Post-monsoon Period Research Articles

Influence of climate on groundwater fluoride in different climatic domains in a hard rock terrain of Sri Lanka: implications to community health.

Health risks associated with excessive intake of fluoride through drinking water are one of the geoenvironmental health problems observed in many parts of the world, mainly in countries of the humid tropical belt, including Sri Lanka. Fluoride-related health problems are widespread in the dry climatic region compared to the wet climatic zone of Sri Lanka. The potential health risks of fluoride for communities in a river basin which drains through two climatic zones, viz. wet and dry zones, were investigated in this study. Sixty-three groundwater samples were collected from wells in the Walawe river basin during pre- and post-monsoon periods. From collected samples, ten selected samples were analyzed for their tritium (3H) levels to find out the approximate resident time of groundwater. In the river basin, the dry zone segment is characterized by elevated levels of fluoride (> 1.0mg/L) in groundwater. Groundwater fluoride in the region was primarily of geogenic origin. The tritium values showed older groundwater contained higher fluoride levels, showing a increased dissolution of fluoride-bearing minerals. The hazard quotient (HQfluoride) showed that about 45% ofpre- and 55%of post-monsoon groundwater samples in the dry zone area were unsuitable for drinking purposes for school children who are vulnerable to non-carcinogenic risks and dental fluorosis. This study emphasizes the need for continuous water quality monitoring and mitigation measures to ensure the health of residents.

Groundwater quality assessment using the weighted arithmetic index method in the selected villages of Butchayyapeta Mandal, Visakhapatnam, Andhra Pradesh, India

Groundwater quality assessment is an important measure to determine the usability of available water based on its physical, chemical, and bacteriological properties. In the present study, 10 physicochemical parameters have been considered for the groundwater quality assessment which include potential of hydrogen (pH), electrical conductivity (EC), total dissolved solids (TDS), sodium (Na+), potassium (K+), total hardness (TH), calcium (Ca2+), magnesium (Mg2+), bicarbonate (HCO3-), and chloride (Cl-). For the analysis, 21 samples for pre- and post-monsoon periods were collected from the wells/bore wells of five designated villages, Chinna Madina, Chittiyyapalem, Typuram, Rajam, and Neelakantapuram of the Butchayyapeta Mandal (sub-district) located in Visakhapatnam District, Andhra Pradesh, for the year 2017. The Bureau of Indian Standards (BIS 2012) has been used in this study to assess the suitability of the water for drinking. The water quality index (WQI) values derived by using WAI were categorized for various levels of water quality ranging from "excellent" to "unsuitable for drinking." To get the spatial distribution pattern, the WQI values of sample points were interpolated in the Arc GIS environment. The results indicated that water quality is good in the north-western parts of the current study area during pre- and post-monsoon seasons.

Japanese encephalitis in children from an endemic district of West Bengal, India: A hospital based observational study

Background: Japanese encephalitis (JE) is an important cause of viral encephalitis in children in South East Asian countries including India. Aims and Objective: We have done this study in an JE endemic district of India to know the demographic profile, clinical presentation, seasonal variation, outcome and about the vaccination status of the JE cases. Materials and Methods: This observational, cross sectional study was done for a period of one year in the Pediatric department of Burdwan Medical College, West Bengal in children up to the age of 12 year, presented with acute encephalitis syndrome (AES). Demographic data, clinical presentation and JE vaccination status were recorded and confirmed JE cases were detected by either serum or CSF JE IgM antibody. Outcome of the JE cases were noted as discharge, death or leave against medical advice (LAMA). Results: We have found confirmed JE in 18 children out of total 125 AES cases (14.4%). 61.1% of them were within 6 to 12 year age, mostly from low socioeconomic status and 100% case occurred during monsoon and post monsoon period. History, was of JE vaccination were present in only 11.1% case of JE. Most common presenting symptoms were high fever (100%), convulsion (94.4%) and altered sensorium (72.2%). 77.8% JE case were discharged and 11.1% expired. Conclusion: We must consider JE whenever a child from any endemic district comes with AES and we should try to bring every child under the JE vaccination coverage in the endemic regions globally to reduce the burden of this preventable encephalitis.

