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1.
Anomalous and natural concentrations of Cr 6+, occasionally exceeding the permitted limit for human consumption (0.05 mg/L), have been detected in groundwater in the northwestern region of the state of São Paulo. As part of a water-rock interaction investigation, this article describes the chemical and mineralogical characterization of rock samples taken from boreholes in the municipality of Urânia, with the objective of identifying Cr-bearing minerals and determining how chromium is associated with these minerals. Rock sample analysis were performed using X-ray Fluorescence, X-ray Diffraction, Scanning Electron Microscopy, electron microprobe and sequential extraction techniques. Chemical analyses indicated that the quartzose sandstones show a geochemical anomaly of chromium, with an average content of 221 ppm, which is higher than the reported chromium content of generic sandstones (35 ppm). Diopside was identified as the primary Cr-bearing mineral potentially subject to weathering processes, with a chromium content of up to 1.2% as Cr 2O 3. Many of the diopside grains showed dissolution features, confirming the occurrence of weathering. Sequential extraction experiments indicated that 99.3% of the chromium in samples is tightly bonded to minerals, whereas 0.24% is weakly bonded via adsorption. Assuming hypothetically that all adsorbed chromium is released via desorption, the theoretical Cr concentration in water would be one order of magnitude higher than the concentrations of Cr 6+ detected in groundwater. 相似文献
2.
The possible contamination of a groundwater system with industrial wastewater originating from a paper mill factory has been investigated in Piteå, N. Sweden. Six samples were collected from the wastewater in the waste dump and twelve samples from the adjacent groundwater were analyzed for chemistry and sulfur isotopes. The industrial wastewater is a saline water consisting mainly of Na–HCO 3–SO 4, having a high pH and showing δ 34S values between 7‰ and 9‰ affected by bacterial sulfate reduction. The groundwaters are relatively dilute, dominated by Na +, Ca 2+ and HCO 3−, but with varying concentrations as exemplified by sulfate with concentrations varying between 3 and 69 mg L − 1 while the δ 34S values range from − 0.5‰ to 14.3‰. The data suggest that the main S sources in the waters are the bedrock sulfides and/or atmospheric deposition, which, sometimes, are overlapped by bacterial sulfate reduction. Contamination from the waste dump does not occur. 相似文献
3.
Groundwater is a vital source for domestic and irrigation purposes in the loess area of Northwest China where climate is arid. However, the quality of groundwater in this area is deteriorating due to intensive industrial and agricultural activities, and this has a great adverse impact on human health. In order to better understand the pollution status of groundwater and the health risks to local residents, comprehensive water quality index was applied to assess the quality of drinking water in Yulin City, Northwest China, and sodium adsorption ratio, sodium percentage, residual sodium carbonate and permeability index were used to evaluate the quality of irrigation water. Moreover, the health risks caused by ingestion of groundwater were evaluated using the model proposed by the Ministry of Environmental Protection of the PR China. The results show that all groundwater samples for irrigation will not induce soil salinization, but more than half of them are not suitable for drinking, and Fe, Mn, TH, Mg 2+ and NO 3–N are the common contaminants which are mainly from natural processes, industrial and agricultural activities. The health risk assessment indicates that children face greater non-carcinogenic risk than adults. The order of contribution of contaminants to non-carcinogenic risk is NO 3 ? > As > F ? > Fe > Mn > Ba 2+ > Cr 6+ > Zn > NO 2 ?. The average carcinogenic risk of carcinogens (Cr 6+ and As) is 1.17 × 10 ?4 and 1.37 × 10 ?4 for adults and children, respectively, which surpasses the permissible level (1 × 10 ?6) stipulated by the Ministry of Environmental Protection of the PR China. Hence, effective measures are highly demanded to manage groundwater pollution and reduce the risks to human health. 相似文献
4.
