黄河小浪底水库水沙调控与流域硫循环

陆地风化的硫酸盐(SO42?)通过河流体系输入海洋,其通量以及硫酸盐同位素组成(δ34SSO4和 δ18OSO4)对全球硫循环及海洋SO42?同位素组成至关重要.河流体系SO42?含量及δ34SSO4和δ18OSO4组成不但受SO42?来源控制,而且受河流内部硫酸盐细菌还原及氧化过程影响,但其影响程度仍不明确,特别是拦...     

河北平原地下水硫酸盐34S和18O同位素演化特征

地下水中硫酸盐的34Ss和18O在探寻地下水的水质演化规律、赋存环境特征方面具有重要的研究意义,笔者选取保定-河间-沧州-黄骅剖面采集深层地下水水样,分析测试了其主要阴阳离子含量、δ18O、δD、14C及δ34Sso42-和δ18Oso42-各项指标,在此基础上首次探讨了河北平原地下水中硫酸盐的硫、氧同位素分布特征与演化机理.研究发现研究区地下水硫酸盐的δ34Sso42-值沿地下水流向增大,δ18Oso42-值则在一个较小的范围内波动,最终接近一个常数值,二者间呈现较好的负相关关系;δ34Sso42-值随地下水14C年龄的增加而增加,δ34Sso42-则随地下水14C年龄的增加而趋于稳定;34Sso42-值与r(so42-)/r(C1-)的值呈负相关关系,δ18Oso42-值与r(SO42-)/r(C1-)的值则呈正相关关系.在研究区地下水中硫酸盐的34S和18O同位素的分布演变特征主要由SO42-和水之间的同位素交换反应、微生物硫酸盐的还原作用、硫化氢的再氧化作用所影响,其中微生物硫酸盐的还原作用的结果使地下水中的硫酸盐富集34S,SO42-和水之间的同位素交换反应是影响地下水的δ18Oso42-值的主导因素,使地下水的δ18Oso42-取决于地下水的氧同位素组成.     

硫酸盐中三氧同位素研究进展

氧同位素组成是一个非常有效的示踪硫酸盐的起源和形成环境的工具.过去主要针对硫酸盐中的氧同位素δ(18O)的研究,近年来,随着硫酸盐中氧同位素质量不相关分馏现象的陆续发现,其δ(17O)的研究成为热点与前沿.在综述了硫酸盐三氧同位素测试技术的研究现状及进展情况后,重点介绍了从硫酸盐中直接提取O2供质谱计同时测定δ(17O)与δ(18O)值的CO2-激光氟化法;同时介绍了硫酸盐中氧同位素异常[Δ(17O)]的研究历程,探讨了硫酸盐中氧同位素质量不相关分馏的机理及三氧同位素的应用前景,展望了今后的研究趋势.     

硫酸盐三氧同位素测试制样新技术——Ag2SO4热解法

氧同位素能有效地示踪硫酸盐起源及其形成环境,随着硫酸盐中氧同位素质量不相关分馏现象的陆续发现,三氧同位素的研究已成为热点与前沿.笔者研究了硫酸盐三氧同位素(16O、17O、18O)测试制样的最新技术--Ag2SO4热解法.基本原理是:Ag2SO4在1050℃下热解为O2和SO2,其中O2产额可达(45±7)%,SO2产额接近100%,收集两种气体送作质谱分析可测得δ17O、δ18O和δ34S值.本方法的特殊要求是所有硫酸盐样品都必须转化为Ag2SO4,笔者详细介绍了水样、土样、石膏样品、BaSO4样品的处理方法与步骤.Ag2SO4热解法不再使用传统方法中的氟化试剂,安全可靠、价廉,顺应了环保意识和以人为本的原则.技术先进:适用性强,具有很大的推广应用价值.     

