Ling Wan-Ting, Wang Hai-Zhen, Xu Jian-Ming, Gao Yan-Zheng
College of Environmental and Natural Resource Sciences, Zhejiang University, Hangzhou 310029, China.
J Environ Sci (China). 2005;17(3):478-82.
The dissolved organic matter (DOM), water soluble organic matter derived from sewage sludge was separated into hydrophobic fraction (Ho) and hydrophilic fraction (Hi). The sorption of DOM and its fractions on soils and the effects of DOM sorption on a nonionic pesticide (atrazine(2-chloro-4-ethylamino-6-isopropylamino-1,3,5-trazine)) distribution between soil and water were investigated using a batch equilibrium technique. The total DOM sorption on soils described by the Langmuir equation reached saturation as the DOM concentration increased. The sorption of Ho fit the Freundlich model. In contrast, a negative retention evidently occurred as adding Hi at higher level in tested soils. The sorption of Ho dominated the total DOM sorption and the release of soil organic matter (SOM). Effects of DOM on the atrazine sorption by soils were DOM-concentration dependent and dominated by the interaction of atrazine, DOM, and soil solids. Generally, the presence of DOM with lower concentration promoted atrazine sorption on soils, namely the apparent partitioning constant (Kd) for atrazine sorption in the presence of DOM was larger than the distribution constant (Kd) without DOM; whereas the presence of DOM with higher concentration inhibited atrazine sorption (i.e., Kd < Kd). The overall effects of DOM on atrazine sorption in soils might be related to the DOM sorption and the release of soil intrinsic organic matter into aqueous solution. The sorption of Ho on soils promoted the atrazine sorption on soil, while the release of SOM by Hi and the competitive sorption between Hi and atrazine on soil surface led to a decrease of atrazine sorption. Information provided in this work may contribute to a better understanding of the DOM sorption and its impacts on the contaminant soil-water distribution.
从污水污泥中提取的水溶性有机物质——溶解有机物（DOM）被分离成疏水组分（Ho）和亲水组分（Hi）。采用批次平衡技术研究了DOM及其组分在土壤上的吸附以及DOM吸附对非离子型农药（阿特拉津（2-氯-4-乙氨基-6-异丙氨基-1,3,5-三嗪））在土壤和水之间分配的影响。用朗缪尔方程描述的DOM在土壤上的总吸附量随着DOM浓度的增加而达到饱和。Ho的吸附符合弗伦德利希模型。相反，在测试土壤中较高水平添加Hi时明显出现了负吸附。Ho的吸附主导了DOM的总吸附以及土壤有机质（SOM）的释放。DOM对土壤吸附阿特拉津的影响取决于DOM浓度，并且主要由阿特拉津、DOM和土壤固体之间的相互作用决定。一般来说，较低浓度的DOM的存在促进了阿特拉津在土壤上的吸附，即存在DOM时阿特拉津吸附的表观分配系数（Kd）大于不存在DOM时的分配系数（Kd）；而较高浓度的DOM的存在则抑制了阿特拉津的吸附（即Kd < Kd）。DOM对土壤中阿特拉津吸附的总体影响可能与DOM的吸附以及土壤固有有机质向水溶液中的释放有关。Ho在土壤上的吸附促进了阿特拉津在土壤上的吸附，而Hi导致的SOM释放以及Hi和阿特拉津在土壤表面的竞争吸附导致了阿特拉津吸附的减少。这项工作中提供的信息可能有助于更好地理解DOM的吸附及其对污染物在土壤-水之间分配的影响。
