Mineral aerosols from western India: Temporal variability of coarse and fine atmospheric dust and elemental characteristics |
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| Authors: | Ashwini Kumar MM Sarin |
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| Institution: | 1. State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081, China;2. Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA;3. College of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049, China;4. Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites (LRCVES/CMA), National Satellite Meteorological Center, Beijing 100081, China;1. Computational Earth Sciences Group, Centre for Development of Advanced Computing, Pune, Maharashtra 411007, India;2. Space and Atmospheric Sciences Division, Physical Research Laboratory, Ahmedabad 380009, India;3. Biospheric Science Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA;4. Department of Civil Engineering, Indian Institute of Technology, Kanpur 208016, India;1. National Remote Sensing Centre, Indian Space Research Organisation, Hyderabad 500 037, India;2. Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram 695022, India;3. Centre for Atmospheric & Oceanic Sciences, Indian Institute of Science, Bengaluru 560 012, India;4. Divecha Centre for Climate Change, Indian Institute of Science, Bengaluru 560 012, India;5. Indian Space Research Organization Headquarters, Bengaluru 560231, India;1. Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing University of Information Science and Technology, Nanjing 210044, China;2. Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China;3. Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China;4. Atmospheric Environment Institute of Safety and Pollution Control, Jinan University, Guangzhou 510632, China |
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| Abstract: | Size-segregated aerosol samples (PM2.5 and PM10) were collected during Jan–Dec-2007 from a high-altitude site located in a semi-arid region (Mt. Abu, 24.6 °N, 72.7 °E, 1680 m asl) in order to asses the temporal variability in the abundance of atmospheric mineral dust and its elemental composition over western India. The mass concentrations of fine (PM2.5) and coarse (PM10–2.5) mode aerosols varied from 1.6 to 46.1 and 2.3 to 102 μg m?3 respectively over the annual seasonal cycle; with dominant and uniform contribution of mineral dust (60–80%) in the coarse mode relative to large temporal variability (11–75%) observed in the fine mode. The coarse mass fraction shows a characteristic increase with the wind speed during summer months (Mar to Jun); whereas fine aerosol mass and its elemental composition exhibit conspicuous temporal pattern associated with north-easterlies during wintertime (Oct–Feb). The Fe/Al weight ratio in PM2.5 ranges from 0.5 to 1.0 during winter months. The relative enrichment of Fe in fine mode, compared to the crustal ratio of 0.44, is attributed to the down-wind advective transport of combustion products derived from large-scale biomass burning, industrial and automobile emission sources located in the Indo-Gangetic Plain (northern India). In contrast, Ca/Al and Mg/Al weight ratios show relative enrichment of Ca and Mg in the coarse mode; indicating their dominant contribution from carbonate minerals. This has implication to efficient neutralization of atmospheric acidic species (SO42? and NO3?) by mineral dust over western India. |
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