124,355 research outputs found
Summer CO2 evasion from streams and rivers in the Kolyma River basin, north-east Siberia
No full textInland water systems are generally supersaturated in carbon dioxide (CO2) and are increasingly recognized as playing an important role in the global carbon cycle. The Arctic may be particularly important in this respect, given the abundance of inland waters and carbon contained in Arctic soils; however, a lack of trace gas measurements from small streams in the Arctic currently limits this understanding.We investigated the spatial variability of CO2 evasion during the summer low-flow period from streams and rivers in the northern portion of the Kolyma River basin in north-eastern Siberia. To this end, partial pressure of carbon dioxide (pCO2) and gas exchange velocities (k) were measured at a diverse set of streams and rivers to calculate CO2 evasion fluxes.
We combined these CO2 evasion estimates with satellite remote sensing and geographic information system techniques to calculate total areal CO2 emissions. Our results show that small streams are substantial sources of atmospheric CO2 owing to high pCO2 and k, despite being a small portion of total inland water surface area. In contrast, large rivers were generally near equilibrium with atmospheric CO2. Extrapolating our findings across the Panteleikha-Ambolikha sub-watersheds demonstrated that small streams play a major role in CO2 evasion, accounting for 86% of the total summer CO2 emissions from inland waters within these two sub-watersheds. Further expansion of these regional CO2 emission estimates across time and space will be critical to accurately quantify and understand the role of Arctic streams and rivers in the global carbon budget
Rivers of the Anthropocene /
No full text"This exciting volume presents the work and research of the Rivers of the Anthropocene Network, an international collaborative group of scientists, social scientists, humanists, artists, policy makers, and community organizers working to produce innovative transdisciplinary research on global freshwater systems. In an attempt to bridge disciplinary divides, the essays in this volume address the challenge in studying the intersection of biophysical and human sociocultural systems in the age of the Anthropocene. Featuring contributions from authors in a rich diversity of disciplines--from toxicology to archaeology to philosophy--this book is an excellent resource for students and scholars studying both freshwater systems and the Anthropocene"--Provided by publisher.Includes bibliographical references and index.Anthropocenes : a fractured picture / Jason M. Kelly -- The importance of ecosystem service-based approaches to management of Anthropocene riverscapes / Andy Large, David Gilvear, and Eleanor Starkey -- Political ecology in the Anthropocene : a case study of irrigation management in the Blue Nile basin / Sina Marx -- Rivers at the end of the end of nature : ethical trajectories of the Anthropocene grand narrative / Celia Deane-Drummond -- Rivers, scholars, and society : a situation analysis / Kenneth S. Lubinski and Martin Thoms -- An Anthropocene landscape : drainage transformed in the English fenland / Jan Zalasiewicz, Mark Williams, and Dinah Smith -- A western European river at the Anthropocene : the Seine (1880-2010) / Michel Meybeck and Laurence Lestel -- Anthropocene rivers : a historical examination of ideas and agency / Philip Scarpino -- The Great Tyne Flood of 1771 : community responses to an environmental crisis in the early Anthropocene / Helen Berry -- Engineering an island city- state : a 3D ethnographic comparison of the Singapore River and Orchard Road / Stephanie C. Kane -- Decoding the river : artists and scientists reveal the water system of the White River / Mary Miss and Tim Carter -- What is a river? : the Chicago River as hyperobject / Matt Edgeworth and Jeffrey Benjamin."This exciting volume presents the work and research of the Rivers of the Anthropocene Network, an international collaborative group of scientists, social scientists, humanists, artists, policy makers, and community organizers working to produce innovative transdisciplinary research on global freshwater systems. In an attempt to bridge disciplinary divides, the essays in this volume address the challenge in studying the intersection of biophysical and human sociocultural systems in the age of the Anthropocene. Featuring contributions from authors in a rich diversity of disciplines--from toxicology to archaeology to philosophy--this book is an excellent resource for students and scholars studying both freshwater systems and the Anthropocene"--Provided by publisher.Print version record and CIP data provided by publisher; resource not viewed.JSTO
Fluvial contributions of nutrient salts, dissolved trace elements and organic carbon to the sea by pristine temperate rivers (SW Europe).