Tetracotyle wayanadensis (Trematoda: Digenea) metacercaria - A potential parasitic castrator of the freshwater fish Aplocheilus lineatus (Valenciennes, 1846): A histopathological and temporal variation study in the South Western Ghats, India.

Parasitic castration is a phenomenon where the parasite blocks or reduces the host reproductive output. This study explored the impact of Tetracotyle wayanadensis infection on the reproductive performance of the freshwater fish Aplocheilus lineatus. Heavily infected A. lineatus showed slow and sluggish movements with reduced food intake and feeding activities. Histopathological observations of the ovary revealed severe necrosis and degeneration of previtellogenic and vitellogenic oocytes and follicular atresia. The oogonial nests were absent; chromatin nucleolar oocytes irregularly shaped and vacuolated. Perinucleolar oocytes have a vacuolated appearance with the hypertrophied highly columnar follicular cells invading them. Vitellogenic oocytes had a shrunken appearance with folded zona radiata; yolk globules broken down into smaller granules together with vacuolar degeneration of the ooplasm. The hypertrophied highly columnar follicular cells invaded the early vitellogenic oocytes to phagocytize the degenerating material. Zona radiata was found broken and liquefaction of yolk globules was evident with advancement in follicular atresia. Seasonal variation of parasitic infection has also been studied. Metacercaria infecting the vital organs showed seasonal variation with the highest values for prevalence and abundance during monsoon and mean intensity during winter. The lowest values for these descriptors were documented during the post-monsoon period.

Assessment of the Receptivity of Dengue Vector Breeding through Pre- and Post-Monsoon Vector Surveillance at Some International Airports in India

As per the International Health Regulations (2005), all the International airports and seaports are to be kept free from the risk of infection through any pathogen transmitted by vectors, thereby resulting in public health hazard. Therefore, all the international airports and seaports premises are to be kept free from any vector breeding along with the 400 perimeter areas surrounding the airports and seaports. To assess the receptivity of Vector breeding i.e. Aedesaegypti (Vector for Dengue, Yellow fever, Zika and Chikunguniya), the entomological teams from the Centre for Medical Entomology and Vector Control, NCDC have been undertaking vector surveillance activities (Pre & Post Monsoon) at POE’s of some International Airports & Seaports. The vector surveillance is being done on regular basis and the findings are being shared with the respective authorities for undertaking immediate control measures. From the years 2015 to 2020, Dengue vector surveillance activities were carried out at 10 international airports including 400 meters peripheral areas during pre- and post-monsoon periods. An attempt has been made to describe the receptivity of the airports with the key findings with entomological indices with regard to the prevention and control of dengue vector and for proper planning to undertaking timely control measures to regulate the International Health Regulations in the respective international airports. Such studies on the assessment of receptivity would help the local airport health authorities in understanding the breeding potential habitats of Aedes vector and planning the appropriate vector control strategy in the respective areas.

Modified hydrologic regime of upper Ganga basin induced by natural and anthropogenic stressors

Climate change and anthropogenic activities pose serious threats to river basin hydrology worldwide. The Ganga basin is home to around half a billion people and has been significantly impacted by hydrological alterations in the last few decades. The increasing high-intensity rainfall events often create flash flooding events. Such events are frequently reported in mountainous and alluvial plains of the Ganga basin, putting the entire basin under severe flood risk. Further, increasing human interventions through hydraulic structures in the upstream reaches significantly alter the flows during the pre-and post-monsoon periods. Here, we explore the hydrological implications of increasing reservoir-induced and climate-related stressors in the Upper Ganga Basin (UGB), India. Flow/sediment duration curves and flood frequency analysis have been used to assess pre-and post-1995 hydrological behaviour. Our results indicate that low and moderate flows have been significantly altered, and the flood peaks have been attenuated by the operation of hydraulic structures in the Bhagirathi (western subbasin). The Alaknanda (eastern subbasin) has experienced an increase in extreme rainfall and flows post-1995. The downstream reaches experience reservoir-induced moderate flow alterations during pre-and post-monsoon and increasing extreme flood magnitudes during monsoon. Furthermore, substantial siltation upstream of the reservoirs has disrupted the upstream–downstream geomorphologic linkages.

