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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 water quality represents the water's physical, chemical and biological properties and depends on the environment, and anthropogenic influences. Recently, river water in Dehradun has subjected to immense pressure due to contamination from indecorous land use and urbanisation. In this study area, water quality assessment is carried out with the help of in situ observations and satellite surface reflectance from October 2018 to March 2019. Physicochemical and microbial qualities, namely, ambient temperature (AT), electrical conductivity (EC), water temperature (WT), potential hydrogen (pH), free carbon di oxide (CO2), biological oxygen demand (BOD), dissolved oxygen (DO), total dissolved solids (TDS), salinity (S), total Hardness (TH), calcium hardness (CH), magnesium hardness (MgH), sodium ion (Na), Potassium ion (K), nitrate (NO2), phosphate (PO4), and coliform concentrations (CC) were evaluated in the laboratory, plotted spatially in GIS environment and validated with the Indian Standards (IS). Furthermore, the Pearson correlation matrix was an established between the mean surface reflectance band values of Landsat-8 in the Google Earth Engine (GEE) and the water quality parameters are collected at each station location. The entire river water has been found an unsuitable for drinking but suitable for irrigation purposes. In future, such studies would be supportive for more effective management strategies to overcome the problems of water pollution. [ABSTRACT FROM AUTHOR]

To monitor the spread of the novel coronavirus (COVID-19), India, during the last week of March 2020, imposed national restrictions on the movement of its citizens (lockdown). Although India's economy was shut down due to restrictions, the nation observed a sharp decline in particulate matter (PM) concentrations. In recent years, Delhi has experienced rapid economic growth, leading to pollution, especially in urban and industrial areas. In this paper, we explored the linkages between air quality and the nationwide lockdown of the city of Delhi using a geographic information system (GIS)-based approach. Data from 37 stations were monitored from 12 March, 2020 to 2 April, 2020 and it was found that the Air Quality Index for the city was almost reduced by 37% and 46% concerning PM2.5 and PM10, respectively. The study highlights that, in regular conditions, the atmosphere's natural healing rate against anthropogenic activities is lower, as indicated by a higher AQI. However, during the lockdown, this sudden cessation of anthropogenic activities leads to a period in which the natural healing rate is greater than the induced disturbances, resulting in a lower AQI, and thus proving that this pandemic has given a small window for the environment to breathe and helped the districts of Delhi to recover from serious issues related to bad air quality. If such healing windows are incorporated into policy and decision-making, these can prove to be effective measures for controlling air pollution in heavily polluted regions of the World. [ABSTRACT FROM AUTHOR]

Purpose: To determine the prevalence and risk factors for pterygium in geographically diverse regions of India. Methods: A population-based, cross-sectional multicentric study was conducted in adults aged ≥40 years in plains, hilly and coastal regions of India. All participants underwent a detailed questionnaire-based assessment for sun exposure, usage of sun protective measures, exposure to indoor smoke, and smoking. Detailed ocular and systemic examinations were performed. Pterygium was diagnosed and graded clinically by slit-lamp examination. Association of pterygium with sociodemographic, ophthalmological, and systemic parameters was assessed. Physical environmental parameters for the study period were estimated. Results: Of the 12,021 eligible subjects, 9735 (81% response rate) participated in the study. The prevalence of pterygium in any eye was 13.2% (95% CI: 12.5%-13.9%), and bilateral pterygium was 6.7% (95% CI: 6.2–7.2). The prevalence increased with age (<0.001) irrespective of sex and was highest in those aged 60–69 years (15.8%). The prevalence was highest in coastal (20.3%), followed by plains (11.2%) and hilly regions (9.1%). On multi-logistic regression, pterygium was positively associated with coastal location (P<0.001), illiteracy (P = 0.037), increasing lifetime sun exposure (P<0.001), and negatively associated with BMI ≥25 kg/m2 (P = 0.009). Conclusion: Pterygium prevalence is high in the rural Indian population. The association of pterygium with several potentially modifiable risk factors reflects its multifactorial etiology and provides targets for preventive measures. [ABSTRACT FROM AUTHOR]

Uttarakhand, an Indian Himalayan state in India, is famous for its natural environment, health rejuvenation, adventure, and a pilgrimage centre for various religions. It is categorised into two major regions, i.e., the Garhwal and the Kumaon, and geographically, the Bhabar and the Terai. Floods, cloudbursts, glacier lake outbursts, and landslides are the major natural hazards that cause the highest number of mortalities and property damage in this state. After becoming a full 27th state of India in 2000, the developmental activities have increased many folds, which has added to such calamities. This study briefly summarises the major incidents of flood damage, describes the fragile geology of this Himalayan state, and identifies the natural as well as the anthropogenic causes of the flood as a disaster. It also highlights the issue of climate change in the state and its adverse impact in the form of extreme precipitation. Besides these, it reviews the challenges involved in flood management and highlights the effective flood risk management plan that may be adopted to alleviate its adverse impacts. [ABSTRACT FROM AUTHOR]

