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1.
Fei Zhang Zhangdong Jin Guang Hu Fuchun Li Yuewei Shi 《Environmental Earth Sciences》2009,59(2):297-313
The major cation and anion compositions of waters from the Lake Qinghai river system (LQRS) in the northeastern Tibetan Plateau
were measured. The waters were collected seasonally from five main rivers during pre-monsoon (late May), monsoon (late July),
and post-monsoon (middle October). The LQRS waters are all very alkaline and have high concentrations of TDS (total dissolved
solids) compared to rivers draining the Himalayas and the southeastern Tibetan Plateau. Seasonal variations in the water chemistry
show that, except the Daotang River, the TDS concentration is high in October and low in July in the LQRS waters. The forward
models were used to quantify the input of three main rivers (Buha River, Shaliu River, and Hargai River) from rain, halite,
carbonates, and silicates. The results suggest that (1) atmospheric input is the first important source for the waters of
the Buha River and the Shaliu River, contributing 36–57% of the total dissolved cations, (2) carbonate weathering input and
atmospheric input have equal contribution to the Hargai River water, (3) carbonate weathering has higher contribution to these
rivers than silicate weathering, and (4) halite is also important source for the Buha River. The Daotang River water is dominated
by halite input owing to its underlying old lacustrine sediments. The water compositions of the Heima River are controlled
by carbonate weathering and rainfall input in monsoon season, and groundwater input may be important in pre-monsoon and post-monsoon
seasons. After being corrected the atmospheric input, average CO2 drawdown via silicate weathering in the LQRS is 35 × 103 mol/km2 per year, with highest in monsoon season, lower than Himalayas and periphery of Tibetan Plateau rivers but higher than some
rivers draining shields. 相似文献
2.
3.
Chemical weathering is an integral part of the earth surface processes, whose spatial patterns and controlling factors on continental scale are still not fully understood. Highlands of the Asian continent have been shown having some of the highest observed rates of chemical weathering yet reported. However, the paucity of river gauge data in many of these terrains has limited determination of chemical weathering budget in a continental scale. A dataset of three large watersheds throughout northern Xinjiang in Central Asia is used to empirically identify chemical weathering regimes and interpret the underlying controlling factors. Detailed analysis of major ion ratios and a forward model of mass budget procedure are presented to distinguish the relative significances and contributions of silicate, carbonate weathering and evaporite dissolution. The analytical results show that carbonic acid is the most important weathering agent to the studied watersheds. Silicate weathering contributes, on average, ∼17.8% (molar basis) of total cations on a basin wide scale with an order of Zhungarer > Erlqis > Yili, indicating that silicate weathering, however, does not seem to be intense in the study basins. Evaporite dissolution, carbonate weathering and precipitation input contribute 43.6%, 29.7% and 8.9% of the total dissolved cations on average for the whole catchment, respectively. The three main morphological and hydrological units are reflected in water chemistry. Rivers from the montane areas (recharge area) of the three watersheds are very dilute, dominated by carbonate and silicate weathering, whereas the rivers of piedmont areas as well as the rivers of the sedimentary platform (runoff area) are dominated by carbonate weathering, and rivers of desert plain in the central Zhungarer basin (discharge area) are dominated by evaporite dissolution and are SO4 rich. This spatial pattern indicates that, beside lithology, runoff conditions have significant role on the regional chemical weathering regimes. Chemical weathering processes in the areas appear to be significantly climate controlled, displaying a tight correlation with runoff and aridity. Carbonate weathering are mostly influenced by runoff, which is higher in the mountainous part of the studied basins. The identification of chemical weathering regimes from our study confirmed the weathering potential and complexity of temperate watersheds in arid environment and that additional studies of these terrains are warranted. However, because the dominant weathering reactions in the sedimentary platform of northern Xinjiang are of carbonates and evaporites rather than silicate minerals, and the climatic factors have important role on the rock weathering regimes, we think that weathering at the arid temperate drainage system (Central Asia) is maybe not an important long-term sink for atmospheric CO2, if the future climate has no great change. 相似文献
4.
