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1.
天然成因的高氟地下水是世界范围内备受关注的环境问题和饮用水安全问题。前人对高氟地下水的形成过程已开展了大量研究,但是对于高原盆地复杂水文地质条件下不同类型含水层组(第四系松散层含水层、基岩裂隙或岩溶含水层以及新生代古近纪以来的碎屑岩含水层)高氟地下水的分布和形成过程尚不明确。本文以化隆—循化盆地为研究区,通过采集、测试研究区内的各类地下水样品,分析研究区内不同类型含水层中地下水的化学特征及同位素特征。结果表明,高氟地下水(1.007.73 mg/L)主要分布在沿黄河的河谷区域和巴燕低山丘陵区域的泉水和潜水中以及深部的承压水中,在垂向上高氟地下水无明显分布规律。接受黄河水入渗补给的河谷潜水中氟离子浓度较低,补给黄河的河谷潜水中氟离子浓度较高。贫钙富钠的弱碱性苏打型水有利于地下水中氟的富集。泉水和潜水中氟主要来源于萤石的溶解,而承压水中氟除了来源于萤石外,还来源于其他含氟矿物。对于潜水和第四系松散层泉水,蒸发浓缩作用促进了地下水中氟的富集。另外,阴离子竞争吸附作用、阳离子交换吸附作用是泉水(第四系松散层泉水和基岩裂隙泉水)和潜水中氟元素富集的主要原因,而承压水中氟离子浓度受竞争吸附作用影响较大,阳离子交换吸附作用影响较小。研究成果可为化隆—循化盆地低氟地下水的勘查和开发提供科学依据。  相似文献   

2.
山东省高密市地处胶莱盆地,南部为丘陵区,中部为缓坡区,北部为高氟地下水分布的平原区,属于盆地浅层地下水型饮水高氟地区,是全国氟中毒较为严重的地区之一。该区地势平坦,属暖温带大陆季风气候区,蒸发强度较高。晚更新世以来,该区较为平稳,地表水、地下水径流滞缓,地下水以降水补给、蒸发排泄为主,目前兼有少量的人工开采。高氟地下水赋存于白垩纪火山碎屑岩风化残积形成的第四系松散堆积物中,含水层以砂质亚粘土为主,在埋深0.5~1.0 m处普遍发育钙质结核,俗称姜石。靠近北部河流,第四系底部多发育一层厚度渐大的含砾砂层。随着砂层的出现、增厚,地下水中的含氟量逐渐降低。据此总结了高密市高氟地下水的成因模式,为溶滤富集型与蒸发浓缩碱化型的复合模式。通过室内淋溶试验,结合当地的实际,提出“原位驱氟”的设想。  相似文献   

3.
大荔潜水含水层中氟的赋存规律及水化学成因   总被引：1，自引：0，他引：1  
大荔县地处渭河断陷盆地东部,潜水中氟含量较高,氟的赋存受水文,气候,地形地貌、地质背景、水文地质、水文地球化学等多种因素的制约,根据浅层地下水调查资料采用美国地质调查局的PHREEQC软件来研究地下水中氟赋存规律.该地区降雨量小,蒸发强烈,高氟水的成因可分为,蒸发浓缩型和溶滤富集型.岩性主要为黏土、亚黏土、细砂,孔隙小,富含氟的矿物成分为地下水中高氟提供了丰富的物质来源.地下水水位埋深浅,包气带中毛细上升高度高,导水性差,多层交互含水层结构为高氟地下水提供了得天独厚的赋存条件.结合水文地球化学的作用,研究了氟与其主要络合离子的存在形式和组分浓度以及它们的矿物来源的溶解-沉淀情况,来揭示氟在地下水径流方向上的演化规律.  相似文献   

4.
大同盆地高氟地下水的分布特征及形成过程分析   总被引：2，自引：0，他引：2  
大同盆地是典型的高氟地下水分布区,其分布规律和成因在类似地区具有代表性。在对盆地地下水水化学特征和空间变化特征分析的基础上,深入讨论了高氟地下水的空间分布规律、控制因素及其形成的水文地球化学过程。结果表明,整个盆地浅层孔隙水中的氟质量浓度普遍较高,变化范围为0.29~6.22mg/L,平均值为1.82mg/L。氟质量浓度高值区主要分布于盆地中部和北部,呈现出由盆地边缘至盆地中心,质量浓度趋向于升高的变化规律。强烈的蒸发浓缩作用以及高pH、高碱度、高钠低钙含量的水化学特征有利于氟富集。大同盆地高氟地下水的形成是含氟矿物的溶解、离子交换和蒸发浓缩作用等水文地球化学过程共同作用的结果。  相似文献   

