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Wildfire is an integral component of the terrestrial ecosystem that plays a significant role in regulating the vegetation cover. The paleofire records stored in lacustrine, peat, or marine sedimentary deposits along with environmental proxy records provide temporal information on fire activity and contemporary climatic conditions on a regional scale. A ~2.8m long peat sedimentary profile from Stagmo, Indus Valley, Ladakh Himalaya was examined for sedimentology and charcoal microfossil contents to investigate fire characteristics and reconstruct wildfires which are compared with paleoclimatic changes and past human activities to assess their significance in biomass burning. Charcoal count (CC) analysis provides a suitable method for investigating climatic and vegetation changes with human intervention when no direct evidence is available in the Late-Holocene Trans Himalaya records. The results bring new insight into the interaction between vegetation, fire, and human activity in the Ladakh Himalaya during the past ~2.8 cal kyr BP. An event characterized by high CC at ~2.8 cal kyr BP is distinct from the whole sequence and cannot easily be explained as only the result of a climatic event. This first high charcoal count phase (2.81–2.55 cal kyr BP) could be a natural response to the expansion of forest and dense vegetation with human management interruption. This paleo wildfire event likely corresponds with the time of the Tibetan Plateau’s immediate human occupation. In the second phase, a relatively low charcoal count (1.65–1.54 cal kyr BP) is supported by the high fuel availability during a transitional phase. The third phase of wildfire reconstruction in Ladakh Himalaya is identified at ~1.38 cal kyr BP. This phase can be correlated with the intensified Indian Summer Monsoon (ISM) advancing to Trans-Himalaya leading to increased human settlement in the region.

Megalithic cultures of central India provide important links between the southern Neolithic-Chalcolithic cultures and the early Historical period (∼500 BC to ∼AD 700) and reveal knowledge of ancient traditions of early inhabitants. Scientific dating of these Megalithic burial sites is a challenging task due to scarcity of dateable material and alterations. Here, we present multiple accelerator mass spectrometry radiocarbon (AMS 14C) dates from equine tooth-enamel and organic food remains recovered from pots from Megalithic burials of the Vidarbha region. Using δ13CTOC and δ15N values of organic food remains recovered from pots, we deduced past-diet (palaeo-vegetation) that indicates C4 type of vegetation and thus arid climate during life-spans of these burials. We also analyzed stable δ13C and δ18O isotopes of equine tooth-enamel to investigate hydro-climatic conditions of Maharashtra (Vidarbha region). A total of 10 AMS 14C dates of tooth enamel provide a time range of AD 250–874 for two Megalithic burials. Two AMS 14C dates of organic food remains recovered from pots corroborated aforementioned time-range. The average δ13C and δ18O of equine tooth-enamel samples were −5.3 ± 2.1‰ and −2.9 ± 0.8‰, respectively, both significantly enriched compared to their modern counterparts (−13.7‰ ± 0.7 and −4.3‰ ± 1.1), indicating intense arid conditions in the past.

Modern feces samples of the endangered red panda (Ailurus fulgens) were examined using multiproxy analysis to characterize the dietary patterns in their natural habitat in India. An abundance of Bambusoideae phytoliths and leaves (macrobotanical remains) provide direct evidence of their primary dietary plants. In contrast, Bambusoideae pollen is sporadic or absent in the pollen assemblages. An abundance of Lepisorus spores and its leaves along with broadleaved taxa, Betula, Engelhardtia, and Quercus are indicative of other important food sources. Average δ13C values (− 29.6‰) of the red panda feces indicate typical C3 type of plants as the primary food source, while the, δ15N values vary in narrow range (3.3–5.1‰) but conspicuously reveal a seasonal difference in values most likely due to differing metabolic activities in summer and winter. The multiproxy data can provide a baseline for the reconstruction of the palaeodietary and palaeoecology of extinct herbivores at both regional and global scales.

The Indus River, originating from Manasarovar Lake in Tibet, runs along the Indus Tsangpo suture zone in Ladakh which separates the Tethyan Himalaya in the south from the Karakoram zone to the north. Due to the barriers created by the Pir-Panjal ranges and the High Himalaya, Ladakh is located in a rain shadow zone of the Indian summer monsoon (ISM) making it a high-altitude desert. Occasional catastrophic hydrological events are known to endanger lives and properties of people residing there. Evidence of such events in the recent geologic past that are larger in magnitude than modern occurrences is preserved along the channels. Detailed investigation of these archives is imperative to expand our knowledge of extreme floods that rarely occur on the human timescale. Understanding the frequency, distribution, and forcing mechanisms of past extreme floods of this region is crucial to examine whether the causal agents are regional, global, or both on long timescales. We studied the Holocene extreme flood history of the Upper Indus catchment in Ladakh using slackwater deposits (SWDs) preserved along the Indus and Zanskar Rivers. SWDs here are composed of stacks of sand-silt couplets deposited rapidly during large flooding events in areas where a sharp reduction of flow velocity is caused by local geomorphic conditions. Each couplet represents a flood, the age of which is constrained using optically stimulated luminescence for sand and accelerator mass spectrometry and liquid scintillation counter 14C for charcoal specks from hearths. The study suggests occurrence of large floods during phases of strengthened ISM when the monsoon penetrated into arid Ladakh. Comparison with flood records of rivers draining other regions of the Himalaya and those influenced by the East Asian summer monsoon (EASM) indicates asynchronicity with the Western Himalaya that confirms the existing anti-phase relationship of the ISM-EASM that occurred in the Holocene. Detrital zircon provenance analysis indicates that sediment transportation along the Zanskar River is more efficient than the main Indus channel during extreme floods. Post–Last Glacial Maximum human migration, during warm and wet climatic conditions, into the arid upper Indus catchment is revealed from hearths found within the SWDs.