Chemical and Strontium Isotopic Compositions of the Hanjiang Basin Rivers in China: Anthropogenic Impacts and Chemical Weathering 总被引:1,自引:0,他引:1
The Hanjiang River, the largest tributaries of the Changjiang (Yangtze) River, is the water source area of the Middle Route
of China’s South-to-North Water Transfer Project. The chemical and strontium isotopic compositions of the river waters are
determined with the main purpose of understanding the contribution of chemical weathering processes and anthropogenic inputs
on river solutes, as well as the associated CO2 consumption in the carbonate-dominated basin. The major ion compositions of the Hanjiang River waters are characterized by
the dominance of Ca2+ and HCO3
−, followed by Mg2+ and SO4
2−. The increase in TDS and major anions (Cl−, NO3
−, and SO4
2−) concentrations from upstream to downstream is ascribed to both extensive influences from agriculture and domestic activities
over the Hanjiang basin. The chemical and Sr isotopic analyses indicate that three major weathering sources (dolomite, limestone,
and silicates) contribute to the total dissolved loads. The contributions of the different end-members to the dissolved load
are calculated with the mass balance approach. The calculated results show that the dissolved load is dominated by carbonates
weathering, the contribution of which accounts for about 79.4% for the Hanjiang River. The silicate weathering and anthropogenic
contributions are approximately 12.3 and 6.87%, respectively. The total TDS fluxes from chemical weathering calculated for
the water source area (the upper Hanjiang basin) and the whole Hanjiang basin are approximately 3.8 × 106 and 6.1 × 106 ton/year, respectively. The total chemical weathering (carbonate and silicate) rate for the Hanjiang basin is approximately
38.5 ton/km2/year or 18.6 mm/k year, which is higher than global mean values. The fluxes of CO2 consumption by carbonate and silicate weathering are estimated to be 56.4 × 109 and 12.9 × 109 mol/year, respectively. 相似文献
5.
Yosra Ayadi Naziha Mokadem Houda Besser Belgacem Redhaounia Faten Khelifi Samia Harabi Talel Nasri Younes Hamed 《Environmental Earth Sciences》2018,77(9):349
Teboursouk region, Northwestern Tunisia, is characterized by the diversity of its natural resources (petroleum, groundwater and minerals). It constitutes a particular site widely studied, especially from a tectonic stand point as it exhibits a complex architecture dominated by multi-scale synclinals and Triassic extrusions. It has typical karst landform that constitutes important water resources devoted for human consumption and agriculture activities, besides to the exploitation of the Mio-Plio-Quaternary aquifer (MPQ). Thus, hydrogeological investigations play a significant role in the assessment of groundwater mineralization and the evaluation of the used water quality for different purposes. Hence, the current study based on a combined geochemical–statistical investigation of 50 groundwater samples from the multilayered aquifer system in the study area give crucial information about the principal factors and processes influencing groundwater chemistry. The chemical analysis of the water samples showed that Teboursouk groundwater is dominantly of Ca–Mg–Cl–SO4 water type with little contribution of Ca–Mg–HCO3, Na–K–Cl–SO4 and Na–K–HCO3. The total dissolved solids (TDS) values range from 0.37 to 3.58 g/l. The highest values are located near the Triassic outcrops. Furthermore, the hydrogeochemistry of the studied system was linked with various processes such as carbonates weathering, evaporites dissolution of Triassic outcrops and anthropogenic activities (nitrate contamination). Additionally, the main processes controlling Teboursouk water system were examined by means of multivariate statistical analysis (PCA and HCA) applied in this study based on 10 physicochemical parameters (TDS, pH, SO4, HCO3, pCO2, Ca, Mg, Na, K, Cl and NO3). Two principal components were extracted from PCA accounting 61% of total variance and revealing that the chemical characteristics of groundwater in the region were acquired through carbonates and evaporite dissolution besides to nitrate contamination. Similarly, according to Cluster analysis using Ward’s method and squared Euclidean distance, groundwater from the studied basin belongs to five different groups suggesting that the geochemical evolution of Teboursouk groundwater is controlled by dissolution of carbonates minerals, chemical weathering of Triassic evaporite outcrops, cation exchange and anthropogenic activities (nitrate contamination). 相似文献
6.