碳酸盐岩中微量硫酸盐的氧硫同位素分析

 从碳酸盐岩中定量提取SO₄^2-是分析碳酸盐岩中微量硫酸盐氧、硫同位素组成的一个关键问题。在提取过程中要求不发生明显的同位素分馏。提取出的硫酸盐最终以硫酸钡形式沉淀出来。测定此硫酸钡的氧、硫同位素组成便获相关碳酸盐岩中微量硫酸盐δ¹⁸O的及δ³⁴S值。     

黔中茶店桥地下河流域不同水体硫酸盐浓度特征及来源识别

茶店桥地下河位于西南岩溶区,流域内"三水"转换迅速,地下水是当地的重要饮用水源。本文对流域内雨水、地表水、地下水中的SO_4~(2-)浓度进行了测试,利用氘(δD_(H_2O))、氧(δ~(18) O_(H_2O))同位素示踪地表水、地下水补给来源,用硫酸盐硫(δ~(34)S_(SO4))、氧(δ~(18) O_(SO4))同位素探讨了地表水、地下水中SO_4~(2-)的来源,并计算了地下河出口河水中不同SO_4~(2-)来源的贡献比例。结果表明:1不同水体中SO_4~(2-)浓度大小顺序为地表水地下水雨水,与邻近区域相比,茶店桥地下河流域雨水、地表水、地下水呈现富集SO_4~(2-)的特征。2地表水、地下水的主要补给来源为大气降水,硫酸不仅和HCO_3~-共同参与了流域内碳酸盐岩的溶解,也参与了雨水中含钙镁颗粒物的溶解。3地表水δ~(34)S_(SO4)、δ~(18) O_(SO4)值分别介于-12.98‰~-10.19‰和-0.54‰~+9.13‰之间,地下水δ~(34)S_(SO4)、δ~(18) O_(SO4)值分别介于-14.32‰~+16.58‰和+2.81‰~+14.35‰之间,SW02的SO_4~(2-)主要来源于大气降水,SW01、SW03、GW02、GW03、GW06主要来源于煤层,GW05主要来源于石膏,GW01、GW04为混合输入源。4地下河出口河水中大气降水带来的SO_4~(2-)贡献比例为13%,煤层硫化物氧化的贡献比例为40%,石膏溶解的贡献比例为47%。     

长江干流丰水期河水硫酸盐同位素组成特征及其来源解析

碳酸盐岩的硫酸风化机制及其与碳循环的关系是全球碳循环研究中最为关注的科学问题之一, 其关键问题是识别硫酸盐来源.通过分析长江干流丰水期SO₄2-浓度及其硫、氧同位素组成特征, 探讨长江硫酸盐的来源及其主要控制因素.长江河水SO₄2-含量呈现逐年增加的趋势, 并且年增幅度逐渐加大.δ34S_SO4和δ18O_SO4变化范围为-3.5‰~5.6‰和3.7‰~9.2‰, 二者呈现显著的线性负相关关系.δ18O_SO4值从上游到下游的增加趋势受长江水δ18O_H2O值的空间组成特征的影响.研究表明, 大气降水(酸雨)和硫化物氧化是控制长江干流丰水期河水硫、氧同位素组成及其来源的主要机制, 为研究长江流域化学风化侵蚀作用和碳循环过程提供重要的理论依据.      

喀什平原区地下水氢氧稳定同位素分布特征及意义

为系统研究喀什平原区第四系孔隙水补、径、排条件,搞清地下水资源量和供水潜力,在充分了解水文地质条件基础上,采用对比分析方法,分析喀什平原区地下水稳定同位素(D、~(18)O)特征。研究表明,区内地下水补给主要来自大气降水,部分较低的D、~(18)O同位素组成来自山区贫重同位素冰雪融水及基岩裂隙水的补给。山前冲洪积平原潜水和冲积细土平原承压水分属不同地下水流系统。南部盖孜河地下水多来源于西昆仑高山区,细土平原区部分地下水来源于南部中低山丘陵区。研究区北部克孜勒河地下水来源于西南天山。     

