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1.
Soil properties relating to the sediment volume of Ando soils varied depending on their physical state. The water content is a useful index property for the sediment volume of field-moist soils. The sediment volume of air-dried soils increased with decreasing clay content and with increasing organic carbon content. The water retention at 52% relative humidity was related to the sediment volume of soils subjected to a sonic wave treatment. An explanation of this behaviour is given in terms of the tendency of Ando soils to form water-stable aggregates. 相似文献
2.
Gianni Andreottola Luca Bonomo Giorgia De Gioannis Elisa Ferrarese Aldo Muntoni Alessandra Polettini Raffaella Pomi Sabrina Saponaro 《Journal of Soils and Sediments》2010,10(1):142-150
Purpose
The fairly high amounts of sediments dredged in coastal or internal water bodies for navigational and/or environmental purposes claims for the identification of appropriate management strategies. Dredged sediments are frequently affected by organic and inorganic contamination, so that their reuse, as an alternative to final landfill disposal, could need remediation. In this framework, a two-year joint research project was carried out to assess the feasibility of different remediation technologies for the treatment of polluted sediments. 相似文献3.
《CATENA》2005,60(3):227-237
Measurements of suspended sediment concentration are of importance in soil erosion research and soil and water conservation practices and monitoring. A method of measuring sediment concentration with capacitance sensors was advanced in this study. The relationships between the sediment concentration in flowing water and the output of capacitance sensor, as affected by temperature, flow velocity, soil types and salt contents were experimentally investigated with two types of capacitance sensors. The temperature used in the experiments ranged from 0 to 40 degrees centigrade. Salt concentrations (NaCl) in the flowing water ranged from 0 to 5 g/L and the flow velocity varied between 0.5 to 2.0 m/s. Two types of soil (a loam and a sandy soil) with sediment concentration up to 70% were studied. The results showed that suspended sediment concentrations, over a wide range, were linearly correlated with the outputs of capacitance sensors. The outputs of the capacitance sensor increased with temperature, with little influence from flow velocity, soil types and salt concentration. The results suggest that capacitance sensors may be used for sediment concentration measurement of flowing water. 相似文献
4.
通过分析黄河流域水沙运动过程和水沙分布特点,给出了流域泥沙配置单元,指出流域泥沙配置单元的配置量随着流域治理工程实施、径流条件等不断变化;1950—1999年,流域水土保持滞沙、水库拦沙、河道滞沙、两岸引沙用沙、河口淤积与入海泥沙等配置单元年均配置沙量占流域产沙量(17.63亿t)的14.24%、14.05%、12.19%、10.56%和50.77%;阐述了水库拦沙多、河道淤积严重是黄河流域泥沙配置现状不合理的主要原因,指出流域水沙资源优化配置和泥沙资源化是维护黄河健康的重要途径;结合黄河下游长期泥沙处理与利用的经验和教训,总结了黄河下游泥沙资源化的主要途径,包括淤临淤背、河道治理与河槽维护、引洪淤灌与土壤改良、灌区堆沙高地农田化、建筑材料转化、河口泥沙造地和疏浚泥沙利用、湿地塑造等。 相似文献
5.
浅沟侵蚀是黄土高原重要的侵蚀类型,上方汇水对坡面浅沟侵蚀具有重要的影响。采用野外放水冲刷试验,定量分析26°坡耕地在上方来水量为5、10和15L/min时对坡下方浅沟侵蚀产沙及其水动力参数的影响。结果表明：上方来水的汇入使浅沟水流流速明显增大,雷诺数、弗劳德数、水流功率和剪切力分别增大33%～76%、21%～47%、29%～72%和18%～42%,阻力系数减少11%～13%,导致浅沟侵蚀产沙量明显增大;除流速和弗劳德数外,其余水动力参数随放水时间的延长呈递增趋势;上方来水使浅沟侵蚀产沙量相对增量与水流功率和剪切力相对增量均呈幂函数关系。 相似文献
6.
