Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
Environ Sci Technol. 2011 Feb 1;45(3):1127-32. doi: 10.1021/es1025849. Epub 2010 Dec 22.
A previous study on mobilization of organochlorine pesticides (OCPs) in contaminated soils from the field revealed that the total amount of OCPs measured in digestive fluid and chyme of an in vitro gastrointestinal model was higher than the quantity directly extracted using a solvent extraction without digestion, providing a clue that the bound residue of OCPs might be mobilized. This hypothesis was tested in this study for both OCPs and polycyclic aromatic hydrocarbons (PAHs). Three contaminated surface soil samples with different organic carbon (OC) contents were collected from the field, and extracted with a solvent with and without digestion in an in vitro gastrointestinal model. It was found that bound residues of OCPs and PAHs were mobilized to a certain extent during digestion. The ratios of the mobilized bound residues over the total quantities extracted after digestion (R(b)) varied from 0 to 0.96 for individual compounds. The R(b) was positively correlated with OC content. Among the five constitutes of digestive juice, bile salt was the only one that served to mobilize the bound residues and the extractability of bile salt was constant over a concentration range from 2 to 20 mg/mL. The mobilization process followed typical first-order kinetics. The calculated rate constants suggest that mobilization was fast and 90% of extracted bound residues of OCPs and PAHs were mobilized within 2.4 and 4.8 h, respectively.
先前对田间受污染土壤中有机氯农药（OCPs）的迁移研究表明，体外胃肠模型中消化液和食糜中测量的 OCPs 总量高于不经过消化直接使用溶剂提取的数量，这提供了一个线索，即 OCPs 的结合残留可能会被迁移。本研究针对 OCPs 和多环芳烃（PAHs）对此假设进行了验证。从田间采集了三个具有不同有机碳（OC）含量的受污染表层土壤样品，并在体外胃肠模型中用溶剂进行提取，同时进行消化。结果发现，在消化过程中，OCPs 和 PAHs 的结合残留会在一定程度上被迁移。消化后提取的总结合残留量（R(b)）与消化后提取的总结合残留量（R(b)）之比（R(b)）从单个化合物的 0 到 0.96 不等。R(b)与 OC 含量呈正相关。在五种消化液成分中，胆盐是唯一能够迁移结合残留的成分，并且在 2 至 20mg/ml 的浓度范围内胆盐的提取率保持不变。迁移过程遵循典型的一级动力学。计算出的速率常数表明，迁移速度很快，90%的 OCPs 和 PAHs 的提取结合残留分别在 2.4 和 4.8 小时内被迁移。
