北京市城近郊区地下水的环境同位素研究

应用环境同位素方法,研究北京城近郊区地下水演化规律。沿北京市永定河冲洪积扇地下水流动方向取样15组(D、18O、T、14C及全分析),对所取水样进行D、18O、T、14C分析,并确定地下水同位素年龄。运用地下水14C和T含量在垂向和水平方向变化的结果,验证了地下水的流向并计算了地下水的流速变化范围为5·02~62·63m/a,从山前至平原浅层地下水径流速度逐渐变小,反映了地下水水平径流强度逐渐减弱,地下水交替逐渐变差;浅层孔隙水以垂向交替为主,深层孔隙水以水平径流为主。对地下水D、18O之间的关系进行分析,从而判断地下水的补给来源等。     

北京市平原区地下水循环特征的同位素研究

同位素技术是研究区域地下水循环规律的主要手段之一。本文对平原区地下水进行了取样分析,运用同位素技术并结合水文地质条件,研究了北京市平原区地下水循环演化规律。运用^3H和^14C的测年技术确定了地下水年龄;利用D和18^O关系曲线探讨了地下水的起源;按照是否积极参加了现代水循环的原则将第四系地下水划分为浅层水和深层水;对浅层水和深层水的更新状况进行了研究。研究表明,浅层水广泛分布于北京平原区,径流条件好,更新快;深层水主要分布于永定河、潮白河冲洪积扇下部及冲洪积平原的深部地区,补给条件相对差,与现代大气降水联系弱,径流条件差,更新慢。     

氚同位素在黑河流域水循环研究中的应用

通过对黑河流域不同水体如降水、河水、深井（>80m） 、浅井（<80m）及泉水的氚（T）含量的测定,结合文献资料和国际原子能机构数据,对流域不同水体氚（T）含量的空间分布特征进行了分析,并对黑河流域浅层和深层地下水的补给来源、年龄及其更新时间进行了研究。结果表明：1）黑河上游、中游及下游河水T含量分别为50.0TU,33.3TU及20.9TU,呈逐渐降低趋势;上游和中游降水T含量变化也呈相似的规律,说明黑河流域河水来自黑河源区降水,且河水从上游到下游流动过程中与地下水进行转换。尤其是在临泽到正义峡段,河水的平均T含量为31.9TU,说明张掖和临泽灌溉抽提的地下水对河水有补给作用。2）黑河上游和中游山前平原的深层地下水T含量大于30.0TU,补给年龄小于50a;中游盆地及下游深层地下水T含量低于10.0TU,地下水年龄在50a以上,为次现代水,更新速度慢。3）黑河上游地下水和河道附近区域的浅层地下水的T含量高于30.0TU,补给年龄低于50a;远离河道浅层地下水T含量低于10.0TU,补给年龄大于50a。说明黑河源区降水是上游地下水的补给源,出山径流是黑河干流附近浅层地下水的主要补给源,地下水补给年龄低于50a,更新期短;远离河道区域的浅层地下水T含量低于10.0TU,为次现代水,更新速度慢。本研究结果对合理科学地利用黑河流域水资源具有借鉴意义。     

同位素技术在某核废处置场区水文地质条件研究中的应用

本文通过对研究区各类地下水化学成分、水中氢、氧稳定同位素及放射性同位素的研究，区分出浅层地下水（孔隙水）和基岩风化裂隙水。确定了地下水的补给区为排牙山区；地表水、地下水迳流的主要方向为ＳＥ向，同时存在地下水侧向迁移，并以泉的形式补给浅层水和地表水。通过氚的衰变计算及与香港观测站的资料对比，确定了区内地下水的相对年龄，并将其分为３个年龄组：（１）迳流时间最短的地下水，具近期大气降水的氚浓度；（２）相对年龄为２０年左右的浅层地下水；（３）相对年龄大于３０年的低氚水。     

秦皇岛洋河-戴河冲洪积平原第四系含水层海水入侵机理分析

通过对秦皇岛洋河-戴河冲积平原地区枣园水源地野外调查和不同水样的水文地球化学及多种同位素测试分析发现:1)该区海水入侵过程中的水化学作用主要是海水与粘土含量高的地层中钙质矿物阳离子的交换;2)海水入侵不是沿含水层整体向前推移,而是存在优先入侵通道(如断层和水势差较大水流方向)和局部入侵速度较快的现象;3)深层和浅层地下水水力联系较大,海水入侵已经影响到深层地下水;4)研究区地下水平均氚浓度为9.86 TU,地下水平均年龄介于17.6a~23.7 a之间,地下水流速约为2.11 m/a,整体上地下水循环路径短,径流速度快,地下水交替强烈.这些结果可为以后进一步治理海水入侵和合理利用地下水提供依据.     

