新疆博斯腾湖多环芳烃污染特征及来源解析研究

As the largest Inland freshwater lake in China, the Bosten Lake has been experiencing the serve environmental pollution due to the rapid development of industry and agriculture. This project will investigate the pollution characteristics, dry deposition flux, and seasonal difference of 16 polycyclic aromatic hydrocarbons (PAHs) listed by the U.S. Environmental Protection Agency (U.S. EPA) as priority pollutants in the Bosten Lake by collecting the air, and water samples. Based on the updated PAHs emission inventory, the environmental behavior and process, such as atmospheric transport, deposition, and air-water exchange will be studied by using CanMETOP (Canadian Model for Environmental Transport of Organochlorine Pesticides) model, and the results were verified and optimized by using the measured PAHs concentration in the environmental medias. The factors that influencing the environmental behavior and process, including air emission, meteorological conditions, and physicochemical properties of PAHs were studied. The sources of PAHs were investigated by combining the inflow and outflow flux, atmospheric emission inventory separation method, and CanMETOP model. The results will provide considerable insight for evaluating the environmental pollution and protecting the ecosystem of the Bosten Lake.

作为我国最大的内陆淡水湖，新疆博斯腾湖近年来因周边大规模工农业开发活动导致水环境问题日益突出。本项目拟以16种USEPA优先控制的PAHs为目标化合物，以新疆博斯腾湖为研究区域，对大气和水体进行为期一年的观测，研究PAHs在这两种环境介质中的污染特征、干沉积通量、气-水界面交换通量及季节性差异；基于更新的网格化大气排放清单，结合CanMETOP模型定量模拟研究博斯腾湖PAHs大气迁移、沉降、气-水交换等环境行为和过程的动态趋势，以一年大气、水体监测数据对清单及模型进行验证和优化；明确影响这些环境行为和过程的大气源排放、气象条件及PAHs物理化学性质等主控因子；计算地表径流PAHs出、入湖通量，结合大气排放清单分离模拟方法，采用CanMETOP模型定量模拟研究导致博斯腾湖PAHs污染的主要来源，为有关决策部门评估博斯腾湖环境污染，保护其生态系统提供科学依据和对策。

该项目以16 种USEPA 优先控制的PAHs 为目标化合物，以新疆博斯腾湖为研究区域，通过采集大气、水体和底泥样品，研究博斯腾湖PAHs 的污染特征、干沉积通量、气-水界面交换及其季节性差异；基于PAHs 网格化大气排放清单，采用CanMETOP 模型定量模拟研究博斯腾湖PAHs大气迁移、干沉积通量、气-水交换方向和交换通量的动态趋势；结合PAHs特征比值、后向轨迹分析和CanMETOP对PAHs环境行为模拟结果，探明博斯腾湖PAHs污染的主要来源，为有关决策部门保护博斯腾湖生态系统提供科学依据和对策。主要研究结果如下：.（1）博斯腾湖流域采暖期和非采暖期PAHs大气浓度范围分别为6.4-245.4和2.3-74.8 ng·m-3，大气干沉降通量范围分别为0.5-18.1和0.3-8.2 μg·m-2·d-1；大气和干沉积中PAHs组成均以3-4环为主；空间分布呈现出居民区>湖泊周边>塔中的空间分布。.（2）湖区表层水中PAHs总浓度范围为51.1-217.2 ng·L-1，PAHs的组成主要以3环和4环为主；表层沉积物样品中PAHs浓度范围为57.4-360.2 ng·g-1（干重），上游河流表层沉积物中PAHs以2-3环为主，湖泊底泥中PAHs以4-6环为主；空间分布呈现出上游高于博斯腾湖区，且湖区污染主要集中在湖心处；沉积柱样品中PAHs浓度范围为31.4-211.9 ng·g-1，沉积速率为0.18 cm·y-1，PAHs组成以5环和6环为主，沉积时间跨度为1852-2016年，PAHs浓度峰值出现在1994年。.（3）数值模拟结果表明，博斯腾湖地区春、夏、秋、冬四个季节PHE干沉积通量分别为134.4、107.8、251.7和264.9 ng·m-2·d-1，BaP干沉积通量分别为1.8、1.9、2.0和3.2 ng·m-2·d-1；而12个月期间，PHE的气-水交换通量为1597.6-4695 ng·m-2·d-1，BaP的气-水交换通量为113.3-238.6 ng·m-2·d-1。.（4）比值法源解析结果表明，博斯腾湖流域大气和干沉降中PAHs主要来源于煤炭和生物质燃烧；CanMETOP模拟和HYSPLIT前向和后向轨迹模拟结果表明，居民区较高PAHs排放通过大气传输到达博斯腾湖区，经大气干沉降和气-水交换进入水体，对博斯腾湖水生环境造成影响。