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Coking industry is a potential source of heavy metals (HMs) pollution. However, its impacts to the groundwater of surrounding residential areas have not been well understood. This study investigated the pollution characteristics and health risks of HMs in groundwater nearby a typical coking plant. Nine HMs including Fe, Zn, Mo, As, Cu, Ni, Cr, Pb and Cd were analyzed. The average concentration of total HMs was higher in the nearby area (244.27 µg/L) than that of remote area away the coking plant (89.15 µg/L). The spatial distribution of pollution indices including heavy metal pollution index (HPI), Nemerow index (NI) and contamination degree (CD), all demonstrated higher values at the nearby residential areas, suggesting coking activity could significantly impact the HMs distribution characteristics. Four sources of HMs were identified by Positive Matrix Factorization (PMF) model, which indicated coal washing and coking emission were the dominant sources, accounted for 40.4%, and 31.0%, respectively. Oral ingestion was found to be the dominant exposure pathway with higher exposure dose to children than adults. Hazard quotient (HQ) values were below 1.0, suggesting negligible non-carcinogenic health risks, while potential carcinogenic risks were from Pb and Ni with cancer risk (CR) values > 10-6. Monte Carlo simulation matched well with the calculated results with HMs concentrations to be the most sensitive parameters. This study provides insights into understanding how the industrial coking activities can impact the HMs pollution characteristics in groundwater, thus facilitating the implement of HMs regulation in coking industries.
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Coque , Monitoreo del Ambiente , Agua Subterránea , Metales Pesados , Contaminantes Químicos del Agua , Metales Pesados/análisis , Agua Subterránea/química , Agua Subterránea/análisis , Contaminantes Químicos del Agua/análisis , Medición de Riesgo , HumanosRESUMEN
Polybromodiphenyl ethers (PBDEs), the widely used flame retardants, are common contaminants in surface soils at e-waste recycling sites. The association of PBDEs with soil colloids has been observed, indicating the potential risk to groundwater due to colloid-facilitated transport. However, the extent to which soil colloids may enhance the spreading of PBDEs in groundwater is largely unknown. Herein, we report the co-transport of decabromodiphenyl ester (BDE-209) and soil colloids in saturated porous media. The colloids released from a soil sample collected at an e-waste recycling site in Tianjin, China, contain high concentration of PBDEs, with BDE-209 being the most abundant conger (320 ± 30 mg/kg). The colloids exhibit relatively high mobility in saturated sand columns, under conditions commonly observed in groundwater environments. Notably, under all the tested conditions (i.e., varying flow velocity, pH, ionic species and ionic strength), the mass of eluted BDE-209 correlates linearly with that of eluted soil colloids, even though the mobility of the colloids varies markedly depending on the specific hydrodynamic and solution chemistry conditions involved. Additionally, the mass of BDE-209 retained in the columns also correlates strongly with the mass of retained colloids. Apparently, the PBDEs remain bound to soil colloids during transport in porous media. Findings in this study indicate that soil colloids may significantly promote the transport of PBDEs in groundwater by serving as an effective carrier. This might be the reason why the highly insoluble and adsorptive PBDEs are found in groundwater at some PBDE-contaminated sites.
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Coloides , Retardadores de Llama , Agua Subterránea , Éteres Difenilos Halogenados , Contaminantes del Suelo , Suelo , Contaminantes Químicos del Agua , Éteres Difenilos Halogenados/análisis , Coloides/química , Agua Subterránea/química , Contaminantes del Suelo/análisis , Contaminantes del Suelo/química , Suelo/química , Contaminantes Químicos del Agua/análisis , China , Retardadores de Llama/análisis , Monitoreo del Ambiente , Modelos QuímicosRESUMEN
To understand the adaptation of water use strategy of plant community to habitat heterogeneity, we measured the δD and δ18O values of xylem water of shrubs and potential water sources (soil water in different layers or groundwater) of Ammopiptanthus mongolicus communities on sand dune and Gobi from April to September in 2021 in the Ulan Buh Desert. Employing the MixSIAR model, we examined the seasonal dynamics of water source of each shrub by quantifying the contribution of different potential water sources. The results showed that A. mongolicus and Artemisia xerophytica on sand dune mainly used soil water of 10-25 cm in April and May after heavy rain in early spring, whereas Artemisia ordosica mainly used soil water of 10-200 cm. During the drought event within summer from June to August, A. mongolicus increasingly used soil water of 100-200 cm and groundwater, but A. xerophytica and A. ordosica increased the usage of 50-200 cm soil water. After the moderate rain in September, A. mongolicus evenly used soil water in all layers and groundwater, whereas two Artemisia shrubs preferred soil water of 10-50 cm. On Gobi, A. mongolicus and Nitraria sphaerocarpa evenly used soil water in all layers in April and May, mainly used 50-150 cm soil water from June to August and used 10-50 cm soil water in September. Convolvulus tragacanthoides mainly used soil water of 10-50 cm (from April to May), 25-150 cm (from June to August), and 10-25 cm (in September), separately. There were seasonal differences in water use of three shrubs on sand dune and Gobi A. mongolicus communities. During drought, A. mongolicus on sand dune could use deep soil water and groundwater, and that on Gobi relied only on deep soil water, which was more sensitive to rainfall.