A high number industrial hearths, furnaces, and kilns were excavated from an Indus archaeological site 4MSR (western Rajasthan, India) on the dry bed of Ghaggar-Hakra (erstwhile Saraswati) river channel near India-Pakistan international border, providing numerous artifacts of Indus metallurgical activity (jewellery items made of Copper (Cu), Gold (Au) and Silver (Ag), anvil, fishhook, arrowhead, spearhead, moulds, slag etc.). Array of inter-connected hearths, vats, range of stone weights and beads made of semi-precious stones (steatite, terracotta, paste) further suggest the site was being used as a metal-craft factory. Nine 14C ages (seven AMS and two conventional) from cultural layers provided site occupational history spanning from the early Harappan phase to the termination of the mature phase. Maximum number of industrial hearths and furnaces were found during the mature phase (2341 ± 30 to 1691 ± 100 BCE). Highly enriched magnetic susceptibilities (χlf: 114 ± 61.2 × 10−8m3kg−1) in the industrial hearths indicate intense burning activities at these metallurgical factory. Similar enrichments were seen in hearth-sediments for Sulfur (S), Calcium (Ca), Strontium (Sr) and Phosphorous (P) contents. Transition elements viz. Copper (Cu), Zinc (Zn) and Lead (Pb) were significantly enriched in these hearths possibly as major leftovers of the Harappan metallurgical activities. High S contents found in industrial hearths could be due to usage of Sulfur rich material used for metal-works and usage of gypsum for polishing metal ware and floors. Excesses of Calcium (Ca) and Strontium (Sr) could be due to enhanced usage of river-shells used in ornaments and bead making, while elevated Phosphorous (P) contents might be due to presence of charred bones of cattle, tortoise and fish.

The present study aimed at an evaluation of the protoscolicidal potential of methanolic extracts of three herbs; Ferula asafoetida (dried latex), Trachyspermum ammi (fruits) and Hippophae salicifolia (leaves) at three different concentrations (10, 20 and 30 mg/mL) for 20, 40 and 60 minute treatment intervals, with respect to standard allopathic drug albendazole. The in-vitro viability of the protoscolices was assessed by the Eosin exclusion method. The slope of mortality and lethal concentration for 50% (LC50) was determined from the regression graphs of the probit mortality of protoscolices plotted against log values of increasing concentrations of herbal extracts for 60 minute treatment intervals. The percentage of mortality caused by various extracts at concentrations ranging from 10-30 mg/mL varied from 29.54-97.76% with maximum mortality of 97.76, 97.30 and 81.91% recorded with methanolic extracts of F. asafoetida, T. ammi and H. salicifolia, respectively. Among all the extracts, the highest protoscolicidal activity was exhibited by F. asafoetida at 20 and 30 mg/mL concentrations in the 60 (97.16%) and 40/60 minutes (97.20% and 97.76%) treatments, respectively, and it showed a minimum LC50 value of 0.204, followed by T. ammi at 0.933. As compared to the standard allopathic drug, albendazole, the methanolic extracts of F. asafoetida and T. ammi exhibited better or comparable protoscolicidal activities., Cilj je istraživanja bila procjena protoskolicidnog potencijala metanolnih ekstrakata triju biljaka: Ferula asafoetida (sušena smola), Trachyspermum ammi (voće) i Hippophae salicifolia (lišće) u trima različitim koncentracijama (10, 20 i 30 mg/mL) u 20, 40 i 60-minutnim pokusnim intervalima u odnosu na standardni alopatski lijek albendazol. In vitro vitalnost protoskoleksa procijenjena je metodom isključivanja eozina. Krivulja pomora i smrtonosne koncentracije za 50 % (LC50) određena je iz regresijskih grafikona mortaliteta protoskoleksa u odnosu na log vrijednosti rastućih koncentracija biljnih ekstrakata tijekom 60-minutnog intervala. Pomor uzrokovan različitim ekstraktima u koncentracijama od 10 do 30 mg/mL varirao je od 29,54 do 97,76 % s najvišim postotkom od 97,76, 97,30 i 81,91 % u slučaju metanolnih ekstrakata F. asafoetida, T. ammi i H. salicifolia. Od svih primijenjenih ekstrakata najvišu protoskolicidnu aktivnost imala je F. asafoetida u koncentracijama od 20 i 30 mg/mL tijekom tretmana od 60 (97,16 %) i 40/60 minuta (97,20 i 97,76%), te je pokazala minimalnu vrijednost LC50 od 0,204, praćenu s T. ammi od 0,933. Usporedbom sa standardnim antiparazitikom albendazolom, metanolni ekstrakti biljaka F. asafoetida i T. ammi ostvarili su bolji ili slični protoskolicidni učinak.

A chronologically well-constrained sedimentary archive from Upshi (Ladakh) was studied using a multi-proxy approach namely palynology, environmental magnetism, total organic carbon (TOC), total nitrogen (TN), stable isotopes of carbon and nitrogen providing a continuous vegetation, and paleoenvironmental history spanning the last ~2700 years with a temporal resolution of ~43 years. Pollen assemblage shows non-arboreal pollen (NAP) and non-pollen palynomorph (NPP) were dominant around the Upshi from ~2646 to 2431 cal. yr BP, indicating warmer conditions. Arboreal pollen (AP) and NAP gradually increased from 2431 to 1860 cal. yr BP in the study area, under warm and wet conditions, corresponding to the Roman Warm Period (RWP). This phase also witnessed enhanced sediment δ15N and χlf values. From ~1860 to ~1154 cal. yr BP increased Chenopodiaceae/Amaranthaceae and substantial spread of NPP suggest decreased temperature and prevalence of cold-dry climate. This period also records declining trends of χlf, δ15N, δ13Corg, TOC, and TN contents. From ~1154 to 293 cal. yr BP, the vegetation type reversed to mixed conifer and broad-leaved forest with significant increase in herbaceous taxa, rising δ15N, δ13Corg, TOC, and TN suggesting warm and wet conditions in the study area. This period broadly corresponds to the ‘Medieval Warm Period’ (MWP). Among all the proxies employed, depth profiles of TOC and TN (wt%) appear to respond best against external climate forcing showing remarkable correlation(s) with residual Δ14C in atmosphere, indicating dominance of intrinsic solar variability on regional climate/environment. The reconstructed recorded is well connected with established historical events and cultural activities of the Eurasian region.

