Groundwater quality usually correlated with different land use types. As Britain’s second largest aquifer, the Sherwood Sandstone is confronted by the threat of high nitrate concentrations caused by ...intensive agricultural activities. The aim of this study is to estimate nitrogen loss on the aquifer outcrop and to predict nitrate concentration in groundwater in the future appropriately. GIS was used in the study for spatial analysis of land use data, pre-processing nitrate inputs for a groundwater model. An export coefficient model was adopted to help estimation of nitrogen losses in the study area. A groundwater flow and mass transport model was constructed and calibrated to groundwater level in 45 monitoring points and nitration concentration in 22 public supply boreholes, respectively. Then, the calibrated model was used to predict nitrate concentrations in groundwater boreholes to explore nitrate trend in the future under current land use mode and agricultural practice. The simulative results show that even if some moderate mitigation methods are adopted, nitrate concentrations in boreholes would increase in the future (before eventually decreasing) and fail to meet water quality standards (50 mg NO
3
/L). The nitrate concentration would reach 73 mg L
−1
in selected borehole by December 2025 unless more radical changes in land use were adopted. It is concluded that a time scale of several decades may be considered for the sandstone aquifer in the context of nutrient management and nitrate mitigation in order to achieve improvements in water quality.
Previous studies attribute abnormal boron (B) levels in streams and groundwaters to wastewater and fertilizer inputs. This study shows that municipal drinking water used for lawn irrigation ...contributes substantial non-point loads of B and other chemicals (S-species, Li, and Cu) to surface waters and shallow groundwaters in the St. Louis, Missouri, area. Background levels and potential B sources were characterized by analysis of lawn and street runoff, streams, rivers, springs, local rainfall, wastewater influent and effluent, and fertilizers. Urban surface waters and groundwaters are highly enriched in B (to 250μg/L) compared to background levels found in rain and pristine, carbonate-hosted streams and springs (<25μg/L), but have similar concentrations (150 to 259μg/L) compared to municipal drinking waters derived from the Missouri River. Other data including B/SO42-−S and B/Li ratios confirm major contributions from this source. Moreover, sequential samples of runoff collected during storms show that B concentrations decrease with increased discharge, proving that elevated B levels are not primarily derived from combined sewer overflows (CSOs) during flooding. Instead, non-point source B exhibits complex behavior depending on land use. In urban settings B is rapidly mobilized from lawns during “first flush” events, likely representing surficial salt residues from drinking water used to irrigate lawns, and is also associated with the baseflow fraction, likely derived from the shallow groundwater reservoir that over time accumulates B from drinking water that percolates into the subsurface. The opposite occurs in small rural watersheds, where B is leached from soils by recent rainfall and covaries with the event water fraction.
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► Boron sources and loads differ between urban and rural watersheds. ► Wastewaters are not the major boron source in small St. Louis, MO watersheds. ► Municipal drinking water used for lawn irrigation can be high in boron. ► Lawn irrigation practices can considerably alter urban water chemistry.
In present study total arsenic, inorganic arsenic species and fluoride ion contaminations in underground water of Diplo and Chachro sub district of Tharparkar, Pakistan were investigated. The ...concentrations of total As, inorganic As species, F− and others physicochemical parameters were reported in terms of basic statistical parameters, principal component analysis, cluster analysis, sodium absorption ratio and saturation indices. The As3+ was determined by cloud point extraction using ammonium pyrrolidinedithiocarbamate (APDC) as complexing reagent, and complex was extracted by surfactant-rich phases in the non-ionic surfactant Triton X-114; after centrifugation the surfactant-rich phase was diluted with 0.1 mol/L HNO3 in methanol. While total inorganic arsenic (iAs) was determined by solid phase extraction using titanium dioxide (TiO2) as an adsorbent, after centrifugation, the solid phase was prepared to be slurry for determination. The extracted As species were determined by electrothermal atomic absorption spectrometry. The concentration of As5+ in the water samples was calculated by the difference of the total iAs and As3+, while F− and other anions were determined by ion chromatography. The positive correlation of F− and As species with Na+ and HCO3− showed that the water with high salinity and alkalinity stabilized the As species and F− in the groundwater. The positive correlation (r = 0.640, p = 0.671) was observed between total As and it species with F−. Results showed that underground water samples of these two areas of Tharparkar were severely contaminated with arsenic and fluoride ion, which are exceeded the World Health Organization (WHO) provisional guideline value, and United States Environmental Protection Agency, maximum contaminant level of 0.01 mg/L and 1.5 mg/L, respectively.
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► Simultaneously evaluated the contamination of F− and arsenic in underground water. ► Speciation of arsenic by cloud point and solid phase extraction methods. ► Application of multivariate statistical methods for groundwater quality assessment. ► Correlation of As and F− with other physicochemical parameters was carried out.