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Artemisia , Clima Desértico , Ecosistema , Suelo , Agua , China , Agua/análisis , Artemisia/crecimiento & desarrollo , Suelo/química , Estaciones del Año , Agua Subterránea/análisis , Agua Subterránea/química , Sequías , LluviaRESUMEN
Drained wetlands are thought to be carbon (C) source hotspots, and rewetting is advocated to restore C storage in drained wetlands for climate change mitigation. However, current assessments of wetland C balance mainly focus on vertical fluxes between the land and atmosphere, frequently neglecting lateral carbon fluxes and land-use effects. Here, we conduct a global synthesis of 893 annual net ecosystem C balance (NECB) measures that include net ecosystem exchange of CO2, along with C input via manure fertilization, and C removal through biomass harvest or hydrological exports of dissolved organic and inorganic carbon, across wetlands of different status and land uses. We find that elevating water table substantially reduces net ecosystem C losses, with the annual NECB decreasing from 2579 (95% interval: 1976 to 3214) kg C ha-1 year-1 in drained wetlands to -422 (-658 to -176) kg C ha-1 year-1 in natural wetlands, and to -934 (-1532 to -399) kg C ha-1 year-1 in rewetted wetlands globally. Climate, land-use history, and time since water table changes introduce variabilities, with drainage for (sub)tropical agriculture or forestry uses showing high annual C losses, while the net C losses from drained wetlands can continue to affect soil C pools for several decades. Rewetting all types of drained wetlands is needed, particularly for those formerly agriculture-used (sub)tropical wetlands where net ecosystem C losses can be largely reduced. Our findings suggest that elevating water table is an important initiative to reduce C losses in degraded wetlands, which could contribute to policy decisions for managing wetlands to enhance their C sequestration.
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Ciclo del Carbono , Cambio Climático , Humedales , Carbono/análisis , Carbono/metabolismo , Agua Subterránea/química , Agua Subterránea/análisis , Agricultura/métodos , Biomasa , Ecosistema , Secuestro de CarbonoRESUMEN
Groundwater harbours unique species adapted to perpetual darkness. Groundwater fauna plays a crucial role in global ecosystem services, but contamination poses a threat to this keystone ecosystem. Diclofenac is a common non-steroidal anti-inflammatory drug of particular concern, due to its presence in both surface and groundwater. We assess the environmental risk of diclofenac in European groundwaters using different scenarios, analyzing Measured Environmental Concentrations (MECs) of diclofenac and estimating the Predicted No Effect Concentration (PNECs) through two approaches: considering the sensitivity of the groundwater crustacean Proasellus lusitanicus (Isopoda: Asellidae), and using surface water species as proxies. Our results show that scenarios based on surrogate species predict that groundwater ecosystems are at risk due to diclofenac contamination. On the other hand, the MECs of diclofenac were consistently lower than the PNEC of P. lusitanicus, suggesting that the current MECs do not pose a significant threat to this groundwater-adapted species. However, risk scenarios differ considering the sensitivity of other groundwater species, emphasizing the importance of considering multiple species' sensitivities in risk assessment. Therefore, we recommend establishing an environmental quality standard for diclofenac in groundwater at 5 ng/L, a value that accounts the need for precautionary measures to safeguard groundwater ecosystems, essential for preserving their unique biota and services.
