نتایج جستجو برای: rivers

تعداد نتایج: 19001  

Journal: :The Science of the total environment 2010
Karen A Blocksom David M Walters Terri M Jicha James M Lazorchak Theodore R Angradi David W Bolgrien

Great rivers of the central United States (Upper Mississippi, Missouri, and Ohio rivers) are valuable economic and cultural resources, yet until recently their ecological condition has not been well quantified. In 2004-2005, as part of the Environmental Monitoring and Assessment Program for Great River Ecosystems (EMAP-GRE), we measured legacy organochlorines (OCs) (pesticides and polychlorinat...

Journal: :Remote Sensing 2017
Sarah Praskievicz Emily Buege

The physical characteristics of river systems exert significant control on the habitat for aquatic species, including the distribution of in-stream channel habitat units. Most previous studies on channel habitat units have focused on midlatitude rivers, which differ in several substantive ways from tropical rivers. Field delineation of channel habitat units is especially challenging in tropical...

2017
D. Mark Powell

Dryland alluvial rivers vary considerably in character. In terms of processes, high energy, sediment-laden flash floods in upland rivers contrast dramatically with the low sediment loads and languid flows of their lowland counterparts while from a form perspective, the unstable wide, shallow and sandy braid plains of piedmont rivers are quite different from the relatively stable, narrow, deep a...

2018
Timothy D Counihan Ian R Waite Andrew F Casper David L Ward Jennifer S Sauer Elise R Irwin Colin G Chapman Brian S Ickes Craig P Paukert John J Kosovich Jennifer M Bayer

Understanding trends in the diverse resources provided by large rivers will help balance tradeoffs among stakeholders and inform strategies to mitigate the effects of landscape scale stressors such as climate change and invasive species. Absent a cohesive coordinated effort to assess trends in important large river resources, a logical starting point is to assess our ability to draw inferences ...

Journal: :Anais da Academia Brasileira de Ciencias 2011
Davi G F Cunha Doron Grull Murilo Damato José R C Blum Sergio Eiger José E I Lutti Pedro C S Mancuso

The management of urban water resources plays an important role for developing countries. The Tietê and Pinheiros Rivers (São Paulo, Brazil) are affected by domestic and industrial effluents and by the diffuse pollution. This research aimed to quantify 134 variables in the water of Tietê and Pinheiros Rivers (approximately 7,200 and 6,600 analyses, respectively) from August 2007 to December 200...

Journal: :The Science of the total environment 2006
John Hilton Matthew O'Hare Michael J Bowes J Iwan Jones

Although the process of eutrophication is reasonably well understood in lakes, there is currently no conceptual understanding of how eutrophication develops in rivers. This issue is addressed here. A review of the main processes controlling the development of eutrophication in lakes has been carried out as a precursor to considering the effect in rivers. The importance of hydraulic flushing in ...

2014
Gabriel de Souza da Costa e Silva Fábio Fernandes Roxo Ricardo Britzke Claudio Oliveira

A new species of Pseudancistrus is described from the Tapajós Basin, and assigned to the P. barbatus group by having hypertrophied odontodes along the snout and lacking evertible cheek plates. The new species is distinguished from other species in that group (P. barbatus, P. corantijniensis, P. depressus and P. nigrescens) by its pattern of spots, length and color of snout odontodes, greater he...

2016
Krzysztof Szoszkiewicz Anna Budka Karol Pietruczuk Dariusz Kayzer Daniel Gebler

The variation of a number of parameters characterizing aquatic plant assemblages in rivers across a wide trophic gradient was investigated to evaluate their usefulness for a Polish national river monitoring system. Analyses were conducted at 100 sites included in the national river monitoring system, representing a uniform river type, i.e., small- and medium-sized lowland rivers with a sandy su...

Journal: :Environmental Conservation 1986

2012
Richard Dawkins

s for these talks are published in the GSA Abstracts With

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