English

BACKGROUND Scrub typhus is a mite borne zoonotic bacterial disease caused by Orientia tsutsugamushi. It is transmitted by bite of chiggers of trombiculid mite. Clinical features generally include fever, headache, and myalgia, with or without eschar/rash. People with severe illness may develop organ failure and bleeding which can be fatal if left untreated. This study was done to detect outbreak of cases of scrub typhus in Eastern India. These mites generally live in paddy fields of forested area and people visiting those areas are generally affected. Now a days these mites migrate to urban area resulting in increased incidence of scrub typhus infection in urban area. This study was conducted in collaboration with another institute. The purpose of this study was to find out the incidence of scrub typhus in our area and the relationship between occurrence of scrub typhus and seasonal, age and sex variation. METHODS This study was carried out in our tertiary care hospital with 441 samples for a period of one year (01.01.2019 to 31.12.19). All the blood samples collected from febrile patients were subjected to Weil Felix test. If the titre is > 1 : 160; this was further confirmed by specific IgM testing. Both Weil-Felix tests and IgM scrub typhus positive tests were noted. RESULTS Out of 441 samples, 98 (22.2 %, n = 441) samples were positive for both WeilFelix and scrub typhus IgM by enzyme linked immunosorbent assay (ELISA) testing. Most of the cases were seen in males. Seasonal distribution showed higher cases in the months of September and October. CONCLUSIONS In our study, the highest numbers of scrub typhus cases were found in rural areas, during the harvesting period of July–September specially in monsoon or post monsoon period when there is abundance of mite larva. This infection is also reported high in cases among children in the age group of 1 - 14 years. Patients who tested positive for scrub typhus improved radically with doxycycline. KEYWORDS Orientia Tsutsugamushi, Scrub Typhus, IgM ELISA

Assessment of Groundwater Quality Index, Suitability for Irrigation and Domestic Purposes in Krishna-Godavari Delta Region, Southern India

The water quality index (WQI) is a significant indicator for evaluating the quality of drinking water for end-users. The present work is aimed to assess the groundwater quality of the Krishna Godavari delta region in Andhra Pradesh State, for knowing its suitability for domestic, irrigation, and drinking purposes by calculating the WQI parameters and comparing it with WHO and Indian Standards. A total of 105 groundwater samples each for both Pre-monsoon and Post-monsoon periods have been collected during June 2017 and January 2018. The following 11 parameters were taken into account when calculating the WQI: pH, Electrical Conductivity (EC), Total Hardness (TH), Calcium (Ca2+), Magnesium (mg2+), Bicarbonate, Chloride(Cl-), Nitrate (Na+), Sulphate, Potassium (K+), and Total Dissolved Solids (TDS). Based on the WQI result, the samples were divided into five categories: Excellent, Good, Poor, Very Poor, and unfit for drinking purposes. In Pre-monsoon and Post monsoon season, the water quality index is 9%, 25%, 30%, 22%, 15% respectively 16%, 41%, 31%, 7%, and 5%. It can be concluded that during pre-monsoon and post-monsoon season 67% and 43% of water is not suitable for drinking purposes respectively and hence they require treatment before usage.