Geochemistry of the dissolved load of the Changjiang Basin rivers: Anthropogenic impacts and chemical weathering 总被引:12,自引:0,他引:12
B. Chetelat C.-Q. Liu Z.Q. Zhao Q.L. Wang S.L. Li J. Li B.L. Wang 《Geochimica et cosmochimica acta》2008,72(17):4254-4277
This study focuses on the chemical and Sr isotopic compositions of the dissolved load of the rivers of the Changjiang Basin, one of the largest riverine systems in the world. Water samples were collected in August 2006 from the main tributaries and the main Changjiang channel. The chemical and isotopic analyses indicated that four major reservoirs (carbonates, silicates, evaporites and agriculture/urban effluents) contribute to the total dissolved solutes. The overall chemical weathering (carbonate and silicate) rate for the Changjiang is approximately 40 ton/km2/year or 19 mm/kyr, similar to that of the Ganges-Brahmaputra system, and the basin is characterized by carbonate and silicate weathering rates ranging from 17 to 56 ton/km2/year and from 0.7 to 7.1 ton/km2/year, respectively. In the lower reach of the Changjiang main channel, the weathering rates are estimated to be 36 and 2.2 ton/km2/year for carbonates and silicates, respectively. It appears that sulphuric acid may dominate chemical weathering reactions for some sub-basins. The budgets of CO2 consumption are estimated to be 646 × 109 and 191 × 109 mol/year by carbonate and silicate weathering, respectively. The contribution of the anthropogenic inputs to the cationic TDS of the Changjiang is estimated to be 15-20% for the most downstream stations. Our study suggested that the Changjiang is strongly impacted by human activities and is very sensitive to the change of land use. 相似文献
7.
Geochemical and isotopic characterization of groundwater and lake-water samples were combined with water and total dissolved solids balances to evaluate sources of groundwater quality deterioration in eastern Hetao Basin, Inner Mongolia, China. Groundwater quality is poor; 11 of 13 wells exceed drinking-water guidelines for at least one health-based parameter and all wells exceed aesthetic guidelines. The well water is largely derived from Yellow River irrigation water. Notably high uranium concentrations in the Yellow River, relative to world rivers, suggest groundwater uranium and other trace elements may originate in the river-derived irrigation water. Complex hydrostratigraphy and spatial variation in groundwater recharge result in spatially complex groundwater flow and geochemistry. Evapotranspiration of irrigation water causes chloride concentration increases of up to two orders of magnitude in the basin, notably in shallow groundwater around Wuliangsuhai Lake. In addition to evapotranspiration, groundwater quality is affected by mineral precipitation and dissolution, silicate weathering, and redox processes. The lake-water and TDS balances suggest that a small amount of discharge to groundwater (but associated with very high solute concentrations) contributes to groundwater salinization in this region. Increasing salinity in the groundwater and Wuliangsuhai Lake will continue to deteriorate water quality unless irrigation management practices improve. 相似文献
8.
Rahim Barzegar Asghar Asghari Moghaddam Evangelos Tziritis 《Environmental Earth Sciences》2016,75(23):1486
Aji-Chay River is one of the most important surface reservoirs of northwest of Iran, because it passes through Tabriz city and discharges to Urmia Lake, one of the largest permanent salty lakes in the world. The main objectives of the present study are to evaluate its overall water quality and to explore its hydrogeochemical characteristics, including the potential contamination from heavy metals and metalloids such as Co, Pb, Zn, Cd, Cu, Cr, Al and As. For this purpose, 12 water samples were collected from the main river body and its tributaries within Tabriz plain. The Piper diagram classified water samples mainly into Na–Cl and secondary into Ca–HCO3 and mixed Ca–Mg–Cl types, denoting a profound salinization effect. The cross-plots showed that natural geochemical processes including dissolution of minerals (e.g., carbonates, evaporites and silicates), as well as ion exchange, are the predominant factors that contribute to fluvial hydrogeochemistry, while anthropogenic activities (industrial and agricultural) impose supplementary effects. Cluster analysis classified samples into two distinct clusters; samples of cluster B appear to have elevated electrical conductivity (EC) values and trace metals concentrations such as Co, Pb and Cd, while SiO2 and Zn are low in comparison with the samples of the cluster A. The main processes controlling Aji-Chay River hydrogeochemistry and water quality were identified to be salinization and rock weathering. Both are related with geogenic sources which enrich river system with elevated values of Na+, Cl?, Ca2+, Mg2+, K+, SO4 2? and EC as a direct effect of evaporites leaching and elevated values of Pb and Cd as an impact from the weathering process of volcanic formations. According to the US salinity diagram, all of the water samples are unsuitable for irrigation as having moderate to bad quality. 相似文献
9.
