Long Range Transport and Wet Deposition Fluxes of Major Chemical Species in Snow at Gulmarg in North Western Himalayas (India)

Bablu Kumar,Farooq Ahmad Lone,Sudha Singh,Umesh Chandra Kulshrestha,Gyan Prakash Gupta

doi:10.4209/aaqr.2015.01.0056

Abstract

ABSTRACTThe study reports snow chemistry and long range transport of pollutants at Gulmarg in north-western Himalayan region of India during winters of 2012–2013. The pH of snowmelt varied between 5.16 and 7.68 with an average of 5.90. The frequency distribution of pH of snowmelt showed that the maximum number of samples (31%) had pH between 6.81 and 7.20. However, 12% samples were observed to be acidic (below 5.6). Scavenging ratios (SR) values suggested that crustal components (Ca2+, Mg2+) are efficiently removed by snow. The study site has significant influence of non-marine sources. Wet deposition contributed 34, 27, 45, 71, 8 and 13 meq m–2 fluxes of nssSO42–, NO3–, NH4+, nssCa2+, nssMg2+ and nssK+ respectively. Both local emissions as well as long range transport (LRT) of pollutants were found to be the sources of these ionic species. Backward airmass trajectory calculations showed that this site received airmasses from six major sectors i.e., i) North Atlantic Ocean origin (NAO), ii) African origin (Af), iii) Middle East origin (ME), iv) European origin (Eu), v) Western India origin (InW), vi) Pakistan origin (Pk). The highest average pH (7.58) of the snowfall was noticed during InW airmasses which had the lowest ratios of nssSO42–/nssCa2+ and NO3–/nssCa2+. Very high pH has been observed in precipitation samples at Indian sites due to buffering of acidic components by atmospheric dust rich in CaCO3. The lowest pH (4.94) was noticed for ME airmasses which had the highest nssSO42–/nssCa2+ and NO3–/nssCa2+ ratios. Data of present study was compared with a study reported almost three decades ago. We noticed a drastic increase in the concentrations of anthropogenic components such as nssSO42– (114%), NO3– (109%) and NH4+ (90%). This is probably due to increase in LRT of pollutants as well as local activities during past three decades.

Highlights

Rapid urbanization and industrialization processes during past few decades have led to global concern about various processes such as acid deposition, climate change, and monsoon modification etc. (Andreae and Crutzen, 1997; IPCC, 2014)
Backward airmass trajectory calculations showed that this site received airmasses from six major sectors i.e., i) North Atlantic Ocean origin (NAO), ii) African origin (Af), iii) Middle East origin (ME), iv) European origin (Eu), v) Western India origin (InW), vi) Pakistan origin (Pk)
PH of precipitation is affected by other anions especially sources of acidic species

Summary

Introduction

Rapid urbanization and industrialization processes during past few decades have led to global concern about various processes such as acid deposition, climate change, and monsoon modification etc. (Andreae and Crutzen, 1997; IPCC, 2014). Increasing emissions of aerosols are going to affect air quality further affecting global and regional atmospheric phenomenon (IPCC, 2014). Deposition of such anthropogenic constituents via wet and dry removal processes has significant adverse impacts on terrestrial and aquatic ecosystems (Seinfeld and Pandis, 2006). Acid deposition has been a serious problem in North America, Europe and Japan (Hara and Akimoto, 1993; Galloway, 1995; Menz and Seip, 2004) It causes loss of fish populations, loss of soil nutrients, activation of few heavy elements, modification in microbial community structure and changes in forest ecosystem (Brimblecombe et al, 2007). There have been a number of studies on snow chemistry too (Valsecchi et al, 1999; Kang et al, 2004; Marinoni et al, 2005; Kulshrestha and Kumar, 2014)

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