The effects of multiple industrial-pollutant sources on the groundwater system were evaluated in the Industrial Development
Areas (IDAs) of Medak district, Andhra Pradesh (AP), India. The quality of groundwater in the region has been affected negatively
due to the discharge of effluents on open land and into ponds, tanks, and streams. Water samples from surface-water bodies,
dug wells,and bore wells were analyzed for their major ion concentrations. The high values of electrical conductivity (EC)
and concentrations of Na +, Ca 2+, Cl –, and HCO 3
– indicate the impact of industrial effluents. Based on the hydrochemistry, the groundwater is classified into various types,
such as sodium-chloride, sodium-bicarbonate, calcium-chloride, and magnesium-chloride, and its suitability for drinking and
irrigation has been assessed. The present studies made it possible to demarcate areas of contaminated groundwater and those
prone to contamination in the near future. Water in the area has deteriorated all along Nakka Vagu up to a maximum distance
of 500–700 m from the eastern bank. The groundwater quality in and around Patancheru (to a depth of 30 m) has become hazardous.
Some possible remedial measures are suggested.
Electronic Publication 相似文献
5.
Sukinda chromite valley is one of the largest chromite deposits of the country and produces nearly 8% of chromite ore. It
greatly contributes towards the economic development but at the same time deteriorates the natural environment. It is generally
excavated by opencast mining method. In the Sukinda mining area, around 7.6 million tons of solid waste have been generated
in the form of rejected minerals, overburden material/waste rock and sub-grade ore that may be resulting in environmental
degradation, mainly causing lowering in the water table vis-à-vis deterioration in surface and ground water quality. The study
conducted in and around one of the chromite mine of the valley reveals that the concentration of hexavalent chromium is found
in the water samples of ground and surface water, mine effluents and seepage water. Hexavalent Chromium (Cr +6) have been found varying between 0.02 mg/l and 0.12 mg/l in mine effluents and 0.03–0.8 mg/l in shallow hand pumps and 0.05
and 1.22 mg/l in quarry seepage. The concentration of Cr +6 in Damsal nalah, the main surface water source in the area, is found varying between 0.03 mg/l and 0.14 mg/l and a increasing
trend, which is in the downstream of mining activities, has been observed. Leachate study clearly shows that the soil lying
in the vicinity of mine waste dump shows highest concentration of Cr +6. Contaminant migration in ground water depends upon various geohydrological conditions of the area. The study shows that
aquifer resistivity varies between 15 Ωm to 150 Ωm and aquifer depth varies from 4 m to 26 m below ground level. The ground
water flow and mass transport models were constructed with the help of geo-hydrological and geophysical informations using
Visual Modflow software. Contaminant migration and path lines for 20 years have been predicted in two layers model of ground
water. The study provided an insight into the likely migration of contaminant in ground water due to leaching from overburden
dump of chromite ore and will be helpful in making strategic planning for limiting the contaminant migration in the ground
water regime in and around the mining areas. 相似文献
6.
