Geochemical, stable isotopic, palynological characterization of surface dry soils and atmospheric particles over Jodhpur city (Thar Desert, Rajasthan) during peak summer of 2013

摘要

Atmospheric dust originating from the Thar Desert (India) acts as the local source of mineral dust in South Asia, spreading over an area of 0.32 x 10(6) km(2). Regional studies conducted during peak boreal summer are required to characterize this mineral dust that blows in form of episodic dust storms towards Indo-Gangetic Plains (IGP), using a multi-tracer approach. To achieve this goal, atmospheric PM10 particles were collected along with surface dry soils between 3 and 11 June, 2013, from in and around the Jodhpur city (26.2389 degrees N, 73.0243 degrees E) to glean elemental composition, stable isotopic and palynological (pollen types) database. Typical crustal elemental ratios, e.g. Si/Al, Ca/Al, Fe/Al, K/Al, Mg/Al, Ti/Al, varied in narrow ranges 8.1 +/- 1.21, 1.02 +/- 1.53, 0.50 +/- 0.14, 0.34 +/- 0.06, 0.19 +/- 0.06 and 0.06 +/- 0.02, respectively. Average Sr/Al, Rb/Al and Zr/Al ratios were found to be 39.70 +/- 12.24, 18.00 +/- 2.0 and 70.83 +/- 13.11 (mu g gm(-1)/wt%), respectively. Average delta C-13, delta N-15, delta S-34 values of surface soils were - 10.5 parts per thousand +/- 4.0, 11.4 parts per thousand +/- 1.6 and 3.6 parts per thousand +/- 2.1, while delta C-13 and delta N-15 of atmospheric PM10 particles varied in ranges - 25.6 parts per thousand +/- 0.67 and 9.9 parts per thousand +/- 1.7, respectively. Observed palynoassemblage indicated the open nature of vegetation that usually grows under warm-humid conditions with traces of few allergens and pathogens. Generated chemical-isotopic-pollen database could be utilized for deciphering origin of dust storms in IGP. Detailed multi-proxy characterization of mineral dust from the Thar Desert can further help to determine its role in influencing air quality and human health.