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  • Articles  (323)
  • Blackwell Publishing Ltd  (177)
  • Institute of Physics  (146)
  • American Association for the Advancement of Science (AAAS)
  • 1995-1999  (323)
  • Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics  (212)
  • Geography  (111)
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  • Articles  (323)
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  • 1
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : A significant portion of all pollutants entering surface waters (streams, lakes, estuaries, and wetlands) derives from non-point source (NPS) pollution and, in particular, agricultural activities. The first step in restoring a water resource is to focus on the primary water quality problem in the watershed. The most appropriate NPS control measures, which include best management practices (BMPs) and landscape features, such as wetlands and riparian areas, can then be selected and positioned to minimize or mitigate the identified pollutant(s). A computer-based decision sup. port and educational software system, WATERSHEDSS (WATER, Soil, and Hydro-Environmental Decision Support System), has been developed to aid managers in defining their water quality problems and selecting appropriate NPS control measures. The three primary objectives of WATERSHEDSS are (1) to transfer water quality and land treatment information to watershed managers in order to assist them with appropriate land management/land treatment decisions; (2) to assess NPS pollution in a watershed based on user-supplied information and decisions; and (3) to evaluate, through geographical information systems-assisted modeling, the water quality effects of alternative land treatment scenarios. WATERSHEDSS is available on the World Wide Web (Web) at .
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 1998-09-01
    Print ISSN: 0965-0393
    Electronic ISSN: 1361-651X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Institute of Physics
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 34 (1998), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : The decline of water quality in United States’ lotic ecosystems (streams and rivers) has been linked to nonpoint source nutrient loading (U.S. EPA, 1990). Determining limiting nutrients in streams is difficult due to the variable nature of lotic ecosystems. We developed a quantitative passive diffusion periphyton nutrient enrichment system, called the Matlock Periphytometer, to measure the response of attached algae (periphyton) to nutrient enrichment. The system is simple to build and provides quantitative nutrient enrichment of a surface for periphytic growth. The periphyton grow on a glass fiber filter, which allows complete recovery of periphyton for chlorophyll a analysis. A 14-kilodalton dialysis membrane was used as a biofilter to prevent bacterial and algal contamination of the nutrient solution. We determined the rates of diffusion of nitrogen and phosphorus ions across the Matlock Periphytometer's dialysis membrane and glass fiber filter over a 21-day period (42 and 22 μg/cm2/hr, respectively). We used the Matlock Periphytometer to determine the limiting nutrient in a woodland stream. Six replicates each of a control, nitrogen, and phosphorus treatment were placed in the stream for 14 days. The results indicated that phosphorus was the limiting nutrient in the stream for the period and location sampled.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 33 (1997), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : In order to assess the effects. of silvicultural and drainage practices on water quality it is necessary to understand their impacts on hydrology. The hydrology of a 340 ha artificially drained forested watershed in eastern North Carolina was studied for a five-year period (1988–92). Effects of soils, beds and changes in vegetation on water table depth, evapotranspiration (ET) and drainage outflows were analyzed. Total annual outflows from the watershed varied from 29 percent of the rainfall during the driest year (1990) when mostly mature trees were present to as much as 53 percent during a year of normal rainfall (1992) after about a third of the trees were harvested. Annual ET from the watershed, calculated as the difference between annual rainfall and outflow, varied from 76 percent of the calculated potential ET for a dry year to as much as 99 percent for a wet year. Average estimated ET was 58 percent of rainfall for the five-year period. Flow rates per unit area were consistently higher from a smaller harvested block (Block B - 82 ha) of the watershed than from the watershed as a whole. This is likely due to time lags, as drainage water flows through the ditch-canal network in the watershed, and to timber harvesting of the smaller gaged block.
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 33 (1997), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : A two-year study was conducted to assess the effect of hog manure on the losses of nitrogen and phosphorus in runoff and drainage from grain-corn (Zea mays L.) plots, and the importance of spring versus annual loads. Treatments consisted of mineral N-P-K fertilizer applied at rates of 152 kg N ha-1, 35 kg P ha-1, and 86 kg K ha-1; and hog (Sus scrofa domestica L.) manure applied preplant or post-emergence (six-to-eight leaf stage), at 152 kg N ha-1, 39 kg P ha-1, and 112 kg K ha-1. The plots were rototilled (7 cm depth) in spring to incorporate fertilizer and preplant hog manure, and fall chisel-plowed (15 cm depth) to incorporate chopped corn residues. They were arranged in a completely randomized plot design. Flow volumes and nutrient levels in runoff and drainage waters were monitored year round but occurred mainly during the snowmelt (March 25-April 9), and post.snowmelt (April 10-May 13) periods. Of the total amount of water lost during snowmelt, 90 percent was in runoff, while 92 percent occurred as drainage in the post-snowmelt period. Sixty-five percent of the total annual volume of water lost was lost during these two periods as runoff and drainage. Treatments did not affect the annual snowmelt or post-snowmelt N and P loads. Total annual loads averaged 8.0 kg TKN ha-1, 1.8 kg NH4-N ha-1, 43 kg NO3-N ha-1, 0.4 kg TP ha-1, and 0.15 kg PO4-P ha-1. Spring (snowmelt and ost-snowmelt) runoff and drainage loads averaged 2.9 kg TKN ha-1, 1.2 kg NH4-N ha-1, 18 kg NO3-N ha-1, 0.25 kg TP ha-1, and 0.04 kg PO4-P ha-1, which were 40 percent to 70 percent of the yearly nutrient loads. Therefore, the hog manure management systems examined were of no greater threat to the environment than mineral fertilizers. However, spring N and P losses do represent an important part of the annual nutrient loss budget, even with conservation practices.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 20 (1997), S. 0 
