-
气溶胶颗粒物作为大气的重要组分,对气候演化和环境变化等方面有着重要影响. 大气颗粒物的散射效应使到达地球表面的太阳辐射减少,其降温效应可以部分抵消人类排放的温室气体所导致的全球变暖[1]. 气溶胶颗粒物可以成为云凝结核,进而影响到云和降水的物理过程[2]. 研究表明,三极地区对大气气溶胶的变化更为敏感[3]. 大气颗粒物沉降在青藏高原冰雪表面,促进冰雪的消融[4-5]. 青藏高原上黑碳(BC)和沙尘导致反射率降低约38%,造成的总辐射强迫约为18—32 W·m-2[6]. 高原南部扎当冰川上,BC和沙尘对老雪融化的贡献约为9%[7]. 藏东南冰川变化的研究表明,吸光性颗粒物对冰川融化的贡献为15%[8]. 数值模拟实验表明季风前期青藏高原南坡堆积的吸收性气溶胶加热大气形成热泵效应,导致雨季的提前和南亚夏季风的加剧[9]. Cong等发现珠峰北坡气溶胶中二羧酸与生物质燃烧指示物左旋葡聚糖和K+存在明显正相关关系,表明南亚的碳质气溶胶可以通过大尺度环流和局地山谷环流传输到青藏高原[10],大气观测、冰雪冰芯样品和模式模拟显示BC、重金属如汞、有机污染物POPs和微塑料能够跨境传输到青藏高原内部并对环境产生影响[11-14]. 南亚大气棕色云使低层大气变暖的程度和大气气溶胶相同,两者可以使气温在10年内增加0.25 K[15].
青藏高原北邻塔克拉玛干沙漠,西南部是塔尔沙漠,这些地区是青藏高原粉尘的潜在源区. 青藏高原东邻我国人口集中的地区,南邻南亚发展中国家,人为气溶胶也对青藏高原造成了影响. 目前对青藏高原大气颗粒物的研究主要有以下几种手段:1)对冰川区的冰雪及冰芯进行采样,分析微粒物化特征[16-18];2)利用卫星遥感等手段对大气气溶胶光学特征进行监测[19-20];3)直接采集大气气溶胶样品和定点监测[21-22]. 不同的研究手段有不同的利弊,冰芯记录侧重于过去大气粉尘的研究,通常为长期变化趋势;卫星监测和数据模拟可以在长时间和大尺度获取大气气溶胶浓度、光学性质等的信息,成为区域研究的重要工具[23]. 由于青藏高原复杂的地形和地表非均质反射,使得模拟结果和实地监测结果或多或少有偏差[24-25]. 研究表明MODIS AOD数据在拉萨不具有适用性,在高原东部的应用表明数据精度相对较低[26-27]. Sharma等对喜马拉雅地区气溶胶的模拟数值普遍低于实测值[5].
因此,急需地面观测气溶胶颗粒物数据对卫星监测和数值模拟数据来进行验证和校正. 高原西部大气颗粒物的监测数据较少,阿里地区地面实测数据的增加,给高原大气气溶胶的卫星监测和数据模拟研究提供了支撑和验证数据. 本文在大气颗粒物在线观测数据的基础上,获得阿里站大气颗粒物的浓度水平,进而分析其季节变化的基本特征,并综合运用HYSPLIT模型的聚类分析、潜在源贡献因子分析(PSCF)和浓度权重轨迹分析(CWT)方法,分析各个季节阿里站大气气溶胶的输送路径和可能来源,为青藏高原尤其是其西部地区的大气颗粒物研究提供数据支撑.
