Дисертації з теми "Groundwater – Arsenic content – Vermont"
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Uddin, G. M. Saleh. "Groundwater contamination by arsenic in Bangladesh : causes, consequences and solutions." Title page, table of contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09ENV/09envu18.pdf.
Повний текст джерелаChoudhury, Zubaida Akhtar. "Groundwater arsenic pollution in Bangladesh : a study of water consumption behaviour and decision-making processes within rural communities." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610220.
Повний текст джерелаFerreira, Gabriela Ribeiro de Sena. "Arsenic Mobilization from Silicic Volcanic Rocks in the Southern Willamette Valley." PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/2752.
Повний текст джерелаCHENG, PEI-CHENG, and 程培正. "Arsenic Content in Arsenic-enriched Soil Crops and Methods for Reducing Arsenic in Groundwater." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/a526vx.
Повний текст джерела朝陽科技大學
環境工程與管理系
106
According to the EPA survey, most of the main causes of arsenic pollution in agricultural land in China are caused by long-term arsenic-based groundwater irrigation. The pollution range is mainly distributed in the Lanyang Plain, the Zhuoshuixi Alluvial Fan, the Jianan Plain and the Pingtung Plain, covering a wide area. In the face of so many arsenic-rich agricultural land caused by geological factors, the cost of rectification is quite large. If the geological factors are not improved, the safety of planting edible vegetables in arsenic-rich soils needs to be evaluated. Biochar has the function of changing soil properties and carbon sequestration, and is agronomic material that is currently actively promoted in agriculture and environmental protection. In this study, biochar was prepared from agricultural waste rice husks, and biochar was applied at a weight ratio of 0%, 5%, 10%, and 15% to investigate the effect of biochar application on the absorption of arsenic in vegetable crops. In addition, reducing the arsenic concentration of irrigation water can slow down the accumulation rate of arsenic concentration in agricultural land. In this study, twelve kinds of materials were selected for the adsorption test of arsenic-rich aqueous solution, and the adsorption capacity of different materials for arsenic was explored, thereby developing a treatment technology for reducing arsenic in irrigation water. The results showed that in addition to hydroponic water, the application of biochar in the other five experimental vegetable crops could increase the yield, and the arsenic content of the edible parts of the five vegetable crops was lower than the white rice inorganic arsenic consumption limit published by the Ministry of Health and Welfare. Mg/kg, showing that arsenic-rich agricultural soils are planted with vegetable crops, and the cumulative concentration of arsenic in edible parts is not high. The arsenic content of water amaranth is much higher than that of the other five vegetable plants. It is recommended that arsenic-rich agricultural land should not plant aquatic food crops as much as possible. The application of biochar has a tendency to increase the arsenic concentration in the roots and shoots of crops. If phyto-contaminated soil is improved by phytoremediation, the application of biochar has the potential to accelerate the rate of arsenic removal. The ultra-deep-burning ceramsite made in Taiwan has a very high adsorption capacity for arsenic in both bulk and powder form. For 0.25-1.0 ppm arsenic aqueous solution, the arsenic removal efficiency can reach more than 99%. The self-prepared calcium chloride modified biochar can also remove more than 60% of arsenic. In the future, it can continue to explore its feasibility as an arsenic removal technology for irrigation water.
Teclu, Daniel Ghebreyo. "Bioremediation of arsenic contaminated groundwater." Thesis, 2008. http://hdl.handle.net/10413/342.
Повний текст джерелаThesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.
Mozumder, Rajib Hassan. "Impacts of pumping on the distribution of arsenic in Bangladesh groundwater." Thesis, 2019. https://doi.org/10.7916/d8-1w98-7737.
Повний текст джерелаWovkulich, Karen. "Laboratory and Field Studies Directed toward Accelerating Arsenic Remediation at a Major US Superfund Site in New Jersey." Thesis, 2011. https://doi.org/10.7916/D87M0FXW.
