| 1. |
- Mahanta, C., et al.
(författare)
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Preliminary assessment of arsenic distribution in brahmaputra river basin of India based on examination of 56,180 public groundwater wells
- 2015
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Ingår i: Safe and Sustainable Use of Arsenic-Contaminated Aquifers in the Gangetic Plain: A Multidisciplinary Approach. - Cham : Springer. - 9783319161242 ; , s. 57-64
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Arsenic (As) rich groundwater in alluvial aquifers is a worldwide problem (Nriagu JO, Bhattacharya P, Mukherjee AB, Bundschuh J, Zevenhoven R, Loeppert RH, Arsenic in soil and groundwater: an introduction. In: Bhattacharya P, Mukherjee AB, Bundschuh J, Zevenhoven R, Loeppert RH (eds) Arsenic in soil and groundwater environment: biogeochemical interactions, health effects and remediation. Trace metals and other contaminants in the environment, vol 9 (Ser Ed Nriagu JO). Elsevier, Amsterdam, 2007). Elevated arsenic concentrations have long been detected in Southeast Asia (e.g. Thailand, Myanmar, Vietnam, Cambodia and Lao), India, Bangladesh, China, Mongolia, Nepal and Pakistan (Smedley PL, Kinniburgh DG, Appl Geochem 17:517-568, 2002). Recent reports of discovery of arsenic (As) enrichment in groundwater of the Brahmaputra river basin (Bhattacharya P, Mukherjee A, Mukherjee AB, Arsenic contaminated groundwater of India. In: Nriagu J (ed) Encyclopedia of environmental health. Elsevier B.V, Amsterdam, 2011) has exposed a significantly large population inhabiting in the river valley to serious health threats, although the actual distribution and extent of the As affected groundwater in the aquifers are yet to be established. Because of its vicinity to the highly As rich groundwater regions of Bengal basin (Bangladesh and West Bengal state of India), the extent of the polluted areas within the Brahmaputra basin may be much wider than what is initially understood. Groundwater arsenic contamination in the Brahmaputra basin aquifers in Assam, a state in the northeastern part of India, has started gaining attention relatively recently. Singh (Arsenic contamination in groundwater of North Eastern India. In: Proceedings of 11th national symposium on hydrology with focal theme on water quality. National Institute of Hydrology, Roorkee, 2004) reported maximum groundwater arsenic concentrations in Jorhat district (Fig. 4.1), located in the southern bank of the Brahmaputra river in Assam (maximum groundwater As concentration ranges between 194 and 657 μg/L), with relatively lower concentrations in the northern bank like Lakhimpur district (50-550 μg/L). Based on studies conducted in Darrang and Bongaigaon districts located in the northern bank (Fig. 4.1) of the Brahmaputra river in Assam, Enmark and Nordborg (Arsenic in the groundwater of the Brahmaputra floodplains, Assam, India-Source, distribution and release, mechanisms. Retrieved from the url: www2.lwr.kth.se/Publikationer/PDF_Files/MFS_2007_131.pdf, 2007) reported the concentration of arsenic in the two districts between 5 and 606 μg/L. In a study conducted in 2010 (Mahanta C, Pathak N, Bhattacharya P, Enmark G, Nordborg D, Source, distribution and release mechanisms of arsenic in the groundwater of Assam floodplains of Northeast India. In: Proceedings of the World Environmental and Water Resources Congress sponsored by Environmental and Water Resources Institute (EWRI) of the American Society of Civil Engineers, 2008), concentrations beyond 50 μg/L have been confirmed in 72 blocks out of 214 blocks in 22 districts of Assam. A study by Chetia M, Chatterjee S, Banerjee S, Nath MJ, Singh D, Srivastava RB, Sarma HP (Environ Monit Assess 173:1393-1398, 2011) in the Golaghat district reported As concentration ranging between 1 and 128 μg/L in six blocks of the district. These studies so far have remained spatially limited and a comprehensive picture is yet to emerge. To comprehensively evaluate the extent of As contamination in the region, a blanket rapid assessment study was undertaken in large parts of the Brahmaputra basin in Assam. This paper reports the preliminary assessment of arsenic distribution in the Brahmaputra basin in Assam based upon results from 56,180 public groundwater wells, tested during the rapid assessment programme.
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| 2. |
- Bhattacharya, Aparajita, et al.
(författare)
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Environmental assessment of abandoned mine tailings in Adak, Vasterbotten district (northern Sweden)
- 2006
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Ingår i: Applied Geochemistry. - : Elsevier. - 0883-2927 .- 1872-9134. ; 21:10, s. 1760-1780
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Tidskriftsartikel (refereegranskat)abstract
- Sulfide-rich mine tailings in Adak that are exposed to weathering cause acid mine drainage characterized by low PH (2-4) and high SO4 (UP to 800 mg L-1). Surface water, sediment and soil samples collected in this study contain higher concentrations of As, Cu, Fe and Zn, compared to the target and/or intervention limits set by international regulatory agencies. In particular, high As concentrations in water (up to 2900 mu g L- 1) and sediment (up to 900 mg kg(-1)) are of concern. There is large variability in trace element concentrations, implying that both physical (grain size) and chemical factors (pH, secondary phases as sulfides, Al-oxides or clay minerals) play an important role in their distribution. The low PH keeps the trace elements dissolved, and they are transported farther downstream. Trace element partition coefficients are low (log K-d = 0.3-4.3), and saturation indices calculated with PHREEQC are < 0 for common oxide and sulfidic minerals. The sediment and soil samples indicate an enhanced pollution index (up to 17), and high enrichment factors for trace elements (As up to 38,300; Zn up to 800). Finally, leaves collected from different plant types indicate bioaccumulation of several elements (As, Al, Cu, Fe and Zn). However, some of the plants growing in this area (e.g., Salix, Equisetum) are generally resistant to metal toxicity, and hence, liming and phytoremediation could be considered as potential on-site remediation methods.
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| 3. |
- Bhattacharya, Manojit, et al.
(författare)
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ChatGPT's scorecard after the performance in a series of tests conducted at the multi-country level : A pattern of responses of generative artificial intelligence or large language models
- 2024
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Ingår i: Current Research in Biotechnology. - : Elsevier BV. - 2590-2628. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Recently, researchers have shown concern about the ChatGPT-derived answers. Here, we conducted a series of tests using ChatGPT by individual researcher at multi-country level to understand the pattern of its answer accuracy, reproducibility, answer length, plagiarism, and in-depth using two questionnaires (the first set with 15 MCQs and the second 15 KBQ). Among 15 MCQ-generated answers, 13 +/- 70 were correct (Median : 82.5; Coefficient variance : 4.85), 3 +/- 0.77 were incorrect (Median: 3, Coefficient variance: 25.81), and 1 to 10 were reproducible, and 11 to 15 were not. Among 15 KBQ, the length of each question (in words) is about 294.5 +/- 97.60 (mean range varies from 138.7 to 438.09), and the mean similarity index (in words) is about 29.53 +/- 11.40 (Coefficient variance: 38.62) for each question. The statistical models were also developed using analyzed parameters of answers. The study shows a pattern of ChatGPT-derive answers with correctness and incorrectness and urges for an error-free, next-generation LLM to avoid users' misguidance.
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| 4. |
- Bundschuh, J., et al.
(författare)
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Arsenic in Latin America : New findings on source, mobilization and mobility in human environments in 20 countries based on decadal research 2010-2020
- 2020
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Ingår i: Critical reviews in environmental science and technology. - : Taylor and Francis Inc.. - 1064-3389 .- 1547-6537. ; , s. 1-119
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Forskningsöversikt (refereegranskat)abstract
- Today (year 2020), the globally recognized problem of arsenic (As) contamination of water resources and other environments at toxic levels has been reported in all of the 20 Latin American countries. The present review indicates that As is prevalent in 200 areas across these countries. Arsenic is naturally released into the environment and mobilized from geogenic sources comprising: (i) volcanic rocks and emissions, the latter being transported over thousands of kilometers from the source, (ii) metallic mineral deposits, which get exposed to human beings and livestock through drinking water or food chain, and (iii) As-rich geothermal fluids ascending from deep geothermal reservoirs contaminate freshwater sources. The challenge for mitigation is increased manifold by mining and related activities, as As from mining sites is transported by rivers over long distances and even reaches and contaminates coastal environments. The recognition of the As problem by the authorities in several countries has led to various actions for remediation, but there is a lack of long-term strategies for such interventions. Often only total As concentration is reported, while data on As sources, mobilization, speciation, mobility and pathways are lacking which is imperative for assessing quality of any water source, i.e. public and private.
