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1.
The Yangbajain geothermal field located in central Tibet is characterized by the highest measured reservoir temperature among all hydrothermal systems in China. The high-temperature geothermal fluid extracted from Yangbajain has been used for electricity generation for over 30 years. The geothermal wastewater generated by the Yangbajain power plants, with arsenic (As) concentrations up to 3.18 mg/L, drains directly into the Zangbo River, the major surface water at Yangbajain, which has elevated arsenic concentrations in the segments downstream of wastewater discharges. However, along the flow direction of the river, the arsenic concentration decreases sharply. Further inspection reveals that the concentrations of weakly bound arsenic, strongly adsorbed arsenic and total arsenic in riverbed sediment were affected by the drainage of geothermal wastewater, indicating that the sediment serves as a sink for geothermal arsenic. A logarithmic relationship between the integrated attenuation coefficients (IAC) for three river segments and the corresponding adsorption distribution coefficients of riverbed sediment samples also suggests that besides the dilution of geothermal arsenic in the Zangbo River, natural attenuation of arsenic may be caused by sorption to riverbed sediment, thereby reducing its health threat to local residents using the Zangbo River as a drinking water source.  相似文献   

2.
西藏羊八井地热电厂产生的高氟废水直接排入了流经羊八井热田的藏布曲（河）。利用离子色谱仪（IC）测定了藏布曲水样的氟浓度;通过浸提实验提取了藏布曲河床沉积物中的总氟和各种存在形态的氟,并确定了其含量。藏布曲河水的氟浓度明显受到地热废水排放的影响,河床沉积物中水溶态氟和可交换态氟的分布也与地热电厂排污口的位置有明显的对应关系。然而,河床沉积物中的铁锰结合态氟、有机束缚态氟、残余态氟和总氟的分布与地热废水排放无显著联系,表明地热废水来源氟在进入藏布曲后主要向河床沉积物中的水溶态氟和可交换态氟转化。藏布曲河床沉积物是地热废水来源氟的一个汇。  相似文献   

3.
Geothermal resources are very rich in Yunnan, China. However, source of dissolved solutes in geothermal water and chemical evolution processes remain unclear. Geochemical and isotopic studies on geothermal springs and river waters were conducted in different petrological-tectonic units of western Yunnan, China. Geothermal waters contain Ca–HCO3, Na–HCO3, and Na (Ca)–SO4 type, and demonstrate strong rock-related trace elemental distributions. Enhanced water–rock interaction increases the concentration of major and trace elements of geothermal waters. The chemical compositions of geothermal waters in the Rehai geothermal field are very complicated and different because of the magma chamber developed at the shallow depth in this area. In this geothermal field, neutral-alkaline geothermal waters with high Cl, B, Li, Rb Cs, As, Sb, and Tl contents and acid–sulfate waters with high Al, Mn, Fe, and Pb contents are both controlled by magma degassing and water–rock interaction. Geothermal waters from metamorphic, granite, and sedimentary regions (except in the Rehai area) exhibit varying B contents ranging from 3.31 mg/L to 4.49 mg/L, 0.23 mg/L to 1.24 mg/L, and <0.07 mg/L, respectively, and their corresponding δ11B values range from −4.95‰ to −9.45‰, −2.57‰ to −8.85‰, and −4.02‰ to +0.06‰. The B contents of these geothermal waters are mainly controlled by leaching host rocks in the reservoir, and their δ11B values usually decrease and achieve further equilibrium with its surrounding rocks, which can also be proven by the positive δ18O-shift. In addition to fluid–rock reactions, the geothermal waters from Rehai hot springs exhibit higher δ11B values (−3.43‰ to +1.54‰) than those yielded from other areas because mixing with the magmatic fluids from the shallow magma. The highest δ11B of steam–heated waters (pH 3.25) from the Zhenzhu spring in Rehai is caused by the fractionation induced by pH and the phase separation of coexisting steam and fluids. Given the strong water–rock interaction, some geothermal springs in western Yunnan show reservoir temperatures higher than 180 °C, which demonstrate potential for electricity generation and direct-use applications. The most potential geothermal field in western Yunnan is located in the Rehai area because of the heat transfer from the shallow magma chamber.  相似文献   

