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India has abundant water resources, including rivers and snow-covered mountains in the Himalayas, which can supply the country's water needs. In many areas, however, accessible water supplies are depleting due to fast population growth and the need to fulfill rising demands for irrigation, human and industrial consumption. Physico-chemical and microbiological characteristics were stuided of the Asan river water in Doon valley of Uttarakhand, India, that sampled were collected a fourteen water quality parameters at seven locations from October 2018 to March 2019. The water quality index and water quality maps was prepared in the Arc GIS software 10.7 using Inverse distance weighted (IDW) method. The sampled datasets were used to prepare a spatial water quality index map based on Analytical Hierarchy Process. Based on the results the weightage of the pH was found to the maximum (24%), BOD (17%), DO (13.7%), TDS (11.1%), EC (7.8%), TH (4.8%), CH (4.6%), MH (4.5%), WT (3.4%), AT (2.4%), Na (1.9%), K (1.7%), NO3(1.5%) and PO4 (1.3%). The result demonstrates that the water is heavily polluted towards station three caused due to the extensive anthropogenic activities. Thus, there is a need for combined government and non-government measures to enable the Asan rivers to slow their decline and return to their natural, pollutant-free state, which is crucial for the health of their environment. [ABSTRACT FROM AUTHOR]

The impact of long-range transported dust aerosols, originating from the Thar Desert region, to a high-altitude station in the central Himalayas was studied with the help of micro-pulse lidar (MPL) observations. A drastic change in lidar back-scatter profile was observed on a dust day as compared with that on a pre-dust day. The back-scatter coefficient on a dust day revealed that the dust layer peaked at an altitude ∼1300 m above ground level (AGL) and extended up to ∼3000 m AGL, with maximum value ∼3 × 10–5 m–1 sr–1. Aerosol Index (AI) and air mass back-trajectory analysis substantiate the transport of dust aerosols from the far-off Thar Desert region to the experimental site. A significant effect of dust aerosols was also observed over the station on the spectral aerosol optical depths (AODs), measured using a Microtops-II Sunphotometer. It showed significantly different spectral behaviour of AOD on a dust day as compared with that on a pre-dust day. The Ångström exponent (α) showed a marked decrease from 0.42 to 0.04 from the pre-dust day to the dust day. The aerosol radiative forcing estimated using the Santa Barbara DISORT (discrete ordinate radiative transfer) atmospheric radiative transfer (SBDART) model, in conjunction with the optical properties of aerosol and cloud (OPAC) model, showed values of about –30, –45 and +15 W m–2, respectively, at top-of-atmosphere (TOA), surface and in the atmosphere on the dust day. The positive atmosphere forcing caused an estimated heating of the lower atmosphere by ∼0.4 K day–1. [ABSTRACT FROM AUTHOR]

Forest fires are very common in tropical region during February–May months and are known to have significant impact on ecosystem dynamics. Moreover, aerosols emitted from these burning activities significantly modulate the Earth's radiation budget. In present study, we investigated the anomalous forest fire events and their impact on atmospheric radiation budget and glaciated snow cover over the Himalayan region. We used multiple dataset derived from satellites [Moderate Resolution Spectroradiometer (MODIS) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO)] and reanalysis models [Global Fire Assimilation System (GFAS), Second Modern-Era Retrospective analysis for Research and Application (MERRA-2) and ERA-interim] to evaluate the effect of biomass burning aerosols on radiation budget. April 2016 is associated with anomalous fire activities over lower Himalayan region in the last fourteen years (2003–2016). The model estimated organic carbon (OC) and black carbon (BC) emission reaches up to ∼3 × 10 4 and ∼2 × 10 3 μg/m 2 /day, respectively during the biomass burning period of April 2016. The meteorological data analysis accompanied with CALIOP aerosol vertical profile shows that these carbonaceous aerosols could reach up to ∼5–7 km altitude and could be transported towards glaciated region of upper Himalayas. The large amount of BC/OC from biomass burning significantly modulates the atmospheric radiation budget. The estimated columnar heating rate shows that these carbonaceous aerosols could heat up the atmosphere by ∼0.04–0.06 K/day in April-2016 with respect to non-burning period (2015). The glaciated snow cover fractions are found to be decreasing by ∼5–20% in 2016 as compared to long term mean (2003–2016). The combined analyses of various climatic factors, fires and associated BC emissions show that the observed snow cover decrease could be results of increased surface/atmospheric temperature due to combined effect of large scale climatic changes and BC absorption. Our results suggest that biomass burning can have significant effects on the Himalayan region, particularly in view of its importance in hydrological cycle and ecosystem. [ABSTRACT FROM AUTHOR]

The higher altitude regions of Himalayas and Tibetan Plateau are influenced by the dust and black carbon (BC) aerosols from the emissions and long-range transport from the adjoining areas. In this study, we present impacts of advection of polluted air masses of natural and anthropogenic emissions, on aerosol optical and radiative properties at Manora Peak (~ 2000 m amsl) in central Himalaya over a period of more than two years (February 2006–May 2008). We used the most updated and comprehensive data of chemical and optical properties available in one of the most climatically sensitive region, the Himalaya, to estimate atmospheric radiative forcing and heating rate. Aerosol optical depth (AOD) was found to vary from 0.04 to 0.45 with significantly higher values in summer mainly due to an increase in mineral dust and biomass burning aerosols due to transport. In contrast, single scattering albedo (SSA) varied from 0.74 to 0.88 with relatively lower values during summer, suggesting an increase in absorbing BC and mineral dust aerosols. As a result, a large positive atmospheric radiative forcing (about 28 ± 5 Wm − 2 ) and high values of corresponding heating rate (0.80 ± 0.14 Kday − 1 ) has been found during summer. During the entire observation period, radiative forcing at the top of the atmosphere varied from − 2 to + 14 Wm − 2 and from − 3 to − 50 Wm − 2 at the surface whereas atmospheric forcing was in the range of 3 to 65 Wm − 2 resulting in a heating rate of 0.1–1.8 Kday − 1 . [ABSTRACT FROM AUTHOR]

The impacts of an early South Asian dust storm that originated over the western part of the Middle East and engulfed northwest parts of India during the third week of March 2012 have been studied at four different stations covering India and Pakistan. The impacts of this dust storm on aerosol optical properties were studied in detail at Delhi, Jodhpur, Lahore and Karachi. The impact could also be traced up to central Himalayan foothills at Manora Peak. During dust events, the aerosol optical depth (AOD) at 500 nm reached a peak value of 0.96, 1.02, 2.17 and 0.49 with a corresponding drop in Ångström exponent (AE for 440-870 nm) to 0.01, - 0.02, 0.00 and 0.12 at Delhi, Jodhpur, Lahore and Karachi, respectively. The single scattering albedo (SSA) at 675 nm was relatively lower at Delhi (0.87) and Jodhpur (0.86), with absorption Ångström exponent (AAE) less than 1.0, but a large value of SSA was observed at Lahore (0.98) and Karachi (0.93), with AAE value greater than 1.0 during the event. The study of radiative impact of dust aerosols revealed a significant cooling at the surface and warming in the atmosphere (with corresponding large heating rate) at all the stations during dust event. The effect of this dust storm was also seen at Manora Peak in central Himalayas which showed an enhancement of ~28% in the AOD at 500 nm. The transport of dust during such events can have severe climatic implications over the affected plains and the Himalayas. [ABSTRACT FROM AUTHOR]