The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Simon M. Hutchinson - One of the best experts on this subject based on the ideXlab platform.
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Chernobyl radiocaesium in Upland watershed-lake systems, Galloway, south west Scotland
Journal of Paleolimnology, 1994Co-Authors: Simon M. HutchinsonAbstract:Levels of Chernobyl radiocaesium found in the Upland Region of Galloway, south west Scotland were relatively high e.g. catchment mean^134Cs inventories ranged from 5.72±2.64 kBq m^2 to 8.72±1.46 kBq m^2. The nuclear weapons test^137Cs content of soils and peats was significantly augmented. Accurate assessment of spatial variations and temporal changes in the levels of contamination, however, are inhibited by its marked, short-range heterogeneity. No significant change in mean catchment inventories was detected over a twelve month period. Lake sediment inventories, however, were consistently enhanced from initially lower levels of contamination than their catchments' surfaces. Pre Chernobyl catchment and lake sediment^137Cs inventories, however, show no such contrast. Both are substantially lower than rainfall based predictions. These observations of the relative levels of Chernobyl and pre-existing radiocaesium in watersheds and their waterbodies have important implications for both the assessment of the catchment and lake residence times of particle-associated contaminants and the use of lake sediment records as monitors of such pollutants.
Murray H Miller - One of the best experts on this subject based on the ideXlab platform.
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Tillage translocation and tillage erosion in the complex Upland landscapes of southwestern Ontario, Canada
Soil & Tillage Research, 1999Co-Authors: David A. Lobb, R. Gary Kachanoski, Murray H MillerAbstract:Tillage translocation and tillage erosion were measured throughout the topographically complex landscapes of two fields in the Upland Region of southwestern Ontario. Translocation of soil by tillage was measured by labelling plots of soil with chloride and measuring the tracer's forward displacement in response to single passes by four tillage implements (mouldboard plough, chisel plough, tandem disc and field cultivator). The change in translocation within the landscape was used to measure tillage erosion. All four implements were erosive. A relationship between tillage translocation and slope gradient was observed; however, the variability in translocation could not be explained by slope gradient alone. Slope curvature was responsible for some translocation through the planning action of tillage implements. Tillage depth and speed were subject to considerable discontinuous and inconsistent manipulation by the operator in response to changing topographic and soil conditions. Tillage speed decreased by as much as 60% during upslope tillage and increased by as much as 30% during downslope tillage, relative to that on level ground. Tillage depth decreased by as much as 20% and increased by as much as 30%, relative to that on level ground. This manipulation is typical for tillage in complex landscapes and was presumed largely responsible for the variability in the results. The manipulation of tillage depth and speed are affected by the tractor-implement match and the responsiveness of the tillage operator.
L Bonomo - One of the best experts on this subject based on the ideXlab platform.
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Combined use of the EPA-QUAL2E simulation model and factor analysis to assess the source apportionment of point and non point loads of nutrients to surface waters.
The Science of the total environment, 2006Co-Authors: A Azzellino, R Salvetti, R Vismara, L BonomoAbstract:Diffuse pollution is generally indirectly estimated by area and specific emission factors as function of land use. However in many cases these estimates were proven to be remarkably inaccurate. Aim of this study was to combine a water quality simulation model, (USEPA-QUAL2E) and Factor Analysis to increase the understanding of the water pollutants source apportionment. The study concerned two different watersheds, an Upland area characterised by a very scarce agricultural use, and another area covering both the Upland and the lowland physiographic Regions. Particularly the lowland Region is included in one of the most productive agricultural areas in Italy. By comparing instream measurements with QUAL2E simulations during dry and wet weather conditions, a good fit (errors +/-20%) was found for the dry weather scenario, whereas very poor was the model performance on the wet weather scenario. This was in the same way expected since the rainfall-driven pollutants scenario deviates significantly from QUAL2E general assumptions of constant emissions in steady state streamflow conditions. However the poor fit was also due to the scarcer reliability of the adopted non point emission estimates. Despite of approximations the model wet weather simulations enabled to estimate the non point contribution to the instream load at the rainfall event scale resolution. Such diffuse sources contribution was found around 80% in the area of extensive agricultural land use, and around 40% in the Upland Region. Factor Analysis applied to the instream measurements data shed light on the exchange from the groundwater to the surface water system that occurred in the Upland Region. The hypothesis of a groundwater contribution to the instream total load of nitrates was also supported by QUAL2E simulations that, when considering only the point loads, systematically underestimate the dry weather nitrate concentrations. The same pattern was not observed for the lowland Region.
