Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/thsj19Determining suspended sediment loads from turbidity records / La détermination des charges en suspension des rapports sur la turbidité Abstract, The Pennsylvania Department of Transportation and the US Geological Survey are cooperating in several field studies to evaluate sediment control measures used during highway construction. Among the parameters being monitored are suspended sediment concentration and turbidity. Sediment loads are calculated from suspended sediment and water discharge data, but some sediment loads must be determined indirectly because it is virtually impossible to obtain sufficient suspended sediment samples to define all runoff conditions adequately. Sediment discharge-water discharge correlation curves have proved unreliable for streams affected by highway construction, so an alternative method using the turbidity record was developed during these studies.The field data reveal a good correlation between daily mean discharge-weighted turbidity and daily mean discharge-weighted suspended sediment concentration. Turbidity is monitored and recorded continuously, and the daily mean discharge-weighted turbidity is calculated from the turbidity and water discharge data. During periods when there are insufficient suspended sediment data, the daily mean discharge-weighted suspended sediment concentration is determined from the turbidity-sediment correlation and used with the daily mean water discharge to calculate a daily sediment load.This method of determining sediment loads from the turbidity record suggests a possiblity for computation of sediment loads by computer. Instrumentation now in use for recording water quality parameters on digital punch tape could be used to record the output from a turbidimeter. Then, for streams having a good correlation between suspended sediment concentration and turbidity, simultaneous water discharge and turbidity data could be used to determine sediment loads by computer. La détermination des charges en suspension des rapports sur la turbiditéRésumé, 'The Pennsylvania Department of Transportation' et 'the US Geological Survey' sont en coopération pour piusiers essais sur le terrain pour évaluer les mesures pour îe contrôle des sédi-ments pendant la construction des routes. Parmi les paramètres qu'on étudie de près se trouvent la concentration de matière en suspension et la turbidité. Les charges en suspension sont calculées des données disponibles de matière en suspension et d'écoulement d'eau. Cependant on doit déter-miner de façon indirecte quelques charges en suspension parce ce qu'il est à peu près impossible d'obtenir assez d'échantillons de matière en suspension pour pouvoir bien définir toutes les conditions d'écoulement. Les courbes de corrélation débit solide-débit d'eau se sont montrées peu fidèles pour des cours d'eau influencés par la construction des routes, donc on a développé une méthode alternative en utilisant le rapport ...
The trapping and thermal reemission of 100–300-eV Ar+ and Kr+ ions at a polycrystalline nickel target have been studied. For Ar+ and Kr+ the trapping probabilities are, respectively, 0.020 and 0.015 at 100 eV and 0.46 and 0.33 at 300 eV. A continuous temperature increase of the target releases trapped argon discontinuously by thermally activated processes at temperatures corresponding to activation energies of 1.12, 1.31, 1.48, 1.67, 1.83, and 2.13 eV. These energies are compared with activation energies which are determined by others for the removal of defects resulting from radiation damage or cold working of nickel. The lowest three energies are believed to be correlated, respectively, with interstitial migration, vacancy formation, and vacancy migration near the surface. The highest energy may be due to surface recrystallization from dislocations produced by the ion bombardment. The intermediate energies probably correspond to the motion of nickel surface atoms along the ridges of facets formed during the bombardment.
The West Branch Susquehanna River basin has a drainage area of 6,955 square miles in north-central Pennsylvania and comprises Hydrologic Accounting Unit 020502. A National Stream Quality Accounting Network (NASQAN) waterquality data collection site, maintained by the U.S. Geological Survey, is located on the river near its mouth at Lewisburg, Pennsylvania. Water-quality data are collected at numerous other sites throughout the basin by the Pennsylvania Department of Environmental Resources, Bureau of Water Quality Management. Data collected from the NASQAN site and the sites operated by the Pennsylvania Department of Environmental Resources from 1962 to 1982 were used to evaluate water-quality variability in the basin. The following objectives were addressed: (1) describe the surface-water quality upstream of the NASQAN site on an areal and temporal basis; (2) relate the water-quality variability, on both an areal and temporal basis, to general basin characteristics; and (3) assess the ability of the water-quality data collected at the NASQAN site to represent, on both an areal and temporal basis the water quality for Hydrologic Accounting Unit 020502 upstream from the site. Areally, the water quality varies considerably throughout the basin. Generally, the river was found to have moderately good water quality in the upper reaches, poor water quality in its middle reach, and good water quality near the mouth. Two tributaries, Moshannon Creek (median pH 3.9) and Bald Eagle Creek (median pH 7.8), had the most pronounced effect on the water quality of the river. Temporal trends were found in the concentrations of several of the constituents at most of the stations. Of the constituents analyzed, those which exhibited increasing or decreasing trends most frequently were pH, alkalinity, dissolved sulfate, total ammonia, and total nitrite plus nitrate. The largest trends were in the concentrations of total-recoverable aluminum, manganese, and zinc. Causes of areal variation were attributed to land use and geologic variations throughout the basin. Trends which indicated an improvement in water qualijty are believed to be caused by improvements in the treatment of acid mine drainage and wastewater. Trends which indicated degradation of water quality were generally found in areas where these types of treatment are not yet effective. The NASQAN site at Lewisburg was shown not to represent the water quality of the entire basin, either areally or temporally. It does, however, represent the water quality of the West Branch Susquehanna River at its mouth.
Inches (in) 25.4 Millimetres (mm) Acre .4047 Hectare (ha) Square miles (mi 2) 2.590 Square kilometres (km2) Cubic feet per second (ft^/s) .02832 Cubic metres per second (m3/s) OCCURRENCE OF PESTICIDE RESIDUES IN FOUR STREAMS DRAINING DIFFERENT LAND-USE AREAS
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