Water geochemistry and boron isotope in the Xijiang River, SW China     

《中国地球化学学报》2006,25(B08):271-271

  相似文献   

Strontium isotope composition of the Arno River Valley waters （Tuscany, Italy） as a natural tracer of water-rock interaction and mixing processes     

Barbara Nisi Orlando Vaselli Antonella Buccianti Giulia Perini Angelo Minissale Giordano Montegrossi Franco Tassi 《中国地球化学学报》2006,25(B08):273-273

Sr isotope studies of surficial waters have highlighted that differences in the ^87Sr/^86Sr ratio and Sr concentration are primarily caused by mixing of waters of various origins with specific isotopic and chemical characteristics, resulting from water-rock interaction processes. In this paper we reported the first Sr isotopic ratios, coupled with water chemistry, the measurement was carried out on samples related to （1） the Amo River （Tuscany, central-northern Italy）, between the source and the mouth, （2） the most important tributaries and to （3） the thermal water discharges seeping out in the southern part of the basin. The main goals are： a） to use the ^87Sr/^86Sr ratio as a discriminative parameter of source areas, b） to define its variation along both the main course and principal tributaries, and c） to estimate the effects of the mixing process of the different end-embers. The outcropping rocks in the Amo River Basin are predominantly sedimentary, mainly made up of Mesozoic limestones, Oligocene sandstones and Plio-Pleistocene marine-lacustrine formations. Triassic and Mesosinian evaporites crop out in the Elsa and Era reaches, whereas Paleozoic quartzitic formations occur in the Mrs. Pisani area. Strontium isotopic composition is generally controlled by lithology and does not seem to be affected by anthropic input and flow rate. The ^87Sr/^86Sr ratios in the Arno Basin vary between 0.707963 and 0.712743, the highest ratios being related to waters circulating in the Palezoic rocks and Oligocene sandstone formations. Less radiogenic values pertain to the Elsa and Era tributaries where contributions related to the dissolution of evaporitic sequences, and mixing processes with the thermal discharges have been distinguished. The tributaries show that water samples in the pristine area have higher ^87Sr/^86Sr ratios than the respective tributaries from which water samples were collected near the confluence. Eventually, water samples collected along the Arno River, close to the mouth, tend to have Sr isotopic ratios similar to those of the present seawater.  相似文献   

Distribution of uranium and thorium in Irtysh River and the upriver wastewater from a rare metal mine impact on it     

Shehong LI Baoshan ZHENG Jianming ZHU Xiaoying YU 《中国地球化学学报》2006,25(B08):43-44

Uranium and Th are important radioactive elements. Most studies were focused on their environmental impact from uranium deposits and mining sites. But other sorts of mines such as rare metals mines are associated highly with uranium and thorium, too. In China, the Irtysh River is the only river that runs into the Arctic Ocean. The famous Koktokay rare metal pegmatite deposit is located in the headwater region of this river and has been exploited for several decades. The waste ore piled along the riverside as long as several kilometers. The wastewater flom the concentrating plant is discharged into the river directly. In addition, uranium and thorium can be leached from the waste ore into the river in the weathering process. So it is necessary to study the uranium and thorium distribution in the branch and trunk streams of the Irtysh River and the wastewater from the mining site impact on it. In this study, the contents of uranium and thorium in water samples from the Irtysh River and rare metal mine wastewater have been detected directly with ICP-MS. Uranium and thorium distribution and geochemical behaviors in the Irtysh River basin have been studied. The environmental uranium and thorium pollution status in the Irtysh River and wastewater from a rare metal mine impact on it have also been evaluated. The study shows that uranium and thorium contents in wastewater from a rare metal mine are as high as 78.311 μg/L and 0.627 μg/L, respectively, so we should also pay attention to the radioactive pollution from the rare metal mine. The average contents of U and Th in the branch streams of the Irtysh River are 0.572 μg/L and 0.015 μg/L, respectively. At the mean time, in the trunk of the Irtysh River, average thorium content is 0.019 μg/L while U is up to 2.234 μg/L, much higher than the average content （0.0309 μg/L） of the world rivers. From upstream to downstream in the trunk of the Irtysh River, thorium content declines gradually due to dilution by other branches and deposition itself.  相似文献   

