土壤中铜与阿特拉津交互作用下的吸附行为研究

农业土壤中重金属-有机农药复合污染普遍存在,以常见的重金属污染元素铜和具有代表性的三嗪类除草剂阿特拉津(AT)为目标物,通过批量平衡吸附实验考查了两者共存时的吸附等温线变化,并对交互作用下离子强度、有机质含量和p H值等因素对两者吸附过程的影响进行了研究,以期揭示铜与阿特拉津吸附过程的交互作用规律以及土壤环境因子对吸附交互作用的影响。结果表明:在土壤-水体系中,AT和Cu2+的吸附行为发生了交互影响,Cu2+的存在减小了土壤中AT的吸附;低浓度的AT明显抑制了Cu2+的吸附,而在较高浓度时(≥5 mg·L-1),抑制作用随AT浓度增加而减弱。交互作用下,有机质含量的影响与单一吸附情况相同,有机质含量减少,两者的吸附量皆下降;离子强度和p H值的影响与单一污染相比有所变化,两者的吸附量皆随离子强度增加而减少,其中AT的变化趋势与单独存在时相反;实验范围内,酸性条件对土壤吸附铜的抑制作用变得不再明显。

Cosorption of Cu2+ and atrazine on soil

Batch adsorption experiments were conducted to investigate cosorption behavior of atrazine (AT) and Cu²⁺ on soil. Results showed that the presence of Cu²⁺ significantly decreased AT adsorption on soil and the adsorption data of AT could be well described by Freundlich model (R²=0.9669). The addition of AT also reduced the adsorption amount of Cu²⁺ on soil, with reduction effect being greater at lower AT concentrations (< 5 mg·L^-1). This might be contributed to the formation of AT-Cu²⁺ complex, resulting in a decrease of competitive adsorption. Langmuir equation was the most appropriate model for the adsorption process of Cu²⁺ under the presence of AT. When AT coexisted with Cu²⁺, the adsorption of both AT and Cu²⁺ was positively related with organic matter, which was very consistent with the result of single pollution. However, the adsorption capacities of both AT and Cu²⁺ were reduced by increasing ionic strength, whereas the effect was opposite when AT existed alone. The adsorption amount of Cu²⁺ was not very affected by pH, may due to the complex formation and buffering action of soil.