硫酸盐的氧同位素测量方法

硫酸盐不仅是常见矿物,还是自然界少数几个具有氧同位素非质量分馏效应的矿物之一。硫酸盐矿物的氧同位素组成,特别是硫酸盐的氧同位素非质量分馏效应,可以为研究其形成过程和条件提供大碹有用信息,揭示一些元素浓度甚至单个同位素比值测量无法获得的特殊作用过程。但由于硫酸盐的氧同位素分析技术难度大,这一方法在国内尚未建立起来。论文介绍了BrF5法测量硫酸盐氧同位素组成的实验装置、分析流程和测量结果。该方法是目前唯一可以同时测量硫酸盐^17O／^16O和^18O／^16O比值的方法。对BaSO4国际氧同位素标准样品NBS-127和一种BaSO4化学试剂进行了多次重复测量。测量的NBS-127国际标样的δ^18Ov-SMOW=（9．20±0．11）‰,与标准值完全一致;BaSO4化学试剂的δ^18Ov-SMOW=（14．64±0．13）‰。分析精度（标准偏差）达到0．13％。（1σ）,优于国外（0．15～0．29）‰（1σ）的水平     

内蒙古额济纳盆地硫酸盐沉积物中δ17O异常及其指示意义

为探析我国干旱地区地表硫酸盐沉积物中δ17O异常的存在及其变化特征,在西北额济纳盆地采集地表盐结层、现代风尘土、湖底沉积物和盐池土壤四种不同类型的硫酸盐沉积物样品。利用硫酸银(Ag2SO4)热解法同时测定硫酸盐样品中的δ17O和δ18O值,其δ17O、δ18O和Δ17O的分析精度分别为0.5‰、0.3‰和0.1‰。研究发现:(1)四种不同硫酸盐沉积物中均存在δ17O异常,其Δ17O值为0.2‰~1.0‰,这表明具有δ17O异常的硫酸盐能够从大气圈转移到陆壳矿物中,并在特定的地表环境中累积起来;(2)西戈壁的吉格德查盐池土壤剖面上硫酸盐Δ17O值随深度增加而增大,变化范围为0‰~0.6‰,这可能是干旱区极其有限的降水淋滤作用使具有较大Δ17O值的硫酸盐优先淋滤的结果,这种分离效应揭示的是在干旱的气候条件下,硫酸盐在土壤剖面上分离的过程。本研究证明我国干旱沉积环境中的硫酸盐δ17O异常的存在,为大气中臭氧(O3)和过氧化氢(H2O2)的氧同位素异常能够转移到地表矿物中提供新的证据,为地表沉积物中硫酸盐的来源、迁移、混合及沉积后的变化提供有效信息。     

Groundwater mixing and mineralization processes in a mountain–oasis–desert basin,northwest China: hydrogeochemistry and environmental tracer indicators

Hydrogeochemistry and environmental tracers (²H, ¹⁸O, ⁸⁷Sr/⁸⁶Sr) in precipitation, river and reservoir water, and groundwater have been used to determine groundwater recharge sources, and to identify mixing characteristics and mineralization processes in the Manas River Basin (MRB), which is a typical mountain–oasis–desert ecosystem in arid northwest China. The oasis component is artificial (irrigation). Groundwater with enriched stable isotope content originates from local precipitation and surface-water leakage in the piedmont alluvial–oasis plain. Groundwater with more depleted isotopes in the north oasis plain and desert is recharged by lateral flow from the adjacent mountains, for which recharge is associated with high altitude and/or paleo-water infiltrating during a period of much colder climate. Little evaporation and isotope exchange between groundwater and rock and soil minerals occurred in the mountain, piedmont and oasis plain. Groundwater δ²H and δ¹⁸O values show more homogeneous values along the groundwater flow direction and with well depths, indicating inter-aquifer mixing processes. A regional contrast of groundwater allows the ⁸⁷Sr/⁸⁶Sr ratios and δ¹⁸O values to be useful in a combination with Cl, Na, Mg, Ca and Sr concentrations to distinguish the groundwater mixing characteristics. Two main processes are identified: groundwater lateral-flow mixing and river leakage in the piedmont alluvial–oasis plain, and vertical mixing in the north oasis plain and the desert. The ⁸⁷Sr/⁸⁶Sr ratios and selected ion ratios reveal that carbonate dissolution and mixing with silicate from the southern mountain area are primarily controlling the strontium isotope hydrogeochemistry.     

