作　　者： ; ; ; ; ; ;

机构地区： 华南理工大学环境科学与工程学院

出　　处： 《环境科学学报》 2010年第12期2471-2478,共8页

摘　　要： 疏水性有机污染物在沉积物上的吸附-解吸行为直接决定其在水环境中迁移、转化、生物效应与归宿.以往采用背景电解质溶液作为解吸体系的方法,忽略了其与天然水体水化学条件的差异可能对污染物的解吸行为产生的影响,从而造成疏水性有机污染物在天然水体沉积物上的吸附-解吸性能评价方法存在较大偏差.本文通过选用沉积物浸出液代替背景电解质溶液的方式来保证吸附-解吸水化学条件的一致性,采用批量平衡的方法对分别采集于凉水河水系(标记为L)以及东江流域(标记为D)的两种河流沉积物样品,进行连续吸附-解吸实验,以考察多环芳烃萘在沉积物上的吸附-解吸规律,从而阐明水化学条件的一致性对吸附-解吸过程的影响与重要性.实验结果表明,萘在沉积物上的吸附-解吸过程呈现出明显的滞后现象.传统的以背景电解质溶液作为介质,研究疏水性有机污染物解吸行为的方法会导致解吸体系的TOC值比模拟天然水体体系减少74.68%～85.01%,这种吸附-解吸水化学条件的差异会增强污染物在沉积物上的滞后性,具体表现为萘在沉积物L和D浸出液中的平均解吸量相比其在背景电解质溶液中分别增加了3.14mg·kg-1和2.40mg·kg-1,平均解吸滞后系数由在背景电解质溶液中的0.04和0.135降低至沉积物浸出液中的0.012和0.072.此现象表明,与纯电解质溶液比较,采用从沉积物中提取的溶解有机碳作为解吸介质,会显著增加萘在沉积物中的平均解吸量,所获得的实验结果更加符合天然水体的实际条件. Sorption and desorption of hydrophobic organic compounds（HOCs） on natural sediments plays an important role in the fate,transport,bioavailability,and toxicity of these compounds.The general methods using blank electrolyte（such as CaCl2 and NaN3 solvent） as desorption system ignore the influence of different aqueous chemical conditions on the pollutant desorption behavior,which can lead to large deviations of sorption and desorption in aquatic environments.In this study,blank electrolyte was replaced with sediment extract to guarantee the aqueous solution consistency.Batch equilibrium experiments were carried out to investigate the sorption and desorption behavior of naphthalene on and from two representative sediments（denoted as L and D）.The results show that the sorption and desorption of naphthalene from sediments exhibit obvious hysteresis as described by the hysteresis index（HI）.Traditional desorption methods decreased the TOC by 74.68% ～ 85.01% as compared with extracts.Greater hysteresis exists in the blank electrolyte than in the sediment extracts,as indicated by the larger HI values of 0.04 and 0.135 in blank electrolyte than those of 0.012 and 0.072 in the sediment extracts for sediments L and D respectively.The average concentration of TOC in the extracts increased 3.14 and 2.40 mg·kg-1 more than in blank electrolyte.These results demonstrate that the average desorption of naphthalene increased significantly in sediment extract,and the results should be more in accord with natural water conditions.

关 键 词： 沉积物 萘 吸附 解吸滞后

领　　域： [环境科学与工程]