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1
Zhang, Shuang, e Noah J. Planavsky. "Revisiting groundwater carbon fluxes to the ocean with implications for the carbon cycle". Geology 48, n. 1 (13 novembre 2019): 67–71. http://dx.doi.org/10.1130/g46408.1.
Testo completoAbstract (sommario):
Abstract Compared with riverine systems, the influence of groundwater on the global carbon cycle has remained underexplored. Here, we provide a new estimate of the bicarbonate fluxes from fresh groundwater to the ocean by coupling a statistical and hydrological analysis of groundwater and river samples across the contiguous United States with a study of global groundwater characteristics. We find that the mean concentration ([]) in groundwaters exceeds that in surface rivers by a factor of 2–3 throughout the contiguous United States. Based on estimates of fresh groundwater discharge to the ocean and scaling up our estimated mean [] in groundwaters from the United States and around the world, we arrived at a mean global flux from groundwaters ranging from 7.4 × 1012 (25th percentile)–1.8 × 1013 mol/yr (75th percentile) to 2.8 × 1013–8.3 × 1013 mol/yr, which is 22%–237% of the global flux from river systems, respectively. We also estimated that the global carbon flux derived from subsurface silicate weathering could be comparable to 32%–351% that from surficial silicate weathering, depending on groundwater discharge rates. Despite large uncertainties due to data limitation, this study highlights that groundwater weathering could be an important carbon sink in both the short- and long-term carbon cycle. Therefore, additional work on groundwaters is needed to develop a well-constrained view of the global carbon cycle.
2
Dong, Yihui, Jiale Li, Zhanxue Sun, Evgeniya Soldatova e Jinjing Zan. "Bacterial diversity and community structure in nitrate-contaminated shallow groundwater in the Poyang Lake basin, China". E3S Web of Conferences 98 (2019): 01012. http://dx.doi.org/10.1051/e3sconf/20199801012.
Testo completoAbstract (sommario):
The Poyang Lake basin in the Jiangxi province of China has been exposed to nitrate pollution caused by irrigation practices, leading to high groundwater nitrate concentration. Eight groundwater samples were collected from shallow wells for hydrochemical, bacterial diversity, and community structure analysis in November 2017. Shallow groundwaters of the basin are weakly acid and in an oxidizing state, with EC ranging from 87.6 to 279.5 µS/cm and TDS varying between 53 to 344 mg/L and averaging of 164 mg/L. The NO3-N form is the dominant nitrogen species in groundwater, with сoncentrations of NO3-N, NO2-N and NH4-N ranging between 2.5 to 164 mg/L, 0.01 to 0.10 mg/L, <0.01 to 0.08 mg/L, respectively. Groundwater communities are dominated by actinobacteria, alphaproteobacterial, gammaproteobacteria and betaproteobacteria both in high- and low-nitrate groundwaters. The results of a 16S rRNA gene clone library indicate that the bacterial community structure of the high-nitrate groundwater is different from that of the low-nitrate groundwater. The bacterial populations Denitratisoma and Sulfuritalea detected in low-nitrate groundwater suggest that these bacteria are capable of denitrification in anaerobic groundwater environment. Bacterial populations Flavobacteria and Cytophagia in high-nitrate groundwater are common in the s wetlands examined and likely capable of nitrification.
3
Kasem, Alaa M., Zhifang Xu, Hao Jiang, Wenjing Liu, Jiangyi Zhang e Ahmed M. Nosair. "Nitrate Source and Transformation in Groundwater under Urban and Agricultural Arid Environment in the Southeastern Nile Delta, Egypt". Water 16, n. 1 (20 dicembre 2023): 22. http://dx.doi.org/10.3390/w16010022.
Testo completoAbstract (sommario):
With the intensification of human activities, nitrate pollutants in groundwater are receiving increasing attention worldwide. Especially in the arid Nile Delta of Egypt, groundwater is one of the most valuable water resources in the region. Identifying the source of nitrate in groundwater with strong human disturbances is important to effective water resource management. This paper examined the stable isotopes (δ15N/δ18O-NO3 and δ2H/δ18O-H2O) and the hydrogeochemical parameters of the shallow groundwaters in the arid southeast of the Nile Delta to assess the potential sources and transformation processes of nitrate under severe urban and agricultural activities. The results revealed that the groundwaters were recharged by the Nile River. Meanwhile, the infiltration of irrigation water occurred in the west, while the mixing with the deep groundwater occurred in the east regions of the study area. The TDS, SO42−, NO3−, and Mn2+ concentrations of groundwaters (n = 55) exceeded the WHO permissible limit with 34.6%, 23.6%, 23.6%, and 65.5%, respectively. The NO3− concentrations in the shallow groundwaters ranged from 0.42 mg/L to 652 mg/L, and the higher levels were observed in the middle region of the study area where the unconfined condition prevailed. It extended to the deep groundwater and eastward of the study area in the groundwater flow direction. The δ15N-NO3 and δ18O-NO3 values suggested that the groundwater NO3− in the west and east regions of semi-confined condition were largely from the nitrification of soil organic nitrogen (SON) and chemical fertilizer (CF). In contrast, wastewater input (e.g., domestic sewage and unlined drains) and prevalent denitrification were identified in the middle region. The denitrification might be tightly coupled with the biogeochemical cycling of manganese. This study provides the first report on the groundwater NO3− dynamics in the Nile Delta, which generated valuable clues for effective water resource management in the arid region.
4
Taşan, Mehmet, Yusuf Demir e Sevda Taşan. "Groundwater quality assessment using principal component analysis and hierarchical cluster analysis in Alaçam, Turkey". Water Supply 22, n. 3 (17 novembre 2021): 3431–47. http://dx.doi.org/10.2166/ws.2021.390.
Testo completoAbstract (sommario):
Abstract This study assessed groundwater quality in Alaçam, where irrigations are performed solely with groundwaters and samples were taken from 35 groundwater wells at pre and post irrigation seasons in 2014. Samples were analyzed for 18 water quality parameters. SAR, RSC and %Na values were calculated to examine the suitability of groundwater for irrigation. Hierarchical cluster analysis and principal component analysis were used to assess the groundwater quality parameters. The average EC value of groundwater in the pre-irrigation period was 1.21 dS/m and 1.30 dS/m after irrigation in the study area. It was determined that there were problems in two wells pre-irrigation and one well post-irrigation in terms of RSC, while there was no problem in the wells in terms of SAR. Piper diagram and cluster analysis showed that most groundwaters had CaHCO3 type water characteristics and only 3% had NaCl- as the predominant type. Seawater intrusion was identified as the primary factor influencing groundwater quality. Multivariate statistical analyses to evaluate polluting sources revealed that groundwater quality is affected by seawater intrusion, ion exchange, mineral dissolution and anthropogenic factors. The use of multivariate statistical methods and geographic information systems to manage water resources will be beneficial for both planners and decision-makers.
5
Craig, D., e L. M. Johnston. "Acid Precipitation and Groundwater Chemistry at the Turkey Lakes Watershed". Canadian Journal of Fisheries and Aquatic Sciences 45, S1 (19 dicembre 1988): s59—s65. http://dx.doi.org/10.1139/f88-267.
Testo completoAbstract (sommario):
To determine correctly the response of a basin to various acid loading events, the groundwater hydrology must be considered as a function of the basin stratigraphy and mineralogy. Groundwaters in the Turkey Lakes Watershed are well buffered and in general provide a reservoir of alkalinity for surface waters in the basin. The groundwater chemistry is dominated by the weathering of carbonates present in the tills. Groundwater can follow a variety of pathways through the subsurface. These pathways can have very different flow rates and groundwater chemistry. As a result of this the influence of groundwater on surface water is highly site specific.
6
Qian, Yong, Shijun Zhen, Chen Yue e Xiangxiang Cui. "Distribution and Origins of Hardness in Shallow and Deep Groundwaters of the Hebei Plain, China". Water 16, n. 2 (17 gennaio 2024): 310. http://dx.doi.org/10.3390/w16020310.
Testo completoAbstract (sommario):
Elevated hardness concentrations in groundwater have become a noteworthy concern in recent decades because long-term drinking of groundwater with high levels of hardness is an important factor resulting in chronic kidney diseases. In this study, the distribution and origins of groundwater total hardness (TH) in various sub-plains and different land-use areas of the Hebei Plain (HBP) were investigated. A total of 445 groundwater samples in the HBP were collected once in 2021, and twelve chemical parameters, including TH in groundwater, were analyzed. Results showed that TH-rich (>450 mg/L) shallow groundwater in both the central and littoral plains was more than twice that in the Piedmont plain. Similarly, TH-rich deep groundwater accounted for about 18% in the central plain but was negligible in the Piedmont plain. In the Piedmont plain, TH-rich shallow groundwater in urban areas was twice or more than in other land use types. By contrast, both TH-rich shallow and deep groundwaters in agricultural areas in the central plain were higher than those in rural areas. This was opposite to TH-rich shallow groundwater in the littoral plain. In the Piedmont plain, TH-rich shallow groundwater was mainly attributed to water-rock interaction, groundwater over-extraction, and the infiltration of domestic sewage and animal waste. In the central plain, both TH-rich shallow and deep groundwaters likely ascribed to the evaporite dissolution and seawater intrusion. By contrast, the leaching of agricultural fertilizers resulting in the dissolution of Ca-rich and Mg-rich minerals in the vadose zone was mainly responsible for the occurrence of TH-rich shallow groundwater in the littoral plain. Therefore, in order to limit elevated hardness concentrations in groundwater in the HBP, limiting shallow groundwater extraction and strengthening the supervision of the domestic sewage and animal waste in the Piedmont plain are recommended. Besides, restricting the use of nitrogenous fertilizers in the littoral plain is also recommended.
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Mamand, Bruska, e Dana Mawlood. "Using Tritium Isotope in Groundwater to Estimate the Reservoir Capacity at Erbil, Northern Iraq". Iraqi Geological Journal 56, n. 2D (31 ottobre 2023): 245–57. http://dx.doi.org/10.46717/igj.56.2d.19ms-2023-10-25.