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Diclofenaco , Monitoreo del Ambiente , Agua Subterránea , Contaminantes Químicos del Agua , Diclofenaco/análisis , Agua Subterránea/química , Agua Subterránea/análisis , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/efectos adversos , Animales , Monitoreo del Ambiente/métodos , Europa (Continente) , Medición de Riesgo , Isópodos/efectos de los fármacos , Antiinflamatorios no Esteroideos/análisis , Antiinflamatorios no Esteroideos/efectos adversos , EcosistemaRESUMEN
Good quality water for human consumption, irrigation, and industrial use is very important. Today, around the world, water is contaminated by natural processes and human activities. This study aimed to evaluate the suitability of groundwater for drinking and irrigation, identify the source of fluoride and nitrate contamination, and assess the human health risks around the Cauvery River basin in southern India. A total of 30 groundwater samples were collected and analyzed for hydrochemical parameters, including EC, TDS, pH, Ca, Mg, Na, K, HCO3, Cl, SO4, NO3, and F-. The majority of groundwater samples in the study area are used for drinking and irrigation. The pH of groundwater in the study area was observed to be dominantly alkaline. The levels of TDS, Ca, Na, K, F, and TH exceeded the permissible limits recommended by BIS and WHO. Fluoride and nitrate levels in groundwater exceeded the permissible limits for drinking purposes in 43% and 50% of the samples, respectively. The excessive concentration of fluoride and nitrate in groundwater could pose serious human health problems. Fluoride and nitrate concentrations in groundwater vary between 0.1 and 2 mg/l and 12 and 95 mg/l, respectively. Based on the computation of the drinking water quality index, about 73% of groundwater samples were classified as excellent to good. Health risk was assessed for infants, children, and adults using non-carcinogenic risk indices such as hazard quotients (HQ), hazard indexes (HI), total hazard indices (THI), and carcinogenic risk indices (CR). Infants, children, and adults have different total hazards indexes ranging from 1.508 to 5.733, 1.579 to 6.003, and 0.011 to 0.046, respectively. Health risk assessment results indicated that the hazard index and hazard quotient were above the recommended limit of > 1 in most of the samples for infants and children. Non-carcinogenic risk and carcinogenic risks were more likely to affect infants and children rather than adults through ingestion of contaminated water.
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Monitoreo del Ambiente , Fluoruros , Agua Subterránea , Nitratos , Ríos , Contaminantes Químicos del Agua , Calidad del Agua , India , Humanos , Fluoruros/análisis , Nitratos/análisis , Contaminantes Químicos del Agua/análisis , Agua Subterránea/química , Medición de Riesgo , Ríos/química , Agua Potable/químicaRESUMEN
Groundwater depletion and water scarcity are pressing issues in water-limited regions worldwide, including Pakistan, where it ranks as the third-largest user of groundwater. Lahore, Pakistan, grapples with severe groundwater depletion due to factors like population growth and increased agricultural land use. This study aims to address the lack of comprehensive groundwater availability data in Lahore's semi-arid region by employing GIS techniques and remote sensing data. Various parameters, including Land Use and Land Cover (LULC), Rainfall, Drainage Density (DD), Water Depth, Soil Type, Slope, Population Density, Road Density, Normalized Difference Vegetation Index (NDVI), Normalized Difference Built-Up Index (NDBI), Moisture Stress Index (MSI), Water Vegetation Water Index (WVWI), and Land Surface Temperature (LST), are considered. Thematic layers of these parameters are assigned different weights based on previous literature, reclassified, and superimposed in weighted overlay tool to develop a groundwater potential zones index map for Lahore. The groundwater recharge potential zones are categorized into five classes: Extremely Bad, Bad, Mediocre, Good, and Extremely Good. The groundwater potential zone index (GWPZI) map of Lahore reveals that the majority falls within the Bad to Mediocre recharge potential zones, covering 33% and 28% of the total land area in Lahore, respectively. Additionally, 14% of the total area falls under the category of Extremely Bad recharge potential zones, while Good to Extremely Good areas cover 19% and 6%, respectively. By providing policymakers and water supply authorities with valuable insights, this study underscores the significance of GIS techniques in groundwater management. Implementing the findings can aid in addressing Lahore's groundwater challenges and formulating sustainable water management strategies for the city's future.
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Monitoreo del Ambiente , Sistemas de Información Geográfica , Agua Subterránea , Tecnología de Sensores Remotos , Pakistán , Agua Subterránea/química , Monitoreo del Ambiente/métodos , Abastecimiento de Agua/estadística & datos numéricos , Agricultura/métodosRESUMEN
This paper presents findings on groundwater physiochemical composition and radioactivity levels in households in Bac Lieu province, Vietnam. Through discriminant analysis, it was observed that groundwater quality exhibits spatial variations corresponding to saline intrusion zones. The paired-samples T-tests revealed significantly different ratios of Ra-224, Ra-226, and Ra-228 isotopes between Na-Cl and Ca-Na-HCO3 water types. All three water types had a ratio of Ra-226/Ra-228 of approximately one, indicating the presence of groundwater aquifers beneath the crust and fluvial marine sediment. Furthermore, strong associations between sulfate and calcium suggest that CO2 enrichment in groundwater aquifers indicates anoxic aquatic environments. Twenty-five of the thirty-three evaluated samples exceeded the national technical regulations for domestic water quality with parameters such as chloride, sulfate, sodium, gross alpha, or total dissolved solids. Fifteen samples exceeded gross alpha's allowable contamination threshold of 0.1 Bq/L. The combination of Ra-226 and Ra-228 did not surpass the U.S. Environmental Protection Agency's recommended limit of 0.185 Bq/L. However, nineteen samples exhibited annual committed effective doses of radium isotopes for infants that exceeded the WHO recommendation of 0.1 mSv/year.