Повний текст джерела"Potentially harmful trace elements (PHTEs) in the groundwater of Greater Giyani, Limpopo Province, South Africa: possible health implications." Thesis, 2015. http://hdl.handle.net/10210/15089.
Повний текст джерелаMost rural communities in developing countries rely on borehole water as their only source of water. Since borehole water comes from underground, it is often considered pure and clean, but this is frequently not the case. Groundwater contains certain amounts of trace elements that may become deleterious to human health. The objectives of this investigation were to assess the concentration levels of Potential Harmful Trace Elements (PHTEs) and their spatial distribution patterns in borehole water in the Greater Giyani area of Limpopo, South Africa, and the potential human health risks associated with this. The method of research comprised two phases: (I) In the first phase, I assessed the occurrence and distribution patterns of PHTEs in the boreholes of the Giyani area. A total of 29 water samples were collected from boreholes (including 15 community boreholes and 14 primary school boreholes) in the Greater Giyani area during the dry season (July/August 2012), and for comparison another 27 samples (including 15 community boreholes and 12 schools boreholes) from the same localities during the wet season (March 2013). The samples were analysed for the trace elements arsenic (As), cadmium (Cd), chromium (Cr), selenium (Se) and lead (Pb) using the Inductively Coupled Plasma Mass-Spectrometry (ICPMS) technique. In order to assess the groundwater quality, PHTEs concentrations were compared with the South African National Standard of Drinking water (SANS 241-1:2011). (II) In the second phase, I evaluated the geographic variation between PHTEs and associated human health effects. This involved acquisition of data on a total of 100 cancer cases recorded during the period 2011-2014 at Nkhensani Hospital. ArcGIS Spatial analyst tool was used to create thematic maps illustrating spatial distribution of clinical data and arsenic concentrations in boreholes.
Mon-LinChou and 周孟麟. "Impact of Arsenic-Rich Soil and Groundwater Productionof Selected Crops and Remediation Strategies forReducing Arsenic Content in Crops." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/81059740543713963443.
Повний текст джерела國立成功大學
地球科學系
104
Arsenic (As), a toxic substance in the environment, is a major public health concern worldwide. High concentrations of As have also been linked to cancers of the nasal cavity, lung, liver, bladder, kidney, and prostate, and can lead to hypertension and diabetes. Peripheral vascular gangrene, also known as Blackfoot disease (BFD), was first reported in Chianan Plain of southwestern Taiwan in the 1960s. Since 1980, As-rich groundwater has no longer been consumed as drinking water in Taiwan, although it is still widely used for irrigation, aquacultural, and industrial purposes, and hence deserves our continued attention. Rice is the staple food for nearly one-half of world’s population including those living in Taiwan, China, Japan, Korea, and other Asian countries. However, rice uptakes As into grains are much more readily occurred than other cereal crops. The present study geochemically investigates As-rich groundwater, soil, and rice plants from paddy fields in Chianan Plain of southwestern Taiwan, an area which is mainly used for rice cultivation. The stable isotopes of oxygen-18 and deuterium were used to identify different sources of water in a soil layer in rice paddy during the rice growing season in 2014. This study can help us understand that the level of As in rice plants can be affected by the groundwater used for irrigation, type and concentration of As in the soil, and soil properties of paddy fields. In addition, experimental results by means of stable isotopes technique clarified the infiltration of rainfall in the complicated process that can be affected by soil structure, texture, moist and extent of heterogeneity. Results show that the total As concentrations in the groundwater used for irrigation of the sampled paddy fields at Hsuechia, Yichu, and Budai in the Chianan Plain are in the range of 32.9 to 175.7 μg L–1, which is higher than the permissible drink limit (10 μg L–1) recommended by the World Health Organization (WHO) and irrigation limit (50μg L–1) recommended by agricultural authorities of Taiwan. The percentages of As in different parts