Comparative ecophysiology of active zoobenthic filter feeding, essence of current knowledge     

H. U. Riisgrd  P. S. Larsen 《Journal of Sea Research》2000,44(3-4)

The present contribution gives an overview of current knowledge of a comprehensive and steadily growing research field. The first section deals with water pumping and particle retention mechanisms in ciliary and muscular filter feeders. The second section examines the biological filter pumps in order to assess adaptation to the environment. Filter-feeding benthic invertebrates have evolved filter pumps to solve common basic problems. This has led to a large degree of similarity between otherwise distant standing species, which makes comparative studies interesting and important. The present review of zoobenthic filter feeding aims at accentuating such recognition.  相似文献   

江西省万安水库对氮、磷营养盐的滞留效应   总被引：6，自引：0，他引：6  

胡春华  周文斌  钟夏莲  王毛兰 《湖泊科学》2011,23(1):35-39

以江西省万安水库为研究对象,于2007-2009年丰、枯水期对水库进行了人库、出库水样采集,研究了万安水库对氮、磷营养盐的滞留效应.结果表明,万安水库对氮、磷营养盐存在显著滞留作用.DIN浓度和输送通量整体均表现为入库>出库,受径流量季节变化的影响.不同时期DIN的滞留情况整体表现为枯水期<丰水期;TP浓度和输送通量整...  相似文献   

Performance Evaluation of a Full‐Scale Constructed Wetland for Treating Stormwater Runoff     

《洁净——土壤、空气、水》2017,45(11)

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Estimating the sediment trap efficiency of intermittently dry reservoirs: lessons from the Kruger National Park,South Africa          下载免费PDF全文

Bastian Reinwarth  Edward S. Riddell  Christoph Glotzbach  Jussi Baade 《地球表面变化过程与地形》2018,43(2):463-481

The assessment of sediment yield from reservoir siltation requires knowledge of the reservoir's sediment trap efficiency (TE). Widely used approaches for the estimation of the long‐term mean TE rely on the ratio of the reservoir's storage capacity (C) to its catchment size (A) or mean annual inflow (I). These approaches have been developed from a limited number of reservoirs (N ≤ 40), most of them located in temperate climate regions. Their general applicability to reservoirs receiving highly variable runoff such as in semi‐arid areas has been questioned. Here, we examine the effect of ephemeral inflow on the TE of 10 small (≤ 280 × 10³ m³), intermittently dry reservoirs located in the Kruger National Park. Fieldwork was conducted to determine the storage capacity of the reservoir basins. The frequency and magnitude of spillage events was simulated with the daily time step Pitman rainfall–runoff model. Different runoff scenarios were established to cope with uncertainties arising from the lack of runoff records and imperfect input data. Scenarios for the relationship between water and sediment discharge were created based on sediment rating curves. Taking into account uncertainties in hydrological modelling, uncertainties of mean TE estimates, calculated from all scenarios (N = 9), are moderate, ranging from ±6 to ±11% at the 95% confidence level. By comparison, estimating TE from the storage capacity to catchment area (C/A) ratio induces high uncertainty (ranges of 35 to 65%), but this uncertainty can be confined (15 to 33%) when the latter approach is combined with hydrological modelling. Established methods relying on the storage capacity to mean annual inflow (C/I) ratio most probably lead to an overestimation of the TE for the investigated reservoirs. The approach presented here may be used instead to estimate the TE of small, intermittently dry reservoirs in semi‐arid climate regions. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

水库对河流营养盐滞留效应研究进展   总被引：14，自引：5，他引：9  

冉祥滨  于志刚  姚庆祯  陈洪涛  米铁柱  姚鹏 《湖泊科学》2009,21(5):614-622

综述了国内外水库对河流营养盐滞留效应的主要进展,尽管在大型水库是否显著改变原有河流输送营养盐的问题上存在诸多争议,反映在滞留效率的估算上,存在前后矛盾的结果,但大量的文献仍支持筑坝显著改变了河流原有输送营养盐的特性,并对下游、河口产生深远的影响.本文将"滞留"的主要过程分为泥沙过滤作用和生物过滤作用,并列举了若干经典的估算滞留效率的方法和部分水库对营养盐的滞留效率.  相似文献   

