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1.
Abstract
Determination of chemical constituent ratios allows distinction between two salinization mechanisms responsible for shallow saline ground water and vegetative-kill areas in parts of west Texas. Mixing of deep-basin (high Cl) salt water and shallow (low Cl) ground water results in saline waters with relatively low Ca/Cl, Mg/Cl, SO44/ Cl, Br/Cl, and NO3/Cl ratios. In scattergrams of major chemical constituents vs. chloride, plots of these waters indicate trends with deep-basin brines as high Cl end members. Evaporation of ground water from a shallow water table, in contrast, results in saline water that has relatively high Ca/Cl, Mg/Cl, SO4/Cl, and Br/CL ratios. Trends indicated by plots of this water type do not coincide with trends indicated by plots of sampled brines. Leaching of soil nitrate in areas with a shallow water table accounts for high NO3 concentrations in shallow ground water.  相似文献   

2.
Nitrate-contaminated ground water beneath and adjacent to an intensive swine ( Sus scrofa domesticus ) production facility in the Middle Coastal Plain of North Carolina was analyzed for δ15N of nitrate (δ15N-NO3). Results show that the isotopic signal of animal waste nitrogen is readily identifiable and traceable in nitrate in this ground water. The widespread land application of animal wastes from intensive livestock operations constitutes a potential source of nitrogen contamination to natural water throughout large regions of the United States and other countries. The site of the present study has been suspected as a nitrate contamination source to nearby domestic supply wells and has been monitored for several years by government and private water quality investigators through sampling of observation wells, ditches, and streams. δ15N of nitrate allowed direct identification of animal waste-produced nitrate in 11 of 14 wells sampled in this study, as well as recognition of nitrate contributions from non-animal waste agricultural sources in remaining wells.  相似文献   

3.
Eloctromigraiion offers a potential tool for remediating ground water contaminated with highly soluble components, such as Na+, Cl, NO3 and SO4−. A field experiment was designed to lest the efficacy of electromigration for preconcontrating dissolved SO42 in ground water associated with a fossil-fuel power plant. Two shallow wells, 25 feel apart (one 25 feel deep, the other 47 feet deep), were constructed in the upper portion of an unconfined alluvial aquifer. The wells were constructed with a double-wall design, with an outer casing of 4-inch PVC and an inner lube of 2-inch FVC; both were fully slotted (0.01 inch). Electrodes were constructed by wrapping the inner lulling with a 100-foot length of rare-earth metal oxide/copper wire. An electrical potential of 10.65 volts DC Was applied, and tests were run for periods of 12, 44, and 216 hours. Results showed large changes in the pH from the initial pH of ground water of about 7.5 to values of approximately 2 and 12 at the anode and cathode, respectively. Despite the fact that the test conditions were far from ideal, dissolved SO42-; was significantly concentrated at the anode. Over a period of approximately nine days, the concentration of SO42- at the anode reached what appeared to he a steady-state value of 2200 mg/L. compared lo the initial value in ground water of approximately 1150 mg/L. The results of this field lest should encourage further investigation of electromigration as a tool in the remediation of contaminated ground water.  相似文献   

4.
Recent nitrate, chloride, and bromide concentrations were studied in the Ogallala Aquifer of northwest Texas. The study included 361 wells with a median depth of 92 m in a rural area dominated by agricultural activity and oil and gas production. Only five observations surpassed the 44.3 mg/L standard for nitrate (10 mg/L NO3-N). Four other observations, and one from the preceding set, exceeded the secondary standard of 250 mg/L for chloride. Maximum concentrations were 91.2 mg/L, 1530 mg/L, and 0.70 mg/L for nitrate, chloride, and bromide, respectively. Chloride/bromide ratios covered a broad range, from 30.4 to 10930, but medians were < 160 for each of two years analyzed. There were statistically significant correlations between nitrate and chloride, and chloride and well depth. Results of this study suggest that agricultural activity has locally impacted ground water in north-west Texas. Regionally, low aquifer recharge rates have curtailed ground water contamination from potentially adverse land uses.  相似文献   

