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A biomonitoring survey using the moss species Hypnum cupressiforme Hedw. was conducted in the surroundings of two steel plants located in the North of Spain. Levels of V, Cr, Ni, Cu, Zn, As, Cd, Hg, Pb and N were determined. Very high concentrations in the areas of study were detected when compared to nearby unaffected regions. Similar trends were observed for all the elements in the differently orientated transects, showing an appreciable influence of the NW prevailing winds of the region in the dispersion of pollutants, as well as a clear decreasing gradient in the concentrations of metals in mosses within a distance of 1500 meters from the facilities. A differentiation between the elements emitted by the chimney as result of the industrial activity (V, Cr, Ni, Cu and As) and those with a high presence in steel slag deposits (Zn, Cd, Hg and Pb) was observed. The range of contamination was also established by means of the Contamination Factor, indicating a category 4 out of 6 categories, which shows the high levels reported in the areas of study. A different dynamic was registered for nitrogen regarding the rest of the heavy metals analysed except for Hg, probably due to the elevated volatility and mobility of both elements, as well as their high persistence in the atmosphere. 相似文献
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Efforts to Reduce Mortality to Hydroelectric Turbine-Passed Fish: Locating and Quantifying Damaging Shear Stresses 总被引:1,自引:0,他引:1
Severe fluid forces are believed to be a source of injury and mortality to fish that pass through hydroelectric turbines.
A process is described by which laboratory bioassays, computational fluid dynamics models, and field studies can be integrated
to evaluate the significance of fluid shear stresses that occur in a turbine. Areas containing potentially lethal shear stresses
were identified near the stay vanes and wicket gates, runner, and in the draft tube of a large Kaplan turbine. However, under
typical operating conditions, computational models estimated that these dangerous areas comprise less than 2% of the flow
path through the modeled turbine. The predicted volumes of the damaging shear stress zones did not correlate well with observed
fish mortality at a field installation of this turbine, which ranged from less than 1% to nearly 12%. Possible reasons for
the poor correlation are discussed. Computational modeling is necessary to develop an understanding of the role of particular
fish injury mechanisms, to compare their effects with those of other sources of injury, and to minimize the trial and error
previously needed to mitigate those effects. The process we describe is being used to modify the design of hydroelectric
turbines to improve fish passage survival. 相似文献
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We review long-term changes that have occurred in factors affecting water quality in East Fork Poplar Creek (EFPC; in East
Tennessee) over a nearly 25-year monitoring period. Historically, the stream has received wastewaters and pollutants from
a major United States Department of Energy (DOE) facility on the headwaters of the stream. Early in the monitoring program,
EFPC was perturbed chemically, especially within its headwaters; evidence of this perturbation extended downstream for many
kilometers. The magnitude of this perturbation, and the concentrations of many biologically significant water-quality factors,
has lessened substantially through time. The changes in water-quality factors resulted from a large number of operational
changes and remedial actions implemented at the DOE facility. Chief among these were consolidation and elimination of many
effluents, elimination of an unlined settling/flow equalization basin, reduction in amount of blow-down from cooling tower
operations, dechlorination of effluents, and implementation of flow augmentation. Although many water-quality characteristics
in upper EFPC have become more similar to those of reference streams, conditions remain far from pristine. Nutrient enrichment
may be one of the more challenging problems remaining before further biological improvements occur. 相似文献
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Sand dunes are complex systems that contain several habitats, often as mosaics or transitions between types. Several of these habitats are afforded protection under European Legislation and in the UK nationally within Special Areas of Conservation (SAC) and Sites of Special Scientific Interest (SSSI). Natural England has a statutory duty to report to Europe on the conservation status and condition of sand dunes; and is required to report to the UK Government on designated sites. To achieve this we have sought ways of capturing, analysing and interpreting data on the extent and location of sand dune habitats. This requires an ability to be able to obtain data over large areas of coastline in an efficient way. Natural England and Environment Agency Geomatics have worked collaboratively for over 16 years, sharing data and ecological knowledge. In 2012 work started to evaluate the use of remote sensing to map UK BAP and Annex I sand dune habitats. A methodology has now been developed and tested to map sand dune habitats. The key objective was to provide an operational tool that will help to map these habitats and understand change on sites around England. This has been achieved through analysis of LIDAR and Compact Airborne Spectrographic Imager (CASI) data using Object Orientated Image Analysis. Quality Control (QC) and accuracy assessments have shown this approach to be successful and 11 sites have been mapped to date. These techniques are providing a new approach to monitoring change in coastal vegetation communities and informing management of protected sites. 相似文献
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In May 1985, a National Pollutant Discharge Elimination System permit was issued for the Department of Energy’s Y-12 National
Security Complex (Y-12 Complex) in Oak Ridge, Tennessee, USA, allowing discharge of effluents to East Fork Poplar Creek (EFPC).
The effluents ranged from large volumes of chlorinated once-through cooling water and cooling tower blow-down to smaller discharges
of treated and untreated process wastewaters, which contained a mixture of heavy metals, organics, and nutrients, especially
nitrates. As a condition of the permit, a Biological Monitoring and Abatement Program (BMAP) was developed to meet two major
objectives: demonstrate that the established effluent limitations were protecting the classified uses of EFPC, and document
the ecological effects resulting from implementing a Water Pollution Control Program at the Y-12 Complex. The second objective
is the primary focus of the other papers in this special series. This paper provides a history of pollution and the remedial
actions that were implemented; describes the geographic setting of the study area; and characterizes the physicochemical attributes
of the sampling sites, including changes in stream flow and temperature that occurred during implementation of the BMAP. Most
of the actions taken under the Water Pollution Control Program were completed between 1986 and 1998, with as many as four
years elapsing between some of the most significant actions. The Water Pollution Control Program included constructing nine
new wastewater treatment facilities and implementation of several other pollution-reducing measures, such as a best management
practices plan; area-source pollution control management; and various spill-prevention projects. Many of the major actions
had readily discernable effects on the chemical and physical conditions of EFPC. As controls on effluents entering the stream
were implemented, pollutant concentrations generally declined and, at least initially, the volume of water discharged from
the Y-12 Complex declined. This reduction in discharge was of ecological concern and led to implementation of a flow management
program for EFPC. Implementing flow management, in turn, led to substantial changes in chemical and physical conditions of
the stream: stream discharge nearly doubled and stream temperatures decreased, becoming more similar to those in reference
streams. While water quality clearly improved, meeting water quality standards alone does not guarantee protection of a waterbody’s
biological integrity. Results from studies on the ecological changes stemming from pollution-reduction actions, such as those
presented in this series, also are needed to understand how best to restore or protect biological integrity and enhance ecological
recovery in stream ecosystems. With a better knowledge of the ecological consequences of their decisions, environmental managers
can better evaluate alternative actions and more accurately predict their effects. 相似文献
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