Comparison of polarized optical absorption spectra of natural Ca-rich diopsides and synthetic NaCrSi 2O 6 and LiCrSi 2O 6 clinopyroxenes, evidences as vivid similarities, as noticeable differences. The similarities reflect the fact that in all
cases Cr 3+ enters the small octahedral M1-site of the clinopyroxene structure. The differences are due to some iron content in the natural
samples causing broad intense near infrared bands of electronic spin-allowed dd transitions of Fe 2+(M1, M2) and intervalence Fe 2+/Fe 3+ charge-transfer transition, and by different symmetry and different local crystal fields strength of Cr 3+ in the crystal structures. The positions of the spin-allowed bands of Cr 3+, especially of the low energy one caused by the electronic 4
A
2g → 2
T
1g transition, are found to be in accordance with mean M1–O distances. The local relaxation parameter ε calculated for lim Cr
3+ → 0 from the spectra and interatomic
á Cr - O
ñ \left\langle {Cr - O} \right\rangle and
á Mg - O
ñ \left\langle {Mg - O} \right\rangle distances yields a very high value, 0.96, indicating that in the clinopyroxene structure the local lattice relaxation around
the “guest” ion, Cr 3+, deviates greatly from the “diffraction” value, ε = 0, than in any other known Cr 3+-bearing systems studied so far. Under pressure the spin-allowed bands of Cr 3+ shift to higher energies and decrease in intensity quite in accordance with the crystal field theoretical expectations, while
the spin-forbidden absorption lines remain practically unshifted, but also undergo a strong weakening. There is no evident
dependence of the Racah parameter B of Cr 3+ reflecting the covalence of the oxygen-chromium bond under pressure: within the uncertainty of determination it may be regarded
as practically constant. The values of CrO 6 octahedral modulus,
k\textpoly\textloc k_{\text{poly}}^{\text{loc}} , derived from high-pressure spectra of natural chromium diopside and synthetic NaCrSi 2O 6 kosmochlor are very close, ~203 and ~196 GPa, respectively, being, however, nearly twice higher than that of MgO 6 octahedron in diopside, 105(4) GPa, obtained by Thompson and Downs ( 2008). Such a strong stiffening of the structural octahedron, i.e. twice higher value of
k\textCr3 + \textloc k_{{{\text{Cr}}^{3 + } }}^{\text{loc}} comparing with that of
k\textMg2 + \textloc k_{{{\text{Mg}}^{2 + } }}^{\text{loc}} , may be caused by simultaneous substitution of Ca 2+ by larger Na + in the neighboring M2 sites at so-called jadeite-coupled substitution Mg 2+ + Ca 2+ → Cr 3+ + Na +. It is also remarkable that the values of CrO 6 octahedral modulus of NaCrSi 2O 6 kosmochlor obtained here are nearly twice larger than that of 90(16) GPa, evaluated by high-pressure X-ray structural refinement
by Origlieri et al. ( 2003). Taking into account that the overall compressibility of the clinopyroxene structure should mainly be due to the compressibility
of M1- and M2-sites, our
k\textCr3 + \textloc k_{{{\text{Cr}}^{3 + } }}^{\text{loc}} -value, ~196 GPa, looks much more consistent with the bulk modulus value, 134(1) GPa. 相似文献
7.
The overexploitation of groundwater in some parts of the country induces water quality degradation. The untreated industrial effluents discharged on the surface causes severe groundwater pollution in the industrial belt of the country. This poses a problem of supply of hazard free drinking water in the rural parts of the country. There are about 80 tanneries operating in and around Dindigul town in upper Kodaganar river basin, Tamilnadu, India. The untreated effluents from the tanneries have considerably affected the quality of groundwater in this area. To assess the extent of groundwater deterioration, a detailed analysis of groundwater quality data has been carried out. The concentration of cations such as Calcium (Ca 2+), Magnesium (Mg 2+), Sodium (Na +) and Potassium (K +), and anions such as Bicarbonate (HCO 3–), Sulphate (SO 42–), Chloride (Cl –) and Nitrate (NO 3–) in the groundwater have been studied. Apart from these constituents, pH, electrical conductivity (EC), total dissolved solid and total hardness (TH as CaCO 3) were also studied. The correlation of these constituents with the EC has been carried out. The highest correlation is observed between EC and chloride with a correlation coefficient of 0.99. Progressive reduction in correlation coefficients for Mg 2+, (Na + + K +), Ca 2+ and SO 42– are observed as 0.91, 0.87, 0.86 and 0.56, respectively. It is found that the quality of groundwater in the area under investigation is deteriorated mainly due to extensive use of salt in the leather industries. 相似文献
8.
Chromium-doped titanite and malayaite samples, which were synthesised to evaluate their performance as ceramic pigments, show remarkable photoluminescence behaviour. Emissions of centres related to traces of trivalent rare-earth elements (REE) are observed exclusively from chromium-free samples. Their Cr-doped analogues (containing the same REEs on the same concentration levels), in contrast, only show broad-band Cr 3+ emission whereas all REE emissions are suppressed. This behaviour is assigned to quenching of REE emissions by chromium centres (i.e., REE 3+ → Cr 3+ energy transfer). 相似文献
9.
