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1.
Tomohiro  Toki  Toshitaka  Gamo  Urumu  Tsunogai 《Island Arc》2006,15(3):285-291
Abstract   We collected free-gas and in situ fluid samples up to a depth of 200.6 m from the Sagara oil field, central Japan (34°44'N, 138°15'E), during the Sagara Drilling Program (SDP) and measured the concentrations and stable carbon isotopic compositions of CH4 and C2H6 in the samples. A combination of the CH4/C2H6 ratios with the carbon isotope ratios of methane indicates that the hydrocarbon gases are predominantly of thermogenic origin at all depths. The isotope signature of hydrocarbon gases of δ13      < δ13     suggests that these gases in the Sagara oil field are not generated by polymerization, but by the decomposition of organic materials.  相似文献   

2.
Susumu  Kato  Amane  Waseda  Hideki  Nishita 《Island Arc》2006,15(3):304-312
Abstract   Six oil samples collected from the Sagara oil field, Shizuoka Prefecture, were geochemically analyzed. Unlike the Niigata oils, the Sagara oils: (i) are low-sulphur light oils dominated by gasoline and kerosene fractions; (ii) have low values of environment index in light hydrocarbon compositions; (iii) have high Pr/ n -C17 and low Ph/ n -C18 ratios and high oleanane/hopane ratios; (iv) have high relative abundance of C29 and low relative abundance of C28 regular steranes; and (v) have 'light' stable carbon isotope compositions. These characteristics show that the source rocks of the Sagara oils contain mainly marine organic matter, but with more input of terrigenous organic matter deposited under more oxic conditions compared to those of the Niigata oils. The light carbon isotope compositions and the low relative abundance of C28 regular steranes of the Sagara oils suggest that their source rock is not Miocene, but probably Paleogene in age. The Sagara oils probably migrated along faults from deeper parts of the basin.  相似文献   

3.
Water samples collected for the determination of volatile organic compounds (VOCs) are often preserved with hydrochloric acid (HCl) to inhibit the biotransformation of the analytes of interest until the chemical analyses can he performed. However, it is theoretically possible that residual free chlorine in the HCl can react with dissolved organic carbon (DOC) to form chloroform via the haloform reaction. Analyses of 1501 ground water samples preserved with HCl from the U.S. Geological Survey's National Water-Quality Assessment Program indicate that chloroform was the most commonly detected VOC among 60 VOCs monitored. The DOC concentrations were not significantly larger in samples with detectable chloroform than in those with no delectable chloroform, nor was there any correlation between the concentrations of chloroform and DOC. Furthermore, chloroform was detected more frequently in shallow ground water in urban areas (28.5% of the wells sampled) than in agricultural areas (1.6% of the wells sampled), which indicates that its detection was more related to urban land-use activities than to sample acidification. These data provide strong evidence that acidification with HCl does not lead to the production of significant amounts of chloroform in ground water samples. To verify these results, an acidification study was designed to measure the concentrations of all trihalomethanes (THMs) that can form as a result of HCl preservation in ground water samples and to determine if ascorbic acid (C6H8O6) could inhibit this reaction if it did occur. This study showed that no THMs were formed as a result of HCl acidification, and that ascorbic acid had no discernible effect on the concentrations of THMs measured.  相似文献   

4.
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   

5.
Hydrogen gas was discovered within the steel casing above standing water in a percussion-drilled borehole on the Hanlord Site in south-central Washington state. In situ measurements of the borehole fluids indicated anoxic, low-Eh (<-400 mV) conditions. Ground water sampled from adjacent wells in the same formation indicated that the ground water was oxygenated. H2 was generated during percussion drilling, due to the decomposition of borehole waters as a result of aqueous reactions with drilled sediment and steel from the drilling tools or casing. The generation of H2 within percussion-drilled boreholes that extend below the water table may be more common than previously realized. The ambient concentration of H2 produced during drilling was limited by microbial activity within the casing-resident fluids. H2 was generated abiotically in the laboratory, whereby sterilized borehole slurry samples produced 100 times more H2 than unsterilizcd samples. It appears that H2 is metabolized by microorganisms and concentrations might be significantly greater if not for microbial metabolism.  相似文献   