不同土壤管理措施下基于水蚀过程的含沙量变异及其驱动 总被引：2，自引：0，他引：2
In order to prevent soil erosion in southern China, a study was performed to determine the drivers of sediment concentration variation using simulated rainfall and four soil management systems under field condition. Four soil management systems, i. e., forest and grass coverage (FG), forest coverage with disturbed soil surface (FD), contour tillage (CT) and downslope tillage (DT), were exposed to two rainfall intensities (40 and 54 mm h-1) using a portable rainfall simulator. The drivers of sediment concentration variation were determined by the variations of runoff rate and sediment concentration as well as their relationships. The effects of the four soil management systems in preventing water and soil losses were compared using runoff rates and sediment concentrations at steady state. At runoff initial stage, sediment concentration variation was mainly driven by rainfall and management. The degree of sediment concentration variation driven by flow varied with different soil management systems. Three best relationships between runoff rate and sediment concentration were identified, i. e., reciprocal (CT), quadratic (FG and FD) and exponential (DT). At steady state, runoff rates of the four soil management systems varied slightly, whereas their sediment concentrations varied greatly. FG and CT were recommended as the best soil management systems for preventing water and soil losses. 相似文献
7.
The effect of five Russian and foreign hydrogels on the water retention curve (WRC) and the related physical parameters of soils and sediments differing in their genesis and degree of dispersion has been considered on the basis of a proprietary version of the equilibrium centrifugation method. The new version of the method with the use of a high-speed centrifuge has allowed obtaining WRC in a wide range of matric potentials from 0 to 3000 J/kg (pF = 4.5) with the experimental estimation of almost all the soil-hydrological constants. The first analysis of strongly swelling polymer hydrogels (SSPHs) on WRC and the structural curves of the pore size distribution in heavy-textured soils has been performed, and the possibility has been shown of increasing their water capacity at the swelling of SSPHs in the region near water saturation. The most efficient is the use of SSPHs in light soils, which allows their water retention to be brought to the level of native loamy sands and loams in the SSPH content range of 0.1–0.3% of the enclosing coarse material. The best characteristics were observed for the Russian hydrogel VUM developed by the Institute of Technical Chemistry of the Urals Branch of the Russian Academy of Sciences and produced by the Urals Plant for Chemical Reagents. 相似文献
8.
Transport of polychlorinated biphenyls (PCBs) in freshwater mesocosms from sediment to water and air
With sediment as a source the flux of PCBs to water and air was followed in mesocosms with and without fish for two vegetation seasons. The fish represented the largest lipid pool in the mesocosm, and their presence increased the flux of PCBs across the sediment/water interface. The flow of PCBs from sediment to water followed a seasonal pattern with higher rates during summer than in the winter. The rates were governed by the turbation activity of benthic invertebrates, the extent of gas production in the sediment, the amount and quality of the lipid pools in the water column, and the solubility of the PCBs. The greatest amount of PCBs among the lipid pools was found in the dissolved extractable lipids, which also showed the highest concentration of PCBs calculated on a lipid basis. After about 1.5 yr, >90% of the PCBs added was still in the sediment. The remainder was distributed within the mesocosms to various extents depending on the amount and quality of the lipid pools, or transferred into the air. Transfer into the air was governed by PCB concentrations in the water, and by water temperature. The flow was highest during summer, when the surface microlayer renewed its load of PCBs every 8th day. 相似文献
9.
This study reports on the short-term impact of constructing a rural cycle way on the suspended sediment load (SSL) of Golborne Brook, Cheshire, UK between August 2003 and February 2004. A float switch activated automatic water sampler retrieved 275 water samples during the 5 months following ground disturbance, which were analysed for their suspended sediment concentration (SSC). SSC vs. discharge (Q) rating curves established for three phases of the disturbance were combined with a 10-min Q record to estimate SSLs before, during and after the work. A three-fold increase in SSL was observed 5 m downstream of where drainage ditches created alongside the cycle way entered Golborne Brook. There is strong evidence that the SSLs decreased to near their pre-disturbance levels within 5 months. Re-growth of natural vegetation on the roadside drainage ditches cleared during the construction work along with the build up of natural deciduous organic debris dams (consisting mainly of leaves, twigs and small branches from hedgerows alongside the ditches) at the ends of the drainage ditches some 1–2 m before they discharged into Golborne Brook contributed to the reduced SSLs observed downstream. Further research into the precise role played by these deciduous organic debris dams in trapping sediment is needed. 相似文献
10.