This paper analyses flow and transport of pesticides from the unsaturated zone to groundwater so as to predict concentration
of those contaminants in the Fucino Plain’s groundwater, by site investigations and numerical simulations. Pesticides were
detected in surface water (peaks of 13 μg L −1) and groundwater (peaks of 0.37 μg L −1). Modelling tools made it possible to identify that pattern of precipitation, organic matter content, and root thickness
are the key factors involved in vertical seepage of pesticides. Numerical simulations indicated that a significant fraction
of contaminants is leached from the most surficial soil layers through runoff, while only a secondary fraction is mobilised
towards groundwater. Likelihood of contaminating deep groundwater is fairly low, whereas surface waters show higher susceptibility.
Results of the proposed conceptual hydrogeological model show that pesticides are more likely to be entrained by mixing of
stream water with shallow groundwater in periods of high water exploitation from shallow wells. 相似文献
10.
Electron paramagnetic resonance (EPR) study of single crystals of chromium-doped forsterite grown by the Czochralski method
in two different research laboratories has revealed, apart from the known paramagnetic centers Cr 3+( M1), Cr 3+( M2) and Cr 4+, a new center
\text Cr 3+ ( M 1)- V\textMg 2+ ( M 2) {\text{Cr}}^{ 3+ } (M 1){-}V_{{{\text{Mg}}^{ 2+ } }} (M 2) formed by a Cr 3+ ion substituting for Mg 2+ at the M1 structural position with a nearest-neighbor Mg 2+ vacancy at the M2 position. For this center, the conventional zero-field splitting parameters D and E and the principal g values and A values of the 53Cr hyperfine splitting have been determined as follows: D = 33.95(3) GHz, E = 8.64(1) GHz, g = [1.9811(2), 1.9787(2), 1.9742(2)], A = [51(3), 52(2), 44(3)] MHz. The center has been identified by comparing EPR spectra with those of the charge-uncompensated
ion Cr 3+( M1) and the ion pair Cr 3+( M1)–Li +( M2) observed in forsterite crystals codoped with chromium and lithium. It has been found that the concentration of the new
center decreases to zero, whereas that of the Cr 3+( M1) and Cr 3+( M1)–Li +( M2) centers increases with an increase of the Li content from 0 up to ~0.03 wt% (at the same Cr content ~0.07 wt%) in the melt.
The known low-temperature luminescence data pertinent to the centers under consideration are also discussed. 相似文献
11.
Industrial wastewater is characterised by the presence of a great quantity of metallic micro-pollutants, among which chromium
by its mobility, contaminates the surface and groundwater. The study of different aquifers within the area of Annaba (Algeria)
shows extremely variable chromium concentrations in the unconfined aquifer (0–0.22 mg l −1), which becomes practically null in dry period; on the other hand, they remain relatively constant in the deep confined aquifer
(about 0.04 mg l −1). To specify the mechanisms of chromium migration in the aquifer system, a study of space–time evolution of chromium concentrations
in unconfined aquifer was undertaken, while considering the kinetics of diffusion in the deeper aquifer. Chromium, indirectly
reduced microbiologically by sulphate-reducer bacteria in the upper aquifer, is likely to anticipate the auto-depuration capacity
of the ground and to reduce the quality of groundwater. 相似文献
12.