No full textBernárdez, P., Ospina-Alvarez, N., Caetano, M., & Prego, R. (2013). Fluvial contributions of nutrient salts, dissolved trace elements and organic carbon to the sea by pristine temperate rivers (SW Europe). Environmental Chemistry, 10(1), 42–53. doi:http://dx.doi.org/10.1071/EN1212
Temporal and spatial trends for trace metals in streams and rivers across Sweden (1996-2009)
No full textLong term data series (1996 through 2009) for trace metals were analyzed from a large number of streams and rivers across Sweden varying in tributary watershed size from 0.05 to 48 193 km(2). The final data set included 139 stream sites with data for arsenic (As), cobalt (Co), copper (Cu), chromium (Cr), nickel (Ni), lead (Pb), zinc (Zn), and vanadium (V). Between 7% and 46% of the sites analyzed showed significant trends according to the seasonal Kendall test. However, in contrast to previous studies and depositional patterns, a substantial portion of the trends were positive, especially for V (100%), As (95%), and Pb (68%). Other metals (Zn and Cr) generally decreased, were mixed (Ni and Zn), or had very few trends (Co) over the study period. Trends by region were also analyzed and some showed significant variation between the north and south of Sweden. Regional trends for both Cu and Pb were positive (60% and 93%, respectively) in the southern region but strongly negative (93% and 75 %, respectively) in the northern region. Kendall's tau coefficients were used to determine dependence between metals and potential in-stream drivers including total organic carbon (TOC), iron (Fe), pH, and sulphate (SO(4)(2-)). TOC and Fe correlated positively and strongly with As, V, Pb, and Co while pH and SO(4)(2) generally correlated weakly, or not at all with the metals studied
Phytoplankton dynamics of the feeder rivers of the Humber estuary
No full textThe effect of environmental conditions upon the growth, production and development of river phytoplankton was investigated for the feeder rivers to the Humber Estuary. The study was part of the Land Ocean Interaction Study LOIS) and focused upon the Rivers Trent and Yorkshire Ouse. The influence of physical, chemical and biological factors upon phytoplankton development were measured through routine fieldwork and laboratory analyses. During fieldwork measurements were collected which complemented measurements collected by LOIS colleagues. Data collected in this study included phytoplankton species composition, density and biomass and is situ rates of growth and production. In situ rates of loss through grazing and respiration were also measured. Laboratory investigations concentrated upon the effects of Ught and temperature upon dominant phytoplankton species and were developed to complement fieldwork. The project focused around four main aims. These were basically to assess the size and composition of phytoplankton maxima in the Trent and Ouse, measure in situ rates of growth and production, estimate losses from grazing and to develop models, using the data collected to assess the effect of environmental conditions upon phytoplankton development and autochthonous carbon in the Humber Estuary. The results showed that phytoplankton dynamics in the Trent and Ouse were controlled primarily by discharge, light and temperature. During spring, when conditions were favourable for growth, rapid phytoplankton growth and maximum rates of production were observed. However, spring floods often interrupted die large phytoplankton populations which developed. Other factors such as grazing and sedimentation were also considered as potentially important in the loss of phytoplankton. The turbid nature of the rivers resulted in a fine balance between photosynflietic gain and respirational loss. This temporal change in environmental conditions resulted in a temporal waxing and waning of the phytoplankton. This in turn had an impact upon the seasonality of the flux of autochthonous carbon to the Humber Estuary. Laboratory investigations and development of a photosynthetic model confirmed the importance of light and temperature upon phytoplankton development in these rivers. In terms of phytoplankton growth and production and the flux of autochthonous carbon, the Trent and Ouse were found to be typical of many other European rivers. The study highlighted the importance of the Trent as a source of autochthonous carbon to the Humber Estuary
An Interdisciplinary Approach to Assessing, Planning and Managing Urban Rivers in the context of Greater London
No full textPhDUrban rivers present complex management challenges due to the combined natural and
anthropocentric factors affecting developed catchments. Planning urban river
rehabilitation strategies and measures in parallel with green infrastructure initiatives
requires the combined expertise of multi-disciplinary partnerships, encompassing river
science and landscape engineering plus community engagement, to deliver integrated
and sustainable outcomes. This thesis takes an interdisciplinary approach to investigate
the assessment and management of urban rivers, focusing specifically upon the planning
of integrated restoration projects for River Thames tributaries within Greater London.
