Showing papers on "Water quality published in 1980"

Effectiveness of Vegetated Buffer Strips in Controlling Pollution from Feedlot Runoff

Abstract: A rainulator was used to test vegetative buffer strips for their ability to control pollution from feedlot runoff. Cropped buffer strips on a 4% slope reduced runoff and total solids transported from a feedlot by 67 and 79%, respectively. Total N and P were reduced by an average of 84 and 83%, respectively. Ammonium-N and PO<-P were similarly reduced, but average NOj-N in the runoff increased because some NOj-N was gained from the sorghum (Sorghum vulgare L.)sudangrass (Sorghum sudanense L.) and the oat (A vena saliva L.) buffer strips. During both years, the number of coliform organisms in the runoff water was reduced after runoff passed through the vegetated buffer strips. These results indicated that nonstructural feedlot discharge control practices are a promising alternative method for controlling pollution from feedlot runoff. Additional Index Words: runoff filter strips, vegetated filters, livestock waste, rainulator. Young, R. A., T. Huntrods, and W. Anderson. 1980. Effectiveness of vegetated buffer strips in controlling pollution from feedlot runoff. J. Environ. Qual. 9:483-487. 1 Contribution from the North Central Soil Conserv. Res. Lab., Sci. and Educ. Admin., Agric. Res., USDA, Morris, Minn., in cooperation with the Minn. Pollut. Control Agency and the Minn. Agric. Exp. Station, Sci. Journal Series 10,851. Received 9 Oct. 1979. 2 Agricultural Engineer, USDA, Morris, Minn. and Asst. Professor, Univ. of Minn., St. Paul, Minn.; Consulting Engineer, Tolz, King, Duvall, Anderson & Assoc., Inc., St. Paul, Minn.; and Head, Agric. Unit. Div. of Water Quality, Minn. Pollution Control Agency, Roseville, Minn., respectively. T. Huntrods was formerly Chief of Section of Agric. Waste, Minn. Pollution Control Agency, Roseville, Minn. The potential of runoff from livestock feedlots for polluting receiving bodies of water has been widely documented. Runoff from livestock feedlots has long been recognized as a potential source of pollution, and available technology has indicated that the best method of controlling runoff is to install a runoff catchment basin. As these basins were put into widespread use under existing state and federal feedlot pollution-control regulations, certain problems became apparent: (i) basins are expensive, even when available cost-sharing and tax incentives are taken into account; (ii) runoff control basins often require operators to purchase or rent liquid, manure-handling equipment; (iii) because no discharge-evaluation technique had been proven, enforcement and technical-assistance agencies often require catchment basins, even if the possibility of pollutant discharge is remote; and (iv) if the catchment basin is not maintained properly, odors at various times of the year may become a nuisance for both operators and their neighbors. Alternative pollution-control measures or landmanagement techniques that reduce or prevent discharge of pollutants were needed. This paper investigates the feasibility of using different management treatments to control the discharge of pollutants below active feedlots. Our specific objective was to evaluate the ability of land and cropping practices to absorb and retain pollutants in runoff from livestock feedlots. J. Environ. Qual., Vol. 9, no. 3,1980 483

Effects of a Windstorm and Forest Fire on Chemical Losses from Forested Watersheds and on the Quality of Receiving Streams

Abstract: A severe natural windstorm followed by a high intensity forest fire caused significant increases in runoff and in losses of nitrogen, phosphorus, and potassium from two small Precambrian watersheds. Both the windstorm and the fire had significant effects on water and chemical yields. Water yields in the two basins were 1.6 and 1.8 times the pre-impact means, respectively, in the year after the burn. Maximum chemical losses were observed for nitrate, with values of 3.4 and 9 times the pre-impact means for the two basins in the year after the burn. Increases in annual yields of most chemical parameters were 1.1 to 2.9 times the background. Both increased concentrations and increased flow volumes appear to be responsible for the increased nutrient losses.Key words: forest fire, windstorm, stream water quality, phosphorus, nitrogen, potassium losses, water yield