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract— In this investigation the Electron Channelling Contrast (ECC) technique in scanning electron microscopy (SEM) was applied to reveal the dislocation structures in the vicinity of surface fatigue cracks in comparison to those of cyclically-deformed recrystallized polycrystalline copper. The plastic zone around a fatigue crack was found to consist of an innermost region containing cells, followed by a region containing dense veins and PSBs, surrounded by a structure of loose veins, bundles and loop patches typical of the cyclically deformed matrix. A relation between plastic strain amplitude values deduced from cyclic stress-strain investigations and the dislocation structures near fatigue cracks are given. Typical regions of damage accumulation were identified and plastic strain contours for surface fatigue cracks established. The essentially non-destructive ECC technique is particularly suited to identify the changes in mesoscopic dislocation structures from surface layers to the interior of specimens over large specimen areas.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 32 (1996), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : A variety of management options are used to minimize losses of nitrogen (N), phosphorus (P), and other potential pollutants from agricultural source areas. There is little information available, however, to indicate the effectiveness of these options (sometimes referred to as Best Management Practices, or BMPs) on basin scales. The objective of this study was to assess the water quality effectiveness of BMPs implemented in the 3240 ha Lincoln Lake basin in Northwest Arkansas. Land use in the basin was primarily forest (34 percent) and pasture (56 percent), with much of the pasture being regularly treated with animal manures. The BMPs were oriented toward minimizing the impact of confined animal operations in the basin and included nutrient management, dead bird composter construction, and other practices. Stream flow samples (representing primarily base flow conditions) were collected bi-weekly from five sites within the basin from September 1991 through April 1994 and analyzed for nitrate N (NO3-N), ammonia N (NH3-N), total Kjeldahl N (TKN), ortho-P (PO4-P), total P (TP), chemical oxygen demand (COD), and total suspended solids (TSS). Mean concentrations of PO4-P, TP, and TSS were highest for subbasins with the highest proportions of pasture land use. Concentrations of NH3-N, TKN, and COD decreased significantly with time (35–75 percent/year) for all sub-basins, while concentrations of other parameters were generally stable. The declines in analysis parameter concentrations are attributed to the implementation of BMPs in the basin since (a) the results are consistent with what would be expected for the particular BMPs implemented and (b) no other known activities in the basin would have caused the declines in analysis parameter concentrations.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 35 (1999), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 33 (1997), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : Stream channel stability is affected by peak flows rather than average annual water yield. Timber harvesting and other land management activities that contribute to soil compaction, vegetation removal, or increased drainage density can increase peak discharges and decrease the recurrence interval of bankfull discharges. Increased peak discharges can cause more frequent movement of large streambed materials, leading to more rapid stream channel change or instability. This study proposes a relationship between increased discharge and channel stability, and presents a methodology that can be used to evaluate stream channel stability thresholds on a stream reach basis. Detailed surveys of the channel cross section, water surface slope, streambed particle size distribution, and field identification of bankfull stage are used to estimate existing bankfull flow conditions. These site specific stream channel characteristics are used in bed load movement formulae to predict critical flow conditions for entrainment of coarse bed material (D84 size fraction). The “relative bed stability” index, defined as the ratio of critical flow condition to the existing condition at bankfull discharge, can predict whether increased peak discharges will exceed stream channel thresholds.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1751-8369
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geography , Geosciences
    Notes: Marine geological investigations were performed across the Laptev Sea continental shelf and slope. Thirty sampling sites were selected covering a depth range of ca 3500 m. Maximum core recovery was 9 m. PARASOUND sub-bottom profiling was used for site surveying and provided important information on the depositional environment of the continental margin together with sedimentological and stratigraphical investigations.Undisturbed horizontal layering of the sea-floor sediments is a common feature for the Laptev Sea shelf. There is no indication for glaciation of the broad shelf region during the Last Glacial, since moraine deposits are missing. However, a high number of plough marks in places points to recent to sub-recent ice-erosion which has led to an intensive sediment reworking on the shelf. Several broadly incised river channels recorded near the shelf edge are related to Pleistocene drainage systems of large Siberian rivers which cut into the dry shelves during the Last Glacial Maximum and were subsequently filled during the Holocene. During the Last Glacial we therefore suspect a significant freshwater contribution from the Eurasian continent to the Arctic Oceans.The composition of the normally consolidated core sediments indicates a strong flux of terrigenous material, which is mainly provided by the Siberian rivers. Currents distributing the suspension load and sea ice are supposedly major agents transporting sediments across the shelf to the central arctic deep sea basin.Sediment cores from the upper and middle continental slope exhibit only minor lithological changes. Bioturbated, fine-grained sediments with high organic carbon contents dominate. The presence of free hydrogen sulphide gas within the sediment column indicates that an intense decay of organic matter under reducing conditions is taking place. Sedimentation rates are estimated to be ca. 50 cm/1000 years at the upper slope of the western Laptev Sea, being approximately 10 times higher than at the continental rise. The suboxic to anoxic environment diminishes at deep sea sites of the western Laptev Sea, where sedimentation rates and influx of organic matter are reduced.
    Type of Medium: Electronic Resource
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