松嫩平原地下水流动模式的环境同位素标记

采用同位素水文学方法并结合传统水文地质方法,识别松嫩平原地下水流动模式。氢氧稳定同位素和地下水年龄分布表明该区地下水流动系统流动模式呈现出局部流、中间流和区域流系统。地下水中氚分布深度指示局部水流系统为现代水循环系统,以垂向运动为主要特征,循环深度一般小于50 m,山前区可达100m以下;区域流系统存在于深部承压含水层,以侧向水平径流为主要运动特征。松辽边界附近的环境同位素特征存在明显的差别,指示天然状态下可视为零通量边界。同位素示踪剂也反映出嫩江和地下水的相互作用关系,在齐齐哈尔以北,江水补给地下水;在齐齐哈尔以南,地下水向嫩江排泄。     

Hydrogeochemical and isotopic evidence of groundwater evolution and recharge in aquifers in Beijing Plain, China

An investigation was conducted in Beijing to identify the groundwater evolution and recharge in the quaternary aquifers. Water samples were collected from precipitation, rivers, wells, and springs for hydrochemical and isotopic measurements. The recharge and the origin of groundwater and its residence time were further studied. The groundwater in the upper aquifer is characterized by Ca-Mg-HCO₃ type in the upstream area and Na-HCO₃ type in the downstream area of the groundwater flow field. The groundwater in the lower aquifer is mainly characterized by Ca-Mg-HCO₃ type in the upstream area and Ca-Na-Mg-HCO₃ and Na-Ca-Mg-HCO₃ type in the downstream area. The δD and δ¹⁸O in precipitation are linearly correlated, which is similar to WMWL. The δD and δ¹⁸O values of river, well and spring water are within the same ranges as those found in the alluvial fan zone, and lay slightly above or below LMWL. The δD and δ¹⁸O values have a decreasing trend generally following the precipitation → surface water → shallow groundwater → spring water → deep groundwater direction. There is evidence of enrichment of heavy isotopes in groundwater due to evaporation. Tritium values of unconfined groundwater give evidence for ongoing recharge in modern times with mean residence times <50 a. It shows a clear renewal evolution along the groundwater flow paths and represents modern recharge locally from precipitation and surface water to the shallow aquifers (<150 m). In contrast, according to ¹⁴C ages in the confined aquifers and residence time of groundwater flow lines, the deep groundwater is approximately or older than 10 ka, and was recharged during a period when the climate was wetter and colder mainly from the piedmont surrounding the plain. The groundwater exploitation is considered to be “mined unsustainably” because more water is withdrawn than it is replenished.     

Identifying the recharge sources and age of groundwater in the Songnen Plain (Northeast China) using environmental isotopes

The recharge sources and groundwater age in the Songnen Plain, Northeast China, were confirmed using environmental isotopes. The isotopic signatures of the unconfined aquifers in the southeast elevated plain and the north and west piedmont, cluster along local meteoric water lines (LMWLs) with a slope of about 5. The signature of source water was obtained by the intersection of these LMWLs with the regional meteoric water line (RMWL). This finding provides evidence that the recharge water for these areas originate from the Changbai Mountains and the Low and High Hingan Mountains, respectively. Groundwater in the unconfined aquifer in the low plain yields a LMWL with a slope of 4.4; its nitrate concentration indicates the admixture of irrigation return flow. The δ-values of the unconfined aquifer in the east elevated plain plot along the RMWL, reflecting recharge by local precipitation. The mean residence time of groundwater in these aquifers is less than 50?years. However, the ¹⁴C age of the groundwater in the confined Quaternary aquifer ranges from modern to 19,500?years, and in the Tertiary confined aquifer from 3,100 to 24,900?years. Modern groundwater is mainly recharged to the Quaternary confined aquifer on the piedmont by local precipitation and lateral subsurface flow.     