Comparisons of restored and unrestored sites on London tributary rivers at the reachand
catchment-scale explore the versatility of the Urban River Survey method for
assessing and communicating contrasts in the bio-physical condition and
engineering:habitat associations of heavily modified rivers. A trial of the Ecosystem
Services Assessment method for urban river restorations indicates the strengths and
limitations of this approach and areas of research need.
Urban river governance investigations and a review of changes in restoration practices
over time confirm a decreasing emphasis on channel control and progressively lighter
engineering, plus a greater social focus with urban river management becoming
increasingly driven by awareness of the symbiosis between rivers and local
communities. In some London boroughs partner organisations are developing new links
through sustainable development objectives, but connections are geographically
inconsistent and typically dependent upon key advocates.
Findings indicate that integrated planning can facilitate interdisciplinary processes
through the identification of cross-cutting themes (e.g. climate change) and open
knowledge exchange when delivered with appropriate levels of detail. While some
disciplinary boundaries are necessary (to define project scope and for task
management), socio-ecological benefits may be achieved when these are flexible,
permeable and managed responsively in relation to simple overarching goals; and by
allowing time for different kinds of knowledge to merge and stimulate new creative and
integrated interpretations
A geomorphological framework for providing ecosystem services in lowland rivers
No full textThe publication of the Millennium Ecosystem Assessment (MA, 2005) has generated widespread scientific debate regarding the importance of linkages between ecosystems and human well-being. An ecosystem services approach has presented many challenges during its early stages of development; fundamentally the ability to classify and value an ecosystem and its services. By its complex nature, ecosystem service research requires an interdisciplinary approach.The thesis focuses on the role of geomorphology as a means to providing a framework for delivering ecosystem services in lowland rivers. The framework introduces a reach-scale analysis of how geomorphological functions (GF) help provide a platform for bio-physical interactions that deliver multiple ecosystem services in lowland rivers. The analysis will assess the influence of geomorphological functions (GF) in providing ecosystem services.Understanding the links between „ecosystem services? and the functioning of ecosystems to human welfare is critical for a wide range of decision-making contexts (Fisher et al., 2008). River restoration provides a useful and practical technique for placing monetary costs to the functions that characterise geomorphologically diverse rivers, whilst allowing for a spatial understanding on how physical characteristics impact the delivery of multiple ecosystem services. Case studies help reveal other direct and indirect benefits associated with riverine environments
Sediment-macrophyte relationships in lowland English rivers: using macrophytes for biological assessment
No full textPhDA study of the relationship between submerged-rooted aquatic macrophytes and the
chemical and physical characteristics of sediments in lowland British rivers is described.
The focus of the research is the spatial variability of nutrient concentrations in river
sediments and the preferences of particular macrophyte species for different sediment
types. This information is required to further develop the use of macrophytes in the
biological assessment of rivers. Sediment samples were collected from beneath
macrophyte stands and unvegetated areas of the riverbed in 17 rivers. The sediment
samples were analysed for total and inorganic phosphorus, total nitrogen, organic carbon, organic matter and silt-clay content. Data on water chemistry flow regimes, channel
geometry and macrophyte habitat were also collected.
Sediments were found to exhibit a high degree of variability both within 100m sites and between the different rivers, particularly with respect to phosphorus concentrations. There
were relationships between sediment concentrations of total and inorganic phosphorus
and between concentrations of total nitrogen, organic carbon and organic matter. No clear
relationships between mean values for sediment parameters and either water column
nutrient concentrations or flow regime were apparent. The significance of the sediment
variables as a control on macrophyte community structure was investigated through the use of canonical ordination and discriminant analysis. Macrophyte species showed broad
tolerances to all sediment variables and it was not possible to separate the influence of
sediment nutrients from other sediment parameters or differences between rivers.