5.
由于地表水资源稀缺,地下水是塔里木盆地南缘绿洲带重要用水水源,因此,系统查明该区地下水砷氟碘的分布及成因至关重要。基于塔里木盆地南缘绿洲带233组地下水水样检测结果,分析不同含水层中高砷、高氟和高碘地下水的空间分布及水化学特征,结合研究区地质、水文地质条件和地下水赋存环境进一步揭示影响地下水砷氟碘的来源、迁移与富集的水文地球化学过程。结果表明:地下水砷、氟、碘浓度变化范围分别为1.091.2 μg/L、0.0128.31 mg/L、10.02 637.0 μg/L。地下水高砷、高氟和高碘水样分别占总水样的7.3%、47.2%和11.6%,砷氟碘共富集占比为3.0%。砷氟碘共富集地下水主要分布于研究区中部的民丰县,水化学类型主要为Cl·SO4-Na型。自补给区至过渡区再至蒸发区,地下水氟、碘浓度明显增大,砷浓度在过渡区和蒸发区均较大;砷氟碘共富集地下水取样点主要分布于36.060.0 m深度的浅层承压含水层中。浅层地下水受蒸发作用和矿物溶解沉淀作用的影响,随砷氟碘富集项的增多而增大。第四纪成因类型中风积物对氟浓度的影响较大,洪积-湖积物对砷和碘浓度的影响较大。细粒岩性、平缓的地形、地下水浅埋条件、偏碱性的地下水环境、微生物降解作用下有机质介导的矿物溶解是利于砷氟碘共富集的主要机制。  相似文献   

6.
张掖盆地水文地质特征与稳定同位素研究   总被引：1，自引：0，他引：1  
张徽  安永会  韩双宝  何锦  李旭峰 《地下水》2009,31(6):123-125
论述了张掖盆地地下水赋存分布特征与地下水补给、径流、排泄条件,利用水化学、同位素调查的方法,重点对张掖甘州平原区地下水水化学类型及其演化过程进行了研究。结果表明：张掖盆地由源于南部祁连山和北部龙首山的水系沉积物组成,其冲洪积平原规模、含水层富水性、导水性与地下水水化学特征等方面存在差异;同时地下水稳定同住素特征分析印证了水文地质条件的差异。祁连山前沉积物与龙首山前沉积物中地下水有着不同的补给来源和径流路径。浅层地下水和龙首山前深层承压水主要补给源为大气降水和山区河流入渗补给,祁连山前深层承压地下水系统可能有冰雪融水补给。  相似文献   

7.
云应盆地东北部属鄂北贫水地区,赋存于古近系—第四系含水层中的地下水是当地生产、生活用水的主要来源,亟需查明含水层的结构、含水层间地下水的转化关系等基本条件,为研究区内合理开发利用地下水提供依据。本研究通过野外水文地质调查、水文地质钻探工作,将研究区划分为单层含水层与双层含水层结构两个亚区（6个小区）。并通过地下水水位动态长期监测,获取了区内不同含水层的水位动态变化特征,分析各含水层之间的水力联系,建立了区域地下水转化的概念模式,即:研究区地下水以接受山前降雨入渗及风化裂隙水侧向径流补给为主,主要以水平径流的形式经古近系孔隙-裂隙含水层及第四系孔隙承压含水层往澴水方向运移,而后进入第四系孔隙潜水含水层。地下水和地表水在不同季节补排模式不同,雨季地表水（澴水）补给地下水,旱季地下水向地表水（澴水）排泄。古近系孔隙-裂隙水与上覆第四系孔隙水联系密切互为补给,共同构成具有统一水力联系的垂向多层结构的含水系统。独特的含水层结构决定了区内地下水接受降水补给的条件较差,地下水可开采资源量总体较贫乏,建议重点利用区域地表水资源,适度开发地下水资源,推进农业节水灌溉工程,实现水资源可持续利用。  相似文献   

8.
敬信盆地第四系下更新统沉积环境以冲积扇相为主,发育有下部孔隙承压含水层(Mx);中上更新统以湖泊相为主,发育有上部孔隙承压含水层(Ms);孔隙潜水含水层的的发育层位为全新统。盆地内各层位地下水的补给来源主要为大气降水,上、下孔隙承压水主要靠孔隙潜水越流补给,其动态变化滞后于孔隙潜水近一个月,地下水向图们江径流、排泄。潜水含水层富水性较弱,水化学类型复杂;承压含水层富水性强,上部承压含水层水质优良,下部承压含水层水质稍差,水中Fe、Mn含量较高,并沿图们江向下游有增高的趋势。  相似文献   