Testo completoAbstract (sommario):
Tritium is a radioactive isotope of hydrogen in water molecule can be applied in tracer studies to estimate water residence time. The tritium values of the groundwater in Erbil and the reservoir's capacity were the main subjects of this investigation. Three sub-basins, including, Kapran (720 km2), Central (1315 km2), and Bashtapa (625 km2) constructs Erbil City's groundwater basin. 27 groundwater samples from three sub-basins were taken for oxygen-18, tritium analysis and measurement of electrical conductivity. Tritium values divided the groundwater reservoirs into three possible groups: pre-bomb groundwaters that has ages older than 70 years due to lower tritium values, contaminated groundwater and mixture between young and old groundwaters. It is adequate to suppose that there were several substantial subsurface retention reservoirs in Dashty-Hawler basin. For instance, if two wells from the Kapan sub-basin were used as a point of reference, well No. 1 in Kalak region would have a tritium value of 1.7 ± 0.72 TU having groundwater that was approximately 16.2 years old. In contrast, the well No. 6 at Grd-Jutyar has a lower tritium value equal to 0.72 ± 0.68 TU indicating a greater residence time of 31.6 years. These two wells have differing reservoir sizes, and well No. 6 has a longer retention basin to store groundwater than well No. 1 According to these findings, younger groundwater and smaller retention basins were indicated by greater tritium levels, whereas older groundwater and larger retention basins were noted by lower tritium levels.
8
Liu, Chunyan, Qinxuan Hou, Yetao Chen e Guanxing Huang. "Hydrogeochemical Characteristics and Groundwater Quality in a Coastal Urbanized Area, South China: Impact of Land Use". Water 14, n. 24 (19 dicembre 2022): 4131. http://dx.doi.org/10.3390/w14244131.
Testo completoAbstract (sommario):
Land use transformation accompanied with various human activities affects groundwater chemistry and quality globally, especially in coastal urbanized areas because of complex human activities. This study investigated the impact of land use on groundwater chemistry and quality in a coastal alluvial aquifer (CAA) of the Pearl River Delta where urbanization continues. A fuzzy synthetic evaluation method was used to evaluate the groundwater quality. Besides, factors controlling groundwater chemistry and quality in the CAA were discussed by using a principal components analysis (PCA). Nearly 150 groundwater samples were collected. All samples were filtered on-site and stored at 4 °C until the laboratory procedures could be performed. Nineteen chemical parameters including pH, dissolved oxygen, redox potential, total dissolved solids, K+, Na+, Ca2+, Mg2+, NH4+, HCO3−, NO3−, SO42−, Cl−, I−, NO2−, Pb, Mn, Fe, and As were analyzed. Results show that groundwater chemistry in the CAA was dominated by Ca-HCO3 and Ca·Na-HCO3 facies. In addition, groundwater with NO3 facies was also present because of more intensive human activities. In the CAA, 61.8% of groundwaters were fit for drinking, and 10.7% of groundwaters were undrinkable but fit for irrigation, whereas 27.5% of groundwaters were unfit for any purpose. Poor-quality groundwaters in urban and agricultural areas were 1.1–1.2 times those in peri-urban areas, but absent in the remaining area. Groundwater chemistry and quality in the CAA was mainly controlled by five factors according to the PCA. Factor 1 is the release of salt and NH4+ from marine sediments, and the infiltration of domestic and septic sewage. Factor 2 is agricultural activities related to the irrigation of river water, and the use of chemical fertilizers. Factor 3 is the industrial pollution related to heavy metals and acid deposition. Factor 4 is the input of anthropogenic reducing sewage inducing the reductive dissolution of As-loaded Fe minerals and denitrification. Factor 5 is the I− contamination from both of geogenic and anthropogenic sources. Therefore, in order to protect groundwater quality in coastal urbanized areas, repairing old sewer systems in urban areas, building sewer systems in peri-urban areas, limiting sewage irrigation and the amount of chemical fertilizers application in agricultural areas, as well as strengthening the supervision of the industrial exhaust gas discharge in urban and peri-urban areas are recommended.
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Sovann, C., e D. A. Polya. "Improved groundwater geogenic arsenic hazard map for Cambodia". Environmental Chemistry 11, n. 5 (2014): 595. http://dx.doi.org/10.1071/en14006.
Testo completoAbstract (sommario):
Environmental context Groundwater arsenic is a major environmental risk to human health in many regions of the world, including Cambodia where groundwater is often used for drinking water. We present data for hitherto poorly sampled regions in Cambodia, notably around Tonle Sap and in the coastal provinces, and provide a geo-statistical model of arsenic in shallow groundwater for the whole country. Abstract Arsenic is a known environmental chemical hazard in shallow groundwaters of Cambodia and is increasingly recognised as a major problem for public health. Notwithstanding this, accurate arsenic data are not available for many wells in potentially arsenic-prone areas, particularly around the Tonle Sap Great Lake (TSL) and in the coastal provinces (CP). We present here new data for shallow groundwater (16–120-m depth) arsenic in the TSL and CP regions as well as an improved regression-kriging (RK) based groundwater arsenic hazard map for the whole country. High arsenic levels (up to 100μgL–1) were found in shallow groundwaters from the TSL and CP regions of Cambodia, but despite strong compositional similarities (near neutral, reducing, Na-Mg-Ca-HCO3 dominated) with high arsenic level groundwaters near the Mekong and Bassac rivers, groundwater arsenic levels in both the TSL and CP regions were most commonly low (interquartile range 0.09–1.2μgL–1). The RK geostatistical model was highly successful, accounting for over 50% of the observed variation in arsenic concentrations countrywide and represents a potentially useful tool for policymakers and those responsible and with the interest and authority to prepare arsenic mitigation and safe water supply plans.
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Rusiñol, Marta. "Waterborne viruses in urban groundwater environments". PLOS Water 2, n. 8 (17 agosto 2023): e0000168. http://dx.doi.org/10.1371/journal.pwat.0000168.
Testo completoAbstract (sommario):
The proportion of global population using urban aquifers as drinking water sources increases every year and indeed the groundwater quality is not monitored adequately. Although norovirus has been identified as the first cause of groundwater-related outbreaks, the surveillance of waterborne viruses has been rather neglected. From ageing or disrupted sewer systems, occasional sewer discharges (e.g. combined sewer overflows, storm runoff), to poorly managed reclaimed water infiltration practices, multiple are the pathways that cause groundwater quality deterioration. This study revises the main viral contamination sources and the factors affecting viral contamination of groundwater bodies in terms of transport, inactivation, and survival of the viral particles. It also summarizes the methods used for those reporting the presence of human viruses in urban groundwaters. A total of 36 articles have been included in the method survey spanning a period of 24 years (1999–2022). There is a need of systematic monitoring considering representative set of waterborne pathogens. The evaluation of the presence of human adenovirus seems a useful tool to predict the presence of other waterborne pathogens in groundwater. Large volume sampling methods, but also new passive sampling methodologies applied to groundwater, coupled to target massive sequencing approaches may elucidate the range of pathogens capable of contaminating urban groundwaters for further evaluation of risk.
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Liu, Ji Lai, Tian Ming Huang e Jie Li. "Groundwater Recharge Environments and Hydrogeochemical Evolution in Beijing, China: Multi-Tracer Approach". Advanced Materials Research 518-523 (maggio 2012): 3647–51. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.3647.
Testo completoAbstract (sommario):
The groundwater recharge environments and hydrogeochemical characteristics in Beijing were investigated using a combination of chemical indicators, stable isotopes, and radiocarbon dating. There are two distinct zones for those groundwaters: modern water (1000 a) are depleted, which implies that the palaeowaters were recharged in relatively cold climate. The TDS for all groundwater samples range from 312 to 914 mg/L. Groundwaters are supersaturated with respect to calcite and the δ13C value is stable (around -13‰), which suggests dissolution of calcite is limited. Dissolution of halite, sulfate and carbonate and exchange of cations are main processes of water chemistry. The results have important implications for groundwater management in Beijing, where a certain proportion of the unrenewable water has been mined.
12
Haria, A. H., e P. Shand. "Evidence for deep sub-surface flow routing in forested upland Wales: implications for contaminant transport and stream flow generation". Hydrology and Earth System Sciences 8, n. 3 (30 giugno 2004): 334–44. http://dx.doi.org/10.5194/hess-8-334-2004.
Testo completoAbstract (sommario):
Abstract. Upland streamflow generation has traditionally been modelled as a simple rainfall-runoff mechanism. However, recent hydrochemical studies conducted in upland Wales have highlighted the potentially important role of bedrock groundwater in streamflow generation processes. To investigate these processes, a detailed and novel field study was established in the riparian zone and lower hillslopes of the Hafren catchment at Plynlimon, mid-Wales. Results from this study showed groundwater near the river behaving in a complex and most likely confined manner within depth-specific horizons. Rapid responses to rainfall in all boreholes at the study site indicated rapid recharge pathways further upslope. The different flow pathways and travel times influenced the chemical character of groundwaters with depth. Groundwaters were shown to discharge into the stream from the fractured bedrock. A lateral rapid flow horizon was also identified as a fast flow pathway immediately below the soils. This highlighted a mechanism whereby rising groundwater may pick up chemical constituents from the lower soils and transfer them quickly to the stream channel. Restrictions in this horizon resulted in groundwater upwelling into the soils at some locations indicating soil water to be sourced from both rising groundwater and rainfall. The role of bedrock groundwater in upland streamflow generation is far more complicated than previously considered, particularly with respect to residence times and flow pathways. Hence, water quality models in upland catchments that do not take account of the bedrock geology and the groundwater interactions therein will be seriously flawed. Keywords: bedrock, groundwater, Hafren, hillslope hydrology, Plynlimon, recharge, soil water, streamflow generation
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Guggenmos, M. R., B. M. Jackson e C. J. Daughney. "Investigation of groundwater-surface water interaction using hydrochemical sampling with high temporal resolution, Mangatarere catchment, New Zealand". Hydrology and Earth System Sciences Discussions 8, n. 6 (21 novembre 2011): 10225–73. http://dx.doi.org/10.5194/hessd-8-10225-2011.
