Department of Environmental Chemistry, IDAEA-CSIC, Jordi Girona 18-26, Barcelona 08034, Catalonia, Spain.
Environ Sci Technol. 2011 Jun 1;45(11):4785-92. doi: 10.1021/es200400e. Epub 2011 May 3.
Soils are a major reservoir of persistent organic pollutants, and soil-air partitioning and exchange are key processes controlling the atmospheric concentrations and regional fate of pollutants. Here, we report and discuss the concentrations of polychlorinated biphenyls (PCBs) in soils, their measured fugacities in soil, the soil-air partition coefficients (K(SA)) and soil-air fugacity gradients in rural background areas of N-NE Spain and N-NW England. Four sampling campaigns were carried out to assess seasonal and daily variability and differences between sampling sites. K(SA) values were significantly dependent on soil temperature and soil organic matter quantity, and to a minor extent organic matter type. All the PCB congeners in the soil are close to equilibrium with the atmosphere at rural Ebro sites, but soil fugacities tend to be higher than ambient air fugacities in early and late summer, consistent with the influence of temperature on soil-air partitioning. Therefore, during warm periods, soils increment their strength as secondary sources to the atmosphere. The mixture of PCBs found in the atmosphere is clearly strongly influenced by the mixture of PCBs which escape from soil, with significant correlations between them (R(2) ranging between 0.35 and 0.74 and p-level <0.001 for the Ebro sampling sites). Conversely, the close-to-equilibrium to net sink status of rural UK sites, suggest a close coupling of air and soil concentrations, but it is not possible to elucidate the importance of these soils as secondary sources yet, and presumably there are still significant primary sources to the regional/global environment.
土壤是持久性有机污染物的主要储存库，而土壤-空气分配和交换是控制污染物在大气中的浓度和区域归宿的关键过程。在这里，我们报告并讨论了西班牙东北部和英格兰西北部农村背景地区土壤中多氯联苯（PCBs）的浓度、土壤中测量的逸度、土壤-空气分配系数（K（SA））以及土壤-空气逸度梯度。进行了四次采样活动，以评估季节性和日变化以及采样点之间的差异。K（SA）值与土壤温度和土壤有机质数量密切相关，而与有机质类型的关系较小。土壤中所有的 PCB 同系物在埃布罗农村地区都接近与大气达到平衡，但在夏初和夏末，土壤逸度往往高于环境空气逸度，这与温度对土壤-空气分配的影响一致。因此，在温暖时期，土壤会增强其作为大气二次源的能力。大气中发现的 PCB 混合物显然受到从土壤逸出的 PCB 混合物的强烈影响，它们之间存在显著的相关性（对于埃布罗采样点，R（2）在 0.35 到 0.74 之间，p 值<0.001）。相反，英国农村站点接近平衡到净汇状态，表明空气和土壤浓度密切耦合，但目前还不可能确定这些土壤作为二次源的重要性，可能仍然存在对区域/全球环境的重要的初级源。