Mathematical Models Of Water Quality In Large Lakes Part 2: Lake Erie

Abstract: This research was undertaken to develop and apply a mathematical model of the water quality in large lakes, particularly Lake Huron and Saginaw Bay (Part 1) and Lake Erie (Part 2). A mathematical model was developed for analysis of the interactions between nutrient discharges to Lake Erie, the response of phytoplankton to these discharges, and the dissolved oxygen depletion that occurs as a consequence. Dissolved oxygen, phytoplankton chlorophyll for diatoms and nondiatoms, zooplankton biomass, nutrient concentrations in available and unavailable forms and inorganic carbon are considered in the model. Extensive water quality data for Lake Erie was analyzed and statistically reduced. Comparison of data from 1970 and 1973-74 to model calculations served for calibration of the model. 1975, a year when no anoxia was observed. A verification computation was also performed for Recent developments in phytoplankton growth and uptake kinetics are included in this analysis. The methods of sedimentary geochemistry are expanded to include an analysis of sediment oxygen demand within the framework of mass balances. Projected effects of varying degrees of phosphorus removal on dissolved oxygen, anoxic area, chlorophyll, transparency and phosphorus concentration are presented. This report was submitted in fulfillment of Grant No. R803030 by Manhattan College under the sponsorship of the U.S. Environmental Protection Agency. This report covers the project period March 26, 1974 to March 25, 1977 *

Environmental impact of nonpoint source pollution

Abstract: Modelling of non-point pollutants serves as a guide for understanding and quantifying the various soil, vegetation and climate elements responsible for controlling water quality. This book centers on watershed effects rather than total environment. It deals with pollutant transformations and environmental transport pathways into receiving waters. Agriculture, forestry, waste management by ground disposal, and water modelling are all discussed. (PSB)

Fish as a Factor Controlling Water Quality in Ponds

Abstract: Plankton of the fish pond Velký Palenec reveals a two-year periodicity, which is induced by the two year cycle of fishery management. During the two years of each cycle the biomass of carp increases considerably, while their numbers decrease. Whitefish are grown with the carp. In the first year of each cycle transparency and light penetration are high, chlorophyll and primary production of phytoplankton are low, large Daphnia are abundant and small zooplankton is scarce. In the second year of each cycle the reverse is true. Implications for regulation of water quality in shallow eutrophic bodies of water are discussed.

Rapid-infiltration research at Flushing Meadows Project, Arizona

Abstract: The Flushing Meadows Project in Arizona was initiated to investigate the feasibility of using wastewater for irrigation and the effects of infiltration on water quality. The results of the second phase of this 10 yr study, focusing on maximization of nitrogen removal and reduction of hydraulic loading, are discussed. Infiltration rates employed in this phase were 0.3-1 m/d, using a water depth of 0.3 m in the six experimental water basins. Removal of dissolved and suspended solids, nitrogen, phosphorus, organic carbon, and pathogens was monitored. Phosphate removal increased with increasing distance of wastewater movement; 65% of the total nitrogen content was removed. (3 graphs, 1 map, 23 references, 3 tables)

Soil Loss and Microbiological Quality of Runoff from Land Treated with Poultry Litter