5.
Naotatsu  Shikazono 《Island Arc》1994,3(1):59-65
Abstract Chemical data on hydrothermally altered volcanic rocks from a green tuff belt in Japan indicate that the average rate of Mg removal from seawater due to seawater cycling through back-arc basins in the circum-Pacific region during the early to middle Miocene (25–15 Ma) is estimated to be 2.6±1 × 1013 g/year. This is similar to that through present-day mid-ocean ridges (2.4 × 1013 g/year). Hydrothermal fluxes of K, Ca and Si are calculated to be 4.2±1.6 × 1013 g/year, 4.3±1.7×1013 g/year and 1.0±0.4 × 1014 g/year, respectively. These calculated results indicate that the seawater/volcanic rocks interaction at subduction-related tectonic settings have to be taken into account in considering the geochemical mass balance of seawater over geologic time.  相似文献   

6.
To investigate the effect of sediment contamination on the tellinid bivalve Macomona liliana, juvenile shellfish (about 1.3 mm long) were exposed to copper- and zinc-dosed sand, and sediments collected from several contaminated sites. The behavioural responses measured included burial rate, crawling and drifting. In copper-dosed sediment, a significant reduction in the number of shellfish burying after 10 min occurred at 25 mg Cu kg−1 (dry wt). After a 96-h exposure, shellfish crawled away from sediment with 10 mg Cu kg−1 (dry wt), and when a weak current was provided they left this 10 mg Cu kg−1 (dry wt) sediment by drifting. Zinc-dosed sediment slowed burial at 80 mg Zn kg−1 (dry wt), and stimulated crawling and drifting at 40 mg Zn kg−1 (dry wt). Some of the field-collected contaminated sediments slowed burial and stimulated drifting, but none affected crawling. It appears that juvenile drifting induced by sediment contamination could play a role in determining M. liliana distributions.  相似文献   

7.
The formation and development of a salt plume (salinity up to 800 mg Cl 1−1) in the inner part of the Coastal Plain aquifer of Israel is analyzed. Massive groundwater exploitation during the 1950s caused a large drop in the water level and formation of a hydrologic depression in the Be'er Toviyya-Kefar Warburg area. The depression reached a maximal depth during the late 1960s; thereafter a reduction in the rate of pumpage led to restoration of water levels and shallowing of the depression, until its complete disappearance towards the end of the 1980s. A spot of high salinity first appeared in 1956, following a deep drawdown in the water levels. This saline plume has been continuously expanding with increasing salinity concentrations (200–800 mg Cl 1−1) in its center. The average rate of radial expansion was about 50 m year−1. The expansion and salinization did not cease as the depression disappeared. Rather, equalization of water levels in wells situated within the plume area with those of situated along its margins resulted in the salinization of the latter within a period of 1 year.

Mass balances for water and chloride contents were made for the period 1967–1990. Taking into consideration the storage change, pumpage, natural replenishment and artificial recharge, the lateral inflow to the depression is estimated as 60 × 106 m3. Upon addition of the chloride balance, and taking into consideration the chloride concentrations of the surrounding fresh water and the apparent possible end-member of the saline source (based on geochemical considerations), the saline inflow is estimated as (40–60) × 106 m3. These estimates indicate that a large amount of saline water penetrated into the aquifer, of about half of the natural replenishment of the study area, with an estimated salinity of 1900–2700 mg Cl 1−1.

It is suggested that the salt plume was formed as a result of a drop in water level combined with a flow of underlying saline water bodies from deeper strata. The chemical composition of the groundwater points to the existence of two saline water bodies of Ca-chloride composition and a marine Br/Cl ratio: (1) saline water with low Na/Cl (0.6), So4/Cl, and B/Cl ratio; (2) saline water with higher Na/Cl (> 0.6), So4/Cl, and B/Cl ratios. These chemical compositions resemble Ca-chloride saline waters found in other locations in the Coastal Plain aquifer and in underlying formations. The saline water bodies may occur in either pockets at the bottom of the aquifer or lumachelle and sandstone layers of high hydraulic conductivity in underlying sediments.  相似文献   


