排序方式: 共有46条查询结果,搜索用时 182 毫秒
1.
2.
Sensitivity assessment of strontium isotope as indicator of polluted groundwater for hydraulic fracturing flowback fluids produced in the Dameigou Shale of Qaidam Basin 下载免费PDF全文
Hydrogeochemical processes that would occur in polluted groundwater and aquifer system, may reduce the sensitivity of Sr isotope being the indicator of hydraulic fracturing flowback fluids(HFFF) in groundwater. In this paper, the Dameigou shale gas field in the northern Qaidam Basin was taken as the study area, where the hydrogeochemical processes affecting Sr isotope was analysed. Then, the model for Sr isotope in HFFF-polluted groundwater was constructed to assess the sensitivity of Sr isotope as HFFF indicator. The results show that the dissolution can release little Sr to polluted groundwater and cannot affect the εSr(the deviation of the 87 Sr/86 Sr ratio) of polluted groundwater. In the meantime, cation exchange can considerably affect Sr composition in the polluted groundwater. The Sr with low εSr is constantly released to groundwater from the solid phase of aquifer media by cation exchange with pollution of Quaternary groundwater by the HFFF and it accounts for 4.6% and 11.0% of Sr in polluted groundwater when the HFFF flux reaches 10% and 30% of the polluted groundwater, respectively. However, the Sr from cation exchange has limited impact on Sr isotope in polluted groundwater. Addition of Sr from cation exchange would only cause a 0.2% and 1.2% decrease in εSr of the polluted groundwater when the HFFF flux reaches 10% and 30% of the polluted groundwater, respectively. These results demonstrate that hydrogeochemical processes have little effect on the sensitivity of Sr isotope being the HFFF indicator in groundwater of the study area. For the scenario of groundwater pollution by HFFF, when the HFFF accounts for 5%(in volume percentage) of the polluted groundwater, the HFFF can result in detectable shifts of εSr(ΔεSr=0.86) in natural groundwater. Therefore, after consideration of hydrogeochemical processes occurred in aquifer with input of the HFFF, Sr isotope is still a sensitive indicator of the Quaternary groundwater pollution by the HFFF produced in the Dameigou shale of Qaidam Basin. 相似文献
3.
本文在总结铀矿水分散体规模的基础上,对铀矿水文地球化学代矿工作的网度要求进行了讨论,提出区调阶段的工作比例尺为1:20万—1:10万,普查阶段为1:5万—1:2.5万,详查阶段为1:1万—1:5000;在阐明各工作阶段所圈定的水文地球化学场的地质含义的基础上,讨论了中、小比例尺水文地球化学调查工作的原理、效果及技术要求。提出了在潮湿多雨地区开展水分散流找矿的合理性和优越性。指出了水分散流找矿的关键是分析方法的灵敏度和精度。在水文地球化学调查中要注意通用找矿标志和矿化度(电导)的取样分析工作。 相似文献
4.
N. Janardhana Raju 《Environmental Geology》2007,52(6):1067-1074
In the management of water resources, quality of water is just as important as its quantity. In order to know the quality
and/or suitability of groundwater for domestic and irrigation in upper Gunjanaeru River basin, 51 water samples in post-monsoon
and 46 in pre-monsoon seasons were collected and analyzed for various parameters. Geological units are alluvium, shale and
quartzite. Based on the analytical results, chemical indices like percent sodium, sodium adsorption ratio, residual sodium
carbonate, permeability index (PI) and chloroalkaline indices were calculated. The pre-monsoon waters have low sodium hazard
as compared to post-monsoon season. Residual sodium carbonate values revealed that one sample is not suitable in both the
seasons for irrigation purposes due the occurrence of alkaline white patches and low permeability of the soil. PI values of
both seasons revealed that the ground waters are generally suitable for irrigation. The positive values of Chloroalkaline
indices in post-monsoon (80%) and in pre-monsoon (59%) water samples indicate absence of base-exchange reaction (chloroalkaline
disequilibrium), and remaining samples of negative values of the ratios indicate base-exchange reaction (chloroalkaline equilibrium).
Chadha rectangular diagram for geochemical classification and hydrochemical processes of groundwater for both seasons indicates
that most of waters are Ca–Mg–HCO3 type. Assessment of water samples from various methods indicated that majority of the water samples in both seasons are suitable
for different purposes except at Yanadipalle (sample no. 8) that requires precautionary measures. The overall quality of groundwater
in post-monsoon season in all chemical constituents is on the higher side due to dissolution of surface pollutants during
the infiltration and percolation of rainwater and at few places due to agricultural and domestic activities. 相似文献
5.
Pan Wu Changyuan Tang Congqiang Liu Lijun Zhu TingQuan Pei Lijuan Feng 《Environmental Geology》2009,57(7):1457-1467
The chemical characteristics, formation and natural attenuation of pollutants in the coal acid mine drainage (AMD) at Xingren
coalfield, Southwest China, are discussed in this paper based on the results of a geochemical investigation as well as geological
and hydrogeological background information. The chemical composition of the AMD is controlled by the dissolution of sulfide
minerals in the coal seam, the initial composition of the groundwater and the water–rock interaction. The AMD is characterized
by high sulfate concentrations, high levels of dissolved metals (Fe, Al, Mn, etc.) and low pH values. Ca2+ and SO4
2− are the dominant cation and anion in the AMD, respectively, while Ca2+ and HCO3
− are present at significant levels in background water and surface water after the drainage leaves the mine site. The pH and
alkalinity increase asymptotically with the distance along the flow path, while concentrations of sulfate, ferrous iron, aluminum
and manganese are typically controlled by the deposition of secondary minerals. Low concentrations of As and other pollutants
in the surface waters of the Xingren coalfield could be due to relatively low quantities being released from coal seams, to
adsorption and coprecipitation on secondary minerals in stream sediments, and to dilution by unpolluted surface recharge.