Groundwater quality assessment for irrigation by adopting new suitability plot and spatial analysis based on fuzzy logic technique

This study was focused on identifying the region suitable for agriculture-based, using new irrigation groundwater quality plot and its spatio-temporal variation with fuzzy logic technique in a geographic information system (GIS) platform. Six hundred and eighty groundwater samples were collected during pre, southwest, northeast, and post monsoon periods. A new ternary plot was also attempted to determine the irrigation suitability of water by considering four essential parameters such as sodium adsorption ratio (SAR), permeability index (PI), Sodium percentage (Na %), and electrical conductivity (EC). The derived ternary plot was the most beneficial over other available plots, as it incorporated four parameters, and it differs from the US Salinity Laboratory (USSL) plot, such that the groundwater with higher EC could also be used for irrigation purposes, depending on the Na%. The ternary plot revealed that the groundwater predominantly manifested good to moderate category during post, northeast, and southwest monsoons. The assessment with the amount of fertilizer used during the study period showed that the NPK fertilizers were effectively used for irrigation during monsoon periods. Spatial maps on EC, Kelly's ratio, Mg hazard, Na%, PI, potential salinity (PS), SAR, residual sodium carbonate (RSC), and soluble sodium percentage (SSP) were prepared for each season using fuzzy membership values, integrated for each season. A final suitability map derived by an overlay of all the seasonal outputs has identified that the groundwater in the western and the eastern part of the study area are suitable for agriculture. The study recommends cultivation of groundwater-dependent short-term crops, along the western and northern regions of the study area during the pre-monsoon season.

Recurvature and movement processes of tropical cyclones over the Bay of Bengal

AbstractActive bimodal tropical cyclones (TCs) are embedded in nonuniform flows over the Bay of Bengal (BoB). More than half of the TCs that occurred from 1990 to 2019 recurved from their original path due to the influence of 500–300 hPa steering flows. Premonsoon TCs have a tendency to turn right and make landfall on the right‐side coastal areas of the BoB. On the other hand, most of the TCs that occurred in the postmonsoon season crossed the left coast or east coast of India, despite being left or right from their path. The simulation shows that Cyclone Roanu (2016) was driven by a warm, moist, unstable southwesterly that was blocked and diverted by the hot, dry stable air masses of northerlies and northwesterlies. As a result, the TC moved along the dry–moist boundary, keeping a constant distance of ∼400 km between the eye and dryline. Conversely, the combined steering of moist southeasterly and southward‐moving upper‐level westerly jets controlled the track of postmonsoon Cyclone Madi (2013), encompassing a left turn of ∼150°. In addition to the primary steering mechanism, TC vortex propagation can be explained by the strong vertical shear (>30 m·s−1) offered by the dryline during the premonsoon period and near the monsoon trough in the postmonsoon period. This vertical shear causes the upper‐level anticyclone to tilt downshear, resulting in the forward motion of the TC vortex. The deep convection and associated mesovortices, especially those that are more prominent along the dryline, additionally influence asymmetric diabatic heating, contributing to the advection of TC potential vorticity.

Application of Cl/Br ratio to demarcate the fresh-saline water interface in coastal aquifers of northern Tamilnadu, Southern India

Geochemical parameters, chloride and bromide were used as tracers to demarcate the extent of saline water intrusion in the northern part of Tamilnadu coastal aquifer which served as a hub for major pumping well fields for supply of drinking water to Chennai city. 158 groundwater samples were collected during pre & post monsoon period to analyse the hydrochemical variations across this temporal stretch and two major water types were interpreted from the analytical data. During pre-monsoon period, Na–Cl is dominant followed by Na–HCO3 type and during post monsoon, the groundwater in the central and eastern part shift towards Na–HCO3 type from Na–Cl type. Bromide is absent in the freshwater samples, while the mixed water samples have varying bromide concentrations. In the study area, Br concentration in groundwater ranged from 0 to 22.1 mg/l while the seawater sample had Br concentration of 63 mg/l. The Cl/Br ratios of groundwater of the study area ranged from 0.01 to 188 while that of the seawater figured at 288. The groundwater of the eastern and north-eastern portion of the study area has Cl/Br ratio between 75 and 188 and this value has a similar signature to that of seawater. The continental part of the study area has Cl/Br ratio less than 50 which corresponds to that of the intermittent zone between the seawater and rainwater. Spatial distribution of Cl/Br ratio and their variation across distance from the coast indicate the remnants of seawater in the aquifer material upto 19–20 km inland and the ratio tends to decrease beyond 20 km distance. The study explores the applicability of the Cl/Br ratios for defining the extent and movement of he freshwater-saline water interface in a coastal region, which can be used by the water managers, administrators and planners for effective management and protection of available groundwater resources.