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| 5. |
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| 6. |
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| 7. |
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| 8. |
- Kumar, Manish, et al.
(författare)
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Lead time of early warning by wastewater surveillance for COVID-19 : Geographical variations and impacting factors
- 2022
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 441
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Forskningsöversikt (refereegranskat)abstract
- The global data on the temporal tracking of the COVID-19 through wastewater surveillance needs to be comparatively evaluated to generate a proper and precise understanding of the robustness, advantages, and sensitivity of the wastewater-based epidemiological (WBE) approach. We reviewed the current state of knowledge based on several scientific articles pertaining to temporal variations in COVID-19 cases captured via viral RNA predictions in wastewater. This paper primarily focuses on analyzing the WBE-based temporal variation reported globally to check if the reported early warning lead-time generated through environmental surveillance is pragmatic or latent. We have compiled the geographical variations reported as lead time in various WBE reports to strike a precise correlation between COVID-19 cases and genome copies detected through wastewater surveillance, with respect to the sampling dates, separately for WASH and non-WASH countries. We highlighted sampling methods, climatic and weather conditions that significantly affected the concentration of viral SARS-CoV-2 RNA detected in wastewater, and thus the lead time reported from the various climatic zones with diverse WASH situations were different. Our major findings are: i) WBE reports around the world are not comparable, especially in terms of gene copies detected, lag-time gained between monitored RNA peak and outbreak/peak of reported case, as well as per capita RNA concentrations; ii) Varying sanitation facility and climatic conditions that impact virus degradation rate are two major interfering features limiting the comparability of WBE results, and iii) WBE is better applicable to WASH countries having well-connected sewerage system.
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| 9. |
- Mukherjee, Abhijit, et al.
(författare)
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Elevated arsenic in deeper groundwater of the western Bengal basin, India : Extent and controls from regional to local scale
- 2011
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Ingår i: Applied Geochemistry. - : Elsevier. - 0883-2927 .- 1872-9134. ; 26:4, s. 600-613
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Tidskriftsartikel (refereegranskat)abstract
- The deeper groundwater (depending on definition) of the Bengal basin (Ganges-Brahmaputra delta) has long been considered as an alternate, safe drinking-water source in areas with As-enrichment in near-surface groundwater. The present study provides the first collective discussion on extent and controls of elevated As in deeper groundwater of a regional study area in the western part of the Bengal basin. Deeper groundwater is defined here as non-brackish, potable (Cl- <= 250 mg/L) groundwater available at the maximum accessed depth (similar to 80-300 m). The extent of elevated As in deeper groundwater in the study area seems to be largely controlled by the aquifer-aquitard framework. Arsenic-enriched deeper groundwater is mostly encountered north of 22.75 degrees N latitude, where an unconfined to semi-confined aquifer consisting of Holocene- to early Neogene-age gray sand dominates the hydrostratigraphy to 300 m depth below land surface. Aquifer sediments are not abnormally enriched in As at any depth, but sediment and water chemistry are conducive to As mobilization in both shallow and deeper parts of the aquifer(s). The biogeochemical triggers are influenced by complex redox disequilibria. Results of numerical modeling and profiles of environmental tracers at a local-scale study site suggest that deeper groundwater abstraction can draw As-enriched water to 150 m depth within a few decades, synchronous with the advent of wide-scale irrigational pumping in West Bengal (India).
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| 10. |
- Mukherjee, Abhijit, et al.
(författare)
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Occurrence, predictors and hazards of elevated groundwater arsenic across India through field observations and regional-scale AI-based modeling
- 2021
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 759
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Tidskriftsartikel (refereegranskat)abstract
- Existence of wide spread elevated concentrations of groundwater arsenic (As) across South Asia, including India, has endangered a huge groundwater-based drinking water dependent population. Here, using high-spatial resolution As field-observations (similar to 3 million groundwater sources) across India, we have delineated the regional-scale occurrence of elevated groundwater As (>= 10 mu g/L), along with the possible geologic-geomorphologic-hydrologic and human-sourced predictors that influence the spatial distribution of the contaminant. Using statistical and machine learning method, we also modeled the groundwater As concentrations probability at 1 Km resolution, along with probabilistic delineation of high As-hazard zones across India. The observed occurrence of groundwater As was found to be most strongly influenced by geology-tectonics, groundwater-fed irrigated area (%) and elevation. Pervasive As contamination is observed in major parts of the Himalayan mega-river Indus-Ganges-Brahmaputra basins, however it also occurs in several more-localized pockets, mostly related to ancient tectonic zones, igneous provinces, aquifers in modern delta and chalcophile mineralized regions. The model results suggest As-hazard potential in yet-undetected areas. Our model performed well in predicting groundwater arsenic, with accuracy: 82% and 84%; area under the curve (AUC): 0.89 and 0.88 for test data and validation datasets. An estimated similar to 90 million people across India are found to be exposed to high groundwater As from field-observed data, with the five states with highest hazard are West Bengal (28 million), Bihar (21 million), Uttar Pradesh (15 million), Assam(8.6 million) and Punjab (6 million). However it can be much more if the modeled hazard is considered (>250 million). Thus, our study provides a detailed, quantitative assessment of high groundwater As across India, with delineation of possible intrinsic influences and exogenous forcings. The predictive model is helpful in predicting As-hazard zones in the areas with limited measurements.
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| 11. |
- Mukherjee, A., et al.
(författare)
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Wide spread arsenic in deeper groundwater of western Bengal basin, West Bengal, India : Implications for sustainable alternate drinking water sources
- 2012
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Ingår i: Understanding the Geological and Medical Interface of Arsenic, As 2012. - : Taylor & Francis Group. ; , s. 522-525
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Konferensbidrag (refereegranskat)abstract
- Availability of safe drinking water is a major concern in the delta plains of the major Himalayan-Tibetan rivers in southern and southeastern Asia. While indiscriminate use of rivers and other surface water bodies for disposal of sewage and industrial waste has rendered them non-potable, natural, non-point source, elevated Arsenic (As) concentrations in groundwater exceeding the World Health Organization's (WHO) guideline value for drinking water of 0.01 mg/L have put millions of people at risk. Hence, finding an alternate, suitable and sustainable drinking-water source has been a priority in these areas. Generally, higher concentrations of dissolved As are found in groundwater of shallower aquifers and several studies have advocated deeper aquifers as a possible safe substitute. Using a composite hydrogeological approach, we demonstrate that regional-scale deeper groundwater As contamination in the western Bengal basin is dependent on the aquifer-aquitard framework and complex redox processes with partial equilibrium under natural flow conditions. Widespread deep irrigation pumping may be drawing shallower, contaminated groundwater down to greater depths. These findings have severe implications on finding alternate drinking water sources, in West Bengal, and adjoining areas of Bangladesh, with plausible similar geological and hydrogeological framework.
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| 12. |
- Routh, Joyanto, 1968-, et al.
(författare)
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Arsenic remobilization from sediments contaminated with mine tailings near the Adak mine in Vasterbotten district (northern Sweden)
- 2007
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Ingår i: Journal of Geochemical Exploration. - : Elsevier BV. - 0375-6742 .- 1879-1689. ; 92:1, s. 43-54
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Tidskriftsartikel (refereegranskat)abstract
- Weathering of mine tailings have resulted in high As concentrations in water (up to 2900 mu g 1(-1)) and sediment (up to 900 mg kg(-1)) samples around the Adak mine. Notably, As occurs as As(III) species (15-85%) in the oxic surface and ground water samples, which is not common. Time-series based sediment incubations were set up in the laboratory with contaminated sediments to study the microbial processes involved in transformation and remobilization of As across the sediment-water interface. The microcosm experiments indicate that microorganisms are capable of surviving in As-rich sediments and reduce As(V) to As(III). A decrease in total As concentration in sediments is coupled to an increase in As(Ill) concentration in the aqueous media. In contrast, the controls (treated with HgCl, and formaldehyde) did not show growth, and As(V) concentrations increased steadily in the sediments and aqueous medium. The results imply that active metabolism is necessary for As(V) reduction. These microorganisms possess reduction mechanisms that are not necessarily coupled to respiration, but most likely impart resistance to As toxicity.