Testo completoAbstract (sommario):
Abstract. The interaction between groundwater and surface water is dynamic and is known to show considerable spatial and temporal variability. Generally hydrological studies that investigate this interaction are conducted at weekly to yearly timescales and inadvertently lose information contained at the neglected shorter timescales. This paper utilises high resolution physical and chemical measurements to investigate the groundwater and surface water interactions of the small temperate Mangatarere Stream in New Zealand. Continuous electrical conductivity, water temperature and stage measurements were obtained at two surface water gauging stations and one groundwater station, along with one week of intensive hydrochemical grab sampling. A second groundwater gauging station provided limited additional data. The downstream reach of the Mangatarere Stream received significant base flow from neighbouring groundwaters which provided cool Na+-Cl− type waters, high in TDS and NO−3 concentrations. This reach also lost water to underlying groundwaters during an extended dry period when precipitation and regional groundwater stage were low. The upstream groundwater station received recharge primarily from precipitation as indicated by a Na+-Cl−-NO−3 signature, the result of precipitation passage through the soil-water zone. However, river recharge was also provided to the upstream groundwater station as indicated by the transferral of a diurnal water temperature pattern and dilute Na+-Ca2+-Mg2+-HCO3−-Cl− signature. Results obtained from the Mangatarere catchment confirm the temporal complexities of groundwater and surface water interaction and highlight the benefits of multiple investigative approaches and the importance of high frequency hydrochemical sampling and monitoring for process understanding.
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Lam, A., D. Karssenberg, B. J. J. M. van den Hurk e M. F. P. Bierkens. "Spatial and temporal connections in groundwater contribution to evaporation". Hydrology and Earth System Sciences Discussions 8, n. 1 (1 febbraio 2011): 1541–68. http://dx.doi.org/10.5194/hessd-8-1541-2011.
Testo completoAbstract (sommario):
Abstract. In climate models, lateral terrestrial water fluxes are usually neglected. We estimated the contribution of vertical and lateral groundwater fluxes to the land surface water budget at a subcontinental scale, by modelling convergence of groundwater and surfacewater fluxes. We present a hydrological model of the entire Danube Basin at 5 km resolution, and use it to show the importance of groundwater for the surface climate. The contribution of groundwater to evaporation is significant, and can be upwards of 30% in summer. We show that this contribution is local by presenting the groundwater travel times and the magnitude of groundwater convergence. Throughout the Danube Basin the lateral fluxes of groundwater are negligible when modelling at this scale and resolution. Also, it is shown that the contribution of groundwater to evaporation has important temporal characteristics. An experiment with the same model shows that a wet episode influences groundwaters contribution to summer evaporation for several years afterwards. This indicates that modelling groundwater flow has the potential to augment the multi-year memory of climate models.
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Guggenmos, M. R., C. J. Daughney, B. M. Jackson e U. Morgenstern. "Regional-scale identification of groundwater-surface water interaction using hydrochemistry and multivariate statistical methods, Wairarapa Valley, New Zealand". Hydrology and Earth System Sciences 15, n. 11 (15 novembre 2011): 3383–98. http://dx.doi.org/10.5194/hess-15-3383-2011.
Testo completoAbstract (sommario):
Abstract. Identifying areas of interaction between groundwater and surface water is crucial for effective environmental management, because this interaction is known to influence water quantity and quality. This paper applies hydrochemistry and multivariate statistics to identify locations and mechanisms of groundwater-surface water interaction in the pastorally dominated Wairarapa Valley, New Zealand. Hierarchical Cluster Analysis (HCA) and Principal Components Analysis (PCA) were conducted using site-specific median values of Ca, Mg, Na, K, HCO3, Cl, SO4 and electrical conductivity from 22 surface water sites and 246 groundwater sites. Surface water and groundwater monitoring sites were grouped together in three of the seven clusters identified by HCA, with the inference made that similarities in hydrochemistry indicate groundwater-surface water interaction. PCA indicated that the clusters were largely differentiated by total dissolved solids concentration, redox condition and ratio of major ions. Shallow aerobic groundwaters, located in close proximity to losing reaches of rivers, were grouped with similar Ca-HCO3 type surface waters, indicating potential recharge to aquifers from these river systems. Groundwaters that displayed a rainfall-recharged chemical signature with higher Na relative to Ca, higher Cl relative to HCO3 and an accumulation of NO3 were grouped with neighbouring surface waters, suggesting the provision of groundwater base flow to these river systems and the transfer of this chemical signature from underlying aquifers. The hydrochemical techniques used in this study did not reveal groundwater-surface water interaction in some parts of the study area, specifically where deep anoxic groundwaters, high in total dissolved solids with a distinct Na-Cl signature, showed no apparent link to surface water. The drivers of hydrochemistry inferred from HCA and PCA are consistent with previous measurements of 18O, water age and excess air. Overall, this study has shown that multivariate statistics can be used as a rapid method to identify groundwater-surface water interaction at a regional scale using existing hydrochemical datasets.
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Guggenmos, M. R., C. J. Daughney, B. M. Jackson e U. Morgenstern. "Regional-scale identification of groundwater-surface water interaction using hydrochemistry and multivariate statistical methods, Wairarapa Valley, New Zealand". Hydrology and Earth System Sciences Discussions 8, n. 4 (6 luglio 2011): 6443–87. http://dx.doi.org/10.5194/hessd-8-6443-2011.
Testo completoAbstract (sommario):
Abstract. Identifying areas of interaction between groundwater and surface water is crucial for effective environmental management, because this interaction is known to influence water quantity and quality. This paper applies hydrochemistry and multivariate statistics to identify locations and mechanisms of groundwater-surface water interaction in the pastorally dominated Wairarapa Valley, New Zealand. Hierarchical Cluster Analysis (HCA) and Principal Components Analysis (PCA) were conducted using site-specific median values of Ca, Mg, Na, K, HCO3, Cl, SO4 and electrical conductivity from 22 surface water sites and 246 groundwater sites. Surface water and groundwater monitoring sites were grouped together in three of the seven clusters identified by HCA, with the inference made that similarities in hydrochemistry indicate groundwater-surface water interaction. PCA indicated that the clusters were largely differentiated by total dissolved solids concentration, redox potential and ratio of major ions. Shallow aerobic groundwaters, located in close proximity to losing reaches of rivers, were grouped with similar Ca-HCO3 type surface waters, indicating potential recharge to aquifers from these river systems. Groundwaters that displayed a rainfall-recharged chemical signature with higher Na relative to Ca, higher Cl relative to HCO3 and an accumulation of NO3 were grouped with neighbouring surface waters, suggesting the provision of groundwater base flow to these river systems and the transfer of this chemical signature from underlying aquifers. The hydrochemical techniques used in this study did not reveal groundwater-surface water interaction in some parts of the study area, specifically where deep anoxic groundwaters, high in total dissolved solids with a distinct Na-Cl signature, showed no apparent link to surface water. The drivers of hydrochemistry inferred from HCA and PCA are consistent with previous measurements of 18O, water age and excess air. Overall, this study has shown that multivariate statistics can be used as a rapid method to identify groundwater-surface water interaction at a regional scale using existing hydrochemical datasets.
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Nanni, Arthur, Ari Roisenberg, Jandyra M. G. Fachel, Gilberto Mesquita e Cristiano Danieli. "Fluoride characterization by principal component analysis in the hydrochemical facies of Serra Geral Aquifer System in Southern Brazil". Anais da Academia Brasileira de Ciências 80, n. 4 (dicembre 2008): 693–701. http://dx.doi.org/10.1590/s0001-37652008000400010.
Testo completoAbstract (sommario):
Principal component analysis is applied to 309 groundwater chemical data information from wells in the Serra Geral Aquifer System. Correlations among seven hydrochemical parameters are statistically examined. A four-component model is suggested and explains 81% of total variance. Component 1 represents calcium-magnesium bicarbonated groundwaters with long time of residence. Component 2 represents sulfated and chlorinated calcium and sodium groundwaters; Component 3 represents sodium bicarbonated groundwaters; and Component 4 is characterized by sodium sulfated with high fluoride facies. The components' spatial distribution shows high fluoride concentration along analyzed tectonic fault system and aligned on northeast direction in other areas, suggesting other hydrogeological fault systems. High fluoride concentration increases according to groundwater pumping depth. The Principal Component Analysis reveals features of the groundwater mixture and individualizes water facies. In this scenery, it can be determined hydrogeological blocks associated with tectonic fault system here introduced.
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Utomo, H., e H. Siswoyo. "Determination of groundwater conservation zones study by considering groundwater recharge changes". IOP Conference Series: Earth and Environmental Science 1311, n. 1 (1 marzo 2024): 012053. http://dx.doi.org/10.1088/1755-1315/1311/1/012053.
Testo completoAbstract (sommario):
Abstract This paper aims to find a new groundwater conservation zone concept in Indonesia by improving groundwater zoning by considering groundwater recharge changes. The previous zoning criteria only used groundwater level decrease and selected groundwater quality parameters. The ideas of this new concept are related to actual conditions, in terms of groundwater recharge changes due to global climate changes that control the precipitation frequency and in terms of land use changes that control groundwater recharge quantity. The changes are dynamically altered due to anthropogenic interactions. Based on Decree No. 31 2018, the groundwater conservation zone is based on three criteria: the decline of the groundwater table, the groundwater’s physical quality, and the apparent effect on the environment. This research will improve the criteria by suggesting some improvements to that approach: firstly, the application of modeling in calculating the groundwater decline rate, secondly the investigation of the effect of recharge decline due to land use change, and lastly to include recommendations on each zone in the groundwater conservation zone. This new concept is expected will revise the previous Decree that according to the consensus approach is not a scientific approach
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Listiyani R.A., T. "HYDROCHEMISTRY OF GROUNDWATER IN GEYER, GROBOGAN PROVINCE, CENTRAL JAVA". KURVATEK 1, n. 2 (23 maggio 2017): 13–19. http://dx.doi.org/10.33579/krvtk.v1i2.230.
Testo completoAbstract (sommario):
The demand of clean water as well as good quality of drinking water in research area puss the author for knowing about groundwater quality in research area. The aim of the research is to understand the hydrochemistry of groundwater in study area, includinghydrochemical processes and the influence of minerals or rocks to groundwater quality. The methods in the research are groundwater and rocks sampling, petrography and also groundwater’s chemical analysis.Result of this study shows that groundwater quality in Geyer area is influenced by minerals and rocks in that place with dissolution and ions exchange would be important processes. Minerals which composed rocks are dominated by calcareous and clay minerals. These minerals supply chemical components such as Ca2+, Mg2+, Na+, Cl-, carbonate and bicarbonate to groundwater. Key words: hydrochemistry, groundwater, hydrochemical process, major ion.
