Browsing by Author "Ram K."
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Item Attributing Atmospheric Phosphorus in the Himalayas: Biomass Burning vs Mineral Dust(American Chemical Society, 2024) Diao X.; Widory D.; Ram K.; Du E.; Wan X.; Gao S.; Pei Q.; Wu G.; Kang S.; Wang Z.; Wang X.; Cong Z.Atmospheric phosphorus is a vital nutrient for ecosystems whose sources and fate are still debated in the fragile Himalayan region, hindering our comprehension of its local ecological impact. This study provides novel insights into atmospheric phosphorus based on the study of total suspended particulate matter at the Qomolangma station. Contrary to the prevailing assumptions, we show that biomass burning (BB), not mineral dust, dominates total dissolved phosphorus (TDP, bioavailable) deposition in this arid region, especially during spring. While total phosphorus is mainly derived from dust (77% annually), TDP is largely affected by the transport of regional biomass-burning plumes from South Asia. During BB pollution episodes, TDP causing springtime TDP fluxes alone accounts for 43% of the annual budget. This suggests that BB outweighs dust in supplying bioavailable phosphorus, a critical nutrient, required to sustain Himalayas� ecological functions. Overall, this first-hand field evidence refines the regional and global phosphorus budget by demonstrating that BB emission, while still unrecognized, is a significant source of P, even in the remote mountains of the Himalayas. It also reveals the heterogeneity of atmospheric phosphorus deposition in that region, which will help predict changes in the impacted ecosystems as the deposition patterns vary. � 2023 American Chemical Society.Item Bioaerosol emissions from wastewater treatment process at urban environment and potential health impacts(Academic Press, 2024) Vishwakarma Y.K.; Mayank; Ram K.; Gogoi M.M.; Banerjee T.; Singh R.S.The inlet of wastewater treatment plants (WWTPs) contains pathogenic microorganisms which during aeration and by mechanical mixing through wind typically aerosolized microbes into ambient air. Bioaerosol emission and its characterization (bacterial and fungal) was investigated considering low-flow and high-flow inlet of wastewater treatment plant. Generation of bioaerosols was found influenced by prevailing seasons while both during summer and winter, fungal concentration (winter: 1406 � 517; summer: 1743 � 271 CFU/m3) was higher compared to bacterial concentration (winter: 1077 � 460; summer: 1415 � 588 CFU/m3). Bioaerosols produced from WWTPs were predominately in the size range of 2.1�4.7 ?m while fraction of fungal bioaerosols were also in ultra-fine range (0.65 ?m). Bioaerosols reaching to the air from WWTPs varied seasonally and was calculated by aerosolization ratio. During summer, aerosolization of the bioaerosols was nearly 6 times higher than winter. To constitute potential health effects from the exposure to these bioaerosols, biological characterization, antibiotics resistance and the health survey of the nearby area were also performed. The biological characterization of the bioaerosols samples were done through metagenomic approach using 16s and ITS metagenomic sequencing. Presence of 167 genus of bacteria and 41 genus of fungi has been found. Out of this, bacillus (73%), curtobacterium (21%), pseudomonas, Exiguo bacterium, Acinetobacter bacillaceae, Enterobacteriaceae and Prevotella were the dominant genus (top 10) of bacteria. In case of fungi, xylariales (49%), Hypocreales (19%), Coperinopsis (9%), Alternaria (8%), Fusarium (6%), Biopolaris, Epicoccum, Pleosporaceae, Cladosporium and Nectriaceae were dominant. Antibiotics like, Azithromycin and cefixime were tested on the most dominant bacillus showed resistance on higher concentration of cefixime and lower concentration of azithromycin. Population-based health survey in WWTP nearby areas (50�150 m periphery) found several types of diseases/symptoms including respiratory problem, skin rash/irritation, change in smell and taste, eye irritation within the resident population and workers. � 2024 Elsevier LtdItem Meta-analysis of polyaromatic hydrocarbons in road dust: An emerging threat in urban environment(Elsevier B.V., 2024) Singh R.; Ram K.Road dust (RD) has emerged as a significant contributor to air pollution in urban areas. It serves as a major reservoir for various contaminants including highly toxic heavy metals and polyaromatic hydrocarbons (PAHs). Therefore, road dust poses threats not only to the environment but also human health, particularly to commuters and residents near roadsides. The abrasion of tyres and the release of carbonaceous materials from vehicle emissions further increases the toxicity of road dust. This study presents a comprehensive review of sources and fate of PAHs in road dust as well as their toxicity in the environment. We have used the Web of Science database from 1989 to 2023. Our study suggests that this research topic has seen a substantial increase in investigations with a rate of ?40 % since 2008. However, despite an increase in urbanization and industrialization and high toxicity of PAHs in RD, research in developing countries is still limited, primarily due to an inadequate funding and lack of technical advancements. Although atmospheric concentrations of PAHs have declined in developed countries, largely due to the implementation of strict emission standards and air quality regulations, adoption of advanced cleaner fuels and technologies, the demand for transport and energy is more likely to increase in developing countries