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1.
地下水硝酸盐污染已成为一个普遍的环境问题.为研究重庆金佛山水房泉岩溶地下河系统的硝酸盐来源与转化，于2017年4-10月每24 d左右对地下河系统内的某酒店自来水、化粪池、1#落水洞、水房泉4个采样点开展监测，进行水化学和δ15Nnitrate、δ18Onitrate同位素分析.某酒店污水经化粪池处理后，由1#落水洞排入地下河，最后在水房泉排泄.结果表明：①水房泉NO3-浓度范围为4.65~10.20 mg/L，相对于我国生活饮用水标准处于较低水平；化粪池、1#落水洞、水房泉3个采样点电导率和NO3-、Cl-浓度的高值期与游客人数增多对应关系较好.②某酒店自来水δ15Nnitrate值为3.7‰~5.8‰、δ18Onitrate值为1.6‰~2.7‰，说明硝酸盐主要来源为土壤有机氮，处于自然背景值；1#落水洞δ15Nnitrate值为14.4‰~21.1‰、δ18Onitrate值为3.5‰~11.2‰，显示硝酸盐主要来源为粪肥污水；化粪池和水房泉的δ15Nnitrate值为3.7‰~17.0‰、δ18Onitrate值为-9.0‰~7.3‰，表明硝酸盐主要来源为土壤有机氮与粪肥污水，显示其硝酸盐主要污染源是酒店生活废污水.③某酒店自来水、水房泉地下水的硝酸盐转化过程以同化作用为主；化粪池污水以硝化作用为主，是岩溶地下河系统硝酸盐的重要来源之一；1#落水洞污水表现为反硝化作用.④基于SIAR模型对水房泉的硝酸盐来源进行定量解析，发现大气降水、土壤有机氮和粪肥污水的贡献率分别为28%、36%和36%左右. 相似文献
2.
稳定同位素技术在地表水硝酸盐污染研究中的应用 总被引：4，自引：1，他引：3
地表水硝酸盐污染已成为全球面临的主要水环境问题之一,为了有效控制地表水中硝酸盐污染,确定地表水中硝酸盐的来源以及研究其在环境中的迁移转化过程就显得尤为重要.硝酸盐稳定氮(15N)、氧(18O)同位素作为一种有效的示踪技术在识别地表水中硝酸盐的来源及迁移转化过程中已得到了广泛的应用,但是硝酸盐在迁移转化过程中,15N、18O同位素会因为多种因素而发生分馏,同位素值发生变化使得这种技术的应用存在一定的局限性.本文系统总结了不同来源硝酸盐δ15N、δ18O值的组成特征及其影响因素,分析了在不同土地利用类型流域内,利用硝酸盐15N、18O同位素技术开展硝酸盐来源识别、负荷估算和反硝化作用评估的方法和研究进展.基于已有研究成果,提出在未来的研究过程中,一方面应以流域为单元,选择适当的研究方法并结合多种辅助指标研究多因素共同作用下NO3-污染源的δ15N-NO3-和δ18O-NO3-值的变化规律;另一方面应对比流域污染源详细的调查数据,分析现有负荷估算模型存在的不确定性,并构建合适的负荷计算模型;最后,应深入开展同位素在确定流域和河流中反硝化发生的范围、地点和程度方面的研究,特别是掌握河流系统中沉积物-水体中氮的循环过程. 相似文献
3.
为揭示太湖流域降雨和湖水酸根阴离子长期变化特征及环境意义，通过历史数据收集和采样分析，对太湖流域降雨和湖水中的SO42-、NO3-变化特征和来源进行了研究.结果表明：自1990s以来太湖流域降雨中SO42-呈显著下降趋势，年平均下降率为0.28 mg/（L·a）；NO3-浓度却呈显著上升趋势，年平均增长率为0.05 mg/（L·a），降雨中氮污染呈现加重的趋势.与之相反，湖水中SO42-呈显著上升趋势，年平均增长率为1.24 mg/（L·a）；NO3-浓度却呈显著下降趋势，年平均下降率为0.02 mg/（L·a）.30年以来，太湖水体SO42-/NO3-比值不断升高，远高于降水SO42-/NO3-比值.研究认为：流域SO2排放引起的酸沉降是湖水SO42-浓度增长的最重要原因，但氮氧化物排放并未引起湖水NO3-浓度升高，说明太湖流域对大气沉降的氮氧化物有滞留作用，而太湖水体是流域大气沉降硫酸盐的重要汇.综合治理太湖流域酸性物质排放对防止太湖水体酸化和治理富营养化都具有重要意义. 相似文献
4.
