环渤海地区2,4,4'-三氯联苯的多介质归趋模拟

为探究多氯联苯(PCBs)在环渤海地区的环境多介质迁移和归趋行为,本研究以2,4,4′-三氯联苯(PCB28)为目标污染物,基于区域尺度多介质城乡逸度模型,模拟了稳态条件下PCB28在各环境相中的浓度分布、总量分配以及相间迁移过程,并对模型的输入参数和输出结果分别进行了敏感性和不确定性分析.结果表明,PCB28在淡水、农村土壤、城市土壤和沉积物中的模拟浓度与实测浓度吻合较好,验证了模型的可靠性.PCB28在城市土壤中的浓度最大,浓度均值为5.26×10~(-6) mol·m~(-3),在农村大气中的浓度最小,浓度均值为5.79×10~(-14) mol·m~(-3).当环境系统达到平衡时,土壤是PCB28最主要的"汇",占其在环境中总储量的96.45%.大气相与其他环境相间的相互迁移过程是PCB28在环渤海地区进行空间迁移的主导过程.大气传输是PCB28最主要的入海途径,从农村大气到海水的迁移通量占总入海通量的97.22%.参数敏感性分析结果表明PCB28排放速率、栅格规模及与迁移速率相关的参数是影响大气相中PCB28浓度的关键参数.不确定性分析结果表明PCB28在农村大气和城市大气中的浓度分布都符合对数正态分布,其变异系数分别为0.44和0.41.

Fate Simulation of 2,4,4'-Trichlorobiphenyl in the Bohai Rim Using the Multimedia Model

To study the multimedia transfer and fate of polychlorinated biphenyls (PCBs) in the Bohai Rim, we used the BETR-Urban-Rural model to simulate and calculate the concentration distribution, fate distribution, and transfer processes of 2,4,4''-trichlorobiphenyl (PCB28) in nine environmental compartments under a steady-state assumption. The input parameters and output results of the model underwent sensitivity analysis and uncertainty analysis, respectively. The results showed that the simulated concentrations of PCB28 in fresh water, rural soil, urban soil, and sediment could fit the measured concentrations well, thus verifying the reliability of the model. The concentration of PCB28 in urban soil was the highest, and the average concentration was 5.26×10^-6 mol·m^-3. In contrast, the concentration of PCB28 in rural air was the lowest, and the average concentration was 5.79×10^-14 mol·m^-3. When the environmental system reached equilibrium, the largest sink of PCB28 in the Bohai Rim was soil, accounting for approximately 96.45% of the total amount remaining in the system. The mutual transfer processes between air and other environmental compartments were the dominant pathways for PCB28 inter-media transport in the Bohai Rim. Most PCB28 entering the Bohai Sea was transferred by airflow, and the fluxes from rural air to coastal water accounted for approximately 97.22% of the total fluxes of PCB28 entering the sea. According to the result of sensitivity analysis, the emission rates, grid dimensions, and transport velocity were the key parameters affecting the model output. Uncertainty analysis showed that the distributions of PCB28 concentrations in rural air and urban air fitted well with lognormal distributions, and the coefficients of variances (CVs) were 0.44 and 0.41, respectively.