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| 13. |
- Abarca, R. R. M., et al.
(författare)
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Metals toxic pollutants in the environment : Anthropogenic and geological causes and remediation
- 2019
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Ingår i: Current Trends and Future Developments on (Bio-) Membranes: Membranes in Environmental Applications. - : Elsevier Inc.. ; , s. 109-124
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Heavy metals are naturally present in nature, but if their concentration is higher than the normal accepted threshold levels, they constitute one of the pollutants that is more difficult to remove and also to rehabilitate the contaminated site by them. There are many heavy-metal pollutants-the most common among them are arsenic (As), chromium (Cr), lead (Pb), mercury (Hg), cadmium (Cd), cobalt (Co), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se), and zinc (Zn), along with the less common ones, which produced, for example, by the nuclear process, such as uranium (U)-in different configuration; hence, many possibilities of contamination in the world exist, and they are more difficult to remove.Thus heavy-metal pollution is more and more becoming one of the principal issues of the global interest, because it is common to both industrialized countries and developing countries. These issues are getting hard to be recognized and cannot be followed the simple rules concerning safety and environmental protection, thus fall into the same errors of the already industrialized countries. At the same time, new environment-remediation techniques are developed in the last decade, especially, in these last years. Some of these technologies concern physical or chemical process or effects, such as ion exchanges, flotations, and photocatalysis, while other technologies concern the use of membrane process, especially ultrafiltration or membrane integrated process or hybrid systems, where membranes are generally submerged and used together with another process.In this chapter a review of this problem and some example of technologies for removing and remediation of the environment are reported.
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| 14. |
- Abiye, T. A., et al.
(författare)
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Arsenic concentration in groundwater : Archetypal study from South Africa
- 2019
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Ingår i: Groundwater for Sustainable Development. - : Elsevier. - 2352-801X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- South Africa does not have significant surface water resources, which is often easily affected by unpredictable and rapidly changing climatic variables, due to its location in the arid and semi-arid climatic setting. In large part of the country, groundwater from weathered and fractured crystalline rocks plays pivotal role in sustaining the livelihood, often it contains toxic metals released from the host rocks. The host rocks that are responsible for arsenic release in groundwater are primarily enriched due to metamorphism and igneous processes that resulted in the enrichment of economic minerals. Preliminary assessment indicates that the main arsenic containing minerals are arsenopyrite (FeAsS), arsenical oxide, sulpharsenide, arsenopyritical reefs, leucopyrite, löllingite (FeAs2) and scorodite (FeAsO4·2H2O). Owing to the release of arsenic from highly mineralized rocks that constitute the aquifers, arsenic concentration in the groundwater reaches up to 253 μg/L (Namaqualand), 6150 μg/L (west of Johannesburg), about 500 μg/L in the Karoo aquifers, considerably higher than the WHO guideline value of 10 μg/L. Acid mine drainage from coal and gold mining is also found to be an important source of arsenic and other toxic metals in groundwater.
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| 15. |
- Abu-Khader, M. M., et al.
(författare)
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Radon in the groundwater in the Amman-Zarqa Basin and related environments in Jordan
- 2018
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Ingår i: Groundwater for Sustainable Development. - : Elsevier. - 2352-801X. ; 7, s. 73-81
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Tidskriftsartikel (refereegranskat)abstract
- The occurrence of radon (222Rn) in environment (groundwater and indoor air) from geogenic sources is receiving an growing attention due to its adverse impact on human health worldwide including Jordan. Highlighting the current status of radon in Jordan, the present study of radon concentrations in ground waters in the Amman-Zarqa basin (AZB) was investigated. Groundwater samples were collected from fifteen wells located in three main areas of Ras Al-Ain, Al-Rsaifeh and Al-Hashemite. Radon concentration was measure using Liquid scintillation counting (LSC) Tri- Carb 3110 with discriminator and the highest values for radon concentration in water were observed in Al-Rsaifeh area and ranged from 4.52 up to 30.70 Bq/l with an average of 11.22 Bq/l, which were attributed to the decay of naturally distributed uranium in phosphate rock from Al-Rsaifeh mines. In Ras Al-Ain area, the radon concentration were noted ranged from 0.6 to 5.55 Bq/l with an average of 2.82 Bq/l, and also in Al-Hashemite area were ranged from 0.77 to 5.37 Bq/l with an average of 4.04 Bq/l. The overall average concentration of tested samples was 5.77 Bq/l and found within the acceptable international levels. Ground water samples of Ras Al-Ain area showed good quality as was tested of low salinity. It recorded the lowest average radon concentration of 2.82 Bq/l. Also, Radon indoor and building materials was reviewed. In conclusion, this study presented an urged need for developing national regulations and standards as well as awareness program concerning the radon status in Jordan.Elsevier B.V.
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| 16. |
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| 17. |
- Ahmad, Arslan, et al.
(författare)
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Advanced Oxidation-Coagulation-Filtration (AOCF) - An innovative treatment technology for targeting drinking water with <1 μg/L of arsenic
- 2014
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Ingår i: One Century of the Discovery of Arsenicosis in Latin America (1914-2014). - : CRC Press. - 9781138001411 ; , s. 817-819
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Konferensbidrag (refereegranskat)abstract
- Advanced Oxidation-Coagulation-Filtration (AOCF) has been investigated for producing drinking water with less than 1 μg L-1 of As through a series of bench scale and pilot scale experiments. At bench scale, the suitable coagulant, its combination dose with KMnO4 oxidant, the optimum process pH and kinetics of As removal were determined. The optimized AOCF technique was capable of consistently reducing the As concentration to below 1 μg L-1 when implemented at pilot scale and did not adversely affect the already existing removal processes of Fe, Mn and NH4 +. Dual media filter solved the filter run time reduction issue.
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| 18. |
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| 19. |
- Ahmad, Arslan, et al.
(författare)
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Arsenic reduction to < 1 mu g/L in Dutch drinking water
- 2020
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Ingår i: Environment International. - : Elsevier. - 0160-4120 .- 1873-6750. ; 134
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Forskningsöversikt (refereegranskat)abstract
- Arsenic (As) is a highly toxic element which naturally occurs in drinking water. In spite of substantial evidence on the association between many illnesses and chronic consumption of As, there is still a considerable uncertainty about the health risks due to low As concentrations in drinking water. In the Netherlands, drinking water companies aim to supply water with As concentration of < 1 mu g/L - a water quality goal which is tenfold more stringent than the current WHO guideline. This paper provides (i) an account on the assessed lung cancer risk for the Dutch population due to pertinent low-level As in drinking water and cost-comparison between health care provision and As removal from water, (ii) an overview of As occurrence and mobility in drinking water sources and water treatment systems in the Netherlands and (iii) insights into As removal methods that have been employed or under investigation to achieve As reduction to < 1 mu g/L at Dutch water treatment plants. Lowering of the average As concentration to < 1 mu g/L in the Netherlands is shown to result in an annual benefit of 7.2-14 M(sic). This study has a global significance for setting drinking water As limits and provision of safe drinking water.
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| 20. |
- Ahmad, Arslan, et al.
(författare)
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Arsenite removal in groundwater treatment plants by sequential Permanganate-Ferric treatment
- 2018
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Ingår i: Journal of Water Process Engineering. - : ELSEVIER SCIENCE BV. - 2214-7144. ; 26, s. 221-229
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Tidskriftsartikel (refereegranskat)abstract
- The Dutch drinking water sector is actively investigating methods to reduce arsenic (As) to < 1 mu g/L in drinking water supply. We investigated (1) the effectiveness of sequential permanganate (MnO4-)-ferric (Fe(III)) dosing during aeration-rapid sand filtration to achieve < 1 mu g/L As (2) the influence of MnO4--Fe(III) dosing on preestablished removal patterns of As(III), Fe(II), Mn(II) and NH4+ in rapid sand filters and (3) the influence of MnO4--Fe(III) dosing on the settling and molecular-scale structural properties of the filter backwash solids. We report that MnO4--Fe(III) dosing is an effective technique to improve arsenite [As(III)] removal at groundwater treatment plants. At a typical aeration-rapid sand filtration facility in the Netherlands effluent As concentrations of < 1 mu g/L were achieved with 1.2 mg/L MnO4--and 1.8 mg/L Fe(III). The optimized combination of MnO4-and Fe(III) doses did not affect the removal efficiency of Fe(II), Mn(II) and NH4+ in rapid sand filters, however, the removal patterns of Fe(II) and Mn(II) in rapid sand filter were altered, as well as the settling behaviour of backwash solids. The characterization of backwash solids by Fe K-edge X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) showed that the changed settling velocity of backwash solids with MnO4-Fe(III) in place was not due to changes in the molecular-scale structure of Fe-precipitates that constitute the major portion of the backwash solids.
