Foster I.D.L.,University of Northampton |
Foster I.D.L.,Rhodes University |
Collins A.L.,Soils |
Collins A.L.,University of Southampton |
And 4 more authors.
Journal of Paleolimnology | Year: 2011
Establishment of water quality criteria to guide catchment sediment management is required by the European Union (EU) Water Framework Directive. The topic, however, is hotly contested among scientists and policy makers. Existing legislation with regard to fine sediment was set by the EU Freshwater Fish Directive. Its guideline, i. e. mean annual suspended sediment concentration, is 25 mg l-1. Such a static target fails to capture the episodic nature of sediment transport. Furthermore, application of such global standards is inappropriate for a pollutant that is strongly controlled by spatial variation in key catchment drivers. Paleolimnology offers an approach for assessing background sediment pressures on watercourses, enabling determination of values for times pre-dating agricultural intensification. We propose that Modern Background Sediment Delivery to Rivers (MBSDR) across England and Wales can be determined using paleolimnology to quantify maximum feasible sediment reduction. No management programme should aim to reduce sediment loss to values below those resulting from background, natural physiographic and/or hydrological controls. Lacking generic tools to quantify process linkages between sediment pressures and biological impact, we propose that MBSDR could be taken to represent ecological demand for sediment inputs into watercourses required to support healthy aquatic habitats. In situations where generic tools exist for coupling sediment pressures and ecological impacts, assessment of MBSDR could be used to correct the gap between current or future projected sediment loss and biological condition. Existing paleolimnological data on sediment yields across England and Wales are presented to illustrate the approach and provide preliminary national estimates of MBSDR. We briefly consider the basis for reconstructing sediment yields using a paleolimnological approach and analyse temporal trends in published sediment yield, inferred for a range of landscape types. We also attempt to correlate sediment accumulation rates (SARs) with sediment yields to extend the MBSDR data base. Preliminary maps were generated to identify regions where further sediment yield data are needed to produce a more robust estimate of the spatial distribution of MBSDR across England and Wales. © 2011 Springer Science+Business Media B.V.
Sear D.A.,University of Southampton |
Jones J.I.,Queen Mary, University of London |
Collins A.L.,Rothamsted Research |
Hulin A.,Soils |
And 4 more authors.
Science of the Total Environment | Year: 2016
Fine sediments are known to be an important cause of increased mortality in benthic spawning fish. To date, most of the research has focussed on the relationship between embryo mortality and the quantity of fine sediment accumulated in the egg pocket. However, recent evidence suggests a) that the source of fine sediment might also be important, and b) that fitness of surviving embryos post-hatch might also be impacted by the accumulation of fine sediments. In this paper, we report an experiment designed to simulate the incubation environment of brown trout (Salmo trutta) and Atlantic salmon (Salmo salar). During the experiment, the incubating embryos were exposed to different quantities of fine (<. 63. μm) sediment derived from four different sources; agricultural topsoils, damaged road verges, eroding river channel banks and tertiary level treated sewage. Results showed that mass and source are independently important for determining the mortality and fitness of alevin. Differences between species were observed, such that brown trout are less sensitive to mass and source of accumulated sediment. We demonstrate for the first time that sediment source is an additional control on the impact of fine sediment, and that this is primarily controlled by the organic matter content and oxygen consumption of the catchment source material. © 2015.
Allin D.,University of Waterloo |
Stone M.,University of Waterloo |
Silins U.,University of Alberta |
Emelko M.B.,University of Waterloo |
IAHS-AISH Publication | Year: 2012
The impacts of large-scale land disturbance by wildfire on a wide range of water and related ecological services are increasingly being recognized worldwide. This study explores the long-term impact (6-7 years) of the 2003 Lost Creek wildfire on particulate phosphorus forms (NA1P, AP, OP) of suspended river sediment at a large regional scale (554 km2) in the Crowsnest River basin, Alberta, Canada. While total P concentrations were similar among burned and unburned river sediments, the mean bioavailable NAIP fraction remained approximately 70% greater and the organic P over 2-fold higher in sediments from five burned tributary watersheds compared to the reference site in the Crowsnest River study catchment. Because of the key role of phosphorus in regulating aquatic productivity in oligotrophic mountain rivers, these findings highlight the risk of a large scale and long-term legacy of wildfire in some mountain river systems. © IAHS Press 2012.
El-Shahway A.S.,Soils |
Mahmoud M.M.A.,Soils |
Udeigwe T.K.,Texas Tech University
Land Degradation and Development | Year: 2015
Changes in soil chemical properties resulting from continuous rice (Oryza sativa) cultivation on the Nile Delta soils of Egypt were examined. The eight soil profiles characterized for this study were designated as 0 (crop rotation without rice), 1 (crop rotation with rice after every 2years), and 2, 3, 4, 5, 6, and 7 representing continuous rice cultivation for 2, 4, 8, 12, 15, and 20years, respectively. Sampling was conducted at 0-20, 20-40, 40-60, and 60-80cm depths for each profile and samples analyzed for a suite of chemical properties. Soil pH, salinity indicators [electrical conductivity (EC), and exchangeable sodium percentage (ESP)], as well as soluble and exchangeable cations and anions such as chloride and sulfate, all tended to decrease with years of continuous rice cultivation, with a number of significant (p<0·05) differences observed. Cation exchange capacity (CEC) increased with years of continuous rice cultivation, with a 12% increase observed between 2- and 20-year continuous rice cultivation systems. Principal component analysis conducted on soil properties within the continuous rice cultivation systems (profiles 2-7) revealed two possible components, namely F1 (pH, EC, ESP, and soluble Na+, Mg2+, K+, Cl-, and SO4-2) and F2 (clay, organic matter, and CEC), which could be broadly associated to soil salinity and soil fertility, respectively. Findings suggested possible alterations in soil chemical properties by continuous rice cultivation practices on these Nile Delta soils of Egypt, Africa. © 2015 John Wiley & Sons, Ltd.