Showing papers on "Water quality published in 1978"

The Pesticide Content of Surface Water Draining from Agricultural Fields—A Review

Abstract: The literature on pesticide losses in runoff waters from agricultural fields is reviewed. For the majority of commercial pesticides, total losses are 0.5%0 or less of the amounts applied, unless severe rainfall conditions occur within 1–2 weeks after application. Exceptions are the organochlorine insecticides, which may lose about 1% regardless of weather pattern because of their long persistence; and soil surface-applied, wettable-powder formulations of herbicides, which may lose up to 5%, depending on weather and slope, because of the ease of washoff of the powder.Pesticides with solubilities of 10 ppm or higher are lost mainly in the water phase of runoff, and erosion control practices will have little effect on such losses. Organochlorine pesticides, paraquat, and arsenical pesticides, however, are important cases of pesticides which are strongly adsorbed by sediments, and erosion control can be important in controlling losses of these compounds.The behavior and fate of pesticides in streams receiving runoff is generally not known. Information on such factors as time and distance of impact of a given runoff event, ability of local ecosystems to recover from transient pesticide concentrations, and dissipation or concentration processes in aquatic ecosystems will have to be obtained before “edge-of-field” pesticide losses can be related to water quality in receiving waters.

Effects of Clay Type and Content, Exchangeable Sodium Percentage, and Electrolyte Concentration on Clay Dispersion and Soil Hydraulic Conductivity

Abstract: The hydraulic conductivities and gradients along soil columns packed with montmorillonitic, vermiculitic, and kaolinitic soils adjusted to different levels of exchangeable sodium were determined at different salt concentrations. The data show that plugging of pores by dispersed clay particles is a major cause of reduced soil hydraulic conductivity for surface soils irrigated with sodic waters. Additional Index Words: hydraulic conductivity, clay dispersion, sodic soils, exchangeable sodium, water quality. View complete article To view this complete article, insert Disc 4 then click button8

Water resources and the land-water interface.

Abstract: Development and implementation of local and regional plans to control nonpoint sources of pollution from agricultural land are major mandates of section 208 of Public Law 92-500. Many planners tend to equate erosion control as measured by the universal soil loss equation with improvements in water quality. Others implement channel management practices which degrade rather than improve water quality and thereby decrease the effectiveness of other efforts to control nonpoint sources. Planners rarely recognize the importance of the land-water interface in regulating water quality in agricultural watersheds. More effective planning can result from the development of "best management systems" which incorporate theory from all relevant disciplines.

Numerical estimates of coliform mortality rates under various conditions

Abstract: Coliform bacteria are discharged in waste water treatment plant effluents and are con tained in runoff from urban areas and non point sources. Concentration levels of these bacteria are regulated by water quality stan dards, particularly for evaluation and protec tion of bathing, shell-fishing, water supply and other health-related, water use activities. As progress is made, on a national scale, toward the goals of upgrading and maintaining water quality, analysis of the distribution of coli forms in bodies of water should be a part of planning efforts. This paper provides numerical estimates of coliform mortality rates in fresh water and sea water systems, and as a function of light and temperature levels. Data from the literature are presented to illustrate the range of mor tality rates observed in laboratory studies and natural bodies of water. The intent of this paper is to provide numerical estimates of coli form mortality rates in the context of the wide variations in experimentally generated data.

Use of Hydroponics to Maintain Quality of Recirculated Water in a Fish Culture System

Abstract: Fish production, biofiltration, and hydroponics were linked in a closed system of recirculating water. Fish tanks were stocked with channel catfish (Ictalurus punctatus) and the fish were fed daily. A revolving plate-type biofilter was used. Three field varieties of tomatoes (Lycopericon esculentum) were planted in outdoor hydroponic tanks. Three production units were operated during the 1976 growing season. All significant water quality variables were monitored. Performance was evaluated in terms of water quality, vegetative and fruit production of the tomatoes, and growth of the fish. Fish survival was high, but growth was below maximum because the temperature in the system was below optimum. The average loading rate of fish for the three units at harvest was 31.5 kg/unit, 489 g/tomato plant, 1.9 kg/m2 of hydroponic area, and 691 g/m2 of biofilter surface. Excellent water quality was maintained. The biofilter satisfactorily converted the waste to nitrate-N and phosphate-P and the hydroponic sys...

Toxicity of a Mixture of Metals on Freshwater Algae

Abstract: Recommended levels of a number of metals for Great Lakes Water Quality Objectives were found to be very toxic to freshwater algae when these metals were present simultaneously in lake water and cul...

Seasonal Runoff Losses of Nitrogen and Phosphorus from Missouri Valley Loess Watersheds

Abstract: N/ha) was 39.64 and 3.04 ka/ha, resuectively. About Seasonal losses of nitrogen and phosphorus in surface runoff were determined for a 7-year period from three con-cropped watersheds in southwestern Iowa. Three seasonal periods were defined: fertilizer, seedbed, and establhment period from April through June (PI); reproduction and maturation period from July through November (PZ); and residue period from December through March (P3). Most of the average annual total N and P losses were associated with the sediment portion of runoff and occurred during Pl. The extreme susceptibility of the loess s o b to erosion during P1 must be taken into account when designing consenation practices to control plant nutrient losses. Seasonal discharges of runoff, sediment, and nutrients were much lower from a level-terraced watershed than from two contour-farmed watersheds, which demonstrates the benefit of terracing in resource coasenation. Average annual soluble N and P losses were quite low and never exceeded 1% of the annual fertilizer application. These losses were the highest during P3 from the contour-farmed watersheds. Water and sediment weighted nutrient concentrations were the highest from the contour-farmed watersheds during P3, when residues covered the soil surface. Leaching of soluble nutrients from the residue and the greater selectivity of the soil erosion process for the finer fractions of the soil (i.e., clay and organic material) during snowmelt runoff are probably the factors responsible. Additional I n d u Words: water quality, nutrient loss, surface run-

Pollution indicators and other microorganisms in river sediment.