in the future. Therefore, the study emphasizes the importance of promoting research on RD (size, composition and toxicity) pollution to address and mitigate the impact of PAHs on human health and the environment. Our study highlights that there is a strong need for more research on trade-off between emission and control measures to regulate RD emissions as well as toxic carcinogens including PAHs and heavy metals in urban environment. � 2024 Elsevier B.V.Item Microplastics in Different Environmental Matrices: Co-Contaminants and its Monitoring Techniques(Springer Nature, 2024) Kumar A.; Ram K.Microplastics (MPs) are tiny plastic particles ranging from 1 to 5000�?m in size and are of particular concern nowadays because of their ecological risk & health concerns. MPs are prevalent environmental contaminants and have been reported in various ecosystems such as soil, air, water, and road dust. However, a thorough understanding of their distribution across various environmental matrices remains elusive. Therefore, this review aims to fill this knowledge gap by examining the abundance of MPs and different techniques utilized for their identification and characterization including sampling, extraction, identification, characterization, and quantification methods. MPs possess a large surface area and exhibit hydrophobic properties, providing a substrate for environmental pollutants such as Polyaromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs). The primary mechanisms through which pollutants attached to MPs are hydrophobic interactions, electrostatic attraction, hydrogen bonding, halogen bonding, and ?-? interactions. Therefore, a better understanding of these interactions is crucial for determining the fate and transport of MPs and co-contaminants in the environment. Researchers commonly deploy techniques such as stereomicroscopy and spectroscopy for the characterization and quantification of MPs. However, size and chemical properties of MPs pose a challenge in their quantification, thereby necessitating the development of standardized analytical methods. Use of bio-indicators for MPs biomonitoring has gained popularity in recent years as an affordable option over conventional techniques however research in this area is limited. With this intention, the present review is designed to provide information about the status of the field and advance our knowledge of MPs in various environmental matrices. � The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.Item Nitrogen aerosols in New Delhi, India: Speciation, formation, and sources(Elsevier Ltd, 2024) Pei Q.; Wan X.; Widory D.; Ram K.; Adhikary B.; Wu G.; Diao X.; Bhattarai H.; Zhang Y.-L.; Loewen M.; Cong Z.Delhi, the capital city of India, experiences severe air pollution and suffers from its adverse effects on human health and ecosystems. This pollution is characterized by high levels of pollutants, including atmospheric nitrogen in both the gaseous and particulate phases. However, there is a lack of simultaneous measurement of chemical composition, tracers and 15N data in aerosols to understand the influence of different sources on N aerosols over Delhi. Here, we measured total nitrogen (TN), water-soluble total nitrogen (WSTN), water-soluble inorganic nitrogen (WSIN), and N stable isotope compositions (?15N) in PM2.5 samples covering the post-monsoon, winter, and summer periods of the year 2018�19. NH4+-N was the major N species, accounting for an average 58% of TN and 68% of WSIN. The temporal variations of TN, WSTN, NH4+-N, NO3?-N, and WSON showed peaks in the post-monsoon and winter seasons, exhibiting seasonality similar to PM2.5 and levoglucosan (a biomass-burning tracer) indicating their co-genetic sources. Based on the correlation analysis between ?15N and N-species, we identified two distinct secondary chemical processes: i) in an NH4+-poor atmosphere, the gas-to-particle (NH3 ? NH4+) conversion and subsequent formation of NH4HSO4 was the main process controlling the 15N and nitrogen enrichments in PM2.5; whereas ii) under NH4+-rich conditions, the formation and dissociation of NH4NO3 dominated. The coupled HYSPLIT and PSCF analyses highlighted the transport and contributions of open biomass burning emissions under a northwesterly atmospheric flow during post-monsoon as well as from local biomass combustion (from cooking and heating) during winter in the city and its vicinity. Our results suggested that i) both NH4+-N and NO3?-N were mainly impacted by biomass combustion during post-monsoon and winter seasons, and ii) NO3?-N resulted of dust transport from the Thar Desert in the summer season, but not NH4+-N. Finally, we recommend that future research focuses on the study of the seasonality of atmospheric nitrogen composition using 15N data from their different sources to design tailor-made measures and policies regarding the different potential sources, combining them within a comprehensive framework to ultimately improve air quality and the living environment in Delhi. � 2023Item Regional air quality: biomass burning impacts of SO2 emissions on air quality in the Himalayan region of Uttarakhand, India(Springer Science and Business Media B.V., 2024) Gautam A.S.; Kumar S.; Gautam S.; Singh K.; Ram K.; Siingh D.; Ambade B.; Sharma M.In the present study, continuous ground-based SO2 monitoring has been planned over the Srinagar Garhwal Valley of Uttarakhand. The monsoon (M-2018), post-monsoon (PoM-2018), winter (W-2019), pre-monsoon (PrM-2019), and M-2019 have high SO2 concentrations (3.66 � 2.05�?g/m3, 5.54 � 2.23�?g/m3, 6.42 � 1.79�?g/m3, 