喀什平原区地下水同位素年龄特征及更新速率分析

为分析喀什平原区300 m以浅地下水年龄和更新速率,准确划分地下水流系统,采用了3H和14C放射性同位素测试方法,对采集的120组地下水样品中3H和14C同位素组成进行了分析,研究了喀什平原区不同区域地下水的年龄特征。结果表明,研究区大部分潜水氚值为12.2~39.6 TU,地下水年龄从山前冲洪积砾质平原至细土平原区逐渐增大,为10~50年;在中部库木塔格背斜隆起一带,潜水氚值小于10 TU,地下水年龄大于500年,形成地下水年龄分水岭;区内地下水14C年龄约为2 000~13 000年,反映了地下水补给时段差异较大。从山前冲洪积砾质平原上游至冲积细土平原中部地区,地下水更新速率约为2%~7%,属积极交替带;冲积细土平原中下游地区,地下水更新速率约为1%~2%,属较积极交替带;在冲积细土平原下游地区,地下水更新速率均小于1%,属弱交替带。     

基于同位素和水化学的北京平谷盆地地下水循环研究

通过在区域开展地下水同位素、水化学取样分析，研究了平谷泃河和洳河冲洪积扇地下水循环演化特征。分析结果显示：本次所取水样pH值为7.6～8.1，为中性水；阳离子含量均以Ca²⁺、Mg²⁺为主，占70%以上，阴离子含量以HCO₃^-为主，占82%以上，所取水样地下水水化学类型均为HCO₃·Ca·Mg型。研究区浅层第四系松散孔隙水δ²H值和δ¹⁸O值分别为64.9‰、9.08‰，深层第四系松散孔隙水δ²H值和δ¹⁸O值分别为67.6‰、δ₁₈O值，基岩岩溶水δ²H值和δ¹⁸O值分别为64.5‰、9.36‰。基岩岩溶水稳定同位素含量均值与浅层地下水比较接近；浅层第四系松散孔隙水¹⁴C含量为46.7%～93.1%，深层水第四系松散孔隙水¹⁴C含量为40.23%～61.13%，基岩岩溶水^...     

同位素指示的巴丹吉林沙漠南缘地下水补给来源

通过恢复巴丹吉林沙漠及其周边地区大气降水氚值，并结合区域稳定同位素组合特征，揭示了区域地下水氚年龄的多解性与地下水稳定同位素的温度效应。恢复的1963年核试验期氚高峰值达到2 100 TU，进入90年代平均为60 TU。1960年以来降水补给的地下水氚值都应大于15 TU，而1963年的高峰氚衰变至今应在200 TU左右。地下水实测氚值较低，表明由现代少量降水补给的地下水与大量的古水进行了混合。影响降水中δ18O和δ2H分布的主要影响因子是月平均空气温度，对δ18O与δ2H的影响权重分别占到59.9%和57.0%。巴丹吉林沙漠及其周边地区地下水较低的稳定同位素组成表明，其补给主要是晚更新世较冷环境下形成的，来源于东南部的雅布赖山区，部分浅层地下水接受现代降水与河流的补给。      

基于氢氧同位素示踪法矿坑水径流过程及补给来源研究

为了探明西南某矿山矿坑水的补给来源及受补给后的地下水径流过程,采用了氢氧同位素示踪法即(2H、18O)及放射性氚(3H)进行分析研究。研究结果发现:矿坑水最终来源于近期大气降水补给,地下水整体径流过程为部分浅层水补给深层承压水,部分深层承压水通过拖顶越流方式补给浅层水,说明矿区因各形态断层的密集发育,原有的砂页岩隔水层部分地段丧失了隔水性能,使地下水含水系统成为统一的含水体。     

金华地区地下水同位素特征及更新能力研究

金华地区位于金衢盆地东段,对其地下水同位素特征及更新能力研究对于整个盆地地下水资源研究具有重要意义,通过分析研究区内稳定同位素氘(D)和氧(~(18)O)以及放射性同位素氚(~3H)和碳(~(14)C)的空间分布特征,建立了金华地区降水线方程为:δD=8.29δ~(18)O+15.9,讨论了地表水、潜水、红层地下水的环境同位素的组成特征,对潜水及红层地下水的更新能力进行了评价。结果表明,金华地区降水线方程斜率及截距均大于全球大气降水;潜水、红层地下水及地表水三者联系密切;潜水、红层地下水在接受降水的补给后经历了不同程度的蒸发作用;红层地下水D和~(18)O同位素明显向下游富集;潜水~3H值介于6.6～19.0TU,~(14)C年龄显示为现代水,因此其可更新能力较强,红层地下水放射性~(14)C年龄为3020～5360BP,可更新能力较弱,红层地下水3H值介于4.4～12.3TU,表明红层地下水中有现代水的混入,δ~(18)O随着地下水的年龄的增加而偏负。     