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Shevchenko, O., e V. Dolin. "GROUNDWATER SELF-CLEARING FROM 90SR WITHIN BACKGROUND AREA AND OWING TO ARTIFICIAL CONTAMINATION". Visnyk of Taras Shevchenko National University of Kyiv. Geology, n. 3 (82) (2018): 100–106. http://dx.doi.org/10.17721/1728-2713.82.13.
Testo completoAbstract (sommario):
The main idea of the presented results is the determination of spatial-temporal regularities of 90Sr content in groundwaters within Chornobyl Exclusion Zone. Utilization of formal kinetic regularities (of I order for irreversible process) for monitoring data analyses has been substantiated. Rate constants of groundwater self-clearing from 90Sr in dependence of type of contamination are calculated by iteration method. Graphic interpretation of data has been realized using package for analysis of Microsoft Excel and Statistica software. Self-clearing of groundwaters is carried out owing to three main processes: sorption as function of water containing medium dispercity, dispersion due to water exchange, concentration dilution (dissolving) of radionuclides in specified volume, and physical decay. considered Self-clearing is considered to be an important element both for the security and vulnerability of groundwaters. Data on 90Sr content in groundwater of background areas, in affected zone of radioactive waste storage, zone of groundwater nutrition from cooling pond of Chornobyl NPP, spots of primarily radioactive contamination, and of groundwater secondary contamination owing to well drilling are discussed. Rate constants for groundwater self-clearing from 90Sr are calculated from experimental data both for non-stationary (rapid) and stationary (slow) processes. The “half-decontamination” period (in analogy to half-life) is less than 0.5 year. The rate constant for unstable process two times, and for established one time exceeds the decay constant. The rates of groundwater self-clearing from strontium-90 owing to water exchange and geochemically immobilization are determined. The equilibrium of sorption-desorption within water saturated zone is generally depended on the rate of water exchange and radionuclides concentration in upper stream, i.e. from concentration gradient.
21
Zhu, Bing-Qi, Xiao-Zong Ren e Patrick Rioual. "Is the Groundwater in the Hunshandake Desert (Northern China) of Fossil or Meteoric Water Origin? Isotopic and Hydrogeochemical Evidence". Water 10, n. 11 (25 ottobre 2018): 1515. http://dx.doi.org/10.3390/w10111515.
Testo completoAbstract (sommario):
To gain an insight into the origin of groundwater in the Hunshandake Desert (HSDK), stable and radioactive isotopes and the major ion hydrochemistry of groundwater, as well as other natural waters, were investigated in this desert. The results showed that the groundwaters in the HSDK are freshwater (total dissolved solid (TDS) < 700 mg/L) and are depleted in δ2H and δ18O when compared with the modern precipitation. The major water types are the Ca–HCO3 and Ca/Mg–SO4 waters. No Cl-type and Na-type waters occurred in the study area. The ionic and depleted stable isotopic signals in groundwater, as well as the high values of tritium contents (5–25 TU), indicate that the groundwaters studied here are young but not of fossil and meteoric water origin, i.e., out of control by the modern and palaeo-direct recharge. A clear difference in the isotopic signals are observed between the groundwaters in the north and south parts of the study area, but the signals are similar between the groundwaters in the north HSDK catchment and its neighboring catchment, the Dali Basin. The topographical elevation decreases from the south (1396 m a.s.l.) to the north (1317 m a.s.l.) and the Dali (1226 m a.s.l.). Groundwaters in the north are characterized by lower chloride and TDS concentrations, higher tritium contents, higher deuterium excess, and more depleted values of δ2H and δ18O than those in the south. The spatial distribution pattern of these environmental parameters indicates a discrepancy between the hydraulic gradient of groundwater and the isotopic and hydrochemical gradients of groundwater in the HSDK, suggesting different recharge sources between the two parts in the desert. A combined analysis using the isotopic and physiochemical data of natural waters collected from the Dali Basin and the surrounding mountains was performed to investigate this problem. It indicates that groundwaters in the HSDK Desert are recharged from remote mountain areas (about 150–200 km to the east and southeast) but not from the north neighboring catchment.
22
Rissmann, C. W. F., M. I. Leybourne, C. Benn, J. A. Kidder e L. K. Pearson. "Comparison of groundwater composition from the Monturaqui and Punta Negra Basins, northern Chile: implications for porphyry copper exploration". Geochemistry: Exploration, Environment, Analysis 22, n. 2 (14 febbraio 2022): geochem2021–056. http://dx.doi.org/10.1144/geochem2021-056.
Testo completoAbstract (sommario):
Groundwaters recovered from the Salar de Punta Negra and Monturaqui basins in the Atacama Desert of northern Chile exhibit distinctly different isotopic, major, trace, and porphyry copper elemental compositions related to contrasting morphostructural, geochemical, and hydrodynamic settings. Comparison of these distinct groundwater signatures with groundwaters from known porphyry copper deposits (Salar de Hamburgo and Spence Deposit), can be used to determine if either basin might be prospective for porphyry copper mineralization. Groundwaters within the Punta Negra Basin exhibit geochemical characteristics consistent with other closed basin settings throughout the arid Andes. Elemental and isotopic compositions within the Punta Negra Basin reflect closed basin evaporitic processes consistent with the hyperarid, volcanic setting of the central Andes. Pathfinder metals and isotopic compositions are not consistent with porphyry copper type mineralization as described for groundwaters within the Salar de Hamburgo Basin, and the Spence Deposit. Within the Monturaqui Basin the geochemical composition of groundwaters are characteristic of diffuse hydrothermal activity. Sulfur isotopic composition within the waters of the northern Monturaqui Basin exhibit δ34SCDT isotopic signatures that fall within the range for sulfide mineralization as reported for groundwaters in and around the Spence Deposit and the Salar de Hamburgo. However, porphyry copper related elements within the Monturaqui Basin are impoverished relative to groundwaters of the Spence and Escondida Deposit. Such impoverishment in porphyry related elements, taken in conjunction with enriched δ13CPDB compositions, elevated groundwater temperatures, groundwater compositions dominated by HCO3, SO4, and Si, and the proximity of the Monturaqui Basin to the current magmatic arc are consistent with a volcanic hydrothermal origin. In summary, the groundwater geochemistry of the Monturaqui and Punta Negra Basins are not indicative of porphyry copper-type mineralization.Thematic collection: This article is part of the Hydrochemistry related to exploration and environmental issues collection available at: https://www.lyellcollection.org/cc/hydrochemistry-related-to-exploration-and-environmental-issues
23
Bi, Pan, Lixin Pei, Guanxing Huang, Dongya Han e Jiangmin Song. "Identification of Groundwater Contamination in a Rapidly Urbanized Area on a Regional Scale: A New Approach of Multi-Hydrochemical Evidences". International Journal of Environmental Research and Public Health 18, n. 22 (19 novembre 2021): 12143. http://dx.doi.org/10.3390/ijerph182212143.
Testo completoAbstract (sommario):
Efficient identification of groundwater contamination is a major issue in the context of groundwater use and protection. This study used a new approach of multi-hydrochemical indicators, including the Cl-Br mass ratio, the hydrochemical facies, and the concentrations of nitrate, phosphate, organic contaminants, and Pb in groundwater to identify groundwater contamination in the Pearl River Delta (PRD) where there is large scale urbanization. In addition, the main factors resulting in groundwater contamination in the PRD were also discussed by using socioeconomic data and principal component analysis. Approximately 60% of groundwater sites in the PRD were identified to be contaminated according to the above six indicators. Contaminated groundwaters commonly occur in porous and fissured aquifers but rarely in karst aquifers. Groundwater contamination in porous aquifers is positively correlated with the urbanization level. Similarly, in fissured aquifers, the proportions of contaminated groundwater in urbanized and peri-urban areas were approximately two times that in non-urbanized areas. Groundwater contamination in the PRD was mainly attributed to the infiltration of wastewater from township-village enterprises on a regional scale. In addition, livestock waste was also an important source of groundwater contamination in the PRD. Therefore, in the future, the supervision of the wastewater discharge of township-village enterprises and the waste discharge of livestock should be strengthened to protect against groundwater contamination in the PRD.
24
Kang, Mary, Debra Perrone, Ziming Wang, Scott Jasechko e Melissa M. Rohde. "Base of fresh water, groundwater salinity, and well distribution across California". Proceedings of the National Academy of Sciences 117, n. 51 (9 dicembre 2020): 32302–7. http://dx.doi.org/10.1073/pnas.2015784117.
Testo completoAbstract (sommario):
The depth at which groundwaters transition from fresh to more saline—the “base of fresh water”—is frequently used to determine the stringency and types of measures put in place to manage groundwater and protect it from contamination. Therefore, it is important to understand salinity distributions and compare defined bases of fresh water with salinity distributions and groundwater well depths. Here we analyze two distinct datasets: 1) a large set of total dissolved solids concentration (TDS) measurements (n= 216,754) and 2) groundwater well locations and depths (n= 399,454) across California. We find that 19 to 56% of the groundwater TDS measurements made at depths deeper than defined bases of fresh water pump fresh groundwater (TDS < 2,000 mg/L). Because fresh groundwater is found at depths deeper than the base of fresh water, current policies informed by base of fresh water assessments may not be managing and protecting large volumes of deep fresh groundwater. Furthermore, we find that nearly 4% of existing groundwater wells penetrate defined bases of fresh water, and nearly 16% of wells overlie it by no more than 100 m, evidencing widespread encroachment on the base of fresh water by groundwater users. Consequently, our analysis suggests that groundwater sustainability in California may be poorly safeguarded in some places and that the base-of-fresh-water concept needs to be reconsidered as a means to define and manage groundwater.
25
Huerta, Pedro, Pedro Carrasco-García, Ildefonso Armenteros, Clemente Recio, Javier Carrasco-García e Esther Rodríguez-Jiménez. "TDEM Soundings as a Tool to Determine Seasonal Variations of Groundwater Salinity (Villafáfila Lakes, Spain)". Water 14, n. 15 (2 agosto 2022): 2402. http://dx.doi.org/10.3390/w14152402.