4.
The Tibetan plateau is characterized by intense hydrothermal activity and abnormal enrichment of trace elements in geothermal waters. Hydrochemistry and B isotope samples from geothermal waters in Tibet were systematically measured to describe the fractionation mechanisms and provide constraints on potential B reservoirs. B concentrations range from 0.35 to 171.90 mg/L, and isotopic values vary between −16.57 ‰ and +0.52 ‰. Geothermal fields along the Indus-Yarlung Zangbo suture zone and N–S rifts are observed with high B concentrations and temperatures. The similar hydrochemical compositions of high-B geothermal waters with magmatic fluid and consistent modeling of B isotopic compositions with present δ11B values imply that the B in high-B geothermal waters is mainly contributed by magmatic sources, probably through magma degassing. In contrast, geothermal fields in other regions of the Lhasa block have relatively low B concentrations and temperatures. After considering the small fractionation factor and representative indicators of Na/Ca, Cl/HCO3, Na + K and Si, the conformity between modeling results and the isotopic compositions of host rocks suggests that the B in low-temperature geothermal fields is mainly sourced from host rocks. According to simulated results, the B in some shallow geothermal waters not only originated from mixing of cold groundwater with deep thermal waters, but it was also contributed by equilibration with marine sedimentary rocks with an estimated proportion of 10%. It was anticipated that this study would provide useful insight into the sources and fractionation of B as well as further understanding of the relationships between B-rich salt lakes and geothermal activities in the Tibetan plateau.  相似文献   

5.
Arsenic mobility in fluvial environment of the Ganga Plain,northern India   总被引：1，自引：1，他引：0  
In the northern part of the Indian sub-continent, the Gomati River (a tributary of the Ganga River) was selected to study the dynamics of Arsenic (As) mobilization in fluvial environment of the Ganga Plain. It is a 900-km-long, groundwater-fed, low-gradient, alluvial river characterized by monsoon-controlled peaked discharge. Thirty-six water samples were collected from the river and its tributaries at low discharge during winter and summer seasons and were analysed by ICP-MS. Dissolved As and Fe concentrations were found in the range of 1.29–9.62 and 47.84–431.92 μg/L, respectively. Arsenic concentration in the Gomati River water has been detected higher than in its tributaries water and characteristically increases in downstream, attributed to the downstream increasing of Fe2O3 content, sedimentary organic carbon and silt-clay content in the river sediments. Significant correlation of determination (r 2 = 0.68) was also observed between As and Fe concentrations in the river water. Arsenic concentrations in the river water are likely to follow the seasonal temperature variation and reach the level of World Health Organization’s permissible limit (10 μg/L) for drinking water in summer season. The Gomati River longitudinally develops reducing conditions after the monsoon season that mobilize As into the river water. First, dissolved As enters into pore-water of the river bed sediments by the reductive dissolution of Fe-oxides/hydroxides due to microbial degradation of sedimentary organic matter. Thereafter, it moves upward as well as down slope into the river water column. Anthropogenically induced biogeochemical processes and tropical climatic condition have been considered the responsible factors that favour the release of As in the fluvial environment of the Ganga Plain. The present study can be considered as an environmental alarm for future as groundwater resources of the Ganga–Brahmaputra Delta are seriously affecting the human–environment relationship at present.  相似文献   

6.
The combined geothermal discharge from over 10,000 features in Yellowstone National Park (YNP) can be can be estimated from the Cl flux in the Madison, Yellowstone, Falls, and Snake Rivers. Over the last 30 years, the Cl flux in YNP Rivers has been calculated using discharge measurements and Cl concentrations determined in discrete water samples and it has been determined that approximately 12% of the Cl flux exiting YNP is from the Snake River. The relationship between electrical conductivity and concentrations of Cl and other geothermal solutes was quantified at a monitoring site located downstream from the thermal inputs in the Snake River. Beginning in 2012, continuous (15 min) electrical conductivity measurements have been made at the monitoring site. Combining continuous electrical conductivity and discharge data, the Cl and other geothermal solute fluxes were determined. The 2013–2015 Cl fluxes (5.3–5.8 kt/yr) determined using electrical conductivity are comparable to historical data. In addition, synoptic water samples and discharge data were obtained from sites along the Snake River under low-flow conditions of September 2014. The synoptic water study extended 17 km upstream from the monitoring site. Surface inflows were sampled to identify sources and to quantify solute loading. The Lewis River was the primary source of Cl, Na, K, Cl, SiO2, Rb, and As loads (50–80%) in the Snake River. The largest source of SO4 was from the upper Snake River (50%). Most of the Ca and Mg (50–55%) originate from the Snake Hot Springs. Chloride, Ca, Mg, Na, K, SiO2, F, HCO3, SO4, B, Li, Rb, and As behave conservatively in the Snake River, and therefore correlate well with conductivity (R2 ≥ 0.97).  相似文献   

