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1.
J Environ Qual ; 49(3): 723-734, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-33016394

RESUMO

Groundwater withdrawal has increased over the past several decades throughout the U.S. Upper Midwest, yet impacts of pumping on groundwater-dependent wetlands remain understudied. Here, we compared measures of floristic quality, hydrologic conditions, and nutrient availability in pairs of more-impacted fens and less-impacted fens throughout Wisconsin. Floristic quality was significantly lower in more-impacted fens than in less-impacted fens, the result of the disappearance of rare and specialist species and the increase in richness and cover of non-native and weedy species. Plots within more-impacted fens generally had lower root-zone volumetric water content, greater depth to water table, and higher available nitrogen and phosphorus than within less-impacted fens, although nonuniformly among or within sites. Lower volumetric water content predicted plot-level declines in floristic quality, richness of rare or specialist species, an increase in the number of non-native or problematic species, and an increase in cover of non-native and problematic species. Our results strongly suggest that groundwater withdrawals have substantial negative impacts on nearby fen quality and furthering imperilment of several species they contain.


Assuntos
Água Subterrânea , Hidrologia , Nitrogênio , Áreas Alagadas , Wisconsin
2.
J Environ Qual ; 49(3): 654-662, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-33016401

RESUMO

Continuous-flow iron and bio-iron columns were used to evaluate the effects of seepage velocity and concentration on Cr(VI) removal from groundwater. Solid-phase analysis showed that microorganisms accelerated iron corrosion by excreting extracellular polymeric substances and generated highly reactive minerals containing Fe(II), which gave the bio-iron column a longer life span and enhanced capacity for Cr(VI) removal via enhanced adsorption and reduction by reactive minerals. The bio-iron column showed much higher Cr(VI) removal capacity than the iron column with increasing Cr(VI) loading, which was obtained by increasing the seepage velocity or influent Cr(VI) concentration from 95 to 1138 m yr-1 and from 5 to 40 mg L-1 , respectively. When the Cr(VI) loading varied in a range of 0 to 10 mg L-1 h-1 , the bio-iron column had a 60% longer longevity and one- to sixfold higher Cr(VI) elimination capacity than the iron column. This result indicated that, under fluctuating hydraulic conditions [e.g., seepage velocity and Cr(VI) concentration], the presence of microorganisms can significantly boost Cr(VI) removal using Fe0 -based permeable reactive barriers.


Assuntos
Água Subterrânea , Poluentes Químicos da Água/análise , Adsorção , Cromo , Ferro
3.
J Environ Qual ; 49(2): 392-403, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33016417

RESUMO

Numerous studies have documented the linkages between agricultural nitrogen loads and surface water degradation. In contrast, potential water quality improvements due to agricultural best management practices are difficult to detect because of the confounding effect of background nitrate removal rates, as well as the groundwater-driven delay between land surface action and stream response. To characterize background controls on nitrate removal in two agricultural catchments, we calibrated groundwater travel time distributions with subsurface environmental tracer data to quantify the lag time between historic agricultural inputs and measured baseflow nitrate. We then estimated spatially distributed loading to the water table from nitrate measurements at monitoring wells, using machine learning techniques to extrapolate the loading to unmonitored portions of the catchment to subsequently estimate catchment removal controls. Multiple models agree that in-stream processes remove as much as 75% of incoming loads for one subcatchment while removing <20% of incoming loads for the other. The use of a spatially variable loading field did not result in meaningfully different optimized parameter estimates or model performance when compared with spatially constant loading derived directly from a county-scale agricultural nitrogen budget. Although previous studies using individual well measurements have shown that subsurface denitrification due to contact with a reducing argillaceous confining unit plays an important role in nitrate removal, the catchment-scale contribution of this process is difficult to quantify given the available data. Nonetheless, the study provides a baseline characterization of nitrate transport timescales and removal mechanisms that will support future efforts to detect water quality benefits from ongoing best management practice implementation.