青藏高原阿里地区大气颗粒物质量浓度的季节变化特征
Seasonal mass concentration variation and potential source regions of atmospheric particulate matter in Ngari area, Tibet Plateau
-
摘要: 基于2018-12-01至2019-11-30在中国科学院阿里荒漠环境综合观测研究站颗粒物监测仪的数据,获得了大气颗粒物质量浓度及其季节变化特征. 研究结果表明,PM10、PM2.5、PM1在观测期间的日均质量浓度分别为(10.51±8.62) μg·m−3、(4.05±2.36) μg·m−3和(2.47±1.56) μg·m−3,低于青藏高原城市地区. PM2.5、PM10远低于国家规定的颗粒物年平均一级浓度限值(GB 3095—2012),表明阿里地区洁净的大气本底特征. 阿里地区污染源稀少,气象因子成为影响颗粒物浓度变化的重要因素. 尽管阿里地处西风和印度季风的过渡带,西南季风显著影响了阿里站颗粒物浓度变化,季风带来的暖湿气团使季风期颗粒物浓度显著降低;加之边界层高度等气象因素的季节变化,使大气颗粒物浓度呈现明显的季节变化规律,冬季和季风前大于季风期和季风后期. 阿里站处于高寒荒漠环境,大气颗粒物以粗颗粒为主,PM2.5/PM10的平均比值为0.39,与其他地点对比,比值偏低. 聚类分析表明,阿里站主要受偏西气团影响. 潜在源贡献因子分析(PSCF)和浓度权重轨迹分析(CWT)分析结果表明,PM10、PM2.5、PM1主要潜在源区均分布在印度西北部、巴基斯坦北部. 由于监测原理的不同和气象因子的影响,MODIS AOD数据与颗粒物浓度数据在12月、7月和8月差异较大,遥感获取的气溶胶参数需要进一步订正提高在高原的适用性.Abstract: Using a GRIMM Environmental Dust Monitor EDM 365, the temporal variation and PM2.5/PM10 ratio of atmospheric particulate matter concentration at Ngari Station from December 1, 2018 to November 30, 2019 were analyzed . The results showed that during the monitoring period, the average daily concentrations of PM10, PM2.5 and PM1 were (10.51±8.62) μg·m−3, (4.05±2.36) μg·m−3, (2.47±1.56) μg·m−3, respectively, which were lower than those in the urban areas of the Qinghai-Tibet Plateau. PM2.5 and PM10 are much lower than the annual average threshold value of class Ⅰ standard of the ambient air quality standard(GB 3095—2012), indicating the clean atmospheric background characteristics in Ngari. Ngari is located in the transitional zone between westerly winds and Indian monsoon. The southwest monsoon significantly affects the change of particulate matter concentration at Ngari station, and the warm and humid air mass brought by monsoon significantly reduces the particulate matter mass concentration during monsoon. In addition, the seasonal variation of meteorological factors such as boundary layer height makes the mass concentration of PM show obvious seasonal variation, which is higher in winter and pre-monsoon than in monsoon and post-monsoon. Ngari Station is located in alpine desert environment, and atmospheric particles are mainly coarse particles. The average ratio of PM2.5/PM10 is 0.39, which is lower than other sites. The cluster analysis shows that Ngari station is mainly affected by the westerly winds. The results of potential source contribution function (PSCF) and concentration-weight trajectory (CWT) showed that the main potential source regions of PM10、PM2.5、PM1 were located in north-western India and northern Pakistan. Due to the different monitoring principles and the influence of meteorological factors, the MODIS AOD data and in-situ PM data are quite different in December, July and August, and the aerosol parameters obtained by remote sensing need to be further revised to improve their applicability in the plateau.
-
表 1 不同站点颗粒物水平的比较(顺序为北京、拉萨、阿里站、珠峰站、Hyytiala站、JGM站)
Table 1. Comparison of atmospheric particulate mass concentration at different stations
-
[1] IPCC. Climate change 2021: the physical science basis[M]. UK: Cambridge University Press, 2021. [2] TAO W K, CHEN J P, LI Z Q, et al. Impact of aerosols on convective clouds and precipitation [J]. Reviews of Geophysics, 2012, 50(2): RG2001. [3] GARRETT T J, ZHAO C F. Increased Arctic cloud longwave emissivity associated with pollution from mid-latitudes [J]. Nature, 2006, 440(7085): 787-789. doi: 10.1038/nature04636 [4] XU B Q, CAO J J, HANSEN J, et al. Black soot and the survival of Tibetan glaciers [J]. Proceedings of the National Academy of Sciences of the United States of America, 2009, 106(52): 22114-22118. doi: 10.1073/pnas.0910444106 [5] SHARMA A, BHATTACHARYA A, VENKATARAMAN C. Influence of aerosol radiative effects on surface temperature and snow melt in the Himalayan region [J]. The Science of the Total