芜湖市沉积物-水体PAHs扩散行为研究

为研究芜湖市不同功能区景观水体多环芳烃（PAHs）在沉积相-水相之间的扩散行为，于2017年2月选择芜湖市25处景观水体采集沉积物和水样品，对美国环保署（EPA）列为优先控制污染物的16种PAHs进行检测，运用逸度方法、响应系数进行分析.分别考虑有机碳（OC）、BC_CTO（化学热氧化法测定的黑碳）和BC_Cr（湿化学氧化法测定的黑碳）在不同浓度（实测值、最低值、平均值、最大值）情况下对PAHs在沉积相-水相间扩散的影响.结果表明，中低环（2~4环）PAHs表现出向水相扩散，沉积物作为PAHs的二次污染源，高环（5~6环）PAHs表现出向沉积相扩散，沉积物作为PAHs的汇；随着OC和黑碳（BC）含量的增加，PAHs倾向于向沉积相扩散，且倾向程度是BC_Cr > BC_CTO > OC，表明BC在PAHs的沉积物-水扩散过程中起重要的作用.响应系数结果表明中低环PAHs的逸度分数（ff）对OC、BC_CTO和BC_Cr浓度变化的敏感度较弱，高环PAHs的ff对OC、BC_CTO和BC_Cr浓度变化的敏感度较强，且敏感度强弱依次是BC_Cr > BC_CTO > OC.沉积相-水体的扩散过程研究揭示了PAHs在水环境中迁移扩散的重要机理，可为环境污染的科学治理提供依据.

Sediment-water diffusion of PAHs in Wuhu city,China

In order to study the diffusion of polycyclic aromatic hydrocarbons (PAHs) between sediment and water in landscape waters of different functional areas in Wuhu, 25landscape water in Wuhu were selected to collect sediment and water samples in February 2017, 16kinds of PAHs listed as Priority Control Pollutants by the US Environmental Protection Agency (EPA) were tested and analyzed by fugacity method and response coefficient. The effects of total organic carbon (TOC), BC_CTO (black carbon measured by chemical thermal oxidation) and BC_Cr (black carbon determined by wet chemical oxidation) were investigated at different concentrations (measured value, lowest value, average value, maximum value). The results showed that 2-4rings PAHs were diffused from sediment to aqueous, and the sediments were secondary sources of PAHs. 5~6rings PAHs were diffused from aqueous phases to sediment. With the increase of the concentrations of TOC and BC, PAHs tended to diffuse into sediments and the order of sensitivity was BC_Cr > BC_CTO > OC. The diffusion process of sediment-water revealed the important mechanism of migration and diffusion of PAHs in water environment, which could provide basis for the scientific management of environmental pollution.