7.56 � 3.53�?g/m3 6.45 � 3.49�?g/m3) at 1900, 2000, 1800, 1900, and 1900 local time attributed mainly due to biomass burning and long-range transportation of pollutants. A drastic change in the SO2 concentration was observed from 4.81 to 17.39�?g/m3 in May 2019 with a strong correlation of 0.61 with fire counts during an extensive forest fire. Due to the wet scavenging process, Jul 2018 (1.07 � 0.82�?g/m3) showed the lowest SO2 concentration. Temperature, humidity, and wind speed significantly correlate with SO2 in different seasons. Overall, the air quality in the SGV region is good, but it worsens during forest fires, although it still remains within satisfactory levels. HYSPLIT model trajectories, cluster, and CWT analysis indicate the transportation of air mass from the Gulf region, Sahara Desert, Pakistan, and Afghanistan to Srinagar with a significant contribution of 40.43 to 72.29% air mass and have highest contribution more than 7�?g/m3. We have also observed weekend effects (reduction in the pollutant concentration) in Jul 2018, Sep 2018, Feb 2019, Apr 2019, and May 2019. Overall, this study highlights the seasonal variations in SO2 concentrations, the impact of forest fires on air quality, the influence of meteorological factors, the long-range transport of pollutants, and the presence of weekend effects in the SGV region of Uttarakhand. � 2023, The Author(s), under exclusive licence to Springer Nature B.V.Item Size-segregated bioaerosols concentration and characterization under diverse microenvironments(Springer Science and Business Media B.V., 2024) Vishwakarma Y.K.; Ram K.; Gogoi M.M.; Banerjee T.; Singh R.S.Scientific research on the concentration and size distribution of bioaerosols in diverse environmental conditions is recently being prioritized. Exposure to bioaerosols, especially through inhalation, is linked to many severe health complications. The inhalation of the bioaerosols is directly linked with the size as well as the nature of the bioaerosols. However, information related to the prevalence of bioaerosols is limited in India, constituting the basis for investigating variations in bacterial and fungal bioaerosol concentrations at various indoor sites. Several observational campaigns were initiated within diverse indoor sites, including cowshed, poultry, canteen, library, auditorium, laboratory, and hospital, using a six-stage viable impactor. Bacterial bioaerosols were more prevalent for size > 7.0�?m and between 1.1 and 2.1�?m. In contrast, fungal concentration peaked in the size range of 1.1 to 3.3�?m. At all the sites, the concentration of bacterial bioaerosols exceeded fungal bioaerosols (2 to 12 times), while such variation was exceptionally high in the poultry firm (70 times higher). No significant correlation was noted between bacterial and fungal bioaerosol concentration and environmental factors. The diversity of bacteria and fungi bioaerosols was found to be different as it varied from site to site. However, species like Acinetobacter and Bacillus sp. in bacteria and Penicillium, Aspergillus, and Cladosporium in fungi were most prevalent. Some of the bioaerosols found in these sites are pathogenic in nature and may cause severe health issues (if found in significant amount). The predominance of bioaerosols is mostly within the breathable range (< 3.3�?m) in diverse microenvironments. � The Author(s), under exclusive licence to Springer Nature B.V. 2024.Item Size-segregated characteristics of bioaerosols during foggy and non-foggy days of winter, meteorological implications, and health risk assessment(Royal Society of Chemistry, 2024) Vishwakarma Y.K.; Ram K.; Gogoi M.M.; Banerjee T.; Singh R.S.Fog is a common atmospheric event in northern India. Frequently, dense and prolonged fog envelops the entire Indo-Gangetic Plain (IGP), especially in the winter season. During winter, conducive atmospheric conditions also facilitate the accumulation of airborne particulates near the earth surface, significantly reducing atmospheric visibility in the presence of water vapour and gases. Besides, fog formation can also change the characteristics of the biological component of the air (bioaerosols). The Anderson six-stage bioaerosol cascade impactor was therefore used to collect bioaerosols during winter-specific foggy and non-foggy days to assess how fog formation affects the loading and characteristic of bioaerosols. It has been found that the concentration of bioaerosols increases during foggy days (2223 � 553 CFU m?3) compared to non-foggy days (days including both before and after fog; 1478 � 490 CFU m?3). Nearly, a 50% rise in the total culturable microbe concentration was noted during foggy days as compared to non-foggy days in an urban habitat over the central IGP. Approximately 46% and 55% increase in bacterial and fungal bioaerosol concentration, respectively, was found to be associated with foggy days. The size of bioaerosols also varied with the change in atmospheric conditions. During foggy days, bacterial and fungal concentration increased in the coarse size fraction (4.7-7.0 ?m) compared to fine (0.65-7.0 ?m) particles. The presence of bacteria such as Bacillus; Enterobacter; Cocci and fungi such as Aspergillus, Cladosporium and Penicillium were found during foggy days. The measured concentration of bioaerosols did not exhibit strong association with meteorological variables and other atmospheric co-pollutants. Health risk assessment of the exposure to bioaerosols revealed strong possibility to cause adverse human health effects in the exposed population. � 2024 RSC.