Environment, 2022, 810: 151299. doi: 10.1016/j.scitotenv.2021.151299 [6] ZHANG Y L, KANG S C, SPRENGER M, et al. Black carbon and mineral dust in snow cover on the Tibetan Plateau [J]. The Cryosphere, 2018, 12(2): 413-431. doi: 10.5194/tc-12-413-2018 [7] LI X F, KANG S C, ZHANG G S, et al. Light-absorbing impurities in a southern Tibetan Plateau glacier: Variations and potential impact on snow albedo and radiative forcing [J]. Atmospheric Research, 2018, 200: 77-87. doi: 10.1016/j.atmosres.2017.10.002 [8] ZHANG Y L, KANG S C, CONG Z Y, et al. Light-absorbing impurities enhance glacier albedo reduction in the southeastern Tibetan Plateau [J]. Journal of Geophysical Research:Atmospheres, 2017, 122(13): 6915-6933. doi: 10.1002/2016JD026397 [9] LAU K M, KIM M K, KIM K M. Asian summer monsoon anomalies induced by aerosol direct forcing: The role of the Tibetan Plateau [J]. Climate Dynamics, 2006, 26(7/8): 855-864. [10] CONG Z Y, KAWAMURA K, KANG S C, et al. Penetration of biomass-burning emissions from South Asia through the Himalayas: New insights from atmospheric organic acids [J]. Scientific Reports, 2015, 5: 9580. doi: 10.1038/srep09580 [11] KANG S C, CHEN P F, LI C L, et al. Atmospheric aerosol elements over the inland Tibetan Plateau: Concentration, seasonality, and transport [J]. Aerosol and Air Quality Research, 2016, 16(3): 789-800. doi: 10.4209/aaqr.2015.05.0307 [12] 康世昌, 丛志远, 王小萍, 等. 大气污染物跨境传输及其对青藏高原环境影响 [J]. 科学通报, 2019, 64(27): 2876-2884. doi: 10.1360/TB-2019-0135 KANG S C, CONG Z Y, WANG X P, et al. The transboundary transport of air pollutants and their environmental impacts on Tibetan Plateau [J]. Chinese Science Bulletin, 2019, 64(27): 2876-2884(in Chinese). doi: 10.1360/TB-2019-0135
[13] RAMANATHAN V, RAMANA M V, ROBERTS G, et al. Warming trends in Asia amplified by brown cloud solar absorption [J]. Nature, 2007, 448(7153): 575-578. doi: 10.1038/nature06019 [14] ZHANG Y L, GAO T G, KANG S C, et al. Microplastics in glaciers of the Tibetan Plateau: Evidence for the long-range transport of microplastics [J]. Science of the Total Environment, 2021, 758: 143634. doi: 10.1016/j.scitotenv.2020.143634 [15] 柴磊, 王小萍. 青藏高原持久性有机污染物研究现状与展望 [J]. 地球科学进展, 2022, 37(2): 187-201. doi: 10.11867/j.issn.1001-8166.2021.123 CHAI L, WANG X P. Current knowledge and future prospects regarding persistent organic pollutants over the Tibetan Plateau [J]. Advances in Earth Science, 2022, 37(2): 187-201(in Chinese). doi: 10.11867/j.issn.1001-8166.2021.123
[16] WAKE C P, DIBB J E, MAYEWSKI P A, et al. The chemical composition of aerosols over the Eastern Himalayas and Tibetan Plateau during low dust periods [J]. Atmospheric Environment, 1994, 28(4): 695-704. doi: 10.1016/1352-2310(94)90046-9 [17] SHRESTHA A B, WAKE C P, DIBB J E. Chemical composition of aerosol and snow in the high Himalaya during the summer monsoon season [J]. Atmospheric Environment, 1997, 31(17): 2815-2826. doi: 10.1016/S1352-2310(97)00047-2 [18] WU G J, ZHANG X L, ZHANG C L, et al. Concentration and composition of dust particles in surface snow at Urumqi Glacier No. 1, Eastern Tien Shan [J]. Global and Planetary Change, 2010, 74(1): 34-42. doi: 10.1016/j.gloplacha.2010.07.008 [19] FENG X Y, MAO R, GONG D Y, et al. Increased dust aerosols in the high troposphere over the Tibetan Plateau from 1990s to 2000s [J]. Journal of Geophysical Research:Atmospheres, 2020, 125(13): e2020JD032807. [20] 吴浩, 许潇锋, 杨晓玥, 等. 青藏高原及周边区域沙尘气溶胶三维分布和传输特征 [J]. 环境科学学报, 2020, 40(11): 4081-4091. doi: 10.13671/j.hjkxxb.2020.0139 WU H, XU X F, YANG X Y, et al. Three-dimensional distribution and transport characteristics of dust over Tibetan Plateau and surrounding areas [J]. Acta Scientiae Circumstantiae, 2020, 40(11): 4081-4091(in Chinese). doi: 10.13671/j.hjkxxb.2020.0139