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Agua Subterránea , Radio (Elemento) , Contaminantes Radiactivos del Agua , Vietnam , Agua Subterránea/química , Contaminantes Radiactivos del Agua/análisis , Humanos , Radio (Elemento)/análisis , Monitoreo de Radiación/métodos , Composición Familiar , Sulfatos/análisisRESUMEN
Groundwater serves a range of essential functions such as supplying drinking water, facilitating agricultural practices, and supporting industrial processes. This study examines with multiple methods the quality of groundwater in the agricultural region of Dzira, Algeria. By collecting 38 groundwater samples of different wells and boreholes, valuable awareness of the aptness of groundwater for irrigation in this arid landscape was gained. Most wells met Food and Agriculture Organization (FAO) criteria for the total dissolved solids (TDS) and the potential of hydrogen pH, but some areas had higher mineral content and electrical conductivity. Results show significant TDS variations, with 10.81% of wells exceeding limits and acceptable pH levels. Elevated EC values in 67.57% of wells show high salinity, affecting soil and plant growth. Major ions such as Mg2+ and SO4- exceeded FAO standards in 43.24% and 64.86% of wells, respectively, highlighting substantial mineral content in the groundwater. Suitability indices reveal that most wells pose low sodium hazards and are generally suitable for irrigation, though some areas face moderate to high restrictions. The irrigation water quality index (IWQI) ranged from 45.36 to 96.30, averaging 80.77, with 54.04% classified as "low restriction," suitable for sandy soils with good permeability but requiring caution on salt-sensitive soils. Hydrogeochemical analysis using principal component analysis (PCA) and hierarchical cluster analysis (HCA) identifies rapid evaporite dissolution from Triassic saline formations, with a correlation matrix showing associations between TDS and Ca2âº, Mg2âº, Naâº, Clâ», and SO42â». This mineralization is likely from gypsum and halite. Zoning maps based on IWQI and other parameters depicted spatial variations in groundwater quality, guiding effective irrigation management strategies. Overall, the study underscores the importance of comprehensive water quality assessment for sustainable agriculture and emphasizes the need for targeted interventions to mitigate potential challenges associated with soil salinity and sodicity. Therefore, these findings can be useful to decision-makers and stakeholders in order to optimize water use and protect this vital resource.
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Riego Agrícola , Monitoreo del Ambiente , Agua Subterránea , Calidad del Agua , Argelia , Agua Subterránea/química , Agricultura/métodos , Contaminantes Químicos del Agua/análisis , Suelo/químicaRESUMEN
Groundwater is one of the chief water sources for agricultural activities in an aggregation of coal mines surrounded by agricultural areas in the Huaibei Plain. However, there have been few reports on whether mining-affected groundwater can be adopted for agricultural irrigation. We attempted to address this question through collecting 71 shallow groundwater samples from 12 coal mining locations. The Piper trilinear chart, the Gibbs diagram, the proportional coefficient of major ions, and principal component analysis were examined to characterize the source, origin, and formation process of groundwater chemical composition. The suitability for agricultural irrigation was evaluated by a final zonation map that establishes a comprehensive weighting model based on analytic hierarchy process and criteria importance though the intercriteria correlation (AHP-CRITIC). The results revealed that the groundwater was classified as marginally alkaline water with a predominant cation of HCO3- and anion of Na+. Total hardness, total dissolved solids, sulfate (SO42-), sodium (Na+), and fluoride (F-) were the primary ions that exceeded the standard. The results also indicated that the dominant hydrochemical facies were Ca-HCO3 and Na-Cl. The dissolution of carbonate, silicate, sulfate minerals, along with cation exchange, were the main natural drivers controlling the hydrogeochemical process of groundwater. The zonation map suggested that 43.17%, 18.85%, and 37.98% of the study area were high, mediate, and low suitability zones, respectively. These results from this study can support policymakers for better managing groundwater associated with a concentration of underground coal mines.
