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1.
Characterization of stable isotope compositions (δ2H and δ18O) of surface water and groundwater in a catchment is critical for refining moisture sources and establishing modern isotope–elevation relationships for paleoelevation reconstructions. There is no consensus on the moisture sources of precipitation in the Yellow River source region during summer season. This study presents δ2H and δ18O data from 111 water samples collected from tributaries, mainstream, lakes, and groundwater across the Yellow River source region during summertime. Measured δ18O values of the tributaries range from ?13.5‰ to ?5.8‰ with an average of ?11.0‰. Measured δ18O values of the groundwater samples range from ?12.7‰ to ?10.5‰ with an average of ?11.9‰. The δ18O data of tributary waters display a northward increase of 1.66‰ per degree latitude. The δ18O data and d‐excess values imply that moisture sources of the Yellow River source region during summertime are mainly from the mixing of the Indian Summer Monsoon and the Westerlies, local water recycling, and subcloud evaporation. Analysis of tributary δ18O data from the Yellow River source region and streamwater and precipitation δ18O data from its surrounding areas leads to a best‐fit second‐order polynomial relationship between δ18O and elevation over a 4,600 m elevation range. A δ18O elevation gradient of ?1.6‰/km is also established using these data, and the gradient is in consistence with the δ18O elevation gradient of north and eastern plateau. Such relationships can be used for paleoelevation reconstructions in the Yellow River source region.  相似文献   

2.
Characteristics of annual runoff variation in major rivers of China   总被引：1，自引：0，他引：1  
The statistical properties of annual runoff in major rivers of China are studied based on the theory of stochastic process and technology of time series analysis. These properties include the characteristics of intra‐annual and inter‐annual variations of runoff, trends, abrupt changes and periodicities. The new findings from the intensive calculations and appropriate analysis of data in longer period are as follows: (i) compared with the nonuniformity of intra‐annual runoff before 1980, the nonuniformity of intra‐annual runoff in China generally decreased after 1980, except for Huaihe River and Songhua River; (ii) compared with the annual runoff before 1980, the annual runoff in China generally decreased after 1980 except for WangJiaba station in Huaihe River and Ha‐Erbin station in Songhua River; the frequency of continuous low flow and continuous high flow in Haihe River and the downstream of Yellow River is higher than those in other rivers in China; (iii) annual runoff shows a downward trend in major rivers of China especially in Haihe River, Liao River and the midstream and downstream of Yellow River; (iv) there exist certain abrupt changes of annual runoff in major rivers of China; the abrupt change‐points are different among different river basins; and (v) almost periodicities of annual runoff sequences in major rivers of China are generally 20 years below, that is, 3~7 and 12~20 years. The reasons for these changes are mainly caused by climate change and human activities. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

3.
Zhao L  Xiao H  Dong Z  Xiao S  Zhou M  Cheng G  Yin L  Yin Z 《Ground water》2012,50(5):715-725
There are many viewpoints about the sources of groundwater in the Badain Jaran Desert (BJD), such as precipitation and snowmelt from the Qilian Mountains (the upper reaches [UR] of the Heihe River Basin [HRB]) and precipitation from the BJD and the Yabulai Mountains. To understand the source of the groundwater of the BJD and their possible associations with nearby bodies of water, we analyzed variations of stable isotope ratios (δD and δ(18) O) and the deuterium excess (d-excess) of groundwater and precipitation in the BJD, of groundwater, precipitation, river and spring water in the UR, and of groundwater and river water in the middle and lower reaches (MR and LR) of the HRB. In addition, the climatic condition under which the groundwater was formed in the BJD was also discussed. We found obvious differences in δD, δ(18) O, and d-excess among groundwater in the BJD, nearby water bodies and the HRB. The groundwater δD-δ(18) O equation for the BJD was δD = 4.509δ(18) O-30.620, with a slope and intercept similar to that of nearby areas (4.856 and -29.574), indicating a strong evaporation effect in the BJD and its surrounding areas. The equation's slope of the BJD was significantly lower than those of HRB groundwater (6.634), HRB river water (6.202), precipitation in the BJD and Youqi (7.841), and the UR of the HRB (7.839). The d-excess (-17.5‰) of the BJD was significantly lower than those of nearby groundwater (-7.4‰), HRB groundwater (12.1‰), precipitation in the BJD (5.7‰) and in the UR of the HRB (15.2‰), and HRB river water (14.4‰). The spatial patterns of δ(18) O and d-excess values in the BJD suggest mixing and exchange of groundwater between the BJD and neighboring regions, but no hydraulic relationship between the BJD groundwater and water from more distant regions except Outer Mongolia, which is north of the BJD. Moreover, we conclude that there is little precipitation recharge to groundwater because of the obvious d-excess difference between groundwater and local precipitation, low precipitation, and high evaporation rates. The abnormally negative d-excess values in groundwater of the BJD indicate that this water was formed in the past under higher relative humidity and lower temperatures than modern values.  相似文献   

