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

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 × 106 km2. 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°N, 73.0243°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 (μg gm−1/wt%), respectively. Average δ13C, δ15N, δ34S values of surface soils were − 10.5‰ ± 4.0, 11.4‰ ± 1.6 and 3.6‰ ± 2.1, while δ13C and δ15N of atmospheric PM10 particles varied in ranges − 25.6‰ ± 0.67 and 9.9‰ ± 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

Delineating sources of groundwater recharge and carbon in Holocene aquifers of the central Gangetic basin using stable isotopic signatures

Stable isotopes of water (delta H-2, delta O-18) and delta C-13(TIC) were used as a tool to trace the recharge processes, natural carbon (organic and inorganic) source and dynamics in the aquifers of the central Gangetic basin, India. Stable isotope (delta H-2, delta O-18) record of groundwater (n = 105) revealed that the groundwater of Piedmont was recharged by meteoric origin before evaporation, while aquifers of the older and younger alluvium were recharged by water that had undergone evaporation loss. River Ganges and its tributaries passing through this area have very little contribution in recharging while ponds play no role in the recharging of adjacent aquifers. The connectivity of shallow aquifers of aquitard formation (comprised of clay/sandy clay with thin patches of fine grey sand), i.e. 25-60 m below ground level (bgl) with the main upper aquifer (at a depth of >120 m bgl) was found to be higher in older and younger alluvium. Negative values of delta C-13(TIC) (median -9.6 parts per thousand; range -13.2 to -5.4 parts per thousand) and high TIC (median 35 mM; range 31-46 mM) coupled with low TOC (median 1.35 mg/L; range 0.99-1.77 mg/L) indicated acceleration in microbial activity in the younger alluvium, especially in the active floodplain of river Ganges and its proximity

8000-year monsoonal record from Himalaya revealing reinforcement of tropical and global climate systems since mid-Holocene

We provide the first continuous Indian Summer Monsoon (ISM) climate record for the higher Himalayas (Kedarnath, India) by analyzing a C-14-dated peat sequence covering the last similar to 8000 years, with similar to 50 years temporal resolution. The ISM variability inferred using various proxies reveal striking similarity with the Greenland ice core (GISP2) temperature record and rapid denitrification changes recorded in the sediments off Peru. The Kedarnath record provides compelling evidence for a reorganization of the global climate system taking place at similar to 5.5 ka BP possibly after sea level stabilization and the advent of inter-annual climate variability governed by the modern ENSO phenomenon. The ISM record also captures warm-wet and cold-dry conditions during the Medieval Climate Anomaly and Little Ice Age, respectively

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

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

Depth dynamics of soil N contents and natural abundances of N-15 after 43 years of long-term fertilization and liming in sub-tropical Alfisol

The aim of this study was to understand impacts of long-term (43years) fertilization on soil aggregation, N accumulation rates and N-15 in surface and deep layers in an Alfisol. Soil samples from seven treatments were analysed for N stocks, aggregate-associated N in 0-30 cm and the changes in N-15 in 0-90 cm depths. The treatments were: unfertilized control (control); recommended N dose (N); recommended N and phosphorus doses (NP); recommended N, P and potassium doses (NPK); 150% of recommended N, P and K doses (150% NPK); NPK + 10Mg FYM ha(-1) (NPK + FYM) and NPK + 0.4Mg lime ha(-1) (NPK + L). Results revealed that plots under NPK + FYM had similar to 39% higher total N concentrations than NPK + L in 0-30 cm soil layers. In NPK + L, macro-aggregates had 35 and 11% and microaggregates had 20 and 9% lower N-15 values than NPK + FYM in 0-15 and 15-30 cm soil layers, respectively. However, plots receiving NPK + FYM had similar to 39% greater deep soil (30-90 cm) N accumulation than NPK + L. These results would help understanding N supplying capacity by long-term fertilization and assist devising N management strategies in sub-tropical acidic Alfisols