Assuntos
Monitoramento Ambiental , Água Subterrânea , Agricultura , Nitratos/análise , Rios
4.
J Environ Qual ; 49(4): 909-920, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33016492

RESUMO

Regional groundwater phosphorus (P) concentrations are rarely reported, and it is important to develop a better understanding of background concentrations in shallow groundwater to help develop strategies to mitigate environmental risks. In this study, results collected from 17 different Iowa-based studies conducted from 2006 to 2019 and a total of 210 discrete locations of water table dissolved phosphate (DPO4 3- ) measurements are summarized (a) to assess the occurrence, range, and statistical distribution of groundwater DPO4 3- concentrations in Iowa and (b) to evaluate statewide patterns of DPO4 3- concentrations related to land use or land cover and landscape position. The DPO4 3- concentrations ranged from 0.02 to 1.56 mg L-1 and averaged 0.15 ± 0.19 mg L-1 with a median value of 0.10 mg L-1 (95% confidence interval of 0.08-0.11 mg L-1 ). Although minor variations were observed among land cover class and landscape position, concentrations exhibited uniformity across the state, likely attesting to the legacy of P from historical agricultural management. Median concentrations are higher than typical water quality criteria used to assess risk to surface water systems, implying that simply discharging groundwater DPO4 3- to streams, rivers, and lakes would be sufficient to cause environmental degradation.


Assuntos
Água Subterrânea , Fosfatos , Monitoramento Ambiental , Iowa , Qualidade da Água
5.
Environ Monit Assess ; 192(11): 684, 2020 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-33026519

RESUMO

Groundwater quality monitoring is a critical part of water management in all groundwater basins. In order to be effective and to meet the required needs, groundwater quality monitoring networks (GQMNs) must be designed to be able to operate long-term and economically without minimal disruption. The analytical hierarchical process (AHP), a multi-criteria decision-making program, was used to design a GQMN for an alluvial aquifer located in the Islam Abad plain west of Kermanshah province, Iran. This semi-arid area is subject to groundwater depletion and water quality changes. The model used 8 primary criteria sub-divided with 5 sub-criteria based on a combination of empirical data and expert opinion. The primary criteria included density of wells, well discharge, well depth, water quality (conductivity), flow direction, annual groundwater extraction, water level declines, and accessibility. The model showed that 59 of 254 production wells in the basin could provide optimal monitoring locations. When a second screening of the wells was used to determine constraints (physical conditions of the wells and pumps, owner permission of use, type of the pump, etc.), the number of wells was reduced to 13 wells. An initial round of water sampling and chemical analysis demonstrated that the design of the GQMN met the goals of the water management agency of the region.


Assuntos
Sistemas de Informação Geográfica , Água Subterrânea , Monitoramento Ambiental , Irã (Geográfico) , Poços de Água
6.
Environ Monit Assess ; 192(11): 683, 2020 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-33026556

RESUMO

The main objective of this research was to investigate the impact of the construction of Karkheh Dam in 2001 (referred to as the intervention time), on groundwater quality. The time series of total dissolved solids (TDS) and other water quality data including potassium (K+), sodium (Na+), magnesium (Mg2+), calcium (Ca2+), bicarbonate (HCO3-), sulfate (SO42-), and chloride (Cl-) for the period between 1996 and 2012 were analyzed. The magnitude of the trend by Sen's slope estimator for HCO3-, SO42-, and TDS was 0.005, - 0.02 and - 3.04, where a decline expected for SO42- and TDS, whereas for HCO3-, an increase was expected. According to the Pettitt's test, the mean of TDS decreased from 2306.9 mg/l between 1996 and 2002 to 797.2 mg/l between 2002 and 2012. During this time, the standard deviation of TDS declined from 2187.1 to 132.0 mg/l. The results of change point detection by the Pruned Exact Linear Time (PELT) algorithm were consistent with that of Pettitt's test providing confirmation that a change point in Ca2+, Mg2+, SO42-, and TDS time series data occurred in 2002.The findings from intervention analysis using the Bayesian structural time series (BSTS) technique showed that TDS concentration during the post-intervention period had an average value of 1127 mg/l compared with 1972 mg/l, before the dam construction. The time series of TDS demonstrated a decrease of about 43% following the intervention time.