4.
The study of water vapour sources and water cycle patterns in the Yellow River source region is of great significance for ensuring water resource security in the arid and semi-arid regions of northern China. We established a precipitation stable isotope observation system in the Yellow River source region for three consecutive years (2020–2022), systematically analysed the spatial and temporal distribution characteristics of precipitation stable isotopes 2H and 18O in the Yellow River source region and their interrelationships with environmental factors and topography, and explored the regional water vapour transport pathways by using the HYSPLIT model and combining with the global reanalysis data. The results show that: (1) the δ18O and δ2H values of precipitation in the Yellow River source region follow the seasonal pattern, with the first half of the year being richer than the second half of the year; (2) the spatial variations of δ18O of precipitation in the Yellow River source region show a low in the southwest and a high in the northeast; (3) the water vapour source in the source area is basically stable, and the complex transport paths and the cross-effects of the local factors determine the stable isotope characteristics of the water, and the stable isotope characteristics of the water are determined by the cross-effects of the local factors, because the source of the water vapour and the local factors such as the height will not change significantly in the short term. Since the source of water vapour and local elevation factors will not change significantly in the short term, the precipitation pattern in the source area of the Yellow River can be considered to be basically stable.  相似文献   

5.
This paper presents the use of stable isotopes of water for hydrological characterization and flow component partitioning in the Red River Delta (RRD), the downstream section of the Red River. Water samples were collected monthly during 2015 from the mainstream section of the river and its right bank tributaries flowing through the RRD. In general, δ18O and δ2H river signatures were depleted in summer–autumn (May–October) and elevated in winter–spring (November–April), displaying seasonal variation in response to regional monsoon air mass contest. The Pacific equatorial–maritime air mass dominates in summer and the northern Asia continental air mass controls in winter. Results show that water of the RRD tributaries stems solely from local sources and is completely separated from water arriving from upstream subbasins. This separation is due to the extensive management of the RRD (e.g., dykes and dams) for the purposes of irrigation and inundation prevention. Mainstream river section δ18O and δ2H compositions range from ?10.58 and ?73.74‰ to ?6.80 and ?43.40‰, respectively, and the corresponding ranges inside the RRD were from ?9.35 and ?64.27‰ to ?2.09 and ?15.80‰. A combination of data analysis and hydrological simulation confirms the role of upstream hydropower reservoirs in retaining and mixing upstream water. River water inside the RRD experienced strong evaporation characterized by depleted d‐excess values, becoming negative in summer. On the other hand, the main stream of the Red River has d‐excess values around 10‰, indicating moderate evaporation. Hydrograph separation shows that in upstream subbasins, the groundwater fraction dominates the river flow composition, especially during low flow regimes. Inside the RRD, the river receives groundwater during the dry season, whereas groundwater replenishment occurs in the rainy season. Annual evaporation obtained from this hydrograph separation computation was about 6.3% of catchment discharge, the same order as deduced from the difference between subbasin precipitation and discharge values. This study shows the necessity to re‐evaluate empirical approaches in large river hydrology assessment schemes, especially in the context of climate change.  相似文献   

6.
Yinchuan Basin, a semi‐arid area located in Northwest China, is currently subject to increasing pressure from the altered hydrology due to the anthropogenic activities as well as increasing water demands for regional development. Sustainable water management across the region must be underpinned by a clear understanding of the factors that constrain water supply in this area. We measured the stable isotope of oxygen and hydrogen to determine the likely processes that control the interrelations among precipitation, surface water (Yellow River), and groundwater. The hydrogen and oxygen values demonstrate that 2 primary hydrochemical processes, mixing and evaporation/condensation, occurred in the Basin. Recharge proportions of precipitation and Yellow River were quantitatively evaluated based on the isotope mass balance method. The proportions of the Yellow River and atmospheric precipitation recharge are 87.7% and 12.3%, respectively. The evaporation proportions calculated with 18O and D by Rayleigh fractional equation are close to each other, which demonstrate that evaporation intensity increases following the flow direction of the Yellow River. The findings obtained in this study are useful for recognizing the significance of Yellow River to Yinchuan Basin, and some optimal allocation schemes can be adopted for a prospective development of this reputed area in Northwest China.  相似文献   