Abstract: Because large amounts of poultry wastes are often applied to hilly land in the southeastern United States, information is needed on the environmental hazards of this practice. A rainfall simulator was used to study the effect of application of poultry litter (manure plus wood residues) on runoff water quality and soil loss, on moderately sloping (7%) land. Increasing rates of litter were surface-applied on fallow soil and grassland and also incorporated in the fallow soil. Runoff and soil loss were drastically decreased by litter application on fallow soil, and runoff was reduced on the grassed soil. The grassed soil had little soil loss with or without litter application. The coliform bacterial content of runoff water from plots receiving the higher application rates of surface-applied litter was appreciable afterward. Incorporating litter into soil generally reduced coliforms during the later stages of runoff. Moderate applications of poultry manure to sloping land (especially grassland) should not create a major water quality problem, unless excessive rainfall occurs. Additional Index Words: coliforms, pollution, erosion, washoff, manures, animal wastes. Giddens, J., and A. P. Barnett. 1980. Soil loss and microbiological quality of runoff from land treated with poultry litter. J. Environ. Qual. 9:518-520. The application of poultry manure to pasture and cropland, often at high rates, is a very common practice in the southeastern United States (8). This practice can re' Contribution from the Southern Piedmont Conserv. Res. Center, USDA, SEA, Watkinsville, Ga., and the Dep. of Agron., Univ. of Georgia, Athens, GA 30602. Received 26 Nov. 1979. 2 Professor of Agronomy, Univ. of Georgia, and Agricultural Engineer (retired), Southern Piedmont Conservation Research Center, USDA, SEA-ARS, respectively. suit in wash-off and, hence, stream pollution, especially at the higher application rates and on sloping land. Much of the manure plus wood residues (hereafter, called poultry litter) from the broiler houses is surfaceapplied to land near the poultry houses. Kunkle (3) reported that fecal coliform counts in runoff water from grazed pastures in Vermont were greatly influenced by rainfall and storm events. Fecal coliforms were better indicators of animal pollution than total coliforms in these studies. Malaney et al. (5) showed that the bacteriological water quality of Ohio farm ponds fed by runoff from agricultural land was good enough for watering animals and for domestic purposes with relatively minor purification. Smith and Douglas (10) found that fecal streptococci and microorganisms incubated at 20° C were higher in drainage water than in irrigation water from the Snake River in Idaho. Otherwise, bacteriological quality of the irrigation water was not significantly changed by using it for irrigation. Long et al. (4) found that incorporating 45 metric tons/ha of cattle manure into sandy soils near Auburn, Ala. for 3 years did not result in runoff biological oxygen demand (BOD) values exceeding those of untreated soil, nor did it increase nitrate (NO3-N) levels in runoff water. Meiman and Kunkle (6) reported that bacterial groups were a better indicator of the land-use impact on water quality than were suspended sediment or turbidity. They also found storms to be very important in increasing natural levels of sediment, turbidity, and organisms in streams of Colorado. The purpose of this study was to determine the possible pollution hazards from using poultry litter on sloping land and to show the effect of using poultry litter on soil erosion. 518 J. Environ. Qual., Vol. 9, no. 3,1980 MATERIALS AND METHODS The study was carried out at the Southern Piedmont Conservation Research Center, USDA, Watkinsville, Ga. in August 1966. The treatments consisted of surface applying 0, 5.6, 11.2, 22.4, 67.2, and 89.2 metric tons/ha of poultry litter to fallow soil surface and applying 11.2 and 22.4 metric tons/ha of poultry litter to fallow soil and incorporating it to a depth of about 10 cm, and surface applying 0, 5.6, 11.2, and 22.4 metric tons/ha of litter to coastal bermudagrass (Cynodon dactylon) sod. The soil was a Cecil sandy loam (clayey, kaolinitic, thermic Typic Hapludults) on a slope of 7%. Plots were 1.8 m wide by 10.7 m long. The poultry litter consisted of broiler chicken manure plus wood shavings that had accumulated in the broiler house for about 25 weeks. The litter contained about 25°70 moisture, 1.7% N, 0.8% P, and 1.3070 K (8). Water was applied uniformly to two plots simultaneously with a rainfall simulator (7) at the rate of 6.35 cm/hour for 120 rain. This was equivalent o a severe storm. Water and sediment were collected at lto 5-min intervals, after runoff began depending upon the runoff rate. The soil moisture content prior to simulated rainfall was less than field capacity. Total microbial counts were made by dilution plating, using soil extract agar (9) and total coliforms were counted the membrane filter technique using M-Endo medium (1), with four replications. Runoff and soil loss were determined by collecting aliquots of runoff water, measuring the volume, evaporating the water, and drying and weighing the sediment. All measurements were made in duplicate. Water used in the runoff study contained 1 coliform/ml. RESULTS AND DISCUSSION Runoff and Soil Loss Figure 1 shows the time for runoff to start after water application was begun. Runoff began in about 7 min from the fallow, no-liter plots. Increasing rates of poultry litter on the soil surface delayed runoff, with runoff for the 89.2 metric tons/ha treatment occurring after 53 min of simulated rainfall. This indicated that runoff would occur only during more intense storms when high litter rates were applied. Although the highest litter rates were not incorporated, incorporating the l 1.2 and 22.4 metric tons/ha rates decreased the time for runoff to start. Runoff from the 11.2 metric tons/ha litter-incorporated treatment started 7 min after water application started and for the same litter rate surface applied,

Concentration of coliphages from large volumes of water and wastewater.

Abstract: Membrane filter adsorption-elution technology has been extensively used for the concentration and detection of animal viruses from large volumes of water. This study describes the development of positively charged microporous filters (Zeta Plus) for the concentration of coliphages from large volumes of water and wastewater. Four different coliphages were studied: MS-2, phi X174, T2, and T4. Positively charged microporous filters were found to efficiently adsorb these coliphages from tap water, sewage, and lake water at neutral pH. Adsorbed viruses were eluted with a 1:1 mixture of 8% beef extract and 1 M sodium chloride at pH 9. Using this method, coliphages could be concentrated from 17-liter volumes of tap water with recoveries ranging from 34 to 100%. Coliphages occurring naturally in raw and secondarily treated sewage were recovered with average efficiencies of 56.5 and 55.0%, respectively. This method should be useful in isolation of rare phages, the ecology of phages in natural waters, and the evaluation of water quality.