Testo completoAbstract (sommario):
Interaction between groundwaters with different salinities and lakes show seasonal variations driven by changes in precipitation and evapotranspiration. In the vicinity of Villafáfila lakes, local fresh and brackish regional groundwaters feeds the lakes, forming a brine in the lake sediments aquitard. Two TDEM surveys (summer 2019 and winter 2020) were carried out. Five TDEM soundings were acquired at the same location for each survey, forming a profile from the hills to the lake-shore. Simultaneously to the TDEM surveys, electric conductivity of lake water and groundwater was measured. The resistivity boundary between the local fresh (10–35 Ohm/m) and regional brackish groundwater (2–5 Ohm/m) is well marked at 600 m above sea level (masl) below the hills, and at 650 masl below the lowlands surrounding the lakes. During the summer, fresh-brackish groundwater interphase rises due to evaporative pumping occurring in the lowlands. This increases groundwater salinity close to the terrain surface favoring precipitation of halite efflorescences. Annual record of EC in a piezometer confirms the summer ascendant of the brine contained in the lake aquitard. TDEM sounding is fast and simple technique to monitor seasonal variations in fresh-brackish groundwater interphase and to detect possible salinization of consumption wells and environmental changes.
26
Chen, Song, e Herong Gui. "Calculating groundwater mixing ratios in multi-aquifers based on statistical methods: a case study". Water Practice and Technology 16, n. 2 (19 marzo 2021): 621–32. http://dx.doi.org/10.2166/wpt.2021.027.
Testo completoAbstract (sommario):
Abstract Samples of river water and groundwater from Quaternary (QA), sandstone (SA), Taiyuan formation (TA), and Ordovician limestone (OA) aquifers in the Suxian coal-mining district, Anhui Province, China were collected. Their physicochemical properties, and major ion and isotopic compositions were determined. The samples were alkaline, with pH values exceeding 8, and the total dissolved solids concentrations depended on the water source. The δD and δ18O contents were highest in the river water samples and lowest in the SA groundwater. The isotopic characteristics of the QA and OA groundwaters suggest recharge by rainfall and surface water. The isotopic characteristics of river water were controlled mainly by evaporation. Water–rock interactions, the flow rate, and the main water sources were the most important influences on groundwaters in QA, OA, and TA, but the properties of SA groundwater were controlled by static reserves. Two discriminant functions, explaining more than 98.2% of the total variances, indicated that QA, TA, and OA were hydraulically connected. Three groundwater sources were identified as end-members, and a conceptual model was established to calculate water mixing ratios.
27
Polya, D. A., A. G. Gault, N. Diebe, P. Feldman, J. W. Rosenboom, E. Gilligan, D. Fredericks et al. "Arsenic hazard in shallow Cambodian groundwaters". Mineralogical Magazine 69, n. 5 (ottobre 2005): 807–23. http://dx.doi.org/10.1180/0026461056950290.
Testo completoAbstract (sommario):
AbstractOur recent discovery of hazardous concentrations of arsenic in shallow sedimentary aquifers in Cambodia raises the spectre of future deleterious health impacts on a population that, particularly in non-urban areas, extensively use untreated groundwater as a source of drinking water and, in some instances, as irrigation water. We present here small-scale hazard maps for arsenic in shallow Cambodian groundwaters based on >1000 groundwater samples analysed in the Manchester Analytical Geochemistry Unit and elsewhere. Key indicators for hazardous concentrations of arsenic in Cambodian groundwaters include: (1) well depths greater than 16 m; (2) Holocene host sediments; and (3) proximity to major modern channels of the Mekong (and its distributary the Bassac). However, high-arsenic well waters are also commonly found in wells not exhibiting these key characteristics, notably in some shallower Holocene wells, and in wells drilled into older Quaternary and Neogene sediments.It is emphasized that the maps and tables presented are most useful for identifying current regional trends in groundwater arsenic hazard and that their use for predicting arsenic concentrations in individual wells, for example for the purposes of well switching, is not recommended, particularly because of the lack of sufficient data (especially at depths >80 m) and because, as in Bangladesh and West Bengal, there is considerable heterogeneity of groundwater arsenic concentrations on a scale of metres to hundreds of metres. We have insufficient data at this time to determine unequivocally whether or not arsenic concentrations are increasing in shallow Cambodian groundwaters as a result of groundwater-abstraction activities.
28
Chen, Song, e Herong Gui. "The age, distribution, and geochemical characteristics of groundwater in the Ordovician limestone aquifer in the Huaibei coalfield, China". Water Practice and Technology 12, n. 2 (1 giugno 2017): 354–62. http://dx.doi.org/10.2166/wpt.2017.042.
Testo completoAbstract (sommario):
In this study, we collected 22 groundwater samples and supporting measurements from different coal-mining districts in the Huaibei coalfield to examine the age, hydro-chemical characteristics, and evolution of groundwater in the Ordovician limestone aquifer (OA). We determined the groundwater concentrations of major ions, stable isotopes (hydrogen and oxygen) and a radio isotope (14C). All the samples were alkaline in nature, and had pH values between 7.10 and 10.80. The total dissolved solids (TDS) contents varied from 119 to 2,443 mg/l. The concentrations of δD and δ18O in groundwater varied from −64.32‰ to −42.76‰, and from −8.62‰ to −5.40‰, with mean values of −56.38‰ and −7.62‰, respectively. The groundwater at OA is recharged by rainfall or surface water, and, because of either the long residence time or runoff into the aquifer, is influenced by water-rock interactions. The age of the groundwater in the OA ranged from 2,660a to 10,040a, and the groundwaters were youngest and oldest in the Renlou and Yangzhuang coal mines, respectively. Contour diagrams of TDS in groundwater, the groundwater age, and the spatial distribution of the water types indicated that the Renlou and Yangzhuang mines were the recharge and discharge areas, respectively.
29
Setyaningsih, D. L., K. D. Setyawan, D. P. E. Putra e Salahuddin. "Hydrogeological Conceptual Model in the Middle of Randublatung Groundwater Basin". IOP Conference Series: Earth and Environmental Science 926, n. 1 (1 novembre 2021): 012078. http://dx.doi.org/10.1088/1755-1315/926/1/012078.
Testo completoAbstract (sommario):
Abstract Randublatung groundwater basin is one of the groundwaters basins with massive utilization of groundwater pumping. However, the knowledge of the comprehensive hydrogeological system in this groundwater basin is limited, so this research aims to determine a comprehensive hydrogeological conceptual model of the Randublatung groundwater basin. The methodology was conducted by collecting secondary and primary data of deep and shallow wells to evaluate boundaries of pattern and direction of groundwater flow and develop the aquifer system’s geometry. The result shows that the groundwater flow boundaries are Grogol River in the west, Wado River in the East, Bengawan Solo river in the South as a river boundary, and Rembang Mountains in the North as a constant head boundary. Therefore, groundwater flows from the hills area to the Bengawan Solo River and the north as the river’s flow. Based on the log bor evaluation, the aquifer system of the study area consist of an unconfined aquifer with a maximum thickness of 20 m and three layers of confined aquifers with thickness vary between 8 to 60 m. the hydraulic conductivity of the aquifers depends on the aquifer’s lithology range from sand, gravel, limestone, and sandstone. This hydrogeological conceptual model provides essential information for numerical groundwater models in the middle of the Randublatung groundwater basin.
30
Wei, De Jian, e Xin Gui Zhang. "Analysis for the Uncertainty and Changeability of Groundwater Causticity". Applied Mechanics and Materials 130-134 (ottobre 2011): 3788–90. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.3788.
Testo completoAbstract (sommario):
During wet season and dry season, the groundwater quality analysis results of one engineering site in Nanning indicated that the causticity of groundwater mainly included acid causticity (pH value), calcareous causticity (corrosive CO2) and leaching causticity (HCO3-). Though the twice analysis results of water causticity are both moderately corrosion, the types of decomposed corrosion are different. It indicated the uncertainty and changeability of decomposed corrosion. In actual projects, some special ingredients in groundwater, the site natural environment and hydrologic geologic conditions should be considered together to define the groundwater’s causticity. Moreover, the change of site hydrologic geologic conditions caused by the construction should be considered, because this change can also influence the groundwater’s causticity. In addition, the groundwater’s causticity will influence the selection of cement types and the type of cement will influence the type of foundation, then all these will influence the construction cost finally. So, the change of groundwater’s causticity caused by the site hydrologic geologic conditions should be considered at engineering design time.
31
Puspita, T. R., e D. A. Kuncoro. "Groundwater Facies in the South Parts of Tegal-Brebes Groundwater Basin". IOP Conference Series: Earth and Environmental Science 1233, n. 1 (1 agosto 2023): 012010. http://dx.doi.org/10.1088/1755-1315/1233/1/012010.
Testo completoAbstract (sommario):
Abstract The southern part of the Tegal Brebes Groundwater Basin has various rock units originating from the volcanic activity of the Slamet Volcano. The groundwater interacts with these rocks and influences the hydrogeochemical process that may alter its chemical components. The objective of this research is to assess the relationship between groundwater chemistry facies and the rock aquifer. The finding of this research will help us better understand how hydrogeochemical processes work, perform thorough research, and determine the water quality. The groundwater characteristics are determined based on the chemical composition of the water taken from the citizen’s dug wells and springs. These samples were collected to represent a difference in rock’s formation, namely Linggopodo Formation, Tapak, and Slamet Undifferentiated Volcanic Rock. The analysis of the Piper diagram shows that all the samples fall into one facies: the calcium bicarbonate type (Ca-HCO3). The groundwater’s physical and chemical properties in the study area indicate that groundwater quality has not interacted much with lithology and is still greatly influenced by meteoric water. The groundwater facies are dominated by the Ca-HCO3, a characteristic of shallow groundwater and local water flow systems.
32
Jantzen, Carol M., e Cory L. Trivelpiece. "Uranium Dissolution and Geochemical Modeling in Anoxic and Oxic Solutions". MRS Advances 2, n. 13 (2017): 705–10. http://dx.doi.org/10.1557/adv.2017.58.
