共查询到18条相似文献，搜索用时 180 毫秒
1.
水体中溶解性有机质(dissolved organic matter, DOM)是含水层中砷释放的主控因素之一.江汉平原河湖众多、沟渠广布,地表水体与浅层地下水的交互作用使得DOM的组分特征及其强度有显著差异.为查明江汉平原地下水中溶解性有机质在砷迁移转化过程中的作用,对江汉平原地表水和浅层地下水进行三维荧光光谱分析,使用平行因子分析法提取水体中有机质的分子组成、功能特点和荧光特征,并分析各组分相对含量与地下水中砷与铁的关联.江汉平原水体中DOM包括3种主要组分,组分C1、C2为类腐殖质,C2是生物降解过程中产生的小分子,C3为类蛋白物质.地下水DOM以类腐殖质组分C1、C2为主,地表水以类蛋白类物质C3和小分子腐殖质C2为主.高砷地下水中DOM以陆源为主,主要通过两种途径促进As的迁移转化:(1) DOM的腐殖质组分充当微生物群落的电子运输工具,促进微生物作用下的有机质氧化和铁氧化物的还原,并伴随As的释放及大量溶解性有机碳(dissolved organic carbon, DOC)和HCO3-的产生;(2) As以铁等金属阳离子为桥接物与腐殖质结合,通过形成As-Fe-DOM络合物,导致地下水中砷的迁移. 相似文献
2.
银川平原属中温带干旱区,蒸发强烈,潜水水质差,承压水是银川市地下水开采的主要水源。通过ArcMap空间分析、传统作图分析、氢氧同位素分析等方法,分析银川地区承压含水层水化学特征及各含水层水化学特征的差异,探讨了承压水水化学分布特征的控制因素。研究表明,潜水和承压水水化学分布特征在水平和垂直方向上均存在较大差异;第一和第二承压水水化学分布特征在水平方向上相似,在垂直方向上存在一定差异。水平方向上,两层承压水水化学特征存在一定分带性,而潜水无明显规律性。两层承压水在靠近西侧补给区溶解性总固体（TDS）较小,阴离子以HCO-3为主,阳离子以Mg2+和Ca2+为主,向东溶解性总固体逐渐增加,在银川断裂附近,阴离子变为以Cl-和SO2-4为主,阳离子以Na+为主。垂向上,由于银川断裂贯穿承压和潜水含水层,且潜水水位高于承压水位,第二承压水可能主要受到更深层地下水沿着断裂的混入作用,第一承压水可能同时受到更深层地下水和潜水的混入,使得在银川断裂附近,部分第二承压水TDS大于第一承压水,且具有更高含量的Na+和Cl-,及更低含量的Ca2+和HCO-3,也有部分第一承压水TDS大于第二承压水,该部分第一承压水中的个别水样TDS大于潜水。由此得出,银川断裂的发育及其对潜水及承压含水层的贯通作用是控制该区地下水水质的一个重要因素。如果承压水继续过量开采,承压水位持续下降,将进一步激发潜水和更深层地下水的混入,从而导致承压水质恶化。因此控制银川区承压水的过量开采,对于承压水资源的可持续利用至关重要。 相似文献
3.
4.
内蒙古土默川平原地下水水文地球化学特征及其成因 总被引：1，自引：0，他引：1
通过水文地质调查、水样采集,结合地下水流动系统、统计分析、吉布斯图、Piper三线图和相关性分析,对土默川平原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,水化学类型以HCO3-Ca型和Cl-Na型为主。潜水水化学成分主要受水-岩相互作用和蒸发浓缩作用影响,承压水水化学成分主要受水-岩相互作用过程控制。79个潜水样品中方解石和白云石饱和指数小于0的分别为1个和5个,56个承压水样品中饱和指数小于0的均为20个。区域地下水的弱碱性环境、高Na+、低Ca2+为高氟水的形成提供了条件,受蒸发浓缩作用影响潜水高氟区主要分布于托克托县城以东地下水的滞留排泄区;受含水层介质的影响承压水高氟区主要分布于湖积台地区域。局部区域地下水的强还原环境,铁、锰氧化物和氢氧化物的还原性溶解以及HCO–3的竞争吸附是形成高砷水的重要原因,受哈素海湖相沉积物的影响潜水高砷区主要分布在哈素海—高泉营一带;受铁氧化物、氢氧化物还原性溶解及地下水径流条件的控制,承压水高砷区主要分布在平原中部大黑河沿岸。 相似文献
5.