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.

Rising levels of air-borne suspended particulate matter with aerodynamic diameter ≤ 2.5 μm (PM2.5) in the Asian mega cities is a serious cause of concern. A severe SMOG (smoke+fog) episode with air-visibility of about 5 km or shorter and average PM2.5 concentration of 793 μg m−3 occurred in Delhi and the National Capital Territory (NCT) just after the Diwali-festival and spanned between 30 October (Oct.) and 07 November (Nov.) 2016. Using daily variations in chemical and isotopic signatures of PM2.5 in tandem with meteorological parameters, we deduce here primary contributing factors responsible for development of Delhi-SMOG-2016 event and dominant transformation pathways of carbon, sulphur, and nitrogen compounds. Our multi-tracer analyses revealed there could be three major factors contributing to the SMOG event: (i) transport of carbonaceous material from North-Western India (mainly Punjab-Haryana) due to open-field agricultural-waste burning that rose from 26 Oct. through 11 Nov. 2016, (ii) weaker northerly winds, shallower boundary layer, cooler air temperatures, and enhanced humidity enforcing ‘atypical’ air-stagnation, and (iii) direct emissions from fire-cracker bursting on 30 Oct. 2016 (Diwali night). Investigating timing of agricultural waste burning in northwester states of Delhi, there appears to be a delay in the timing of agricultural-waste burning in the Punjab area since 2010; that could possibly causing a gradual increase in severity of SMOG events in the recent years.

Available results on the evaluation of nitrogen (N) use efficiency in conservation agriculture (CA) are inconsistent and studies that cover all three components of CA are sparse, especially in tropical agro-ecosystems. Hence, CA effects on variations in total soil N (TSN) and aggregate-associated 15N on a sandy loam soil were evaluated after 15N urea (~5% atom excess) application at 120 kg ha−1 to wheat in the fourth year of an experiment in the Indo-Gangetic Plains (IGP). The cropping system during 2008–2011 was cotton (Gossypium hirsutum)-wheat (Triticum aestivum), that was changed to maize (Zea mays)-wheat in 2011–2012. Results revealed that plots under zero tillage with residue retention of both crops (ZT + R) had better topsoil (0–5 cm layer) aggregation and higher residual 15N in soils than conventionally tilled (CT) plots. The ZT + R plots also had higher macro-aggregates (0.25–8 mm) with less silt + clay sized particles than the CT plots in the 5–15 cm soil layer. Furthermore, both tillage and residue management had significant effects on TSN and aggregate-associated N stocks. The plots under ZT + R had ~9% higher TSN in topsoil than the CT plots and the ZT and ZT + R plots had about 48 and 34% higher large macro-aggregate associated N stocks than CT and CT + R plots, respectively. However, the potential N-mineralization data of the macro-aggregates of ZT + R (CA) and CT plots were similar. In addition, the fertilizer 15N use efficiency, the residual fertilizer 15N in soil (0–45 cm layer) and the calculated unaccounted fertilizer 15N data of both CA and CT plots were also similar after the fourth year of cultivation. In summary, although CA (ZT + R) adoption had better soil aggregation and with more TSN accumulation within macro-aggregates, it could not affect the fertilizer 15N use efficiency within a short period (4 years). Thus, with a short-term adoption of CA, fertilizer-N dose may not be reduced in a sandy loam soil of the IGP and similar agro-ecosystems.

The rise of the Himalayas governed the Indian Summer Monsoon in Karewa basin during Plio-Pleistocene. A palynological study is presented to delineate the climate-vegetation relationship using an 8.5-m thick fluvio-lacustrine sequence of the Hirpur Formation (2.4–2.1 Ma). Our results suggest that the sediment sequence is mainly comprised of two units, namely, Unit 1 and Unit 2. Unit 1 shows the dominance of sub-tropical to broad-leaf temperate vegetation when mean annual temperature (MAT) was ~17°C and mean annual precipitation (MAP) was 1025 mm. The subsequent increase in sand followed by a thin lignite layer with Trapa megafossil (fruits) demarcates fluvial adjustments, suggesting a low altitude fluvio-lacustrine ecosystem. Conversely, Unit 2 shows a decline in rainforest pollen with a steady increase in conifers. The abrupt dominance of diatom species Tetracyclus lacustris and related species with MAT and MAP reducing to 10°C and 770 mm reveal a colder climate with the lacustrine ecosystem. This change of tropical to cool temperate vegetation could be attributed to the altitudinal rise of the Pir Panjal Mountains and consequent obstruction of the south-west monsoon, which resulted in lower precipitation and temperature during ~2.4–2.1 Ma. Hence, the relic tropical flora of Palaeogene/Neogene transformed to Himalayan temperate flora sometime ~2.1 Ma.