Atmospheric new particle formation (NPF) is a crucial process driving aerosol number concentrations in the atmosphere; it can significantly impact the evolution of atmospheric aerosol and cloud processes. This study analyses at least 1 year of asynchronous particle number size distributions from six different locations in India. We also analyze the frequency of NPF and its contribution to cloud condensation nuclei (CCN) concentrations. We found that the NPF frequency has a considerable seasonal variability. At the measurement sites analyzed in this study, NPF frequently occurs in March–May (pre-monsoon, about 21 % of the days) and is the least common in October–November (post-monsoon, about 7 % of the days). Considering the NPF events in all locations, the particle formation rate (JSDS) varied by more than 2 orders of magnitude (0.001–0.6 cm -3 s -1) and the growth rate between the smallest detectable size and 25 nm (GR SDS-25 nm) by about 3 orders of magnitude (0.2–17.2 nm h -1). We found that JSDS was higher by nearly 1 order of magnitude during NPF events in urban areas than mountain sites. GR SDS did not show a systematic difference. Our results showed that NPF events could significantly modulate the shape of particle number size distributions and CCN concentrations in India. The contribution of a given NPF event to CCN concentrations was the highest in urban locations (4.3 × 10 3 cm -3 per event and 1.2 × 10 3 cm -3 per event for 50 and 100 nm, respectively) as compared to mountain background sites (2.7 × 10 3 cm -3 per event and 1.0 × 10 3 cm -3 per event, respectively). We emphasize that the physical and chemical pathways responsible for NPF and factors that control its contribution to CCN production require in situ field observations using recent advances in aerosol and its precursor gaseous measurement techniques. [ABSTRACT FROM AUTHOR]

Purpose: To determine the prevalence of cataract and its association with sun exposure and other environmental risk factors in three different geographically diverse populations of India. Design: Population based cross sectional study during 2010–2016 Participants: People aged ≥ 40 years residing in randomly sampled villages were enumerated (12021) and 9735 (81%) underwent ophthalmic evaluation from plains, hilly and coastal regions (3595, 3231, 2909 respectively) Methods: A detailed questionnaire-based interview about outdoor activity in present, past and remote past, usage of sun protective measures, exposure to smoke, and detailed ophthalmic examination including assessment of uncorrected and best corrected visual acuity, measurement of intraocular pressure, slit lamp examination, lens opacities categorization using LOCS III and posterior segment evaluation was done. Lifetime effective sun exposure was calculated using Melbourne formula and expressed as quintiles. These were supplemented with physical environmental measurements. Main outcome measures: Lifetime sun exposure hours, smoking, indoor kitchen smoke exposure and their association with cataract and subtypes. Prevalence of cataract calculated based on lens opacities or evidence of cataract surgery. Results: Cataract was identified in 3231 (33.3%) participants. Prevalence of cataract in males (32.3%) and females (34.1%) was similar. Nuclear cataract was the commonest sub-type identified in 94.7% of affected eyes. Sun exposure had a significant association with cataract with odds ratio (OR) increasing from 1.6 (95% Confidence Intervals [CI]: 1.4, 1.9) in 3rd quintile, to 2.6 (CI: 2.2, 3.1) in 4th quintile and 9.4 (CI: 7.9, 11.2) in 5th quintile (p<0.0001). Cataract also showed a significant association with smoking (OR: 1.4, CI: 1.2, 1.6) and indoor kitchen smoke exposure (OR: 1.2, CI: 1.0–1.4). Nuclear cataract showed a positive association with increasing sun exposure in 3rd (β coefficient 0.5, CI:0.2–0.7), 4th (β: 0.9, CI: 0.7–1.1) and 5th (β: 2.1, CI:1.8–2.4) quintiles of sun exposure, smoking (β: 0.4, CI: 0.2–0.6) and indoor kitchen smoke exposure (β: 0.3, CI: 01–0.5) while cortical cataract showed a positive association with sun exposure only in 5th quintile (β: 2.6, CI:1.0–4.2). Posterior subcapsular cataract was not associated with any of the risk factors. Conclusion: Cataract is associated with increasing level of sun exposure, smoking and exposure to indoor kitchen smoke. [ABSTRACT FROM AUTHOR]