Limnological survey of eight billabongs in the Magela Creek catchment, Northern Territory

Abstract: A 6-week survey of the physicochemical limnology of eight billabongs in the Magela Creek catchment of the Northern Territory was conducted between December 1977 and January 1978. This covered the important period corresponding to the end of the dry season and the commencement of the wet season. Each billabong was sampled approximately weekly. At the end of the dry season. the billabongs' waters had elevated conductivity and turbidity, and generally higher sodium, potassium. chloride, phosphate, nitrate and chlorophyll a concentrations. They were generally slightly acidic and. in some. the bottom water was anaerobic. With the commencement of the wet season. the billabongs were flushed and a significant improvement in water quality was noted. Temperature. dissolved oxygen and redox potential data were used to tentatively classify these billabongs as polymictic. Under certain circumstances mixing did not occur for several days. during which time the bottom waters became significantly depleted in dissolved oxygen. On the basis of limited nutrient and chlorophyll a data, the billabongs at the end of the dry season appear to be mesotrophic.

Use of saline water in energy development

Abstract: Maps were made of the Upper Colorado River Basin showing locations of coal deposits, oil and gas, oil shale, uranium, and tar sand, in relationship to cities and towns in the area. Superimposed on these are locations of wells showing four ranges of water quality; 1000 to 3000 mg/l, 3000 to 10,000 mg/l, 10,000 to 35,000 mg/l, and over 35,000 mg/l. Information was assembled relative to future energy-related projects in the upper basin, and estimates were made of their anticipated water needs. Using computer models, various options were tested for using saline water for coal-fired power plant cooling. Both cooling towers and brine evaporation ponds were included. Information is presented of several proven water treatment technologies, and comparisons are made of their cost effectiveness when placed in various combinations in the power plant makeup and blowdown water systems. A relative value scale was developed which compares graphically the relative values of waters of different salinities based on three different water treatment options and predetermined upper limits of cooling tower circulating salinities. Coal from several different mines was slurried in waters of different salinities. Samples were analyzed in the laboratory to determine which constituents had been leached from or absorbed bymore » the coal, and what possible deleterious effects this might have on the burning properties of the coal, or on the water for culinary use or irrigation.« less