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| 21. |
- Ahmad, Arslan, et al.
(författare)
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Characteristics of Fe and Mn bearing precipitates generated by Fe(II) and Mn(II) co-oxidation with O-2, MnO4 and HOCl in the presence of groundwater ions
- 2019
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Ingår i: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 161, s. 505-516
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we combined macroscopic measurements of precipitate aggregation and chemical composition (Mn/Fe solids ratio) with Fe and Mn K-edge X-ray absorption spectroscopy to investigate the solids formed by co-oxidation of Fe(II) and Mn(II) with O-2, MnO4, and HOCl in the presence of groundwater ions. In the absence of the strongly sorbing oxyanions, phosphate (P) and silicate (Si), and calcium (Ca), O-2 and HOCl produced suspensions that aggregated rapidly, whereas co-oxidation of Fe(II) and Mn(II) by MnO4 generated colloidally stable suspensions. The aggregation of all suspensions decreased in P and Si solutions, but Ca counteracted these oxyanion effects. The speciation of oxidized Fe and Mn in the absence of P and Si also depended on the oxidant, with O-2 producing Mn(III)-incorporated lepidocrocite (Mn/Fe = 0.01-0.02 mol/mol), HOCl producing Mn(III)-incorporated hydrous ferric oxide (HFO) (Mn/Fe = 0.08 mol/mol), and MnO4 producing poorly-ordered MnO2 and HFO (Mn/Fe > 0.5 mol/mol). In general, the presence of P and Si decreased the crystallinity of the Fe(III) phase and increased the Mn/Fe solids ratio, which was found by Mn K-edge XAS analysis to be due to an increase in surface-bound Mn(II). By contrast, Ca decreased the Mn/Fe solids ratio and decreased the fraction of Mn(II) associated with the solids, suggesting that Ca and Mn(II) compete for sorption sites. Based on these results, we discuss strategies to optimize the design (i.e. filter bed operation and chemical dosing) of water treatment plants that aim to remove Fe(II) and Mn(II) by co-oxidation.
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| 22. |
- Ahmad, Arslan, et al.
(författare)
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Environmental arsenic in a changing world
- 2019
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Ingår i: Groundwater for Sustainable Development. - : Elsevier. - 2352-801X. ; 8, s. 169-171
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Tidskriftsartikel (refereegranskat)
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| 23. |
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| 24. |
- Ahmad, Arslan, et al.
(författare)
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Impact of phosphate, silicate and natural organic matter on the size of Fe(III) precipitates and arsenate co-precipitation efficiency in calcium containing water
- 2020
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Ingår i: Separation and Purification Technology. - : ELSEVIER. - 1383-5866 .- 1873-3794. ; 235
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Tidskriftsartikel (refereegranskat)abstract
- Removal of arsenic (As) from water by co-precipitation with Fe(III) (oxyhydr)oxides is a widely used technique in water treatment. Nevertheless, As removal efficiency appears to be sensitive to the composition of the water matrix. The aim of this study was to gain a deeper understanding of the independent and combined effects of silicate (Si), phosphate (P), natural organic matter (NOM) and calcium (Ca) on arsenate [As(V)] co-precipitation efficiency and the size of Fe(III) precipitates. We found that, in complex solutions, containing multiple solutes and high levels of Ca, (variations in) Si and P concentrations reduce As(V) removal to some extent, mainly due to a decreased adsorption of As(V) onto Fe(III) precipitates. On the other hand, NOM concentrations reduced As(V) removal to a much greater extent, due to possible formation of mobile Fe(III)-NOM complexes that were difficult to remove by filtration. These findings have a great significance for predicting As(V) removal as a function of seasonal and process-related water quality changes at water treatment plants.
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| 25. |
- Ahmad, Arslan, et al.
(författare)
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Mobility and redox transformation of arsenic during treatment of artificially recharged groundwater for drinking water production
- 2020
-
Ingår i: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 178
-
Tidskriftsartikel (refereegranskat)abstract
- In this study we investigate opportunities for reducing arsenic (As) to low levels, below 1 mu g/L in produced drinking water from artificially infiltrated groundwater. We observe that rapid sand filtration is the most important treatment step for the oxidation and removal of As at water treatment plants which use artificially recharged groundwater as source. Removal of As is mainly due to As co-precipitation with Fe(III)(oxyhydr)oxides, which shows higher efficiency in rapid sand filter beds compared to aeration and supernatant storage. This is due to an accelerated oxidation of As(III) to As(V) in the filter bed which may be caused by the manganese oxides and/or As(III) oxidizing bacteria, as both are found in the coating of rapid sand filter media grains by chemical analysis and taxonomic profiling of the bacterial communities. Arsenic removal does not take place in treatment steps such as granular activated carbon filtration, ultrafiltration or slow sand filtration, due to a lack of hydrolyzing iron in their influent and a lack of adsorption affinity between As and the filtration surfaces. Further, we found that As reduction to below 1 mu g/L can be effectively achieved at water treatment plants either by treating the influent of rapid sand filters by dosing potassium permanganate in combination with ferric chloride or by treating the effluent of rapid sand filters with ferric chloride dosing only. Finally, we observe that reducing the pH is an effective measure for increasing As co-precipitation with Fe(III)(oxyhydr)oxides, but only when the oxidized arsenic, As(V), is the predominant species in water.
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| 26. |
- Ahmed, Firoz, et al.
(författare)
-
First detection of SARS-CoV-2 genetic material in the vicinity of COVID-19 isolation Centre in Bangladesh : Variation along the sewer network
- 2021
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 776
-
Tidskriftsartikel (refereegranskat)abstract
- We made the first and successful attempt to detect SARS-CoV-2 genetic material in the vicinity wastewaters of an isolation centre i.e. Shaheed Bhulu Stadium, situated at Noakhali, Southeastern Bangladesh. Owing to the fact that isolation centre, in general, always contained a constant number of 200 COVID-19 patients, the prime objective of the study was to check if several drains carrying RNA of coronavirus are actually getting diluted or accumulated along with the sewage network. Our finding suggested that while the temporal variation of the genetic load decreased in small drains over the span of 50 days, the main sewer exhibited accumulation of SARS-CoV-2 RNA. Other interesting finding displays that probably distance of sampling location in meters is not likely to have a significant impact on the detected gene concentration, although the quantity of the RNA extracted in the downstream of the drain was higher. These findings are of immense value from the perspective of wastewater surveillance of COVID-19, as they largely imply that we do not need to monitor every wastewater system, and probably major drains monitoring may illustrate the city health. Perhaps, we are reporting the accumulation of SARS-CoV-2 genetic material along with the sewer network i.e. from primary to tertiary drains. The study sought further data collection in this line to simulate conditions prevailed in most of the developing countries and to shed further light on decay/accumulation processes of the genetic load of the SARS-COV-2.
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| 27. |
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| 28. |
- Ahmed, K. Matin, et al.