Environmental isotopic study on the recharge and residence time of groundwater in the Heihe River Basin, northwestern China

The recharge and origin of groundwater and its residence time were studied using environmental isotopic measurements in samples from the Heihe River Basin, China. δ¹⁸O and δD values of both river water and groundwater were within the same ranges as those found in the alluvial fan zone, and lay slightly above the local meteoric water line (δD=6.87δ¹⁸O+3.54). This finding indicated that mountain rivers substantially and rapidly contribute to the water resources in the southern and northern sub-basins. δ¹⁸O and δD values of groundwater in the unconfined aquifers of these sub-basins were close to each other. There was evidence of enrichment of heavy isotopes in groundwater due to evaporation. The most pronounced increase in the δ¹⁸O value occurred in agricultural areas, reflecting the admixture of irrigation return flow. Tritium results in groundwater samples from the unconfined aquifers gave evidence for ongoing recharge, with mean residence times of: less than 36 years in the alluvial fan zone; about 12–16 years in agricultural areas; and about 26 years in the Ejina oasis. In contrast, groundwater in the confined aquifers had ¹⁴C ages between 0 and 10 ka BP.     

Groundwater recharge and salinization in the arid coastal plain aquifer of the Wadi Watir delta,Sinai, Egypt

The Quaternary coastal plain aquifer down gradient of the Wadi Watir catchment is the main source of potable groundwater in the arid region of south Sinai, Egypt. The scarcity of rainfall over the last decade, combined with high groundwater pumping rates, have resulted in water-quality degradation in the main well field and in wells along the coast. Understanding the sources of groundwater salinization and amount of average annual recharge is critical for developing sustainable groundwater management strategies for the long-term prevention of groundwater quality deterioration. A combination of geochemistry, conservative ions (Cl and Br), and isotopic tracers (^87/86Sr, δ⁸¹Br, δ³⁷Cl), in conjunction with groundwater modeling, is an effective method to assess and manage groundwater resources in the Wadi Watir delta aquifers. High groundwater salinity, including high Cl and Br concentrations, is recorded inland in the deep drilled wells located in the main well field and in wells along the coast. The range of Cl/Br ratios for shallow and deep groundwaters in the delta (∼50–97) fall between the end member values of the recharge water that comes from the up gradient watershed, and evaporated seawater of marine origin, which is significantly different than the ratio in modern seawater (228). The ^87/86Sr and δ⁸¹Br isotopic values were higher in the recharge water (0.70,723 < ^87/86Sr < 0.70,894, +0.94 < δ⁸¹Br < +1.28‰), and lower in the deep groundwater (0.70,698 < ^87/86Sr < 0.70,705, +0.22‰ < δ⁸¹Br < +0.41‰). The δ³⁷Cl isotopic values were lower in the recharge water (−0.48 < δ³⁷Cl < −0.06‰) and higher in the deep groundwater (−0.01 < δ³⁷Cl < +0.22‰). The isotopic values of strontium, chloride, and bromide in groundwater from the Wadi Watir delta aquifers indicate that the main groundwater recharge source comes from the up gradient catchment along the main stream channel entering the delta. The solute-weighted mass balance mixing models show that groundwater in the main well field contains 4–10% deep saline groundwater, and groundwater in some wells along the coast contain 2–6% seawater and 18–29% deep saline groundwater.A three-dimensional, variable-density, flow-and-transport SEAWAT model was developed using groundwater isotopes (⁸⁷Sr/⁸⁶Sr, δ³⁷Cl and δ⁸¹Br) and calibrated using historical records of groundwater level and salinity. δ¹⁸O was used to normalize the evaporative effect on shallow groundwater salinity for model calibration. The model shows how groundwater salinity and hydrologic data can be used in SEAWAT to understand recharge mechanisms, estimate groundwater recharge rates, and simulate the upwelling of deep saline groundwater and seawater intrusion. The model indicates that most of the groundwater recharge occurs near the outlet of the main channel. Average annual recharge to delta alluvial aquifers for 1982 to 2009 is estimated to be 2.16 × 10⁶ m³/yr. The main factors that control groundwater salinity are overpumping and recharge availability.     