Testo completoAbstract (sommario):
ABSTRACTHigh Level Waste (HLW) glasses are to be stored in deep geologic repositories around the world. Some potential repository geologies have oxidizing groundwaters while some have reducing or anoxic groundwaters. The differences in the oxidizing potential of the groundwater, expressed as groundwater Eh, which has a profound impact on the release of multivalent species such as iron and uranium from the glass. Static leach testing of monolithic glass samples (ASTM C1220) doped with uranium were performed at 90°C in an Ar glovebox under anoxic and oxic conditions. Tests were performed in both deionized water and in simulated basaltic groundwater that was pre-equilibrated at low Eh. Geochemical modeling of the measured Eh-pH conditions from the oxic and anoxic experiments using Geochemist’s Workbench software, suggested that different colloidal species control the release of uranium species under oxic and anoxic conditions.
33
LEE, J. Y. "Environmental issues of groundwater in Korea: implications for sustainable use". Environmental Conservation 38, n. 1 (marzo 2011): 64–74. http://dx.doi.org/10.1017/s0376892911000087.
Testo completoAbstract (sommario):
SUMMARYGroundwater has been extensively exploited worldwide but is now confronted by a variety of problems, including groundwater depletion and contamination, that threaten its sustainable use as a clean water source. Groundwater is one of the major sources of water for domestic, agricultural and industrial uses, and provides 13% of the total annual water supply in Korea. Annual groundwater use has continuously increased from 2.57 billion m3 in 1994 to 3.72 billion m3 in 2007, of which 48.1% was consumed for domestic purposes. However, due to imprudent groundwater development and inappropriate management, Korea has confronted some critical groundwater problems, including extensive water level decline and quality deterioration caused by petroleum hydrocarbons and chlorinated solvents. Among 193 national groundwater deep-monitoring wells nationwide, 62% showed decreasing water levels over the period 2004–2008. Soil and groundwater contamination by petroleum hydrocarbons was detected at a great number of military bases and public facilities, which drew national attention and complaints. The presence of high levels of radionuclides such as uranium and radon in groundwater has awakened controversy on their health effects. Increasing outbreaks of massive gastroenteritis were attributed to noroviruses in contaminated groundwater, and raised public health concerns. In addition, chlorinated solvents, especially trichloroethylene (TCE), have been frequently found in urban and industrial groundwaters, further adding to the burdens of environmental authorities. Consequently, these groundwater-related environmental issues have forced the Korean government and relevant authorities to urgently devise mitigation plans to secure a sustainable future use of groundwater resources. This paper provides details of the groundwater issues and implications for appropriate development and management.
34
Beden, Neslihan, Nazire Göksu Soydan-Oksal, Sema Arıman e Hayatullah Ahmadzai. "Delineation of a Groundwater Potential Zone Map for the Kızılırmak Delta by Using Remote-Sensing-Based Geospatial and Analytical Hierarchy Processes". Sustainability 15, n. 14 (13 luglio 2023): 10964. http://dx.doi.org/10.3390/su151410964.
Testo completoAbstract (sommario):
Locating prospective groundwater recharge zones is essential for managing and planning groundwater resources. Therefore, spatial modeling of groundwater distribution is a significant undertaking that would aid groundwater’s subsequent conservation and management. The current study employs geographic information systems (GIS) and analytical hierarchy process (AHP) based on multi-criteria analysis to identify groundwater potential zones (GPZ). The AHP technique was utilized to analyze and generate the geo-environmental factor parameters, which included drainage density, lineament density, precipitation, slope, soil texture, land use/land cover, groundwater level, and geology. Each factor is weighted according to its characteristics and effects on water potential in this process. Finally, the weighted overlay method was applied in a GIS environment to gather the weighted variables and locate the map of the GPZ. The proposed GPZ map is divided into four different groundwater potential zones: poor, moderate, high, and very high. Consequently, according to the results, 38% of the basin has very high groundwater potential, 19% has high potential, 39% has moderate potential, and 4% has poor potential from the spatial distribution of the potential regions. Therefore, the study’s conclusions can be used to sustain groundwater resources by identifying areas with high groundwater potential.
35
Orou, Rodrigue Kotchi, Gbombélé Soro, Drissa Tanina Soro, Abou Traoré, Rosine Marie N’guessan Fossou e Nagnin Soro. "Aptitudes À L’agriculture Des Eaux Souterraines Du Departement d’Agboville (Sud-Est De La Côte d’Ivoire)". European Scientific Journal, ESJ 12, n. 21 (29 luglio 2016): 81. http://dx.doi.org/10.19044/esj.2016.v12n21p81.
Testo completoAbstract (sommario):
In the department of Agboville, farmers are interested in the using of groundwater to improve the performance of their crops. But they didn’t know the effects of this water on the crops without. The main objective of this study is to determine the quality of groundwater to prevent the risk of soil alkalinization and salinization in the department of Agboville. Hydrochemical analysis of 28 wells used for irrigation of crops was carried out. The dry residue (RS), the osmotic pressure (π), Sodium Absorption Ratio (SAR), the percentage of sodium exchange (ESP), salinity potential (SP), and the coefficient or the Kelly ratio (RK) were determined. Wilcox diagram was also applied for this study. The results show that groundwater department are soft and lightly mineralized wiht a low salinity. 75% of samples from groundwater haves low salinity and 25% have an average salinity. The values of the Salinity Potential (SP <5), Kelly Ratio (RK <1) and SAR (SAR <10 méq/L) show that all sampled groundwater are good qualities for agriculture. According to Wilcox diagram, groundwaters are excellent quality for agriculutre. The osmotic pressure (𝜋 ), the dry residue (RS) and the conductivity values 75% of the sampled waters are excellent quality and 25% average quality for agriculture. Groundwaters from the department of Agboville have a low risk of alkalizing and can be used in irrigation for most crops.
36
Hernández-Antonio, A., J. Mahlknecht, C. Tamez-Meléndez, J. Ramos-Leal, A. Ramírez-Orozco, R. Parra, N. Ornelas-Soto e C. J. Eastoe. "Groundwater flow processes and mixing in active volcanic systems: the case of Guadalajara (Mexico)". Hydrology and Earth System Sciences 19, n. 9 (24 settembre 2015): 3937–50. http://dx.doi.org/10.5194/hess-19-3937-2015.
Testo completoAbstract (sommario):
Abstract. Groundwater chemistry and isotopic data from 40 production wells in the Atemajac and Toluquilla valleys, located in and around the Guadalajara metropolitan area, were determined to develop a conceptual model of groundwater flow processes and mixing. Stable water isotopes (δ2H, δ18O) were used to trace hydrological processes and tritium (3H) to evaluate the relative contribution of modern water in samples. Multivariate analysis including cluster analysis and principal component analysis were used to elucidate distribution patterns of constituents and factors controlling groundwater chemistry. Based on this analysis, groundwater was classified into four groups: cold groundwater, hydrothermal groundwater, polluted groundwater and mixed groundwater. Cold groundwater is characterized by low temperature, salinity, and Cl and Na concentrations and is predominantly of Na-HCO3-type. It originates as recharge at "La Primavera" caldera and is found predominantly in wells in the upper Atemajac Valley. Hydrothermal groundwater is characterized by high salinity, temperature, Cl, Na and HCO3, and the presence of minor elements such as Li, Mn and F. It is a mixed-HCO3 type found in wells from Toluquilla Valley and represents regional flow circulation through basaltic and andesitic rocks. Polluted groundwater is characterized by elevated nitrate and sulfate concentrations and is usually derived from urban water cycling and subordinately from agricultural return flow. Mixed groundwaters between cold and hydrothermal components are predominantly found in the lower Atemajac Valley. Twenty-seven groundwater samples contain at least a small fraction of modern water. The application of a multivariate mixing model allowed the mixing proportions of hydrothermal fluids, polluted waters and cold groundwater in sampled water to be evaluated. This study will help local water authorities to identify and dimension groundwater contamination, and act accordingly. It may be broadly applicable to other active volcanic systems on Earth.
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Van, Tuc Dang, Quang Khai Ha e Phu Le Vo. "Groundwater resources in Bac Lieu province, Mekong Delta: current groundwater extraction and related issues". IOP Conference Series: Earth and Environmental Science 1170, n. 1 (1 aprile 2023): 012027. http://dx.doi.org/10.1088/1755-1315/1170/1/012027.
Testo completoAbstract (sommario):
Abstract Groundwater in coastal cities is facing with various challenges such as contamination, salinization and land subsidence due to poor management and climate change. This research is aimed to summary groundwater issues such as groundwater quality, salinization and land subsidence in Bac Lieu City, a coastal city of Mekong Delta. A datasets of wells survey, wells logs and groundwater sampling were utilized for the study. The results show that saline groundwaters (TDS> 1.5 g/L) cover 99 and 54% area of shallow aquifers including Holocene, Upper Pleistocene and 48, 93, and 82% area of very deep aquifers like middle Pliocene, lower Pliocene, and upper Miocene, respectively. Fresh groundwater (TDS <1.5 g/L) is mainly found from 75 to 227 m in upper middle Pleistocene, lower Pleistocene and middle Pliocene aquifers. Groundwater extraction amount increases sharply during the last decades which induced groundwater level decline to 15 m below mean sea level (bmsl). The decline of groundwater level is even observed in the non-extracted aquifers suggesting that those aquifers are hydraulically connected. Land subsidence is observed in some groundwater extraction wells. Groundwater chemical data reflects that 73, 53, 28, 21, 18, 16, and 8% of total 120 groundwater samples show the concentrations of hardness, NO3 −, Cl−, TDS, Na+, NO2 −, and NH4 + are greater than those recommended in Vietnam National Technical Regulation on Domestic Water Quality (RDWQ; QCVN 01-1:2018/BYT) suggesting that groundwater in the area should not be used directly for domestic purposes. The occurrence of high Na+, TDS and Cl- concentrations in some groundwater samples may indicate salinization. The observation of high NO3 − is also a strange phenomenon in this area. Finding the sources of NO3 high concentration and salinization are highly recommended for further studies to sustainable practices of groundwater protection and management in the area.
38
Parasha, V. K., e Sunil Kumar Sharma. "Suitability of Groundwater Quality for Irrigational use between Silkanth and Kundgaon, North of River Narmada in the Upper Alluvial Plains of Narmada Valley, District Sehore and Dewas, M.P., India". Oriental Journal of Physical Sciences 2, n. 2 (25 dicembre 2017): 121–28. http://dx.doi.org/10.13005/ojps02.02.12.