7.
Results of studying the concentration of total, dissolved, and suspended organic matter in the water of the Amur and its main tributaries (the rivers of Bureya, Songhua, etc.) in 2005–2006 are presented. A high concentration of organic matter of anthropogenic origin was recorded in the water of the Songhua River, which has a significant effect on the Amur water quality. The export of organic matter with the Amur River water into the Amur Liman was accessed.  相似文献   

8.
China is experiencing rapid urbanization that has changed the water quality of rivers, especially nutrient loads. In this study, a typical urban river located in a karst area, Chengguan River, was chosen to explore the influence of urbanization on river ecosystems based on nutrient concentration and nitrate isotopes. The results show monthly variability of water chemistry and nutrient concentration. Nutrient concentration in two tributaries and the mainstem showed significant spatial variability, with heavy N and P pollution in one tributary near a suburban area,indicating a response to different levels of urbanization.Measurements of nitrate dual isotopes suggest thatvolatilization, assimilation, nitrification, and denitrification all occur in the polluted river. Water chemistry and nitrate isotopes show that major nitrogen sources included domestic waste and agricultural input, such as chemical fertilizer and manure. The results suggest that urbanization increases nutrient concentrations and accelerates the riverine nitrogen dynamic, and point to the need to manage point sources of sewage effluents to improve the water quality of urban rivers in southwestern China.  相似文献   

9.
Rivers on territory of the Republic of Serbia can be separated to three sea drainage basins: Black, Adriatic and Aegean. Majority of rivers belong to the Black Sea drainage basin. The Danube is the most important river in Serbia and one of the most important rivers of Europe. All rivers investigated in this paper represent direct or indirect tributaries of the Danube River and as that, they are belonging to the Black Sea drainage basin. In this study, the water quality status and the spatial and temporal trends of seven major rivers in Serbia were assessed through the application of ten parameters of Water Quality Index. Ten year (2004–2013) public database of environmental data was used. Into considerations were taken differences between every river individually and difference between sample positions on every single river. Based on the chemical parameters of water quality, it can be seen that the biggest rivers in Serbia show different values of WQ parameters. The highest WQ value is measured on the Drina River, while the lowest value is measured on the Ju?na Morava and the Tisza River. Analyses of parameters per period of year show that there is a statistically significant difference between values during warm and cold periods.  相似文献   

10.
Here, we studied the isotope characteristics and source contributions of soil water in the permafrost active layer by collecting soil samples in July 2018 in Yangtze River basin. Soil moisture and temperature showed decreasing trends from 0–80 cm, and an increasing trend from 80–100 cm. The value of δ18O and δD first increased and then decreased in the soil profile of 0–100 cm; however, d-excess increased from 0–100 cm. δ18O values became gradually positive from the southwest to northeast of the study area, while d-excess gradually increased from southeast to northwest. The evaporation water line (EL) was δD = 7.56 δ18O + 1.50 (R2 = 0.90, p < 0.01, n = 96). Due to intense solar radiation and evaporation on the Tibetan Plateau, the elevation did not impact the surface soil. The altitude effect of the soil depths of 0–20 cm was not obvious, but the other soil layers had a significant altitude effect. Soil moisture and temperature were closely related to the stable isotopic composition of soil water. The contribution of precipitation to soil water on the sunny slope was 86%, while the contribution of the shady slope was 84%. However, the contribution of ground ice to soil water on sunny slope was 14% and the shady slope was 16%. The contribution of ground ice to soil water increased with increasing altitude on the sunny slope, but the contribution of ground ice to soil water had no obvious trend on the shady slope.  相似文献   

