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

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.