(författare)
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Arsenic enrichment in groundwater of the alluvial aquifers in Bangladesh : an overview
- 2004
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Ingår i: Applied Geochemistry. - : Elsevier BV. - 0883-2927 .- 1872-9134. ; 19:2, s. 181-200
-
Tidskriftsartikel (refereegranskat)abstract
- Arsenic in the groundwater of Bangladesh is a serious natural calamity and a public health hazard. Most groundwater from the shallow alluvial aquifers (<150 m), particularly in the Holocene plain lands, are vulnerable to As-enrichment. Delta plains and flood plains of the Ganges-Brahmaputra river system are moderately to severely enriched and more than 60% of the tube wells are affected. Shallow aquifers in the Meghna river basin and coastal plains are extremely enriched with more than 80% of the tube wells affected. Aquifers in the Pleistocene uplands and Tertiary hills are low in As. The vertical lithofacies sequence of the sediments from highly enriched areas of the country show two distinct lithofacies associations-a dominantly sandy channel-fill association and a fine-grained over bank association. The sediments can be grouped into 4 distinct lithofacies, viz. clay, silty clay, silty sand and sand. Thin section petrography of the As-enriched aquifer sands shows that the sands are of quartzolithic type and derived from the collision suture and fold thrust belt of the recycled orogen provenance. Groundwater is characterized by circum-neutral pH with a moderate to strong reducing nature. The waters are generally of Ca-Mg-HCO3 or Ca-Na-HCO3 type, with HCO3- as the principal anion. Low SO42- and NO3-, and high dissolved organic C (DOC) and NH4+ concentrations are typical chemical characteristics of groundwater. The presence of dissolved sulfides in these groundwaters indicates reduction Of SO4. Total As concentration in the analyzed wells vary between 2.5 and 846 mug l(-1) with a dominance of As(III) species (67-99%). Arsenic(III) concentrations were fairly consistent with the DOC and NH4+ contents. The HNO3 extractable concentrations of As (As-NO3) in the sediments (0.5-17.7 mg kg(-1)), indicate a significant positive correlation with Fe-NO3, Mn-NO3, Al-NO3 and P-NO3. The concentrations Of S-NO3 (816-1306 mg kg(-1)) peaked in the clay sediments with high organic matter (up to 4.5 wt.%). Amounts of oxalate extractable As (As..) and Fe (Fe x) ranged between 0.1-8.6 mg kg(-1) and 0.4-5.9 g kg(-1), respectively. Arsenic(ox) was positively correlated with Fe-ox, Mn-ox, and Al-ox in these sediments. Insignificant amounts of opaque minerals (including pyrite/arsenopyrite) and the presence of high As contents in finer sediments suggests that some As is incorporated in the authigenically precipitated sulfides in the reducing sediments. Moreover, the chemical extractions suggest the presence of siderite and vivianite as solid phases, which may control the aqueous chemistry of Fe and PO43-. Reductive dissolution of Fe oxyhydroxide present as coatings on sand grains as well as altered mica (biotite) is envisaged as the main mechanism for the release of As into groundwater in the sandy aquifer sediments.
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| 29. |
- Ahmed, K. M., et al.
(författare)
-
Groundwater arsenic mitigation in Bangladesh : Two decades of advancements in scientific research and policy instruments
- 2014
-
Ingår i: One Century of the Discovery of Arsenicosis in Latin America (1914-2014). - 9781138001411 ; , s. 886-888
-
Konferensbidrag (refereegranskat)abstract
- Two decades have passed since the first detection of arsenic above allowable limits in groundwater of Bangladesh. A good number of scientific research and mitigation projects have so far been completed but still today more than 22 million people are exposed to arsenic leaves of 50 μg L-1 or more. As there are many untested new wells, it is not precisely known how many people are exposed to what level. Scientific knowledge about occurrences, distribution and release mechanisms have enhanced significantly. Although deep tube wells have emerged as the most effective mitigation measure over most of the country, still there are areas where this does not work. Recent studies reported effectiveness of alternative options like intermediate deep wells and subsurface arsenic removal. There has been a major paradigm shift in the policy arena regarding arsenic mitigation.
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| 30. |
- Ahmed, K. M., et al.
(författare)
-
Groundwater quality contrasts between Upper and Lower Dupi Tila Aquifers in Megacity Dhaka, Bangladesh
- 2011
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Ingår i: Groundwater quality contrasts between Upper and Lower Dupi Tila Aquifers in Megacity Dhaka, Bangladesh. - 9781907161162 ; , s. 71-74
-
Konferensbidrag (refereegranskat)abstract
- Dhaka is one of the fastest growing megacities of the world and is set to become the third largest by 2025. Currently about 86% of the municipal water supply comes from over 500 wells drilled in the Dupi Tila aquifers underlying the city. The Upper Dupi Tila aquifer (UDTA) is overexploited and a large part has been dewatered; abstractions from the lower Dupi Tila started only recently. Results of water analysis and EC surveys have been used to decipher the variations in groundwater quality in the UDTA and LDTA. EC surveys reveal a systematic deterioration of water quality in the vicinity of the Buriganga River in southeast Dhaka. The UDTA is more widely affected by anthropogenic processes than the LDTA, which still largely exhibits its intrinsic water quality characteristics. Regular monitoring and proper management practices are essential to protect the quality of this precarious resource.
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| 31. |
- Ahmed, K. M., et al.
(författare)
-
Implementation of arsenic mitigation : Insights from Araihazar and Matlab – two extensively studied areas in Bangladesh
- 2018
-
Ingår i: Environmental Arsenic in a ChangingWorld - 7th International Congress and Exhibition Arsenic in the Environment, 2018. - London : CRC Press/Balkema. - 9781138486096 ; , s. 565-566
-
Konferensbidrag (refereegranskat)abstract
- Despite many efforts over the last 25 years, millions of people are still drinking groundwater having arsenic above Bangladesh and World Health Organization limits. This can be linked, to some extent, to a lack of pragmatic policies and implementation strategies. Important lessons have been learned from extensive studies in Araihazar and Matlab in Bangladesh. Also better mitigation strategies for reducing arsenic exposure have been demonstrated at both locations. New policy and mitigation strategies should focus on mapping using mobile technology for village scale mapping. Dissemination of test result is extremely important in increasing awareness of the users and a new three-color scheme (Blue, Green, Red corresponding to <10, 10–50, and >50 µg L−1) instead of existing Red-Green color scheme should be adopted to lower arsenic intake. Safe wells can be installed at appropriate locations and depth by combining hydrogeological and social criteria aided by applications-based score ranking.
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| 32. |
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| 33. |
- Alam, Mohammad Ayaz, et al.
(författare)
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An appraisal of the principal concerns and controlling factors for Arsenic contamination in Chile
- 2023
-
Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- Although geogenic Arsenic (As) contamination is well-recognized in northern Chile, it is not restricted to this part of the country, as the geological conditions favoring As release to the human environment exist across the country as well, although not at the same level, based on comparatively fewer studies in central and southern Chile. The present work provides a critical evaluation of As sources, pathways, and controls with reports and case studies from across the country based on an exhaustive bibliographic review of its reported geogenic sources and processes that affect its occurrence, systematization, and critical revision of this information. Arc magmatism and associated geothermal activities, identified as the primary As sources, are present across the Chilean Andes, except for the Pampean Flat Slab and Patagonian Volcanic Gap. Metal sulfide ore zones, extending from the country's far north to the south-central part, are the second most important geogenic As source. While natural leaching of As-rich mineral deposits contaminates the water in contact, associated mining, and metallurgical activities result in additional As release into the human environment through mining waste and tailings. Moreover, crustal thickness has been suggested as a principal controlling factor for As release, whose southward decrease has been correlated with lower As values.
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| 34. |
- Alam, M.S., et al.
(författare)
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Controls of sedimentary facies on arsenic mobilization in shallow aquifers of the Matlab North Upazila, southeastern Bangladesh
- 2013
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Groundwater extracted from shallow (<100 m bgl) Holocene alluvial aquifers, is the primary source of drinking water in Matlab North Upazila, Southeast Bangladesh. The distribution of lithofacies and its relation to hydrochemistry in such heterogeneous deposits are of fundamental importance for the analysis of groundwater quality. Aquifer sediment samples were collected from 48 locations throughout the study area. Lithofacies distribution was characterized using grain size and sediment colors. Channel fills (sandy) and over bank (silt-clay) deposits the two main lithofacies groups, were identified. These sandy deposits represent an active meandering river or channel fills sediment sequence, which are usually capped by silts and clays of an over bank sediment sequence. All the collected sediments samples were generalized and subdivided based on four distinct color variations, such as Black, White, Off-white, and Red according to Munsell color chart and water-well drillers’ perception.Mineral compositions showed variability with the sediment color and grain size. Red and off-white sediments contain fewer amounts of metastable minerals (hornblende, actinolite, kyanite and pyroxenes etc.) than that of black sediments, whereas black sediments contain higher amount of biotite. The relatively high content of biotite and other dark colored ferromagnesian minerals are responsible for the black and grayish color of these sediments. Ferruginous coating on silicates, particularly on quartz grains, gives the red and off-white coloration. Based on the available information regarding sediment colors of aquifers in which tubewell screens were placed, 44 domestic hand pumped tubewells (HTWs) were selected for water sampling. The groundwater abstracted from black sediments of shallow aquifer showed higher concentrations in DOC (median: 5.81 mg/L), dissolved NH4+ (median: 3.47 mg/L), PO43- (median: 1.36 mg/L), Fe (median: 4.87 mg/L), As (median: 252.53 μg/L) and relatively low Mn (median: 0.54 mg/L) and SO42-(median: 0.59 mg/L) concentrations, whereas groundwater abstracted from off-white and red sediments of shallow aquifer showed lower concentrations in DOC (median: 1.95 and 1.71 mg/L, respectively), dissolved NH4+ (median: 0), PO43- (median: 0.14 and 0.04 mg/L, respectively), Fe (median: 2.25 and 0.63 mg/L, respectively), As (median: 17.36 and 15.05 μg/L, respectively) and relatively high Mn+2 (median: 1.12 and 1.15 mg/L, respectively) and SO42- (median: 0.79 and 0.78 mg/L, respectively) concentrations. The water samples collected from black sediments (median Eh: 211 mV) indicated most reducing environment, followed by white (median Eh: 227 mV), whereas off-white and red sediments (median Eh: 268 and 274 mV) signified less reducing environment. The study supports that the sediment colors in shallow aquifer can be a reliable indicator of high and low-As concentrations and can be a useful tool for local drillers to target arsenic safe aquifers.