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Minas de Carbón , Monitoreo del Ambiente , Agua Subterránea , Contaminantes Químicos del Agua , Agua Subterránea/química , China , Contaminantes Químicos del Agua/análisis , AgriculturaRESUMEN
One reason arid and semi-arid environments have been used to store waste is due to low groundwater recharge, presumably limiting the potential for meteoric water to mobilize and transport contaminants into groundwater. The U.S. Department of Energy Office of Legacy Management (LM) is evaluating selected uranium mill tailings disposal cell covers to be managed as evapotranspiration (ET) covers, where vegetation is used to naturally remove water from the cover profile via transpiration, further reducing deep percolation. An important parameter in monitoring the performance of ET covers is soil moisture (SM). If SM is too high, water may drain into tailings material, potentially transporting contaminants into groundwater; if SM is too low, radon flux may increase through the cover. However, monitoring SM via traditional instrumentation is invasive, expensive, and may fail to account for spatial heterogeneity, especially over vegetated disposal cells. Here we investigated the potential for non-invasive SM monitoring using radar remote sensing and other geospatial data to see if this approach could provide a practical, accurate, and spatially comprehensive tool to monitor SM. We used theoretical simulations to analyze the sensitivity of multi-frequency radar backscatter to SM at different depths of a field-scale (3 ha) drainage lysimeter embedded within an in-service LM disposal cell. We then evaluated a shallow and deep form of machine learning (ML) using Google Earth Engine to integrate multi-source observations and estimate the SM profile across six soil layers from depths of 0-2 m. The ML models were trained using in situ SM measurements from 2019 and validated using data from 2014 to 2018 and 2020-2021. Model predictors included backscatter observations from satellite synthetic aperture radar, vegetation, temperature products from optical infrared sensors, and accumulated, gridded rainfall data. The radar simulations confirmed that the lower frequencies (L- and P-band) and smaller incidence angles show better sensitivity to deeper soil layers and an overall larger SM dynamic range relative to the higher frequencies (C- and X-band). The ML models produced accurate SM estimates throughout the soil profile (r values from 0.75 to 0.94; RMSE = 0.003-0.017 cm3/cm3; bias = 0.00 cm3/cm3), with the simpler shallow-learning approach outperforming a selected deep-learning model. The ML models we developed provide an accurate, cost-effective tool for monitoring SM within ET covers that could be applied to other vegetated disposal cell covers, potentially including those with rock-armored covers.
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Aprendizaje Automático , Tecnología de Sensores Remotos , Suelo , Uranio , Uranio/análisis , Suelo/química , Agua Subterránea/química , Monitoreo del Ambiente/métodosRESUMEN
The residual air saturation plays a crucial role in modeling hydrological processes of groundwater and the migration and distribution of contaminants in subsurface environments. However, the influence of factors such as media properties, displacement history, and hydrodynamic conditions on the residual air saturation is not consistent across different displacement scenarios. We conducted consecutive drainage-imbibition cycles in sand-packed columns under hydraulic conditions resembling natural subsurface environments, to investigate the impact of wetting flow rate, initial fluid state, and number of imbibition rounds (NIR) on residual air saturation. The results indicate that residual air saturation changes throughout the imbibition process, with variations separated into three distinct stages, namely, unstable residual air saturation (Sgr-u), momentary residual air saturation (Sgr-m), and stable residual air saturation (Sgr). The results also suggest that the transition from Sgr-u to Sgr is driven by changes in hydraulic pressure and gradient; the calculated values followed the following trend: Sgr > Sgr-u > Sgr-m. An increase in capillary number, which ranged from 1.46 × 10-7 to 3.07 × 10-6, increased Sgr-u and Sgr-m in some columns. The increase in Sgr ranged from 0.034 to 0.117 across all the experimental columns; this consistent increase can be explained by water film expansion at the primary wetting front along with a strengthening of the hydraulic gradient during water injection. Both the pre-covered water film on the sand grain surface and a pore-to-throat aspect ratio of up to 4.42 were identified as important factors for the increased residual air saturation observed during the imbibition process. Initial air saturation (Sai) positively influenced all three types of residual air saturation, while initial capillary pressure (Pci) exhibited a more pronounced inhibitory effect on residual air saturation, as it can partly characterized the initial connectivity of the air phase generated under different drying flow rates. Under identical wetting flow rate conditions, Sgr was higher during the second imbibition than during the first imbibition due to variations in initial fluid state, involving both fluid distribution and the concentration of dissolved air in the pore water. In contrast, NIR did not have an obvious effect on the three types of residual air saturation. This work aims to provide empirical evidences and offer further insights into the capture of non-wetting phases in groundwater environments, as well as to put forward some potential suggestion for future investigations on the retention and migration of contaminants that involves multiphase interface interactions in subsurface environments.
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Aire , Agua Subterránea , Agua Subterránea/química , Arena , Hidrodinámica , Movimientos del AguaRESUMEN
In Bangladesh, groundwater, the principal source of drinking water, contains predominantly high levels of iron. Drinking groundwater is associated with good iron status in populations. Against this backdrop, iron supplementation is often associated with side effects, which reduces its intake compliance. However, the level of iron in groundwater is not consistent, and low levels exist in many areas of the country. In the present study, we examined the role of groundwater with a low concentration of iron in the prevention of anemia in Bangladeshi children. In 2018, a cross-sectional study was conducted in Bangladesh among children aged 2-5 years (n = 122) who drank groundwater containing a low level of iron (0-<2 mg/L). The combined intake of iron was calculated from the key sources-diet, groundwater, and the simulated intake of MNPs. The intakes of iron were compared against the standard reference intake. The children's hemoglobin levels were measured using a photometer. The combined intake of iron from diet, groundwater with low levels of iron, and the simulated consumption of low-iron MNP in children was 5.8 ± 2.0 and 6.9 ± 2.5 mg/day, comprising 193% and 169% of the Estimated Average Requirements in the 2-3-year-old and 4-5-year-old subgroups, respectively. The combined intake of bioavailable iron from dietary and low-iron groundwater was 0.42 ± 0.023 and 0.22 ± 0.019 mg/day in children exposed to groundwater concentrations of 0.8-<2.0 mg/L and 0.0-<0.8 mg/L, respectively (p < 0.001). The mean concentration of hemoglobin in the respective groups was 12.17 ± 0.94 g/dL and 11.91 ± 0.91 g/dL (p = 0.30). The combined intake of iron from diet and the low-iron groundwater was associated with maintenance of hemoglobin concentration at the non-anemic level in > 90% of the children. The findings highlight the protective influence of the low concentration of iron in the drinking groundwater against childhood anemia in Bangladesh.