Seasonal Variability of Waterlogging in Rangpur City Corporation Using GIS and Remote Sensing Techniques

Waterlogging hazard is a significant environmental issue closely linked to land use for sustainable urbanization. NDWI is widely and effectively used in identifying and visualizing surface water distribution based on satellite imagery. Landsat 7 ETM+ and Landsat 8 OLI TIRS images of pre and post-monsoon (2002, 2019) have been used. The main objective of this study is to detect the seasonal variation of waterlogging in Rangpur City Corporation (RPCC) in 2002 and 2019. In the present study, we used an integrated procedure by using ArcGIS raster analysis. For pre and post-monsoon, almost 93% accuracy was obtained from image analysis. Results show that in 2002 during the pre and post-monsoon period, waterlogged areas were about 159.58 km2 and 32.32 km2, respectively, wherein in 2019, the changes in waterlogged areas are reversed than 2002. In 2019, during pre-monsoon, waterlogged area areas were 122.79 km2, and during post-monsoon, it increased to 127.05 km2. The research also depicts that the trend of the waterlogging situation largely depends on seasonal rainfall and a flawed drainage system.
 Keywords : Seasonal variation; Waterlogging; Remote sensing; GIS; Rangpur City Corporation
 
 Copyright (c) 2021 Geosfera Indonesia and Department of Geography Education, University of Jember
 This work is licensed under a Creative Commons Attribution-Share A like 4.0 International License

Integrated approach for the evaluation of groundwater quality through hydro geochemistry and human health risk from Shivganga river basin, Pune, Maharashtra, India.

The present study is focused on seasonal variation in groundwater quality, hydrochemistry, and associated human health risk in the Shivganga river basin, Western Maharashtra, India, to promote sustainable development of groundwater resources of this semi-arid region. The qualitative geochemical analysis, contamination levels, and human health risk assessment (HHRA) of groundwater are integral steps in groundwater management in the Deccan Plateau basalt flow region of India. Representative groundwater samples (n = 68) collected from the Shivganga River basin area of Pune district, Maharashtra, during pre-monsoon (PRM) and post-monsoon (POM) seasons in 2015 were analyzed for major cations and anions. According to the World Health Organization (WHO, 2017) drinking standards, EC, total dissolved solids, hardness, bicarbonate, calcium, and magnesium surpassed the desirable limit. Boron and fluoride content exceeded the prescribed desirable limit of the WHO. The pollution and drinking suitability were assessed by computing pollution index of groundwater (PIG), groundwater quality index (GWQI), and HHRA particularly for boron and fluoride toxicity. PIG values inferred that about 6% of groundwater samples has moderate, 24% has low, and 70% has insignificant pollution in the PRM season, while only 1 sample (3%) showed high pollution, 6% showed low, and 91% showed insignificant pollution in the POM season. GWQI classification demonstrated that 27% and 15% samples are within the poor category, and only 15% and 18% of the samples fall into excellent water category in the PRM and the POM seasons, respectively. Total hazard index (THI) revealed that 88% of children, 59% of adults, and about 38% of infants are exposed to non-carcinogenic risk, as THI values (>1) were noted for the PRM season, while 62% of children, 47% of adults, and 24% of infants are vulnerable to non-carcinogenic health hazard during the POM period.