of the rice plants found in the current study are in the range of 88.3 to 92.8% in roots, 2.8 to 4% in shoots, 1.5 to 5.2% in leaves, 1 to 1.7% in husks, and 0.8 to 1.2% in grains. This study investigated the impacts of various types of irrigation practices with As-contaminated groundwater on the extent of As accumulation within rice plant parts during development and rice crop production at maturity. Three types of irrigation practices were applied to As-rich paddy fields: flooded irrigation, aerobic irrigation, and alternate wetting and drying irrigation (AWDI). Results show that the arsenic concentration in different parts of rice plants varied with growth stage and irrigation practices in both cropping seasons. Lower levels of As in rice were found in AWDI and aerobic irrigation than in flooded irrigation. Different irrigation practices can change the oxidation and reduction conditions of the paddy field, which lead to As release or absorption in the soil, thus influencing the uptake of As by plants. The chemical immobilization of As-rich soil by using ethylenediaminetetraacetic acid ferric sodium salt (EDTA-Fe) and calcium peroxide (CaO2) as stabilizing agents was investigated in Chianan Plain of southwestern Taiwan. The As-rich soil was amended with EDTA-Fe, at the rates of 0, 0.35, 0.7 and 1.4 Mg/ha, or with CaO2, at the rates of 0, 0.38, 0.76 and 1.52 Mg/ha, and grown with radish (Raphanus sativus L.), lettuce (Lactuca sativa), Chinese cabbage (Brassica rapa) and Arden lettuce (Lactuca sativa L.). Results showed that those amended with EDTA-Fe at 0.35 and 0.7 Mg ha−1 can significantly reduce As accumulation in vegetables. Moreover, the uptake of As in vegetables decreased more in soil amended with CaO2 relative to that amended with EDTA-Fe. As indicated, applications of EDTA-Fe at the rate of 0.7 Mg ha−1 and CaO2 at the rate of 1.52 Mg ha−1 can obtain optimal effect on suppressing As uptake by vegetables. Present study aimed to assess the presence and availability of As in paddy field of the Chianan Plain. Arsenic content was determined in soils and pore water sampled at 5 sampling depths (20, 40, 60, 80, 90 cm) in paddy field. The As concentrations in the experimental field soil varied slightly with sampling depths. Total As concentration positively and significantly (p 〈 0.05) correlated with the soil properties including free Fe (Fed), free Mn (Mnd), amorhous Fe (Feo), amorhous Mn (Mno), cation capacity exchange, and clay content. The sequential extraction of soil As showed that As was mainly fixed by both amorphous and crystalline Fe/Mn oxides, which may be ascribable to that As has a high affinity for Fe/Mn oxides under reduction regime of groundwater. As a consequence, As probably would become soluble due to the usage of groundwater and the change of redox regime. In addition, coarse texture of study soil, the flow path of irrigation water, and the gravity impact are factors affecting As movement in the soil layers. The soil As was concentrated on the surface soil and gradually decreased with soil depth. Therefore, total As in subsoils was lower than topsoil because As was adsorbed and accumulated by abundant Fe/Mn oxides in surface soil after irrigation. Based on the measured deuterium and oxygen-18 in soil water, rainwater and groundwater in the paddy field of the Chianan Plain of southwestern Taiwan, in the wet season, the relationship between δD and δ18O in soil water and groundwater recharge after typhoon rainfall (event water) was investigated in the present study. The soil water at different depths before and after event water varied in hydrogen and oxygen isotope ratios. The top soil layer (〈 30 cm depth) had more depleted isotopic compositions as a result of the higher rate of evaporation. Similar soil water isotope composition profiles were observed in shallow soil layers. More depleted fractions of isotopes were found in groundwater as those in rainwater, suggesting that the groundwater primarily came from the rainwater. However, the isotope compositions of hydrogen and oxygen in groundwater is still slightly deviated from the local meteoric water line in southwestern Taiwan. The proposed conceptual model for the interaction among soil, plant and arsenic in the study area can help understand the mechanism that arsenic was released in the subsurface environment. The remedial measure and strategy for reducing arsenic content in selected crops is also proposed in this research.