Compound-specific analysis of stable carbon and hydrogen isotopes was used to assess the fate of the gasoline additive methyl tert-butyl ether (MTBE) and its major degradation product tert-butyl ...alcohol (TBA) in a groundwater plume at an industrial disposal site. We present a novel approach to evaluate two-dimensional compound-specific isotope data with the potential to identify reaction mechanisms and to quantify the extent of biodegradation at complex field sites. Due to the widespread contaminant plume, multiple MTBE sources, the presence of numerous other organic pollutants, and the complex biogeochemical and hydrological regime at the site, a traditional mass balance approach was not applicable. The isotopic composition of MTBE steadily changed from the source regions along the major contaminant plume (−26.4‰ to +40.0‰ (carbon); −73.1‰ to +60.3‰ (hydrogen)) indicating substantial biodegradation. Constant carbon isotopic signatures of TBA suggest the absence of TBA degradation at the site. Published carbon and hydrogen isotope fractionation data for biodegradation of MTBE under oxic and anoxic conditions, respectively, were examined and used to determine both the nature and the extent of in-situ biodegradation along the plume(s). The coupled evaluation of two-dimensional compound-specific isotope data explained both carbon and hydrogen fractionation data in a consistent way and indicate anaerobic biodegrada tion of MTBE along the entire plume. A novel scheme to reevaluate empiric isotopic enrichment factors (ε) in terms of theoretically based intrinsic carbon (12 k/13 k) and hydrogen (1 k/2 k) kinetic isotope effects (KIE) is presented. Carbon and hydrogen KIE values, calculated for different potential reaction mechanisms, imply that anaerobic biodegradation of MTBE follows a SN2-type reaction mechanism. Furthermore, our data suggest that additional removal process(es) such as evaporation contributed to the overall MTBE removal along the plume, a phenomenon that might be significant also for other field sites at tropic or subtropic climates with elevated groundwater temperatures (25°C).
The ground water quality of District Nainital (Uttarakhand, India) has been assessed to see the suitability of ground water for drinking and irrigation applications. This is a two-part series paper ...and this paper examines the suitability of ground water including spring water for drinking purposes. Forty ground water samples (including 28 spring samples) were collected during pre- and post-monsoon seasons and analyzed for various water quality constituents. The hydrochemical and bacteriological data was analyzed with reference to BIS and WHO standards and their hydrochemical facies were determined. The concentration of total dissolved solids exceeds the desirable limit of 500 mg/L in about 10% of the samples, alkalinity values exceed the desirable limit of 200 mg/L in about 30% of the samples, and total hardness values exceed the desirable limit of 300 mg/L in 15% of the samples. However, no sample crosses the maximum permissible limit for TDS, alkalinity, hardness, calcium, magnesium, chloride, sulfate, nitrate, and fluoride. The concentration of chloride, sulfate, nitrate, and fluoride are well within the desirable limit at all the locations. The bacteriological analysis of the samples does not show any sign of bacterial contamination in hand pump and tube-well water samples. However, in the case of spring water samples, six samples exceed the permissible limit of ten coliforms per 100 ml of sample. It is recommended that water drawn from such sources should be properly disinfected before being used for drinking and other domestic applications. Among the metal ions, the concentration of iron and lead exceeds the permissible limit at one location whereas the concentration of nickel exceeds the permissible limit in 60 and 32.5% of the samples during pre- and post-monsoon seasons, respectively. The grouping of samples according to their hydrochemical facies indicates that majority of the samples fall in Ca-Mg-HCO₃ hydrochemical facies.
Concentrations of As and other trace elements and their association were examined in groundwater (
n=25) and human hair (
n=59) collected at Gia Lam District and Thanh Tri District, suburban areas of ...Hanoi, Vietnam, in September 2001. Concentrations of As in the groundwater ranged from <0.10 to 330 μg/l, with about 40% of these exceeding WHO drinking water guideline of 10
μg/l. Also, 76% and 12% of groundwater samples had higher concentrations of Mn and Ba than WHO drinking water guidelines, respectively. Arsenic concentrations in hair of residents in Gia Lam and Thanh Tri Districts (range 0.088–2.77
μg/g dry wt.) were lower than those in other As-contaminated areas of the world, but were higher than those of people in non-contaminated areas. Concentrations of As and Mn in hair of some individuals from the Gia Lam and Thanh Tri Districts exceeded the level associated with their toxicity and, therefore, a potential health risk of As and Mn is a concern for the people consuming the contaminated water in this area. Cumulative As exposure was estimated to be lower than the threshold levels at the present, which might explain the absence of manifestations of chronic As poisoning and arsenicosis in the residents of Gia Lam and Thanh Tri Districts. To our knowledge, this study revealed for the first time that the residents are exposed not only to As but also Mn and Ba from groundwater in the Red River Delta, Vietnam.