Adsorption‐Desorption of Diuron by Freshwater Sediments

Abstract: Freshwater sediments were collected from eight different locations in California to study the influence of sediment properties on the adsorption and desorption of the model herbicide, diuron (3-(3,4-dichlorophenyl)-l,l-dimethylurea). The sediments were characterized to physical and chemical properties using the same methods used for soils. The sediments had a range of organic carbon of 0.91 to 19% and were high in silt and clay. The adsorption of diuron was described by the Freundlich equation. Adsorption at 25 °C expressed as the Freundlich coefficient, k, was positively correlated to the amount of organic carbon present. There was no correlation with total CEC. The desorption of diuron was evaluated by taking the difference between the slopes of the adsorption and desorption isotherms. As the difference between these slopes increased, less diuron was desorbed. These differences were positively correlated to k and organic carbon. Adsorption at temperatures of 5, 25, and 40°C on three sediments indicated that the adsorption of diuron decreased as the temperature increased. tern of a lake, then it would not only be important to study their chemical and physical properties, but also the potential retention or release of pesticides on these sediments. The capacity of lake sediments to adsorb or desorb pesticides is likely to be one of the most important factors which influence the concentration of a pesticide in the lake water. Since sediments are formed and exposed to conditions different from soils, it is important to know if the adsorption of a pesticide would vary with the same physical-chemical properties as for soils. The study was undertaken to determine the extent to which variation of several sediment characteristics, including organic matter, cation exchange capacity, and pH, affects sorption of the model herbicide, diuron (3(3,4-dichlorophenyl)-l,l-dimethylurea). Diuron is nonpolar herbicide of relatively low water solubility. It is used as both a preand postemergence herbicide. Additional Index Words: herbicides, pesticides, water quality, sediment characteristics, organic matter content, apparent heats of adsorption. Peck, D. E., D. L. Corwin, and W. J. Farmer. 1980. Adsorption-desorption of diuron by freshwater sediments. J. Environ. Qual. 9:101106. Although herbicide-soil interactions have been extensively studied, litte attention has been given to herbicide-sediment interactions. There have been some investigations of insecticide adsorption on lake sediment (Lotse et al., 1968; Vieth and Lee, 1971); however, there appears to be a lack of quantitative studies of the adsorption of herbicides on lake sediments. Poinke and Chesters (1973) have reviewed the literature on pesticide-sediment interactions. With the increasing use of herbicides in modern agriculture, it is likely that some will reach water bodies. Once in the water, it becomes important to understand the physical-chemical dynamics of the herbicide and sediment. It has been shown that sediments can play an important role in affecting the concentration of pesticides in a lake. Earlier investigations have shown (Bridges, 1961) that as the concentration of a given pesticide decreases in the water phase, there is a concomitant increase in the pesticide content of the sediment. As discussed by Chesters and Konrad (1971), these sediments may act as reservoirs, being able to recycle pesticides back into the aquatic environment. If lake sediments are considered as part of the life sys’ Contribution of the Dep. of Soil and Environ. Sci., Univ. of California, Riverside, CA 92521. The research leading to this report was supported by the Univ. of California, Water Resour. Center, as part of Water Resour. Center Project UCAL-WRC-W-485. Received 23 Sept. 1978. 2 Graduate Research Assistant, Graduate Research Assistant, and Associate Professor of Soil Science, Univ. of California, Riverside, respectively. Current address of senior author: Cooperative Extension Service, Univ. of Nevada, P.O. Box 651, Overton, NV 89040. Senior author is presently Soil and Water Scientist, Univ. of Nevada Agricultural Experiment Station, Logandale, NV 89021. MATERIALS AND METHODS The sediments were collected from eight different sites in California. Some of the chemical and physical properties of the sediments are listed in Table 1. The sediments were chosen to represent a number of differing environments and to be high in fine materials and organic matter. The sampling tool used to collect the sediment (Fig. 1) was modification of a tool designed by Barkley (1971). The sediment collection tube consisted of a 60-cm (2A-in) length of PVC pipe, 5 cm in) in diameter, with the circumference of one end beveled to aid penetration into the sediment. As the collection tube was pushed into the sediment, air and water were displaced upward through the tool stem. When the tube was filled with sediment, a rubber stopper was placed in the top of the tool. As the tool was withdrawn from the bottom, a vacuum was created holding the sediment in the tube. The success or failure of collecting a sediment sample depended upon the tool being completely air tight before removing the sediment from the bottom. Sediments were collected in water depths ranging from 0.5 to 4 m. Beyond a 4-m water depth it was difficult to maintain sufficient vacuum to hold the sediment in the tube. A composite sample consisting of 12 to 16 cores, 15 cm in depth, was collected at each site. The 0to 15-cm depth was obtained by sectioning the sediment core after removal from the collection tube. The sediment core slipped easily from the collection tube after releasing the vacuum. Intact 60-cm cores were retained in extra collection tubes for additional studies to be reported another time. Once collected, the sediments were immediately quickfrozen in dry ice. The frozen sediments were freeze-dried and each sampling site cornposited and ground to 60-mesh (0.25 mm). Preliminary investigations showed it necessary to reduce particle size to 60-mesh to provide a reproducible, homogeneous sample for the adsorption measurements. Preliminary screening through a 1-mm mesh removed fresh, undecomposed organic matter. Grinding may be expected to have an effect on the final particle size distribution in the sand fraction but would not be expected to significantly affect adsorption properties of the sediments. Most of the adsorption would be expected to be associated with the smaller size fractions. The chemical and physical properties of the sediments were determined using methods developed for soils. Organic carbon was determined using a programmed microcombustion apparatus in a pure oxygen atmosphere (Allison, 1965). In this method any sediments containing carbonates were treated with sulfurous acid before determining carbon. Total N was determined by the semimicro-Kjeldahl method (Bremner, 1965). The percent LOI (loss on ignition) was determined using a procedure developed for ash content (Sneddon et al., 1971) in which the sample was ignited 375°C for 16 hours. Cation exchange capacity of the sediment was determined using a modified BaCl2 method (Chapman and Pratt, 1961). J. Environ. Qual., Vol. 9, no. 1, 1980 101 Published January, 1980

Mathematical Models Of Water Quality In Large Lakes Part 1: Lake Huron And Saginaw Bay