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| 35. |
- Ali, S., et al.
(författare)
-
Concentration of fluoride in groundwater of India : A systematic review, meta-analysis and risk assessment
- 2019
-
Ingår i: Groundwater for Sustainable Development. - : Elsevier. - 2352-801X. ; 9
-
Forskningsöversikt (refereegranskat)abstract
- It is a well-known fact that the Indian groundwater is polluted by fluoride. However, for the first time in India, non-carcinogenic risk assessments and meta-analysis of fluoride exposure to humans were carried out due to consumption of groundwater. In this context, we collected fluoride concentration data in groundwater across India by systematic searches conducted in various international search engines databases. Here, we demonstrated a detailed meta-analysis and meta-regression of fluoride and evaluated health risk assessment. For this purpose, meta-analysis of 63 studies on fluoride in groundwater in India, comprising 57381 samples are included. We found that 1.) The pooled concentration of fluoride in India is around 2.37 mg/L with 95% confident interval (1.46–3.28 mg/L) which is higher than WHO and national standards limit of 1.5 mg/L. 2) The meta-analysis of data suggests that in rural parts of the country, fluoride concentration is 1.85 times higher than urban areas. 3) The concentration of fluoride in groundwater decreased significantly (p < 0.05) with increase in rainfall and longitude. The risk assessment via oral and dermal route exposure reveals that the consumers in majority of the regions are at considerable non-carcinogenic risk and children are at higher risk than adults (Total hazard quotient > 1). The findings are helpful in identifying the affected areas of India and we recommend that the safer options of drinking water should be adopted.
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| 36. |
- Ali, S., et al.
(författare)
-
Elevated fluoride in groundwater of Siwani Block, Western Haryana, India : A potential concern for sustainable water supplies for drinking and irrigation
- 2018
-
Ingår i: Groundwater for Sustainable Development. - : Elsevier BV. - 2352-801X. ; 7, s. 410-420
-
Tidskriftsartikel (refereegranskat)abstract
- Groundwater pollution is a serious health concern in north-western India. In this study, we have reported very high concentration of fluoride i.e. 18.5 and 16.6 mg/l from Sainiwas locality in Siwani block of Bhiwani district, Haryana, India. The values are much higher than the permissible limit set by WHO and BIS. The evapotranspiration in the area leads to Ca2+ precipitation, which allows an increase in F- content in the groundwater. In addition, the replacement of hydroxyl of secondary clay mineral under alkaline condition is responsible for release of F-. In absence of alternative source, the fluoride polluted groundwater in some of these localities is also used for drinking. Further, the suitability of groundwater for irrigation is also evaluated by various parameters such as Sodium Adsorption Ratio (SAR), Sodium Percentage (Na%), Kelly's Ratio (KR), Magnesium Hazard (MH) and Residual Sodium Carbonate (RSC). It emerges out that in a few localities, groundwater is not suitable for irrigation and with respect to Magnesium Hazard (MH) almost all samples are unsuitable for irrigation. This article highlights groundwater quality of Siwani block in Haryana and proposes for immediate remedial measures.
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| 37. |
- Ali, S., et al.
(författare)
-
Influence of the water–sediment interaction on the major ions chemistry and fluoride pollution in groundwater of the Older Alluvial Plains of Delhi, India
- 2021
-
Ingår i: Journal of Earth System Science. - : Springer Nature. - 2347-4327 .- 0973-774X. ; 130:2
-
Tidskriftsartikel (refereegranskat)abstract
- Fluoride (F–) pollution in groundwater of the Older Alluvial Plain (OAP) of Delhi has been reported as a major problem. About 34% of the groundwater samples collected for this study had F– level beyond the permissible limit; with F– concentration in the range of 0.14–3.15 mg/L (average 1.20 mg/L). In this context, this article for the first time attempts on the genesis of major ions chemistry and F– pollution in groundwater of OAP Delhi by going beyond the statistical analysis to sediment geochemistry, chemical weathering processes and understanding of the processes using stable environmental isotopes (2H and 18O). The XRD of the OAP sediments revealed the dominance of fluor-biotite, albite, calcite, quartz, and chlorite. Whereas, the separated clay revealed the dominance of chlorite, kaolinite, and illite minerals. The saturation index (SI) values indicated that the groundwater chemistry is in the process of further F– enrichment by way of sediment groundwater interaction. With the given mineralogy of the sediments, the dominance of major ions like Na+, K+, Mg2+, Ca2+, Cl– and F– has been attributed to chemical weathering of biotites, phlogopites, albite, and calcite during sediment–water interaction. While the dominance of SO42– has been attributed to anthropogenic sources and confirmed by its association with heavier stable isotopes of hydrogen (δ2H: −50.44 to −40.02‰) and oxygen (δ18O: −7.19 to −5.62‰) indicating evaporative enrichment during isotopic fractionation.
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| 38. |
- Amin, Nuhu, et al.
(författare)
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Dependency of sanitation infrastructure on the discharge of faecal coliform and SARS-CoV-2 viral RNA in wastewater from COVID and non-COVID hospitals in Dhaka, Bangladesh
- 2023
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 867
-
Tidskriftsartikel (refereegranskat)abstract
- The detection of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) RNA in wastewater can be used as an indicator of the presence of SARS-CoV-2 infection in specific catchment areas. We conducted a hospital-based study to explore wastewater management in healthcare facilities and analyzed SARS-CoV-2 RNA in the hospital wastewater in Dhaka city during the Coronavirus disease (COVID-19) outbreak between September 2020-January 2021. We selected three COVID-hospitals, two non-COVID-hospitals, and one non-COVID-hospital with COVID wards, conducted spot-checks of the sanitation systems (i.e., toilets, drainage, and septic-tank), and collected 90 untreated wastewater effluent samples (68 from COVID and 22 from non-COVID hospitals). E. coli was detected using a membrane filtration technique and reported as colony forming unit (CFU). SARS-CoV-2 RNA was detected using the iTaq Universal Probes One-Step kit for RT-qPCR amplification of the SARS-CoV-2 ORF1ab and N gene targets and quantified for SARS-CoV-2 genome equivalent copies (GEC) per mL of sample. None of the six hospitals had a primary wastewater treatment facility; two COVID hospitals had functional septic tanks, and the rest of the hospitals had either broken onsite systems or no containment of wastewater. Overall, 100 % of wastewater samples were positive with a high concentration of E.coli (mean = 7.0 log10 CFU/100 mL). Overall, 67 % (60/90) samples were positive for SARS-CoV-2. The highest SARS-CoV-2 concentrations (median: 141 GEC/mL; range: 13-18,214) were detected in wastewater from COVID-hospitals, and in non-COVID-hospitals, the median SARS-CoV-2 concentration was 108 GEC/mL (range: 30-1829). Our results indicate that high concentrations of E. coli and SARS-CoV-2 were discharged through the hospital wastewa-ter (both COVID and non-COVID) without treatment into the ambient water bodies. Although there is no evidence for transmission of SARS-CoV-2 via wastewater, this study highlights the significant risk posed by wastewater from health care facilities in Dhaka for the many other diseases that are spread via faecal oral route. Hospitals in low-income settings could function as sentinel sites to monitor outbreaks through wastewater-based epidemiological surveillance systems. Hospitals should aim to adopt the appropriate wastewater treatment technologies to reduce the discharge of pathogens into the environment and mitigate environmental exposures.