城镇化流域氮、磷污染特征及影响因素——以宁波北仑区小浃江为例 总被引：2，自引：0，他引：2
我国快速的城镇化过程造成了河流氮、磷等营养盐的污染和潜在的水体富营养化问题.对城镇流域水体氮、磷污染特征及其演变趋势的识别具有重要意义.本研究选取长三角典型城镇地区宁波市北仑区小浃江流域为研究对象，在流域内根据空间分布、土地利用类型、人类活动强度等情况布设样点，于2017年夏季和冬季采集水样，研究流域水体氮、磷污染的时空分布特征并分析其污染来源和评估其富营养化水平.结果表明：流域内铵态氮（NH4+-N）、；硝态氮（NO3--N）、亚硝态氮（NO2--N）、总氮（TN）、总磷（TP）和叶绿素a（Chl.a）浓度范围分别为0.63~3.25 mg/L、0.52~3.75 mg/L、0.02~0.22 mg/L、1.61~12.86 mg/L、0.02~0.74 mg/L和0.6~60.57 μg/L.各个采样点氮、磷分布具有较大的空间异质性和季节变化规律.富营养化综合指数EI评估结果显示，整个流域富营养化程度属于贫至中营养级.氮、磷浓度与土地类型面积占比的Spearman相关性统计表明，100 m缓冲区建设用地面积占比与NH4+-N、NO2--N、TN、溶解氧（DO）浓度具有显著相关性，湿地面积占比与DO浓度呈显著正相关.汇水区域内林地面积占比与NH4+-N、NO2--N、TP、PO43--P、COD、Chl.a浓度呈显著负相关，与DO浓度呈显著正相关.相关性分析和冗余分析表明城镇化的面源污染及可能存在的点源污染是小浃江流域氮、磷污染的主要来源.因此，在小浃江流域100 m范围内，控制建设用地的规模和污染排放是减轻流域氮、磷污染的主要途径.在汇水区域内，增加林地植被的面积对减少氮、磷污染具有重要影响. 相似文献
5.
三峡大坝上下游水质时空变化特征 总被引：6，自引：2，他引：4
为探索三峡大坝上下游（坝上99.9 km、坝下63.0 km、全长162.9 km）水质时空变化特征，运用主成分分析和方差分析对2016年近坝段水质时空变化特征进行了分析.主成分分析表明，水文因子流量（Q）、气温（T）、水位（Z）和水质因子（水温（WT）、pH、电导率（EC）、溶解氧（DO）、悬浮物（SS）、高锰酸盐指数（CODMn）、硫酸盐（SO42-）、氟化物（F-）、总硬度（T-Hard）、硝态氮（NO3--N）、总氮（TN）和硒（Se））的变化主导着研究区域水质变化；各采样点主成分得分和双因素方差分析结果显示研究区域水质因子时间变化主要呈现出季节和不同水库运行时期的差异.消落期（2-5月），T-Hard、F-、SO42-和EC是影响河流水质变化的主导因子；汛期（7-8月），Q、SS、CODMn、NO3--N、TN和Se是影响河流水质变化的主导因子；T和WT主导着汛末（9月）河流水质变化，并引起了DO等理化特性的变化；高水位运行期（12月），Cl-是影响河流水质变化的主导因子.现阶段，DO、有机污染物（CODMn）、无机盐（SO42-和F-）、营养盐类（NO3--N和TN）、类金属元素（Se）和水体的矿化程度（T-Hard）的变化主导着区域水质的变化，是三峡大坝近坝段水域水质的控制因子.方差分析表明，河流的理化特性（DO、pH和SS）、营养盐组分构成（NH3-N和NO3--N）、无机盐类（EC和Cl-）、石油类有机污染物及粪大肠菌群（FC）等指标在坝上与坝下断面存在显著性差异.气温、水温、降雨、含沙量的季节性影响因素和水库调度运行模式是影响近坝段水质时间差异的主要因子；空间差异主要受城区污染排放和三峡水库调度引起的坝上和坝下水文和水动力学条件差异影响.因此控制研究区域因人类活动等造成的外源性污染，并针对不同类污染物质的季节变化特征实施合理的水库运行方式是近坝段水质提升的关键. 相似文献
6.