Assuntos
Água Subterrânea , Poluentes Químicos da Água , Teorema de Bayes , Monitoramento Ambiental , Irã (Geográfico) , Poluentes Químicos da Água/análise
7.
Water Sci Technol ; 82(5): 998-1008, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031076

RESUMO

The feasibility of an advanced oxidation process based upon sodium persulfate (SPS) activated simultaneously by heat (50 °C) and nanoscale zero-valent iron (nZVI) on benzene removal was investigated. The experimental results strongly showed the synergistic effect of thermal and nZVI activation to SPS and benzene removal was enhanced with the increase of SPS/nZVI/benzene molar ratio. Specifically, 94% of benzene could be removed in 1 hr at 50 °C at the SPS/nZVI/benzene molar ratio of 10/5/1. The radical scavenger tests and electron paramagnetic resonance (EPR) analysis confirmed that SO4•- was the predominant species contributing to benzene degradation. Further, the effects of the solution matrix on benzene elimination were investigated. The results indicated that benzene destruction in the thermally activated SPS/nZVI system performed better under acidic conditions, and the high concentration of both Cl- and HCO3- had adverse effects on benzene elimination. The test for the performance of benzene degradation in the actual groundwater demonstrated that benzene could be degraded entirely at SPS/nZVI/benzene molar ratio of 40/40/1 at 50 °C, indicating that the synergistic catalysis of thermal and nZVI activation to SPS is exploitable and the thermally activated SPS/nZVI system can be applicable to the remediation of benzene contaminated groundwater.


Assuntos
Água Subterrânea , Poluentes Químicos da Água , Benzeno , Ferro , Oxirredução , Poluentes Químicos da Água/análise
8.
J Environ Manage ; 263: 110415, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32883481

RESUMO

Drinking water containing excess fluoride is a major health concern across the globe. The present study reports the feasibility of zirconium impregnated hybrid anion exchange resin (HAIX-Zr) for treating fluoride contaminated groundwater. The HAIX-Zr resin was prepared by impregnating ZrO2 nanoparticles on polymeric anion exchanger resin. Fluoride uptake by HAIX-Zr was quite rapid, 60% removal was obtained within 30 min. Kinetics of fluoride uptake by HAIX-Zr resin followed the pseudo-second-order kinetic model and adsorption data fitted best to Freundlich adsorption isotherm model. Maximum fluoride uptake capacity was observed as 12.0 mg/g. The defluoridation capacity of the resin decreases with increase in solution pH. The co-existing anions like chloride, phosphate, bicarbonate, nitrate, and sulphate at 100 mg/L concentration significantly affected fluoride removal and bicarbonate showed the highest interference. Continuous flow packed bed experiments were performed with real groundwater. To maintain a lower pH, weak acid cation exchange resin (INDION-236) was used before HAIX-Zr. It was observed that reducing the pH of the sample water to 4-4.5, increased the number of treated bed volumes fifteen times. Regeneration of fluoride-containing resin was done by passing 3% NaOH and 3% NaCl solution through an exhausted resin bed. The results revealed that HAIX-Zr can effectively remove fluoride from groundwater.