Goal, Scope and Background
Distribution of hydrophobic organic contaminants in abiotic compartments is essential for describing their transfer and fate in aquatic ecosystems. Taihu Lake is the third largest freshwater lake in China. Water quality of Taihu Lake has deteriorated greatly during the last decades and has threatened the water supply. The aim of the present study was to investigate the partitioning of polycyclic aromatic hydrocarbons (PAHs) among overlying water, suspended particulate matter (SPM), sediments, and pore water in Meiliang Bay, Taihu Lake and to provide useful information for the ecological engineering in this area.Materials and Methods
Overlying water and surface sediment were sampled from six sites in Meiliang Bay, Taihu Lake, China. Within 72 h of sampling, sediments were centrifuged to obtain the pore water. Overlying water samples were filtered to separate dissolved and SPM samples. After extraction, samples were purified following a clean-up procedure. PAH fraction was obtained by elution with a mixture of hexane: DCM (7:3, V/V) and analyzed by GC/MS.Results
PAHs concentrations in overlying water varied from 37.5 ng/L to 183.5 ng/L. Concentrations of PAHs in pore water were higher than those in overlying water. The total concentrations of 16 priority PAHs in sediments ranged from 2091.8 ng/g-dw to 4094.4 ng/g-dw. PAHs concentrations on SPM were decreased with suspended solid concentrations (SSC). Total PAHs concentrations on SPM varied in the range of 3369.6 ng/g-dw to 7531.1 ng/g-dw. The partition coefficients between sediment and overlying water (log K oc) for PAHs with log K ow<5 were positively correlated with their octanol-water partition coefficients (log K ow) (n=39, r=0.79, p<0.0001). Partition coefficients between sediment and pore water (log K oc′) for all PAHs were also significantly correlated with their log K ow values (n=48, r=0.82, p<0.0001).Discussion
In general, PAHs derived from combustion sources tend to bind strongly to soot particles in natural sediment. Consequentially, K oc values observed in the natural environment could be orders of magnitude higher than those predicted by linear correlation relationships under laboratory conditions. In the present study, the ratio of log K oc values to log K ow values falls consistently above 1, indicating that the sediment soot carbon in the bay was more attractive for PAHs than n-octanol. The log K oc′ was also higher than that predicted under laboratory conditions, suggesting that the measured pore water PAH concentrations were lower than those predicted. That is to say, not all the sediment PAHs can be available to partition rapidly into sediment pore waters. A variation in soot content is a possible reason. Furthermore, concentrations of PAHs on SPM were higher than those in sediments. The compositions of PAHs on SPM and in sediments were similar, indicating the importance of re-suspension process of sediments in the partitioning process of the shallow lake.Conclusions
The results indicated the equilibrium partitioning model could be used to predict PAHs distribution in various phases of a shallow lake in the stagnation period, but re-suspension processes should be considered to modify the relationship between log K ocs and log K ows.Recommendations and Perspectives
Concentration, particle size and composition of resuspended particles could affect the relationship between log K ocs and log K ows. Further work should be done under field conditions, especially where a steady thermodynamic equilibrium state could be assumed.11.