利用Gibbs图、三角图、非参数检验、主成分分析等方法对比研究中国主要跨境河流(雅鲁藏布江、怒江、澜沧江、伊犁河、额尔齐斯河、黑龙江、红河和狮泉河)的水化学特征, 探讨不同气候、岩性等条件下跨境河流河水中溶解性物质的主控因素及来源。结果表明: 河流pH范围为7.60±0.93~8.29±0.14, 呈弱碱性; 总溶解性固体(TDS)范围为139.14±106.58~238.03±85.47mg/L, 均高于世界河流平均值(100mg/L), 为弱矿化度水; 河水水化学组成中阳离子以Ca2+为主, 阴离子以HCO3-为主, 水化学类型为HCO3--Ca2+型。主要离子在河流间存在显著性差异, 对河流水化学而言, 岩性为第一级影响因子; 河水离子主要受碳酸与硫酸参与的碳酸盐矿物化学风化作用控制, 总体上, 碳酸盐岩以方解石的风化作用为主; 雅鲁藏布江、澜沧江、伊犁河、黑龙江和狮泉河水化学还受到人为活动影响; 主要离子浓度未超过中国生活饮用水标准及世界卫生组织推荐标准。本研究为后续跨境流域岩石化学风化引起的大气CO2消耗这一地质碳汇提供依据。
相似文献10.
黄河水质地球化学 总被引:34,自引:0,他引:34
在对1958—2000年期间黄河水系100个站点水质监测资料进行统计分析的基础上,研究了黄河主要离子的地球化学。结果表明,黄河流域各区河水总溶解性固体(TDS)含量的差异达2~3个数量级,TDS的总平均值为452mg/L,是全球河流均值的4倍。Na+、K+、SO42-和Cl-的含量是世界河流均值的10~20倍。相比之下,河水TDS含量的季节差异却不大,远不及与此呈反比关系的流量的季节差异。黄河洪水期的水量通常是枯水期的4~5倍,但枯水期河水的TDS通常只是洪水期的2倍,完全不同于世界其他大河。黄河的离子化学主要受沉积岩(尤其是富含碳酸盐矿物的黄土)化学风化作用和在干旱气候影响下水中溶解盐的蒸发浓缩和结晶作用的控制。近半个世纪来黄河河道径流量有显著减少的趋势,这与新修建的众多水库的蓄水有关,与此相适应,近半个世纪来黄河水质表现出明显的盐渍化过程,这一过程主要由含盐量高的农田灌溉回水所引起。 相似文献
11.
Major ion chemistry,weathering processes and water quality assessment in upper catchment of Damodar River basin,India 总被引:5,自引:0,他引:5
Abhay Kumar Singh G. C. Mondal Suresh Kumar T. B. Singh B. K. Tewary A. Sinha 《Environmental Geology》2008,54(4):745-758
The chemical characteristics of surface, groundwater and mine water of the upper catchment of the Damodar River basin were
studied to evaluate the major ion chemistry, geochemical processes controlling water composition and suitability of water
for domestic, industrial and irrigation uses. Water samples from ponds, lakes, rivers, reservoirs and groundwater were collected
and analysed for pH, EC, TDS, F, Cl, HCO3, SO4, NO3, Ca, Mg, Na and K. In general, Ca, Na, Mg, HCO3 and Cl dominate, except in samples from mining areas which have higher concentration of SO4. Water chemistry of the area reflects continental weathering, aided by mining and other anthropogenic impacts. Limiting groundwater
use for domestic purposes are contents of TDS, F, Cl, SO4, NO3 and TH that exceed the desirable limits in water collected from mining and urban areas. The calculated values of SAR, RSC
and %Na indicate good to permissible use of water for irrigation. High salinity, %Na, Mg-hazard and RSC values at some sites
limit use for agricultural purposes. 相似文献
12.