9.
敦煌盆地地下水水化学特征及水质评价   总被引：2，自引：0，他引：2  
通过对敦煌盆地38个地下水样品的采集和测试,运用描述性统计法和因子分析法对地下水的化学特征及其成因进行了分析。在此基础上,利用美国农业部(USDA)评价方法和Wilcox图解法对地下水质进行了评价。研究结果表明:敦煌盆地浅层地下水中主要阳离子为Ca~(2+)、Na~+、Mg~(2+),主要阴离子从补给区→径流区→排泄区由HCO_3~-→SO_4~(2-)→Cl~-转换;深层地下水中阳离子以Na~+、Mg~(2+)为主,阴离子主要为Cl~-、SO_4~(2-)、HCO_3~-,且三者含量较为接近;影响盆地内地下水化学特征的主要因素为蒸发浓缩作用和矿物的溶解作用;水质评价结果显示,可作为农作物灌溉用水的水样约占总水样的26.3%,分布在党河洪积扇扇顶补给区、扇中与扇缘径流区和盆地东南部细土平原径流区。  相似文献   

10.
通过水文地质调查、水样采集,结合地下水流动系统、吉布斯图、Piper三线图,对程家营盆地地下水水化学特征进行研究;结果表明,该区地下水呈弱碱性,水质较好,TDS、COD浓度较低,水化学类型为HCO_3-Ca;F~-、Mg~(2+)主要受物质来源和山泉水影响;受水-岩相互作用影响,地下水Na~+、Cl~-、HCO_3~-沿地下水径流方向逐渐升高;SO_4~(2-)、K~+表现出沿地下水径流方向逐渐降低趋势;河流沿岸阶地区域地下水径流速度慢、水位埋深浅,受蒸发浓缩作用影响较强形成高TDS地下水;Ca~(2+)离子随受水温和SO_4~(2-)离子浓度升高而降低。程家营盆地地下水水化学特征研究成果,对该区地下水资源的管理、保护以及可持续开发具有重要意义。  相似文献   

11.
A hydrochemical investigation was conducted in the Ejina Basin to identify the hydrochemical characteristics and the salinity of groundwater. The results indicate that groundwater in the area is brackish and are significantly zonation in salinity and water types from the recharge area to the discharge area. The ionic ration plot and saturation index (SI) calculation suggest that the silicate rock weathering and evaporation deposition are the dominant processes that determine the major ionic composition in the study area. Most of the stable isotope δ18O and δD compositions in the groundwater is a meteoric water feature, indicating that the groundwater mainly sources from meteoric water and most groundwater undergoes a long history of evaporation. Based on radioactive isotope tritium (3H) analysis, the groundwater ages were approximately estimated in different aquifers. The groundwater age ranges from less than 5 years, between 5 years and 50 years, and more than 50 years. Within 1 km of the river water influence zone, the groundwater recharges from recent Heihe river water and the groundwater age is about less than 5 years in shallow aquifer. From 1 km to 10 km of the river water influence zone, the groundwater sources from the mixture waters and the groundwater age is between 5 years and 50 years in shallow aquifer. The groundwater age is more than 50 years in deep confined aquifer.  相似文献   

12.
We investigated major ions, stable isotopes, and radiocarbon dates in a Quaternary aquifer in semi-arid northwestern China to gain insights into groundwater recharge and evolution. Most deep and shallow groundwater in the Helan Mountains was fresh, with total dissolved solids <1,000 mg L?1 and Cl? <250 mg L?1. The relationships of major ions with Cl? suggest strong dissolution of evaporites. However, dissolution of carbonates, albite weathering, and ion exchange are also the major groundwater process in Jilantai basin. The shallow desert groundwater is enriched in δ18O and intercepts the local meteoric water line at δ18O = ?13.4 ‰, indicating that direct infiltration is a minor recharge source. The isotope compositions in intermediate confined aquifers resemble those of shallow unconfined groundwater, revealing that upward recharge from intermediate formations is a major source of shallow groundwater in the plains and desert. The estimated residence time of 10.0 kyr at one desert site, indicating that some replenishment of desert aquifers occurred in the late Pleistocene and early Holocene with a wetter and colder climate than at present.  相似文献   

