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1.
废弃矿山虽已不再开采,但废弃矿坑、旧冶炼场地、埋填的尾矿坝受雨水淋滤仍可通过地表径流对下游地区造成污染。研究废弃矿山水系沉积物及悬浮物中重金属的沿河道分布及相互关系具有重要的现实意义。本文以贵州万山汞矿区下溪河小流域系统作为研究区域,对沉积物及悬浮物中重金属元素进行初步调查,为监测和污染耕地进行修复提供基础资料。通过湿法消解的前处理方法,利用电感耦合等离子体质谱和原子荧光光谱法测定了沉积物及悬浮物样品中Cr、Ni、Cu、Cd、Pb、As、Hg、Zn、Co含量,查明污染现状及空间分布特征,以获取矿区污染物向下游迁移、扩散的信息。结果表明:沉积物中Hg含量范围为0.10~16.0μg/g(干重),平均值为5.79μg/g,是《国家土壤环境质量标准》二级土壤Hg限值的几十倍;Cd在部分站点超标;Ni、Cu、Co含量平均值均不超标;Hg和Cd的变异系数较大,显示空间分布不均的特征。沉积物中Hg为高潜在生态风险级别。研究区沉积物及悬浮物中的Hg浓度与河段的水动力条件有关,最大值出现在河道宽阔、水流平缓的站点。由于万山汞矿早已停止开采和冶炼,本研究提出,自然条件下废弃矿区的风化淋滤引起颗粒物输送是造成河流下游Hg和Cd污染的原因。  相似文献   
2.
张萍  冯婧  李哲  郭劲松  肖艳  刘静 《湖泊科学》2015,27(4):629-636
三峡水库汛末蓄水后易出现支流回水区磷累积现象,并在冬季末期常出现硅藻水华现象.为研究汛末蓄水的磷积累与冬季末期硅藻水华的相互关系,分析2013年1 3月三峡澎溪河高阳平湖库湾水体中碱性磷酸酶活性、磷形态的转化和藻类生长的协同过程.结果表明,总碱性磷酸酶活性(TAPA)及其最大反应速率(Vmax)、特异性碱性磷酸酶活性(PAPA/Chl.a)及PAPA与TAPA的比值(PAPA/TAPA)随着时间推移总体呈先增加后减小而后再增加减小的双峰趋势,分别在2月中旬和3月中旬达到峰值.根据冬季末期水华暴发程的特点将其分为Ⅰ、Ⅱ、Ⅲ、Ⅳ4个阶段.Ⅰ阶段为诱导期,水体活性磷主要来自藻类碱性磷酸酶分解的有机磷,藻类对磷过度摄取.Ⅱ阶段为过渡期,温度低,水体碱性磷酸酶活性相对较低.Ⅲ阶段为水华时期,水中碱性磷酸酶主要来源于细菌,叶绿素a浓度达到最大,溶解态反应性磷浓度达到最低;Ⅳ阶段为水华末期,水体叶绿素a浓度逐渐下降,溶解态反应性磷浓度回升,水中碱性磷酸酶主要来源于细菌.  相似文献   
3.
Jiongxin Xu 《水文科学杂志》2013,58(10):1926-1940
ABSTRACT

The tributary–trunk stream relationship is investigated with respect to hyperconcentrated flows and coupled wind–water processes in the Yellow River, China. Ten small tributaries that drain only 3% of the total drainage area of the trunk stream transport large amounts of relatively coarse sediment from the desert to the trunk stream during hyperconcentrated floods. The resultant strong sedimentation often jams the trunk stream, leading to serious disasters. This study reveals the cause of this interesting phenomenon and proposes countermeasures for disaster reduction. A typical sediment-jamming event (SJE) in July 1989 was thoroughly analysed based on the observational data, including the beginning, development and final stages of the event. An index of the geomorphologic effectiveness of the tributary on the trunk stream and a number of indices describing SJEs and the influencing factors are adopted, based on which a discrimination relationship for the occurrence of SJEs is established and some statistical relationships are also established. The SJE’s hydrological and geomorphologic impacts are discussed at short timescales (from several days to one month) and at long time scales (up to 46 years). The results may help to gain a new insight into the study of the tributary–trunk stream relationship, and provide useful information for sediment management and disaster-reduction planning in the drainage basin. Countermeasures are suggested to reduce the channel sedimentation and the risk of sediment-jamming disaters.
Editor M.C. Acreman Associate editor Q. Zhang  相似文献   
4.
刘松 《海洋与湖沼》1996,27(4):451-454
根据1990-1994年博斯腾湖小湖区出入湖水质矿化度监测和开都河西支入湖水量和出湖水量观测资料,采用水量平衡和盐量平衡关系推导出博斯腾湖小湖区出湖水质矿化度模型。  相似文献   
5.
The geochemical, mineralogical and lithological composition of modern stream bed material is examined in order to characterize sources and evaluate downstream mixing of sediments in the upper Fraser River drainage basin, British Columbia. The <63 µm fraction is emphasized for its relative mobility and ease of analysis using instrumental neutron activation. Overall, the composition of the stream sediments closely re?ects bedrock distribution. Samples dominated by limestone and dolostone, calcite and dolomite, and related elements (Ca, Mg, Sr etc.) correspond to Lower and Middle Cambrian carbonate bedrock largely con?ned to the Moose River sub‐basin. Clastic and non‐quartzite metamorphic lithologies, primary and secondary aluminosilicate minerals and related elements (Al, Cs, Rb etc.) are largely derived from Miette Group bedrock and associated with the uppermost Fraser River sub‐basin. Except in the case of the Moose River/Fraser River junction, the determination of proportional tributary contributions is complicated by variable or delayed mixing, localized ?oodplain or valley side sources, and limited contrast between source areas. At present the Moose River sub‐basin contributes a greater proportion of the total and ?ne‐grained sediment loads of the combined Fraser River than would be expected from drainage basin area alone. The imbalance is related to greater relief, precipitation and runoff in the Moose River sub‐basin; however, the spatial association of carbonate‐rich stream sediments, ice cover and carbonate bedrock exposure indicates that glaciers play a particularly important roll in generating ?ne‐grained ?uvial sediment. Since differences in glacier cover and glacier potential in the two major sub‐basins are likely to be persistent, and since relative sediment yields from the sub‐basins can be determined from sediment composition, a potential indicator of glacier variation and climate change during the Holocene is therein available. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   
6.
Abstract