8.
Abstract Elemental and isotopic compositions of noble gases extracted from the bore hole water in Osaka plain, central Japan were examined. The water samples were collected from four shallow bore holes (180-450 m) and seven deep bore holes (600-1370 m) which have been used for an urban resort hot spring zone. The water temperatures of the deep bore holes were 22-50°C and that of the shallow bore holes, 13-23°C. The elemental abundance patterns show the progressive enrichment of the heavier noble gases compared with the atmospheric noble gas composition except for He, which is heavily enriched in deep bore hole water samples. 3He/4He ratios from the bore holes reaching the Ryoke granitic basement were higher than the atmospheric value (1.4 × 10−6), indicating a release of mantle He through the basement. The highest value of 8.2 × 10−6 is in the range of arc volcanism. On the other hand, the bore holes in sedimentary rocks overlying the basement release He enriched in radiogenic 4He, resulted in a low 3He/4He ratio of 0.5 × 10−6. 4He/20Ne and 40Ar/36Ar ratios indicate that the air contamination is generally larger in shallow bore holes than in deep ones from each site. The helium enriched in mantle He is compatible with the previous work which suggested up-rising magma in 'Kinki Spot', the area of Osaka and western Wakayama, in spite of no volcanic activity in the area. A model to explain an initiation of magma generation beneath this area is presented.  相似文献   

9.
Kelly WR 《Ground water》2008,46(5):772-781
The rapid expansion of major cities throughout the world is resulting in the degradation of water quality in local aquifers. Increased use of road deicers since the middle of the 20th century in cities in the northern United States, Canada, and Europe has been linked to degraded ground water quality. In this article, Chicago, Illinois, and its outlying suburban areas are used as an example of the effects of urbanization in a historical context. A statistical study of historical water quality data was undertaken to determine how urbanization activities have affected shallow (<60 m) ground water quality. Chloride (Cl−) concentrations have been increasing, particularly in counties west and south of Chicago. In the majority of shallow public supply wells in the western and southern counties, Cl− concentrations have been increasing since the 1960s. About 43% of the wells in these counties have rate increases greater than 1 mg/L/year, and 15% have increases greater than 4 mg/L/year. Approximately 24% of the samples collected from public supply wells in the Chicago area in the 1990s had Cl− concentrations greater than 100 mg/L (35% in the western and southern counties); median values were less than 10 mg/L before 1960. The greater increase in Cl− concentrations in the outer counties is most likely due to both natural and anthropogenic factors, including the presence of more significant and shallower sand and gravel deposits, less curbing of major highways and streets, and less development in some parts of these counties.  相似文献   

10.
A 5-year-old wood particle reactor treating agricultural tile drainage in southern Ontario was monitored for its ongoing ability to treat both nitrate (NO3–) and perchlorate (ClO4–). Prior to sampling undertaken in the fifth year of operation, a highway safety flare containing ClO4– was immersed in the inlet pipe elevating influent ClO4– concentrations to up to 33.7 μg/L. ClO4– removal rates were inhibited in the presence of more than 1 to 2 mg/L NO3–-N, but increased rapidly to about 60 μg/L/d upon NO3– depletion. Nitrate removal rates, measured subsequently in the sixth and seventh years of operation, varied with temperature in the range of 2 to 16 mg N/L/d, but remained similar to rates measured in the second year. Additionally, no deterioration in the hydraulic conductivity (K) of the coarse core layer (0.5 3– removal rates and can remain highly permeable over a number of years. The media can also provide high removal rates for other redox sensitive contaminants such as ClO4–. The ability to directly measure the reactor flow rate, in this case via an outlet pipe, greatly simplified the task of estimating hydraulic properties and reaction rates.  相似文献   