Assuntos
Água Subterrânea , Poluentes Químicos da Água/análise , Purificação da Água , Adsorção , Resinas de Troca de Ânions , Fluoretos , Concentração de Íons de Hidrogênio , Cinética , Zircônio
9.
Environ Monit Assess ; 192(10): 619, 2020 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-32885322

RESUMO

The present state of iron (Fe) and manganese (Mn) concentration in groundwater of Changchun city located within the Songnen Plain of northeastern China was evaluated in this study. Heavy metal sources, as well as triggering mechanism, were analyzed using a physicochemical, statistical and spatial approach. Results revealed that out of the 2600 samples analyzed, 214 (representing 8.24%) for Fe and 606 wells (representing 23.34%) for Mn exceeded the water standard. Organic matter-rich sediments and Fe-Mn nodules in aquifer and soil serve as sources of Fe and Mn. Organic and inorganic complex formations, as well as long residence time, were found to foster the release of Fe and Mn into groundwater. Additionally, pH and well depth was important in triggering Mn dissolution while groundwater mineralization, depth to the water table and well proximity to the river were found to have minimal/negligible effect on heavy metal mobilization. The removal of Fe and Mn from the water before use was proposed along with the sinking of deeper wells for groundwater exploitation to limit the use of polluted water.


Assuntos
Água Subterrânea , Poluentes Químicos da Água/análise , China , Monitoramento Ambiental , Ferro/análise , Manganês/análise
10.
Sci Total Environ ; 741: 140460, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32886997

RESUMO

Too little and too much fluorine are potentially hazardous for human health. In the Jiaokou Irrigation District, ionic concentrations, hydrogeochemistry, and fluoride contaminations were analyzed using correlation matrices, principal component analysis (PCA), and health risk assessment. The patterns for the average cation and anion concentrations were Na+ > Mg2+ > Ca2+ > K+ and SO42- > HCO3- > Cl- > NO3- > CO32-. The fluoride concentrations ranged between 0.29 and 8.92 mg/L (mean = 2.4 mg/L). 5% of the samples displayed lower than the recommended limit of 0.5 mg/L fluoride content, while 69% exceeded the allowable limits of 1.5 mg/L for drinking. The low F- content is distributed in a small part of the southeast, while elevated F- mainly in the central area of the study region. The PCA results indicated three principal components (PC), PC1 having the greatest variance (45.83%) and affected by positive loadings of TDS, Cl-, SO42-, Na+, and Mg2+, PC2 accounting for 17.03% and dominated by Ca2+, pH, HCO3-, and K+, and PC3 representing 12.17% and mainly comprising of CO32-. High fluoride groundwater is of the SO4-Cl-Na type, followed by HCO3-Na type. Evaporation and ion exchange play important roles in producing high fluoride groundwater. Furthermore, saturation index and anthropogenic activities also promote the high fluoride concentrations. The values of the total hazard quotient of 93% groundwater samples were greater than 1 for infants, followed by 85% for children, 68% for teenagers, and 57% for adults. Non-carcinogenic health risks to infants may occur over the entire study area, while for adults, health risks are mainly found in Weinan and Pucheng. High fluorine may have a potential negative influence on neurodevelopment, especially for infants and children. Adults in this region have serious dental fluorosis and skeletal fluorosis because of long-term drinking of high fluoride groundwater. Therefore, measures, including using organic fertilizers, strengthening defluoridation process, and optimizing water supply strategies, are necessary in this area.


Assuntos
Água Subterrânea , Poluentes Químicos da Água/análise , Adolescente , Adulto , Criança , China , Monitoramento Ambiental , Fluoretos/análise , Humanos , Medição de Risco
11.
Environ Monit Assess ; 192(10): 620, 2020 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-32888049