13.
Northern latitude chemical weathering rates: clues from the Mackenzie River Basin, Canada 总被引:9,自引:0,他引:9
The main scope of this study is to investigate parameters controlling chemical weathering rates for a large river system submitted to subarctic climate. More than 110 river water samples from the Mackenzie River system (northern Canada) have been sampled and analyzed for major and trace elements and Sr isotopic ratios in the dissolved phase. The three main morphological units are reflected in water chemistry. Rivers from the Canadian Shield are very dilute, dominated by silicate weathering (Millot et al., 2002), whereas the rivers of the Rocky and Mackenzie Mountains as well as the rivers of the sedimentary Interior Platform are dominated by carbonate weathering and are SO4 rich. Compared to the rivers of the Mackenzie and Rocky Mountains, the rivers of the interior plains are organic, silica, and Na rich and constitute the dominant input term to the Mackenzie River mainstream. Rivers of the Canadian Shield area do not significantly contribute to the Mackenzie River system. Using elemental ratios and Sr isotopic ratios, a mathematical inversion procedure is presented that distinguishes between solutes derived from silicate weathering and solutes derived from carbonate weathering. Carbonate weathering rates are mostly controlled by runoff, which is higher in the mountainous part of the Mackenzie basin. These rates are comparable to the carbonate weathering rates of warmer areas of the world. It is possible that part of the carbonate weathering is controlled by sulfide oxidative weathering, but its extent remains difficult to assess. Conversely to what was stated by Edmond and Huh (1997), overall silicate weathering rates in the Mackenzie basin are low, ranging from 0.13 to 4.3 tons/km2/yr (Na + K + Ca + Mg), and confirm the negative action of temperature on silicate weathering rates for river basins in cold climates. In contrast to what has been observed in other large river systems such as the Amazon and Ganges Rivers, silicate weathering rates appear 3 to 4 times more elevated in the plains than in the mountainous headwaters. This contradicts the “Raymo hypothesis” (Raymo and Ruddiman, 1992). Isotopic characterization of suspended material clearly shows that the higher weathering rates reported for the plains are not due to the weathering of fine sediments produced in the mountains (e.g., by glaciers) and deposited in the plains. Rather, the relatively high chemical denudation rates in the plains are attributed to lithology (uncompacted shales), high mechanical denudation, and the abundance of soil organic matter derived from incomplete degradation and promoting crystal lattice degradation by element complexation. The three- to fourfold factor of chemical weathering enhancement between the plains and mountains is similar to the fourfold factor of enhancement found by Moulton et al. (2000) between unvegetated and vegetated watershed. This study confirms the negative action of temperature on silicate weathering for cold climate but shows that additional factors, such as organic matter, associated with northern watersheds are able to counteract the effect of temperature. This acceleration by a factor of 4 in the plains is equivalent to a 6°C increase in temperature. 相似文献
14.