Testo completoAbstract (sommario):
Groundwater is one of the earth’s most widely distributed resources and is consistently catering to the requirement of the agricultural irrigation. In the present study, an attempt has been made to understand the hydrochemistry and its agricultural water quality of groundwater between Silkhanth and Kundgaon, North of river Narmada, Madhya Pradesh. During the course of water quality studies of the area, 17 groundwater samples were collected and chemically analysed. Results obtained from water chemistry were used in the determination of different irrigational specifications to appraise the agricultural quality of groundwater. Important specifications like Sodium Adsorption Ratio (SAR) Residual Sodium Carbonate (RSC), Soluble Sodium Percentage (SSP) and Kelly’s Ratio (KR) are used for decisive the appropriateness of groundwater for the agricultural purposes. Result shows that the majority of groundwater belongs to Medium to - High Saline and Low sodium water. As per the magnesium ratio classification, the groundwaters of the study area has no magnesium hazards. Kelly’s ratio shows that majority of groundwater belongs to suitable class. As per the classification based on RSC the groundwater belongs to Safe class. As per the guidelines of Ayers and Westcot, majority of water have slight to moderate toxicity with respect to Nitrate and their use is restricted for semitolerant crops.
39
Wu, Ruohan, Laura A. Richards, Ajmal Roshan e David A. Polya. "Artificial Intelligence Modelling to Support the Groundwater Chemistry-Dependent Selection of Groundwater Arsenic Remediation Approaches in Bangladesh". Water 15, n. 20 (11 ottobre 2023): 3539. http://dx.doi.org/10.3390/w15203539.
Testo completoAbstract (sommario):
Groundwater arsenic (As) still poses a massive public health threat, especially in South Asia, including Bangladesh. The arsenic removal efficiency of various technologies may be strongly dependent on groundwater composition. Previously, others have reported that the molar ratio [Fe]−1.8[P][As], in particular, can usefully predict the potential efficiency of groundwater As removal by widespread sorption/co-precipitation-based remediation systems. Here, we innovatively extended the application of artificial intelligence (AI) machine learning models to predict the geospatial distribution of [Fe]−1.8[P][As] in Bangladesh groundwaters utilizing our analogous AI predictions for groundwater As, Fe, and P. A comparison between the predicted geospatial distribution of groundwater As and [Fe]−1.8[P][As] distinguished high groundwater As areas where (a) sorption/co-precipitation remediation technologies would have the potential to be highly effective in removing As without Fe amendment, as well as from those areas where (b) amendment with Fe (e.g., zero-valent Fe) would be required to promote efficient As removal. The 1 km2 scale of the prediction maps provided a 100-fold improvement in the granularity of previous district-scale non-AI models. AI approaches have the potential to contribute to informing the appropriate selection and amendment of appropriate groundwater contamination remediation strategies where their effectiveness depends on local groundwater chemistry.
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Hartmann, Andreas, Scott Jasechko, Tom Gleeson, Yoshihide Wada, Bartolomé Andreo, Juan Antonio Barberá, Heike Brielmann et al. "Risk of groundwater contamination widely underestimated because of fast flow into aquifers". Proceedings of the National Academy of Sciences 118, n. 20 (10 maggio 2021): e2024492118. http://dx.doi.org/10.1073/pnas.2024492118.
Testo completoAbstract (sommario):
Groundwater pollution threatens human and ecosystem health in many regions around the globe. Fast flow to the groundwater through focused recharge is known to transmit short-lived pollutants into carbonate aquifers, endangering the quality of groundwaters where one quarter of the world’s population lives. However, the large-scale impact of such focused recharge on groundwater quality remains poorly understood. Here, we apply a continental-scale model to quantify the risk of groundwater contamination by degradable pollutants through focused recharge in the carbonate rock regions of Europe, North Africa, and the Middle East. We show that focused recharge is the primary reason for widespread rapid transport of contaminants to the groundwater. Where it occurs, the concentration of pollutants in groundwater recharge that have not yet degraded increases from <1% to around 20 to 50% of their concentrations during infiltration. Assuming realistic application rates, our simulations show that degradable pollutants like glyphosate can exceed their permissible concentrations by 3 to 19 times when reaching the groundwater. Our results are supported by independent estimates of young water fractions at 78 carbonate rock springs over Europe and a dataset of observed glyphosate concentrations in the groundwater. They imply that in times of continuing and increasing industrial and agricultural productivity, focused recharge may result in an underestimated and widespread risk to usable groundwater volumes.
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Ács, Tamás, e Zoltán Simonffy. "A new deterministic method for groundwater mapping using a digital elevation model". Water Supply 13, n. 4 (1 agosto 2013): 1146–53. http://dx.doi.org/10.2166/ws.2013.106.
Testo completoAbstract (sommario):
Accurate knowledge of groundwater levels and flow conditions in the vicinity of groundwater-dependent terrestrial ecosystems (GWDTE-s) is required for identifying groundwater dependency and comparing the present situation with the optimal one, as part of the status assessment of groundwaters according to the EU Water Framework Directive. Geostatistical methods (like kriging or cokriging) may result in an unrealistic groundwater level map if only a few measured data are available. In this paper a new, grid-based, deterministic method (GSGW-model) is introduced. The aim of the model is to calculate groundwater depth within the required accuracy from sparse data of monitoring wells. The basic principle of the GSGW-model is that the groundwater table is a smoothed replica of the ground surface. Hence, changes in the groundwater level between two grid points are calculated as a function of the digital elevation model (DEM) and soil properties. The GSGW-model was tested in the Nyírség region (Hungary). Results were compared with those gained by ordinary kriging and cokriging. It has been concluded that kriging overestimates the groundwater level in the low part of the test area, where wetlands are located, while the maps produced by the GSGW-model are a better fit of the real variability, providing more reliable estimates of groundwater depth in GWDTE-s as well.
42
Živančev, Nevena, Srđan Kovačević, Marija Perović, Aleksandar Čalenić e Milan Dimkić. "Influence of oxic and anoxic groundwater conditions on occurrence of selected agrochemicals". Water Supply 20, n. 2 (5 dicembre 2019): 487–98. http://dx.doi.org/10.2166/ws.2019.178.
Testo completoAbstract (sommario):
Abstract The occurrence and mitigation of selected pesticides and nitrates in surface and groundwater samples from two alluvions in the Republic of Serbia are investigated in this study. The influence of aquifer conditions on the degradation processes of pesticides and nitrates is considered as a potential removal mechanism of compound residues in alluvial groundwater. Nitrate concentration was analyzed in 144 groundwater samples in the Kovin-Dubovac drainage system and 63 samples at the Ključ groundwater source. The occurrence of 15 pesticides was monitored in groundwater in a total of 34 samples in the Kovin-Dubovac area and 14 samples at the Ključ groundwater source. Concentrations of selected pesticides and nitrates were monitored in eight samples from the Danube in the Kovin-Dubovac area and 15 samples from Velika Morava at the Ključ groundwater source. Both selected locations are agricultural areas. Results show that concentrations of nitrates (NO3−) are much higher in oxic groundwater conditions compared with concentrations in typical anoxic conditions. The opposite is the case for the concentration of pesticides that occurred in surface and groundwater samples. These results are very important for a better understanding of the self-purification potential of alluvial aquifers and assessment of aquifer condition influence, especially oxic or anoxic conditions, on the occurrence and mitigation of selected agrochemical residues in groundwaters.
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Iwatake, Kaname, e Akira Ueda. "Geochemical Study on the Annual Variation of Oxygen Isotope and Chemical Composition of Groundwater in the Sho River Alluvium Fan, Toyama, Japan, as an Investigation of Selected Qualitative Aspects of Efficient Utilization of Groundwater Heat". Geosciences 11, n. 8 (23 agosto 2021): 352. http://dx.doi.org/10.3390/geosciences11080352.
Testo completoAbstract (sommario):
Seasonal variations of water temperature, electric conductivity, and oxygen isotope and chemical composition of shallow groundwaters and river waters were determined in the Sho River alluvial fan, western Toyama Prefecture, Japan, to examine groundwater heat utilization for indoor climate control. Samples were collected at 31 sites every 2 months for 1 year and at 11 representative sites monthly. In addition, the results of monthly precipitation amount and oxygen isotope composition of precipitation collected within the region during the same period were also taken into account. The sources of the shallow groundwaters are a mixture of river water and precipitation. The contribution of precipitation to groundwater is generally small along the Sho River but reaches as much as 80% along the Oyabe River and in the south and west of the alluvial fan. Though the origin of the groundwater differs regionally, water temperature is fixed at around 15 °C throughout the year in the northern part of the alluvial fan, and open-type ground source heat pump systems can be used for cooling and heating there, if adequate quantitative aquifer properties (exploitable groundwater amounts) are present.
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Hernández-Antonio, A., J. Mahlknecht, C. Tamez-Meléndez, J. Ramos-Leal, A. Ramírez-Orozco, R. Parra, N. Ornelas-Soto e C. J. Eastoe. "Groundwater flow processes and mixing in active volcanic systems: the case of Guadalajara (Mexico)". Hydrology and Earth System Sciences Discussions 12, n. 2 (3 febbraio 2015): 1599–631. http://dx.doi.org/10.5194/hessd-12-1599-2015.
Testo completoAbstract (sommario):
Abstract. Groundwater chemistry and isotopic data from 40 production wells in the Atemajac and Toluquilla Valleys, located in and around the Guadalajara metropolitan area, were determined to develop a conceptual model of groundwater flow processes and mixing. Multivariate analysis including cluster analysis and principal component analysis were used to elucidate distribution patterns of constituents and factors controlling groundwater chemistry. Based on this analysis, groundwater was classified into four groups: cold groundwater, hydrothermal water, polluted groundwater and mixed groundwater. Cold groundwater is characterized by low temperature, salinity, and Cl and Na concentrations and is predominantly of Na-HCO3 type. It originates as recharge at Primavera caldera and is found predominantly in wells in the upper Atemajac Valley. Hydrothermal water is characterized by high salinity, temperature, Cl, Na, HCO3, and the presence of minor elements such as Li, Mn and F. It is a mixed HCO3 type found in wells from Toluquilla Valley and represents regional flow circulation through basaltic and andesitic rocks. Polluted groundwater is characterized by elevated nitrate and sulfate concentrations and is usually derived from urban water cycling and subordinately from agricultural practices. Mixed groundwaters between cold and hydrothermal components are predominantly found in the lower Atemajac Valley. Tritium method elucidated that practically all of the sampled groundwater contains at least a small fraction of modern water. The multivariate mixing model M3 indicates that the proportion of hydrothermal fluids in sampled well water is between 13 (local groundwater) and 87% (hydrothermal water), and the proportion of polluted water in wells ranges from 0 to 63%. This study may help local water authorities to identify and quantify groundwater contamination and act accordingly.