Inter-Annual and Seasonal Variations of Water Quality and Trophic Status of a Reservoir with Fluctuating Monsoon Precipitation.

Long-term evaluation from 2000 to 2020 of a temperate reservoir indicated that water quality and trophic status were not critically controlled by the inter-annual dynamics of monsoon precipitation. The fluctuation of annual concentrations of TP, TSS, and EC did not always correlate with the variation of precipitation. BOD and COD demonstrated monotonically increasing trends with Sen’s slope of 0.02 and 0.01, respectively, while Chl-a manifested a decreasing trend (slope = −0.23). The increases of different magnitudes in the levels of TP, TSS, and Chl-a in the monsoon and the early post-monsoon periods were observed in the drought, flood, and normal years. The drought years showed distinct seasonal variations in many parameters, while those in the flood and the normal years were very similar. Pearson correlation and empirical regression analyses resulted in weaker correlation between water quality and hydrological parameters than other reservoirs, which, along with low impact of precipitation, was attributed to the low drainage ratio (28.8) of the study area. BOD/COD ratios were higher than 0.5 in the reservoir, indicating the presence of a significant fraction of biodegradable organic matter. The ratio increased in the longitudinal flow direction (>50% in the drought years), implying the possibility of autochthonous sources of organic matter. TSID evaluation resulted in variation of limiting factors not related to the fluctuation of annual precipitation. The loadings of the significant principal components were very similar among the different precipitation groups, supporting the other findings that annual precipitation governed by monsoon intensity would not solely control the water quality dynamics of the study area.

Microbial populations regulate greenhouse gas emissions in Sundarban mangrove ecosystem, India

Mangrove ecosystems are significant sources of greenhouse gases (GHG) that is attributed to microbial activity. However, it is still unknown how the sediment microbial populations affect GHG emissions in mangrove ecosystem. Since little is known about microbial populations of mangroves, the present study was aimed to understand the structure and function of microbial communities in the Indian part of the Sundarban mangrove ecosystem in relation to environmental variables and variation of GHG emissions during three seasons: pre-monsoon (March–June), monsoon (July–October) and post-monsoon (November–February).Seasonal variations of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) gas samples were taken from the mangrove bed. Culture methods were used to detect twelve different types of microbes such as heterotrophic (Htp), N2 fixing (Nfix), nitrifying (Ntfn), sulfur oxidizing (Soxd), Gram-negative (GMn), Gram-positive (GMp), spore forming (Sfor), denitrifying (DNtfn), anaerobic (Anrb), phosphate solubilizing (Psol), cellulose degrading (Cdeg) bacteria and actinomycetes (Actm). In the monsoon, populations of the Htp, Anrb, Psol, and Cdeg bacteria were more prevalent, whereas populations of the GMn, GMp, Ntfn, DNtfn bacteria, and Actm bacteria were more prevalent in the post-monsoon. Monsoonal CO2 and CH4 fluxes were larger than pre-monsoon and post-monsoon, resulting in increased microbial soil respiration and breakdown of soil organic carbon. Because of higher denitrification and soil temperature, N2O flux was higher in the pre-monsoon period, followed by monsoon and post-monsoon periods. A univariate statistical correlation was employed to assess the relationships between environmental variables and different microbial populations. An ANN (artificial neural network) model was proposed to evaluate the relevance of microbial population contribution to GHG emissions, and it indicated that the Htp, Anrb, and Dntfn microbial populations were most relevant for CO2, CH4, and N2O emissions. The suggested model would be used to assess the drivers behind GHG emission in the mangroves located at different parts of the world.