11.
中国水旱灾害的有序网络结构特征及其预测研究   总被引：8，自引：1，他引：7       下载免费PDF全文
信息有序性和可公度性是自然界的一种秩序,具有广泛的普适意义.历史资料表明,中国水旱灾害具有显著的有序性. 基于翁文波的信息预测理论,本文详细分析讨论了中国天灾时间序列的可公度信息系的特性,同时相应构建了长江、黄河历史大洪水以及全国大旱灾信息有序网络结构,并据此进行预测研究.结果表明：（1）我国长江流域大洪灾其可公度信息系的网状结构由基本周期60a、22a、38a、53a、82a所组成, 其中干支60a周期最具重要意义,它是天灾时序的主链.太阳活动的22a、11a等周期,也对长江洪涝灾害的节律产生重要影响.略去太久远的预测,未来长江大洪灾可能发生在2007～2008、2013、2020-2021年前后.（2）黄河大洪水也具有显著的可公度性,50a、22a～23a为其主要周期.未来黄河大洪水可能发生在2004、2014、2021、2027年前后.（3）未来我国大旱年份可能发生在2010、2016和2021～2022年前后.（4）宇宙是统一的整体. 日、地、月运行与天灾活动相互联系,相互依存和影响. 天灾的发生可视为地球内部因素和外部天文因素非线性作用的结果.巨洪、大旱更是多因强化综合作用的结果. 重大天灾时间序列所呈现的网络结构特性可能是其形成的一种机制. 因此,把巨灾放在天地生大系统范围内开展多学科的综合研究,这无疑是一条必由之路.（5）利用天灾时序的网络结构进行分析和中长期预测,它避免了传统数学分析的繁琐和数量的不可识别性,为我国防灾减灾提供了一种直观、便捷而有效的新方法.  相似文献   

12.
Accurately quantifying the evaporation loss of surface water is essential for regional water resources management, especially in arid and semi-arid areas where water resources are already scarce. The long-term monitoring of stable isotopes (δ18O and δ2H) in water can provide a sensitive indicator of water loss by evaporation. In this study, we obtained surface water samples of Shiyang River Basin from April to October between 2017 and 2019. The spatial and temporal characteristics of stable isotopes in surface water show the trend of enrichment in summer, depletion in spring, enrichment in deserts and depletion in mountains. The Local Evaporation Line (LEL) obtained by the regression of δ2H and δ18O in surface water has been defined by the lines: δ2H = 7.61δ18O + 14.58 for mountainous area, δ2H = 4.19δ18O − 17.85 for oasis area, δ2H = 4.08δ18O − 18.92 for desert area. The slope of LEL shows a gradual decrease from mountain to desert, indicating that the evaporation of surface water is gradually increasing. The evaporation loss of stable isotopes in surface water is 24.82% for mountainous area, 32.19% for oasis area, and 70.98% for desert area, respectively. Temperature and air humidity are the main meteorological factors affecting the evaporation loss, and the construction of reservoirs and farmland irrigation are the main man-made factors affecting the evaporation loss.  相似文献   

13.
The Yinchuan Plain has more than 2000 years of history of irrigation by diverting water from the Yellow River. Currently, the amount of water diverted from the Yellow River is about 21.7 times the water formed on the plain as a result of precipitation and inflow of groundwater. Under the intensive influence of irrigation, the plain changed from a desert into a rich and populous area, earning its name as ‘South China Beyond the Great Wall’, with lakes scattered across the Yinchuan Plain just as stars in the sky. In this research, 17 representative lakes were sampled to analyze and study 2H and 18O content; the results showed that lakes on the plain have undergone obvious non‐equilibrium evaporation. Recharges of the lakes can be divided into three types: recharge from the Yellow River, from groundwater and from both of these. The Craig–Gordon non‐equilibrium evaporation model for isotope fractionation was used to estimate the evaporation proportion of each lake. The results showed that evaporation from lakes on Yinchuan Plain is generally extensive under the dry climatic conditions. Most lakes have an evaporation proportion of over 25%, with the largest originating from Shahu lake and Gaomiaohu lake in the northern part of the plain, at 42.5% and 42.8%, respectively. The evaporation proportions calculated on the basis of 18O and 2H are very close to each other. This shows that the method used in this paper is feasible for estimating the evaporation proportions of lakes in areas with a heavy anthropogenic influence. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

