نتایج جستجو برای: stream sediment

تعداد نتایج: 93248  

2008
Fabrício Barreto Fernando Rogério Carvalho

Following behaviour among Neotropical stream fishes have been scarcely reported. This type of feeding association was observed in a small stream in the upper rio Paraná system between the catfish, Aspidoras fuscoguttatus, acting as a nuclear species, and Knodus moenkhausii, Poecilia reticulata, and Astyanax altiparanae as follower species. Aspidoras fuscoguttatus individuals dug in the bottom d...

2010
Rajith Mukundan

Water quality modeling efforts for developing total maximum daily loads often use geographical information system data of varying quality in watershed-scale models and have shown varying impacts on model results. Several streams in the southern Piedmont are listed for sediment total maximum daily loads. The objective of this study was to test the effect of spatial resolution of soil data on the...

Journal: :Applied and environmental microbiology 2008
Steven A Wakelin Matt J Colloff Rai S Kookana

We investigated the effects of wastewater treatment plant (WWTP) discharge on the ecology of bacterial communities in the sediment of a small, low-gradient stream in South Australia. The quantification of genes involved in the biogeochemical cycling of carbon and nitrogen was used to assess potential impacts on ecosystem functions. The effects of disturbance on bacterial community structure wer...

Journal: :Archives of environmental contamination and toxicology 2001
J S Khim K T Lee K Kannan D L Villeneuve J P Giesy C H Koh

Sediment and water samples collected from 32 locations in Ulsan Bay and adjacent inland areas were analyzed for polycyclic aromatic hydrocabons (PAHs), nonylphenol (NP), octylphenol (OP), bisphenol A (BPA), organochlorine (OC) pesticides (HCB, HCHs, CHLs, and DDTs), and polychlorinated biphenyls (PCBs) to characterize their spatial distribution and contamination status. PAHs were detected in ne...

2017
Xin Chen Yong Li Genfa Chen Fujun Wang Liuchao Qiu

On the basis of advanced concentration and velocity profiles above a mobile seabed, an instantaneous analytical model is derived for sediment transport in asymmetric oscillatory flow. The applied concentration profile is obtained from the classical exponential law based on mass conservation, and asymmetric velocity profile is developed following the turbulent boundary layer theory and the asymm...

Journal: :جغرافیا و مخاطرات محیطی 0
محمدحسین رضائی مقدم معصومه رجبی رسول دانشفراز منصور خیری زاده

1. introduction floods are among earth's most common and most destructive natural hazards. floods create geomorphic hazards via changes in sediment transport and channel configuration (e.g. channel width, lateral migration, planform changes, etc). in this context, floodplain zoning and its application in spatial planning is important in non- structural measures in order to reducing flood damage...

2006
Brett C. Eaton Michael Church Tim R. H. Davies

A simple analytic model is presented relating local sediment transport capacity to variance in the transverse shear stress distribution in a stream channel. The model is used to develop a physically based conceptual model for the initiation of meandering in straight, bedloaddominated streams as a result of a feedback mechanism. The feedback maximizes the crosssectional shear stress variance and...

2009
BRET C. HARVEY JASON L. WHITE RODNEY J. NAKAMOTO

—Elevated fine-sediment inputs to streams can alter a variety of conditions and processes, including the amount of fine sediment stored in riffles. We sought to measure the influence of deposited fine sediment on the survival and growth of juvenile rainbow trout Oncorhynchus mykiss (106–130 mm fork length) using a field experiment that included 18 enclosures in riffles of a small northwestern C...

2013
Elisabeth Pohlon Adriana Ochoa Fandino Jürgen Marxsen

Droughts are among the most important disturbance events for stream ecosystems; they not only affect stream hydrology but also the stream biota. Although desiccation of streams is common in Mediterranean regions, phases of dryness in headwaters have been observed more often and for longer periods in extended temperate regions, including Central Europe, reflecting global climate change and enhan...

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