有机污染物在长江三角洲城市群典型沉积物中的迁移行为

Migration behavior of organic pollutants in typical sediments of the Yangtze River delta urban agglomeration

长江三角洲城市群地区是中国沉积类型种类相对多、岩性类型复杂的地质区域。改革开放以来该地区化工企业快速发展,使有机化工产品泄漏到土壤和沉积物中的风险加大,对环境构成了较大的安全隐患,因此,掌握污染物在土壤和沉积物中的迁移转化规律对后续开发利用具有实用意义。采集并分析了长江三角洲城市群4种代表性的沉积物,以邻氯甲苯为代表开展了有机污染物在沉积物中迁移行为的研究,并利用SPSS软件建立邻氯甲苯吸附量与沉积物理化性质之间的相关方程。研究结果表明:长江三角洲城市群湖积相、湖沼积相、冲湖积相和冲积相沉积物的有机质含量直接控制其对邻氯甲苯的吸附阻滞能力,土壤的pH、矿物成分、阳离子交换量对邻氯甲苯的吸附能力影响不大,苏州的湖积和湖沼积沉积物中有机质含量较高(7~63 g/kg),其对邻氯甲苯的吸附阻滞能力较强,而南京、镇江等地的冲积沉积物和常州、江阴南部的冲湖积沉积物中有机质含量较低(4~15 g/kg),对邻氯甲苯的吸附能力较弱,使污染物更易迁移;Freundlich模型能够较好地拟合不同种类沉积物对邻氯甲苯的等温吸附过程,表征吸附强度的系数K_(F)与沉积物的有机质含量呈显著正相关,有机质含量越大,K_(F)值越大,沉积物对邻氯甲苯的吸附强度越强,邻氯甲苯的等温吸附过程线性程度越高。研究成果将有利于预测有机污染物在长江三角洲城市群地区不同种类沉积物中的吸附行为,为治理污染和调整工业布局提供理论依据。

The Yangtze River delta urban agglomeration is a geological region with many sedimentary types and complex lithology types.Since the reform and opening up,the rapid development of chemical enterprises in this area has increased the risk of leakage of organic chemical products into soil and sediment.It poses a great potential safety hazard to the environment.Therefore,mastering the migration and transformation of pollutants in soil and sediment has practical significance for the subsequent development and utilization of these plots.The organic chemical industry is well developed in the Yangtze River delta urban agglomeration.Organic pollution of soil and groundwater in brownfield is serious.The physical and chemical properties of the soil in brownfield control the extent of contamination.Four representative sediments from the Yangtze River delta urban agglomeration were collected and analyzed in this paper.The physical and chemical properties of sediment affecting o-chlorotoluene migration were analyzed based on the study of differentiation between sediments and the statistic software SPSS.The result of research shows that the Yangtze River delta urban agglomeration can be divided into alluvial,lacustrine,lacustrine-swamp and alluvial sedimentary areas.The adsorption capacity of o-chlorotoluene was directly controlled by the organic content of the sediment matrix.The cation exchange capacity,mineral composition and pH of soil had little effect on the adsorption capacity of o-chlorotoluene.The content of organic matter in the lacustrine and lacustrine-swamp sediments in Suzhou is relatively high(7~63 g/kg),and its adsorption capacity of o-chlorotoluene is strong.In Nanjing,Zhenjiang and south of Changzhou,Jiangyin where the alluvial sediments and alluvial-lacustrine sediments developed,the adsorption strength of o-chlorotoluene to the sediments is weak as its low organic matter content(4~15 g/kg),making the pollutants easier to migrate.The Freundlich model can fit the isothermal adsorption process of o-chlorotoluene on the four kinds of sediment samples well.The parameters K_(F) characterizing the adsorption strength in the model was significantly positive correlated with the content of organic matter in sediments.The higher the organic matter content,the higher the K_(F) value,the stronger the adsorption strength of the sediments to o-chlorotoluene,the higher the linearity of the isothermal adsorption process.The study will be helpful to predict the adsorption behavior of organic pollutants in different sediments in the Yangtze River delta urban agglomeration and provide scientific theoretical basis for controlling pollution and adjusting industrial layout.