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Kortelainen, Nina M., e Juha A. Karhu. "Geochemical and isotopic evolution of high-pH groundwater in a carbonate-bearing glacigenic aquifer, SW Finland". Hydrology Research 40, n. 1 (1 febbraio 2009): 19–31. http://dx.doi.org/10.2166/nh.2009.032.
Testo completoAbstract (sommario):
The glacigenic Virttaankangas aquifer in SW Finland is characterized by groundwaters with high pH values of up to 9.5. High pH values exceeding 9 are uncommon for shallow groundwaters from unconsolidated glacigenic formations on crystalline bedrock. To evaluate the geochemical evolution of groundwater, water samples were collected from 17 sites. The samples were analysed for the isotopic composition of oxygen, hydrogen, dissolved inorganic carbon (DIC) and strontium, the activities of radiocarbon and tritium, and for the basic chemical composition. Groundwaters in the Virttaankangas aquifer system show a considerable range in water pH from 6.4 to 9.5. The isotopic and chemical characteristics of the groundwater in the aquifer units were observed to vary depending on the aquifer mineralogy, groundwater residence time and the openness of the system to CO2 exchange. The pH values were noted to increase in parallel with the contents of Ca and DIC and δ13CDIC. In higher pH values, the groundwaters had attained saturation with respect to calcite. These chemical changes were interpreted to result from dissolution of calcite, present in trace amounts in the Virttaankangas sediments. Specifically, the highest pH values were attributed to calcite dissolution under closed system conditions at a low partial pressure of CO2.
46
Nishimoto, Naoto, Yosuke Yamamoto, Saburo Yamagata, Toshifumi Igarashi e Shingo Tomiyama. "Acid Mine Drainage Sources and Impact on Groundwater at the Osarizawa Mine, Japan". Minerals 11, n. 9 (13 settembre 2021): 998. http://dx.doi.org/10.3390/min11090998.
Testo completoAbstract (sommario):
Understanding the origin of acid mine drainage (AMD) in a closed mine and groundwater flow system around the mine aids in developing strategies for environmental protection and management. AMD has been continuously collected and neutralized at Osarizawa Mine, Akita Prefecture, Japan, since the mine was closed in the 1970s, to protect surrounding river water and groundwater quality. Thus, water samples were taken at the mine and surrounding groundwaters and rivers to characterize the chemical properties and environmental isotopes (δ2H and δ18O). The results showed that the quality and stable isotope ratios of AMD differed from those of groundwater/river water, indicating that the recharge areas of AMD. The recharge area of AMD was evaluated as the mountain slope at an elevation of 400–500 m while that of the surrounding groundwater was evaluated at an elevation of 350–450 m, by considering the stable isotopes ratios. This indicates that the groundwater affected by AMD is limited to the vicinity of the mine and distributed around nearby rivers.
47
Chen, P. A., C. Y. Peng, S. H. Liu e H. Paul Wang. "Removal of toxic arsenic(iii) from an old endemic black-foot disease groundwater by oxidative electrosorption". Environmental Chemistry 20, n. 3 (20 giugno 2023): 137–43. http://dx.doi.org/10.1071/en23001.
Testo completoAbstract (sommario):
Environmental context Naturally occurring arsenic was the likely cause of endemic black foot disease in groundwaters in Taiwan, and levels still exceed Taiwan EPA water quality standards. A method for the clean-up of these groundwaters that is both feasible and environmentally friendly is urgently needed. Oxidation of As(III) as H3AsO3 to the less toxic As(V)− and removal of As in groundwater was performed quantitatively by electrosorption using materials derived from agricultural wastes; this shows that this method has the potential to be a novel, green remediation method. Rationale Naturally occurring arsenic in the groundwater caused black-foot disease (BFD) in the 1950s on the southwest seashore of Taiwan. Recently, we found that the concentration of arsenic in groundwater taken from currently sealed wells in areas previously affected by BFD remained higher than the Taiwan (EPA) water quality standard. Although clean tap water is available in that area, removal of arsenic from the groundwater is of great importance to expand possible utilisation. Methodology Removal of arsenic from two old endemic BFD groundwaters with activated carbon (AC) electrodes recycled from agricultural wastes by electrosorption using capacitive deionisation (CDI) processes was studied. A better understanding of arsenic electrochemistry involved in electrosorption was investigated by in situ X-ray absorption near-edge structure spectroscopy. Results Arsenic removal efficiencies (61–93%) remained high across concentrations (5 and 196 mg/L). A high oxidation rate constant (0.93 h−1) for As(III)0 to As(V)− was found, allowing the electrosorption of As(V)− onto the meso- and micro-pores of the AC CDI electrodes with rate constants of 0.021 and 0.0013 h−1, respectively. Removal of arsenic from contaminated groundwater for drinking water was achieved with six CDI reactors in series. Moreover, in the presence of other ions (such as Na+, Mg2+ and Ca2+), 60–73% of As(III)0 and As(V)− ions were removed from the groundwaters by electrosorption. Discussion We have developed an engineering-feasible method for converting As(III)0 to less toxic As(V)−, enabling its removal by electrosorption, which demonstrates the feasibility for green remediation of BFD waters as well as other arsenic-contaminated groundwaters.
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Nefzaoui, Farah, Mohamed Fethi Ben Hamouda, Paula Maria Carreira, José Manuel Marques e Hans G. M. Eggenkamp. "Evidence for Groundwater Salinity Origin Based on Hydrogeochemical and Isotopic (2H, 18O, 37Cl, 3H, 13C, 14C) Approaches: Sousse, Eastern Tunisia". Water 15, n. 6 (22 marzo 2023): 1242. http://dx.doi.org/10.3390/w15061242.
Testo completoAbstract (sommario):
The key processes responsible for the rise in groundwater salinization in the Mio–Pliocene aquifer system of Sousse (Tunisia, eastern coastline) were identified through a multidisciplinary approach based on the use of geochemical, stable (2H, 13C, 18O and 37Cl) and radioactive (3H and 14C) isotope methods. In the study region, the mineralization of groundwaters is related to water–rock interaction ascribed to the dissolution of minerals in evaporite rocks, as well as to saltwater intrusion. Both processes explain the development of groundwaters in which Cl and Na dominantly determine the groundwater quality deterioration state. The isotopic and geochemical signatures of the studied groundwaters are clearly explained by the (i) occurrence of saline basins (sebkhas adjacent to the study region), (ii) type of rocks found below the ground surface, and (iii) cation exchange between clays and groundwaters.
49
Dayani, D. A., W. Wilopo e I. Azwartika. "Groundwater Balance Estimation and Quality For Irrigation In The Food Estate Area, Central Sumba Regency, East Nusa Tenggara, Indonesia". IOP Conference Series: Earth and Environmental Science 1378, n. 1 (1 luglio 2024): 012021. http://dx.doi.org/10.1088/1755-1315/1378/1/012021.
Testo completoAbstract (sommario):
Abstract Food estate in Central Sumba Regency is one of Indonesia’s Nasional Strategic Projects that aim to increase the national food supply. Groundwater has been the main water supply by residents around the food estate area in Central Sumba Regency. Groundwater exploitation in the research area uses dug wells, bore wells, and springs. They mostly use groundwater for domestic use and irrigation purposes. Aquifer depletion and declining groundwater levels can occur as groundwater is exploited too much due to the growing need for groundwater. Hence, determining the groundwater budget is required to ensure the basin’s sustainability. This study aims to determine groundwater quality for irrigation in the food estate and estimate the groundwater budget. Besides, water quality is also an important feature of groundwater, and it expresses how sufficient the water is for various needs, each having its requirements represented as water quality standards. Groundwater samples were taken from various areas in the research area, and groundwater’s physical-chemical properties, such as TDS, EC, temperature, and pH, were measured in the field and compared with Government Regulation no. 22, 2021, and FAO for irrigation water quality standards. The results show that the research area has a low to medium groundwater potential. The result of physical-chemical properties measurement are as follows TDS value is 183 mg/L on average, EC value is 366 μS/cm on average, the temperature value is 25.4°C on average, and pH value is 7.3 on average. It can be concluded that all of the samples met the standards.
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Neal, C., A. J. Robson, P. Shand, W. M. Edmunds, A. J. Dixon, D. K. Buckley, S. Hill et al. "The occurrence of groundwater in the Lower Palaeozoic rocks of upland Central Wales". Hydrology and Earth System Sciences 1, n. 1 (31 marzo 1997): 3–18. http://dx.doi.org/10.5194/hess-1-3-1997.
Testo completoAbstract (sommario):
Abstract. A series of boreholes of up to 50 m depth, drilled into Lower Palaeozoic mudstone, shale and greywacke bedrock in the headwater catchment areas of the River Severn at Plynlimon in Central Wales, shows an extensive chemically- and hydrologically-active shallow groundwater fracture flow system. Groundwater chemistry varies in space and time with lowest water levels and highest alkalinities occurring during the drier summer months. The groundwaters are enriched in base cations, silica, sulphate and alkalinity relative to surface waters indicating significant silicate weathering sources and sulphide oxidation. These sources provide important contributions to both stream water quality and flow. At one site, the introduction of a borehole near to the main river opened bedrock fractures which increased the amount of groundwater entering the river. This had a profound effect on the river water quality by increasing the pH, alkalinity and calcium concentrations. As well as pointing to the possibility of the wider availability of groundwater resources in upland areas, the results highlight (a) the potential value of groundwater as a acid neutralizing resource, (b) the importance of weathering processes and flow routing within the groundwater environment for stream water chemistry, (c) the potential for altering stream water quality by manipulation of groundwater routing and (d) the need to include groundwater characteristics in hydrochemical management models of surface water acidification.