Seasonality of carbonaceous aerosol composition and light absorption properties in Karachi,Pakistan  

作　　者：Pengfei Chen Shichang Kang Chaman Gul Lekhendra Tripathee Xiaoxiang Wang Zhaofu Hu Chaoliu Li Tao Pu 

机构地区：[1]State Key Laboratory of Cryospheric Science,Northwest Institute of Eco-Environment and Resources(CAS),Lanzhou 730000,China,Chinese Academy of Sciences [2]CAS Center for Excellence in Tibetan Plateau Earth Sciences,Beijing 100101,China [3]Key Laboratory of Tibetan Environment Changes and Land Surface Processes,Institute of Tibetan Plateau Research,CAS,Beijing 100101,China [4]Reading Academy,Nanjing University of Information Science and Technology,Nanjing,Jiangsu,210044,China

出　　处：《Journal of Environmental Sciences》2020年第4期286-296,共11页环境科学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.41705132,41630754);the second Tibetan Plateau Scientific Expedition and Research Program(STEP)(No.2019QZKK0605);Pan-Third Pole Environment Study for a Green Silk Road(Pan-TPE)(No.XDA20040501);Frontier Science Key Project of CAS(No.QYZDJ-SSW-DQC039);CAS“Light of West China”program and the State Key Laboratory of Cryospheric Science(No.SKLCS-OP-2018-01)

摘　　要：Characteristics of carbonaceous aerosol(CA)and its light absorption properties are limited in Karachi,which is one of the most polluted metropolitan cities in South Asia.This study presents a comprehensive measurement of seasonality of CA compositions and mass absorption cross-section(MAC)of elemental carbon(EC)and water-soluble organic carbon(WSOC)in total suspended particles(TSP)collected from February 2015 to March 2017 in the southwest part of Karachi.The average TSP,organic carbon(OC),and EC concentrations were extremely high with values as 391.0±217.0,37.2±28.0,and 8.53±6.97μg/m3,respectively.These components showed clear seasonal variations with high concentrations occurring during fall and winter followed by spring and summer.SO42-,NO3-,K+,and NH4+showed similar variations with CA,implying the significant influence on atmospheric pollutants from anthropogenic activities.Relatively lower OC/EG ratio(4.20±2.50)compared with remote regions further indicates fossil fuel combustion as a primary source of CA.Meanwhile,sea salt and soil dust are important contribution sources for TSP.The average MAC of EC(632 nm)and WSOC(365 nm)were 6.56±2.70 and 0.97±0.37 m2/g,respectively.MACEC is comparable to that in urban areas but lower than that in remote regions,indicating the significant influence of local emissions.MACwsoc showed opposite distribution with EC,further suggesting that OC was significantly affected by local fossil fuel combustion.In addition,dust might be an important factor increasing MACwsoc particularly during spring and summer.

关 键 词：Air pollution Organic carbon Elemental carbon Light absorption Pakistan 

分 类 号：X513[环境科学与工程—环境工程]