RESUMO

Groundwater in Delhi Metropolitan Region (DMR) is suffering from multiple catastrophes, viz., asymptotic increases in groundwater withdrawal, reduced recharge due to erratic rainfall, and variable soil type. In this study, we examined long-term trends in groundwater levels across the DMR from 1996 to 2018. Station level data collected by the Central Groundwater Board for 258 stations at the seasonal scale were visualized and interpreted using geospatial analysis. The spatial patterns of the trends in groundwater levels revealed increasing depths of groundwater levels, except the Yamuna River floodplains. The main cause for the decline is related to the rapid growth in population accompanied with high-density impervious urban land uses, leading to lower levels of recharge vs unlimited withdrawal of groundwater for daily needs. In addition, the local geology in the form of clayey soils in northwest DMR also contributed to the lower levels of recharge. The results of the analysis enabled us to establish the trend and delineate the zones of differential recharge. Furthermore, the level of contaminants were analyzed at the district level for fluorides and nitrates. The presence of fluoride contamination was mostly concentrated in the northwestern district, while the nitrate exceedance was more widespread. These findings will help in achieving the 6th Sustainable Development Goal (SDG) of United Nations by 2030 as well as goals identified in Delhi's master plan of 2041.


Assuntos
Monitoramento Ambiental , Água Subterrânea , Índia , Nitratos/análise , Rios
12.
Environ Monit Assess ; 192(10): 641, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32929589

RESUMO

Monitoring the groundwater quality situation and identifying the various pollution loads' sources are a prerequisites to finding solutions. In many areas, nitrate and salinity are one of the prime pollutants in the groundwater. This investigation is carried to present the results of a monitoring study focusing on 20 wells samples collected from the shallow groundwater of Guenniche plain (North Tunisia) during the wet season of May 2016, to present its suitability for drinking purposes with emphasis on the assessment of the presence of nitrate and salinity elements. Nitrate levels' results show that 55% of the samples exceeded the National Tunisian standard limit (NT) and the World Health Organization standard limit (WHO). The salinity results, measured as total dissolved solids (TDS), show that 95% of the samples exceed the international standard, and 25% exceed the national standard. A total of 20% of the wells exceeded the nitrite standards. The total hardness levels indicate that 90% of the samples present very hard water. The Guenniche shallow groundwater average concentrations are categorized as follows: Na+ > Ca2+ > Mg2+ > K+ for the cations and Cl- > SO42- > HCO3- > NO3- for the anions. Nitrate and salinity variations during the period 2006-2015 follow the rainfall fluctuation patterns. The assessment of water quality using Water Quality Index revealed that 95% of the wells' water classes ranged between "poor", "very poor," and "unsuitable for drinking purposes". Therefore, these wells are affected by anthropogenic and/or natural factors and they are inadvisable for drinking purposes, unless the water from these wells undergoes appropriate treatment before use.


Assuntos
Água Potável , Água Subterrânea , Poluentes Químicos da Água/análise , Monitoramento Ambiental , Salinidade , Tunísia , Qualidade da Água
13.
Ambio ; 49(11): 1808-1819, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32918720

RESUMO

In this study, we explored how a targeted land use change in a Danish catchment (River Odense) may provide multi-functional benefits through nitrogen (N)-load reductions to obtain good ecological quality in Odense estuary, protection of N-vulnerable groundwater aquifers, protection of Natura2000 sites and carbon sequestration. An N-load model linked to GIS thematic layers of known protected areas (Natura2000 sites and N-vulnerable groundwater aquifers) was utilised targeting high N-load areas to locate set-aside land. The achieved multi-functional benefits within the catchment and estuary were assessed and cost-benefit assessment was performed by dividing the total welfare costs of the set-aside by the total multi-functional benefits gained from each strategy. The results show that obtaining multi-functional benefits at the lowest cost requires a targeted shift of set-aside from the traditional hot-spot N-load areas to designated protected areas.