Key Points: Satellite observations and Meso‐NH model simulations are used to investigate an intense dust storm over north India in June 2018Dust is mostly confined below 2 km in the monsoon flow over the Thar desert, northwest India and at ~3 km along the Ganges ValleyThe dust was accumulated in an arc‐shaped cloud in the convergence zone between the southwesterlies and the northwesterlies: the ITD A severe dust storm occurred over north India during 12–16 June 2018 is analyzed using satellite observations, reanalysis, ground‐based measurements, and model (Meso‐NH) simulations focusing on the dynamic processes that caused the dust‐storm generation, uplift, and propagation as well as its impacts on air quality. The initial dust emission was triggered by strong near‐surface southwesterlies (~15–20 m s−1) associated with the monsoon flow advancing northward, in response to the deepening of the thermal low over the Thar desert. The convergence between the northwesterlies and the monsoon flow along the Intertropical Discontinuity region caused high dust accumulation over northwest India in an area of weak winds. Convective mixing during daytime favors the vertical transport of dust to higher altitudes above the monsoon flow, but the towering Himalayas and the associated return northerly flow aloft play a blocking role leading to dust accumulation at heights between 1 and 3 km over northwest India. The prevailed northwesterlies in the middle troposphere favor the eastward transport of the dust plumes along the Ganges valley, helping to evacuate the dust toward east India. Based on Meso‐NH model simulations, the dust storm was associated with dust loads higher than 30 gm−2 and AODs higher than 3, in agreement with MODIS observations. The impact of the dust storm on the spatial‐temporal evolution of the PM10 and PM2.5 mass concentrations is studied using data from 23 air‐quality stations over northern India, indicating daily PM10 peaks reaching at ~900 μg m−3, implying a severe degradation of air quality. [ABSTRACT FROM AUTHOR]

ABSTRACT Analysis of the long-term time-series data on aerosol parameters at Delhi, an urban city in the western part of Indo-Gangetic Plain (IGP), brought out certain interesting findings. The time-series data are observed to be a complex function of different periodicities varying from intra-seasonal to inter-annual timescales. Detailed investigations of the periodicities in conjunction with the meteorological data demonstrated the prevalence of four periodicities such as intra-seasonal (periodicities of ∼2-3 months, significant at shorter wavelengths), semi-annual oscillation ( SAO, ∼6 months), annual oscillation ( AO, ∼12 months) and quasi-biennial oscillation ( QBO, ∼2 years) and quasi-triennial oscillation ( QTO, ∼3 years) at the measurement site in varying amplitudes. The AO and SAO are the dominant components in the aerosol optical depth ( AOD) as well as in the Angstrom parameters with a combined contribution of ∼40% to the climatological mean and are attributed to the changes in the prevailing meteorological conditions, which are conducive for either production, transport and/or size-transformation processes. Among the inter-annual variability in aerosol parameters, the most significant mode observed is the QTO and is found to be associated with the ENSO variability in the tropical pacific region. While the intra-seasonal fluctuations (∼2-3 months) observed in AOD (at shorter wavelengths) are associated with the eastward propagating Madden-Julian oscillations (MJO) in the lower troposphere, the biennial variability is related with variability in the meteorology of the upper and lower atmospheric regions. Periodicity analysis on aerosol parameters is useful to determine its predictability in the atmosphere. [ABSTRACT FROM AUTHOR]

The aerosols in the Indo-Gangetic Basin (IGB) are a mixture of sulfate, dust, black carbon, and other soluble and insoluble components. It is a challenge not only to identify these various aerosol types, but also to assess the optical and radiative implications of these components. In the present study, appropriate thresholds for fine-mode fraction and single-scattering albedo have been used to first identify the aerosol types over IGB. Four major aerosol types may be identified as polluted dust (PD), polluted continental (PC), black carbon-enriched (BCE), and organic carbon-enriched (OCE). Further, the implications of these different types of aerosols on optical properties and radiative forcing have been studied. The aerosol products derived from CIMEL sun/sky radiometer measurements, deployed under Aerosol Robotic Network program of NASA, USA were used from four different sites Karachi, Lahore, Jaipur, and Kanpur, spread over Pakistan and Northern India. PD is the most dominant aerosol type at Karachi and Jaipur, contributing more than 50 % of all the aerosol types. OCE, on the other hand, contributes only about 12-15 % at all the stations except at Kanpur where its contribution is ∼38 %. The spectral dependence of AOD was relatively low for PD aerosol type, with the lowest AE values (<0.5); whereas, large spectral dependence in AOD was observed for the remaining aerosol types, with the highest AE values (>1.0). SSA was found to be the highest for OCE (>0.9) and the lowest for BCE (<0.9) type aerosols, with drastically different spectral variability. The direct aerosol radiative forcing at the surface and in the atmosphere was found to be the maximum at Lahore among all the four stations in the IGB. [ABSTRACT FROM AUTHOR]