Present study is an effort to distinguish between the contributions of natural weathering and anthropogenic inputs towards
high salinity and nutrient concentrations in the groundwater of National Capital Territory (NCT) Delhi, India. Apart from
the source identification, the aquifer of entire territory has been characterized and mapped on the basis of salinity in space
and water suitability with its depth. Major element chemistry, conventional graphical plots and specific ionic ratio of Na +/Cl −, SO 4
2−/Cl −, Mg 2+/Ca 2+ and Ca 2+/(HCO 3
− + SO 4
2−) are conjointly used to distinguish different salinization sources. Results suggest that leaching from the various unlined
landfill sites and drains is the prime cause of NO 3
− contamination while study area is highly affected with inland salinity which is geogenic in origin. The seasonal water level
fluctuation and rising water level increases nutrients concentration in groundwater. Mixing with old saline sub-surface groundwater
and dissolution of surface salts in the salt affected soil areas were identified as the principle processes controlling groundwater
salinity through comparison of ionic ratio. Only minor increase of salinity is the result of evaporation effect and pollution
inflows. The entire territory has characterized into four groups as fresh, freshening, near freshening and saline with respect
to salinity in groundwater. The salinity mapping suggests that in general, for drinking needs, groundwater in the fresh, freshening
and near freshening zone is suitable up to a depth of 45, 20 and 12 m, respectively, while the saline zones are unsuitable
for any domestic use. In the consideration of increasing demand of drinking water in the area; present study is vital and
recommends further isotopic investigations and highlights the need of immediate management action for landfill sites and unlined
drains. 相似文献
13.
León valley, located in the Mexican state of Guanajuato, has a long history (35+ a) of Cr contamination of groundwater and surface water. Here data are presented for Cr, major ion and trace element concentrations and Cr stable isotope measurements of groundwater in a heavily contaminated aquifer in Buenavista, where Cr ore processing residue piles (COPRPs) located in a chromate production factory are the main source of Cr. The aquifer directly beneath the factory still retains very high Cr(VI) concentrations (∼121 mg/L). Ongoing pump and treat remediation is keeping the high concentration plume confined to the factory area and immediate vicinity, though Cr is also detected at some distance away. Chromium isotope data of the aquifer directly under the factory show only a small increase in δ 53Cr (+0.33‰ to +0.81‰) and indicates minimal reduction of Cr(VI) to Cr(III). Very high Cr(VI) concentrations have possibly overwhelmed natural reductants and furthermore fresh Cr(VI) was being leached into the groundwater from the COPRP. From just one year of Cr isotope data it is clear that more aggressive remediation techniques will be necessary to reduce or eliminate the contamination. The fringes of the Cr plume have substantially lower concentrations and can be partially explained by transport of the main plume or mixing between waters from the nearby landfill and highly contaminated waters from QC. While the source of Cr at the fringes of the plume could be attributed to a source from the nearby landfill instead of the main plume from the factory, the Cr stable isotope data show enrichment in the heavier isotopes and point to varying amounts of reduction. Isotopic enrichment seen between 2007 and 2008 along the fringe may indicate either reduction or less unreacted Cr(VI) is being transported to the fringes. In either case some potential for natural attenuation of Cr(VI) exists at the western margin of the plume with the landfill playing a role. 相似文献
14.
Geochemical processes that take place in the aquifer have played a major role in spatial and temporal variations of groundwater
quality. This study was carried out with an objective of identifying the hydrogeochemical processes that controls the groundwater
quality in a weathered hard rock aquifer in a part of Nalgonda district, Andhra Pradesh, India. Groundwater samples were collected
from 45 wells once every 2 months from March 2008 to September 2009. Chemical parameters of groundwater such as groundwater
level, EC and pH were measured insitu. The major ion concentrations such as Ca 2+, Mg 2+, Na +, K +, Cl −, and SO 4
2− were analyzed using ion chromatograph. CO 3
− and HCO 3
− concentration was determined by acid–base titration. The abundance of major cation concentration in groundwater is as Na + > Ca 2+ > Mg 2+ > K + while that of anions is HCO 3
− > SO 4
2− > Cl − > CO 3
−. Ca–HCO 3, Na–Cl, Ca–Na–HCO 3 and Ca–Mg–Cl are the dominant groundwater types in this area. Relation between temporal variation in groundwater level and
saturation index of minerals reveals the evaporation process. The ion-exchange process controls the concentration of ions
such as calcium, magnesium and sodium. The ionic ratio of Ca/Mg explains the contribution of calcite and dolomite to groundwater.