7.
Large numbers of As-enriched geothermal springs are distributed at the southern Tibetan Plateau, and their influence on river water is still not clear. Lhasa River and its tributary, Duilong Qu located at downstream of the largest geothermal spring of the Tibetan Plateau, were selected for sampling during monsoon and non-monsoon seasons. Dissolved trace elements (B, Cr, Ni, Cu, Zn, As, Cs, Ba and U) were measured in river water samples by ICP-MS. The results show that due to contribution of geothermal spring, As levels of Duilong Qu (205.6 μg/L) and Lhasa River (12.7 μg/L) were higher during non-monsoon season than that of WHO guideline for drinking water (10 μg/L). Accordingly, As level of river water was lower during the monsoon season than that of the non-monsoon season due mainly to dilution process. Therefore, although Tibetan rivers are generally considered as free of contamination, geothermal springs cause As contamination of river water at some local regions and may harm the local residents. Further research is needed in other parts of the plateau to determine whether As level of groundwater of the related region is high.  相似文献   

8.
Chloride concentrations in waterways of northern USA are increasing at alarming rates and road salt is commonly assumed to be the cause. However, there are additional sources of Cl− in metropolitan areas, such as treated wastewater (TWW) and water conditioning salts, which may be contributing to Cl− loads entering surface waters. In this study, the potential sources of Cl− and Cl− loads in the Illinois River Basin from the Chicago area to the Illinois River’s confluence with the Mississippi River were investigated using halide data in stream samples and published Cl− and river discharge data. The investigation showed that road salt runoff and TWW from the Chicago region dominate Cl− loads in the Illinois Waterway, defined as the navigable sections of the Illinois River and two major tributaries in the Chicago region. Treated wastewater discharges at a relatively constant rate throughout the year and is the primary source of Cl− and other elements such as F− and B. Chloride loads are highest in the winter and early spring as a result of road salt runoff which can increase Cl− concentrations by up to several hundred mg/L. Chloride concentrations decrease downstream in the Illinois Waterway due to dilution, but are always elevated relative to tributaries downriver from Chicago. The TWW component is especially noticeable downstream under low discharge conditions during summer and early autumn when surface drainage is at a minimum and agricultural drain tiles are not flowing.  相似文献   

9.
Mineralogical and geochemical studies were undertaken in the volcanic area of Biancavilla (Catania, Italy) with the aim of explaining the nature of the high As and F contents of the area’s rocks. As and F contents in soils and groundwater were also investigated. The metasomatised benmoreite lavas show fluorine and arsenic concentrations up to about 3,000 and 1,000 mg/kg, respectively. Mineralogical analyses show that fluorine occurs mostly in fluoro-edenite and apatite-(CaF) crystals, both abundantly present in the altered rocks, while As is exclusively attributed to the apatite-(CaF) crystals. Specifically, arsenic was observed only at the borders of these apatite crystals. Leaching tests and sequential extraction procedures were carried out to evaluate the potential remobilisation of As and F by the mineral phases and the eventual risks induced by their spreading. The results of the leaching tests suggest that As is almost totally associated with the ‘easily reducible’ fraction and that it is released by the preferential dissolution of the arsenic enriched rims of apatite-(CaF) crystals. In soils, As concentration is relatively low (about 15 mg/kg, on average), while F ranges from 236 to 683 mg/kg. The underground waters supplying the town of Biancavilla show As and F contents lower than the allowed limits for drinking water, (As:10 μg/L, F:1–1.5 mg/L). The limited distribution of these rocks and the relatively limited mobilisation by the minerals both contribute to maintain low As and F values, in soils and groundwaters, despite the high values in metasomatised lava samples.  相似文献   