River waters play a significant role in supplying naturally- and anthropogenically-derived materials to Lake Qinghai, northeastern Tibetan Plateau. To define the sources and controlling processes for river water chemistry within the Lake Qinghai catchment, high precision ICP-MS trace element concentrations were measured in water samples collected from the Buha River weekly in 2007, and from other major rivers in the post-monsoon (late October 2006) and monsoon (late July 2007) seasons. The distributions of trace elements vary in time and space with distinct seasonal patterns. The primary flux in the Buha River is higher TDS and dissolved Al, B, Cr, Li, Mo, Rb, Sr and U during springtime than those during other seasons and is attributed to the inputs derived from both rock weathering and atmospheric processes. Among these elements, the fluxes of dissolved Cr, B and Rb are strongly influenced by eolian dust input. The fluxes of dissolved Li, Mo, Sr and U are also influenced by weathering processes, reflecting the sensitivity of chemical weathering to monsoon conditions. The anthropogenic sources appear to be the dominant contribution to potentially harmful metals (Ni, Cu, Co, Zn and Pb), with high fluxes at onset of the main discharge pulses due, at least partially, to a runoff washout effect. For other major rivers, except for Ba, concentrations of trace elements are higher in the monsoon than in the post-monsoon season. A total of 38.5 ± 3.1 tons of potentially harmful elements are transported into the lake annually, despite human activities within the catchment being limited. Nearly all river water samples contain dissolved trace elements below the World Health Organization guidelines for drinking water, with the exception of As and B in the Daotang River water samples collected in late July probably mobilized from underlying lacustrine sediments. 相似文献
15.
A detailed investigation of the fluvial geochemistry of the Han River system allows to estimate the rates of chemical weathering and the consumption of CO2. The Han River drains approximately 26,000 km2 and is the largest river system in South Korea in terms of both water discharge and total river length. It consists of two major tributaries: the North Han River (NHR) and the South Han River (SHR). Distinct differences in basin lithology (silicate vs. carbonate) between the NHR and SHR provide a good natural laboratory in which to examine weathering processes and the influence of basin geology on water quality. The concentrations of major elements and the Sr isotopic compositions were obtained from 58 samples collected in both summer and winter along the Han River system in both 2000 and 2006. The concentrations of dissolved loads differed considerably between the NHR and SHR; compared with the SHR, the NHR had much lower total dissolved solids (TDS), Sr, and major ion concentrations but a higher Si concentration and 87Sr/86Sr ratio. A forward model showed that the dissolved loads in the NHR came primarily from silicate weathering (55 ± 11%), with a relatively small portion from carbonates (30 ± 14%), whereas the main contribution to the dissolved loads in the SHR was carbonate weathering (82 ± 3%), with only 11 ± 4% from silicates. These results are consistent with the different lithologies of the two drainage basins: silicate rocks in the NHR versus carbonate rocks in the SHR. Sulfuric acid derived from sulfide dissolution in coal-containing sedimentary strata has played an important role in carbonate weathering in the SHR basin, unlike in the NHR basin. The silicate weathering rate (SWR) was similar between the NHR and SHR basins, but the rate of CO2 consumption in the SHR basin was lower than in the NHR basin due to an important role of sulfuric acid derived from pyrite oxidation. 相似文献
16.
长江水系河水主要离子化学特征 总被引:12,自引:2,他引:12
2007年夏季采集了长江从上游沱沱河至入海口的干流原水样品36个,长江各主要支流水样品40个,分析了江水Ca2+、Mg2+、Na+、K+、HCO3-、SO42-、Cl-离子含量及溶解性SiO2等溶质成分。结果显示,长江流域水系离子化学组成主要受碳酸盐和蒸发岩风化控制,长江上游水离子化学呈现阳离子以K+和Na+为主,阴离子以Cl-和SO42-为主的蒸发岩类风化控制特征,但随着采样点位下移,离子含量逐渐呈现阳离子以Ca2+为主,阴离子以HCO3-为主的逐渐向碳酸盐风化过渡的特征;从时间变化上看,与20世纪50年代至1990年长江水离子化学数据相比,以Na+、K+、SO42-和Cl-为代表的所有阴阳离子均有明显增加;从通量上看,洞庭湖和鄱阳湖是长江离子两个最大的输入源,除洞庭湖和鄱阳湖外的其他长江各大支流中,岷江是长江Na+、K+、Ca2+、Mg2+、F-和HCO3-的最大输入源,嘉陵江是SO24-和溶解性SiO2的最大输入源;在几大世界河流中,长江是对海洋Mg2+、SO24-和Cl-的输入通量最大的河流,Ca2+和HCO3-通量仅次于亚马逊河。 相似文献
17.