浮游植物对氮的吸收与其生长繁殖密切相关，太湖梅梁湾湖区蓝藻水华频频暴发，对该水域浮游植物氮吸收进行研究具有重要意义.本文分别在冬、春、夏、秋4个季节于梅梁湾采样，对水体常规理化指标和浮游植物群落结构进行分析，并利用15N稳定同位素示踪技术研究了浮游植物对铵态氮（NH4+-N）、硝态氮（NO3--N）和尿素态氮（Urea-N）吸收的动力学特征.结果表明，太湖梅梁湾浮游植物群落除了秋季对NH4+-N的吸收不符合米氏方程外，其余均符合.冬季和春季3种形态氮最大吸收速率（Vmax）的大小依次为：NH4+-N > NO3--N > Urea-N，而夏季为：NH4+-N > Urea-N > NO3--N.3种形态氮Vmax的季节变化规律为夏季 > 秋季 > 春季 > 冬季.Vmax在不同季节以及不同形态氮之间的差异性可能与浮游植物群落组成以及水体中NH4+-N浓度不同有关.浮游植物对NH4+-N吸收的KS值在冬、春季高于夏季，对Urea-N吸收的Ks值则在夏、秋季高于冬、春季，而对NO3--N吸收的Ks值则在夏季显著高于其他3个季节.冬季和春季梅梁湾浮游植物群落最容易受到NO3--N限制，而最不容易受到Urea-N的限制；而夏季，则最容易受到NO3--N限制，而最不容易受到NH4+-N的限制，且浮游植物群落对NH4+-N的亲和力最高.与NO3--N相比，秋季浮游植物更容易受到Urea-N的限制.不同季节，容易对浮游植物产生限制作用的氮的形态不同. 相似文献
7.
湖光岩玛珥湖水体中营养盐的时空分布特征及其影响因素 总被引：1，自引：0，他引：1
湖光岩玛珥湖是世界上最大的玛珥湖，它几乎是封闭的，受外界的干扰小.目前有关玛珥湖的研究主要集中在古气候及生态环境研究方面，而有关玛珥湖营养盐在一年中的生物地球化学循环的研究较少，因此研究湖光岩玛珥湖营养盐的生物地球化学过程具有重要意义.于2015年10月-2016年9月对湖光岩玛珥湖全水柱的营养盐及其他相关参数进行逐月调查，分析营养盐的结构特征、垂直分布特征和时间变化情况，并讨论营养盐时空变化的影响因素.结果表明，湖光岩玛珥湖水中的无机氮（DIN）以铵态氮（NH4+-N）为主（>60%），其次是硝态氧（NO3--N），亚硝态氮（NO2--N）所占比利最低.湖光岩玛珥湖水中的硅酸盐（SiO32--Si）浓度较高，水体浮游植物生长受磷限制.冬季风期间，水体垂直混合较均匀，导致营养盐的垂直分布比较均匀；夏季风期间，水体层化，营养盐浓度在浅层水体较低，在深层水体较高.湖光岩玛珥湖表层水中的NO3--N、NH4+-N和SiO32--Si具有明显的时间变化规律：NO3--N浓度从10月-次年3月升高，从3-9月降低；NH4+-N浓度从10月-次年5月降低；SiO32--Si浓度从11月-次年5月降低，从5-9月持续升高.营养盐浓度的时间变化受有机质的矿化分解、水体的季节性混合、浮游植物的吸收、降雨的输入等多种因素的综合影响. 相似文献
8.
城市湖泊不同水生植被区水体温室气体溶存浓度及其影响因素 总被引：2，自引：1，他引：1
为了解城市湖泊不同水生植被区水体温室气体的溶存浓度及其影响因素，于2015年4-11月按每月2次的频率采用顶空平衡法对聊城市铃铛湖典型植被区——菹草区、莲藕区和睡莲区表层水中CO2、CH4和N2O的溶存浓度进行监测，计算水中温室气体的饱和度和排放通量，并测定水温（T）、pH、溶解氧（DO）、叶绿素a及营养盐浓度等理化指标，以探究水体环境因子对温室气体溶存浓度的影响.结果表明，铃铛湖各植被区水体温室气体均处于过饱和状态，是大气温室气体的"源"；莲藕区CH4浓度、饱和度和排放通量均显著高于菹草区，而各植被区N2O和CO2均无显著性差异；不同植被区湖水中DO、总氮（TN）、总磷（TP）和硝态氮（NO3--N）浓度具有显著差异，其中DO、TN和NO3--N浓度均表现为菹草区最高，莲藕区最低，而TP浓度则正好相反；各植被区温室气体浓度和水环境参数间的相关分析和多元回归分析的结果表明，水生植物可通过影响水体的理化性质对温室气体的产生和排放产生显著差异影响，在菹草区亚硝态氮（NO2--N）、NO3--N、T和DO是控制水体温室气体浓度的主要因子；睡莲区为TP和pH；莲藕区则为pH、NO2--N和DO. 相似文献
9.