Abstract: Bacterial indicators of the potential presence of human pathogens in aquatic systems have traditionally been enumerated from the water column. However, recent literature has in cluded several reports of increased numbers of both indicators and pathogens in sediments. Downstream of a wastewater effluent, Hen dricks;1 found approximately 90 percent of Salmonella isolates in the sediments, and dem onstrated a higher recovery rate from sediments than from water. Van Donsel and Geldreich 2 recovered 100 to 1 000 times more fecal coli forms in river mud than in the overlying water. Grimes 3 showed increased numbers of fecal coliforms in the Mississippi River during and after channel dredging and concluded that the resuspended sediments had released coliforms into the water. Reports of survival and multiplication of indicators and pathogens in sediments are even more significant in terms of basic pollution indicator theory. Enteric organisms have been shown to metabolize freshwater sediment eluates,4 and grow and reproduce in predator free marine sediment systems.5 Thus, rapid die-off from the water column may result in increased sediment populations from settlement. The importance of benthic microorganisms is recognized in shallow water systems, since the benthic community accounts for most of the system's biomass 6_8 and metabolic activ ity.6? 7' 9?10 It is clear that sediment analysis for indicators can provide additional water quality information. In the light of this recent evidence, data collected during a 3-year study of indicator and other bacteria and yeasts in the Shetucket River basin in northeastern Connecticut will be presented. For all microorganisms considered, higher concentrations were noted in sediments than in subsurface waters, and a sufficient sup

Toxicity of Cadmium to Goldfish, Carassius auratus, in Hard and Soft Water

Abstract: Variations in cadmium form and concentration and in selected water quality parameters (pH, dissolved oxygen, total hardness, total alkalinity, conductivity) were monitored during static bioassays c...

Diversity as a measure of benthic macroinvertebrate community response to water pollution

Abstract: The assumption that water pollution causes a depression in the diversity of benthic macroinvertebrates as measured by the Shannon index and similar diversity indices is questioned. An interpretation of the community response of benthic macroinvertebrates to pollution in the Millers River, Massachusetts is developed from species presence-absence and abundance data in conjunction with published information on the species' environmental tolerances as compared to chemical water quality data. This interpretation is compared with one derived solely from diversity index values. The interpretations are quite different; the differences may be attributed to other environmental factors such as impoundments and flow reductions which influence the fauna and thus the diversity index value, but which are not related to pollution. In addition, several intrinsic features of the diversity indices increase their bias.

Water-quality indices for specific water uses

Abstract: ____________________________

The Effects of Vegetation Removal by Grass Carp on Water Chemistry and Phytoplankton in Indiana Ponds

Abstract: Water quality parameters and phytoplankton in ponds stocked with grass carp, Ctenopharyngodon idella (test ponds) and in control ponds were compared during the summers of 1975 and 1976. Grass carp rapidly consumed available aquatic vascular plants. Dissolved oxygen levels in test ponds remained high as long as bottom growths of the filamentous green alga, Spirogyra sp. were present, but consumption of this alga in addition to vascular vegetation led to significantly lower dissolved oxygen concentrations in the water directly above the sediments. The most consistently affected parameters were turbidity and potassium concentrations, both of which were significantly higher in test ponds. Phytoplankton populations consisting primarily of dinoflagellates were not affected by grass carp introduction. As much as 54% of the phosphorus and 42% of the nitrogen released by consumption of plants were incorporated into new fish tissue. Most of the phosphorus not taken up by the fish was sequestered into compo...

Use of Ozone and Chlorine in Water Utilities in the Federal Republic of Germany

Abstract: Experiences in German water utilities cannot be discussed without mentioning a fundamental approach that decisively influenced the improvement of drinking water quality in that country. This philosophy, summarized in the following paragraphs, is the reason that the formation of haloforms during chlorination occurred on a considerably smaller scale in the Federal Republic of Germany than, for example, in the US. 1. The historical improvement of drinking water. A groundwater source fact that groundwater was, and today still is, the most important source of drinking water. A ground water source that produced chemically and bacteriologically unobjectionable water because of the surrounding area of the wells and the soil conditions was always preferred to one that required treatment and chlorination. Nowadays hundreds of water utilities provide water without chlorination and have no problems with bacteria in the distribution system. Among them are large cities like Karlsruhe and Munich.

Nitrous oxide in fresh water systems - An estimate for the yield of atmospheric N2O associated with disposal of human waste

Abstract: The N2O content of waters in the Potomac and Merrimack Rivers was measured on a number of occasions over the period April to July 1977. The concentrations of dissolved N2O exceeded those which would apply in equilibrium with air by factors ranging from about 46 in the Potomac to 1.2 in the Merrimack. Highest concentrations of dissolved N2O were associated with sewage discharges from the vicinity of Washington, D. C., and analysis indicates a relatively high yield, 1.3 to 11%, for prompt conversion of waste nitrogen to N2O. Measurements of dissolved N2O in fresh water ponds near Boston demonstrated that aquatic systems provide both strong sources and sinks for atmospheric N2O.

Water Treatments in Trickle Irrigation System

Abstract: Water treatment requirements of Colorado River water for eight types of trickle emitters were being determined using six kinds of treatments, including screen and sand filtration, and combinations of hypochlorite and acid additions. With the water used, removal of suspended particulate materials by sand filtration maintained emitter performance over the 2-yr study, but sediment buildup had to be controlled for long-term maintenance by flushing the lines and treating with chemicals.