北京永定河流域地下水氢氧同位素研究及环境意义

利用氢氧同位素方法对北京地区永定河流域地下水状况及补给运移规律进行了研究。在系统采集了不同地点、不同深度的地下水样品的基础上,分析测试样品的δD、δ^18O、T。通过分析研究成果资料,初步判断出本区地下水的状况及补给运移规律：浅层地下水主要以近10a左右的“新水”为主,而且其主要补给方式是地表大气降水的垂直入渗补给;中深层地下水普遍混有“新水”,且新水比例有增大趋势;深层地下水基本以50a以上“老水”为主,但局部已混有“新水”。本区地下水的状况反映出浅层水补给深层水的越流现象普遍,这会引起深层地下水水质下降。由此可见,本区地下水水资源由于人工不合理的开采利用,状况不容乐观。     

Using environmental isotopes to evaluate the renewable capacity of a typical karst groundwater system in northern China

The karst groundwater in northern China is an important source of water supply. Its capacity for self-renewal is a key factor affecting its sustainable use. The Pingyi–Feixian karst aquifer in central and southern Shandong Province is a typical karst water source, contributing 54% to the total groundwater taken from the region. In this study, 25 groups of water samples were collected from the Pingyi–Feixian karst aquifer in November 2013. The compositions of isotopes of tritium (³H), carbon-13 (¹³C), and carbon-14 (¹⁴C) were measured. As indicated by the tritium values between 7.1 and 12.2 TU, the Pingyi–Feixian karst groundwater is primarily originated from both historical atmospheric precipitation and modern precipitation. The ¹⁴C ages corrected by δ¹³C were between 146 and 5403 years. Specifically, the shallow groundwater is younger than deep groundwater. Groundwater age tends to increase along the flow path. The ages of the groundwater in recharge area were between 146 and 1348 years, while the ages of deep groundwater in flowing area were generally between 2000 and 4000 years. The ages of the groundwater in discharge area with little anthropic exploitation were larger than 4500 years, whereas these with large amounts of exploitation were less than 1500 years. The shallower the groundwater, the stronger its capacity for renewal. The renewable capacity of karst groundwater in discharge area was significantly affected by anthropic exploitation. The karst groundwater in the areas with less exploitation showed the weakest capacity, whereas that in the area with intensive exploitation was much older and had a stronger renewable capacity.     

The Role of Groundwater Leakage through Deep Wells for the Deformation of Groundwater Flow: a Case Study in Cangzhou Area

Overexploitation of groundwater in Cangzhou area has attracted wide attention. Different layers of the aquifer may be connected through wells, since most wells of the deep aquifer have screens in several layers. This study proved the existence of vertical flow through wells, calculated the flow velocity and quantity of vertical flow in wells with methods of both field measurement and numerical simulation. Further, the recharge of deep groundwater by vertical flow through wells was estimated. An annual recharge of 1.5×108-2.8×108m3 from the third aquifer to the forth aquifer in Cangzhou area was estimated, according to the in-well measurement by heat pulse flowmeter sonde.     

Endangering of the Upper Jurassic karst-fissured aquifer in the Krakow Upland (southern Poland)

 A karst-fissured aquifer in the Upper Jurassic carbonate rocks of the Krakow Upland shows a very high yield (safe yield 117 000 m³/day) and belongs to the major groundwater basins (MGBs) of Poland. The uncovered character of the aquifer and its hydraulic structure favor the intensive infiltration and migration of anthropogenic pollutants from the surface. This pollution is caused by agriculture and industry in the proximity of Krakow and the Upper Silesian agglomeration. Progressive degradation of groundwater quality on a regional scale results. Evaluation of the endangering of the aquifer studied is based on the analysis of the time interval of vertical water percolation from the surface, the time interval of groundwater horizontal flow through the aquifer and the duration of water residence in the aquifer derived from tritium data. Quaternary and Cretaceous overburden occur in the Krakow Upland in addition to numerous outcrops of limestones. The time interval of vertical water percolation in highly permeable limestones does not exceed 3 years and in the areas covered by overburden it is from several to 50 years. The mean effective time interval of horizontal groundwater flow through the Upper Jurassic rocks along the flow paths ranges from several months in the areas of direct drainage to over 15 years in the elevated areas of local groundwater divides. The age of water in the rock matrix was determined using tritium data interpreted according to an exponential model and it ranges from 70 years to over 130 years. In karst-fissured systems with a high retardation index (R_p=21) the effective time of water circulation in local drainage basins does not exceed 7 years. The Krakow-Wieluń Upland is the most extensive and uniform karst region in Poland. It is a belt of Upper Jurassic limestone extending from Krakcow in the southeast to Wieluń in the northwest on the northeast slope of the Silesian Upland. Residual hills of Paleogene age separated by infilled karst depressions are the most characteristic features of the Krakow-Wieluń Upland. More than 800 small caves are known in this area, but only two of them reach 1 km of aggregate passage length (Gazek and others 1992). Received: 4 December 1996 · Accepted: 29 April 1997     