[21] MENG Y, LI R, ZHAO Y L, et al. Chemical characterization and sources of PM2.5 at a high-alpine ecosystem in the Southeast Tibetan Plateau, China [J]. Atmospheric Environment, 2020, 235: 117645. doi: 10.1016/j.atmosenv.2020.117645 [22] 李汉林, 何清, 刘新春, 等. 帕米尔高原东部PM10输送路径及潜在源分析 [J]. 中国环境科学, 2020, 40(11): 4660-4668. doi: 10.3969/j.issn.1000-6923.2020.11.003 LI H L, HE Q, LIU X C, et al. Analysis of transport pathways and potential source regions of PM10 in the eastern Pamirs [J]. China Environmental Science, 2020, 40(11): 4660-4668(in Chinese). doi: 10.3969/j.issn.1000-6923.2020.11.003
[23] CHEN B J, YOU S X, YE Y, et al. An interpretable self-adaptive deep neural network for estimating daily spatially-continuous PM2.5 concentrations across China [J]. Science of the Total Environment, 2021, 768: 144724. doi: 10.1016/j.scitotenv.2020.144724 [24] JI Z M, KANG S C, CONG Z Y, et al. Simulation of carbonaceous aerosols over the Third Pole and adjacent regions: Distribution, transportation, deposition, and climatic effects [J]. Climate Dynamics, 2015, 45(9): 2831-2846. [25] ZHAO C F, YANG Y K, FAN H, et al. Aerosol characteristics and impacts on weather and climate over the Tibetan Plateau [J]. National Science Review, 2020, 7(3): 492-495. doi: 10.1093/nsr/nwz184 [26] YOU Y C, ZHAO T L, XIE Y, et al. Variation of the aerosol optical properties and validation of MODIS AOD products over the eastern edge of the Tibetan Plateau based on ground-based remote sensing in 2017 [J]. Atmospheric Environment, 2020, 223: 117257. doi: 10.1016/j.atmosenv.2019.117257 [27] 陈涛, 罗布, 洛桑曲珍, 等. 拉萨市气溶胶光学厚度研究及MODIS产品检验 [J]. 高原山地气象研究, 2017, 37(4): 53-58. doi: 10.3969/j.issn.1674-2184.2017.04.009 CHEN T, LUOBU, LUOSANGQUZHEN, et al. Analysis of the aerosol optical depth in Lhasa and evaluation of MODIS aerosol product [J]. Plateau and Mountain Meteorology Research, 2017, 37(4): 53-58(in Chinese). doi: 10.3969/j.issn.1674-2184.2017.04.009
[28] XIN Y J, WANG G C, CHEN L. Identification of long-range transport pathways and potential sources of PM10 in Tibetan Plateau uplift area: Case study of Xining, China in 2014 [J]. Aerosol and Air Quality Research, 2016, 16(4): 1044-1054. doi: 10.4209/aaqr.2015.05.0296 [29] WANG Y Q, ZHANG X Y, SUN J Y, et al. Spatial and temporal variations of the concentrations of PM10, PM2.5 and PM1 in China [J]. Atmospheric Chemistry and Physics, 2015, 15(23): 13585-13598. doi: 10.5194/acp-15-13585-2015 [30] CHEN P F, YANG J H, PU T, et al. Spatial and temporal variations of gaseous and particulate pollutants in six sites in Tibet, China, during 2016-2017 [J]. Aerosol and Air Quality Research, 2019, 19(3): 516-527. doi: 10.4209/aaqr.2018.10.0360 [31] LI W J, SHAO L Y, WANG W H, et al. Air quality improvement in response to intensified control strategies in Beijing during 2013-2019 [J]. Science of the Total Environment, 2020, 744: 140776. doi: 10.1016/j.scitotenv.2020.140776 [32] MAENHAUT W, NAVA S, LUCARELLI F, et al. Chemical composition, impact from biomass burning, and mass closure for PM2.5 and PM10 aerosols at Hyytiälä, Finland, in summer 2007 [J]. X-Ray Spectrometry, 2011, 40(3): 168-171. doi: 10.1002/xrs.1302 [33] KAVAN J, DAGSSON-WALDHAUSEROVA P, RENARD J B, et al. Aerosol concentrations in relationship to local atmospheric conditions on James ross island, Antarctica [J]. Frontiers in Earth Science, 2018, 6: 207. doi: 10.3389/feart.2018.00207 [34] DUO B, ZHANG Y C, KONG L D, et al. Individual particle analysis of aerosols collected at Lhasa City in the Tibetan Plateau [J]. Journal of Environmental Sciences, 2015, 29: 165-177. doi: 10.1016/j.jes.2014.07.032 [35] 石洪发. 青藏高原珠峰地区大气颗粒物浓度与粒径分布特征研究[D]. 北京: 中国科学院大学, 2021. SHI H F. Study on the concentration and size distribution characteristics of atmospheric particulate matter in Everest region of Qinghai-Tibet Plateau[D]. Beijing: University of Chinese Academy of Sciences, 2021 (in Chinese).