11.
Soil-solution samplers and shallow ground water monitoring wells were utilized to monitor nitrate movement to ground water following H2O2 application to a clogged soil absorption system. Nitrate-nitrogen concentrations in soil water and shallow ground water ranged from 29 to 67 mg/L and 9 to 22 mg/L, respectively, prior to H2O2 treatment. Mean nitrate-nitrogen concentrations in soil water and ground water increased and ranged from 67 to 115 mg/L and 23 to 37 mg/L, respectively, one week after H2O2 application. Elevated concentrations of nitrate-nitrogen above background persisted for several weeks following H2O2 treatment. The H2O2 treatment was unsuccessful in restoring the infiltrative capacity of a well-structured soil. Application of H2O2 to the soil absorption system poses a threat of nitrate contamination of ground water and its usefulness should be fully evaluated before rehabilitation is attempted.  相似文献   

12.
Abstract Self-potential variations were measured to estimate the magnitude of electrokinetic and hydrological parameters (zeta potential and permeability) of the Nojima Fault zone in Awaji, Japan. The study observed self-potential variations that seemed to be associated with water flow from the injection well to the fracture zone, which were induced by turning the injection on and off. Amplitudes of the variations were a few to 0.03 V across 320–450 m dipoles. These variations can be explained well with an electrokinetic model. The quantity k/ζ (permeability/zeta potential) is in the range 1.6 × 10−13− 5.4 × 10−13 m2/V. Permeability of the Nojima fault zone can be estimated as approximately 10−16–10−15 m2 on the assumption that the zeta potential is in the range –0.01 to –0.001 V.  相似文献   

13.
Machida I  Lee SH 《Ground water》2008,46(4):532-537
We observed long-term changes in the concentrations of dissolved ions in ground water caused by leachate from new volcanic ejecta deposited on the ground surface of the volcanic Miyakejima Island, Japan. Water samples were collected from nine wells and two rain collectors over a period of more than 10 years, and samples of runoff water were collected periodically. The samples were analyzed for temperature, pH, alkalinity, Cl−, and SO42−; some of the samples were also analyzed for δ13C. Because the leachate from the volcanic ejecta contained sulfate, we recorded an increase in SO42− concentrations in the (unconfined) well water. The increase in SO42− was initially detected between less than 1.4 and 5.2 years after the eruption, showing peak concentrations from 2.4 to 6.4 years after the eruption. This delayed response reflects the transit time of downward-moving SO42− in the vadose zone, corresponding to an apparent movement rate of 0.4 to 7.2 cm/d. The rate relates to the mean recharge, represented as a fraction of local mean rainfall, and is calculated using the Cl− balance method. The magnitude of the recorded increases reflects the volume of volcanic mudflow on the ground surface within the basin. For the management of ground water after an eruption, it is therefore important to know the chemical properties of the volcanic ejecta and the spatial distribution of mudflow to estimate the magnitude of the effect of ejecta on ground water quality.  相似文献   

14.
To assess the vulnerability of ground water to contamination in the karstic Upper Floridan aquifer (UFA), age-dating tracers and selected anthropogenic and naturally occurring compounds were analyzed in multiple water samples from a public supply well (PSW) near Tampa, Florida. Samples also were collected from 28 monitoring wells in the UFA and the overlying surficial aquifer system (SAS) and intermediate confining unit located within the contributing recharge area to the PSW. Age tracer and geochemical data from the earlier stage of the study (2003 through 2005) were combined with new data (2006) on concentrations of sulfur hexafluoride (SF6), tritium (3H), and helium-3, which were consistent with binary mixtures of water for the PSW dominated by young water (less than 7 years). Water samples from the SAS also indicated mostly young water (less than 7 years); however, most water samples from monitoring wells in the UFA had lower SF6 and 3H concentrations than the PSW and SAS, indicating mixtures containing high proportions of older water (more than 60 years). Vulnerability of the PSW to contamination was indicated by predominantly young water and elevated nitrate-N and volatile organic compound concentrations that were similar to those in the SAS. Elevated arsenic (As) concentrations (3 to 19 μg/L) and higher As(V)/As(III) ratios in the PSW than in water from UFA monitoring wells indicate that oxic water from the SAS likely mobilizes As from pyrite in the UFA matrix. Young water found in the PSW also was present in UFA monitoring wells that tap a highly transmissive zone (43- to 53-m depth) in the UFA.  相似文献   

