基于原位被动采样技术研究巢湖沉积物和水体中PAHs的垂直分布及其界面交换  

Vertical distributions and sediment-water diffusion fluxes of polycyclic aromatic hydrocarbons (PAHs) in Chaohu Lake using an in-situ passive sampler

作　　者：彭书传[1] 黄亚龙 朱曙光 王继忠 PENG Shuchuan;HUANG Yalong;ZHU Shuguang;WANG Jizhong(School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009;School of Environment and Energy Engineering, Anhui Jianzhu University, Hefei 230601;Provincial Key Laboratory of Water Pollution Control and Waste Water Utilization, Hefei 230601)

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009 [2]安徽建筑大学环境与能源工程学院,合肥230601 [3]水污染控制与废水资源化安徽省重点实验室,合肥230601

出　　处：《环境科学学报》2019年第2期491-498,共8页Acta Scientiae Circumstantiae

基　　金：国家自然科学基金(No.41390244;41772035);安徽省科技重大专项(No.16030801118)

摘　　要：沉积物-水体界面处分子扩散是污染物的一个重要地球化学过程,也是判断沉积物是否为上层水体中污染物汇或源的主要依据.本研究利用低密度聚乙烯膜(LDPE)为吸附相的原位被动采样器,同步确定了巢湖西半湖南淝河入湖口处不同深度的上层水体和沉积物孔隙水中13种多环芳烃(PAHs)浓度,并计算了它们在沉积物-水体界面的分子扩散通量.结果表明,3种性能参考化合物(PRCs)在上层水体中的解析速率较沉积物孔隙水中大,相应地,水体中LDPE膜对PAHs的吸附速率高于沉积物孔隙水.水体中13种PAHs总浓度(130～250 ng·L^(-1))低于沉积物孔隙水(180～253 ng·L^(-1)),且均以低环PAHs为主.2～3环PAHs浓度在上层水体中无明显的垂直变化,但4～6环PAHs浓度呈现随深度增加而降低的趋势.沉积物孔隙水中PAHs浓度的垂直变化规律反映了历史强排放过程.研究区域PAHs在沉积物-水体界面的交换通量变化范围为-384～1445 ng·m^(-2)·d^(-1),除Flu和Pyr外,其它PAHs均从沉积物向水体释放,反映了底部沉积物是上层水体中PAHs的重要二次污染源.Molecular diffusion across the sediment-water interface is an important geochemical processes, which determines whether sediment is a source or sink of pollutants in water body. In the present study, the vertical concentrations of 13 PAHs in both water column and sediment porewater were determined using an in-situ passive sampler with LDPE as the sorbent phase. The diffusion fluxes of PAHs between sediment-water interface were calculated. Results showed that desorption rates of 3 PRCs in overlying water were significantly larger than those in sediment porewater, correspondingly,the rates of absorption of PAHs in overlying water were greater than those in sediment porewater. The summed concentrations of 13 PAHs in overlying water(130~250 ng·L^-1) were lower than those in the sediment porewater(180~253 ng·L^-1),and PAHs were dominated by low molecular weight PAHs. The concentrations of 2~3 rings PAHs in overlying water were consistent vertically,but 4~6 rings PAHs tended reducing trends with the increasing depth. Vertical profiles in sediment porewater indicated that a large amount of PAHs were discharged in this area in history. The diffusion fluxes of PAHs ranged from-384 ng·m-2·d^-1 for Pyr to 1445 ng·m^-2·d^-1 for Ac. Except for Flu and Pyr, reminding PAHs were released from bottom sediment to overlying water. Therefore, the bottom sediment of Chaohu Lake is an important secondary source of PAHs in overlying water.

关 键 词：多环芳烃 原位被动采样 沉积物孔隙水 分子扩散 通量 

分 类 号：X821[环境科学与工程—环境工程] X131.2