Assuntos
Água Subterrânea , Poluentes Químicos da Água/análise , Agricultura , Dinamarca , Monitoramento Ambiental , Nitrogênio/análise , Rios
14.
Environ Monit Assess ; 192(9): 577, 2020 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-32778965

RESUMO

Reports of environmental problems occasioned from gold mining activities had prompted the groundwater vulnerability prediction/assessment of the study area. This was with a view to identifying factors responsible for the probability of groundwater contamination as well as developing empirical (LR) model and map that predict the probability of occurrence of contaminant(s) with respect to threshold level in the groundwater resources in the study area. In order to achieve the objectives of the study, logistic regression was applied to independent variables obtained from results of the analysis of remote sensing and geophysical data on one hand and dependent variables obtained from analysis of water samples on the other hand. The results of the analysis obtained from water chemistry established that all the physio-chemical parameters and major metallic ions are within the permissible limit. However, zinc concentration (Zn), being the only dependent variable that had two categorical outcomes, was the contaminant utilized for the study. Similarly, only five (5) independent (predictive) variables, which are percent clay in soil, drainage, slope, unsaturated zone thickness, and total longitudinal conductance, were established to have good correlation and statistically significant with the dependent variable, the contaminant, and thus utilized in logistic regression model development. The quantitative assessment of the developed model established that the overall model prediction accuracy was 85.7% suggesting that the model had a very good fit. The probability prediction model was also accurate and reliable with percentage reliability established to be 90%. In conclusion, it is evident from the results obtained from the study that since the model developed was assessed to be accurate and reliable, the model, and hence the technique, can be replicated in another area of similar geologic condition.


Assuntos
Água Subterrânea , Poluentes Químicos da Água/análise , Monitoramento Ambiental , Ouro , Modelos Logísticos , Mineração , Nigéria , Reprodutibilidade dos Testes
15.
Sci Total Environ ; 738: 140382, 2020 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-32806349

RESUMO

Approximately 1.5 million individuals in Ontario are supplied by private water wells (private groundwater supplies). Unlike municipal supplies, private well water quality remains unregulated, with owners responsible for testing, treating, and maintaining their own water supplies. The primary goal of this study was to assess the effect of repeat sampling of private well water in Ontario and investigate the efficacy of geographically- and/or temporally specific testing recommendations and health risk assessments. The current study combines the Well Water Information System Dataset and the Well Water Testing Dataset from 2010 to 2017, inclusive. These two large existing province-wide datasets collated over an eight-year period were merged using an integrated spatial fuzzy logic and (next)- nearest neighbour approach. Provincial sampling data from 239,244 wells (702,861 samples) were analyzed for Escherichia coli to study the relationship between sampling frequency and Escherichia coli detection. Dataset variables were delineated based on hydrogeological setting (e.g. aquifer type, overburden depth, well depth, bedrock type) and seasonality to provide an in-depth understanding of Escherichia coli detection in private well water. Findings reveal differences between detection rates in consolidated and unconsolidated aquifers (p = 0.0191), and across seasons (p < 0.0001). The variability associated with Escherichia coli detection rates was explored by estimating sentinel sampling rates for private wells sampled three times, twelve times and twenty-four times per year. As sample size increases on an annual basis, so too does detection rate, highlighting the need to address current testing frequency guidelines. Future health risk assessments for private well water should consider the impact of spatial and temporal factors on the susceptibility of this drinking water source, leading to an increasingly accurate depiction of private well water contamination and the estimated effects on human health.


Assuntos
Água Potável , Água Subterrânea , Humanos , Ontário , Medição de Risco , Poços de Água
16.
Environ Monit Assess ; 192(9): 574, 2020 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-32772193

