值接近，表明有机碳上的线性分配是主要的可逆吸附机制。尽管DMP和DEHP的物理化学性质不同，但四种沉积物上不可逆部分的OC归一化分配常数基本恒定，lgk(oc)(rev) = (6.46 ± 0.38) L/kg。由于PAEs存在不可逆吸附，在研究沉积物质量标准时应考虑不可逆吸附容量的最大值。