Abstract: This research was undertaken to develop and apply a mathematical model of the water quality in large lakes, particularly Lake Huron and Saginaw Bay (Part 1) and Lake Erie (Part 2). A mathematical model of phytoplankton biomass was developed which incorporates both phytoplankton and zooplankton as well as phosphorus, nitrogen and silica nutrient forms. Extensive water quality data for Lake Huron and Saginaw Bay was analyzed and statistically reduced. brated by comparison of computed results to these data. The model was then caliAn exhaustive treatment of the kinetics employed for modeling the eutrophication process is presented. The sensitivity of the model to some of its key parameters is examined. In addition, responses of water quality in Lake Huron and Saginaw Bay system to variations in total phosphorus inputs are projected. This report was submitted in fulfillment of Grant No. R803030 by Manhattan College under the sponsorship of the U.S. Environmental Protection Agency. 1977. This report covers the project period March 26, 1974 to March 2.5,

Cost‐efficiency of transferable discharge permits for the control of BOD discharges

Abstract: The cost efficiencies of four systems of transferable discharge permits (TDP's) designed for BOD control were compared to least-cost and minimum uniform treatment strategies for achieving the same water quality. One of the four policies, viz., the policy in which the permits are defined in terms of the dissolved oxygen deficit contribution (DODC) at the checkpoint, always induces a least-cost treatment strategy. Another policy, for which the permits were defined in terms of the discharge rate (load) of ultimate BOD, is almost as efficient as the least-cost strategy for the example case of the Willamette River. The requirements for the high cost efficiency of the latter policy are identified, analyzed, and discussed. The economic cost for all four policies, some of which were very conservative, was found to lie between the least cost and the cost of minimum uniform treatment.

Quality of Tigris River passing through Baghdad for irrigation

Abstract: The effect of Baghdad city on the water quality of the Tigris River was studied from April 1977 to March 1978. The chemical and physical characteristics of the water which are necessary in judging the quality of water for irrigation were studied. It was found that Baghdad was responsible for increasing the water salinity from 390 to 443 mg l−1. Total hardness and turbidity were increased when the river passed through Baghdad. The increase in the total hardness was mostly due to the increase in Mg concentration. The results also suggested that there should be no problem from the heavy metals or inorganic N in this water when used for irrigation. The Tigris River water in Baghdad was classified as classC2S1; that is water of second class with regard to salinity and first class with regard to sodicity.

A Comparison of Nitrogen in Shallow Ground Water from Sewered and Unsewered Areas, Nassau County, New York, from 1952 through 1976a

Abstract: Median nitrogen concentrations of ground water and water from streams in Nassau County were statistically analyzed on an areal and temporal basis and by individual well to compare concentrations of nitrogen in ground water beneath sewered and unsewered areas. The comparison is discussed in terms of hydrogeologic conditions and major point and nonpoint sources of nitrogen. Although no significant differences in median nitrate concentrations during the 25-year period of record were observed between the sewered and unsewered areas, recent (1972–76) ammonium and nitrate data suggest a relative improvement in water quality in the sewered area. This finding is based on (1) significantly lower ammonium and nitrate concentrations in stream water of the sewered area during base flow, (2) significantly lower median ammonium concentrations in ground water in the sewered area, (3) significant decreasing long-term nitrate trends in water from 8 of 13 wells in the sewered area where records were sufficient for analysis, and (4) significantly lower median nitrate concentrations near the water table beneath the sewered area. The lack of significant difference between median nitrate concentrations in the sewered and unsewered areas may be in part due to sampling bias and to the considerable length of time necessary for ground water in the sewered area, which was contaminated by cesspool and septic-tank effluent before sewering, to reach a point of discharge in a stream or bay. In addition, ammonium leached from landfills and nitrate originating from nonpoint sources such as fertilizers and animal wastes, cannot be removed by sewers and may be obscuring water-quality improvements brought about by sewering.

Eutrophication in emilia-romagna coastal waters (north adriatic sea, italy): a case history

Abstract: Emilia-Romagna coastal area, which extends about 130 km from South of Po river mouth down to Cattolica town, is interested by severe eutrophication phenomena which can be considered the most relevant water quality problem in the whole Mediterranean. On the basis of horizontal distribution of nutrients it is possible subdivide the Emilia-Romagna area in four zones characterized by different water quality. In strictly coastal water occur Dinoflagellates bloom with densities reaching 68.4×106 cell/1. In outer coastal water Diatoms are the predominant species. Benthonic animals kill are due to anoxy. The primary limiting factor was identified as phosphorus. The area receives from different sources 19.000 metric tons of total phosphorus and 152.000 metric tons of total nitrogen. River Po contributes the largest part of these loads. The strategy to counteract eutrophication is based on the reduction of phosphorus inputs.