Park Jeong-Hun, Feng Yucheng, Cho Sung Yong, Voice Thomas C, Boyd Stephen A
Department of Environmental Engineering, Chonnam National University, Kwang-Ju 500-757, South Korea.
Water Res. 2004 Nov;38(18):3881-92. doi: 10.1016/j.watres.2004.06.026.
Soil-chemical contact time (aging) is an important determinant of the sorption and desorption characteristics of the organic contaminants and pesticides in the environment. The effects of aging on mechanism-specific sorption and desorption of atrazine were studied in soil and clay slurries. Sorption isotherm and desorption kinetic experiments were performed, and soil-water distribution coefficients and desorption rate parameters were evaluated using linear and non-linear sorption equations and a three-site desorption model, respectively. Aging time for sorption of atrazine in sterilized soil and clay slurries ranged from 2 days to 8 months. Atrazine sorption isotherms were nearly linear (r(2)>0.97) and sorption coefficients were strongly correlated to soil organic carbon content. Sorption distribution coefficients (K(d)) increased with increase in age in all five soils studied, but not for K-montmorillonite. Sorption non-linearity did not increase with increase in age except for the Houghton muck soil. Desorption profiles were well described by the three-site desorption model. The equilibrium site fraction (f(eq)) decreased and the non-desorbable site fraction (f(nd)) increased as a function of aging time in all soils. For K-montmorillonite, f(nd) approximately 0 regardless of aging, showing that aging phenomena are sorbent/mechanism specific. In all soils, it was found that when normalized to soil organic matter content, the concentration of atrazine in desorbable sites was relatively constant, whereas that in non-desorbable site increased. This, and the lack of aging effects on desorption from montmorillonite, suggests that sorption into non-desorbable sites of soil organic matter is primary source of increased atrazine sorption in soils during aging.
土壤 - 化学接触时间（老化）是环境中有机污染物和农药吸附与解吸特性的重要决定因素。研究了老化对阿特拉津在土壤和黏土悬浮液中特定机制吸附和解吸的影响。进行了吸附等温线和解吸动力学实验，分别使用线性和非线性吸附方程以及三位点解吸模型评估土壤 - 水分配系数和解吸速率参数。阿特拉津在灭菌土壤和黏土悬浮液中的吸附老化时间为2天至8个月。阿特拉津吸附等温线接近线性（r²>0.97），吸附系数与土壤有机碳含量密切相关。在所研究的所有五种土壤中，吸附分配系数（Kd）随老化时间增加而增大，但蒙脱石的Kd并非如此。除霍顿腐泥土外，吸附非线性并未随老化时间增加而增强。三位点解吸模型能很好地描述解吸曲线。在所有土壤中，平衡位点分数（feq）随老化时间降低，不可解吸位点分数（fnd）随老化时间增加。对于蒙脱石，无论老化情况如何，fnd约为0，表明老化现象具有吸附剂/机制特异性。在所有土壤中发现，以土壤有机质含量归一化后，可解吸位点中阿特拉津的浓度相对恒定，而不可解吸位点中的浓度增加。这一点以及老化对蒙脱石解吸无影响表明，土壤有机质不可解吸位点的吸附是老化过程中土壤中阿特拉津吸附增加的主要来源。