为了认识高砷地下水中砷活化迁移的生物地球化学机制,对江汉平原地下水氧化还原敏感元素的水化学特征及溶解性有机物(DOM)三维荧光信息进行了研究.水化学研究显示,地下水中的砷与铁的还原和有机质的氧化分解过程有密切关系.水样DOM的三维荧光分析表明,地下水中存在微生物介导下氧化还原过程的反应性有机物组分,其中醌类腐殖质与铁、硫酸盐等的还原反应过程联系紧密.还原、氧化醌类及易降解DOM组分与还原产物、砷的关系进一步显示,砷的活化与微生物介导下的铁氧化物的还原过程联系在一起.在这一过程中,易降解有机物充当电子供体的角色并被消耗,而还原醌与氧化醌则很可能扮演了电子飞行过程中的电子飞行物,"催化"了砷活化的氧化还原过程. 相似文献
6.
吉林省饮水型砷中毒区是继中国内蒙古和山西病区后发现的新病区。该病区主要分布在吉林省西部的通榆县和洮南市,其水文地质单元属于松嫩平原大型蓄水盆地的西部,是由第四系潜水、承压水和新近系承压水组成的多层结构的含水系统。采用瞬时采样法采集了区内潜水和承压水样品,共194份;通过GIS的空间叠加技术、化验与测试技术,进行了区域水化学环境特征与饮水型砷中毒的关系研究。结果表明：受区域地质构造控制,在低洼地带堆积了巨厚的粉砂淤泥质冲积物和富含有机质的湖积物,为地下水砷的赋存提供了空间。区域地下水砷含量的范围值为0.001~0.339 mg·L-1,水砷价态以As(V)为主,高砷水主要分布在由若干隆起形成的中间低洼地带中地下水埋深大于10 m的潜水、第四系和新近系承压水含水层中。高砷地下水的形成与特定的水文地质条件和水化学环境有关,氯化物重碳酸钠型水中的砷含量最高。臭葱石（FeAsO4·2H2O）等含铁、含锰矿物在进入地下水的溶解过程中,形成铁、锰的氧化物和砷的化合物,如砷酸盐和亚砷酸盐。伴随着水环境中Eh的降低,氧化物被还原形成更为活泼的离子组分,吸附在氧化物表面的含砷化合物进而解吸,使砷从含水层的沉积物中向水中溶解和迁移。 相似文献
7.
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
8.
扬-泰-靖地区地下水系统水力联系与硫酸盐污染特征 总被引：2，自引：0，他引：2
本文对长江三角洲扬-泰-靖地区第四系松散层地下水中环境同位素(D、18O、34S)的分布特征进行了分析,旨在揭示大气降水、长江水、潜水及承压水之间的水力联系,辨别地下水中硫酸盐的来源及其污染状况。研究结果表明潜水含水层接受大气降水及长江水的补给,硫酸盐主要为农业污染来源或与海源硫酸盐的混合。承压含水层主要接受大气降水的补给,与潜水含水层及长江之间的水力联系较差,硫酸盐来源不同。在研究区顶部和沿江地段的浅层孔隙承压水中,硫酸盐来源于硫化物的氧化;在东部的深层孔隙承压水中,硫酸盐主要来源于硫酸盐岩的溶解或海源硫酸盐的滞留,基本未受到潜水或地表水中硫酸盐的污染。 相似文献
9.