RESUMO

Central Kentucky could be considered a critical source area of nutrients in water ways because of low permeability soils, fast groundwater flow through bedrock fractures, and pervasive agriculture and development. Of particular concern is rising development in rural areas, which creates mixed land cover (MLC) watersheds, i.e., watersheds with development, agriculture, and other land cover types. MLC watersheds add complexity to spatial and temporal releases of dissolved constituents, leading to less predictable water quality patterns. The goal of this research was to examine the export of dissolved substances from a small, upland MLC catchment in central Kentucky with a focus on how the interaction between discharges from developed agricultural land cover and groundwater influence base flow water quality. Our approach was to spatially sample a representative catchment monthly over 1 year, characterize the major dissolved constituents, and evaluate catchment processes with statistical analyses and Piper diagrams. Principal component analysis, factor analysis, and Piper diagrams indicate base flow was composed of groundwater influenced by two different host rocks and an outfall draining a developed region. Base flow nutrient export was dominated by mixing nitrate-sulfate rich groundwater with ammonium-phosphate-chloride rich outfall drainage. High nitrate groundwater dominated nitrogen export in the winter, whereas high ammonium outfall drainage dominated summer export. Spatial analysis revealed that ~ 10% of the basin may have similar land cover and hydrologic processes, suggesting that MLC catchments are small but collectively significant nitrogen sources to river networks due to development and agriculturally impacted groundwater.


Assuntos
Água Subterrânea , Rios , Agricultura , Monitoramento Ambiental , Nutrientes
17.
Environ Monit Assess ; 192(9): 587, 2020 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-32813158

RESUMO

Morocco is basically a semiarid country with limited rainfall reducing the opportunities for rainfed agriculture. For feeding its ever growing population, irrigation is required. This study aims to evaluate the groundwater quality for irrigation in the Benslimane region by studying the main influencing chemical elements and characteristics. The main purpose is to provide the farmers and agricultural developers with a clear comprehension of the groundwater status. We focused on the determination and statistical analysis of physicochemical parameters and major elements (electrical conductivity, pH, Na+, K+,Ca2+, Mg2+, Cl-, SO42-, CO32-, and HCO3-) for 120 samples and the derivation of water quality indices like SAR, %Na, RSC, PI, KR, and MAR, along with graphical approaches such as Wilcox's and Richards's diagrams. Factors affecting groundwater hydrochemistry and quality were also discussed. The results show generally alkaline and shallow waters, with the majority of the samples belonging to the Na-Cl facies. Rock alteration, dissolution, ion exchange, evaporation, and anthropogenic activity are the main factors controlling water chemistry. Most prospected wells indicate high salinity problems due to salt water intrusion. With regard to the suitability of groundwater for irrigation, the majority of wells is of medium to poor quality and is therefore unsuitable. These types of water are found throughout the area, with a significant dominance on the coastal zone. The long-term use of this groundwater would therefore have negative impacts on soil quality and the sustainability of agricultural production. Therefore, we recommend proper agricultural management and irrigation practices in the Benslimane region, in order to increase agricultural production while preserving water and soil resources.


Assuntos
Água Subterrânea , Poluentes Químicos da Água/análise , Irrigação Agrícola , Agricultura , Monitoramento Ambiental , Marrocos , Qualidade da Água
18.
J Environ Manage ; 272: 111106, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32854896

RESUMO

Phreatophytic trees such as willows and poplars have a large capacity for extracting shallow groundwater, as evidenced by diurnal water table fluctuations corresponding to intensified transpiration during the day. As a result, they have been employed for phytoremediation of shallow contaminated groundwater. In this study, the water extraction (i.e. pumping) capacity of mature willows (Salix nigra) to capture shallow polluted groundwater in Belle Park, the site of a former landfill in Kingston, Ontario (Canada), was assessed using continuous field measurements of sap flow and water table levels associated with a single willow tree, combined with a transient numerical model (FEFLOW). On an annual basis, the sapflow averaged 2.3 m3d-1, with 70% of the cumulative sap flow occurring during the active growing season (May to September). The calibration showed a good fit (0.91 < R2<0.97) between measured groundwater levels from three shallow wells installed near the willow and the calculated water table level fluctuations, thus confirming that the water extraction rate based on sap flow data for the willow was appropriate. At stand level, additional modelling suggests that 3.4-4.7 ha of mature willows (i.e. between 7.8% and 10.6% of the Park area), could compensate for the current water volumes extracted by the municipality using a conventional pump and treat system. The results of this study indicate that willows can play a significant role in capturing contaminated groundwater underlying Belle Park, and potentially at other sites where removal of contaminants from shallow aquifers is desired.


