基于化学形态和生物效应的大气颗粒物重金属生态/健康风险评价及其时空分布

Human health risks of inhalable fine particulate matter (PM2.5) and ecological risks of dry deposition (dust fall) are the two significant pollution pathways of airborne heavy metals. However, in the past, they were usually evaluated simply based on the total concentrations of heavy metals in a single spatial-temporal scale, ignoring the differences of chemical speciation and biological responses of heavy metals that are induced by the varied sources and properties of particulate matters. The interactions of different regions are also ignored. Thus in this study, heavy metals in PM2.5 and dust fall in the multi-dimensional urban-suburban-rural transects of a typical city (Nanjing) in the Yangtze River Delta (YRD) of China will be monitored long term, where regional air pollution is anespecially hot environmental issue currently. The cutting-edge technology and pioneered methods will be integrated for airborne metal analysis, including microstructure mineralogy (SEM/TEM-EDX, XRD), source apportionment (PCA-MLR, Pb isotopes, HYSPLIT trajectory clustering), speciation analysis (chemical leaching, EXAFS/XANES), bioavailability tests (simulated lung fluid, diffusive gradients in thin films), and toxicology (human lung cells exposure). Finally, the spatial-temporal distribution patterns of integrated features of concentration/flux, sources, speciation, bioavailability, biological responses, ecological and health risks will be revealed, and its urbanization-meteorological interaction mechanisms will be clarified. The key factors that determine the environmental risks of atmospheric particulates will be identified. The results of the project will improve the theories of environmental pollution process and risk assessments of airborne heavy metals, and also provide the scientific basis for decision-making of local-regional air pollution control and urbanization-economic-environmental sustainable developments.

PM2.5（细颗粒物）的健康危害和降尘（干沉降）的生态风险是大气重金属环境污染的重要表现形式，但以往常基于单一时空尺度的重金属总量进行评价，忽视了颗粒物来源/性质差异导致的重金属化学形态和生物效应的时空变化。本项目综合微观形貌矿物学（SEM/TEM-EDX、XRD）、来源解析（PCA-MLR统计、Pb同位素、气流轨迹聚类）、形态分析（化学浸提、EXAFS）、环境/生物有效性（酸雨溶出、模拟肺液、DGT）、毒理学（人肺细胞暴露）、风险评价模型的前沿技术和首创方法，长期多点监测研究长三角典型城市南京的城市化地理梯度及主导风向下代表性功能区PM2.5和降尘的重金属污染，揭示其浓度通量、形态、有效性、生物响应等综合特征的时空分布规律，阐明其来源的影响机制,提出更科学的生态/健康风险评价方法，判定导致环境危害的关键污染元素及其权重。从而完善重金属污染的环境风险评价理论，为区域大气污染防治决策提供科学依据。

鉴于空气污染特别是大气颗粒物及其重金属污染对人民健康（PM2.5）和生态环境（降尘）的严重威胁，本项目以长三角典型区域的江苏省为例，探讨了城市环境空气质量不同尺度的时间-空间分布特征及其地理、气象和来源等因素影响；重点围绕代表性城市南京市典型空气污染物PM2.5及其重金属成分特征，开展了城市化地理梯度下（工业区-市区-郊区-农村transect）多点长期（2014-2018年）监测采样，通过颗粒物理化分析、来源解析、重金属生物有效性评价（模拟肺液、DGT技术）、组分分离-A549人肺细胞毒性测试、人体健康风险评估等方法手段，综合揭示PM2.5重金属浓度和来源的市域尺度时空分布特征及其影响因素，初步探明过渡金属、水溶性离子、多环芳烃等具体颗粒物成分对PM2.5细胞毒性的贡献，并基于人体有效性合理评估大气颗粒物重金属污染的健康风险；此外，开展了实际降尘监测和大气降尘模拟植物试验，揭示大气降尘对土壤重金属污染、园林植物叶片生理及农作物生长和品质安全影响等生态风险；为区域大气污染防治决策提供科学依据。已发表学术期刊论文12篇，其中SCI论文8篇。