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| Registros recuperados: 47 | |
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| The increasing number of deteriorating old dams that need renovation or have lost their function make dam removal a viable management option. There are at least four major reasons for dam removal: safety, law and policy, economy, and ecology. Here we discuss 17 Swedish dams that were recently considered for removal. Because dam removal usually causes controversy, dam removal initiatives may succeed, fail, or result in a compromise such as a bypass channel for migrating fish. We identify and discuss three major obstructions to dam removal: funding, cultural-historical values, and threatened species. To facilitate dam removal, the reasons for, and the effects of, dam removal must be carefully explained, and the public and stakeholders must be kept... |
| Tipo: Peer-Reviewed Insight |
Palavras-chave: Controversies; Dam removal; Information; Obstructions; Reservoirs; Rivers; Stakeholder involvement; Sweden. |
| Ano: 2009 |
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| Pittock, Jamie; Australian National University; jamie.pittock@anu.edu.au. |
| Even in the absence of climate change, freshwater ecosystems and the resources they provide for people are under great pressure because of increasing demand for water and declines in water quality. The imminent onset of climate change will exacerbate these impacts, placing even greater pressure on already stressed resources and regions. A plethora of national climate change policies have been adopted that emphasize structural adjustment in the energy sector and increasing carbon sinks. To date, most public debate on water has focused on the direct impacts of climate change on hydrology. However, there is growing evidence that climate change policies themselves may have substantial additional and negative impacts on freshwater resources and ecosystems and... |
| Tipo: Peer-Reviewed Synthesis |
Palavras-chave: Adaptation; Climate change; Conservation; Energy; Governments; Policies; Rivers. |
| Ano: 2011 |
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| Water quality describes the physicochemical characteristics of the water body. These vary naturally with the weather and with the spatiotemporal variation of the water flow, i.e., the flow regime. Worldwide, biota have adapted to the variation in these variables. River channels and their riparian zones contain a rich selection of adapted species and have been able to offer goods and services for sustaining human civilizations. Many human impacts on natural riverine environments have been destructive and present opportunities for rehabilitation. It is a big challenge to satisfy the needs of both humans and nature, without sacrificing one or the other. New ways of thinking, new policies, and institutional commitment are needed to make improvements, both in... |
| Tipo: Peer-Reviewed Synthesis |
Palavras-chave: Catchment scale; Ecosystem processes; Environmental flows; Flow regime; Rivers; Water quality. |
| Ano: 2008 |
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| Roux, Dirk; CSIR; droux@csir.co.za; de Moor, Ferdy; Albany Museum; F.demoor@ru.ac.za; Cambray, Jim; Albany Museum; J.Cambray@ru.ac.za; Barber-James, Helen; Albany Museum; H.James@ru.ac.za. |
| A strategy for assigning priorities in biodiversity conservation was developed for the rivers of the proposed Greater Addo Elephant National Park (GAENP) in South Africa. Due to the limited availability of biological information on the freshwater ecosystems of this area, a desktop approach, supplemented by aerial and land surveys, was used to devise a new river classification typology. This typology incorporated landscape attributes as surrogates for biodiversity patterns, resulting in defined physical "signatures" for each river type. Riverine biodiversity is considered to be conserved by including rivers of each type as defined by the respective signatures. Where options existed, and two or more rivers shared the same signature, a simple procedure was... |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: Greater Addo Elephant National Park; South Africa; Conservation targets; Ecosystem processes; Priority conservation options; Rivers; Signatures of physical pattern; Systematic conservation planning. |
| Ano: 2002 |
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| Mauad,Melina; Miserendino,M. Laura; Risso,Miguel A.; Massaferro,Julieta. |
| ABSTRACT Seven sites were examined in the Challhuaco-Ñireco system, located in the reserve of the Nahuel Huapi National Park, however part of the catchment is urbanized, being San Carlos de Bariloche (150,000 inhabitants) placed in the lower part of the basin. Physico-chemical variables were measured and benthic macroinvertebrates were collected during three consecutive years at seven sites from the headwater to the river outlet. Sites near the source of the river were characterised by Plecoptera, Ephemeroptera, Trichoptera and Diptera, whereas sites close to the river mouth were dominated by Diptera, Oligochaeta and Mollusca. Regarding functional feeding groups, collector-gatherers were dominant at all sites and this pattern was consistent among years.... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Patagonian; Rivers; Macroinvertebrates; Biotic indexes; Water quality. |
| Ano: 2015 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0073-47212015000300348 |
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| Baronas, J. Jotautas; Torres, Mark A.; West, A. Joshua; Rouxel, Olivier; Georg, Bastian; Bouchez, Julien; Gaillardet, Jerome; Hammond, Douglas E.. |
| Solutes derived from the dissolution of silicate minerals play a key role in Earth’s climate via the carbon and other biogeochemical cycles. Silicon (Si) is a unique constituent of silicate minerals and a biologically important nutrient, so tracing its behavior in near-surface environments may provide important insights into weathering processes. However, Si released by weathering is variably incorporated into secondary mineral phases and biota, obscuring signals derived from primary weathering processes. Due to chemical similarities, Germanium (Ge) may help better understand the Si cycle and its relationship to chemical weathering. With this aim, we report new measurements of the concentration and isotopic composition of Ge for both the dissolved and... |
