Center for Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Center for Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Total Environ. 2021 Jul 15;778:145810. doi: 10.1016/j.scitotenv.2021.145810. Epub 2021 Mar 3.
Atmospheric lead (Pb) pollution has adverse health effects on humans, while the sources and atmospheric process of Pb are key scientific problems. In this study, the concentrations and isotopic composition of Pb in fine particulate matter (PM), coal and street dust samples collected from a typical megacity Beijing were analyzed to identify the sources of atmospheric Pb. Results showed that the Pb concentrations in PM were high in winter (168.1 ± 32.0 ng/m) and low in summer (27.7 ± 9.1 ng/m), whereas Pb isotopic values presented opposite variation trends. The abnormally elevated Pb concentrations in winter were probably related to coal combustion, while declined Pb concentration in summer may be attributed to favorable meteorological parameters such as high temperature, high wind speed, and frequent rain events. Pb isotopic ratios indicated that anthropogenic sources (coal combustion and vehicle exhaust) and natural sources were the main contributors to Pb in PM. Combined with the binary model, the anthropogenic sources predominantly contributed to Pb in the Beijing atmosphere by approximately 85% annually, while the natural sources accounted for the rest of 15%. More specifically, the contribution of natural sources was about 9.4% in spring, 29.7% in summer, 16.0% in autumn and 6.1% in winter, suggesting that natural sources might contribute more lead into the atmosphere during clear days. Furthermore, the contribution of the vehicle exhaust to atmospheric Pb was nonnegligible in megacity, highlighting that the ownership of motor vehicles in megacity should be regulated and more efforts should be paid to strengthen vehicle emission standard. This study may enrich the reservoir of Pb isotopic composition in nature and provides a new method to investigate the Pb migration and transformation in the environment, and also serve as a theoretical reference for pollution control measures.
大气铅（Pb）污染对人类健康有不良影响，而 Pb 的来源和大气过程是关键的科学问题。本研究分析了北京市典型特大城市采集的细颗粒物（PM）、煤和街道灰尘样品中 Pb 的浓度和同位素组成，以确定大气 Pb 的来源。结果表明，PM 中的 Pb 浓度在冬季（168.1 ± 32.0 ng/m）较高，在夏季（27.7 ± 9.1 ng/m）较低，而 Pb 同位素值则呈现相反的变化趋势。冬季 Pb 浓度异常升高可能与煤炭燃烧有关，而夏季 Pb 浓度下降可能归因于有利的气象参数，如高温、高风速和频繁的降雨事件。Pb 同位素比值表明，人为源（煤炭燃烧和机动车尾气）和自然源是 PM 中 Pb 的主要来源。结合二元模型，人为源对北京大气 Pb 的贡献约为 85%，而自然源贡献其余的 15%。更具体地说，自然源在春季的贡献约为 9.4%，夏季为 29.7%，秋季为 16.0%，冬季为 6.1%，表明在晴朗天气下，自然源可能会将更多的 Pb 排放到大气中。此外，机动车尾气对大气 Pb 的贡献在特大城市中不可忽视，这突出表明特大城市的机动车保有量应加以调控，并应加大力度加强车辆排放标准。本研究可为自然环境中 Pb 同位素组成的研究提供更多信息，并为研究 Pb 在环境中的迁移和转化提供新方法，也可为污染控制措施提供理论参考。