In general, the geochemical processes and temporal variation of groundwater in this area are influenced by evaporation processes,
ion exchange and dissolution of minerals. 相似文献
15.
The karst groundwater system is extremely vulnerable and easily contaminated by human activities.To understand the spatial distribution of contaminants in the groundwater of karst urban areas and contributors to the contamination,this paper employs the spatial information statistics analysis theory and method to analyze the karst groundwater environment in Guiyang City.Based on the karst ground water quality data detected in 61 detection points of the research area in the last three years,we made Kriging evaluation isoline map with some ions in the karst groundwater,such as SO4 2-,Fe 3+,Mn 2+and F -,analyzed and evaluated the spatial distribution,extension and variation of four types of ions on the basis of this isoline map.The results of the analysis show that the anomaly areas of SO4 2-,Fe 3+,Mn 2+,Fand other ions are mainly located in Baba’ao,Mawangmiao and Sanqiao in northwestern Gui- yang City as well as in its downtown area by reasons of the original non-point source pollution and the contamination caused by human activities(industrial and domestic pollution). 相似文献
16.
The hydrogeochemistry of groundwater and environmental aspects of the Tanjero area (Sulaimani City, Kurdistan region, Iraq) were investigated statistically. Correlation analysis and cluster analysis revealed several indicators for the source of contaminations. The hydrochemical classification of the water samples determined Ca 2+, Na +, and Mg 2+ as dominant ions and K/Rb and Na/Cl ratios indicated water–rock interactions with several minerals (e.g., silicate and carbonate minerals). Sr, Ca, Mg, Rb, and K (1757, 117, 29.8, 7.23, and 10.1 μg/L, respectively) in the water samples correlate with each other and show higher concentrations in the wells around scrape and dump sites than the other wells. The water samples were classified according to a redox classification as well, and aerobic and intermediate anaerobic categories were recognized with regard to the reduction of dissolved oxygen and Mn (VI) ions with organic matter in the groundwater. Mn exceeds drinking water standards. 相似文献
17.
Groundwater down-gradient from a mine rock dump in Dalarna, Sweden was sampled from the onset of snowmelt runoff (April) until October in order to investigate seasonal variations in groundwater composition. The results demonstrate that considerable variation in solute concentration (Al, Cu, Fe, SO 42−, Zn) and acidity occurs in groundwater; the greatest change in solute concentrations occurs during the melting of the snow cover, when sulfide oxidation products are flushed from the rock dump. During this period, groundwater flow is concentrated near the soil surface with an estimated velocity of 1 m/day. Groundwater acidity varied by a factor of four closest to the rock dump during the sampling period, but these variations were attenuated with distance from the rock dump. Over a distance of 145 m, groundwater pH increases from 2.5 to 4.0 and acidity decreases from 3–13 to 0.8–1.1 meq/L, which is the combined effect of ferric iron precipitation and aluminosilicate weathering. As a result of flushing from the upper soil horizons, peaks in total organic carbon and ammonium concentrations in groundwater are observed at the end of snowmelt. In soils impacted by acidic surface runoff, the sequential extraction of C horizon soils indicates the accumulation of Cu in well-crystallized iron oxyhydroxides in the upper C horizon, while Cu, Fe, Ni and Zn accumulate in a well-crystallized iron oxyhydroxide hardpan that has formed 2.5m below the ground surface. Surface complexation modeling demonstrates that SO 42− and Cu adsorb to the abundant iron oxyhydroxides at pH < 4, while Zn adsorption in this pH range is minimal. 相似文献
18.