Sun, Jing. "Developing Improved Strategies of Remediating Arsenic Contaminated Aquifers." Thesis, 2015. https://doi.org/10.7916/D8D50MPW.
Повний текст джерелаHasnat, Mohammad Abul. "Assessment of arsenic mitigation options; adverse pregnancy outcomes due to chronic arsenic exposure; and the impact of nutritional status on development of arsenicosis in Bangladesh." Phd thesis, 2005. http://hdl.handle.net/1885/150925.
Повний текст джерелаMurshed, Rubaiul. "A study on the public health management of arsenic in Bangladesh." Master's thesis, 2002. http://hdl.handle.net/1885/148616.
Повний текст джерелаMihajlov, Ivan. "The vulnerability of low-arsenic aquifers in Bangladesh: a multi-scale geochemical and hydrologic approach." Thesis, 2014. https://doi.org/10.7916/D8K35RR6.
Повний текст джерелаLokuge, Kamalini. "An investigation of the impact of arsenic mitigation on disease burden in Bangladesh, and a randomised controlled trial of selected interventions and their impact on childhood diarrhoeal disease." Phd thesis, 2004. http://hdl.handle.net/1885/151400.
Повний текст джерелаMudzielwana, Rabelani. "Synthesis and potential application of Fe3+/Mn2+ bimetal and hexadecyltrimethylammonium bromide (HDTMA-Br) modified clayey soils for arsenic removal in groundwater." Thesis, 2019. http://hdl.handle.net/11602/1288.
Повний текст джерелаDepartment of Ecology and Resource Management
The presence of arsenic in groundwater has drawn worldwide attention from researchers and public health officials due to its effects on human health such as, cancer, skin thickening, neurological disorders, muscular weakness, loss of appetite and nausea. World Health Organisation (WHO) has set the limit of 10 μg/L for arsenic in drinking water in trying to reduce the effects of arsenic. This was further adopted by South African National Standard (SANS). The present study aims at evaluating arsenic concentration in selected groundwater sources around Greater Giyani Municipality in Limpopo Province and further synthesize clay based adsorbents for arsenic removal using Fe3+ and Mn2+ oxides and hexadecylammonium bromide (HDTMA-Br) cationic surfactant as modifying agents. The first section of the work presented the hydrogeochemical characteristics of groundwater in the Greater Giyani Municipality. The results showed that the pH of the samples ranges from neutral to weakly alkaline. The dominance of major anionic and cationic species was found to be in the order: HCO3 ->Cl->SO4 2->NO3 - and Na+>Mg2+>Ca2+>K+>Si4+, respectively. Hydrogeochemical facies identified in the study area include CaHCO3 (90%) and mixed CaNaHCO3 (10%) which shows the dominance of water-rock interaction. About 60% of the tested samples contains arsenic concentration above 10 μg/L as recommended by SANS and WHO. Concentration of arsenic was found to be ranging between 0.1 to 172.53 μg/L with the average of 32.21 μg/L. In the second part of this work, arsenic removal efficiency of locally available smectite rich and kaolin clay was evaluated. Results showed that the percentage As(V) removal by kaolin clay was optimum at pH 2 while the percentage As(III) removal was greater than 60% at pH 2 to 12. For smectite rich clay soils, the percentage of As(III) and As(V) removal was found to be optimum at pH between 6 and 8. The adsorption isotherm data for As(III) and As(V) removal by both clays fitted better to Freundlich isotherm. Adsorption of both species of arsenic onto the clay mineral occurred via electrostatic attraction and ion exchange mechanisms. Both clay soils could be regenerated twice using Na2CO3 as a regenerant. Kaolin clay showed a better performance and was selected for further modification. In the third section of this work, Fe-Mn bimetal oxide modified kaolin clay was successfully synthesized by precipitating Fe3+ and Mn2+ metal oxides to the interlayer surface of kaolin clay. Modification of kaolin clay increased the surface area from 19.2 m2/g to 29.8 m2/g and further v decreased the pore diameter from 9.54 to 8.5 nm. The adsorption data fitted to the pseudo second