生态补水是维持和改善白洋淀生态环境的重要途径.为研究生态补水对白洋淀水环境的影响,分别在补水前与补水后采集淀水、河水及地下水样品,分析区域地表水和地下水水化学特征.结果表明：（1）白洋淀补水前、后地表水与地下水的水化学组成中Na+为主要阳离子,补水后阴离子以HCO3-为主,淀区南部地表水电导率高;补水后地表水与地下水Ca2+、Mg2+和HCO3-浓度显著增加,水体电导率降低.（2）补水前地下水为Na-HCO3型水,地表水主要为Na-Cl·SO4及Na-Cl·HCO3类型;补水后地表水与浅层地下水向Ca·Mg-HCO3型演化,深层地下水水化学类型基本保持不变.（3）生态补水使白洋淀水位升高,淀区水面积增大,缓解了水资源短缺的问题;同时也使浅层地下水水化学组成发生改变,而深层地下水暂未受到影响.生态补水后,受稀释和混合作用的影响,水体Na+、Cl-和SO42-浓度显著下降,Ca2+、Mg2+及HCO3-浓度增加.在白洋淀生态补水中应"先治污,后补水",以减少补水过程中污染物向淀区的运移,还应注意区域地下水位上升过程中的阳离子交换及水岩相互作用,为合理调配生态补水及改善白洋淀生态环境提供科学依据. 相似文献
10.
通过测量辽宁省鞍山-海城地区地震重点监测区地下水离子浓度和氢、氧同位素组成，讨论了该区地下水化学类型的时空变化及其成因。测量结果表明，取样点水温变化范围为11.0～97.0℃，水样的总固溶物（TDS）在197.89～829.99mg/L之间，水样分为8种化学类型。大部分水样的δD、δ18O值均沿中国东北地区大气降水线分布，少数有所偏离，表明该区的地下水主要接受大气降水的补给，并可能有深部水的供给。研究区Ca-HCO3和Ca·Mg-HCO3型水主要是岩石风化溶解和阳离子交换作用的结果；Ca-HCO3·Cl和Ca·Na-Cl·SO4型水主要受岩石风化溶解、阳离子交换作用、深部卤水混入或人类活动影响；Ca-HCO3·SO4和Ca-SO4·HCO3型水与岩石风化溶解以及深部流体混入有关；Na-SO4·HCO3和Na-HCO3·SO4型水主要是深部来源水体的混入造成的。采样期间研究区发生2次ML≥3.0地震，采样点在地震发生月份出现了明显的离子浓度异常变化；Na+、Mg2+、Ca2+、Cl-和SO42-浓度变化明显，对地震活动响应较灵敏。 相似文献
11.
Hydrogeochemical characteristics of surface water and groundwater in the karst basin,southwest China 总被引：1，自引：0，他引：1
Groundwater is a very significant water source used for irrigation and drinking purposes in the karst region, and therefore understanding the hydrogeochemistry of karst water is extremely important. Surface water and groundwater were collected, and major chemical compositions and environmental isotopes in the water were measured in order to reveal the geochemical processes affecting water quality in the Gaoping karst basin, southwest China. Dominated by Ca2+, Mg2+, HCO3? and SO42?, the groundwater is typically characterized by Ca? Mg? HCO3 type in a shallow aquifer, and Ca? Mg? SO4 type in a deeper aquifer. Dissolution of dolomite aquifer with gypsiferous rocks and dedolomitization in karst aquifers are important processes for chemical compositions of water in the study basin, and produce water with increased Mg2+, Ca2+ and SO42? concentrations, and also increased TDS in surface water and groundwater. Mg2+/Ca2+ molar ratios in groundwater decrease slightly due to dedolomitization, while the mixing of discharge of groundwater with high Mg2+/Ca2+ ratios may be responsible for Mg2+/Ca2+ ratios obviously increasing in surface water, and Mg2+/Ca2+ ratios in both surface water and groundwater finally tending to a constant. In combination with environmental isotopic analyses, the major mechanism responsible for the water chemistry and its geochemical evolution in the study basin can be revealed as being mainly from the water–rock interaction in karst aquifers, the agricultural irrigation and its infiltration, the mixing of surface water and groundwater and the water movement along faults and joints in the karst basin. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
12.