Testing three Mediterranean shrub species in runoff reduction and sediment transport 总被引：1，自引：0，他引：1
Runoff yield and sediment delivery are compared in three shrub species (Medicago arborea, Atriplex nummularia, and Psoralea bituminosa) with natural (matorral) vegetation in an experimental plot set. The planted species are arranged in discontinuous rows perpendicular to the slope, acting as barriers to the direction of the surface water flow. The study was carried out from 1988 to 1995, in which 56 erosive rain events were monitored in runoff production and in soil losses, together with their intrinsic characteristics (duration, intensity and rainfall). Growth of the three shrub species (height, vegetation cover, and stem diameter) and the influence on soil properties during this period were recorded. Because of certain characteristics of the study area (shallow soils, high levels of carbonates, stoniness) and the climate (an especially intense period of drought since 1990), the growth of these plants was very irregular. M. arborea gave the best protection against water erosion reducing sediment production by more than 58% compared to the bare soil. However, the protection afforded by this species never reached that obtained with natural vegetation, which reduced sediment production by almost 75%. 相似文献
12.
Jiongxin Xu 《CATENA》2002,49(4)
According to the yearly maximum suspended sediment concentrations (SSC) in the Yellow River and its tributaries, the rivers are divided into three types of more than 300, 20–300, and less than 20 kg/m3. The middle Yellow River basin is located in the transitional zone from subhumid to semiarid climates, and covered by a thick loess mantle. Neighboring on the desert areas to the northwest, the surface material of the Loess Plateau exhibits some marked areal differentiation in grain size and forms three zones covered by sandy loess, (typical) loess and clayey loess from northwest to southeast. Controlled by these physico-geographical conditions, the grain size of river-transported sediment shows some particular characteristics; at small water discharge or SSC, the grain size of suspended sediment abruptly decreases to a minimum with increasing water discharge or SSC. At water discharge of more than ca. 40 m3/s or at SSC of more than ca. 40 kg/m3, the grain size increases with water discharge or SSC.During the low-stage season, the relatively clear baseflow may scour the coarse bed materials, so the suspended sediment is relatively coarse. In the rainy season, rainstorm runoff washes out fine loess materials to the river, making suspended sediment fine. During relatively strong rainstorms, there often occur hyperconcentrated flows at SSC of more than 300 kg/m3. The relatively coarse grains could then remain suspended in the mixture of water and fine suspended sediment. 相似文献
13.
Mathapelo P. Seopela Robert I. McCrindle Sandra Combrinck Thierry J-C. Regnier 《Journal of Soils and Sediments》2016,16(12):2740-2752
Purpose
Rivers feeding into the Loskop Dam, South Africa, pass through coal mining and heavily industrialised areas. Previous studies investigating mass mortalities of crocodile and fish in the river system, revealed the presence of organic compounds, including polycyclic aromatic hydrocarbons (PAHs), in their tissues.Materials and methods
Samples were collected from nine sites within the dam in winter and summer. Liquid-liquid and microwave-assisted extraction was used for preconcentrating PAHs from water and sediment samples, respectively. Extracts were analysed by gas chromatography-mass spectrometry in the selected ion monitoring mode to determine the presence and levels of the 16 United States Environmental Protection Agency (US EPA)-priority PAHs.Results and discussion
Significant levels of PAHs were found in both water and sediment samples. Concentrations were higher in sediments than in water, as well as in samples collected in winter. Levels of PAHs in sediments were generally higher than those reported by many researchers for other water bodies in industrialised areas. Zebrafish embryos were used to assess potential risks associated with the water and sediment, and to determine the effects of PAHs on aquatic life. Embryos, exposed to intact water and sediment samples, as well as to diluted sediment extracts, were monitored for 120 h post fertilisation. Sediment proved more toxic to zebrafish embryos than water, causing delayed embryo development and malformations.Conclusions
These findings are alarming as they indicate that this water system is under stress. These findings can be typical of any water system situated in a coal mining and industrial region.14.