15.
Abstract A loam section near Daisen volcano, South-west Japan, has been examined for low-field magnetic susceptibility (MS) and fine quartz accumulation rate. Fission track dating of tephra layers interbedded in the deposit shows that the loam age ranges from about 200 ka to the Present. The MS was measured for both bulk sample and the < 63 μm fine fraction. Fine quartz contents in the < 63 μm fraction were also determined using acid-alkali digestions and recalculated to derive fine quartz accumulation rate (Rqz). Grain size analysis was then carried out on the separated fine quartz. Low-field MS varies from low frequency magnetic suspectibility (χ(LF)) 5 to 100 (× 10−6 m3/kg) for bulk samples and from 1 to 30 for fine fractions. The fine fraction χ(LF) variation correlated with Chinese loess MS stratigraphy, which indicated changes in pedogenic enhancement of the MS and is reflected by summer monsoon intensity. The Rqz are high in cool climate stages, with volumes between 0.2 and 0.4 (× 10−2 kg/m2 per yr), whereas in warm stages the rate falls to about 0.1. These values compare well with those reported from the Hokkaido and Kanto areas, suggesting the fine quartz originates from tropospheric dust. The strong winter monsoons during glacial stages alternated with weak summer monsoons as a result of a southward shift of the jet stream. In interglacials, summer monsoons were stronger. Seasonal alternating monsoons appear to have operated in South-west Japan through the past 200 000 years.  相似文献   

16.
Hydraulic conductivity values computed using the steady-state discharge and drawdown attained while low-flow sampling were evaluated to determine if they were equivalent to those determined from slug testing. Based on testing 12 wells, it was found that the results were statistically equivalent. Conductivity values computed using low-flow sampling parameters were also evaluated as to their reproducibility in actual practice by analyzing consultant data for three wells sampled over three quarterly monitoring periods by four field technicians. The results were found to be reproducible within about a factor of 2 or better. Since the method is based on only one pair of parameters, diligence is required in attaining steady state and in accurately measuring the flow rate and drawdown. Conductivity values computed using this approach can enhance the use of low-flow data gathered in water quality sampling, avoid the need for slug testing in a subsequent phase of investigation, and help reduce the cost of characterizing sites when multilevel samplers are used. Given the practical range of discharge in low-flow sampling, the method was found to be applicable at conductivity values somewhat greater than 10−6 cm/s. Given the typical accuracy of water level meters and pressure transducers and a maximum discharge of 1 L/min, as mandated by regulatory guidance, the method has a calculated upper conductivity limit in the range of 10−3 to 10−2 cm/s.  相似文献   

17.
Studies have shown that materials, such us polytetra-fluoroethylene (PTFE), rigid polyvinyl chloride (rigid PVC). flexible polyvinyl chloride (flexible PVC), stainless steel (SS). low-density polyethylene (LDPE), and high-density polyethylene (HDPE), have the potential to influence certain analyte concentrations in ground water samples. The effects of HDPE, LDPE, PTFE, rigid PVC, and SS on aqueous concentrations of nitrate-N, atrazine, deethylatrazine (DEA), and deisopropylatrazine (DIA) were evaluated in a field study A laboratory study was conducted to evaluate sorption of atrazine DEA, DIA, cyanazine, alachlor, metolachlor, and butachlor to PTFE, HDPE, and SS materials. Butachlor is rarely use in the United States, but was included because of its expected high sorptivity. No significant differences between HDPE, LDPE, PTFE, rigid PVC, and SS were determined for any of the analytes tested in the field study. In the laboratory study, sorption of DIA to PTFE and SS was significant at 2.6 × 10−5 and 4.1 × 10−5μg/m2 respectively. Sorption of DIAA to HDPE was not significantly > 0 sorption of all other compounds to HDPE, PTFE, and SS were also not significantly >0. Results of the two studies indicate that for these analytes (relatively polar or ionized compounds), representative ground water samples are not dependent on the materials used for multilevel sampler construction. When considering these compounds, it appears that the least expensive materials (HDPE, rigid PVC, and LDPE) are good choices for the construction of ground water monitoring wells.  相似文献   