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Agua Subterránea , Hierro , Población Rural , Humanos , Bangladesh/epidemiología , Agua Subterránea/química , Agua Subterránea/análisis , Estudios Transversales , Preescolar , Masculino , Femenino , Hierro/administración & dosificación , Hierro/sangre , Anemia Ferropénica/prevención & control , Anemia Ferropénica/epidemiología , Agua Potable/química , Agua Potable/análisis , Hemoglobinas/análisis , Suplementos Dietéticos , DietaRESUMEN
Chemical and isotopic indicators were used to recognize the origin of hydrothermal groundwater, to assess the mineralization processes and groundwater quality, to identify the source of solutes and the likely mixing with cold, and elucidate the fluid geothermometry in the Jérid field of Southern Tunisia. The results show that the geothermal groundwater is neutral to slightly alkaline. They are characterized by SO4-Cl-Na-Ca water type. The dissolution of evaporates and pyrite-bearing rocks is the dominant mineralization process. The groundwater quality index indicates that the majority of samples are very hard and belong to poor to unsuitable for drinking classes. Applications and calculations of hydrogeochemical parameters, including SAR, %Na, PI, Kr, and MAR, showed that the majority of samples are unsuitable for agricultural practices. The human health risk was assessed based on hazard quotient and total hazard index through ingestion and dermal contact with iron-rich groundwater. The consumption of CI groundwaters does not present non-carcinogenic risk to adults and children. The δ18 O and δ2H signatures indicate that the geothermal groundwater was recharged by ocean precipitation during cold and wet paleoclimatic periods. The slight enrichment of oxygen-18 and deuterium contents suggests a limited mixing effect between geothermal water and cold groundwater within the same aquifer. This mixing effect is confirmed by the Na-K-Mg and the chloride-enthalpy diagrams. The K-Mg and SiO2 geothermometers provided fairly reliable reservoir temperature values, ranging between 69.6 and 99 °C. Calculated geothermal potential values, varying between 469 and 16987 kWth, which allow several applications such as domestic and agricultural heating.
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Monitoreo del Ambiente , Agua Subterránea , Contaminantes Químicos del Agua , Túnez , Agua Subterránea/química , Monitoreo del Ambiente/métodos , Contaminantes Químicos del Agua/análisis , Isótopos de Oxígeno/análisisRESUMEN
To better understand the impact of long-term irrigation practices on arsenic (As) accumulation in agricultural soils, 100 soil samples from depths of 0-20â¯cm were collected from the Datong basin, where the As-contaminated groundwater has been used for irrigation for several decades. Soil samples were analyzed for major elements, trace elements, and As, Fe speciation. Results reveal As content ranging from 4.00 to 14.5â¯mg/kg, an average of 10.2 ± 2.05â¯mg/kg, consistent with surveys conducted in 1998 and 2007. Arsenic speciation ranked in descending order as follows: As associated with silicate minerals (AsSi, 29.70 ± 7.53â¯%) > amorphous Fe-minerals associated As (AsFeox1, 26.40 ± 3.27â¯%) > crystalline Fe-minerals associated As (AsFeox2, 24.02 ± 4.60â¯%) > strongly adsorbed As (AsSorb, 14.29 ± 2.81â¯%) > As combined with carbonates and Fe-carbonates (AsCar, 2.30 ± 0.44â¯%) > weakly adsorbed As (AsDiss, 2.59 ± 1.00â¯%). The anomalous negative correlation between As and Fe content reflects the primary influence of soil provenance. Evidence from major element compositions and rare earth element patterns indicates that total As and Fe contents in soils are controlled by parent materials, exhibiting distinct north-south differences (As: higher levels in the north, lower levels in the south; Fe: higher levels in the south, lower levels in the north). Evidence from the Chemical Index of Alteration (CIA) and As/Ti ratio suggests that chemical weathering has led to As enrichment in the central basin. Notably, relationships such as AsDiss/Ti, AsSorb/Ti with CIA and total Fe content indicate significant influences of irrigation practices on adsorbed As (both weakly and strongly adsorbed) contents, showing a pattern of higher levels in the central basin and lower levels in the Piedmont. However, total As content remained stable after long-term irrigation, potentially due to the re-release of accumulated As via geochemical pathways during non-irrigated periods. These findings demonstrate that the soil systems can naturally remediate exogenous As contamination induced by irrigation practices. Quantitative assessment of the balance between As enrichment and re-release in soil systems is crucial for preventing soil As contamination, highlighting strategies like water-saving techniques and fallow periods to manage As contamination in agricultural areas using As-contaminated groundwater for irrigation.