13.
The hydrodynamic groundwater data and stable isotopes of water have been used jointly for better understanding of upward leakage and mixing processes in the Djerid aquifer system (southwestern Tunisia). The aquifer system is composed of the upper unconfined Plio-Quaternary (PQ) aquifer, the intermediate (semi-)confined Complex Terminal (CT) aquifer and the deeper confined Continental Intercalaire (CI) aquifer. A total of 41 groundwater samples from the CT and PQ aquifers were collected during June 2001. The stable isotope composition of waters establishes that the CT deep groundwater (depleted as compared to present Nefta local rainfall) is ancient water recharged during late Quaternary time. The relatively recent water in the shallow PQ aquifer is composed of mixed water resulting from upward leakage and sporadic meteoric recharge. In order to characterize the meteoric input signal for PQ in the study area, rainfall water samples were collected during 4 years (2000–2003) at the Nefta meteorological station. Weighted mean values of isotopic contents with respect to rainfall amounts have been computed. Despite the short collection period in the study area, results agree with those found in Beni Abbes (southwestern Algerian Sahara) by Fontes on 9 years of rainfall surveillance. Stable isotopic relationships provide clear evidence of shallow PQ aquifer replenishment by deep CT groundwater. The 18O/upward leakage rate allowed the identification of distinctive PQ waters related to CT aquifer configuration (confined in the western part of the study area, semi-permeable in the eastern part). These trends were confirmed by the relation 18O/TDS. The isotope balance model indicated a contribution of up to 75% of the deep CT groundwater to the upper PQ aquifer in the western study area, between Nefta and Hazoua.  相似文献   

14.
吕晓立  刘景涛  周冰  朱亮 《中国地质》2020,47(6):1765-1775
以新疆塔城盆地80组地下水样品水化学组分测试结果为依据，结合区域地质、水文地质调查资料，研究塔城盆地地下水中铁、锰分布特征及其成因。结果表明，研究区浅层地下水中铁、锰浓度总体较低，局部超标，其空间分布特征基本一致。对比2017年发布的地下水质量标准，地下水中铁、锰超标率依次为25%和5%，深层承压水铁、锰含量均未超标。地下水中铁锰离子浓度受原生地质环境所控，同时叠加人类活动影响，城镇周边人口密集区尤其是排污沟渠附近地下水中耗氧量、溶解性总固体、铁、锰含量明显升高。地下水中铁锰超标连片区域呈条带状或斑块状分布于塔城盆地北部山区、中部冲积平原区以及南部低山丘陵区的铜钼成矿带，受人类活动影响，在塔城市、额敏县及其周边的地表水和地下水重污染区分布有地下水铁、锰重污染点，污染物特别是有机污染物排放所引起的还原环境促使地层中难溶的铁锰矿物的溶解释放。地层中，尤其是矿床及周边地层中高含量的铁锰是地下水中铁锰的重要来源，沉积层中富含丰富的有机质同时叠加人类活动输入所形成的还原条件是研究区地下水中铁、锰迁移和富集的主控因素。  相似文献   

15.
Deuterium, oxygen-18 and chloride were analyzed for 84 samples from deep and shallow wells, precipitation and the river White Nile to investigate groundwater recharge/discharge relations in the semi-arid central Sudan. Spatial and vertical variation in isotopic signature and chloride concentration in the groundwater show similar patterns and indicate local recharge and evaporative discharge. Progressive decrease in isotopic composition along the regional groundwater flow path demonstrates aquifer continuity down the NW–SE recharge-discharge path. Isotope-heavy recharged water progressively mixes with lighter older groundwater formed during cooler and humid conditions in the late Pleistocene. However, evaporative fractionation in the flow path’s final reach in the southeast re-enriches the isotopic composition and suggests evaporative loss of groundwater as the plausible discharge mechanism. Chloride concentration increases down the gradient from the recharge area and reaches its peak in the discharge zones indicating: lack of recharge from direct infiltration down the gradient, evaporation and prolonged rock/water interaction. Head differences and increased isotopic concentration in the vicinity of the White Nile suggest recharge from the river from subsurface flow. Reduced chloride content and relatively heavier isotopic composition in the deep groundwater beneath the wadi of Khor Abu Habil indicate recharge from the streambed into the deep aquifer.  相似文献   