18.
A large number of ground water samples (360) was collected from 60 stations over six consecutive seasons to study the influence of the main sewerage drain on shallow ground water table beneath the municipal area of Cuttack, India. A majority of the samples collected from stations close to the drain exceeded the maximum permissible limits set by the World Health Organization (WHO). Almost all the samples near the drain exceeded the WHO limit for NO3- and Na+. However, the concentrations decreased as the distance from the drain increased. The winter season registered the maximum concentrations of NH4+, NO3-, and SO42- ions whereas the minimum values always coincided with the rainy season. R-mode factor analysis was conducted to find relationships amongst the 16 chemical parameters studied. Fluoride showed a negative correlation with Cl-, Na+, NO3-, SO42-, and PO43-. The concentration of F- may be lower in raw waste water than naturally occurs in the ground water. Therefore, a decrease in the concentration of F- near the drain may be attributed to dilution by contributions of waste water to the ground water. The rest of the parameters were found to be directly related to the distance of collection points to the sewerage. The distribution of nutrients is strongly affected by leaching of waste water into the ground water.  相似文献   

19.
While the existence of relatively fresh groundwater sequestered within permeable, porous sediments beneath the Atlantic continental shelf of North and South America has been known for some time, these waters have never been assessed as a potential resource. This fresh water was likely emplaced during Pleistocene sea-level low stands when the shelf was exposed to meteoric recharge and by elevated recharge in areas overrun by the Laurentide ice sheet at high latitudes. To test this hypothesis, we present results from a high-resolution paleohydrologic model of groundwater flow, heat and solute transport, ice sheet loading, and sea level fluctuations for the continental shelf from New Jersey to Maine over the last 2 million years. Our analysis suggests that the presence of fresh to brackish water within shallow Miocene sands more than 100 km offshore of New Jersey was facilitated by discharge of submarine springs along Baltimore and Hudson Canyons where these shallow aquifers crop out. Recharge rates four times modern levels were computed for portions of New England's continental shelf that were overrun by the Laurentide ice sheet during the last glacial maximum. We estimate the volume of emplaced Pleistocene continental shelf fresh water (less than 1 ppt) to be 1300 km3 in New England. We also present estimates of continental shelf fresh water resources for the U.S. Atlantic eastern seaboard (104 km3) and passive margins globally (3 × 105 km3). The simulation results support the hypothesis that offshore fresh water is a potentially valuable, albeit nonrenewable resource for coastal megacities faced with growing water shortages.  相似文献   

20.
Geographical distribution of helium isotope ratios in northeastern Japan   总被引：1，自引：0，他引：1  
Keika  Horiguchi  Sadato  Ueki  Yuji  Sano  Naoto  Takahata  Akira  Hasegawa  George  Igarashi 《Island Arc》2010,19(1):60-70
In order to study the precise geographical distribution of helium isotope ratios in northeastern Japan and compare it with geophysical data, we collected 43 gas and water samples from hot and mineral springs in the region where the ratio had never been reported, and measured the 3He/4He and 4He/20Ne ratios of these samples. It was found that the 3He/4He ratios show clear contrasts between the forearc and the back-arc regions in the Tohoku district in northeastern Japan. In the forearc region, the ratios are smaller than 1 RA (1 RA = 1.4 × 10−6; RA means the 3He/4He ratio of the atmosphere). On the other hand, those along the volcanic front and in the back-arc region are apparently higher. Moreover, we found a variation in the 3He/4He ratios along the volcanic front. In Miyagi Prefecture (38–39°N), the ratios range from 2 to 5 RA. On the other hand, the ratios are less than 1 RA in and around the southern border between Iwate and Akita Prefectures (39–39.5°N). Comparing the distribution of helium isotope ratios to results of recent geophysical studies, we found that the features in geographical distribution of helium isotope ratios are similar to those of seismic low-velocity zone distributions and high Qp−1 distributions in the uppermost mantle. These observations strongly suggest that the helium isotope ratios reflect the distribution of melts in the uppermost mantle and are a useful tool for investigating the origin, behavior, and distribution of deep fluids and melts.  相似文献   

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