2,4-Dihydroxyacetophenone benzoylhydrazone (DHABH) collectively has been used for the anticorrosive activity towards soft cast steel and as a complexing agent for formation of a coordination complex with tungsten (VI). The corrosion inhibition properties of the reagent are examined in acidic medium at variable concentrations and temperatures utilizing different techniques like gravimetric and electrochemical including polarization measurements and electrochemical impedance spectroscopy (EIS) and quantum chemical calculations. It has been found from the study that inhibition potency increased with increasing concentration of DHABH as indicated by weight loss measurement, polarization curves and EIS studies. However, the complexation conduct of the reagent with tungsten (VI) to form 1:3; W(VI): DHABH complex is studied spectrophotometrically. The produced method of determination has been observed to be exceedingly sensitive, selective, quick, reproducible and satisfactorily pertinent to a wide variety of technical and synthetic samples.

Micro determination of Zirconium (IV) has been carried out using 3-Hydroxy-2-[2′-(5′-methylthienyl)]-4H-chromen-4-one (HMTC) as an analytical reagent. Zr (IV) forms a 1:4 (M:L) yellow coloured complex with HMTC extracted into dichloromethane from ammoniacal medium (pH 7.05–7.09). The complex system shows a maximum at 424–440 nm and follows Beer’s law in the range 0.0–0.9 µg Zr (IV) ml−1 with an optimum range of determination as 0.27–0.79 µg Zr (IV) ml−1as detected from Ringbom plot. Zr (IV)-HMTC complex has molar absorptivity of 8.22 × 104 Lmol−1 cm−1, specific absorptivity of 0.900 ml g−1 cm−1 and Sandell’s sensitivity value 0.0011 µg Zr (IV)cm−2; the linear regression equation being Y = 0.981X − 0.036 (Y = absorbance, X = µg Zr (IV) ml−1) with the correlation coefficient 0.9987. Detection limit of the procedure is 0.0174 µg ml−1. The repercussions obtained are highly consistent with the standard deviation of ±0.0039 absorbance unit and has been confirmed by student’s t-test with 0.5% limit. The proposed technique has been successfully applied in diverse synthetic and industrial samples.

The capital city of India, New Delhi, is experiencing serious PM

Pollutants transport from South and Southeast Asia can profoundly affect the marine atmospheric boundary layer (MABL) over the Bay of Bengal (BoB). This study presents chemical and stable isotopic composition of PM

Limited information is available on long-term fertilization impacts on soil organic carbon (SOC) sequestration in deep soils and C pools within bulk soils and aggregates. Hence, the major objectives of this study were to evaluate long-term (44 years) fertilization impacts on: (i) soil aggregation, labile and recalcitrant C pools within bulk soils and aggregates and (ii) deep soil C accumulation versus sequestration. Treatments were: no mineral fertilizer or manure (control), 100% recommended dose of nitrogen (N), N and phosphorus (NP), N, P and potassium (NPK), 150% recommended NPK (150% NPK), and NPK + farmyard manure (FYM) (NPK + FYM). Labile C, recalcitrant C, total SOC and glomalin in bulk soils and their aggregates were determined in the 0–15 and 15–30 cm soil layers. In addition, total SOC, labile and recalcitrant C contents were measured in the 30–60 and 60–90 cm soil layers. Results revealed that C accumulation and sequestration in NPK + FYM over control plots were 0.74 and 0.22 Mg C ha−1 yr−1, respectively, in 0–90 cm soil layer with >50% of the accumulated C in deep soil layers (30–90 cm). In 0–15 cm layer, despite NPK + FYM and NPK plots had similar amounts of soil macroaggregates, microaggregates were 27% higher with NPK + FYM than NPK, causing higher aggregate stability. Plots with NPK and NPK + FYM had more labile: recalcitrant C ratios in bulk soils than control, NP and N plots. The NPK + FYM plots also had highest recalcitrant C pools within macro- and microaggregates. Glomalin was generally positively correlated with all labile C pools in both soil layers. Additionally, mean weight diameter (MWD) was positively correlated with aggregate-associated C and glomalin within bulk soils. Overall, NPK + FYM management practice not only had higher C accumulation and sequestration in surface and deep soils, but also had better aggregation and ∼26% greater carbon management index than NPK in soil surface and hence should be adopted.

Traditionally, the atmospheric particle composition is analyzed using destructive methods. In general, the destructive methods lead to the destruction of the samples, higher cost of the analysis and larger analysis time. In view of aforesaid, in current work, we present a method for the non-destructive analysis of atmospheric particles using open path-Fourier transform infrared spectroscopy (OP-FTIR). The developed method has been used for the measurement of ammonium and sulfate in atmospheric particles without destroying the samples. Here, we targeted the said species because of their relative importance for air pollution episode formation. Particulate sulfate plays a major role in formation of haze. However; particulate acidity is an important factor in this process, which is governed by particulate ammonium concentration. Therefore, both SO42− and NH4+ are important as far as atmospheric chemistry of haze formation is concerned. In the present study, the qualitative and quantitative estimation of ammonium and sulfate ions in PM2.5 (particulate matter with aerodynamic diameter less than 2.5 µm) was carried out using OP-FTIR with the developed method. The seasonal average concentration of NH4+ and SO42− were measured to be 12.00 ± 5.80, 31.71 ± 12.71 µg/m3 respectively for winters, 3.00 ± 0.85 and 8.00 ± 2.28 µg/m3 respectively for summers and 2.60 ± 1.90 and 7.00 ± 5.21 µg/m3 respectively for monsoon season. The observed results are found to be in good agreement with that of other studies using destructive methods.