The annual water balance of Lake Kyoga is estimated by a comparison of upstream and downstream flows in the Nile channel during a period of reliable measurements (1940–1977), supported by rainfall records over the basin. The relative contributions of net lake rainfall and tributary inflows are estimated. Changes in annual rainfall and seasonal distribution are examined.

Editor Z.W. Kundzewicz

Citation Brown, E. and Sutcliffe, J.V., 2013. The water balance of Lake Kyoga, Uganda. Hydrological Sciences Journal, 58 (2), 342–353.  相似文献   
7.
对2005年8月11日贡嘎山东坡雅家埂河特大型泥石流运动过程进行了描述,并采用现场实地勘查等手段,定量计算泥石流流速和流量等动力学特征,还运用得到的流量反演泥石流运动过程,从而得到雅家埂河特大型泥石流的形成机理。结果表明:雅家埂河特大型泥石流的形成与降雨有直接关系;雅家埂河支沟泥石流的群发性造成主河泥石流规模巨大;经对雅家埂河流域泥石流形成、发生的历史分析,推断出该流域泥石流存在18~21年的暴发周期;雅家埂河松散物源充足,降雨与水源丰富,地形地貌陡峭,极易再次发生规模较大的泥石流。  相似文献   
8.
潮汐河口支流建闸闸下淤积研究   总被引:6,自引:0,他引:6  
潮汐河口建闸的关键问题是闸下淤积。在潮汐河口支流口门上建闸,其闸下淤积面貌主要取决于干流主槽的位置,这与在潮汐河口干流上建闸的闸下淤积问题有着本质上的差异。以钱塘江河口支流曹娥江口门建闸为例,应用河床演变分析、动床实体模型和现场冲淤试验预测了曹娥江大闸闸下淤积面貌和淤积速率,为曹娥江大闸的建设提供了科学依据。  相似文献   
9.
Many upland river catchments in the UK have been historically mined for metals such as lead (Pb) and zinc (Zn), and as part of the mining process large quantities of metal contaminated sediment were released into the river system. The levels of sediment associated heavy metal contamination in river systems are largely controlled by the volumes of contaminated sediment released into the river and fluvial processes (e.g. erosion and deposition). As a consequence, the contamination patterns are often highly variable, which can make it difficult to create accurate assessments of the volumes of contaminated sediment remaining within the system. This paper uses a combination of techniques to establish the volumes of metal contaminated sediment remaining within the River Swale, UK. Firstly, using detailed field sampling and a geographical information system (GIS), it estimates the volumes of sediment remaining within one formerly mined tributary (Gunnerside Beck) which is then extrapolated to represent the contaminant volumes on other tributaries of the River Swale. Secondly, combining fresh field data with a range of existing data, volumes of contaminated sediment on the main stream of the River Swale are established. This two tier approach shows that significant volumes of contaminated sediment remain within the River Swale, with over 32 000 tonnes of Pb within the mined tributaries and 123 000 tonnes within the main channel belt of the River Swale itself. This represents approximately 28% of the Pb produced in the Swale catchment. Given these volumes and present day rates of removal, it may take over 5000 years for all of the metal rich sediment to be removed from the catchment. If the contaminated sediment is used as a tracer, present day rates of reworking of floodplain sediment can be calculated to be 0·02% per year. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
10.
In alluvial river systems, lateral inputs of water and/or sediment at junctions or undercut hillsides can disrupt what would otherwise be smooth downstream trends in mainstream bed elevation, channel gradient, and bed grain size. Generic styles of mainstream response to lateral inputs are investigated using a one‐dimensional sediment routing model with multiple grain size fractions. Numerical experiments isolate the effects of three para‐meters: ratio of tributary to mainstream water flux (QR), ratio of tributary to mainstream bedload flux (FR), and ratio of tributary to mainstream bedload diameter (DR). The findings are not unduly sensitive to the choice of initial conditions or to approximations made in the model. The primary distinction is between junctions that aggrade, causing local profile convexity with interrupted downstream fining, and junctions that degrade. The immediate effects of aggradation extend further upstream than downstream, whereas degradation is much more subdued and has no upstream impact. Aggradation is typical of coarse inputs (DR > 2), and degradation of fine inputs (DR < 1), but very high ratios of QR to FR also promote degradation. Both aggrading and degrading junctions can lead to a change in mainstream bed grain size well below the junction, with higher ratios of QR to FR producing a coarser distal bed. The effect of a tributary reflects the interplay between additional bed load and additional discharge to transport it. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
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