Assuntos
Água Subterrânea , Salix , Biodegradação Ambiental , Ontário , Instalações de Eliminação de Resíduos
19.
Ecotoxicol Environ Saf ; 202: 110925, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800212

RESUMO

Chlorinated hydrocarbon contamination in soils and groundwater has a severe negative impact on the human health. Microbial reductive dechlorination is a major degradation pathway of chlorinated hydrocarbon in anaerobic subsurface environments, has been extensively studied. Recent progress on the diversity of the reductive dechlorinators and the key enzymes of chlororespiration has been well reviewed. Here, we present a thorough overview of the studies related to bioremediation of chloroethenes and polychlorinated biphenyls based on enhanced in situ reductive dechlorination. The major part of this review is to provide an up-to-date summary of functional microorganisms which are either detected during in situ biostimulation or applied in bioaugmentation strategies. The applied biostimulants and corresponding reductive dechlorination products are also summarized and the future research needs are finally discussed.


Assuntos
Biodegradação Ambiental , Hidrocarbonetos Clorados/metabolismo , Água Subterrânea , Halogenação , Bifenilos Policlorados , Cloreto de Vinil
20.
Ecotoxicol Environ Saf ; 202: 110915, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800250

RESUMO

Benzobicyclon is a systemic herbicide that was officially registered in China in 2018. The environmental behaviors of benzobicyclon hydrolysate (BH), the main metabolite and active product of benzobicyclon, remain poorly understood in paddy fields. Here, agricultural soil samples were collected from paddy fields in Jiangxi (Ferralsols), Shandong (Alisols), Hebei (Luvisols), Heilongjiang (Phaeozems), Zhejiang (Anthrosols), Sichuan (Gleysols), Hainan (Plinthosols), and Hubei (Lixisols) across China. The equilibrium oscillation method was used to study the adsorption-desorption behaviors of BH in the eight soils. The relationships between BH adsorption and soil physicochemical properties, environmental factors (temperature and initial solution pH), and other external conditions (addition of humic acid, biochar, and metal ions) were quantified. The adsorption-desorption parameters of BH in all soils were well fitted by the Freundlich model. The adsorption constant of BH varied between 0.066 and 4.728. The BH adsorption capacity decreased in the following order: Phaeozems > Alisols > Ferralsols > Lixisols > Plinthosols > Anthrosols > Luvisols > Gleysols. The Freundlich adsorption and desorption constants of BH were linearly positively correlated with soil clay content (R2 = 0.711 and 0.709; P = 0.009 and 0.009, respectively), organic carbon content (R2 = 0.684 and 0.672; P = 0.011 and 0.013, respectively), and organic matter content (R2 = 0.698 and 0.683; P = 0.010 and 0.011, respectively); however, their linear relationships with soil cation exchange capacity were not significant (R2 = 0.192 and 0.192; P = 0.278 and 0.278, respectively). The adsorption and desorption constants of BH had negative, albeit not significant, correlations with soil pH (R2 = 0.104 and 0.100; P = 0.437 and 0.445, respectively). The adsorption of BH by soil occurred spontaneously and was mainly based on physical adsorption. Either low or high temperature reduced the ability of the soil to adsorb BH. The addition of humic acid to the soil increased BH adsorption, while the addition of biochar increased the solution pH, resulting in decreased BH adsorption. Cation type and ionic strength also had strong effects on BH adsorption. With the exception of Phaeozems, BH exhibited intermediate or high mobility in the agricultural soils and thus poses risks to surface water and groundwater.


Assuntos
Compostos Bicíclicos com Pontes/química , Herbicidas/química , Poluentes do Solo/química , Sulfonas/química , Adsorção , Agricultura , China , Argila , Água Subterrânea , Herbicidas/análise , Solo/química , Poluentes do Solo/análise
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