北京湿地削减大气PM2.5的生态系统服务流研究

湿地对大气颗粒物的沉降和运移有一定的影响。目前，相关研究多集中在小尺度定量湿地下垫面的颗粒物沉降速度与沉降量以及湿地植物对颗粒物的吸附或阻滞作用。但由于方法的缺失，研究无法在大尺度上定量解释有关湿地对颗粒物的产生、转移、转化和传递过程，这也导致研究结果对政策制定和城市空间规划缺少指导作用。因此，本研究引入了生态系统服务流模型的理论框架，结合颗粒物干沉降与HYSPLIT模型，量化北京市湿地削减PM_2.5服务的物理流量、流动路径以及受益地区。研究结果表明：（1）北京市湿地2015年PM_2.5沉降总量为4240 t，单位面积的平均沉降量为8.27×10^-3 kg/m²；2018年为2610 t，单位面积的平均沉降量为4.46×10^-3 kg/m²；（2）2015年和2018年北京市湿地削减PM_2.5生态系统服务物理流量最高值均出现在冬季，最低值出现在夏季，总体呈现出冬季 > 春季 > 秋季 > 夏季的趋势；（3）2015年和2018年向华北地区迁移的气流轨迹占当季气流轨迹总数的比例最大，京津冀地区与山东省为主要受益区。研究结果既为科学管理湿地资源和实现区域可持续发展提供客观准确的依据，也可为开展湿地生态系统服务流的相关研究奠定一定的基础。

Ecosystem service flows of wetlands blocking atmospheric PM2.5 in Beijing

Wetlands can reduce particle concentration in atmosphere by changing air conditions and remove particles by deposition as well as plant collection. Previous study only focused on small scale to reveal the effect of wetlands in air pollution control on the mechanism level. However, there lacks precisely study to quantify the effect on a large scale which makes the research results hardly support decision making for the governments. Therefore, in the current study, based on the theoretical framework of the ecosystem service flow model, we used the particulate dry sedimentation model and the HYSPLIT model to empirically test the physical flows, flow paths, and benefited areas of Beijing''s wetland reduction of PM_2.5 services. The results show that (1) the total amount of PM_2.5 settlement in Beijing wetlands in 2015 was 4240 t, and the average settlement per unit area was 8.27×10^-3 kg/m²; while in 2018, it was 2610 t and the average settlement per unit area was 4.46×10^-3 kg/m². (2) In 2015 and 2018, the highest value of the physical flow of Beijing''s wetland reduction PM_2.5 ecosystem services appeared in winter, and the lowest value occurred in summer > Spring > Autumn > Summer trend. (3) The airflow trajectories that migrated to north China in 2015 and 2018 accounted for the largest proportion of the total airflow trajectories in the current season, with Beijing-Tianjin-Hebei region and Shandong Province as the main beneficiaries. Finally, it provides an objective and accurate basis for scientific management of wetland resources and the realization of regional sustainable development, and also lays a foundation for the related research on ecosystem service flows.