Assessment of Quality Index of Water by Using Different Physico-Chemical Parameters in Rabale Waterbody, Navi-Mumbai, Maharashtra, India

Water is a must for all living things. Reservoir and lake water is used for a variety of purposes, including drinking water, agricultural, commercial, recreational, and aquaculture. However, due to rising population pressures, which has resulted in rapid urbanization, industrialization, and modern agricultural practices, water pollution has become a major issue in recent years. The water quality index is a single number that reflects overall water quality at a specific place and time. To compute, water quality index (WQI) we used Temperature, pH, Dissolved Oxygen (DO), Biochemical Oxygen Demand (B.O.D), Chemical Oxygen Demand (C.O.D), Alkalinity, Electrical Conductivity, Turbidity, and Chemical Oxygen Demand (C.O.D), Nitrite-Nitrogen, Nitrate-Nitrogen and Hardness were the physico-chemical parameters investigated in this study. The water quality index is to transform complicated water quality data into information that the general public can use. The Water Quality Index was calculated using the Weighted Arithmetic Water Quality Index (WQI). The measured WQI was then used to assess the water quality in Rabale water body. The water quality index (WQI) of the lake was 49.813, 53.483, and 53.045 during the pre-monsoon, monsoon, and post-monsoon periods, respectively. When comparing seasonal variations, WQI values show that water status is fairly good during the pre-monsoon but is low during the monsoon and postmonsoon seasons, thus water from Rabale water body may be used for a variety of industrial purposes.

Atmospheric particle-bound mercury in the northern Indo-Gangetic Plain region: Insights into sources from mercury isotope analysis and influencing factors

Lumbini is a world heritage site located in the southern plains region of Nepal, and is regarded as a potential site for evaluating transboundary air pollution due to its proximity to the border with India. In this study, 82 aerosol samples were collected between April 2013 and July 2014 to investigate the levels of particulate-bound mercury (PBM) and the corresponding seasonality, sources, and influencing factors. The PBM concentration in total suspended particulate (TSP) matter ranged from 6.8 pg m−3 to 351.7 pg m−3 (mean of 99.7 ± 92.6 pg m−3), which exceeded the ranges reported for remote and rural sites worldwide. The Hg content (PBM/TSP) ranged from 68.2 ng g−1 to 1744.8 ng g−1 (mean of 446.9 ± 312.7 ng g−1), indicating anthropogenic enrichment. The PBM levels were higher in the dry season (i.e., winter and the pre-monsoon period) than in the wet season (i.e., the monsoon period). In addition, the δ202Hg signature indicated that waste/coal burning and traffic were the major sources of Hg in Lumbini during the pre-monsoon period. Meanwhile, precipitation occurring during photochemical processes in the atmosphere may have been responsible for the observed Δ199Hg values in the aerosol samples obtained during the monsoon period. The PBM concentration was influenced mostly by the resuspension of polluted dust during dry periods and crop residue burning during the post-monsoon period. The estimated PBM deposition flux at Lumbini was 15.7 μg m−2 yr−1. This study provides a reference dataset of atmospheric PBM over a year, which can be useful for understanding the geochemical cycling of Hg in this region of limited data.

Observations of Winter Ablation on Glaciers in the Mount Everest Region in 2020–2021

Recent observations of rising snow lines and reduced snow-covered areas on glaciers during the October 2020–January 2021 period in the Nepal–China region of Mount Everest in Landsat and Sentinel imagery highlight observations that significant ablation has occurred in recent years on many Himalayan glaciers in the post-monsoon and early winter periods. For the first time, we now have weather stations providing real-time data in the Mount Everest region that may sufficiently transect the post-monsoon snow line elevation region. These sensors have been placed by the Rolex National Geographic Perpetual Planet expedition. Combining in situ weather records and remote sensing data provides a unique opportunity to examine the impact of the warm and dry conditions during the 2020 post-monsoon period through to the 2020/2021 winter on glaciers in the Mount Everest region. The ablation season extended through January 2021. Winter (DJF) ERA5 reanalysis temperature reconstructions for Everest Base Camp (5315 m) for the 1950–February 2021 period indicate that six days in the January 10–15 period in 2021 fell in the top 1% of all winter days since 1950, with January 13, January 14, and January 12, being the first, second, and third warmest winter days in the 72-year period. This has also led to the highest freezing levels in winter for the 1950–2021 period, with the January 12–14 period being the only period in winter with a freezing level above 6000 m.