14.
Time series of hydrogen and oxygen stable isotope ratios (δ2H and δ18O) in rivers can be used to quantify groundwater contributions to streamflow, and timescales of catchment storage. However, these isotope hydrology techniques rely on distinct spatial or temporal patterns of δ2H and δ18O within the hydrologic cycle. In New Zealand, lack of understanding of spatial and temporal patterns of δ2H and δ18O of river water hinders development of regional and national-scale hydrological models. We measured δ2H and δ18O monthly, together with river flow rates at 58 locations across New Zealand over a two-year period. Results show: (a) general patterns of decreasing δ2H and δ18O with increasing latitude were altered by New Zealand's major mountain ranges; δ2H and δ18O were distinctly lower in rivers fed from higher elevation catchments, and in eastern rain-shadow areas of both islands; (b) river water δ2H and δ18O values were partly controlled by local catchment characteristics (catchment slope, PET, catchment elevation, and upstream lake area) that influence evaporation processes; (c) regional differences in evaporation caused the slope of the river water line (i.e., the relationship between δ2H and δ18O in river water) for the (warmer) North Island to be lower than that of the (cooler, mountain-dominated) South Island; (d) δ2H seasonal offsets (i.e., the difference between seasonal peak and mean values) for individual sites ranged from 0.50‰ to 5.07‰. Peak values of δ18O and δ2H were in late summer, but values peaked 1 month later at the South Island sites, likely due to greater snow-melt contributions to streamflow. Strong spatial differences in river water δ2H and δ18O caused by orographic rainfall effects and evaporation may inform studies of water mixing across landscapes. Generally distinct seasonal isotope cycles, despite the large catchment sizes of rivers studied, are encouraging for transit time analysis applications.  相似文献   

15.
Stable isotopes of water have been widely used in understanding the hydrological functions of alpine inland catchments. This study identifies dominant runoff generation mechanisms based on isotopic data (δ18O and δ2H) of 487 rainwater and river-water samples from three tributaries in the Tarim River Basin in China for the period May–September 2013. The isotope hydrograph separation results provide a comprehensive overview of the rainfall influence on hydrological processes. Stream water and groundwater have varied responses to different intensities of rainfall events. Only a small proportion of rainfall is directly transported to the stream during such events. An inconsistent temporal trend of event water contribution is observed in the three catchments. The average fractional contributions of rainfall for the Tizinafu, Kumalak and Huangshuigou rivers are 10.3% (±1.1%), 9.7% (±2.9%) and 8.7% (±2.4%), respectively.  相似文献   

16.
The results of studies of variations of δ18O values in river water in Crimea Peninsula in January–February 2015–2017 are given. The variation range of δ18О in river water over the three years of studies never exceeded 3‰. A tendency toward an increase in δ18О in the water of the Salgir, Kacha, Al’ma, Bel’bek, Biyuk-Karasu from their sources to mouths was identified and explained by a decrease in evaporation in the mouth areas of the rivers relative to their sources and upper reaches, and the inflow of isotopically light precipitation (rain and snow) into the rivers in their upper reaches. The values of δ18О in waters of the rivers with regulated stream were found to increase under the effect of the Simferopol Reservoir on the Salgir River and the Izobil’nenskoe Reservoir on the Ulu-Zen’ River. The values of δ18О in the upper reaches of the large rivers of Kacha and Bel’bek (the northwestern slope of the Crimean Mountains) vary from ?8.7 to ?9.7‰, except for the rivers of Al’ma (?7.7‰) and Kokozka (?10.2‰) because of the different shares of groundwater in the recharge of these rivers.  相似文献   

17.
Stable isotopic compositions (δ18O and d-excess) from 25 rivers in Thailand were analysed monthly during 2013–2015. Results indicated that monsoon precipitation fundamentally influences the river isotopes. The overland flow supplied from monsoon precipitation and human-altered flow regimes produces considerable isotopic variability. Spatial and temporal variations were observed among four principal geographical regions. The seasonality of monsoon precipitation in mountainous Thailand produced large variations in isotopic compositions because most rainfall occurred during the southwest monsoon, and dry conditions prevailed during the northeast monsoon. The northern and northeastern regions are mountainous, highland areas. Low δ18O values were found in these regions, likely because of altitude effects on precipitation. Conversely, monsoonal precipitation continually supplies rivers in southern Thailand all year round, producing higher and more consistent δ18O values than in the other regions. The Chao Phraya plain in the central region experienced enrichment of δ18O river runoff related to evaporation in irrigation systems. Larger catchment areas and longer residence times resulted in more pronounced evaporation effects, producing lower values of d-excess and local river water line slopes compared with precipitation. The isotopic differences between river waters and precipitation were utilized to determine river recharge elevations and water transit time. The methods presented here can be used to explore hydrological interactions in other tropical river basins.  相似文献   