巴丹湖区位于巴丹吉林沙漠的东南缘,发育很多被纵向沙垄一分为二、水体化学特征悬殊的双湖系统。前人对此类湖泊成因及风成地貌过程如何影响湖泊水文特征缺乏系统的研究。通过对沙漠东南缘局部风向和巴丹东、西湖湖盆形态的分析反演湖区的地貌演化,从而对湖泊水化学等特征的差异进行解释。水化学测试结果显示:巴丹东湖湖水的TDS为15 g/L左右,为微咸水;西湖的TDS是东湖的上百倍,为盐水。Google Earth遥感影像和DEM反映出巴丹吉林沙漠盛行NW风,东南缘风向及风力多变;巴丹东湖湖盆深于西湖湖盆。反演了巴丹湖地貌演化的3个阶段:(1)月牙湖形成阶段,即巴丹湖的形成阶段;(2)双湖系统形成阶段,气候干旱使湖泊水位降低、湖盆出露,在NW定向风作用下,新的新月形沙丘形成于湖盆上,将其分割从而导致巴丹东湖湖盆遭受风蚀;(3)纵向沙垄形成阶段,由于局部风向的改变,新月形沙丘在SW向风力作用下往NE向不断延伸,并转变成纵向沙垄。综合分析认为:气候变化是风成地貌演化的驱动力,多次风向的改变产生了湖盆地形西高东低的差异,导致东湖接受的浅层地下水补给大于西湖;当气候变得暖湿时,水位上升致两湖水体连通,由于东湖水位高于西湖,使东湖盐分释放、西湖盐分积累。因此,受地貌演化的影响,巴丹东、西湖形成了悬殊的盐度特征。 相似文献
18.
本次研究选择中国东部一个生态和环境空间分异极大的浅水湖泊(太湖)以及周围河流,分别于2003年7月和9月两次采集湖水和河水样品,分析其中的N2O浓度,并利用扩散模型公式估算水-气界面N2O交换通量。结果显示N2O饱和度的空间变化从70%不饱和到2708%过饱和变化范围很大。N2O饱和度的空间分布,N2O与CH4、无机氮、TDS(总溶解固体物质)之间的相关性都表明: 太湖重度富营养区N2O的产生极大地受到人为N输入的影响。然而,初步的通量分析显示湖泊N2O的释放因子不超过0.63%,小于河流中的默认值,N2O产率也略低于水环境中的平均值,太湖以面积为权重的释放通量平均值并不高,在7月和9月分别为14.0μmol/m2·d和9.7μmol/m2·d。这些结果表明流域人为N输入对整个湖泊N2O的促进作用是有限的,预计未来湖泊N2O释放不会因为人为活动增加而出现大幅度增加的状况。流域内各生态景观N2O释放量的比较,也表明富营养湖泊总体上仍然是一个十分有限的大气N2O释放源。相反,太湖周围河流存在较大的N2O释放速率,在7月和9月估算的N2O释放通量分别为142.1μmol/m2·d和28.8μmol/m2·d。将这一释放速率推广到整个流域后,预计河网的N2O释放量将占到耕作土壤的10%~50%,显示了河流对区域N2O质量平衡具有较重要的影响。 相似文献
19.
Water chemistry of Mansar Lake (India): an indication of source area weathering and seasonal variability 总被引:2,自引:0,他引:2
The chemistry of major elements (Ca, Mg, Na, K and Si) and anions (HCO 3, SO 4 and Cl) in the water of Mansar Lake was studied, based on seasonal data. The results show that total dissolved solid (TDS) concentration in a particular season is similar, but varies slightly in different seasons with a variation factor of less than 2. This is because the collections were made in the dry seasons and the Ca-precipitation is the cause for the seasonal variability. The major element chemistry of Mansar Lake is mainly controlled by rock weathering, with HCO 3 and Ca dominating the major ion composition because of the abundance of carbonate rocks in the basin. The results also indicate that the lake water is saturated with respect to calcite and/or dolomite during the spring season whereas it is undersaturated in the summer season. This contrast brings out seasonal variability. The lake shows disequilibrium with atmospheric CO 2 as a result of carbonate dissolution in the drainage basin. The study also shows that physical weathering/erosion is dominant and that chemical weathering is incipient. This is consistent with the Chemical Index of Alteration (CIA) data. 相似文献
20.