Robert C. Ferrier - One of the best experts on this subject based on the ideXlab platform.
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Natural flow in managed catchments: A case study of a modelling approach
Water Research, 1999Co-Authors: S. M. Dunn, Robert C. FerrierAbstract:In the U.K., the water resources of many catchments are heavily managed and the existing constraints on their use must be built into future management. Recent developments in catchment modelling mean that the practical use of models, to analyse catchment behaviour and assist with the management process, is a feasible option. However, few models include appropriate water management components that will permit application to those areas for which they are most needed. This paper describes the integration of simple management controls into a spatially distributed hydrological model and illustrates how the model can be used to assist in catchment management, through a case study of the Carron catchment in Central Scotland. The model was successfully applied to predict flow in both the Upland Region of the catchment, where there are several reservoirs and significant transfers of water and the lowland Region of the catchment, which is a predominantly urban area. A simple modification to the water management procedures illustrates how the model may be used to help achieve naturalisation of the flow regime, thus satisfying the requirements of the precautionary principle.
Richard W. Battarbee - One of the best experts on this subject based on the ideXlab platform.
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Persistent surface water acidification in an organic soil-dominated Upland Region subject to high atmospheric deposition: The North York Moors, UK
Ecological Indicators, 2014Co-Authors: Chris D. Evans, Tom Chadwick, David Norris, Edwin C. Rowe, Tim H.e. Heaton, Philip Brown, Richard W. BattarbeeAbstract:Abstract The North York Moors National Park, in Northeast England, is one of the few Upland areas of the United Kingdom located immediately downwind of major sulphur and nitrogen emission sources. Despite this, few studies of air pollution impacts have been undertaken, and there is no formal long-term Upland water quality monitoring site. We examined the condition of surface waters in the National Park based on (1) a unique 20 year stream pH record from three locations; and (2) a snapshot survey of 51 surface waters draining moorland and conifer plantations. Interpretation was supported by sulphur isotope analysis of a subset of water samples, and a diatom survey of one of the monitoring streams. Long-term pH data for a stream draining the peat plateau demonstrate extreme, year-round acidification, with recovery only evident in the last few years. Lower-elevation sites are less acidic, but show similar temporal trends, and are characterised by frequent and severe acid episodes. The snapshot survey confirmed that acidification of the moorland area is widespread, to a degree observed in few other areas globally; out of 37 moorland streams sampled, 32 had an acid neutralising capacity (ANC) below −50 μequiv. l−1. Sulphate was found to be (by far) the dominant cause of acidification, and sulphur isotope analysis confirmed that this derives primarily from atmospheric deposition. Nitrate concentrations remain low, indicating that the organic moorland soils continue to retain most incoming nitrogen. It appears that conifer planting has exacerbated acidification, leading to fivefold higher nitrate and threefold higher aluminium concentrations compared to the moorland sites. Available biological data suggest that waters in the Region have been impoverished by acidification. We speculate that the slow recovery of surface waters in the North York Moors is due to the release of a legacy of stored sulphur from the peats, released during droughts. We conclude that: (1) acidification is far from being a solved problem in this sensitive near-source Upland Region, despite reductions in sulphur deposition; (2) plantation forestry has exacerbated the effects of atmospheric pollution, and triggered nitrogen saturation; (3) the lack of any formal long-term monitoring in the North York Moors represents a major gap in the current evidence base for the effects of long-range air pollutants on UK Upland ecosystems.