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| 39. |
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| 40. |
- Amiri, V., et al.
(författare)
-
Groundwater quality evaluation using Shannon information theory and human health risk assessment in Yazd province, central plateau of Iran
- 2020
-
Ingår i: Environmental Science and Pollution Research. - : Springer. - 0944-1344 .- 1614-7499.
-
Tidskriftsartikel (refereegranskat)abstract
- This study aims to evaluate the quality of groundwater in the most arid province of Iran, Yazd. It is highly dependent on groundwater resources to meet the domestic, industrial, and agricultural water demand. Position of water samples on the modified Gibbs diagram demonstrates that the interaction with silicates and the increase in direct cation exchange are responsible for the increased salinity of groundwater. Based on entropy theory, the decreasing order of importance of variables in controlling groundwater chemistry is Fe > As > Ba > Hg > NO2 > Pb > K > Cl > Na > Mg > SO4 > NO3 > HCO3 > Ca. The results of entropy weighted water quality index (EWWQI) calculation show that about 34 and 32% of 206 samples in the wet and dry seasons, respectively, are classified as extremely poor quality (ranks 4 and 5). Approximately 60 and 55% of 206 samples in wet and dry seasons, respectively, have excellent, good, and medium quality (ranks 1, 2, and 3). The non-carcinogenic human health risk (NHHR) from intake and dermal contact pathways using deterministic approach show that 36 and 17 samples in both seasons are not suitable for drinking by children. Furthermore, 9 and 2 samples are not suitable for drinking by adults. The results show that children are more vulnerable than adults to these health risks. The non-carcinogenic risks through dermal contact were negligible.
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| 41. |
- Amiri, Vahab, et al.
(författare)
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Mercury pollution in the coastal Urmia aquifer in northwestern Iran : potential sources, mobility, and toxicity
- 2021
-
Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media Deutschland GmbH. - 0944-1344 .- 1614-7499. ; 28:14, s. 17546-17562
-
Tidskriftsartikel (refereegranskat)abstract
- The concentration of total dissolved mercury (HgT) in surface and groundwater resources in the coastal parts of Urmia aquifer (NW of Iran) was investigated to identify the possible sources and sinks of mercury and the geochemical mechanisms controlling its mobilization. The distribution of water samples on the Piper diagram demonstrates that most samples have the Ca-Mg-HCO3 facies. From 62 water samples collected in this area, one sample contained HgT concentrations exceeding the maximum contaminant level recommended by the WHO (6 μg/L). The principal component analysis (PCA) produced five principal components. The positive moderate correlation of HgT with EC, Cl, K, Mg, and Na indicated that the weathering of geological formations was one of the main sources of mercury in groundwater samples. Position of water samples in Eh-pH regions where microorganisms involved in mercury methylation and mineralization were potentially active demonstrated that the aquifer had undergone sulfate reduction and had reached the final stage of the terminal electron accepting process (TEAP) sequence in the methane production processes which are limited to only 37% of the water samples that have anaerobic conditions. Some Hg-bearing species are in nonequilibrium geochemical conditions. The supersaturation of water samples with magnetite and goethite indicated that these Fe-bearing minerals could act as the strong reducing agents for the reduction of Hg(II) to Hg(0).
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| 42. |
- Amiri, V., et al.
(författare)
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The hydrogeochemical evaluation of groundwater resources and their suitability for agricultural and industrial uses in an arid area of Iran
- 2021
-
Ingår i: Groundwater for Sustainable Development. - : Elsevier BV. - 2352-801X. ; 12
-
Tidskriftsartikel (refereegranskat)abstract
- The hydrogeochemical and quality status of groundwater resources in Yazd province, the central plateau of Iran, has been investigated. The most common water type, followed by chemical facies in this study area, is Cl type (with 50.46%) and Na–Cl facies (47.71%), respectively. Besides, the most samples with industrial and agricultural uses show the Cl type and Na–Cl hydrochemical facies. The position of samples on the Gibbs and van Wirdum diagrams indicate that the water-rock interaction and dissolution of evaporites are the main controlling process of water chemistry. Distribution of samples based on Na/Cl vs. EC, Ca + Mg vs. SO4 + HCO3, and Na–Cl vs. Ca + Mg–SO4–HCO3 highlight the significant role of direct ion exchange in water chemistry change. The water quality for agricultural use is assessed based on some indices including EC, Na%, sodium absorption ratio (SAR), residual sodium carbonate (RSC), magnesium absorption ratio (MAR), permeability index (PI), Kelly's ratio (KR), and Wilcox diagram. In general, the water quality for irrigation purposes is mainly excellent to permissible. The water quality assessment for industrial purposes is performed using some indices including Langelier Saturation Index (LSI), Ryznar Stability Index (RSI), Larson-Skold Index (L-SI), Puckorious scaling index (PSI), and total hardness (TH). Based on these indices, most groundwater samples have mild to high potential to corrode the equipment and pipelines.
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| 43. |
- Amofah, Lea Rastas, et al.
(författare)
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Extraction of arsenic from soils contaminated with wood preservation chemicals
- 2010
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Ingår i: Soil & sediment contamination. - : Informa UK Limited. - 1532-0383 .- 1549-7887. ; 19:2, s. 142-159
-
Tidskriftsartikel (refereegranskat)abstract
- Three soil samples contaminated by chromated zinc arsenate (CZA) or chromated copper arsenate (CCA) were investigated in a laboratory scale to study As mobilization and to identify a chemical agent that could be used in soil washing to extract arsenic. Besides high As extraction, the cost, occupational health issues and technical aspects were considered when selecting the chemical. Arsenic is strongly bound to CZA/CCA soils; only ∼50% of the tot-As was removed from water-washed soils. High Fe or Al mobilization is not necessarily indicative of high As removal from CZA/CCA soils. A high Cu/As-ratio and a large amount of soluble Ca in the soil hampered As extraction. The high ratio can be an indication of stable Cu-arsenates in soil. Calcium can react with the extraction agent or with As during extraction. Sodium hydroxide, dithionite with citrate (and oxalate) (dithionite solutions), and oxalate with citrate were the most efficient chemicals for removing As from the soils. The disadvantages of using these strong chemicals are: a high cost (oxalate with citrate); damage to equipment (dithionite solutions); an adverse impact on occupational health (dithionite solutions); or a deterioration in soil quality after extraction (NaOH and dithionite solutons). Phosphate, solutions based on NH2OH·HCl, or citrate were not efficient in mobilizing As from the soils.
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| 44. |
- Amofah, Lea Rastas, et al.
(författare)
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The influence of temperature, pH/molarity and extractant on the removal of arsenic, chromium and zinc from contaminated soil
- 2011
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Ingår i: Journal of Soils and Sediments. - : Springer Science and Business Media LLC. - 1439-0108 .- 1614-7480. ; 11:8, s. 1334-1344
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Normal soil washing leave high residual pollutant content in soil. The remediation could be improved by targeting the extraction to coarser fractions. Further, a low/high extraction pH and higher temperature enhance the pollutant removal, but these measures are costly. In this study, the utility of NaOH, oxalate-citrate (OC) and dithionite-citrate-oxalate (DCO) solutions for extracting of arsenic, chromium and zinc from contaminated soil were assessed and compared. In addition the effects of NaOH concentration and temperature on NaOH extractions, and those of temperature and pH on OC and DCO extractions, were evaluated. Materials and methods: A two-level, full-factorial design with a centre point was implemented. Two factors, concentration and temperature,were evaluated in NaOH extractions, and pH and temperature for OC and DCO solutions. In all cases, the extraction temperature was 20°C, 30°C and 40°C. The studied NaOH concentrations were 0.05, 0.075 and 0.1 M. The pH in OC solutions was 3, 5 and 7, and in DCO solutions, 4.7, 6.3 and 6.7. Water-washed and medium coarse soil fraction of arsenic, chromium and zinc contaminated soil was agitated for 15 min with the extraction solution. Results and discussion: In NaOH extractions, the temperature and (less strongly) NaOH concentration significantly affected As and Cr mobilisation, but only the latter affected Zn mobilisation. Both pH and temperature significantly (and similarly) influenced As and Cr mobilisation in OC extractions, while only the pH influenced Zn mobilisation. In contrast, the extraction temperature (but not pH) influenced As, Cr and Zn mobilisation in DCO extractions. Conclusions: For all extractants, mobilisation was most efficient at elevated temperature (40°C). None of the extractants reduced the soil's As content to below the Swedish EPA's guideline value. Use of DCO is not recommended because dithionite has a short lifetime and residual arsenic contents in DCO-extracted soil are relatively high. Instead, sequential extraction with NaOH followed by OC solutions (affording significant reductions in As, Cr and Zn levels in the soil with short extraction times) at 40°C is recommended.