Vadnagar town of western India (North Gujarat) possess continuous human habitation record since ~2500 years. Owing to its rich cultural heritage, the town had been visited by Chinese pilgrims including Hiuen Tsang in 640 CE. Recent archaeological excavations at Vadnagar revealed continuous sequence of seven successive cultures from the Early historic (6th century BCE to 4th century BCE) period till present. From 2017 to 18 excavation seasons, ~18–20 m accumulation of cultural deposits were found at Ambaghat and Darbargarh localities. To complement and fortify the cultural chronology of these ancient cultural deposits, both conventional radiocarbon (C-14) and optically stimulated dating (OSL) methods were employed. Three C-14 and five OSL dates matched perfectly with the cultural ages of deposits and the entire cultural sequence spanned between 2nd century BCE to 6th century CE. Geochemical proxies (δ13C, δ 15N, C/N ratios) of excavated soil-sediments were measured to infer hydro-environmental conditions while soil magnetic parameters (χlf, χhf and χfd%) were measured to assess anthropogenic heating history. Average δ 13CTOC values of both trenches (−20.7 ± 3.5‰, −19.5 ± 3.5‰) indicated drier status of soil-sediments. Soil magnetic susceptibilities at lower and higher frequency ranges (χlf and χhf) varied in overlapping ranges i.e. 88.5 ± 43.1 and 121.4 ± 72.1 (10−8m3 kg−1) respectively, indicating the presence of super paramagnetic grains in the soil attributable to firing activities of soil-sediment. Average χfd% values (8.3 ± 1.1, 7.7 ± 2.0) indicate excavated soils undergone pedogenic processes.

We use paleoflood deposits to reconstruct a record of past floods for the Alaknanda-Mandakini Rivers (Garhwal Himalaya), the Indus River (Ladakh, NW Himalaya) and the Brahmaputra River (NE Himalaya). The deposits are characterized by sand-silt couplets, massive sand beds, and from debris flow sediment. The chronology of paleoflood deposits, established by Optically Stimulated Luminescence (OSL) and C-14 AMS dating techniques, indicates the following: (i) The Alaknanda-Mandakini Rivers experienced large floods during the wet and warm Medieval Climate Anomaly (MCA); (ii) the Indus River experienced at least 14 large floods during the Holocene climatic optimum, when flood discharges were likely an order of magnitude higher than those of modern floods; and (iii) the Brahmaputra River experienced a megaflood between 8 and 6 ka. Magnetic susceptibility of flood sediments indicates that 10 out of 14 floods on the Indus River originated in the catchments draining the Ladakh Batholith, indicating the potential role of glacial lake outbursts (GLOFs) and/or landslide lake outbursts (LLOFs) in compounding flood magnitudes. Pollen recovered from debris flow deposits located in the headwaters of the Mandakini River showed the presence of warmth-loving trees and marshy taxa, thereby corroborating the finding that floods occurred during relatively warm periods. Collectively, our new data indicate that floods in the Himalaya largely occur during warm and wet climatic phases. Further, the evidence supports the notion that the Indian Summer Monsoon front may have penetrated into the Ladakh area during the Holocene climatic optimum. (C) 2016 Elsevier B.V. All rights reserved.

The entire Indo-Himalayan region from northwest (Kashmir) to northeast (Assam) is facing prevalence of floods and landslides in recent years causing massive loss of property, human and animal lives, infrastructure, and eventually threatening tourist activities substantially. Extremely intense rainfall event of 2013 C.E. (between 15 and 17 June) kicked off mammoth flash floods in the Kedarnath area of Uttarakhand state, resulting in huge socioeconomic losses to the state and country. Uttarakhand is an important hilly region attracting thousands of tourists every year owing to numerous shrines and forested mountainous tourist spots. Though recent studies indicate a plausible weakening of Indian summer monsoon rainfall overall, recurrent anomalous high rainfall events over northwest Himalaya (e.g. -2010, 2013, and 2016) point out the need for a thorough reassessment of long-term time series data of regional rainfall and ambient temperatures in order to trace signatures of a shifting pattern in regional meteorology, if any. Accordingly, here we investigate ~ 100-year-long monthly rainfall and air temperature time series data for a selected grid (28.5°N, 31.25°N; 78.75°E, 81.25°E) covering most parts of Uttarakhand state. We also examined temporal variance in interrelationships among regional meteorological data (temperature and precipitation) and key global climate variability indices using advance statistical methods. Major findings are (i) significant increase in pre-monsoon air temperature over Uttarakhand after 1997, (ii) increasing upward trend in June–July rainfall and its relationship with regional May temperatures (iii) monsoonal rainfall (June, July, August, and September; JJAS) showing covariance with interannual variability in Eurasian snow cover (ESC) extent during the month of March, and (iv) enhancing tendency of anomalous high rainfall events during negative phases of Arctic Oscillation. Obtained results indicate that under warming scenario, JJ rainfall (over AS) may further increase with occasional extreme rainfall spells when AO index (March) is negative.

The capital city of India, New Delhi, is experiencing serious PM2.5 pollution in the form of recurrent hazy skies and smoky fog (SMOG) episodes in recent years. Besides source-emission strengths, frequency and time-spans of these air-pollution episodes are uncertain due to variable urban meteorological influences, preventing the formation of a cohesive policy to tackle air-quality degradation. About 70% mass of PM2.5 particle is composed of Carbon (C), Nitrogen (N), and Sulphur (S) and, hence, their mass concentrations along with their stable isotopic imprints (viz. δ13CPM2.5, δ15NPM2.5 and δ34SPM2.5) provide powerful tools to gain insights into complex aerosol chemistry. This study presents the aforementioned data generated for PM2.5 collected from New Delhi covering full post-monsoon, winter, and summer months of 2014–15. Temporal variability in the generated dataset was analyzed with variabilities in atmospheric concentrations of key gaseous species (NH3, NOx, and SO2) and meteorological indices. The highest PM2.5 concentrations were observed in winter months with enhanced aerosol N and S concentrations. Active biomass (crop-residue) burning in the northwest Indo-Gangetic Plains (IGP) appears to be the major source of aerosol TC for post-monsoon and winter months in addition to emission sources from the combustion of bio- and fossil- fuels. Aerosol TN contents appear to be largely impacted by ambient ammonia emissions, especially during winter. Aerosol TS contents could be manifested by emissions from coal combustion, road dust, and biogenic sulphur. Total C + N + S contents of PM2.5 showed significant negative correlations with surface solar radiation and air-visibility. Both δ15NPM2.5 and δ34SPM2.5 values show remarkable correlations with air-quality and meteorological parameters during winter months demonstrating considerable secondary cycling. Cluster analysis and concentrated weighted wind trajectories over New Delhi for the study-period showed ~64% and ~58% of air mass trajectories from the northwest (Punjab-Haryana) region during post-monsoon and winter months respectively.