Characteristics of trace elements in contaminated rivers and their environmental significance     

Xuyin YUAN Zhiyong SHEN Xu DENG Yun GAO 《中国地球化学学报》2006,25(B08):140-141

Several rivers researched around Taihu Lake in Chinese eastern plain are distributed to the west of the lake. Pollutants of different types from tributaries and inlets flow directly into the main rivers and finally into the lake. They change trace elements of rivers fi＇om which we can analyze. Researches about trace elements are helpful for understanding the pollutant characteristics, industrial structure and agricultural cultivation in the area of network rivers in the plain of China. Samples of water column, suspended matter and sediment were collected fi＇om the west rivers of Taihu Lake, which represent three typical rivers. Observation in the field and the primary composition analysis showed the Caoqiao River was mainly contaminated by industrial wastewater, the Liangxi River was discharged by domestic sewage and the Dapu River was principally input by farmland runoff. REE concentrations and their normalized curves showed obvious characters for rivers discharged by different sewages. The contents of total REE in water column followed the order of the Caoqiao River, the Dapu River and the Liangxi River fi＇om high to low. TREEs in suspended matter and sediments follow the order of the Dapu River 〉 the Caoqiao River 〉 the Liangxi River. REE normalized curves （for Australia shale） suggested that significant diversities were presented in water column, suspended matter and sediments, i.e., heavy REE enrichment in water, middle REE enrichment in suspended matter, and smooth curves for sediments. But the heavy pollution resulted in several anomalous curves in the same rivers. Some element ratios were selected as indices for polluted rivers based on their geochemical properties and diversities between rivers. The results displayed the discriminative indices for water column, suspended matter and sediment. The effective indices were Pb/Fe, Cr/Fe, Ni/Fe, Pb/Ni, Zn/Ni for water column, Cu/Al, Cu/Fe, Zn/Fe, K/Ca, K/Na, Pb/Co, Zn/Co for suspend matter and Pb/Fe, K/Ca, Ca/Mg, Zn/Ni for sediment, respectively. In general, rivers mainly discharged by industrial sewage have high ratios of Pb/Ni, K/Ca, are enriched in the middle REE and have positive Gd anomaly. The domestic sewage flowing into rivers reveals high ratios of Zn/Ni, Pb/Fe, and is enriched in the heavy REE, and has the positive Eu anomaly. If runoff of farmland enters into the rivers, it will have high ratios of Ca/Mg, K/Na, high lanthanum, and show the smooth normalized curves of REE.  相似文献   

Structure of flow over alluvial bedforms: an experiment on linking field and laboratory methods     

Alexander N. Sukhodolov  Juan J. Fedele  Bruce L. Rhoads 《地球表面变化过程与地形》2006,31(10):1292-1310

This paper presents results of a field study designed to examine the structure of flow over mobile and fixed bedforms in a natural stream and to compare the results with findings of previous laboratory studies within the framework of double time–space averaging approach. Measurements of turbulence were obtained in a small river in Illinois, USA, over a fine spatial grid of sampling points above a mobile sandy bedform and its artificially moulded replica. Flow structure over the artificial bedform is similar to that observed in laboratory studies, but is markedly different from the flow structure over natural bedforms. These differences are most pronounced in the roughness sublayer, whereas flow in the logarithmic layer over natural and artificial sand waves is fairly similar and exhibits spatial uniformity. The double time–space averaged distributions of turbulence statistics conform to the multilayer model of flow structure over bedforms. Mean velocity distributions indicate neither classical flow recirculation nor substantial reduction of velocities in the lee of bedform crests. However, vertical patterns of turbulence statistics over depth suggest that stacked wakes similar to those observed in laboratory studies exist above the bedforms. Thus, despite the absence of flow separation, wake development seems to be induced by the systematic influence of upstream bedforms on the vertical structure of turbulence. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