6.
Electromigration is proposed as an in situ method for preconcentrating contaminants in ground water prior to pumping and treating. In earlier investigations by the senior author and co-workers, it was found that Cu in synthetic ground water migrated strongly to a Pt cathode and plated out as metallic copper. In the present study, carbon electrodes were inserted into a laboratory column of fine quartz sand that was saturated with a lower concentration of CuSO4 solution. A fixed potential of 2.5 V was applied, causing dissolved Cu and SO4 to accumulate strongly at the cathode and anode, respectively. Only minor plating-out of Cu took place on the carbon electrodes. In addition to the use of carbon electrodes, the present research also investigated the effects of a lower concentration of metal, accumulation of SO4 adjacent to the anodes, adsorption of Cu on the sand, and competition by moving ground water.
At an imposed voltage of 2.5 V and in the presence of 65 mg/L of dissolved Cu and 96 mg/L of SO4 (0.001 M CuSO4 solution), electrolysis of water caused large changes in the pH and speciation of the aqueous components, as well as precipitation of solid Cu-hydroxides. Significant retardation of Cu occurred in the presence of ground water flowing at an average intergranular velocity of 0.2 m/day, but only minor retardation at water velocities of 1.9 and 2.9 m/day.
Sulfate tends to migrate strongly to the anodes, suggesting that in situ electromigration may offer a useful new method for preconcentrating such highly soluble ions as SO4, NO3, and CI that are difficult to remove by conventional pump-and-treat methods. A number of potential problems exist that should be addressed in a field test.  相似文献   

7.
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   

8.
A biological community was discovered in the Northern Okushiri Ridge, northeastern Japan Sea. The community was closely associated with sea-floor fissures, and presumed to be supported by methanotrophic and/or thiotrophic bacterial production. Sediments inside of and in the vicinity of the fissures were collected, and the short-chain (C9–20) sediment fatty acids were analyzed for amounts and compositions. The fatty acid compositions were compared with those from a known methane seep and a submarine volcano in the Sagami Bay, central Japan, and from a whale skeleton at the Torishima Seamount, northwestern Pacific Ocean. As a result, a close relationship between the sediments from the Northern Okushiri Ridge, the known methane-seep, and the whale skeleton was found. This finding represents the first discovery of methane seepage and associated biological communities in the Japan Sea. This also supports the hypothesis that the eastern margin of the northern Japan Sea is at the early stage of new subduction.  相似文献   

9.
Sharma S  Frost CD 《Ground water》2008,46(2):329-334
Recovery of hydrocarbons commonly is associated with coproduction of water. This water may be put to beneficial use or may be reinjected into subsurface aquifers. In either case, it would be helpful to establish a fingerprint for that coproduced water so that it may be tracked following discharge on the surface or reintroduction to geologic reservoirs. This study explores the potential of using δ13C of dissolved inorganic carbon (DIC) of coalbed natural gas (CBNG)–coproduced water as a fingerprint of its origin and to trace its fate once it is disposed on the surface. Our initial results for water samples coproduced with CBNG from the Powder River Basin show that this water has strongly positive δ13CDIC (12‰ to 22‰) that is readily distinguished from the negative δ13C of most surface and ground water (−8‰ to −11‰). Furthermore, the DIC concentrations in coproduced water samples are also high (more than 100 mg C/L) compared to the 20 to 50 mg C/L in ambient surface and ground water of the region. The distinctively high δ13C and DIC concentrations allow us to identify surface and ground water that have incorporated CBNG-coproduced water. Accordingly, we suggest that the δ13CDIC and DIC concentrations of water can be used for long-term monitoring of infiltration of CBNG-coproduced water into ground water and streams. Our results also show that the δ13CDIC of CBNG-coproduced water from two different coal zones are distinct leading to the possibility of using δ13CDIC to distinguish water produced from different coal zones.  相似文献   

10.
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   

11.
Hidehisa  Mashima 《Island Arc》2005,14(2):165-177
Abstract   The major element and compatible trace element compositions of the northwest Kyushu basalts (NWKBs) collected from Saga-Futagoyama were analyzed to examine the petrogenesis of these basalts. Although nepheline-normative alkaline basalts are not found in the basalts from Saga-Futagoyama, the Saga-Futagoyama basalts almost cover the major element variations of NWKBs. The basalts can be chemically divided into two groups: an Fe-poor group (IPG) and an Fe-rich group (IRG). The compositional variation of IPG basalts is essentially controlled by the partial melting of the source as suggested by the following: (i) bulk rock MgO, FeO and NiO compositions indicate that some IPG samples were equilibrated with mantle olivine; and (ii) correlations between Al2O3, CaO and MgO are consistent with those of experimental partial melts of peridotites. The inconsistent behaviors of the elements compatible with clinopyroxene (Cpx), such as V (Sc and Cu), preclude the significant role of the fractional crystallization of Cpx and spinel in IPG variation. IPG basalts have low Al and high Fe concentrations compared to the products of melting experiments involving peridotites and pyroxenites, suggesting that the IPG source would have a lithology and bulk rock composition different from those of typical peridotites and pyroxenites. IRG basalts have negative correlations between Fe2O3* and MgO, and between V and Fe2O3*/MgO, indicating that IRG basalts would have fractionated Cpx. However, the anomalously Fe-rich feature of IRG basalts compared with NWKBs collected from other areas suggests that the role of Cpx fractionation in NWKBs is minor. Relatively low melting temperatures would have principally caused the large chemical variation of NWKBs.  相似文献   