In this communication we reconstruct climate variability of Ladakh, Trans-Himalaya region, on sub-century timescale spanning the last four millennia (~4130 to 260 cal yr ‘before present’ (BP)). To achieve this objective, we measured a suite of physical, biotic and inorganic proxies of a lacustrine sequence. In general, between ~4130 to ~2640 cal yr BP proxy records reveal climate variability following a typical pattern of the northern hemispheric climate and appear to be dominated by westerlies. Thereafter, the Indian Summer Monsoon (ISM) forcing appears to dominate regional climate. The former period appears to have experienced human presence as evidenced by an invasive species of diatom –Didymosphenia and charcoal, likely originating from human activities on trading routes with Central Asia, China and Tibet. After ~2640 cal yr BP, when ISM started governing the climate of the Ladakh- Karakoram region, it probably induced high-frequency climate variability leading to disasters related to landslides, debris flows, avalanches etc., eventually reducing the intra-boundary trade. A similar situation appears to be gripping the region again as meteorologically recorded precipitation data from Ladakh reveals arrival of high-frequency monsoonal variability in the region with recurrent flash floods (e.g., 2010, 2013).

Simultaneous measurements of stable isotopes of Nitrogen (N), Carbon (C) and Sulfur (S) in a single aliquot of sample using stable isotope mass spectrometry coupled with elemental analyzer (EA) in a continuous flow mode has provided added advantages for stable isotopic data community scientifically as well as economically. For NCS isotopic measurements, certain configurational changes were adapted in the EA setup such as (1) introduction of ‘purge and trap columns’ for adsorbing and desorbing analyte CO2 and SO2, and (2) introduction of in-line ring heater to cover for the entire passage between combustion and reduction reactor to prevent any condensation of analyte gases. These modifications were made to achieve necessary accuracy and precision NCS isotopic measurements. However, the presence of in-line ring heater appears to have an influence on δ15N measurements especially for samples containing lower N amounts (≤2 μmoles). We compared δ15N measurements in both NCS and NC modes by reconfiguring same EA (Vario Pyrocube) connected with Isoprime mass spectrometer with wide range variability in N content. We observed a decreasing pattern in δ15N values with increasing N contents (till the true δ15N value is approached), which is an opposite trend compared to that typically observed with the NC mode of EA setup. We surmise thermal heating of the passage from the combustion and reduction reactors is most likely responsible for the observed pattern. Measured δ15N values for samples containing lower N (≤2 μmoles), however, could be corrected using appropriate correction procedure.

Pollutants transport from South and Southeast Asia can profoundly affect the marine atmospheric boundary layer (MABL) over the Bay of Bengal (BoB). This study presents chemical and stable isotopic composition of PM10 collected at Port Blair Island (11.6°N, 92.7°E) located in the middle of the BoB during the late northeast monsoon (February–April), a period when the BoB receives considerable continental outflow. These samples (n = 50) were analysed for major ions, carbonaceous species, trace metals, and isotopic composition of total C, N, and S components. Mass concentration of PM10 ranged from 24 to 65 μg m−3 during the study period. The dominance of continental inputs over a marine realm was evident by a significant amount of non-sea-salt (nss)-SO42− (range: 1.8 to 16.9 μg m−3), which accounts for ~65% of the total water-soluble inorganic constituents. The impact of anthropogenic emissions was further evident from the widespread depletion of chloride (range: 57–100%, avg.: 98 ± 7%) from sea-salt aerosols. Carbonaceous species (elemental carbon and organic matter) contributed nearly 35% to PM10. Further, average δ13C (−25.6‰ ± 0.5) and δ34S (4.5‰ ± 1.3) values observed over the marine study region were similar to those found in typical urban environments. δ15N values (13.7‰ ± 5.1) show the significant presence of combustion sources along with the effect of atmospheric processing. Aerosol δ13C values correlate positively with the ratio of water-soluble organic carbon to total organic carbon, indicating the aging of organic aerosols during the transport. Chemical and isotopic data suggest that both biomass burning (BB) and fossil fuel burning (FFB) contributed to ambient PM10 with relatively more contribution of BB during February to early March and that of FFB during late March to middle of April. In aggregate, this study provides newer insights into sources of carbonaceous species and their chemical processing in MABL of BoB.

Conventional beta counting technique based radiocarbon dating facility at Birbal Sahni Institute of Palaeosciences- Lucknow was established in 1974 (Rajagopalan,1978). In 2017–18, BSIP received an upgrade with installation of an Automated Graphitization Equipment (AGE) coupled with an Elemental Analyser, a Carbonate Handling System (CHS) along with an in-line stable isotope mass-spectrometer (IRMS). Using this combo, stable Carbon (C), Nitrogen (N) and Sulfur (S) isotopic measurements could be carried out in both organic and inorganic type samples followed by graphite preparation (~1 mg) for 14C measurement by Accelerator Mass Spectrometry (AMS). This communication addresses details of pre-processing, processing, and quality checks adopted for achieving acceptable and demonstrable accuracy and precision of measured Δ14C, δ13C, δ15N, and δ34S measurements. Information regarding chemical preparation of samples for aforesaid stable and radio isotopic analysis is provided in succinct manner. Overall, average coefficient of variation determining precision of our graphite powders for 14C measurements is ~2.4%. The mean age of blank (anthracite) processed using established EA-IRMS-AGE unit comes as 42,100 ± 300 years.