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Riego Agrícola , Arsénico , Monitoreo del Ambiente , Agua Subterránea , Contaminantes del Suelo , Suelo , Riego Agrícola/métodos , Arsénico/análisis , Contaminantes del Suelo/análisis , Suelo/química , Agua Subterránea/química , Hierro/análisis , Hierro/química , Agricultura/métodos , Adsorción , Minerales/análisis , Minerales/químicaRESUMEN
Dimba Cave is a large array of natural galleries in limestone mountains of the Democratic Republic of the Congo that contains highly valued pre-historic archaeological artifacts. The cave attracts a high number of tourists every year and is used by local populations as a water supply source. The main objective of the research undertaken in Dimba Cave consisted of assessing the quality of water and sediments from Dimba Cave ponds through evaluating contamination by heavy metals (15 elements analyzed, including As, Cd, Pb, and Hg) and by microbial populations (including Escherichia coli and total coliforms) in order to estimate the ecotoxicological risk to humans and to non-human biota. All water samples collected in the cave ponds showed very high metal concentrations exceeding the internationally recommended limits for drinking water, particularly for Cr, Mn, As, Pb, and Hg. Most sediment samples from cave ponds also displayed high heavy metal concentrations. The calculated pollution parameters, such as the enrichment factor (EF), and ecological risk parameters, such as the ecological risk index (Eri), indicated that the sediment may be toxic to aquatic biota. Furthermore, the microbiological analysis of pond waters indicated a widespread contamination with bacteria such as Escherichia coli, Enterococcus spp., total coliforms, and Pseudomonas spp., probably from anthropogenic and/or animal sources. Therefore, the consumption of Dimba Cave water as a drinking water represents a threat to public health. Urgent management measures should be enforced to protect public health and the cave ecosystem.
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Cuevas , Monitoreo del Ambiente , Sedimentos Geológicos , Agua Subterránea , Metales Pesados , Contaminantes Químicos del Agua , República Democrática del Congo , Medición de Riesgo , Metales Pesados/análisis , Metales Pesados/toxicidad , Sedimentos Geológicos/química , Sedimentos Geológicos/microbiología , Sedimentos Geológicos/análisis , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/toxicidad , Agua Subterránea/química , Agua Subterránea/microbiología , Microbiología del Agua , Escherichia coli/efectos de los fármacos , Escherichia coli/aislamiento & purificación , HumanosRESUMEN
Colloidal activated carbon (CAC) is an emerging remedial enhancement fluid that is injected into the subsurface to adsorb hazardous industrial compounds for subsequent removal. CAC-enhanced remediation relies on accurate subsurface characterization and monitoring to ensure CAC reaches intended treatment locations. The objective of this study was to assess the effectiveness of the spectral induced polarization (SIP) technique to track CAC migration within porous media and its adsorption of the chlorinated solvent, tetrachloroethylene (PCE). Dynamic column experiments were performed with cyclic injection and flow of groundwater, CAC, and PCE within porous media, and simultaneous measurements of SIP and effluent quality. Results showed an increase in both the real and imaginary conductivities of the SIP response during injection/flow of CAC within porous media. Real conductivity returned to pre-CAC levels during subsequent flushing of CAC with groundwater, which had left behind only carbon-coated soil grains; however, imaginary conductivity identified the change in polarizability due to the alterations on the grain surface. The subsequent adsorption of aqueous phase PCE did not generate a distinctive change in SIP response, mainly due to the low 50 mg/L concentrations used. Overall, this study suggests that SIP can be a valuable tool to effectively and non-invasively track the migration of injected CAC within porous media for contaminant adsorption, suggesting it can be used to enhance the implementation and management of environmental remediation programs.