[36] KESKINEN H M, YLIVINKKA I, HEIKKINEN L, et al. Long-term aerosol mass concentrations in southern Finland: Instrument validation, seasonal variation and trends [J]. Atmospheric Measurement Techniques Discussions, 2020: 1-27. [37] 陈思宇, 王晨, 谢亭亭, 等. 2014年中国大陆地区冷、暖季大气颗粒物的分布特征 [J]. 兰州大学学报(自然科学版), 2018, 54(2): 167-174,183. doi: 10.13885/j.issn.0455-2059.2018.02.005 CHEN S Y, WANG C, XIE T T, et al. Spatial distribution of particulate matter in China’s mainland during cold and warm seasons in 2014 [J]. Journal of Lanzhou University (Natural Sciences), 2018, 54(2): 167-174,183(in Chinese). doi: 10.13885/j.issn.0455-2059.2018.02.005
[38] 李岩瑛, 张红丽, 张强, 等. 西北地区东部季风摆动区大气边界层高度对夏季风活动和季风降水的响应特征 [J]. 干旱区地理, 2020, 43(5): 1169-1178. LI Y Y, ZHANG H L, ZHANG Q, et al. Response characteristics of atmospheric boundary layer height to summer monsoon activity and monsoon precipitation of monsoon swing region in the eastern part of northwest China [J]. Arid Land Geography, 2020, 43(5): 1169-1178(in Chinese).
[39] 耿天召, 童欢欢, 赵旭辉, 等. 江淮地区湿沉降对颗粒物清除能力的影响 [J]. 环境科学研究, 2019, 32(2): 273-283. doi: 10.13198/j.issn.1001-6929.2018.11.04 GENG T Z, TONG H H, ZHAO X H, et al. Effect of wet deposition on the removal efficiency of particulate matter in the Yangtze-Huaihe region [J]. Research of Environmental Sciences, 2019, 32(2): 273-283(in Chinese). doi: 10.13198/j.issn.1001-6929.2018.11.04
[40] DUO B, CUI L L, WANG Z Z, et al. Observations of atmospheric pollutants at Lhasa during 2014-2015: Pollution status and the influence of meteorological factors [J]. Journal of Environmental Sciences, 2018, 63: 28-42. doi: 10.1016/j.jes.2017.03.010 [41] ASHBAUGH L L, MALM W C, SADEH W Z. A residence time probability analysis of sulfur concentrations at grand Canyon National Park [J]. Atmospheric Environment (1967), 1985, 19(8): 1263-1270. doi: 10.1016/0004-6981(85)90256-2 [42] HSU Y K, HOLSEN T M, HOPKE P K. Comparison of hybrid receptor models to locate PCB sources in Chicago [J]. Atmospheric Environment, 2003, 37(4): 545-562. doi: 10.1016/S1352-2310(02)00886-5 [43] 彭艳, 王钊, 李星敏, 等. 近50a西安太阳辐射变化特征及相关影响因子分析 [J]. 干旱区地理, 2012, 35(5): 738-745. PENG Y, WANG Z, LI X M, et al. Variation of surface solar radiation and its impact factors of Xi’an in recent 50 years [J]. Arid Land Geography, 2012, 35(5): 738-745(in Chinese).
[44] 何秀, 邓兆泽, 李成才, 等. MODIS气溶胶光学厚度产品在地面PM10监测方面的应用研究 [J]. 北京大学学报(自然科学版)网络版(预印本), 2009(2): 26-32. HE X, DENG Z Z, LI C C, et al. Application of MODIS AOD in surface PM10 evaluation [J]. Acta Scientiarum Naturalium Universitatis Pekinensis, 2009(2): 26-32(in Chinese).
[45] QIN W M, FANG H J, WANG L C, et al. MODIS high-resolution MAIAC aerosol product: Global validation and analysis [J]. Atmospheric Environment, 2021, 264: 118684. doi: 10.1016/j.atmosenv.2021.118684 [46] 林海峰, 辛金元, 张文煜, 等. 北京市近地层颗粒物浓度与气溶胶光学厚度相关性分析研究 [J]. 环境科学, 2013, 34(3): 826-834. doi: 10.13227/j.hjkx.2013.03.025 LIN H F, XIN J Y, ZHANG W Y, et al. Comparison of atmospheric particulate matter and aerosol optical depth in Beijing city [J]. Environmental Science, 2013, 34(3): 826-834(in Chinese). doi: 10.13227/j.hjkx.2013.03.025