Comprehensive studies on the spatial distribution, water quality, recharge source, and hydrochemical evolution of regional groundwater form the foundation of rational utilization of groundwater resources. In this study, we investigated the water levels, hydrochemistry, and stable isotope composition of groundwater in the vicinity of the Qinghai Lake in China to reveal its recharge sources, hydrochemical evolution, and water quality. The level of groundwater relative to the level of water in the Qinghai Lake ranged from −1.27 to 122.91 m, indicating most of the groundwater to be flowing into the lake. The local evaporation line (LEL) of groundwater was simulated as δ2H = 6.08 δ18O-3.01. The groundwater surrounding the Qinghai Lake was primarily recharged through local precipitation at different altitudes. The hydrochemical type of most of the groundwater samples was Ca-Mg-HCO3; the hydrochemistry was primarily controlled by carbonate dissolution during runoff. At several locations, the ionic concentrations in groundwater exceeded the current drinking water standards making it unsuitable for drinking. The main source of nitrate in groundwater surrounding the Qinghai Lake was animal feces and sewage, suggesting that groundwater pollution should be mitigated in areas practicing animal husbandry in the Qinghai-Tibet Plateau, regardless of industrial and urbanization rates being relatively low in the region. The scientific planning, engineering, and management of livestock manure and wastewater discharge from animal husbandry practices is a crucial and is urgently required in the Tibetan Plateau. 相似文献
13.
Abolfazl Rezaei 《Ground water》2021,59(2):236-244
The Sarabkalan Spring serves as a primary water supply to irrigation and domestic use in the Sirvan Region, Iran. As it has a highly variable discharge, understanding its teleconnections with large-scale climate variability is crucial. In this study, we first characterize the springshed and its corresponding karst aquifer system using genetic algorithm analysis on the spring discharge, water balance calculations, temporal variations of physicochemical parameters, and stable isotopes along with considering its geological settings. Then, the large-scale climate indices teleconnections with precipitation and spring discharge are studied using wavelet analysis. Results reveal that the springshed contains two karst subaquifers resulting from geological and morphological settings. Unlike most developed karst systems in Zagros, which show one peak, the spring has two principal flow peaks over most hydrological years where the second peak occurs over the dry season. It takes ∼99 d (from lag correlation over 2008-2019) and ∼145 d (from δ18O measurements over 2018-2019) for rain water to reach the Sarabkalan Spring. Moreover, intense precipitations would result in an increase in discharge and a decrease in electrical conductivity, Ca + Mg, HCO3, SO4, Cl, ionic strength, and δ18O of the spring because of the developed karst conduit(s). It is further found that a positive Pacific Decadal Oscillation phase coupled with El Niño causes an increase in both the precipitation and spring discharge, signifying the influence of the atmospheric circulations of the Pacific Ocean on the spring behavior. 相似文献
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Zaihua Liu Chris Groves Daoxian Yuan Joe Meiman Guanghui Jiang Shiyi He Qiang Li 《水文研究》2004,18(13):2423-2437
High‐resolution measurements of rainfall, water level, pH, conductivity, temperature and carbonate chemistry parameters of groundwater at two adjacent locations within the peak cluster karst of the Guilin Karst Experimental Site in Guangxi Province, China, were made with different types of multiparameter sonde. The data were stored using data loggers recording with 2 min or 15 min resolution. Waters from a large, perennial spring represent the exit for the aquifer's conduit flow, and a nearby well measures water in the conduit‐adjacent, fractured media. During flood pulses, the pH of the conduit flow water rises as the conductivity falls. In contrast, and at the same time, the pH of groundwater in the fractures drops, as conductivity rises. As Ca2+ and HCO3? were the dominant (>90%) ions, we developed linear relationships (both r2 > 0·91) between conductivity and those ions, respectively, and in turn calculated variations in the calcite saturation index (SIC) and CO2 partial pressure (P) of water during flood pulses. Results indicate that the P of fracture water during flood periods is higher than that at lower flows, and its SIC is lower. Simultaneously, P of conduit water during the flood period is lower than that at lower flows, and its SIC also is lower. From these results we conclude that at least two key processes are controlling hydrochemical variations during flood periods: (i) dilution by precipitation and (ii) water–rock–gas interactions. To explain hydrochemical variations in the fracture water, the water–rock–gas interactions may be more important. For example, during flood periods, soil gas with high CO2 concentrations dissolves in water and enters the fracture system, the water, which in turn has become more highly undersaturated, dissolves more limestone, and the conductivity increases. Dilution of rainfall is more important in controlling hydrochemical variations of conduit water, because rainfall with higher pH (in this area apparently owing to interaction with limestone dust in the lower atmosphere) and low conductivity travels through the conduit system rapidly. These results illustrate that to understand the hydrochemical variations in karst systems, considering only water–rock interactions is not sufficient, and the variable effects of CO2 on the system should be evaluated. Consideration of water–rock–gas interactions is thus a must in understanding variations in karst hydrochemistry. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
15.