The characteristics of sediment discharge in the Yukon River, Alaska were investigated by monitoring water discharge, water turbidity and water temperature. The river-transported sediment, 90 wt.% or more, consists of silt and clay (grain size62.5 μm), which probably originated in the glacier-covered mountains mostly in the Alaska Range. For early June to late August 1999, we continuously measured water turbidity and temperature near the estuary and in the middle of Yukon River by using self-recording turbidimeters and temperature data loggers. The water turbidity (ppm) was converted to suspended sediment concentration (SSC; mg/l) of river water, using a relation between simultaneous turbidity and SSC at each of the two sites, and then, the suspended sediment discharge, approximately equal to water discharge times SSC, was numerically obtained every 1 or 2 h. It should be noted that the sediment discharge in the Yukon River is controlled by SSC rather than water discharge. As a result, a peak sediment discharge occurred in mid or late August by local sediment runoffs due to glacier-melt (or glacier-melt plus rainfall), while a peak water discharge was produced by snowmelt in late June or early July. Application of the “extended Shields diagram” indicates that almost all the river-transported sediments are under complete suspension. 相似文献
15.
Philipp Egeler Kevin S. Henry Caroline Riedhammer 《Journal of Soils and Sediments》2010,10(3):377-388
Purpose
Standardized sediment toxicity assays often employ periodic additions of uncontaminated food to sustain energy and growth requirements of the test organisms. Consequently, selective feeding on this uncontaminated food may reduce exposure to sediment particles containing the test substance. To address this issue, some standard guidelines propose to add food to the sediment before spiking with the test substance to account for multiple exposure routes, including ingestion of contaminated food. The present study focused on the influence of different feeding regimens and compositions of the aqueous medium on water quality (ammonia concentrations) and test organism development. 相似文献16.
Kuang-Chung Yu Shien-Tsong Ho Jiunn-Kae Chang Sheue-Duanlai Lai 《Water, air, and soil pollution》1995,84(1-2):31-49
The distribution and correlation of benthic bio-community, water and sediment pollutants were evaluated with multivariate analysis from data collected over six samplings at 12 sites in the Ell-Ren river system, Taiwan. A total of 41 benthic algae species, 8 aquatic insect species and 2 annelid species were collected. On the basis of both principal component and correlation matrix analyses, we defined six water and sediment pollutant components to reveal common behaviour. Metrioenemus sp., Tubifex sp., Bacillariophyceae and Cyanophyceae could tolerate the environment at highly polluted sites. Caenis sp., Rhithrogena sp. and Baetis sp. preferred sites that were aerobic, and their populations were negatively correlated (52–56%) with detrital heavy metals in sediment. The population of benthic algae was positively variated with lead of the “bound to organic matters and sulphides” fraction, but negatively with copper in the detrital pattern. Results suggested that benthic bio-community demonstrated measurable relationships with water and sediment pollutants in Ell-Ren river system, and could be used as indicators to assess the water quality of river over a longer period. 相似文献
17.
基于流量对泥沙沉积敏感度的滴灌灌水器水力性能动态评价 总被引：1，自引：1，他引：0
提出了基于流道泥沙沉积过程的滴灌灌水器水力性能动态评价方法,以反映灌水器浑水流量对其进口压力变化和泥沙沉积过程的敏感程度。以3种双向流道灌水器和1种迷宫式流道灌水器为研究对象,在3种进口压力下,分别进行清水和浑水试验。结果表明,迷宫式流道灌水器流态指数浑水条件下相比清水增大74.85%,1#,2#和3#双向流道灌水器分别增大38.47%,41.26%,46.25%,流道中泥沙的沉积使其水力性能变差;双向流道灌水器浑水流态指数均小于迷宫式流道灌水器;随着浑水试验次数的增加,4种灌水器浑水流态指数总体趋势是逐渐增大,成因是流道中泥沙沉积的累积效应,反映了浑水条件下水力性能的动态变化过程;相同压力变化,浑水条件下迷宫式流道灌水器流量变化率比清水时增大40.43%,1#,2#和3#双向流道灌水器分别增大17.23%,19.43%,22.33%,迷宫式流道灌水器增大程度大于双向流道灌水器,导致其水力性能相对双向流道灌水器下降较大;4种灌水器水力性能与抗堵性能差异均显著,且双向流道灌水器的水力性能与抗堵性能均优于迷宫式流道灌水器,说明灌水器流道结构形式及结构参数是影响灌水器整体性能的重要因素。 相似文献
18.