The regional dust morphology and spectral refractive indices (RIs; governed by hematite, Fe2O3 content at short wavelengths) are key elements for ascertaining direct radiative forcing of mineral dust aerosols. To provide morphological features of background mineral dust from a semi-arid zone in the vicinity of the Thar Desert, we carried out an expedition to the Jaipur city during late winter of 2012. Morphological analysis reveals the predominance of “Layered”, “Angular” and “Flattened” particles, while the frequency distribution of a total of 235 dust particles shows the aspect ratio, AR and circularity parameter, CIR (measures of particle’s non-sphericity) typically ~1.4 and ~0.8, respectively. Sensitivity analysis at 550 nm wavelength reveals the equivalent sphere model may underestimate Single Scattering Albedo, SSA for the dust with low (~1.1%) hematite by ~3.5%. Both underestimation (by ~5.6%) and overestimation (up to 9.1%) are probable in case of dust with high hematite content (~5.68%). In addition, the effect of AR on the dust scattering is significant in case of dust with high hematite content. More such regionally representative dust morphological data are required for better estimation of regional radiative forcing of mineral dust aerosols.

We measured stable isotopic and chemical characteristics of bulk aerosols collected at a coastal station in western India (Goa) between December 2009 and January 2011, to characterize lower tropospheric atmospheric conditions and their influence on particle chemistry during winter and summer seasons. Marked differences were observed in terms of sources and chemical compositions of bulk aerosols. The δ 15 NTN values of winter aerosols (10.8 ± 2.2‰, n = 10) indicate biomass burning contributions in the carbonaceous fraction, while significantly depleted δ 15 NTN values of summer aerosols (6.2 ± 2.3‰, n = 12) hints incorporation of marine N species. The δ 34 STS showed depleted values during winter (5.0 ± 1.0‰, n = 10), which closely matched with those of typical urban polluted environments, while summer aerosols showed a systematic enrichment of δ 34 STS (up to ~14‰ with average value 9.0 ± 2.8‰, n = 13); possibly due to incorporation of volatile dimethyl sulfide (DMS) and its precursor dimethylsulfoniopropionate (DMSP) emitted from the adjacent Arabian Sea. Likewise, δ 13 CTOC values showed ~2‰ enrichment in winter aerosols (–24.8 ± 0.4‰, n = 10) with respect to those of summer values, indicating presence of bio-fuel and coal burning contributions in carbonaceous fraction of winter aerosols. We also measured major ions (Na + , K + , Mg ++ , Ca ++ , NH4 + , Cl – , Br – , NO3 – , SO4 –2 ) in water soluble fraction of aerosols to understand winter/summer changes in the atmospheric chemistry over this coastal area. This is the first ever dataset on triple isotopic characteristics of bulk aerosols at a coastal location of India showing signatures of continental bio-mass/biofuel burning influences during winter, whereas marine inventories (e.g., sea salt, DMS and mineral dust) appear to dominate chemical composition of summer aerosols.

Mineral dust particles in the lower atmosphere may significantly influence radiative and optical budgets, along with the net chemical balance, through their interactions with ambient chemicals. Their ability to absorb/scatter incoming radiation strongly depends on their chemical composition (i.e., distribution of major crustal elements), but as yet there is no adequate regional database with regard to this for the Indian region. To create a regional database of background mineral dust from a semi-arid zone of western India, we measured the chemical composition of ambient particles (with aerodynamic diameter ≤ 5 µm; PM_5), collected from seven locations of Jaipur city (in the vicinity of Thar Desert; Rajasthan) at varying altitudes, during late-winter of 2012. The chemical compositions of the sampled particles at both bulk and individual levels were measured using X-ray fluorescence (XRF) and Scanning Electron Microscope equipped with Energy Dispersive X-ray (SEM-EDX) techniques, respectively. Significant differences in chemical compositions were observed among the seven sites, yet the bulk chemical compositions of the particles were broadly consistent with those of individual particles. Average elemental ratios of Mg/Al, Si/Al, K/Al, Ca/Al, Mn/Al, Fe/Al were found to be 0.44 ± 0.22, 1.96 ± 0.90, 0.65 ± 0.22, 1.52 ± 0.40, 0.84 and 1.54 ± 1.67 respectively. We also estimated the complex refractive index (RIs at 550 nm wavelength) for the studied sites, yielding an average n and k (the real and imaginary parts of RI, respectively) of (1.56 ± 0.03) + (6.5 ± 4.6) × 10_(-3)i, with the aerosols collected from Kukas Hill area (27.02°N, 75.85°E) having the highest iron (Fe) mass fraction (~43%). Non-crustal elements e.g., Cu, S, C, Ag and Pb were found only in aerosols over the main city Birla Temple (Jaipur) at ground level (26.89°N, 75.81°E).

We provide the first continuous Indian Summer Monsoon (ISM) climate record for the higher Himalayas (Kedarnath, India) by analyzing a 14C-dated peat sequence covering the last ~8000 years, with ~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 ~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.

Agra is one of the largest districts of U.P. which is floristically very rich. In this region, there are many taxa which are not reported yet as in the form of floral documentations. The present study carried out on the flora of the Paliwal Park, Agra. It is spread over on area of around 70 acres (280,000 m2). In the present study a total of 76 plants species belong to 36 families have been recorded from this area. The most widely distributed plants were found in the family Moraceae (8), Caesalpiniaceae (7), Apocynaceae (5), Bignniaceae (5), Meliaceae (3) etc. There are 20 families representing only one genus and one species. The present information is important as it allows us to present or avoid the potential chance of biodiversity loss and to plan future policy for the protection of our environment.