含水层中有机物对地下水水质的影响 总被引：1，自引：0，他引：1
化学热动力学和稳定碳同位素[δ(13C)]的研究表明浅层地下水中的碳源是地下含水层中有机物淋溶和降解作用的结果.根据天然有机物的降解规律以及CO2在水中的溶解平衡,采用CO2分压[p(CO2)]来表征有机物的影响,通过计算p(CO2)与地下水中部分化学指标的相关关系,讨论了有机物对地下水化学性质的影响.结果表明地下含水层中有机物的增加会导致地下水酸度的增大以及HCO-3、Na 和F-等质量浓度的增大;且由于地层中有机物含量较高,导致地下水中含氮物质总量升高,同时,由于大量有机物的存在而导致地下水处于还原性环境,促使地下水的氮组分更多地以NO-2-N的形式存在. 相似文献
10.
查明地下水中砷的时间变异性规律及机理是高砷地下水研究的难点和热点, 也是防控地下水砷污染的根本.选择在雨季前后对浅层潜水和孔隙承压水进行了动态监测.研究表明地下水砷含量和形态与地下水位波动存在明显的响应关系: 雨季开始后随着地下水位抬升, 地下水还原环境增强, As(Ⅴ)和Asp转化成As(Ⅲ), 颗粒态铁大幅降低, 导致水中溶解的砷和铁大幅增加, 地下水砷含量在雨季达到最高且As(Ⅲ)所占比例达到90%;雨季结束后随着水位逐渐降低, 地下水中As(Ⅲ)所占比例和溶解的砷含量下降.农业活动对浅层潜水砷形态季节性变化有明显的影响.孔隙承压水的砷形态分布变化较浅层潜水幅度大, 其变化与水位波动存在滞后效应.自然或人为活动引起的地下水位季节性变化改变了含水层的氧化还原环境, 补给水源与地下水之间的混合过程带来新的物质输入促进地下水系统中砷的迁移转化. 相似文献
11.
Xianjun Xie Yanxin WangChunli Su Huaiqing LiuMengyu Duan Zuoming Xie 《Journal of Geochemical Exploration》2008
To better understand the sources and mobilization processes responsible for arsenic enrichment in groundwater in the central part of Datong Basin where serious arsenic poisoning cases have been reported, hydrochemical characteristics of the groundwater and the geochemical and mineralogical features of the aquifer sediments were studied. The aqueous arsenic levels are strongly depth-dependent in the study area and the high arsenic concentrations are found at depths between 15 m and 60 m, with a maximum up to 1820 μg/L. The hydrochemical characteristics of high arsenic groundwater from the Datong Basin indicate that the mobilization of arsenic is related to reductive dissolution of Fe oxides/oxyhydroxides and/or desorption from the Fe oxides/oxyhydroxides at high pH (above 8.0). The bulk chemical results of sediments show the arsenic and iron are moderately correlated, suggesting that arsenic is associated with iron-bearing minerals. Results of sequential-extraction experiment show that solid-phase arsenic is similarly distributed among the different pools of reservoir in the aquifer sediments. Strongly adsorbed arsenic and co-precipitated arsenic are its dominant species in the solid-phase. Geochemical studies using chemical analysis, X-ray diffraction and scanning electron microscopy on magnetically separated fractions demonstrate that iron oxides/oxyhydroxides with residual magnetite and chlorite, illite, iron oxides/oxyhydroxides-coated quartz and feldspar, and ankerite are the dominant carriers of arsenic in the sediments. The major processes of arsenic mobilization are probably linked to desorption of As from Fe oxides/oxyhydroxides and reductive dissolution of Fe-rich phases in the aquifer sediments under reducing and alkaline conditions. 相似文献
12.