High concentrations of arsenic, manganese and barium were found in tube-well water and human hair in suburban areas of Hanoi, Vietnam.
Millions of people in Bangladesh have probably switched their water consumption to wells that meet the local standard for As in drinking water of 50 μg/L as a result of blanket field testing ...throughout the country. It is therefore important to know if As concentrations in those wells could change over time. To address this issue, we report here precise groundwater As analyses for time-series samples collected from a suite of 20 tube wells containing ≤50 μg/L As and ranging from 8 to 142 m in depth. For 17 out of 20 wells, the standard deviation of groundwater As concentrations was <10 μg/L over the 3-year monitoring period (n = 24−44 per well). Six of the 17 wells are community wells, each of which serves the needs of several hundred people in particularly affected villages. Of the three wells showing larger fluctuations in chemical composition including As, two are very shallow (8 and 10 m). Variations in As concentrations for one of these wells (50 ± 32 μg/L, n = 36), as well as another shallow well showing smaller variations (48 ± 5 μg/L, n = 36), appear to be coupled to seasonal precipitation and recharge linked to the monsoon. The other shallow well showing larger variations in composition indicates a worrisome and steady increase in As concentrations from 50 to 70 μg/L (n = 36) over 3 years. The time series of As (30 ± 11 μg/L, n = 24) and other constituents in one deep community well (59 m) show large fluctuations that suggest entrainment of shallow groundwater through a broken PVC pipe. Even though the majority of wells that were initially safe remained so for 3 years, our results indicate that tube wells should be tested periodically.
There has been considerable progress in developing treatment systems for point sources of minewater pollution in recent years; however, there remains a knowledge gap in the characterisation and ...remediation of diffuse minewater sources. Data are presented from the River Gaunless catchment, a historically heavily coal mined catchment in the northeast of England. Instream iron (Fe) loadings were monitored alongside loadings arising from point minewater discharges over a 12-month period to assess the dynamic importance of diffuse sources of minewater pollution. In low flow, diffuse sources account for around 50% of instream loading, a proportion which increases to 98% in high flow conditions. The low flow sources appear to be dominated by direct discharge of contaminated groundwater to surface waters in lower reaches of the catchment. In high flow, resuspended Fe-rich sediments, which are both naturally occurring and derived from historic mining, become the dominant diffuse source of Fe in the water column.
Diffuse sources of minewater pollution significantly contribute to instream contaminant loadings under varying flow conditions.
The reverse osmosis (RO) technology offers a solution for the shortage of pristine water resources worldwide, through its capacity on treating all water kinds such as seawater, wastewater, ground ...water and surface water. The main concern in using RO technology for water treatment is fouling problems, and in particular biofouling. Biofouling negatively affects the quality of RO product and renders RO a costly technology for water treatment. The key solution to reduce the risk of biofouling in RO system lies in understanding the process of biofouling formation, choosing an adequate biofilm monitoring technique and applying effective biofouling control treatment for the RO membrane system. In this paper, the mechanisms of microbial adhesion to RO membrane are illustrated along with the key factors that influence the microbial adhesion process. In addition to that, the common strategies for biofilm monitoring in water flow systems are reviewed with highlighting applications, advantages and disadvantages of each strategy. The common biofouling control methods for reducing the formation of biofouling in the RO system are also presented in this paper. The application of the environmentally friendly physical disinfection techniques for biofouling control in the RO membrane system is suggested in this paper.
► The mechanisms and the fundamentals of microbial adhesion to membrane surface were elaborated. ► Microscopic, spectroscopic and other biofouling monitoring techniques were reviewed. ► The advantages and disadvantages associated with using the common biofouling monitoring techniques were discussed. ► Different technical aspects of the available biofouling controlling methods were addressed. ► The use of environmentally friendly disinfection methods for biofouling controlling in membrane system was proposed.
We developed a process-based model to predict the probability of arsenic exceeding 5 μg/L in drinking water wells in New England bedrock aquifers. The model is being used for exposure assessment in ...an epidemiologic study of bladder cancer. One important study hypothesis that may explain increased bladder cancer risk is elevated concentrations of inorganic arsenic in drinking water. In eastern New England, 20−30% of private wells exceed the arsenic drinking water standard of 10 micrograms per liter. Our predictive model significantly improves the understanding of factors associated with arsenic contamination in New England. Specific rock types, high arsenic concentrations in stream sediments, geochemical factors related to areas of Pleistocene marine inundation and proximity to intrusive granitic plutons, and hydrologic and landscape variables relating to groundwater residence time increase the probability of arsenic occurrence in groundwater. Previous studies suggest that arsenic in bedrock groundwater may be partly from past arsenical pesticide use. Variables representing historic agricultural inputs do not improve the model, indicating that this source does not significantly contribute to current arsenic concentrations. Due to the complexity of the fractured bedrock aquifers in the region, well depth and related variables also are not significant predictors.