12.
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   

13.
Pumped waters from 14 Pennsylvania wells, located in shallow sandstone, siltstone and shale aquifers, were continuously monitored for dissolved oxygen (D. O.), nitrate (NO3), pH, electrical conductivity (EC) and water temperature in a discharge manifold at the well head. The amount of pumping or purging required to stabilize these parameter readings varied by well site and parameter being analyzed. However, the purging required was generally greatest for D. O. and least for water temperature where: D. O. < NO3 pH < EC < water temperature. Wells located near the siltstone-shale interface generally required far more purging than did wells located elsewhere. Although parameter stability was often achieved within purging one bore volume, the complexity, diversity, and variability in the data and these well-ground water systems, suggest that no single purging rule is appropriate. Instead, the extent of purging required before sampling these shallow aquifers should be determined by incorporating on-site monitoring of target or related parameters into the purging process.
From a sampling perspective, the relationship between NO3 and D. O. concentrations during purging were analyzed relative to aquifer type. For most wells located in sandstone or siltstone, NO3 concentrations remained relatively constant during purging irrespective of changes in D. O. For most wells located in shale, these two were positively and similarly correlated, suggesting that a general relationship exists.  相似文献   

14.
Abstract Dolomite marble from the Kumdy–Kol area of the Kokchetav Massif contains abundant microdiamond, mainly in garnet and a few in diopside. The mineral assemblage at peak metamorphic condition consists of dolomite + diopside + garnet (+ aragonite) ± diamond. Inclusions of very low MgCO3 calcite and almost pure calcite occur in diopside and are interpreted as aragonite and/or aragonite + dolomite. Single-phase Mg–calcite in diopside with a very high MgCO3 component (up to 21.7 mol%) was also found in diamond-free dolomitic marble, and is interpreted as a retrograde product from aragonite + dolomite to Mg–calcite. The dolomite stability constrains the maximum pressure (P) at < 7 GPa using previous experimental data, whereas the occurrence of diamond yields the minimum peak pressure–temperature (P–T) condition at 4.2 GPa and 980 °C at X co 2 = 0.1. The highest MgCO3 in Mg–calcite constrains the minimum P–T condition higher than 2.5 GPa and 800 °C for the exhumation stage. As these marbles were subjected to nearly identical P–T metamorphic conditions, the appearance of diamond in some carbonate rocks was explained by high X co 2. A low X co 2 condition refers to high oxidized conditions and diamond (and/or graphite) becomes unstable. Difference in X co 2 for marble from the same area suggests local heterogeneity of fluid compositions during ultrahigh-pressure metamorphism.  相似文献   

15.
A six year field experiment has shown that a sand-bentonite mixture used to seal monitoring wells in aquitards contributes solutes to the ground water sampled from these wells. Monitoring wells were installed at field sites with hydraulic conductivity (K) ranging from 5 × 10 -9 m/s to 3 × 1011 m/s. In most cases the boreholes remained dry during installation which allowed the placement of a dry powdered bentonite/sand mixture tagged with potassium bromide (KBr) to seal and separate sampling points. Over six years, wells were sampled periodically and ground-water samples were analyzed for Br and Cl and other major ions. Typical Br results ranged from 10 mg/1 to 35 mg/1 in the first 700 days, as compared to an estimated initial concentration in the seal material of about 75 mg/1. After six years the bromide concentrations had decreased to between 3 mg/1 and 5 mg/1. The total mass of Br removed in six years is less than 50% of that placed; therefore the contamination effects, although considerably diminished, persist. The trends of Br, Cl, Na, and SO4 indicate that varying degrees of contamination occur. These data show that the materials used to seal monitoring wells in aquitards can have a significant and long-lasting impact on the chemistry of the water in the wells.  相似文献   