10.
伊通河水环境容量与污染防治对策的研究   总被引：4，自引：0，他引：4  
长春市唯一过境河流－伊通河是市区内工业废水和生活污水的主要受纳水体。依据各河段的区位、水力、污染、使用特征对伊通河环境进行功能区划分,然后按各功能区不同的控制标准计算了环境容量、污水允许排放量和污染物允许排放浓度,并与整体控制时的相应指标进行比较,最后提出分区控制的优越性和必要性及恢复伊通河水环境质量的减压增容措施,以确保地区的经济建设与环境保护协调发展。  相似文献   

11.
The important Iranian Karun River has never been investigated for the presence of potentially endocrine-disrupting chemicals, nonylphenol (NP). In this study, concentrations of NP were measured in water from Karun River and five wastewater discharge points into this river, collected during April to July 2010. The analytes were extracted by solid-phase extraction, and quantitative analyses were performed by HPLC–FLD. NP was detected in water and wastewater samples with 0.17–1.83 and 15.27–21.79 μg/L, respectively. The results showed that the NP content of aqueous phase of all wastewater samples higher than particulate phase, which were detected in the aqueous and particulate phases with mean concentrations of 12.8 ± 2.4 and 5.2 ± 1.2 μg/L, respectively. These data suggest that the NP levels in Karun river water are likely attributable to untreated municipal wastewaters discharged directly into the river. To our knowledge; this is the first study to evaluate NP concentrations in water and wastewater in Iran.  相似文献   

12.
西藏羊八井地热田热水的化学组成   总被引：12，自引：0，他引：12       下载免费PDF全文
赵平  多吉 《地质科学》1998,33(1):61-72
羊八井地热田深、浅层热水都是Cl-Na类型,具有相同的B/Cl比值,说明深层热水在上升通道中与冷水相混合形成了浅层热水。浅层流体自西北向东南流动,温度逐渐降低。浅层热储内普遍存在着水岩交换反应,对热水的化学组成有一定的影响。石英和玉髓地热温度计分别适用于计算深、浅层的热储温度。纳木错(湖)不是羊八井地热田的补给区。深层热水在井筒内绝热汽化时不会出现SiO2结垢,CaCO3是否会在井筒壁沉淀需要放喷较长时间来检验。文中还阐述了对热水的化学组分进行监测的必要性。  相似文献   

13.
The San Pedro River (SPR) is located in northern Sonora (Mexico) and southeastern Arizona (USA). SPR is a transboundary river that develops along the Sonora (Mexico) and Arizona (USA) border, and is considered the main source of water for a variety of users (human settlements, agriculture, livestock, and industry). The SPR originates in the historic Cananea mining area, which hosts some of the most important copper mineralizations in Mexico. Acid mine drainage derived from mine tailings is currently reaching a tributary of the SPR near Cananea City, resulting in the contamination of the SPR with heavy metals and sulfates in water and sediments. This study documents the accumulation and distribution of heavy metals in surface water along a segment of the SPR from 1993 to 2005. Total concentrations of Cd, Cu, Fe, Mn, Pb, and Zn in surface waters are above maximum permissible levels in sampling sites near mine tailing deposits. Nevertheless, a significant decrease in the Fe and SO4 2− in surface water (SO4 2−: 7,180–460.39 mg/L; Fe: 1,600–9.51 mg/L) as well as a gradual decrease in the heavy and transition metal content were observed during the period from 1994 to 2005. Approximately 2.3 km downstream of the mine tailings, the heavy metal content of the water drops quickly following an increase in pH values due to the discharging of wastewater into the river. The attenuation of the heavy metal content in surface waters is related to stream sediment precipitation (accompanied by metal coprecipitation and sorption) and water dilution. Determining the heavy metal concentration led to the conclusion that the Cananea mining area and the San Pedro River are ecosystems that are impacted by the mining industry and by untreated wastewater discharges arising from the city of Cananea (Sonora, Mexico).  相似文献   

