Response of fish communities in rivers subjected to a high sediment load

Erosion and sediment yield are a significant problem in the Guadalquivir River basin. Such phenomena are largely driven by a land use devoted to intensive cultivation of olive trees, with a large socioeconomic influence in Andalusia. This sediment overload in rivers causes serious impacts on all fluvial ecosystem components.In this study we assess the chronic effect of sediment yield on fish communities at 104 river sites located in two different sub-catchments – the Bembézar and Guadajoz rivers – both with different lithological composition and erosion rates. Sediment yield was estimated using a semi-quantitative Factorial Score Model (FSM), developed specifically for Spanish rivers. The fish populations of both basins were evaluated in composition and abundances by the study of Fernández-Delgado et al., 2014. The influence of sediment yield on the fish community was analyzed using General Additive Models.The sediment yield was higher in the Guadajoz basin (921 T/Km2 per year) than in Bembézar (701 T/Km2 per year). In the former, fish communities were poorer in both fish density and diversity, with Luciobarbus sclateri as the only substantially present species and a significant relationship between sediment yield and load, and fish density. In contrast, in the Bembézar basin, sediment yield was correlated with total fish density, including Luciobarbus sclateri, Pseudochondrostoma willkommii, Cobitis paludica, Iberochondrostoma lemmingii, Anaecypris hispanica, and Cyprinus carpio. Intermediate values of sediment yield led to maximum densities, while those higher decreased the density of these species.     

Probabilistic analysis of soil‐structure interaction effects on the seismic performance of structures

This paper revisits the phenomenon of dynamic soil‐structure interaction (SSI) with a probabilistic approach. For this purpose, a twofold objective is pursued. First, the effect of SSI on inelastic response of the structure is studied considering the prevailing uncertainties. Second, the consequence of practicing SSI provisions of the current seismic design codes on the structural performance is investigated in a probabilistic framework. The soil‐structure system is modeled by the sub‐structure method. The uncertainty in the properties of the soil and the structure is described by random variables that are input to this model. Monte Carlo sampling analysis is employed to compute the probability distribution of the ductility demand of the structure, which is selected as the metrics for the structural performance. In each sample, a randomly generated soil‐structure system is subjected to a randomly selected and scaled ground motion. To comprehensively model the uncertainty in the ground motion, a suite of 3269 records is employed. An extensive parametric study is conducted to cover a wide range of soil‐structure systems. The results reveal the probability that SSI increases the ductility demand of structures designed based on the conventional fixed‐based assumption but built on flexible soil in reality. The results also show it is highly probable that practicing SSI provisions of modern seismic codes increase the ductility demand of the structure. Copyright © 2016 John Wiley & Sons, Ltd.     

河南新郑—太康断裂东段土壤气体地球化学特征

土壤气浓度测量能够揭示断裂位置和活动特征。 由于河南新郑—太康断裂北西向隐伏断裂带空间定位精度有待提高, 以及2016年5月该区出现地下逸出气异常的宏观现象, 在太康县西近垂直于断裂走向布设了一条长约13 km的NE—NNE走向的地球化学观测剖面, 用于分析隐伏断层浅层位置及其与地下逸出气宏观异常的关系。 观测结果表明: 该剖面的异常段与该区浅层地震勘探显示的断裂带地表出露位置相吻合, 其中Rn体积活度和H₂、 CO₂浓度异常揭示出南段有4条断层, 北段有2条断层, 且均具有高角度特征, 南段的CO₂浓度异常区与地下逸出气宏观异常位置相符, 但代表构造特征的Rn体积活度和H₂浓度没有出现异常, 认为与构造关系不密切。     

城郊"水土流失带"的结构、特征与治理模式研究

从生态学和地理学的角度提出“水土流失带”的概念,及其在城市边缘地区的分布,剖析了它的空间结构,物质组成结构,指出其域界范围,宽度、“环状”;分布,垂直结构特征及物质组成结构的多元性。     

Soil erosion modelled with USLE and PESERA using QuickBird derived vegetation parameters in an alpine catchment