Arsenic concentrations surpassing potability limit of 10 μg/L in the groundwater supplies of an extensive area in the Duero Cenozoic Basin (central Spain) have been detected and the main sources of arsenic identified. Arsenic in 514 samples of groundwater, having mean values of 40.8 μg/L, is natural in origin. Geochemical analysis of 553 rock samples, assaying arsenic mean values of 23 mg/kg, was performed. Spatial coincidence between the arsenic anomaly in groundwater and the arsenic lithogeochemical distribution recorded in the Middle Miocene clayey organic-rich Zaratan facies illustrates that the rocks of this unit are the main source of arsenic in groundwater. The ferricretes associated to the Late Cretaceous–Middle Miocene siliciclastics also constitute a potential arsenic source. Mineralogical study has identified the presence of arsenic in iron oxides, authigenic pyrite, manganese oxides, inherited titanium–iron oxides, phyllosilicates and organomineral compounds. Arsenic mobilization to groundwater corresponds to arsenic desorption from iron and manganese oxides and from organic matter. 相似文献
13.
为了解包气带土壤DOM组成特征, 探索其对砷向地下水中迁移的影响, 对江汉平原高砷区土壤DOM进行了三维荧光光谱分析.结果表明DOM主要为类腐殖质成分, 芳香性官能团的减少导致荧光强度随包气带深度增加而变小, 局部深度荧光信号不规则变化指示非均质土壤剖面上DOM组分或主导官能团的变化.平行因子分析表明, DOM组分可更细致地分解为4种组分, 与微生物源的还原、氧化醌类和陆生的腐殖质富里酸类等相似.砷很可能在DOM腐殖质成分络合作用下与之随水体一起向下迁移, 砷的迁移也可能与微生物源的醌类作用过程有关.三维荧光光谱分析准确、快速地刻画了包气带土壤DOM的组分类别及空间变化特征, 初步揭示了DOM影响砷迁移的可能作用方式, 为进一步的地下水砷污染机制的研究提供了重要的参考信息. 相似文献
14.
宁夏银川平原是继河套平原之后,在黄河流域发现的又一个高砷地下水分布区.为了总结其高砷地下水的水化学特征,并探索水化学因素对地下水砷释放和富集的影响机制,本文以银川平原北部（银北平原）作为典型研究区,采取野外水文地质调查、水样采集与测试、砷与水化学组分散点图相关分析及水文地球化学方法进行了综合研究.结果表明,银北平原地下水砷含量在0.2~177 μg/L之间;高砷地下水（大于50 μg/L） pH值多在7.5~8.5,水化学类型主要为HCO3-Na·Ca、Cl·HCO3-Na及Cl·HCO3-Na·Ca型,Eh多在-200~-100 mV.银北平原砷含量较高的地下水中COD、NH4+、HCO3-含量相应也较高,而NO3-和SO42-含量较低.高砷富有机质的冲-湖积含水层经过长期演化,形成偏碱性的中强还原性地下水环境和特殊的水化学特征,也具备极大的砷释放能力.较高的pH导致砷从铁锰氧化物或氢氧化物等水合物或黏土矿物表面解吸.其次部分铁锰氧化物在高pH、低Eh条件下可被还原为低价态可溶性铁锰,从而使与其结合的砷也得以释放进入地下水中.此外重碳酸根与砷酸根、亚砷酸根的竞争吸附行为促使含水层砷的解吸. 相似文献
15.
高砷地下水研究的热点及发展趋势 总被引：4，自引：0，他引：4
全球范围内广泛分布的高砷地下水给人们的健康造成了极大的威胁.高砷地下水的形成机理是一项世界性的科学问题.介绍了高砷地下水的分布特点、富集机理,阐明了溶解性有机物、地下水流动特征对高砷地下水形成的影响机制.现今的研究揭示了有机物和微生物协同作用下高砷地下水的形成过程,并且在高砷地下水的空间分布、时间变化特征以及人类活动对高砷地下水形成的影响等方面取得了一些创新性成果.这3方面的研究也逐渐成为近些年高砷地下水研究的热点.这些研究不仅丰富了砷迁移转化的理论成果,而且有助于开辟低砷水源,保障水资源的可持续利用,具有重要的理论和现实意义. 相似文献
16.