DING Tiping GAO Jianfei TIAN Shihong WANG Huaibai LI Ming WANG Chengyu LUO Xurong HANG Dan 《《地质学报》英文版》2016,90(1):285-351
The chemical and isotopic characteristics of the water and suspended particulate materials(SPM)in the Yellow River were investigated on the samples collected from 29 hydrological monitoring stations in the mainstem and several major tributaries during 2004 to 2007.TheδD andδ~(18)O values of the Yellow River water vary in large ranges from-32‰to-91‰and from-3.1‰to-12.5‰,respectively.The characters of H and O isotope variations indicate that the major sources of the Yellow River water are meteoric water and snow melting water,and water cycle in the Yellow River basin is affected strongly by evaporation process and human activity.The average SPM content(9.635g/L)of the Yellow River is the highest among the world large rivers.Compared with the Yangtze River,the Yellow River SPM has much lower clay content and significantly higher contents of clastic silicates and carbonates.In comparison to the upper crust rocks,the Yellow River SPM contains less SiO_2,CaO,K_2O and Na_2O,but more TFe_2O_3,Co,Ni,Cu,Zn,Pb and Cd.The abnormal high Cd contents found in some sample may be related to local industrial activity.The REE contents and distribution pattern of the Yellow River SPM are very close to the average value of the global shale.The averageδ~(30)Si_(SPM)in the Yellow River(-0.11‰)is slightly higher than the average value(-0.22‰)of the Yangtze River SPM.The major factors controlling theδ~(30)Si_(SPM)of the Yellow River are the soil supply,the isotopic composition of the soil and the climate conditions.The TDS in the Yellow River are the highest among those of world large rivers.Fair correlations are observed among Cl~-,Na~+,K~+,and Mg~(2+)contents of the Yellow River water,indicating the effect of evaporation.The Ca~(2+)and Sr~(2+)concentrations show good correlation to the SO_4~(2-)concentration rather than HCO_3~-concentration,reflecting its origin from evaporates.The NO_3~-contents are affected by farmland fertilization.The Cu,Zn and Cd contents in dissolved load of the Yellow River water are all higher than those of average world large rivers,reflecting the effect of human activity.The dissolved load in the Yellow River water generally shows a REE distribution pattern parallel to those for the Yangtze River and the Xijiang River.Theδ~(30)Si values of the dissolved silicon vary in a range from 0.4‰to 2.9‰,averaging1.34‰.The major processes controlling the D_(Si)andδ~(30)Si_(Diss)of the Yellow River water are the weathering process of silicate rocks,growth of phytolith in plants,evaporation,dissolution of phytolith in soil,growth of fresh water diatom,adsorption and desorption of aqueous monosilicic acid on iron oxide and human activities.The averageδ~(30)Si_(Diss)value of the Yellow River is significantly lower than that of the Nile River,Yangtze River and Siberia rivers,but higher than those of other rivers,reflecting their differences in chemical weathering and biological activity.Theδ~(34)S_(SO4)values of the Yellow River water range from-3.8‰to 14.1‰,averaging 7.97‰.There is some correlation between SO_4~(2-)content andδ~(34)S_(SO4).The factors controlling theδ~(34)S_(SO4)of the Yellow River water are the SO_4 in the meteoric water,the SO_4 from gypsum or anhydrite in evaporite rocks,oxidation and dissolution of sulfides in the mineral deposits,magmatic rocks and sedimentary rocks,the sulfate reduction and precipitation process and the sulfate from fertilizer.The~(87)Sr/~(86)Sr ratios of all samplesrange from 0.71041 to 0.71237,averaging 0.71128.The variations in the~(87)Sr/~(86)Sr ratio and Sr concentration of river water are primarily caused by mixing of waters of various origins with different~(87)Sr/~(86)Sr ratios and Sr contents resulting from water-rock interaction with different rock types. 相似文献