State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China.
State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China; Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
Environ Pollut. 2019 Oct;253:49-60. doi: 10.1016/j.envpol.2019.06.112. Epub 2019 Jul 5.
Carbonaceous aerosols (CAs) scatter and absorb incident solar radiation in the atmosphere, thereby influencing the regional climate and hydrological cycle, particularly in the Third Pole (TP). Here, we present the characteristics of CAs at 19 observation stations from the Atmospheric Pollution and Cryospheric Change network to obtain a deep understanding of pollutant status in the TP. The organic carbon (OC) and elemental carbon (EC) concentrations decreased noticeably inwards from outside to inland of the TP, consistent with their emission load and also affected by transport process and meteorological condition. Urban areas, such as Kathmandu, Karachi, and Mardan, exhibited extremely high OC and EC concentrations, with low and high values occurring in the monsoon and non-monsoon seasons, respectively. However, remote regions inland the TP (e.g., Nam Co and Ngari) demonstrated much lower OC and EC concentrations. Different seasonal variations were observed between the southern and northern parts of the TP, suggesting differences in the patterns of pollutant sources and in distance from the sources between the two regions. In addition to the influence of long-range transported pollutants from the Indo-Gangetic Plain (IGP), the TP was affected by local emissions (e.g., biomass burning). The OC/EC ratio also suggested that biomass burning was prevalent in the center TP, whereas the marginal sites (e.g., Jomsom, Dhunche, and Laohugou) were affected by fossil fuel combustion from the up-wind regions. The mass absorption cross-section of EC (MAC) at 632 nm ranged from 6.56 to 14.7 m g, with an increasing trend from outside to inland of the TP. Urban areas had low MAC values because such regions were mainly affected by local fresh emissions. In addition, large amount of brown carbon can decrease the MAC values in cities of South Asia. Remote sites had high MAC values because of the coating enhancement of aerosols. Influenced by emission, transport process, and weather condition, the CA concentrations and MAC presented decreasing and increasing trends, respectively, from outside to inland of the TP.
碳质气溶胶（CAs）在大气中散射和吸收入射的太阳辐射，从而影响区域气候和水文循环，特别是在第三极（TP）。在这里，我们展示了大气污染与冰冻圈变化网络中 19 个观测站的 CAs 特征，以深入了解 TP 的污染物状况。OC 和 EC 浓度从 TP 的外部到内部明显降低，这与它们的排放负荷一致，也受到传输过程和气象条件的影响。加德满都、卡拉奇和马尔丹等城市地区表现出极高的 OC 和 EC 浓度，季风季和非季风季的浓度分别较低和较高。然而，TP 内陆的偏远地区（例如纳木错和阿里）的 OC 和 EC 浓度则较低。TP 的南部和北部地区观察到不同的季节性变化，表明两个地区的污染物来源模式和与污染源的距离存在差异。除了来自印度恒河平原（IGP）的长距离传输污染物的影响外，TP 还受到当地排放物（如生物质燃烧）的影响。OC/EC 比值也表明，生物质燃烧在 TP 中心地区较为普遍，而边缘站点（如 Jomsom、Dhunche 和 Laohugou）则受到来自上风地区的化石燃料燃烧的影响。EC 在 632nm 处的质量吸收截面（MAC）范围为 6.56 至 14.7m²g⁻¹，从 TP 的外部到内部呈增加趋势。城市地区的 MAC 值较低，因为这些地区主要受到当地新鲜排放物的影响。此外，南亚城市大量的棕色碳会降低 MAC 值。偏远地区的 MAC 值较高，是因为气溶胶的涂层增强。受排放、传输过程和天气条件的影响，CA 浓度和 MAC 分别从 TP 的外部到内部呈现出降低和增加的趋势。
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