Jaya K. Gurung Hiroaki Ishiga Mohan S. Khadka Nav R. Shrestha 《Environmental Geology》2007,52(3):503-517
The geochemical analyses of fluvial-lacustrine aquifer sediments of the Kathmandu Valley have been made as a step in assessing
the environment for the mobilization of arsenic in groundwater. Elements measured by X-ray fluorescence (XRF) include 4 major
oxides (Fe2O3, TiO2, CaO, P2O5) and 14 trace elements (As, Pb, Zn, Cu, Ni, Cr, V, Sr, Y, Nb, Zr, Th, Sc and TS). Elution tests of 15 selected core samples
were also carried out to determine the potential leaching of arsenic from the sediments. The XRF results show that average
bulk concentrations of the major oxides and trace elements are similar to modern unconsolidated sediments and average upper
continental crust. However, the abundance of elements varies with grain size, with higher concentrations in finer-size grades.
Variations in elemental abundances within the basin are strongly controlled by sediment facies. The elution tests show that
greater amounts of arsenic are generally eluted from the fine sediments, although the rates are variable. The results overall
suggest that As concentrations in the bulk sediments are not a controlling factor for elevated As in the Kathmandu Basin groundwater,
and the roles of other factors such as redox conditions and organic matter contents are likely to be more significant. 相似文献
17.
Arsenic associations in sediments from shallow aquifers of northwestern Hetao Basin,Inner Mongolia 总被引：1，自引：0，他引：1
Understanding the mechanism of arsenic mobilization from sediments to groundwater is important for water quality management
in areas of endemic arsenic poisoning, such as the Hetao Basin in Inner Mongolia, northern China. Aquifer geochemistry was
characterized at three field sites (SH, HF, TYS) in Hangjinhouqi County of northwestern Hetao Basin. The results of bulk geochemistry
analysis of sediment samples indicated that total As concentrations have a range of 6.8–58.5 mg/kg, with a median of 14.4 mg/kg.
The highest As concentrations were found at 15–25 m depth. In the meanwhile, the range of As concentration in the sediments
from background borehole is 3–21.8 mg/kg, with a median value of 9 mg/kg. The As sediments concentrations with depth from
the SH borehole were correlated with the contents of Fe, Sb, B, V, total C and total S. Generally, the abundance of elements
varied with grain size, with higher concentrations in finer fractions of the sediments. Distinct lithology profile and different
geochemical characteristics of aquifer sediments indicate the sediments are associated with different sources and diverse
sedimentary environments. Up to one third of arsenic in the sediments could be extracted by ammonium oxalate, suggesting that
Fe oxyhydroxides may be the major sink of As in the aquifer. Sequential extraction results indicate that arsenic occurs as
strongly adsorbed on and/or co-precipitated with amorphous Fe oxyhydroxides in sediments accounting for 35 and 20%, respectively,
of the total contents of arsenic. The release of As into groundwater may occur by desorption from the mineral surface driven
by reductive dissolution of the Fe oxide minerals. Furthermore, small proportions of As associated with iron sulfides occur
in the reductive sediments. 相似文献
18.
Hydrogeochemistry and arsenic contamination of groundwater in the Rayen area, southeastern Iran 总被引：1，自引：1，他引：0
High As contents in groundwater were found in Rayen area and chosen for a detailed hydrogeochemical study. A total of 121 groundwater samples were collected from existing tube wells in the study areas in January 2012 and analyzed. Hydrogeochemical data of samples suggested that the groundwater is mostly Na–Cl type; also nearly 25.62 % of samples have arsenic concentrations above WHO permissible value (10 μg/l) for drinking waters with maximum concentration of aqueous arsenic up to 25,000 μg/l. The reducing conditions prevailing in the area and high arsenic concentration correlated with high bicarbonate and pH. Results show that arsenic is released into groundwater by two major phenomena: (1) through reduction of arsenic-bearing iron oxides/oxyhydroxides and Fe may be precipitated as iron sulfide when anoxic conditions prevail in the aquifer sediments and (2) transferring of As into the water system during water–acidic volcanic rock interactions. 相似文献