16.
The goal of this study was the cleanup of residual solvents in the saturated zone using an in situ biochemical treatment. Perchloroethylene (PCE) was chosen as a model compound because it is the most commonly found organic ground water contaminant. A mixture of vitamin B12 with titanium citrate was pumped as the remedial solution through a column containing 100 μL of PCE residual. The rate of reaction was found to be first order with respect 10 the concentration of PCE and to the concentration of vitamin B2. At 10 ppm B12, more than 85 percent PCM was degraded to trichloroelhylene (TCE) and dichloroelhylene (DCE) in two hours. The presence of low to moderate concentrations of organic carbon had no significant effect on the reaction. Vitamin B12 reduced by titanium citrate was found lo be compatible with the survival of anaerobic bacteria. The four major advantages of the biochemical system over the use of anaerobic bacteria are that (1) the rate is faster: (2) there is no need for the careful balance of nutrients or the addition of an extraneous carbon source: (3) there is no restriction in the concentration range of the compound to be treated; and (4) the remedial solution is mobile, even in the presence of organic carbon.  相似文献   

17.
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   

18.
Groundwater contamination by fuel-related compounds such as the fuel oxygenates methyl tert -butyl ether (MTBE), tert -butyl alcohol (TBA), and tert -amyl methyl ether (TAME) presents a significant issue to managers and consumers of groundwater and surface water that receives groundwater discharge. Four sites were investigated on Long Island, New York, characterized by groundwater contaminated with gasoline and fuel oxygenates that ultimately discharge to fresh, brackish, or saline surface water. For each site, contaminated groundwater discharge zones were delineated using pore water geochemistry data from 15 feet (4.5 m) beneath the bottom of the surface water body in the hyporheic zone and seepage-meter tests were conducted to measure discharge rates. These data when combined indicate that MTBE, TBA, and TAME concentrations in groundwater discharge in a 5-foot (1.5-m) thick section of the hyporheic zone were attenuated between 34% and 95%, in contrast to immeasurable attenuation in the shallow aquifer during contaminant transport between 0.1 and 1.5 miles (0.1 to 2.4 km). The attenuation observed in the hyporheic zone occurred primarily by physical processes such as mixing of groundwater and surface water. Biodegradation also occurred as confirmed in laboratory microcosms by the mineralization of U- 14C-MTBE and U-14C-TBA to 14CO2 and the novel biodegradation of U- 14C-TAME to 14CO2 under oxic and anoxic conditions. The implication of fuel oxygenate attenuation observed in diverse hyporheic zones suggests an assessment of the hyporheic zone attenuation potential (HZAP) merits inclusion as part of site assessment strategies associated with monitored or engineered attenuation.  相似文献   

19.
Sorption of dissolved Fe2+ on bentonite was studied using a batch technique. The distribution coefficient, Kd , was evaluated for a bentonite-iron system as a function of contact time, pH, sorbent and sorbate concentrations, and temperature. Sorption results were interpreted in terms of Freundlich's and Langmuir's equations. Thermodynamic parameters for the sorption system were determined at three temperatures: 298°, 308°, and 318°K. The values of ΔH°(-4.0 kjmol−1) and ΔG°(-2.46 Kjmol−1) at 298°K (25°C) suggest that sorption of iron on bentonite is an exothermic and a spontaneous process. The ΔG° value became less negative at higher temperatures and, therefore, less iron was sorbed at higher temperatures. The desorption studies with 0.01 M CaCl2 and deionized water at iron loading on bentonite showed that more than 90 wt% of the iron is irreversibly sorbed, probably due to the fixation of the iron by isomorphous replacement in the crystal lattice of the sorbent.  相似文献   

20.
Installation of a permeable reactive barrier to intercept a phosphate (PO4) plume where it discharges to a pond provided an opportunity to develop and test methods for monitoring the barrier's performance in the shallow pond-bottom sediments. The barrier is composed of zero-valent-iron mixed with the native sediments to a 0.6-m depth over a 1100-m2 area. Permanent suction, diffusion, and seepage samplers were installed to monitor PO4 and other chemical species along vertical transects through the barrier and horizontal transects below and near the top of the barrier. Analysis of pore water sampled at about 3-cm vertical intervals by using multilevel diffusion and suction samplers indicated steep decreases in PO4 concentrations in ground water flowing upward through the barrier. Samples from vertically aligned pairs of horizontal multiport suction samplers also indicated substantial decreases in PO4 concentrations and lateral shifts in the plume's discharge area as a result of varying pond stage. Measurements from Lee-style seepage meters indicated substantially decreased PO4 concentrations in discharging ground water in the treated area; temporal trends in water flux were related to pond stage. The advantages and limitations of each sampling device are described. Preliminary analysis of the first 2 years of data indicates that the barrier reduced PO4 flux by as much as 95%.  相似文献   

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