16.
This paper describes the use of multivariate statistical analysis to trace hydrochemical evolution in a limestone terrain at Zagros region, Iran. The study area includes a deep confined aquifer, overlaid by an unconfined aquifer. The method involves the use of principal component analysis (PCA) to assess and evaluate the hydrochemical evolution based on chemical and isotope variables of 12 piezometers drilled in both the unconfined and confined aquifers. First PCA on all variables shows that water–rock interaction under different conditions with respect to the atmospheric CO2 is the main process responsible for chemical constituents. As a result, combinations of several ratios such as Ca/TDS, SO4/TDS and Mg/TDS with physico-chemical and isotope variables reveal different hydrochemical evolution trend in the aquifers. Second PCA on the selective samples and variables reveals that displacement of the unconfined samples from dry to wet season follows a refreshing trend towards river samples that is characterized by reducing electrical conductivity and increasing sulphate and tritium contents. However, the refreshing trend cannot be traced in the confined aquifer samples suggesting no recharge from river to the confined aquifer. Third PCA reveals that, chemical composition of water samples in the unconfined aquifer tends to have considerable difference from each other in the end of recharge period. In contrast, the confined aquifer samples have a tendency to show similar chemical composition during recharge period in comparison to end of dry period. This difference is caused by different mechanism of recharge in the unconfined aquifer (through the whole aquifer surface) and the confined aquifer (through the limited recharge area).  相似文献   

17.
Process-based groundwater models are useful to understand complex aquifer systems and make predictions about their response to hydrological changes. A conceptual model for evaluating responses to environmental changes is presented, considering the hydrogeologic framework, flow processes, aquifer hydraulic properties, boundary conditions, and sources and sinks of the groundwater system. Based on this conceptual model, a quasi-three-dimensional transient groundwater flow model was designed using MODFLOW to simulate the groundwater system of Mahanadi River delta, eastern India. The model was constructed in the context of an upper unconfined aquifer and lower confined aquifer, separated by an aquitard. Hydraulic heads of 13 shallow wells and 11 deep wells were used to calibrate transient groundwater conditions during 1997–2006, followed by validation (2007–2011). The aquifer and aquitard hydraulic properties were obtained by pumping tests and were calibrated along with the rainfall recharge. The statistical and graphical performance indicators suggested a reasonably good simulation of groundwater flow over the study area. Sensitivity analysis revealed that groundwater level is most sensitive to the hydraulic conductivities of both the aquifers, followed by vertical hydraulic conductivity of the confining layer. The calibrated model was then employed to explore groundwater-flow dynamics in response to changes in pumping and recharge conditions. The simulation results indicate that pumping has a substantial effect on the confined aquifer flow regime as compared to the unconfined aquifer. The results and insights from this study have important implications for other regional groundwater modeling studies, especially in multi-layered aquifer systems.  相似文献   

18.
Stable isotopes (δ18O, δ2H and 13C) and radioactivity (3H, 14C) have been used in conjunction with chemical data to evaluate the processes generating the chemical composition, reconstruct the origin of the water and groundwater residence time. The Aleppo basin is comprised of two main limestone aquifers: the first one is unconfined of Paleogene age and the second is confined of Upper Cretaceous age. The chemical data indicate that the dissolution of minerals and evaporation are the main processes controlling groundwater mineralization. The groundwater from the two aquifers is characterized by distinctive stable isotope signatures. This difference in water isotopes is interpreted in terms of difference origin and recharge period. Fresh and brackish shallow groundwater were mostly recharged during the Holocene period. The presence of 3H in several groundwater samples of this aquifer gives evidence that groundwater recharge is going on. Brackish water of the deep confined aquifer has depleted stable isotope composition and very low 14C activity that indicates recharge during the late Pleistocene cold period.  相似文献   

19.
Stable isotopes (??2H, ??18O and ??13C) and radiocarbon (14C) have been used in conjunction with chemical data to evaluate recharge mechanisms and groundwater residence time, and to identify inter-aquifer mixing in the Djeffara multi-aquifer in semi-arid southeastern Tunisia. The southern part of this basin, the Djeffara of Medenine aquifer system, is comprised of two main aquifers of Triassic and Miocene sandstone. The Triassic aquifer presents two compartments; the first one (west of the Medenine fault system) is unconfined with a well-defined isotope fingerprint; the second compartment is deeper and confined. Multi-tracer results show groundwater of different origins, ages and salinities, and that tectonic features control groundwater flows. Fresh and brackish groundwater from the unconfined part of the Triassic aquifer was mostly recharged during the Holocene. The recharge rates of this aquifer, inferred by 14C ages, are variable and could reach 3.5?mm/year. Brackish water of the deep confined part of the Triassic aquifer has stable isotope composition and 14C content that indicates earlier recharge during late Pleistocene cold periods. Brackish to saline water of the Miocene aquifer presents variable isotope composition. Groundwater flowing through the Medenine fault system is mainly feeding the Miocene aquifer rather than the deep confined part of the Triassic aquifer.  相似文献   

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