| Tipo: Text |
Palavras-chave: Germanium; Silicon; Isotopes; Rivers; Weathering; Fractionation. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00460/57196/59370.pdf |
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| Dupouy, Cécile; Röttgers, Rüdiger; Tedetti, Marc; Frouin, Robert; Lantoine, François; Rodier, Martine; Martias, Chloe; Goutx, Madeleine. |
| New Caledonia (Southwest Pacific), like all tropical Pacific Island countries, is impacted by weather events, climate change, and local anthropogenic forcing. Strong erosion of particles and dissolved organic matter (DOM) from ultramafic rocks, associated with trace metals dissemination (i.e., nickel, manganese and cobalt), potentially affects lagoon waters and coral reefs surrounding the main island. The CALIOPE (CALedonian Inherent Optical PropErties) cruises were performed along the Eastern Lagoon of New Caledonia (ELNC) (400 km, 13 transects from Bay to open ocean, 51 stations) during contrasted meteorological conditions: a dry period (October 2011), a windy situation (March 2014), and a strong rainy event (March 2016). CDOM absorption and fluorescence... |
| Tipo: Text |
Palavras-chave: Chromophoric dissolved organic matter; Fluorescence; New Caledonia; Tropical Pacific; Lagoons; Biooptics; Phytoplankton; Rivers. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00620/73166/72352.pdf |
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| Martias, Chloe; Tedetti, Marc; Lantoine, Francois; Jamet, Leocadie; Dupouy, Cecile. |
| The eastern lagoon of New Caledonia (NC, Southwest Pacific), listed as a UNESCO World Heritage site, hosts the world's second longest double-barrier coral reef. This lagoon receives river inputs, oceanic water arrivals, and erosion pressure from ultramafic rocks, enriched in nickel (Ni) and cobalt (Co). The aim of this study was to characterize colored dissolved organic matter (CDOM), as well as to determine its main sources and its possible relationships (through the use of Pearson correlation coefficients, r) with biogeochemical parameters, plankton communities and trace metals in the NC eastern lagoon. Water samples were collected in March 2016 along a series of river/lagoon/open-ocean transects. The absorption coefficient at 350 nm (a(350)) revealed... |
| Tipo: Text |
Palavras-chave: CDOM; Fluorescence; Trace metals; Southwest Pacific; Coral reef lagoon; Rivers. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00481/59307/62061.pdf |
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| Dekov, V.m.; Vanlierde, E.; Billstrom, K.; Garbe-schoenberg, C. -d.; Weiss, D. J.; Gatto Rotondo, G.; Van Meel, K.; Kuzmann, E.; Fortin, D.; Darchuk, L.; Van Grieken, R.. |
| Two groundwater-fed river systems (Nete and Demer, Belgium) carry red suspended material that settles on the river bed forming red sediments. The local aquifer that feeds these river systems is a glauconite-rich sand, which provides most of the dissolved Fe to the rivers. The solid component of these systems, i.e., the red suspended material and sediments, has a simple mineralogy (predominantly ferrihydrite), but shows a complex geochemistry pointing out the different processes contributing to the river chemistry: (1) the red sediments have higher transition metal (excluding Cu) and detrital element (e.g., Si, Al, K, Rb, etc.) concentrations than the red suspended matter because of their longer residence time in the river and higher contribution of the... |
| Tipo: Text |
Palavras-chave: Ferrihydrite; Fe-Zn-Sr-Nd-Pb-isotopes; Rivers; Sediments; Suspended matter. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00203/31404/29789.pdf |
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| Bayon, Germain; Vigier, Nathalie; Burton, Kevin W.; Brenot, Agnès; Carignan, Jean; Etoubleau, Joel; Chu, Nan-chin. |
| Hafnium Hf-176/Hf-177 isotope ratio variations in marine records are thought to reflect changes in continental weathering through time, but the behavior of Hf in rivers, and during weathering, is not well understood. Here, we present Hf-176/Hf-177 data for rivers, bedrock, soils, and leaching experiments for the Moselle basin, Vosges, France. These data strongly suggest that the Hf-176/Hf-177 composition of river waters is controlled by preferential dissolution of accessory phases (i.e., apatite, sphene) versus more resistant minerals (e.g., K-feldspar) and linked to the intensity of silicate weathering. Estimates for the global isotopic composition of riverine Hf suggest that the ocean Hf budget may be dominated by river input, and variations seen in... |
| Tipo: Text |
Palavras-chave: Ocean chemistry; Silicate weathering; Rivers; Hafnium isotopes. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-2078.pdf |
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| Rodríguez, A.J.; Arpajón, I.; Castaño, Z.; Marsán, R.; Lugo, D.; Roevros, N.; Chou, L.; Rojas, N.; Heydrich, M.. |
| The Almendares River constitutes the most important superficial stream in Cuban capital, that finishes in the Metropolitan Park of Havana, which is an entertaining centre. The objective of this work is to determine the presence of toxic inorganic pollutants in the Almendares River water. 10 samplings were carried out from June 2003 to May 2004 in 14 stations established along the last 10 km of the river and 3 tributaries. The quantification of nitrates, nitrites and ammonium was done by spectrophotometric methods The concentration of heavy metals in the dissolved and particulate phase was determined by atomic emission spectrometry. The total microbial charge was determined by epifluorescency. Were found high levels of ammonium and nitrites, as well as high... |
| Tipo: Proceedings Paper |
Palavras-chave: Rivers; Freshwater pollution; Heavy metals; Rivers; Heavy metals; Http://aims.fao.org/aos/agrovoc/c_6617; Http://aims.fao.org/aos/agrovoc/c_2223. |
| Ano: 2006 |
URL: http://hdl.handle.net/1834/2086 |
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| Registros recuperados: 47 | |
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