Seasonal analysis of submicron aerosol in Old Delhi using high-resolution aerosol mass spectrometry: chemical characterisation, source apportionment and new marker identification

Abstract. We present the first real-time composition of submicron particulate matter (PM1) in Old Delhi using high-resolution aerosol mass spectrometry (HR-AMS). Old Delhi is one of the most polluted locations in the world, and PM1 concentrations reached ∼ 750 µg m−3 during the most polluted period, the post-monsoon period, where PM1 increased by 188 % over the pre-monsoon period. Sulfate contributes the largest inorganic PM1 mass fraction during the pre-monsoon (24 %) and monsoon (24 %) periods, with nitrate contributing most during the post-monsoon period (8 %). The organics dominate the mass fraction (54 %–68 %) throughout the three periods, and, using positive matrix factorisation (PMF) to perform source apportionment analysis of organic mass, two burning-related factors were found to contribute the most (35 %) to the post-monsoon increase. The first PMF factor, semi-volatility biomass burning organic aerosol (SVBBOA), shows a high correlation with Earth observation fire counts in surrounding states, which links its origin to crop residue burning. The second is a solid fuel OA (SFOA) factor with links to local open burning due to its high composition of polyaromatic hydrocarbons (PAHs) and novel AMS-measured marker species for polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Two traffic factors were resolved: one hydrocarbon-like OA (HOA) factor and another nitrogen-rich HOA (NHOA) factor. The N compounds within NHOA were mainly nitrile species which have not previously been identified within AMS measurements. Their PAH composition suggests that NHOA is linked to diesel and HOA to compressed natural gas and petrol. These factors combined make the largest relative contribution to primary PM1 mass during the pre-monsoon and monsoon periods while contributing the second highest in the post-monsoon period. A cooking OA (COA) factor shows strong links to the secondary factor, semi-volatility oxygenated OA (SVOOA). Correlations with co-located volatile organic compound (VOC) measurements and AMS-measured organic nitrogen oxides (OrgNO) suggest SVOOA is formed from aged COA. It is also found that a significant increase in chloride concentrations (522 %) from pre-monsoon to post-monsoon correlates well with SVBBOA and SFOA, suggesting that crop residue burning and open waste burning are responsible. A reduction in traffic emissions would effectively reduce concentrations across most of the year. In order to reduce the post-monsoon peak, sources such as funeral pyres, solid waste burning and crop residue burning should be considered when developing new air quality policy.

Sources and health risk assessment of potentially toxic elements in groundwater in the mineral-rich tribal belt of Bastar, Central India

Concentrations of trace elements (Al, B, As, Be, Cd, Ba, Co, Cu, Fe, Cr, Sb, Ni, Li, Sn, Mn, Zn, V and Se) were determined in 160 groundwater samples, collected during pre-monsoon (PRM) and post-monsoon (POM) period (2017) in the tribal belt of Bastar, central India, using inductive coupled plasma mass spectrometry (ICP-MS). The concentrations of Al, As, Fe, Mn and Ni were found exceeding the permissible limits in 49% of samples. Cd, Sn and Se elements have shown two-fold increment in POM samples than those collected during PRM. On the contrary, Al, Ba, Co, Cr and Fe have shown a declining trend from PRM to POM period. On applying Principal component analysis (PCA) and Positive matrix factorization (PMF) approaches to the dataset, observed three primary sources (natural, geogenic and agricultural) for groundwater elemental components. Among the measured potentially toxic elements (PTEs), As has shown higher carcinogenic and non-carcinogenic risk in children as well as adults This study recommends the regular monitoring of heavy metal contamination of groundwater as various geogenic and anthropogenic activities may elevate the risk of severe health hazards.