order of reaction kinetics indicating that adsorption of As(III) and As(V) occurred via chemisorption. The adsorption isotherm data was described by Langmuir isotherm models showing a maximum As(III) and As(V) adsorption capacities of 2.16 and 1.56 mg/g, respectively at a temperature of 289 K. Synthesized adsorbent was successfully reused for 6 adsorptiondesorption cycles using K2SO4 as a regenerant. Column experiments showed that maximum breakthrough volume of ≈2 L could be treated after 6 hours using 5 g adsorbent dosage. Furthermore, the concentration of Fe and Mn were within the WHO permissible limit. In the fourth part of the work kaolin clay was functionalized with hexadecyltrimethylamonium bromide (HDTMA-Br) cationic surfactant and its application in arsenic removal from groundwater was investigated. The results revealed that adsorption of As(III) and As(V) is optimum at pH range 4-8. The maximum As(III) and As(V) adsorption capacities were found 2.33 and 2.88 mg/g, respectively after 60 min contact time. Pseudo first order model of reaction kinetics described the adsorption data for As(V) better while pseudo second order model described As(III) adsorption data. The adsorption isotherm data for As(III) and As(V) fitted well to Langmuir model indicating that adsorption of both species occurred on a mono-layered surface. Adsorption thermodynamics model revealed that adsorption of As(III) and As(V) was spontaneous and exothermic. The As(III)/As(V) adsorption mechanism was ascribed to electrostatic attraction and ion exchange. The regeneration study showed that synthesized adsorbent can be used for up to 5 times. In the firth part of the work inorgano-organo modified kaolin clay was successfully synthesized through intercalation of Fe3+ and Mn2+ metal oxides and HDTMA-Br surfactant onto the interlayers of the clay mineral. The batch experiments showed that As(III) removal was optimum at pH range of 4-6, while the As(V) removal was optimum at pH range 4-8. The adsorption data for both species of arsenic showed a better fit to pseudo second order of reaction kinetics which suggest that the dominant mechanism of adsorption was chemisorption. The isotherm studies showed better fit to Langmuir isotherm model as compared to Freundlich model. The maximum adsorption capacity As(III) and As(V) at room temperature as determined by Langmuir model were found to be 7.99 mg/g and 7.32 mg/g, respectively. The thermodynamic studies for sorption of As(III) and As(V) showed negative value of ΔGᴼ and ΔHᴼ indicating that adsorption process occurred spontaneously and is exothermic in nature. The regeneration study showed that the vi inorgano-organo modified kaolin clay can be reused for up 7 adsorption-regeneration cycles using 0.01 M HCl as a regenerant. Thomas kinetic model and Yoon-Nelson model showed that the rate of adsorption increases with increasing flow rate and initial concentration and decreases with increasing of the bed mass. In conclusions, adsorbents synthesized from this work showed a better performance as compared to other adsorbents available in the literature. Among the synthesized adsorbents, inorgano-organo modified clay showed highest adsorption capacity as compared to surfactant functionalized and Fe-Mn bimetal oxides modified kaolin clay. However, all adsorbents were recommended for use in arsenic remediation from groundwater. The following recommendations were made following the findings from this study: 1) routine monitoring of arsenic in groundwater of Greater Giyani Municipality, 2) evaluating the possible link between arsenic exposure and arsenic related diseases within Giyani in order to find the extent of the problem in order to establish the population at risk, 3) The toxicity assessment for HDTMA-Br modified kaolin clay should be carried out, 4) Materials developed in the present study should be modeled and tested at the point of use for arsenic removal, and lastly, 5) this study further encourage the development of other arsenic removal materials that can be used at household level.
NRF