14.
对云南热海和瑞滇地区地热流体的地球化学特征进行了分析和探讨,并据此评估了地热流体对环境的影响.结果显示,研究区的碱性热泉中K、Na、F、Cl、SiO_2的含量高,而只存在于热海地区的酸性热泉中SO_4~(2-)、Mn、Fe的含量高.热泉中As、Sb的含量范围分别在43.6～687μg/L和0.38～23.8 μg/L之间.热泉中以As(Ⅲ)为主,占了总砷的91%.地热流体中的As、Sb一部分被固定在泉华中,而另一部分则释放到了环境中,从而进入地下水和下游的田地中,对当地居民的健康造成威胁.  相似文献   

15.
为探究青藏高原搭格架地热区地热水、湖水、河水、冰雪融水等天然水体的水化学组成及物质来源控制因子,于2014年8月对该地区进行了考察和取样。利用紫外-可见光分光光度计和ICP-OES测定了水样中各阴、阳离子含量,利用Gas Bench连接同位素质谱仪测定了水样中溶解无机碳（DIC）同位素比值。结果表明,地热水中总溶解固体（TDS）含量为977.13~1 279.50 mg/L,阳离子以K+和Na+为主,阴离子以HCO3-和Cl-为主,湖水的TDS含量为77.81~810.94 mg/L,阳离子以Na+和Ca2+为主,阴离子以HCO3-(CO32-)和SO42-为主,地热水和湖水的水化学类型为HCO3-Na型;河水和冰雪融水的各离子含量较低,水化学类型为HCO3-Ca型;地热水的DIC浓度范围为9.2~15.4 mmol/L,δ13CDIC值为-9.09‰~-0.95‰;湖水的DIC浓度为1.1~9.7 mmol/L,δ13CDIC值为-8.84‰~-0.27‰。根据水化学Gibbs分布模式图判断出区域水化学特征主要受硅酸盐岩风化控制,以钠长石和钾长石风化为主,但是地热水的水化学组分受到硅酸盐岩和蒸发盐岩共同控制。通过碳同位素比值分析对区域主要风化过程中CO2的来源示踪表明,湖区周围的硅酸盐风化其碳源主要为土壤CO2,热泉区硅酸盐水解其碳源为地球深部CO2输入。   相似文献   

16.
Large variations are reported in the B concentrations and isotopic ratios of river and thermal spring waters in Guadeloupe, Lesser Antilles. Rivers have δ11B values around 40‰ and B concentrations lower than 30 μg/L, while thermal springs have δ11B of 8–15‰ and B concentrations of 250–1000 μg/L. River samples strongly impacted by hydrothermal inputs have intermediate δ11B and B contents. None of these surface water samples have δ11B comparable to the local unweathered volcanic rocks (around 0‰), implying that a huge isotopic fractionation of 40‰ takes place during rock weathering, which could be explained by preferential incorporation of 10B during secondary mineral formation and adsorption on clays, during rock weathering or in the soils. The soil-vegetation B cycle could also be a cause for such a fractionation. Atmospheric B with δ11B of 45‰ represents 25–95% of the river B content. The variety of the thermal spring chemical composition renders the understanding of B behavior in Guadeloupe hydrothermal system quite difficult. Complementary geochemical tracers would be helpful.  相似文献   

17.
The Diyadin Geothermal area, located in the eastern part of Anatolia (Turkey) where there has been recent volcanic activity, is favorable for the formation of geothermal systems. Indeed, the Diyadin geothermal system is located in an active geodynamic zone, where strike-slip faults and tensional cracks have developed due to N–S regional compression. The area is characterized by closely spaced thermal and mineralized springs, with temperatures in the range 30–64 °C, and flowrates 0.5–10 L/s. Thermal spring waters are mainly of Ca(Na)-HCO3 and Ca(Mg)-SO4 types, with high salinity, while cold groundwater is mostly of Ca(Na, Mg)-HCO3 type, with lower salinity. High contents of some minor elements in thermal waters, such as F, B, Li, Rb, Sr and Cs probably derive from enhanced water–rock interaction.Thermal water samples collected from Diyadin are far from chemical equilibrium as the waters flow upward from reservoirs towards spring vents and possibly mix with cooler waters. The temperatures of the deep geothermal reservoirs are estimated to be between 92 and 156 °C in Diyadin field, based on quartz geothermometry, while slightly lower estimates are obtained using chalcedony geothermometers. The isotopic composition of thermal water (δ18O, δ2H, δ3H) indicates their deep-circulating meteoric origin. The waters are likely to have originated from the percolation of rainwater along fractures and faults to the deep hot reservoir. Subsequent heating by conduction due to the presence of an intrusive cupola associated with the Tendurek volcano, is followed by the ascent of deep waters to the surface along faults and fractures that act as hydrothermal conduits.Modeling of the geothermal fluids indicates that the fluid is oversaturated with calcite, aragonite and dolomite, which matches travertine precipitation in the discharge area. Likewise, the fluid is oversaturated with respect to quartz, and chalcedony indicating the possibility of siliceous precipitation near the discharge areas. A conceptual hydro-geochemical model of the Diyadin thermal waters based on the isotope and chemical analytical results, has been constructed.  相似文献   