土−水特征曲线测量过程中孔隙分布的演化规律探讨     

牛庚  邵龙潭  孙德安  韦昌富  郭晓霞  徐华 《岩土力学》2020,41(4):1195-1202

测量了在宽广吸力范围内原状样和压实样的脱湿持水曲线,对比分析了单双峰结构持水性能的差异;并利用压汞试验测试两种土样在脱湿过程的孔隙分布,分析了两者的差异并探讨了脱湿过程孔隙的演化规律;在考虑收缩变形的基础上,基于孔隙分布曲线确定了土?水特征曲线的基本参数。试验结果表明：原状样在宽广吸力范围内基本上呈单峰孔隙结构;饱和压实样具有单峰孔隙结构,随着吸力的增加,双峰结构越来越明显,当吸力达到很大时,演化成完全双峰孔隙结构。原状样的持水曲线为经典的S形,而压实样的持水曲线在过渡段出现了水平台阶状;低吸力段,压实样的持水曲线低于原状样,而高吸力段,两者的持水曲线基本重合。基于孔隙分布曲线确定了控制持水曲线进气值和残余值的孔径,并计算出对应的吸力值,其值更符合实际物理意义。  相似文献   

半封闭大棚实验下广州市植被滞尘光谱特征分析     

张晨  周霞  李勇  杨骥  李林 《热带地理》2020,40(2):266-277

基于广州市常见的绿化植物,采用高光谱遥感技术,通过设计半封闭的大棚实验方案,探讨了滞尘污染下不同植物叶片的光谱特征,结果表明：1）滞尘时间是影响绿化植物累积滞尘量的一个重要因子,滞尘量随着时间的增加而增加,但达到饱和之后会呈减少的趋势。2）在可见光波段,受叶面尘影响,叶片光谱反射率升高,且随滞尘量的增加而升高;在近红外波段则相反,光谱反射率随滞尘量的增加而降低。3）叶面尘对植物叶片的光谱特征参数具有直接或间接的影响,其中滞尘量与植物的三边位置无关,与归一化植被指数NDVI呈负相关关系,且不同植物的NDVI受叶面尘影响的程度不同,从大到小依次为：朱蕉>红花檵木>金叶榕。文章设计的半封闭大棚实验方案为植物滞尘效应的长时间可持续性研究提供了新思路。  相似文献   

Methodology and software solutions for multicriteria evaluation of floodplain retention suitability     

Rico Vogel 《制图学和地理信息科学》2016,43(4):301-320

Extreme flood events often have adverse effects for people living near or within areas at risk. Reactivating morphological river floodplains for flood retention measures can substantially reduce flood wave peaks and the negative flooding consequences. This article accordingly focuses on a methodology for identifying suitable locations for such measures by spatial multicriteria evaluation (MCE). Compromise programming (CP) and the analytic hierarchy process (AHP) are core methodological components. Furthermore, this methodology is based on impact analysis and draws on expert knowledge. This article also deals with software tools that support the operationalization of methodological components. Data harmonization algorithms are implemented as geoprocessing tools. Both CP and AHP are designed as software providing graphical user interfaces (GUIs). While an extension integrates CP into a geoinformation system, AHP is realized as a web application enabling participation of expert practitioners. The methodological components are operationalized through an example on the floodplains of the German river Elbe.  相似文献   

采用滞留水量的洪水淹没计算     

赵骞  邓轶  李东阳  吴志宜  陈文志 《测绘科学》2016,41(10):74-77

针对城市地区暴雨致洪问题以及快速、科学分析处理洪涝灾害的应急测绘保障服务工作要求,该文提出了一种基于滞留水量的洪水淹没计算分析方法。采用美国水土保持局提出的模型计算降雨产水量,结合区域排水能力,河网、湖泊、水库调蓄水能力和境外来水量,实现区域滞留水量计算分析;在此基础上,利用数字高程模型数据和洪水淹没分析方法,实现区域淹没水深和淹没范围计算分析。研究区实例计算验证结果表明:该方法能够满足应急测绘保障服务工作要求,快速为相关部门洪涝灾害分析提供科学决策依据。  相似文献   

Formulation of a three‐dimensional constitutive model for unsaturated soils incorporating mechanical–water retention couplings     

Martí Lloret‐Cabot  Marcelo Sánchez  Simon J. Wheeler 《国际地质力学数值与分析法杂志》2013,37(17):3008-3035

Wheeler, Sharma and Buisson proposed an elasto‐plastic constitutive model for unsaturated soils that couples the mechanical and water retention behaviours. The model was formulated for isotropic stress states and adopts the mean Bishop's stress and modified suction as stress state variables. This paper deals with the extension of this constitutive model to general three‐dimensional stress conditions, proposing the generalized stress–strain relationships required for the numerical integration of the constitutive model. A characteristic of the original model is the consideration of a number of elasto‐plastic mechanisms to describe the complex behaviour of unsaturated soils. This work presents the three‐dimensional formulation of these coupled irreversible mechanisms in a generalized way including anisotropic loading. The paper also compares the results from the model with published experiments performed under different loading conditions. The response of the model is very satisfactory in terms of both mechanical and water retention behaviours. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献