The gold mining process at Kolar gold field (KGF) mines has generated about 32 million tons of tailings. Gold was extracted
from the mined ores using cyanidation technique that involved dissolution of gold in the ore by water soluble alkali metal
cyanides (example, sodium cyanide or potassium cyanide). Of the several dumps that received the mine tailings only the Kennedy’s
Line dump was active prior to closure of the KGF mines in the year 2000. The Kennedy’s Line dump received sulfide bearing
tailings in slurry form that comprised of spent ore and process water bearing soluble alkali metal cyanide. Depending on the
pH of the tailing slurry, the free cyanides may exist as aqueous hydrogen cyanide that can escape to the atmosphere as hydrogen
cyanide gas or occur as soluble cyanide (CN −) ions that can be leached by infiltrating water to the sub-surface environment. Additionally, the presence of pyrite minerals
in the Kennedy’s Line dump makes them susceptible to acid drainage. This study examines the potential of gold tailings of
Kennedy’s Line dump to release cyanide ions (CN −) and acid drainage to the sub-surface environment by performing physico-chemical and leaching tests with tailing samples
collected from various depths of the dump, sub-surface soil samples beneath the dump and groundwater samples from vicinity
of Kennedy’s Line dump. The chemical mechanisms responsible for the ambient cyanide and pH levels of the tailing dump, sub-surface
soil samples and groundwater are also inferred from the laboratory results. 相似文献
19.
Intensive use of land resources in arid and semi-arid regions exert serious pressures on groundwater resources and jeopardize
further socio-economical developments. The Amman-Zarqa Basin (AZB), the most vital basin in Jordan, is facing recent groundwater
deterioration due to a very large increase in water demands for domestic, agricultural, and industrial uses. The objectives
of this paper were to quantify the degree of contamination in the basin by evaluating the characteristics, distribution and
seasonal variations of two pollution indicators (nitrate concentration and salinity) and to determine the impacts of human
activities (land use) on groundwater quality. Based upon long-term data (1970–2005) of groundwater samples collected from
538 wells across the AZB, spatial analyses indicated that both indicators have a strong spatial dependence and are anisotropically
distributed. Prediction maps of Ordinary Kriging and Indicator Kriging provided detailed indications of the major and minor
sources of pollution in the basin. Inefficient wastewater treatment plants, industrial activities and agricultural practices
were responsible for 91, 85, and 25% salinization of nearby wells, respectively. Nitrate pollution had reached 73% above threshold
(50 mg/L) in some cases. The temporal analyses estimated the salinity buildup rate to be around 8 × 10 −2 μS/cm per day, while nitrate buildup rate was estimated to be around 6 × 10 −2 mg/L per day. Remote sensing and spatial analyses helped greatly in groundwater quality assessment not only in providing
the environmental status of the AZB but also in delineating the potential of contamination risk zones and their correlation
to human activities. Furthermore, the paper suggests some environmental protection strategies that should be adopted to protect
the vital groundwater resources of the basin from further deterioration. 相似文献
20.
Urban areas are major contributors to the alteration of the local atmospheric and groundwater environment. The impact of such changes on the groundwater thermal regime is documented worldwide by elevated groundwater temperature in city centers with respect to the surrounding rural areas. This study investigates the subsurface urban heat island (SUHI) in the aquifers beneath the Milan city area in northern Italy, and assesses the natural and anthropogenic controls on groundwater temperatures within the urban area by analyzing groundwater head and temperature records acquired in the 2016–2020 period. This analysis demonstrates the occurrence of a SUHI with up to 3 °C intensity and reveals a correlation between the density of building/subsurface infrastructures and the mean annual groundwater temperature. Vertical heat fluxes to the aquifer are strongly related to the depth of the groundwater and the density of surface structures and infrastructures. The heat accumulation in the subsurface is reflected by a constant groundwater warming trend between +0.1 and?+?0.4 °C/year that leads to a gain of 25 MJ/m2 of thermal energy per year in the shallow aquifer inside the SUHI area. Future monitoring of groundwater temperatures, combined with numerical modeling of coupled groundwater flow and heat transport, will be essential to reveal what this trend is controlled by and to make predictions on the lateral and vertical extent of the groundwater SUHI in the study area. 相似文献
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