18.
The Yangbajing geothermal field with the highest reservoir temperature among Chinese hydrothermal systems is located about 90 km northwest to Lhasa City, capital of Tibet, where high temperature geothermal fluids occur in two reservoirs: a shallow one at a depth of 180–280 m and a deep one at 950–1,850 m. In this study, Oxygen-18 and deuterium isotope compositions as well as 87Sr/86Sr ratios of water samples collected from geothermal wells, cold springs and surface water bodies were characterized to understand the genesis of geothermal fluids at Yangbajing. The results show that the deep geothermal fluid is the mixing product of both magmatic and infiltrating snow-melt water, whereas the shallow geothermal fluid is formed by the mixing of deep geothermal fluid with cold groundwater. Using a binary mixing model with deep geothermal fluid and cold groundwater as two endmembers, the mixing ratios of the latter in most shallow geothermal water samples were calculated to be between 40 and 50%. The combined use of O, H, and Sr isotopes proves to be an effective approach to depict the major sources of geothermal fluids and the mixing processes occurring in two reservoirs at Yangbajing.  相似文献   

19.
Arsenic and fluoride in a loess aquifer in the central area of Argentina   总被引：3，自引：0，他引：3  
The objective of this study is to analyze the geochemical conditions associated with the presence of arsenic (As) and fluoride (F) in the phreatic aquifer of Coronel Moldes, in the central sector of the Argentine Chacopampean plain. The studied aquifer is composed of silty sand sediments of aeolian origin, typically loess-like sediments. The geochemical composition of water varies from sodium bicarbonate to sodium sulfate-chloride water. As contents range from low concentrations, below detection level, to 250 μg/l. High values of F (up to 12 mg/l) were recorded. A high As–F correlation was found (R 2 = 0.84). The pH varied from 7.31 to 8.85 and the nitrates reached concentrations up to 200 mg/l, indicating an oxidant environment. The highest values of As and F agreed with sodium bicarbonate waters as well as with the highest values of pH recorded. There was a high correlation between As and F− as well as between As and the Na/Ca ratio. The composition and texture of loess, low permeability and hydraulic gradients together with the geochemical features of sodium bicarbonate waters are proper conditions for the mobilization of As and F in groundwater in the central area of Argentina.  相似文献   

20.
The thermal waters of Kizildere and environs in the Buyuk Menderes rift zone are marked by boron concentrations of up to 32 mg/l, and flow rates of ～250 l/s into the Buyuk Menderes River, thus increasing boron contents of the river water up to 4.4 mg/1l (e.g., in 1992), for a river-water flow rate of 2 m3/s. These high boron concentrations poison plants, particularly citrus fruits, in irrigated agricultural areas of the rift zone. High boron contents in the thermal waters can be attributed to: (1) unstable boron-bearing mineral phases (e.g., feldspars, muscovites, tourmalines, hornblendes, and biotites) in the metamorphic rocks, proven by experimental leaching tests of various rocks; and (2) a magmatic input, corroborated by isotope analyses of δ11B, δ13C, and δ34S of the thermal waters. Additionally, Neogene boron deposits in northwestern Turkey have to be taken into consideration as possible sources of boron, which may contribute to these anomalous concentrations by leaching of boron-bearing minerals. Meteoric input of boron into the thermal water reservoir is ruled out because the boron contents of groundwater from the Buldan horst in the northern part of the study area is below detection limits (0.01 mg/l). There is no single reason for the high boron concentrations measured in the thermal waters of Kizildere and environs; rather, a concurrence of several natural factors is likely.  相似文献   

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