18.
Characterization of spatial and temporal variability of stable isotopes (δ18O and δ2H) of surface waters is essential to interpret hydrological processes and establish modern isotope–elevation gradients across mountainous terrains. Here, we present stable isotope data for river waters across Kyrgyzstan. River water isotopes exhibit substantial spatial heterogeneity among different watersheds in Kyrgyzstan. Higher river water isotope values were found mainly in the Issyk‐Kul Lake watershed, whereas waters in the Son‐Kul Lake watershed display lower values. Results show a close δ18O–δ2H relation between river water and the local meteoric water line, implying that river water experiences little evaporative enrichment. River water from the high‐elevation regions (e.g., Naryn and Son‐Kul Lake watershed) had the most negative isotope values, implying that river water is dominated by snowmelt. Higher deuterium excess (average d = 13.9‰) in river water probably represents the isotopic signature of combined contributions from direct precipitation and glacier melt in stream discharge across Kyrgyzstan. A significant relationship between river water δ18O and elevation was observed with a vertical lapse rate of 0.13‰/100 m. These findings provide crucial information about hydrological processes across Kyrgyzstan and contribute to a better understanding of the paleoclimate/elevation reconstruction of this region.  相似文献   

19.
《国际泥沙研究》2021,36(6):747-755
The magnitude and variation of the sediment loads transported by rivers have important implications for the functioning of river systems and changes in the sediment loads of rivers are driven by numerous factors. In this paper, the key drivers of changes in the sediment loads of the major rivers of China are identified by reviewing recent studies of changes in their sediment loads. Except for the Songhua River, which presents no clear tendency of change in runoff or sediment load, nearly all the major rivers of China are characterized by an apparent decline in annual sediment load. The total annual sediment load of major Chinese rivers transported to the coast decreased from 2.03 billion t/yr during the period 1955–1968 to 0.50 billion t/yr during the period 1997–2010. The primary drivers of changes in the sediment loads of the rivers are dam construction, implementation of soil and water conservation measures, catchment disturbance, agricultural practices, sand mining and climate change. Examples drawn from Chinese rivers are used to demonstrate the importance of these drivers. Construction of a large number of reservoirs in the Yangtze River basin represents the primary driver for the reduced sediment load of the Yangtze River. The implementation of soil and water conservation programmes is one of the key drivers for the sharp decline in the sediment load of the Yellow River. Catchment disturbance explains why the reduction of the sediment load of the Lancang-Mekong River at the Chiang Saen gauging station was much less than that at the Gajiu gauging station upstream. A reduction in sediment load resulting from the expansion of agricultural production may be the main driver for the reduced sediment load of the Huaihe River. The decrease in the sediment load of the Pearl River has been influenced by sand mining activities. Climate change is one of the key drivers responsible for the greatly reduced sediment load of the rivers in the Haihe River Basin.  相似文献   

20.
The suspended particulate and fine-grained floodplain sediments were collected from the main stream and tributaries of the Changjiang River for Sr-Nd isotopic measurements. The εNd(0) values gradually decrease downstream from -10.8 on average in the upper reaches to -12.3 in the lower reaches, whereas the 87Sr/86Sr ratios increase correspondingly, averaging 0.721899 and 0.725826 respectively in the upper and middle-lower reaches. The compositional variations primarily reflect the complex con- trols of provenance rocks, chemical weathering, and sediment characters between different catchments, among which the abnormal Sr-Nd isotopic compositions of the Yalong, Fujiang, Tuojiang and Yuanjiang rivers indicate the sediment provenance contributions from the Emeishan Basalt in the upper reaches and the old metamorphic and siliceous rocks in the middle-lower reaches. The Sr-Nd isotopic ratios of the Changjiang sediments can better reflect the average composition of weathered continental crust compared to other major rivers in the world because of the unique source rock types in the Changjiang drainage basin. The recognition of the Sr-Nd isotopic systematics of the Changjiang sediments will contribute to our understanding of the Changjiang evolution history and continental weathering processes during the Cenozoic, and also to reconstructing the paleoenvironmental changes in East China and the marginal seas.  相似文献   

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