黄河的输沙量：过去、现在和将来——距今15万年以来的黄河泥沙收支表   总被引：4，自引：0，他引：4  

任美锷 《地球科学进展》2006,21(6):551-563

黄河于150 ka BP切穿三门峡，东流入海。黄河泥沙90%来自黄土高原。黄土高原土地利用和植被的变化对黄河输沙有决定性的影响。15万年以来，黄河进入华北平原的泥沙约70 000×108 t，其中10 ka BP以前占80%。10 ka BP以后的输沙量中，最后1040年黄土高原滥垦时期占60%。黄河泥沙的归宿，建造华北大平原占73%，流入海洋占26%。现在，黄河每年流入北黄海的泥沙不足0.2×108  t，其输运主要受海洋环流系统的影响。现在黄海每年向东海输运悬浮沉积物0.2×108~0.3×108 t，主要为废黄河三角洲及水下三角洲受侵蚀再悬浮的黄河泥沙。1996—2000年黄河下游连年断流，利津站的年径流量和输沙量只有1950—1979年30年平均的19%左右。今后20~30年内，由于气候变暖、工业、城市等引黄水量增加，黄河的入海泥沙量仍将偏少。  相似文献   

青藏高原北部不同地区河流和湖岸阶地的演化特征   总被引：1，自引：0，他引：1  

赵振明  李荣社 《地质通报》2006,(Z1)

把青藏高原北部空白区已完成的1∶25万区调成果报告中有关河流和湖岸地貌的剖面、实测数据提炼出来,将其位置点绘于同一张水系分布图上,然后根据不同位置、不同的剖面、不同的测试数据进行区域性对比研究,结果表明:①青藏高原北部昆仑山中部和东部地区,河谷、湖岸地貌都具有100kaBP、10kaBP、5～6kaBP的阶地,这3个时期东西部河谷、湖岸地貌的形成具有同步性;②昆仑山中部地区具有70kaBP的阶地,昆仑山东部地区具有50kaBP的阶地,这2个时期昆仑山东西部河流、湖岸地貌的形成不具有同步性。对该地区河流、湖岸地貌成因分析后认为,除气候作用外,河流阶地、湖岸阶地对高原北部的隆升具有一定的指示作用,表现为从西向东抬升速率逐渐减小,总体上同一地方从老到新抬升速率逐渐增加。  相似文献   

SLM和LPM模型日径流模拟对比分析——以陕西黑河为例     

赵静  李贺丽  陶林威 《地下水》2006,28(5):25-27

本文以黑河流域为例,根据可能收集的资料,试用SLM和LPM模型对日径流量进行了模拟和模拟精度检验,并对各模型的模拟结果作了对比分析,结果表明:①LPM可用于参考性预报,而SLM不能用于参考性预报,只能作参考性估报;②由于LPM模型吸收了季节变化信息,其检验期和率定期的评定效率均较高.结论:较之SLM,LPM模型的有效性和可靠性都有很大的提高,而且在一定程度上消减了洪峰预报误差,考虑了洪峰非线性变化的影响.  相似文献   

黄河河道整治工程险情分析   总被引：8，自引：1，他引：7  

张宝森  郭全明 《地质灾害与环境保护》2002,13(3):1-5

分析了黄河河道工程险情发生的原因,重点论述了丁坝附近的水流结构 特征及丁坝主要险情的机理,依据历年来工程出险资料统计分析了现状河道工程险情的特点,即现状河道条件下,河道工程重大险情基本上集中在控导工程一类,从险情的时间分布上、有涨峰阶段,洪峰阶段和落峰阶段,更为严重的是黄河河道工程险情不仅易在大水时期发生、小水时,非讯期也可能发生;在1000－2000m^3/s流量下出险的频率最高,可达到33.7%。  相似文献   

安徽境内长江岸带崩塌遥感调查   总被引：2，自引：0，他引：2  

杨则东  鹿献章 《国土资源遥感》1998,9(3):22-25

本文利用不同时相的航空航天遥感图像,调查了安徽省境内长江岸带类型,崩塌现状,并对江岸稳定性进行了分段描述与评价。  相似文献