Although As is not the most serious water quality problem in the Xingren region at present, it is still a potential environmental
problem.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
6.
In the western part of the city of Zagreb, Croatia, hydrogeochemical and isotopic investigations of the Samobor aquifer were
carried out with the aim of determining the differences in hydrogeochemical characteristics at increasing aquifer depths.
The aquifer comprises 40-m thick gravelly–sandy deposits, with lenses and interlayers of silt and clay. The analyses have
proven that with increasing aquifer depth, there are decreases in groundwater temperature and the values of electrical conductivity
and increases in the sodium, iron and manganese concentrations. The δ13C distribution shows an evident increase in biogenic carbon concentrations with increasing aquifer depth. The measured specific
14C activities showed that the deeper part of the aquifer is characterized by slow water exchange, while the shallower part
is influenced by current recharge, although the pumping wells located on the well-field downstream penetrate the aquifer fully.
A direct exchange of water from the Sava River and groundwater occurs in the near vicinity of the river. This exchange weakens
further away, while the difference in hydrogeochemical characteristics between the Sava River water and groundwater increases. 相似文献
7.
8.
Salinity mapping of coastal groundwater aquifers using hydrogeochemical and geophysical methods: a case study from north Kelantan,Malaysia 总被引:2,自引:0,他引:2
Integrated hydrogeochemical and geophysical methods were used to study the salinity of groundwater aquifers along the coastal
area of north Kelantan. For the hydrogeochemical investigation, analysis of major ion contents of the groundwater was conducted,
and other chemical parameters such as pH and total dissolved solids were also determined. For the geophysical study, both
geoelectrical resistivity soundings and reflection seismic surveys were conducted to determine the characteristics of the
subsurface and groundwater contained within the aquifers. The pH values range from 6.2 to 6.8, indicating that the groundwater
in the study area is slightly acidic. Low content of chloride suggests that the groundwater in the first aquifer is fresh,
with an average concentration of about 15.8 mg/l and high geoelectrical resistivity (>45 ohm m). On the other hand, the groundwater
in the second aquifer is brackish, with chloride concentration ranging from 500 mg/l to 3,600 mg/l and very low geoelectrical
resistivity (<45 ohm m) as well as high concentration of total dissolved solids (>1,000 mg/l). The groundwater in the third
aquifer is fresh, with chloride concentrations generally ranging from 2 mg/l to 210 mg/l and geoelectrical resistivity of
greater than 45 ohm m. Fresh and saltwater interface in the first aquifer is generally located directly in the area of the
coast, but, for the second aquifer, both hydrogeochemical and geoelectrical resistivity results indicate that the fresh water
and saltwater interface is located as far as 6 km from the beach. The considerable chloride ion content initially suggests
that the salinity of the groundwater in the second aquifer is probably caused by the intrusion of seawater. However, continuous
monitoring of the chloride content of the second aquifer indicated no significant changes with time, from which it can be
inferred that the salinity of the groundwater is not affected by seasonal seawater intrusion. Schoeller diagrams illustrate
that sulphate concentrations of the groundwater of the second aquifer are relatively low compared to those of the recent seawater.
Therefore, this result suggests that the brackish water in the second aquifer is probably from ancient seawater that was trapped
within the sediments for a long period of time, rather than due to direct seawater intrusion. 相似文献
9.
Major and trace elements in groundwater from basaltic aquifers in pristine conditions were investigated in a volcanic island to evaluate sources, sinks, and mobility of elements over a wide range of mineralization conditions with total dissolved solids from 50 mg/L to 3400 mg/L. Groundwater was highly undersaturated with respect to primary silicate minerals, indicating that dissolution of basaltic rocks may continue under conditions with precipitation of calcite and secondary silicates. Evolution of B/Cl ratio in groundwater from marine aerosols to basaltic rocks showed that the ratio could be used as a conservative tracer for interactions between water and basaltic rocks. Relative mobility (RM) of elements calculated using the concentrations of elements in the local basaltic rocks and those in groundwater showed that mobility decreased in the order of B > Rb > Na > K > Mg > Ca > Mo > V > Si > Sr > Sc > P > U > Zn > Pb > Cr > Cu > Ba > Ni > Ti > (Mn, Al, Fe, Co, Th) indicating that oxyanion-forming elements and alkali metals had the highest mobility. Compared to average RM, V had decreased mobility, and Fe and Mn had increased mobility in anoxic groundwater while V, Mo, and U had higher mobility in oxic-alkaline water. The sources of V, Cr, Cu, and Zn in rocks were estimated using the partition coefficients between minerals and basaltic melt, and the disparity between sources and mobility indicated that sinks are more important for controlling the concentrations of these elements in groundwater than the contents in the rocks. Principal component analysis (PCA) of hydrogeochemical parameters in groundwater produced three principal components (PC) which represent dissolution of basaltic rocks without significant attenuation of released solutes, higher degree of water–rock interactions resulting in oxic-alkaline conditions, and attenuation of Zn and Cu in higher pH, respectively. Spatial distribution of PCs revealed that groundwater with elevated concentrations of mobile elements was concentrated in the southwestern area and that concentrations of V and Cr were more scattered, which is likely to be controlled by pH and redox states of groundwater as well as degree of water–rock interactions. 相似文献
10.