Yin Long Tianming Huang Fen Zhang Zhenbin Li Baoqiang Ma Yiman Li Zhonghe Pang 《水文研究》2021,35(4):e14166
The use of the sulphate mass balance (SMB) between precipitation and soil water as a supplementary method to estimate the diffuse recharge rate assumes that the sulphate in soil water originated entirely from atmospheric deposition; however, the origin of sulphate in soil and groundwater is often unclear, especially in loess aquifers. This study analysed the sulphur (δ34S-SO4) and oxygen (δ18O-SO4) isotopes of sulphate in precipitation, water-extractable soil water, and shallow groundwater samples and used these data along with hydrochemical data to determine the sources of sulphate in the thick unsaturated zone and groundwater of a loess aquifer. The results suggest that sulphate in groundwater mainly originated from old precipitation. When precipitation percolates through the unsaturated zone to recharge groundwater, sulphates were rarely dissolved due to the formation of CaCO3 film on the surface of sulphate minerals. The water-extractable sulphate in the deep unsaturated zone (>10 m) was mainly derived from the dissolution of evaporite minerals and there was no oxidation of sulphide minerals during the extraction of soil water by elutriating soil samples with deionized water. The water-extractable concentration of SO4 was not representative of the actual SO4 concentration in mobile soil water. Therefore, the recharge rate cannot be estimated by the SMB method using the water-extractable concentration of SO4 in the loess areas. This study is important for identifying sulphate sources and clarifying the proper method for estimating the recharge rate in loess aquifers. 相似文献
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17.
Clay aquitards are semipermeable membranes that allow groundwater flow while retarding solute migration has been researched extensively but also subjected to much debate. At present, there is no evidence of whether the physical and chemical properties of clay soil and the isotopic composition of pore water affect the semipermeable membrane effect. In this study, we collected clay samples from drilling cores (30–90 m) in the Hengshui area located in the North China Plain (NCP), then extracted pore water using a high-pressure squeezing device. Vertical hydrochemical and isotopic profile variation trends for the pore water were revealed using hydrochemical (Cl−, Na+, Ca2+, K+, Mg2+, and SO42−) and stable isotopic measurements of H, O and Cl. The results showed that the hydrochemical clay interlayer pore water of the saline aquifer is Cl/SO4-Na/Mg type and the average total dissolved solids (TDS) are 10.17 g/L. However, the hydrochemical clay aquitard pore water is of the Cl/SO4-Na/Ca type with an average TDS of 1.90 g/L. The hydrochemical clay interlayer pore water of aquifer II is of Cl-Na/Ca type with an average TDS of 1.10 g/L. Our results showed that the water quality of the aquifer II is not affected by the upper part of the saline aquifer, thus the clay aquitard acts as a significant barrier to salt movement. A polarization layer concentrated in ions was formed between the upper part of the saline aquifer and the clay aquitard. The concentration polarization layer increases the salt-inhibition effect. H, O and Cl isotopic composition results showed significant fractionation. The pore water of aquifer II lacked heavy isotopes (2H, 18O, 37Cl), but had significant heavy isotope enrichment in the concentrated polarized layer (the δ2H value was −76‰, the δ18O value was −8.4‰, and the δ37Cl value was 1.59‰). Hyperfiltration thus played a significant role in isotope fractionation. 相似文献
18.