Comparisons of water sediment and plant tissue nutrient concentrations at sites
upstream and downstream of waste water treatment work outfalls on two rivers indicated
that the discharges affected both the water and sediment concentrations but not plant
tissue levels. The research suggests that the relationships between macrophytes and
sediments in lowland rivers are complex and confounded by the effect of the plants
themselves upon flow and sediment dynamics
Utilizing Colored Dissolved Organic Matter to Derive Dissolved Black Carbon Export by Arctic Rivers
No full textWildfires have produced black carbon (BC) since land plants emerged. Condensed aromatic compounds, a form of BC, have accumulated to become a major component of the soil carbon pool. Condensed aromatics leach from soils into rivers, where they are termed dissolved black carbon (DBC). The transport of DBC by rivers to the sea is a major term in the global carbon and BC cycles. To estimate Arctic river DBC export, 25 samples collected from the six largest Arctic rivers (Kolyma, Lena, Mackenzie, Ob’, Yenisey and Yukon) were analyzed for dissolved organic carbon (DOC), colored dissolved organic matter (CDOM), and DBC. A simple, linear regression between DOC and DBC indicated that DBC accounted for 8.9 ± 0.3% DOC exported by Arctic rivers. To improve upon this estimate, an optical proxy for DBC was developed based upon the linear correlation between DBC concentrations and CDOM light absorption coefficients at 254 nm (a254). Relatively easy to measure a254 values were determined for 410 Arctic river samples between 2004 and 2010. Each of these a254 values was converted to a DBC concentration based upon the linear correlation, providing an extended record of DBC concentration. The extended DBC record was coupled with daily discharge data from the six rivers to estimate riverine DBC loads using the LOADEST modeling program. The six rivers studied cover 53% of the pan-Arctic watershed and exported 1.5 ± 0.1 million tons of DBC per year. Scaling up to the full area of the pan-Arctic watershed, we estimate that Arctic rivers carry 2.8 ± 0.3 million tons of DBC from land to the Arctic Ocean each year. This equates to ~8% of Arctic river DOC export, slightly less than indicated by the simpler DBC vs DOC correlation-based estimate. Riverine discharge is predicted to increase in a warmer Arctic. DBC export was positively correlated with river runoff, suggesting that the export of soil BC to the Arctic Ocean is likely to increase as the Arctic warms
Short duration reservoir-release impacts on impounded upland rivers
No full textThe increasing number and scale of river impoundments throughout the 19th and 20th centuries means that the management of these impoundments is crucial to the future of global riverine biota. Impoundments such as reservoirs can affect rivers in a variety of ways, not least through the reduction in amplitude of the natural hydrograph, depriving rivers of ecologically important spate flows.
Many reservoir operators conduct regular safety tests, known as scour releases, during which large quantities of impounded water are released directly into rivers. This project assesses the impact of these releases on the hydrology and physio-chemistry of the receiving water bodies as well as upon fish movements and benthic macroinvertebrate abundance and diversity downstream of the reservoirs. The potential of such releases to mimic natural spate flows for ecological gain is also examined.
The work took place in the Yorkshire Water catchment area in northern England between 2007 and 2010. Passive Integrated Transponder (PIT) telemetry was used to assess the responses of brown trout Salmo trutta to these short-duration releases. Tagged fish were able to maintain position during the releases and showed no evidence of wash-out or upstream migratory movements associated with the releases.
Changes to macroinvertebrate abundance, diversity and community structure associated with the release were also examined. Some sites showed significant wash-out and community change following the releases while other sites were unchanged. Communities at impacted sites returned to pre-release structures within weeks of the releases.
Analysis of habitat use and characteristics suggest the responses of fish and macroinvertebrates to these reservoir releases were linked to habitat heterogeneity and the use of flow refugia. The negative impacts associated with the scour releases were minimal, while mimicked spate releases may improve salmonid spawning habitat and could re-introduce valuable flow variability to impounded catchments
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