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Carbono , Restauración y Remediación Ambiental , Agua Subterránea , Contaminantes Químicos del Agua , Agua Subterránea/química , Restauración y Remediación Ambiental/métodos , Contaminantes Químicos del Agua/química , Carbono/química , Adsorción , Tetracloroetileno/química , Carbón Orgánico/químicaRESUMEN
Construction and demolition wastes (CDWs) have become a significant environmental concern due to urbanization. CDWs in landfill sites can generate high-pH leachate and various constituents (e.g., acetate and sulfate) following the dissolution of cement material, which may affect subsurface biogeochemical properties. However, the impact of CDW leachate on microbial reactions and community compositions in subsurface environments remains unclear. Therefore, we created columns composed of layers of concrete debris containing-soil (CDS) and underlying CDW-free soil, and fed them artificial groundwater with or without acetate and/or sulfate. In all columns, the initial pH 5.6 of the underlying soil layer rapidly increased to 10.8 (without acetate and sulfate), 10.1 (with sulfate), 10.1 (with acetate), and 8.3 (with acetate and sulfate) within 35 days. Alkaliphilic or alkaline-resistant microbes including Hydrogenophaga, Silanimonas, Algoriphagus, and/or Dethiobacter were dominant throughout the incubation in all columns, and their relative abundance was highest in the column without acetate and sulfate (50.7-86.6%). Fe(III) and sulfate reduction did not occur in the underlying soil layer without acetate. However, in the column with acetate alone, pH was decreased to 9.9 after day 85 and Fe(II) was produced with an increase in the relative abundance of Fe(III)-reducing bacteria up to 9.1%, followed by an increase in the methanogenic archaea Methanosarcina, suggestive of methanogenesis. In the column with both acetate and sulfate, Fe(III) and sulfate reduction occurred along with an increase in both Fe(III)- and sulfate-reducing bacteria (19.1 and 17.7%, respectively), while Methanosarcina appeared later. The results demonstrate that microbial Fe(III)- and sulfate-reduction and acetoclastic methanogenesis can occur even in soils with highly alkaline pH resulting from the dissolution of concrete debris.
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Microbiología del Suelo , Suelo , Concentración de Iones de Hidrógeno , Suelo/química , Instalaciones de Eliminación de Residuos , Sulfatos/metabolismo , Anaerobiosis , Bacterias/metabolismo , Agua Subterránea/química , Agua Subterránea/microbiologíaRESUMEN
Zero-valent iron (ZVI) applied to the remediation of contaminated groundwater (GW) in situ, especially using engineered permeable reactive barriers (PRBs), has been proven to be an effective reactive material. However, many of ZVI brands do not represent tailored reagents specifically regarding destroying pollutants in GW. Thus, their reactivity towards certain contaminants in GW may vary significantly in a wide range even with different production batches of the same ZVI brand. This issue has rarely been known and consequently not addressed to a higher extend so far. Therefore, this study implemented extensive, long-term column experiments followed by short-term batch experiments for chlorinated volatile organic compounds (cVOCs) degradation for developing a semi-empirical test methodology to thoroughly resolve this pivotal issue by achieving an improved quality assurance guidance regarding proper field-scale emplacement of different ZVI brands and their production batches. The results showed that during column experiments perchloroethylene (PCE) led to a significant degradation up to a certain period but sulfate-reducing microorganisms enhanced the dehalogenation and led approximately to 100 % PCE removal. However, the efficacy varied for different ZVI brands, i.e., Gotthart Maier (GM) and Sponge Iron (Responge®). Furthermore, it could be shown that it might even vary among different production batches of the same ZVI brand. It was also observed that evolution of sulfate-reducing microorganisms may improve the efficacy of PCE degradation vastly that occur at different intensities with different ZVI brands and their respective production batches over time. Further, comparing comprehensive long-term column (kobs = 0.0488 1/h) and short-term batch experiments (kobs = 0.07794 1/h) as well as refined kinetic analyses (kobs = 0.0424 1/h) clearly prove that an appropriate guidance protocol for successful full-scale in situ remediation is required for properly select the right ZVI brand and production batch before it is loaded to a PRB in the field.
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Restauración y Remediación Ambiental , Agua Subterránea , Hierro , Contaminantes Químicos del Agua , Agua Subterránea/química , Hierro/química , Restauración y Remediación Ambiental/métodos , Compuestos Orgánicos VolátilesRESUMEN
The sulfur powder as electron donor in driving dual-chamber microbial fuel cell denitrification (S) process has the advantages in economy and pollution-free to treat nitrate-contained groundwater. However, the low efficiency of electron utilization in sulfur oxidation (ACE) is the bottleneck to this method. In this study, the addition of calcined pyrite to the S system (SCP) accelerated electron generation and intra/extracellular transfer efficiency, thereby improving ACE and denitrification performance. The highest nitrate removal rate reached to 3.55 ± 0.01 mg N/L/h in SCP system, and the ACE was 103 % higher than that in S system. More importantly, calcined pyrite enhanced the enrichment of functional bacteria (Burkholderiales, Thiomonas and Sulfurovum) and functional genes which related to sulfur metabolism and electron transfer. This study was more effective in removing nitrate from groundwater without compromising the water quality.