Groundwater salinization has become a crucial environmental problem worldwide and is considered the most widespread form of groundwater contamination in the coastal zone. In this study, a hydrochemical investigation was conducted in the eastern coastal shallow aquifer of Laizhou Bay to identify the hydrochemical characteristics and the salinity of groundwater using ionic ratios, deficit or excess of each ions, saturation indices and factor analysis. The results indicate that groundwater in the study area showed wide ranges and high standard deviations for most of hydrochemical parameters and can be classified into two hydrochemical facies, Ca2+‐Mg2+‐Cl‐ facies and Na+‐Cl‐ facies. The ionic ratio, deficit or excess of each ions and SI were applied to evaluate hydrochemical processes. The results obtained indicate that the salinization processes in the coastal zones were inverse cation exchange, dissolution of calcite and dolomite, and intensive agricultural practices. Factor analysis shows that three factors were determined (Factor 1: TDS, EC, Cl‐, Mg2+, Na+, K+, Ca2+ and SO42‐; Factor 2: HCO3‐ and pH; Factor 3: NO3‐ and pH), representing the signature of seawater intrusion in the coastal zone, weathering of water–soil/rock interaction, and nitrate contamination, respectively. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
19.
The quest for improved water supply to cater for the ever increasing population has given rise to the assessment of water quality and resource potentials in Aba-Urban and its environments. The area, which lies within the Niger Delta Basin is underlain by the Benin Formation that is highly aquiferous. Samples of sands and water were subjected to sedimentological and hydrochemical analysis, respectively. Result reveals that the aquifer is thick (over 100 m) and unconfined. The computed aquifer parameters indicate high yielding clean-sands with hydraulic conductivity values ranging from 1.13 × 10–4 to 5.70 × 10–3 m/s. The specific discharge is about 14.2 m/year while the average linear groundwater velocity is calculated to be 53.46 m/year. Hydrochemical investigations carried out on water samples from Aba River and the groundwater system revealed low dissolved geochemical constituents. Although, there is a slight increase from the north to the southern part along the flow path. In general, the groundwater is relatively enriched in Ca, Mg?HCO-3ions and is predominantly of bicarbonate constituents. However, in some places Cl? ions dominate over HCO-3ions. This is common where the water has come in contact with domestic sewage. This kind of contamination is also accompanied by elevated concentration of NO-3ions. Generally, the groundwater in most cases meets the standard for human consumption and is a better alternative to surface water. Consequently an increase exploitation of the prolific Benin aquifer through more hygienic and safe methods will surely be the best way of improving the domestic water supply situation in Aba City. 相似文献
20.
Using hydrochemical,stable isotope,and river water recharge data to identify groundwater flow paths in a deeply buried karst system 
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下载免费PDF全文 Dajun Qin Zhanfeng Zhao Yi Guo Wencai Liu Muhammed Haji Xiaohong Wang Baodong Xin Yu Li Yong Yang 《水文研究》2017,31(24):4297-4314
The deeply buried river‐connected Xishan karst aquifer (XKA) in western Beijing, China, has been suffering from diminishing recharge for several decades, which in turn leads to the disappearing of spring water outflows and continuously lowering of groundwater level in the area. Thus, it is important to correctly recognize the groundwater recharge and flow paths for the sustainable development of the XKA. To investigate these issues, the hydrochemical and isotopic compositions are analysed for both surface water and groundwater samples collected over an area of about 280 km2. Results show that (a) the river water is characterized by high Na contents; (b) the δ2H and δ18O values in the river water are distinctively higher than those of groundwater samples, after experiencing the long‐time evaporative enrichment in the upstream reservoir; (c) the Sr concentrations and 87Sr/86Sr ratios of groundwater clearly indicated the interaction between water and carbonate minerals but excluded the water–silicate interaction; and (d) the groundwater samples in the direct recharge area of the XKA have the lowest Na concentrations and the δ2H and δ18O values. Based on the large differences in the Na contents and 18O values of groundwater and surface water, a simple two‐component mixing model is developed for the study area and the fractions of the river water are estimated for groundwater samples. We find that the distribution pattern of the river water fractions in the XKA clearly shows a change of directions in the preferential flow path of the groundwater from its source zone to the discharge area. Overall, our results suggest that the recharged surface water can be a useful evidence for delineating the groundwater flow path in river‐connected karst aquifer. This study improves our understanding of the heterogeneity in karst groundwater systems. 相似文献