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21.
Tewodros Alemayehu Albrecht Leis Anton Eisenhauer Martin Dietzel 《Chemie der Erde / Geochemistry》2011,(2):177-187
Isotopic and chemical composition of groundwater from wells and springs, and surface water from the basalt-dominated Axum area (northern Ethiopia) provides evidence for the origin of water and dissolved species. Shallow (depth < 40 m) and deep groundwater are distinguished by both chemical and isotopic composition. Deep groundwater is significantly enriched in dissolved inorganic carbon up to 40 mmol l−1 and in concentrations of Ca2+, Mg2+, Na+ and Si(OH)4 compared to the shallow type.The δ2H and δ18O values of all solutions clearly indicate meteoric origin. Shifts from the local meteoric water line are attributed to evaporation of surface and spring water, and to strong water–rock interaction. The δ13CDIC values of shallow groundwater between −12 and −7‰ (VPDB) display the uptake of CO2 from local soil horizons, whereas δ13CDIC of deep groundwater ranges from −5 to +1‰. Considering open system conditions with respect to gaseous CO2, δ13CDIC = +1‰ of the deep groundwater with highest PCO2 = 10−0.9 atm yields δ13CCO2(gas) ≈ −5‰, which is close to the stable carbon isotopic composition of magmatic CO2. Accordingly, stable carbon isotope ratios within the above range are referred to individual proportions of CO2 from soil and magmatic origin. The uptake of magmatic CO2 results in elevated cations and Si(OH)4 concentrations. Weathering of local basalts is documented by 87Sr/86Sr ratios of the groundwater from 0.7038 to 0.7059. Highest values indicate Sr release from the basement rocks. Besides weathering of silicates, neoformation of solids has to be considered, which results in the formation of, e.g., kaolinite and montmorillonite. In several solutions supersaturation with respect to calcite is reached by outgassing of CO2 from the solution leading to secondary calcite formation. 相似文献
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24.
为查清罗城县地下水情况,根据罗城县地下水监测数据和水质特点,选取高锰酸盐指数、硝酸盐氮、总硬度、氨氮、铁和锰作为评价因子,以GB/T14848-93《地下水质量标准》为评价标准,同时运用内梅罗指数法和模糊综合评价法对罗城县9个地下水监测点位(饮用水水源保护区、工业园区和矿山开采区)进行地下水环境质量评价。以模糊综合评价结果进行分析,饮用水水源保护区内地下水质良好,均达到Ⅱ类水质标准;工业园区有1个点位地下水水质超标,超标因子为总硬度;矿山开采区地下水质情况较差,有2个点位监测因子铁、锰超标,为Ⅴ类水。最后,针对罗城县地下水现状及存在的问题,提出合理的对策建议。 相似文献
25.
As an in situ, simple and passive technology, Permeable Reactive Barrier (PRB) is becoming widely used in groundwater remediation. Based on its definition and development process, the development of PRB can be divided into two stages: The traditional zero-valent iron PRB before 2000 and the PRB composed of novel mixed media after 2000. With the rapid worsening of groundwater pollution, the increasing application of PRB and the rapid development of materials science, the development of PRB technology in future will be mainly focused on the investigation of mixed and novel media, the design of mixed PRBs, the combination of PRB technology with other remediation technology, and the long term monitoring and management of PRB projects. 相似文献
26.
地下水数值模拟是地下水资源评价的重要方法之一。应用GMS软件建立靖安水源地的地下水流数值模型,利用该模型对设计的不同开采方案进行模拟,预测降水保证率95%条件下各方案开采20年后的地下水流场变化及水位变化情况。结果表明,当水源地总开采量为10万m3/d时,地下水流场能够达到稳定状态,中心水位降深较小,不会对生态环境造成明显影响。 相似文献
27.
地下水质量评价为保护和开发地下水资源,防止和控制地下水污染,保障人民身体健康提供科学依据。结合相关地下水调查资料采用单指标评价、内梅罗指数和模糊综合评价三种方法,对包头市地下水水质分别进行评价,通过对评价结果综合分析认为:模糊综合评价结果更符合区域地下水总体特征,包头市潜水Ⅳ类、Ⅴ类占到取样点总数的36%,质量整体较差;承压水Ⅰ—Ⅲ类遍及包头市全区,质量整体较好。 相似文献
28.
以黄河上游某灌区的地下水为研究对象,分别建立灌区潜水的DASLTCU模型和承压水DLCA模型对灌区地下水进行防污性能评价。选取潜水埋深(D)、含水层厚度(A)、地表土层厚度(S)、地表坡度(L)、地表岩性(T)、含水层渗透系数(C)、灌区现状图(U)作为灌区潜水的综合防污性能评价因子;选取承压水埋深(D)、隔水层岩性(L)、隔水层连续性(C)、隔水层厚度(A)作为灌区承压水的防污性能评价因子;应用ARCGIS和MODELFLOW对灌区地下水的综合防污性能进行评价和预测。得出现有灌溉规模下,潜水综合防污性差及较差地区占总面积24%,中等及以上地区占76%,灌区综合防污性总体较好。绘制出灌区潜水的现状防污性能分区图及30年后潜水的综合防污性能预测分区图。 相似文献
29.
Chemical data are used to clarify the hydrogeological regime in the Mafraq area in northern Jordan, as well as to determine
the status of water quality in the area. Groundwater from the shallow aquifer in the Mafraq area can be divided into two major
groups according to geographical locations and chemical compositions. Water in the basaltic eastern part of the study area
is characterized by the dominance of chloride, sulfate, sodium, and potassium, whereas waters in the limestone aquifers in
the west are dominated by the same cations but have higher concentrations of bicarbonate. Stable isotopes show that the shallow
aquifers contain a single water type which originated in a distinct climatic regime. This water type deviates from the Global
Meteoric Water Line (MWL), as well as from the eastern Mediterranean meteoric water line. The waters are poor in tritium,
and thus can be considered generally older than 50 years. Chemical mass balance models suggest that water is moving from the
west towards the north of the study area. This suggests that waters from the different basins are separated from each other.
Degradation of water quality can be attributed to agricultural fertilizers in most cases, although the waste-water treatment
plant at Khirbet es Samra is a contributor to pollution in the southwestern part of the study area.
Received: 20 August 1997 · Accepted: 3 February 1998 相似文献
30.
针对白沙河地下水含水层的内部结构和本区开采特点以及已出现的环境问题,建立了地下水资源管理模型,确定了优化开采方案。该管理模型针对本区每年2个管理时段的长度及其开采量均不同的特点,导出了新的响应矩阵的公式。管理模型的建立有助于对该区地下水的合理开采。 相似文献