针对陡坡工程堆积体水土流失严重的问题,通过野外模拟降雨试验开展植被不同近地表特征对堆积体产流产沙和蓄水减沙效益特征影响的定量研究。选择土石混合堆积体（10%砾石质量分数,坡度30°）作为工程侵蚀下垫面的典型代表,并以裸坡（bare slope, BS）为对照,定量分析了植被在3种近地表特征条件下（完整植株（intact grass,IG）,不含叶（not leaf,NL）,只含根系（only root,OR））对堆积体产流产沙特征和蓄水减沙效益影响。结果表明：1）植被在IG条件下延缓坡面径流发生使其较BS滞后,效益达50.74%～188.98%,但不完整植被（NL、OR）会加速径流发生使其较BS提前2.19%～70.12%;2）植被在NL和OR下的瞬时径流率比IG增大0.20%～185.58%,在降雨强度1.8 mm/min的瞬时径流率甚至比BS高1.20%～169.10%;植被在IG和NL条件下瞬时侵蚀速率比BS减少0.91%～98.71%,但在降雨强度达到1.8 mm/min时OR条件下甚至增大侵蚀使其比BS高6.76%～75.63%;3）随降雨强度增大,植被在NL和OR条件下的减沙效益由95.18%和68.31%分别递减至46.58%和-68.13%,但对IG下的减沙效益影响小（效益差异＜2%）,平均蓄水效益随降雨强度增大而减小。不同堆积体水沙呈显著线性相关（R2在0.40～0.88）,且径流率达到4 L/min会显著改变植被对堆积体坡面防护效益。提出开展堆积体生态修复时选择冠层丰富的植被,同时要避免外部因素对植被造成损害。研究结果对于揭示植被防护扰动边坡侵蚀机制具有重要意义,可为堆积体植被修复提供实践指导。 相似文献
19.
《CATENA》2005,64(1):61-80
Accelerated soil erosion is a worldwide problem because of its economic and environmental impacts. To effectively estimate soil erosion and to establish soil erosion management plans, many computer models have been developed and used. The Revised Universal Soil Loss Equation (RUSLE) has been used in many countries, and input parameter data for RUSLE have been well established over the years. However, RUSLE cannot be used to estimate the sediment yield for a watershed. Thus, the GIS-based Sediment Assessment Tool for Effective Erosion Control (SATEEC) was developed to estimate soil loss and sediment yield for any location within a watershed using RUSLE and a spatially distributed sediment delivery ratio. SATEEC was enhanced in this study by developing new modules to: 1) simulate the effects of sediment retention basins on the receiving water bodies, 2) estimate the sediment yield from a single storm event, and 3) prepare input parameters for the Web-based sediment decision support system using a GIS interface. The enhanced SATEEC system was applied to the study watershed to demonstrate how the enhanced system can be effectively used for soil erosion control. All the procedures are fully automated with Avenue, CGI, and database programming; thus the enhanced SATEEC system does not require experienced GIS users to operate the system. This easy-to-operate SATEEC system can be used to identify areas vulnerable to soil loss and to develop efficient soil erosion management plans. 相似文献
20.
水土保持措施及其减水减沙效益分析 总被引：20，自引：17，他引：20
水土流失已经和正在蚕食着人们赖以生存的宝贵的水土资源，如何有效地控制水土流失日益受到社会各界和科学家们的广泛关注。中国在水土保持方面创造了许多颇具特色的水土保持措施，如：生物林草措施、耕作措施和水土保持工程措施。该文总结了目前所采用的主要水土保持措施类型。采用坡度、坡长校正公式将数据转化为具有可比性的量值(标准小区)，定量分析了各种水土保持措施对于减少径流和土壤侵蚀产沙的效果，即治理措施的减水减沙效益，为小流域土壤侵蚀预报、水土保持措施的优化及合理配置、优化土地利用结构等提供参考依据。 相似文献