Showing papers on "Turbidity published in 1972"

Effects of Sediment on Water Quality

Abstract: Flowing water in a stream carries sediment which is considered a pollutant because it interferes with many uses of water. Other pollutants in the water may be attached to or greatly affected by the sediment. The ultimate source of most sediment is soil loss from sheet erosion which can be computed by the universal soil loss equation. It may be as high as 100 metric tons/ha per year on a steep, loose, cropped soil, or on any soil left bare during construction activity. Nearly level land in Illinois may lose 10 tons/ha per year regularly. Sediment yield, or that delivered to a downstream point, can be estimated from the many measurements available. Yields are 15 tons/ha per year in Mississippi, the highest in the United States; yields are 10 in western Illinois and western Iowa, and less than 2 for the forest-covered east and the arid west. Sediment problems are usually proportionate to sediment yields. In the Upper Mississippi River Basin 27% of the land has sediment yield double the level described as being tolerable. In this basin total sediment damage of $25 million/year is about comparable in amount to the upstream damage done by all floods. Rivers carry a load of suspended sediment as a crucial part of their total energy balance. This natural sediment load is reflected in the median turbidity of 33 Jackson turbidity units found to be representative of all river waters in Illinois. If the suspended sediment load of a river is reduced, the stream will erode its bed or banks to pick up sediment to re-establish its energy balance. Traditional soil conservation measures will reduce soil loss from the farmer's field; this will also reduce sediment yield to a downstream reservoir. Reductions are often 70% to 90%. The river turbidity will be reduced, but it will never be eliminated. Stream turbidity affects many common uses of water. It is necessary to reduce this turbidity artificially in order to use the water.

Stabilized nonionic polysaccharide thickened water

Abstract: A reservoir oil displacing fluid that is relatively stable toward multivalent metal ions comprises an aqueous liquid solution of a viscosity enhancing amount of a water soluble nonionic polysaccharide and an effective amount of a water soluble metal salt adapted to clarify a calcium ion induced turbidity in that solution.

Turbidity of the atmosphere: source of its background variation with the season.

Abstract: laboratories. Scientists' motivations being what they are (including those at DBS), they cannot help but comproniuse situations where DBS scientists are asked to choose between two "alternatives," one developed by them and the other by outside scientists. We find just such a situation unfolding now, that is, monkey cell populations developed under contract to DBS, and quite naturally advocated by them, as compared to WI-38 developed by others and for which DBS even 10 years later still has "reservations" and "theoretical objections." It is by just such activities that the credibility gap between DBS and its constituency widens as they abrogate the very confidence on which their control authority rests. As Petricciani et al. quite rightly point out in respect to passaged monkey cells, "further evaluation by other independent investigators will be necessary to increase the level of confidence in the safety of these cells." It is to be hoped that these important studies will be done exhaustively and that the decade of WI-38 vaccine testing required by DBS to increase their level of oonfidence in WI-38 will be equally applicable to vaccines prepared in DBSFCL-1 and DBS-FRhL-2. LEONARD HAYFLICK Stanford University School of Medicine, Stanford, California

On the evaluation of atmospheric turbidity parameters from actinometric data

Abstract: Under average turbidity conditions, large variations in atmospheric turbidity parameters, namely the wavelength exponent α and turbidity coefficient β, were obtained when the usual Angstrom´s technique employing the graphical representation of intensity values in broad spectral bands was adopted With a view to improving the accuracy in the determination of turbidity parameter α, numerical integration of the actinometric data was performed using most recent values of the solar spectrum and the transmissivity of the classical Schott filters This paper shows that the amplitudes of turbidity parameter α thut the amplitudes of turbidity parameter α thus derived area real and yield more accurate values of turbidity in the atmosphere

Study of the influence of concentration on the time for first appearance of crystallization of polyethylene from xylene

Abstract: An experiment is reported in which a simple laser light-scattering technique is used to measure the time for a critical turbidity to appear during the crystallization of polyethylene in xylene. The effect is examined over the entire range of solution concentration, and it is found that the relation between this concentration and temperature is linear for all solutions, provided that the time for turbidity to develop is arranged to be the same in all cases. In the appendix it is reasoned that similar results could have been obtained if, instead, times had been measured to a given degree of crystallinity rather than of turbidity. Departures from this linearity at low concentrations are taken as indicating multimolecular nucleation for all concentrations greater than about 1%.

Estuarine turbidity, flushing, salinity, and circulation

Abstract: The effects of estuarine turbidity, flushing, salinity, and circulation on the ecology of the Chesapeake Bay are discussed. The sources of fresh water, the variations in salinity, and the circulation patterns created by temperature and salinity changes are analyzed. The application of remote sensors for long term observation of water temperatures is described. The sources of sediment and the biological effects resulting from increased sediments and siltation are identified.

Atmospheric Turbidity over Canada

Abstract: A method of evaluating the atmospheric turbidity coefficient from global solar radiation and diffuse sky radiation is formulated. By application of the present method, the turbidity coefficient is evaluated at urban (Montreal: 40°30′N, 73°37′W), suburban (Toronto: 43°48′N, 79°33′W), rural (Goose Bay: 53°18′N, 60°27′W) and arctic (Resolute: 74°43′N, 79°33′W) stations. Considering the arctic as the baseline station, its turbidity values are compared with the values of the other stations. Trends and seasonal variations of atmospheric turbidity are discussed using the data from 1966 to 1971. Turbidity values obtained from various concepts are compared.

Effect of a Grass and Soil Filter on Tucson Urban Runoff: A Preliminary Evaluation

Abstract: Storm runoff from the Tucson metropolitan area is unsuitable for most uses without processing. A lysimeter comprised of a grass and soil filter was constructed and is being evaluated as a water -quality treatment facility. The lysimeter is 200 feet long, 4 feet wide and 5 feet deep, and contains homogeneous calcareous loam covered by common grasses. Experimental apparatus was installed to divert less than a cubic foot per second of runoff from urbanized Arcadia Watershed. Runoff flows by gravity over the lysimeter, where surface inflow, surface outflow and subsurface outflow are measured and sampled. Four trials, each associated with a discrete runoff event, were conducted in the fall of 1971. Water samples were analyzed for inorganic chemical constituents, chemical oxygen demand (COD), coliforms, turbidity and sediment contents. Subsurface -outflow samples from initial trials were high in COD and total dissolved solids, representing soil flushing or leaching. Concentrations of inorganics reached a maximum value within a few hours of initial seepage, and then decreased. The peaking represents a salt build -up between trials. Concentrations of COD, coliforms, turbidity and sediment in subsurface -outflow samples decreased significantly during each trial. Surface -outflow samples had lower turbidity, COD, bacteria and sediment contents than surface -inflow samples. Turbidity, suspended and volatile solids, coliforms and COD in runoff samples may be reduced by grass and soil filtration. Increased grass development and soil settling work to produce a better quality effluent. Quantification of the lysimeter's effectiveness will be useful for urban watershed management. INTRODUCTION Water in the semiarid and arid environment is a limited resource which must be managed efficiently and economically. Urban water problems in such an environment are unique in that the watershed changes rapidly in time with urbanization. Hydrologic effects of urban growth include increase in runoff volume