The focus of soil erosion research in the Alps has been in two categories: (i) on-site measurements, which are rather small scale point measurements on selected plots often constrained to irrigation experiments or (ii) off-site quantification of sediment delivery at the outlet of the catchment. Results of both categories pointed towards the importance of an intact vegetation cover to prevent soil loss. With the recent availability of high-resolution satellites such as IKONOS and QuickBird options for detecting and monitoring vegetation parameters in heterogeneous terrain have increased. The aim of this study is to evaluate the usefulness of QuickBird derived vegetation parameters in soil erosion models for alpine sites by comparison to Cesium-137 (Cs-137) derived soil erosion estimates. The study site (67 km²) is located in the Central Swiss Alps (Urseren Valley) and is characterised by scarce forest cover and strong anthropogenic influences due to grassland farming for centuries. A fractional vegetation cover (FVC) map for grassland and detailed land-cover maps are available from linear spectral unmixing and supervised classification of QuickBird imagery. The maps were introduced to the Pan-European Soil Erosion Risk Assessment (PESERA) model as well as to the Universal Soil Loss Equation (USLE). Regarding the latter model, the FVC was indirectly incorporated by adapting the C factor. Both models show an increase in absolute soil erosion values when FVC is considered. In contrast to USLE and the Cs-137 soil erosion rates, PESERA estimates are low. For the USLE model also the spatial patterns improved and showed “hotspots” of high erosion of up to 16 t ha⁻¹ a⁻¹. In conclusion field measurements of Cs-137 confirmed the improvement of soil erosion estimates using the satellite-derived vegetation data.     

基于遥感技术的开都河下游绿洲区土壤盐渍化动态监测研究

以3期遥感图像为数据源,经图像处理,并结合野外考察,建立解译标志进行遥感解译。结果表明,开都河下游绿洲区的盐渍化土地面积呈先增加后减少趋势,盐渍化程度呈先加重后减轻趋势;盐渍化土壤主要分布在开都河沿岸低洼地和博斯腾湖湖滨地区及其北岸清水沟、曲惠渠、乌什塔拉渠两岸附近;盐渍化的形成与研究区地形地貌、地下水以及干旱的气候条件密切相关,人类农业活动对盐渍化土壤形成具有重要作用。     

Konzepte zur Mobilitätsabschätzung von Schadstoffen in Boden- und Abfallmaterialien

Concepts for the Evaluation of Contaminant Mobility in Soil and Waste Materials Elution tests (S4, pH_stat, and SDS test) are presented, enabling the evaluation of the mobility of hydrophilic/hydrophobic and inorganic/organic contaminants in soil and waste materials. While elution tests for estimation of the mobilization potential of hydrophilic substances are performed following the pH_stat method, for hydrophobic species surfactant-containing eluents are used. The individual parameters of the elution process are selected assuming a "worst-case" scenario. In principle, because of economic reasons, detailed analytical investigations should be preceded by relevant screening tests.     

Urease-Hemmtest für wirkungsbezogene Untersuchungen der Bindungsformen von Kupfer in Wässern und Bodeneluaten

Urease Inhibition Test for Effect-related Investigations of Copper Speciation in Water and Soil Extracts In 80 different water samples, the inhibition effect of cupric ions was measured by application of a simple urease inhibition test. In relation to the total copper concentration, the inhibition permits an effect-related classification of drinking water, rain water, spring water, surface water, leakage water, wastewater, and soil extracts. Drinking water contains high parts of cupric ions in the free hydrated form. Their copper content results in high urease inhibition and is caused by using copper pipes in house plumbing. In leakage water, wastewater, and soil extracts, cupric ions are mainly complexed by organic compounds in the sample matrix. Hence, the inhibition effects are low. In soil extracts, the urease inhibition increased after an UV-decomposition procedure, but a decreasing effect was observed for a surface and a drinking water sample, respectively. The chemical oxygen demand and UV-absorbance at 255 nm measured before and after the procedure were correlated to the content of organic compounds, i.e., humic acid. In most samples, the organic matrix was not decomposed completely. The oxidizing decomposition apparently forms further complexing agents, which suppress the inhibition effect of cupric ions. In the rain water samples investigated, the content of organic compounds depended on rain intensity. The chemical oxygen demand and UV-absorbance, respectively, were low for rain water collected during strong rain periods and increased with decreasing rain intensity. The rain water trickled over sheet-lead roof showed an increase of urease inhibition compared with the simultaneously collected rain. Consequently, a decomposition of organic matrix could be demonstrated in rain water by use of the urease inhibition test.