We present here the experimental setup and standardization of a newly acquired stable isotope ratio mass- spectrometer (Isoprime 100, Isoprime UK) coupled with elemental analyzer (Pyrocube, Elementar-Germany) in a continuous flow mode, for the measurements of C, N and S isotopes in a variety of natural as well as synthetic organics and sulfur containing solid samples. We have calibrated our instrument using a suite of certified international standards supplied by International Atomic Energy Agency Vienna and cross-checked against several in-house laboratory standards used by other institutions of international repute. A synthetic organic compound Sulfanilamide was continuously used along with international standards to develop an in-house internal laboratory standard for the accurate and precise isotopic measurements. Important components contributing to the overall uncertainty of the isotopic measurements such as blank contributions, amount effect and response of mass-spectrometric current against thermal conductivity detector were per- formed using several aliquots of e-Amino-n-caproic acid and sulfanilamide (in-house) standards. Both short and long term variabilities in the measure isotopic data were assessed using our in-house laboratory standard Sulfanilamide. Overall estimated uncertainties of C, N and S isotopic measurements are better than 0.2, 0.2 and 0.3 %, respectively; which are well within the recommended limits of aforementioned isotopic data.

This article reports temporal changes in the measured oceanic geochemical properties of the Arabian Sea and the equatorial Indian Ocean by reoccupying six stations investigated during the GEOSECS expedition in 1977 and 1978. Observed differences are interpreted in terms of plausible changes in the environment and climate that have occurred in response to natural or anthropogenic processes. The depth profiles of major parameters such as dissolved oxygen, ΣCO2, major nutrients (silicates, nitrates, and phosphates), and radiocarbon in dissolved inorganic carbon were measured during the cruises between 1994 and 1998 along with temperature and salinity. Most stations in the Arabian Sea show an increase in salinity by ∼0.2 to 0.3 salinity units in the top 400 m, whereas one station in the equatorial Indian Ocean showed a decrease in salinity by ∼0.1 units, indicating a likely change in the evaporation-precipitation (E-P) balance. The ΣCO2 increased by an average of 8 μM within the top 1200 m of the Arabian Sea. The depth profiles of nitrates and dissolved oxygen for the central Arabian Sea stations show significant variations, while only marginal changes are seen for silicates and phosphates relative to the GEOSECS data. The decrease in Δ14C of surface waters is due to the steady decrease in atmospheric 14C concentration since GEOSECS, and the Δ14C increase in subsurface waters is attributed to the downward vertical diffusion of bomb 14C interpreted in terms of atmosphere to ocean transfer and lateral advection of water masses.

A 4.9-m-thick lake sequence, formed due to the landslide damming of a stream in the semiarid Garhwal Himalaya, was studied to understand past monsoonal variations in the region. The Optically Stimulated Luminescence (OSL) chronology indicates that the lake existed between ~ 12 and ~ 7 ka ago. Chronologically constrained trends of sand percent, organic phosphorus (OP), apatite inorganic phosphorus (AIP) and parameters of environmental magnetism were measured in the paleolake profile. Measured proxies indicate that the Indian summer monsoon ameliorated in the early Holocene after 12 ka cooling, and it appears that all the proxies from the lake have captured this globally recognized early Holocene warming. Four phases of wet conditions (intensified monsoon) are recognized at ~ 11.5 ka, ~ 11–10.5 ka, ~ 10–9 ka and ~ 8–7 ka with maximum uncertainties of ~ 1000 years. The wet phases are characterized by high magnetic susceptibility, increased OP and reduced AIP. In an attempt to understand the primary forcing of the sharp fluctuations in monsoonal activity in the region, we show that changes in magnetic susceptibility match variations of residual atmospheric δ14C, suggesting a role for solar variability as an explanation of climatic variability.

The Indian subcontinent with Himalayan Mountains on northern side, Bay of Bengal on eastern side, Arabian Sea on the western side and Indian Ocean on the southern side presents a unique natural setting with highly variable climatic features. The seasonal variation in North India is highly pronounced whereas in southern India it is moderate, the coastal areas are influenced by cyclones, north western India dominated by western disturbances and desert conditions. Added to these natural influences the rapid urbanization of regions resulted in changing atmospheric conditions leading to sudden occurrence of natural calamities. Prediction of these events requires very reliable climatic models which is a gigantic task. To develop climatic models suitable to our country, huge reliable data base of atmospheric parameters is required. Keeping this objective in view the Radio and Atmospheric Sciences Division of National Physical Laboratory has been engaged in monitoring the atmospheric parameters using various facilities with focus on northern plains. The present paper describes the latest research activities using the existing facilities and future activities and facilities planned in this division.

Identifying the pattern of natural climate variability is of immense importance to delineate the effects of anthropogenic climate changes. Global and regional climates are suspected to vary, in unison or with delays, with the Total Solar Irradiance (TSI) at decadal to centennial timescales. Here we show that the Indian summer monsoon rainfall correlates well with the temporal derivative of TSI on multi-decadal timescales. This linkage between the temporal derivative of TSI and the Indian summer monsoon is tested and corroborated both for the instrumental period (1871–2006) and for the last ∼300 years using a speleothem δ18O record representing rainfall in southwestern India. Our analyses indicate that anomalous dry periods of the Indian monsoon are mostly coincident with negative TSI derivative. This study thus demonstrates the potential of ‘TSI derivative’ as an important indicator of natural monsoon variability on an interdecadal timescale.