The solar global ultraviolet (GUV) and broadband global (G) radiation flux obtained on a horizontal plane in Delhi, during April 2010 to March 2011 have been used to investigate the temporal variability of these radiations and their ratio, fraction of UV (FUV). For the first time the clearness index ( KT) has been estimated over Delhi and its variability during different months of the year and season has been studied in detail. The impact of atmospheric aerosols on KT has also been studied. It has been found that for every unit increase in aerosol optical depth (AOD) at 340 nm, KT decreases by 0.06. A strong anti-correlation with correlation coefficient − 0.75 is observed between AOD and KT. On the basis of our field experience and observations at Delhi it is found that for highly cloudy and overcast conditions 0⩽ KT⩽0.15, for partial cloudy or hazy conditions 0.15⩽ KT⩽0.21 and KT > 0.21 for clear sky conditions. In addition, during foggy days in winter we have found KT values lying in the range 0.12-0.18 at Delhi. The day-time daily-averaged fluxes GUV and G varied in the range 0.15-1.23 MJ m−2 and 3.36-27.02 MJ m−2, respectively. The GUV and G showed similar pattern during the year except for the wet season when the FUV increased possibly due to an increase in water vapour concentration. Copyright © 2012 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

The characteristics of aerosol black carbon (BC) were studied at two different climatic regimes, i.e. Delhi and Manora Peak during winter and spring of 2007. Spring BC was found to be ∼59% lower at Delhi and ∼23% higher at Manora Peak than their corresponding winter BC. Diurnal BC variation showed two enhanced peaks at Delhi (morning and night) whereas a single late afternoon peak at Manora Peak. Delhi BC showed a clear correlation with prevailing winds whereas no correlation was observed at Manora Peak. The major contribution of BC at Manora Peak can be expected from biomass burning while at Delhi fossil fuel dominates. Copyright © 2012 Royal Meteorological Society [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]

Simultaneous measurements of aerosol black carbon (BC) mass concentration using an Aethalometer Model AE-42 and mixing layer height (MLH) using a monostatic sonic detection and ranging (SODAR) system were carried out from January 2006 to January 2007 at the mega-city Delhi. The BC concentration generally had a typical diurnal variation with morning and late-afternoon/night peaks. The average BC concentration during the whole period of observation was fairly high at 14.75 μg m−3. The BC concentration nearly doubled during cloudy-sky conditions compared to that during clear-sky conditions. The seasonal variation showed a maximum average concentration during the winter (25.5 μg m−3) and a minimum during the monsoon season (7.7 μg m−3), with post- and pre-monsoon values at 13.7 and 9.4 μg m−3, respectively. The average BC concentrations were strongly affected by the ventilation coefficient, a product of average wind speed (WS) and average MLH, and were found to be strongly anticorrelated. A simple model of BC concentration along with the MLH and WS was applied to estimate the average BC emission, which was found to vary in the range 11 000–17 000 kg of BC per day. The maximum emission during the day averaged every hour for different months lay in the range 1000–2100 kg h−1. The mean monthly emission varied in the range 0.35–0.52 Gg per month, giving rise to an annual estimated emission of 4.86 Gg in the year 2006 over Delhi. [ABSTRACT FROM AUTHOR]

Abstract: Simultaneous measurements of aerosol absorption and scattering coefficients for the PM2.5 aerosols particles were done at Delhi during April 2008–March 2009 to estimate the aerosol single scattering albedo (SSA) and the Angstrom absorption exponents at the surface. The annual average SSA at 0.55 μm was found to be 0.70 ± 0.07 with only slight variations during the four seasons, summer (0.63 ± 0.06), monsoon (0.69 ± 0.07), winter (0.74 ± 0.03) and spring (0.72 ± 0.04). However, large variations in average absorption and scattering coefficients were seen during these four seasons. The average absorption coefficients during summer, monsoon, winter and spring were found to be 62.47 ± 21.27, 50.95 ± 43.61, 189.65 ± 85.94 and 90.65 ± 33.06 Mm−1 respectively. The corresponding scattering coefficients were 110.46 ± 36.15, 95.34 ± 49.46, 565.59 ± 274.59 and 236.56 ± 96.25 Mm−1. The Angstrom absorption exponent (ασ(abs)) remained close to unity throughout the year averaging at 1.02 ± 0.08, 1.02 ± 0.10, 1.04 ± 0.11, and 1.03 ± 0.05 during summer, monsoon, winter and spring seasons respectively, strongly indicating that the absorption at Delhi aerosol is mainly due to the abundance of black carbon of fossil fuel origin. [ABSTRACT FROM AUTHOR]