新疆喀什三角洲地下水流系统的水化学和同位素标记

新疆喀什三角洲地下水“水质型”缺水问题较为突出，开展地下水流系统研究具有实际意义.采用水化学和环境同位素年龄测试法，在对喀什三角洲地下水含水系统划分基础上，对地下水化学和循环更新特征进行了分析研究.结果表明:三角洲含水系统由山前倾斜冲洪积平原潜水、河流冲积平原潜水和河流冲积平原承压水构成.沿地下水流向，水化学类型演化为HCO₃·SO₄-Ca→SO₄-Ca→SO₄·Cl-Mg·Na→SO₄·Cl-Na，TDS增高，水质趋向盐化.山前倾斜冲洪积平原为溶滤-径流区，河流冲积平原为径流-累盐区.研究区地下水更新速率为0.03%~16.35%·a-1，具有山前倾斜冲洪积平原潜水>河流冲积平原潜水>河流冲积平原承压水的特征.利用3H估算得出，山前倾斜冲洪积平原潜水年龄为8~49 a，平均值为29 a；河流冲积平原潜水年龄为14~>50 a，其中上部潜水平均年龄为24 a，下部潜水平均年龄大于50 a.利用14C估算得出，河流冲积平原潜水为476~33 623 a，平均值为8 106 a；河流冲积平原承压水为5 186~34 578 a，平均值为30 043 a，与潜水比为“更古老”的水.综合以上特征得出，喀什三角洲地下水含水系统可以划分为2个更新速率较快的局部水流系统（Ⅰ₁和Ⅰ₂）和一个循环滞缓的区域水流系统（Ⅱ）.      

Indication of hydrogen and oxygen stable isotopes on the characteristics and circulation patterns of medium-low temperature geothermal resources in the Guanzhong Basin,China

Guanzhong Basin is a typical medium-low temperature geothermal field mainly controlled by geo-pressure in the west of China.The characteristics of hydrogen and oxygen isotopes were used to analyze the flow and storage modes of geothermal resources in the basin.In this paper,the basin was divided into six geotectonic units,where a total of 121 samples were collected from geothermal wells and surface water bodies for the analysis of hydrogen-oxygen isotopes.Analytical results show that the isotopic signatures of hydrogen and oxygen throughout Guanzhong Basin reveal a trend of gradual increase from the basin edge areas to the basin center.In terms of recharge systems,the area in the south edge belongs to the geothermal system of Qinling Mountain piedmont,while to the north of Weihe fault is the geothermal system of North mountain piedmont,where the atmospheric temperature is about 0.2℃-1.8℃in the recharge areas.The main factors that affect the geothermal waterδ18O drifting include the depth of geothermal reservoir and temperature of geothermal reservoir,lithological characteristics,water-rock interaction,geothermal reservoir environment and residence time.Theδ18O-δD relation shows that the main source is the meteoric water,together with some sedimentary water,but there are no deep magmatic water and mantle water which recharge the geothermal water in the basin.Through examining the distribution pattern of hydrogen-oxygen isotopic signatures,the groundwater circulation model of this basin can be divided into open circulation type,semi-open type,closed type and sedimentary type.This provides some important information for rational exploitation of the geothermal resources.     

新疆天山北麓中段孔隙水水化学特征及苏打水的成因

天山北麓中段受构造控制,水文地质条件较为复杂.研究孔隙水水化学特征及苏打水（NaHCO₃型）形成机制对了解天山北麓中段地下水水文地球化学过程与地质条件之间的联系具有重要意义.基于新疆天山北麓中段平原区209组地下水水样,结合地质条件,采用半变异函数模型、绝对主成分得分多元线性回归模型（PCA/APCS-MLR）剖析了潜水和承压水中水化学类型空间分布特征、地下水化学组分源贡献率、苏打水形成的地质条件控制因素以及水文地球化学作用.结果表明:山前倾斜平原潜水、冲积平原潜水和承压水分别以Na₂SO₄、NaHCO₃和Na₂SO₄型水为主,其中苏打水分别占总水样的7.18%、14.83%、6.22%.承压水中Na+、HCO₃-、TDS空间自相关性较强,潜水中Na+、HCO₃-、TDS空间自相关性较弱,当水中TDS < 1 000 mg/L时更有利于NaHCO₃型水的形成.溶滤-富集因子（F1）、外界输入因子（F2）、原生地质因子（F3）和地质环境因子（F4）对地下水中水化学指标的平均贡献率分别为29.44%、15.99%、7.70%和6.71%.苏打水形成过程不仅受控于矿物溶滤、阳离子交换、混合作用和脱硫酸作用等多种水文地球化学作用,还受到地质环境、地质构造及水文地质条件的影响.