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| 45. |
- Annaduzzaman, Md, et al.
(författare)
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Arsenic and manganese in shallow tubewells : validation of platform color as a screening tool in Bangladesh
- 2018
-
Ingår i: Groundwater for Sustainable Development. - : Elsevier B.V.. - 2352-801X. ; 6, s. 181-188
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to evaluate the potential of handpump tubewell platform color as a low-cost, quick and convenient screening tool for As and Mn in drinking water tubewells. For this study, groundwater samples and corresponding tubewell platform pictures were collected from 272 shallow tubewells in Matlab Upazila of South-Eastern Bangladesh. The result shows that arsenic concentration within the surveyed (n = 272) tubewells, 99% (n = 269) exceeded the World Health Organization (WHO) guideline value of 10 µg/L, and 98% (n = 267) exceeded the Bangladesh drinking water standards (BDWS) of 50 µg/L. In relation to the platform color concept, within 233 (total 272) red colored platform tubewells, 230 (99%) exceeded the WHO guideline value of 10 µg/L, and 229 (98%) tubewells exceeded BDWS of 50 µg/L. This result shows a strong correlation between the development of red color stain on tubewell platform and As concentrations in the corresponding tubewell water. This study suggests that red-colored platform can be used for primary identification of tubewells with an elevated level of As and thus could prioritize sustainable As mitigation management in developing countries where water comes from reductive shallow aquifers. This study did not confirm the potential for Mn screening, as red discoloration by Fe oxides was found to mask the black discoloration of Mn oxides. It is recommended to further investigate this screening tool in regions with a higher well-to-well variability of As contaminations, as in the presented study As was found >10ug/L in 99% of the tubewells.
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| 46. |
- Annaduzzaman, Md., et al.
(författare)
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Characterization of a chitosan biopolymer and arsenate removal for drinking water treatment
- 2014
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Ingår i: One Century of the Discovery of Arsenicosis in Latin America (1914-2014). - : CRC Press. - 9781138001411 ; , s. 745-747
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Konferensbidrag (refereegranskat)abstract
- Chitosan biopolymer with a deacetylation degree of 85%, was assessed for its capability to adsorb As(V) from drinking water by batch experiments. To characterize the chitosan biopolymer, chitosan was analyzed by FTIR and SEM. The results showed that chitosan is an effective and promising sorbent for As(V) from drinking water. From the batch tests, results showed a maximum adsorption of 355 μg/L of As(V) with 1.18 μg g-1 adsorption capacity at pH 6. The kinetic data, obtained at pH 6 could be fitted with pseudo-second order equation (adsorption capacity: 0.923 μg g-1) and the process was suitably described by a Freundlich (R2 = 0.9933) model than by a Langmuir model (R2 = 0.9741). The results above indicated that chitosan is a very favorable sorbent for As(V) removal from aqueous solution.
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| 47. |
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| 48. |
- Annaduzzaman, Md, 1986-
(författare)
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Chitosan biopolymer as an adsorbent for drinking water treatment : Investigation on Arsenic and Uranium
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In many countries over the world (including Sweden), metal toxicity in freshwater resources causes a severe drinking water quality problem and poses a threat to the environment and human health. Among the different toxic metals in the water resources of Sweden, arsenic and uranium are the biggest threats to health. These elements, over long time consumption, may even lead to cancer and/or neurological disorder. Most of the wells are installed in crystalline and sedimentary bedrock and the received water comes from water bearing fractures in the bedrock. The handling of such water is an issue and there is a need to reduce the arsenic and uranium exposure by improving processes and technologies. It is a very serious problem demanding a safe, sustainable and eco-friendly arsenic and uranium removal technology prior to drinking water supply. Different treatment systems are available, but many of them are not suitable due to their high cost, operation complexity and waste management issues. Through this study, chitosan biopolymer the second largest abundant polysaccharide on earth after cellulose, was verified as a potential adsorbent for arsenic(V) and uranium(VI) removal from water solution. Adsorbent characterizations were also conducted by XRD, FTIR, SEM, UV-visible spectrum and TGA/DTA investigations. Bench-scale batch experiments were conducted using chitosan biopolymer (DDA-85%) as an adsorbent to determine the arsenic(V) and uranium(VI) removal efficiency, by allowing four important effective parameters e.g. chitosan dosages, pH, contact time and contaminant concentration. The adsorption data at optimum conditions were fitted with Langmuir, Freundlich and Dubinin-Radushkhevic (D-R) isotherm and Lagergren pseudo-first-order and pseudo-second-order kinetic model to investigate the adsorption process. The characterization of materials assured the presence of effective amino, hydroxyl, and carboxyl groups of chitosan. Another advanntage is that the materials are bio-degradable. The results show that the arsenic(V) and uranium(VI) removal efficiency was 100% and 97.45% after 300 minutes with optimum pH of 6.0 and 7.0 respectively. The optimum adsorbent dosages and initial concentration were 60 and 80g/L and 100 and 250 µg/L respectively. The adsorption process was suitably described by Freundlich isotherm (R2 = 0.9933) and Langmuir isotherm (R2 = 0.9858) correspondingly for arsenic(V) uranium(VI) compared to other isotherms. This is an important indicator of homogeneous monolayer adsorption of metals. For both of arsenic(V) and uranium(VI), pseudo-second-order explained the adsorption kinetics better than pseudo-first-order and the second-order kinetic regression coefficient (R2) were 0.9959 and 0.9672 correspondingly. Connecting to the above mentioned results, it can be summed up that the chitosan biopolymer (DDA 85%) can be used as an inexpensive, sustainable and environment-friendly treatment option for arsenic(V) and uranium(VI) contaminated drinking water.
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| 49. |
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| 50. |
- Annaduzzaman, Md., et al.
(författare)
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Tubewell platform color : A low-cost and rapid screening tool for arsenic and manganese in drinking water
- 2013
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Presence of high level of geogenic arsenic (As) in groundwater is one of the major and adverse drinking water quality problem all over the world, especially in Southeast Asia, where groundwater is the prominent drinking water source. Bangladesh is already considered as one of the most As affected territories, where As contamination in the groundwater is key environmental disasters. Recently besides As, presence of high level of manganese (Mn) in drinking water has also got attention due to its neurological effect on children. It becomes very essential to formulate a reliable safe drinking water management policy to reduce the health threat caused by drinking As and Mn contained groundwater. The development of a simple low cost technique for the determination of As and Mn in drinking water wells is an important step to formulate this policy. The aim of this study was to evaluate the potentiality of tubewell platform color as low-cost, quick and convenient screening tool for As and Mn in drinking water wells (n=272) in a highly arsenic affected area on Matlab, Southeastern Bangladesh.The result shows strong correlation between the development of red color stain on tubewell platform and As enrichment in the corresponding tubewell water compared to WHO drinking water guideline (10 μg/L) as well as Bangladesh drinking water standard (BDWS) (50 μg/L), with certainty values of 98.7% and 98.3% respectively. The sensitivity and efficiency of red colored platforms to screen high As water in tubewells are 98% and 97% respectively at 10 μg/L, whereas at cut-off level of 50μg/L both sensitivity and efficiency values are 98%. This study suggests that red colored platform could be potentially used for primary identification of tubewells with elevated level of As and thus could prioritise sustainable As mitigation management in developing countries. Due to lack of tubewells with black colored platform in the study area, the use of platform color concept for screening of Mn enriched water in the wells have not been tested significantly, which requires further study.Acknowledgements: This study was carried out with support from the Liuuaeus-Palme Academic Exchange Programme supported by International Programs Office (IPK) and the KTH led joint collaborative action research project on Sustainable Arsenic Mitigation- SASMIT (Sid Contribution 750000854).
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