Spatial characteristics of water quality,stable isotopes and tritium associated with groundwater flow in the Hutuo River alluvial fan plain of the North China Plain

The groundwater flow system and the flow velocity in the alluvial fan plain of the Hutuo River, China, have been studied, with an emphasis on relating geochemical characteristics and isotopes factors. Seven stretches of one river, six springs and 31 wells, with depths ranging from 0 m (river waters) to 150 m, were surveyed. The groundwater has a vertical two-layer structure with a boundary at about 80–100 m depth, yielding an upper and a lower groundwater layer. The δ¹⁸O and δD values range from ?10.56 to ?7.05‰ and ?81.83 to ?59‰, respectively. The groundwater has been recharged by precipitation, and has not been subjected to significant evaporation during infiltration into the aquifer in the upper layer. Using a tritium model, the groundwater flow in the alluvial fan plain showed horizontal flow velocity to be greater than vertical velocity. Groundwater in the upper layer is characterized by Ca–HCO₃ type. From the spatial distribution characteristics of the stable isotope and chemical composition of the groundwater, agricultural irrigation was considered to have an influence on the aquifer by causing excessive groundwater abstraction and irrigation return.     

河北平原地下水14C年龄新认识

本文对河北平原第四系地下水14C年龄最新的结果进行了分析,得出如下认识:(1)垂向上,地下水的14C年龄随深度的增加而增大,或者沿地下水的流向而增大。但是,在同一孔组中,地下水埋深大于300m时出现了混乱现象。地下水14C年龄不但不增大,反而减小,其原因复杂;(2)水平方向上,第三含水组Q2地下水较老的年龄出现在河北平原中部,大致与子牙河方向一致,而第四含水组Q1地下水较老的年龄则呈北东东方向展布,即沧州—歧口一线分布,可能是地质结构影响所致。     

华北平原地下水年龄校正

地下水14C年龄一般指地下水和土壤CO2隔绝至今的年代.地下水测年在地下水水文学中占有特殊的位置,地下水测年可以用来确定补给区,估算地下水流速度、流量、补给速率、水力传导系数和有效孔L隙度,而且年龄数据还可以用来完善地下水流模型.本研究选择华北平原为重点研究区,利用地下水中的同位素和化学组分的测试结果,应用水文地球化学及同位素水文学等相关知识,通过六种传统模型和反向质量平衡模型(NETPATH)对华北平原地下水年龄进行校正.根据年龄校正结果,分析了深层地下水的年龄变化特点,确定了水流路径上发生的水文地球化     

Migration of arsenic in multi-aquifer system of southern Bengal Basin: analysis via numerical modeling

A heterogeneous anisotropic steady-state groundwater flow model for the multi-aquifer system of a part of southern Bengal Basin shows that human intervention has changed the natural groundwater flow system. At present, the shallow groundwater flow is restricted within the aquifer, with very short travel time of tens of years and vertical path length. The deep aquifer is fed by surface water or rainwater from distant locations with travel time of thousands of years and has no hydraulic connection with the arsenic-rich shallow aquifer. Numerical simulations indicate that the future pumping of deep groundwater is not likely to drive in arsenic from the shallow aquifer. Therefore, new wells may be installed in the deep aquifer. High pumping of shallow unpolluted aquifer consisting of brown sand will drive in groundwater containing organic matter from the post-Last Glacial Maximum aquifer-aquitard system. The organic matter drives reduction of manganese oxides at strip interfaces between palaeo-channel and palaeo-interfluve. After the completion of manganese reduction, FeOOH reduction may take place in the marginal palaeo-interfluvial aquifer and release sorbed arsenic. Arsenic then moves into the interior of palaeo-interfluvial aquifer polluting its fresh groundwater. Arsenic migration rates ranges between 0.21 and 6.3 and 1.3 × 10^?2 and 0.4 m/year in horizontal and vertical directions, respectively. Therefore, palaeo-interfluvial aquifer will remain arsenic-free for hundreds to thousands of years to supply safe drinking water.     

Hydrochemical characteristics and salinity of groundwater in the Ejina Basin, Northwestern China

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.