ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1976.tb03128.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1976.tb03129.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTIn truly arid regions there is essentially no direct penetration of rainfall. Recharge to ground water is not only infrequent, but extremely localized, occurring only where surface runoff has been channelized or ponded. Over those vast desert areas covered by sparse xerophytic vegetation, the scant rainfall has little or no chance of becoming ground‐water recharge. Such water is quickly dissipated by capillarity‐assisted evaporation, or through rapid evapotranspiration by short‐lived annuals. Where perennial xerophytes cover the ground surface, the extensive shallow root systems quickly utilize all of the rainfall stored in the soil. Beneath the infrequently moistened soil zone is the lower part of the vadose zone, extending to water tables which are usually at depths of tens to hundreds of feet. Almost always these vadose zones have moisture contents well below field capacity.Regardless of the cause, these dry vadose zones are capable of holding additional water, at least up to field capacity. And no water‐carried pollutants can reach the water table from the ground surface until a pre‐wetted path has been formed for the entire vertical distance. A practical use of this water‐holding capacity can be made in the design of wastewater tailings ponds, with predictable safety and with great economic benefit. However, only in predictable geologic conditions, and in limited amounts can the use of this water‐holding capacity be recommended. On the other hand, to make no use whatsoever of these great natural dry sponges would be an e

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1976.tb03130.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTBecause of increasingly stringent laws governing discharge of fluid wastes to surface waters, the alternative of discharge to the subsurface has become attractive. The physical‐chemical processes that prevail in the subsurface are not well understood, but they are clearly not identical to processes of purification in surface waters. For example, in the subsurface the process of oxidation may be of little value in significantly reducing the concentration of discharged contaminants; in contrast, oxidation plays an important role in purifying surface waters. Eleven physical‐chemical processes can be identified as having potential value for purifying wastes discharged to the subsurface, as follow: dilution, buffering of pH, precipitation by reaction, hydrolysis, oxidation or reduction, filtration, volatilization, biological assimilation, radioactive decay, membrane filtration, and sorption.Discharge to the vadose zone may be a safe means of disposal of wastes in arid regions. But it is necessary to carefully test the suitability of a particular site for a particular waste. Processes of purification in the vadose zone can be incorporated into a workable plan of discharge if adequate studies and safeguards are employed. Regulations governing subsurface discharge should take into account the physical‐chemical processes that may act to purify the waste fluids. In one set of experiments, a soil from Sulfur Springs, New Mexico was capable of removing large quantities of dissolved molybdenum and copper from a synthetic mill water, and the soil was able to quantitatively retain the copper during subsequent leaching by fresh and metal‐free mill waters. Such studies permit rational plans of discharge to be de

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1976.tb03131.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTSoils and aquifers can function as effective and economical filter systems for advanced treatment of conventionally treated sewage and other wastewater. The wastewater is applied to the land with low‐rate or high‐rate infiltration systems. Physical, chemical, and biological processes in the soil improve the quality of the wastewater as it percolates through the vadose zone and into the aquifer to become renovated water. The quality of the renovated water, however, often is not as good as that of the native ground water. To utilize the land for treatment of wastewater, without trading a problem of surface‐water pollution for one of ground‐water contamination, the spread of renovated water in the aquifer must be restricted. This can be accomplished by locating the system so that the renovated water drains naturally into a stream or other surface water, or by artificially removing renovated water from the aquifer with wells or drains at some distance from the application area. Examples are given of various systems that utilize these principles, and general design criteria are presented. Proper design involves analysis of underground‐flow systems for various system geometries. Methods for measuring hydraulic conductivity, particularly in the vadose zone, are briefly

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1976.tb03132.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTIndividual subsurface liquid waste disposal has been cited as a source of ground‐water contamination. Wastewater treatment systems using emergent marsh vegetation planted in a gravel substrate in a plastic‐lined trench could be used to treat septic tank effluent. A pilot plant treating unchlorinated primary municipal effluent achieved the following reductions in mass: BOD5‐77%; COD‐71%; orthophosphate–35%; total phosphorus–37%; nitrate–22%; coliform bacteria–99.9%. While such treatment is possible only during the growing season, it could be useful at summer cottages, camping areas, resorts and roadside rest areas. Marsh treatment systems are inexpensive to operate and virt

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1976.tb03133.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTLocal ground‐water pollution problems are often associated with disposal of sewage from remote recreational areas. Ground water in these areas is routinely used for domestic purposes without treatment. Sewage treatment facilities are often prohibitively expensive. Transporting sewage to municipal sewage treatment facilities is often equally costly, or adequate facilities are not available.A soil incorporation method was tested at two field sites in Michigan's Upper Peninsula to evaluate its impact on ground‐water quality; Liquefied campground sewage was injected at 15 cm (6 in.) depths using a liquid manure system. Average dosage levels were 2.7 metric tons per hectare (1.2 ton/acre) of dry sewage solids. The application rate was equivalent to a fertilization rate of 116 kg/ha (104 Ib/a) of total nitrogen. Field tests were conducted on adjacent strips of Kalkaska sand soils in 1973, 1974, and 1975.Changes in ground‐water quality in the zone immediately beneath the water table were evaluated by analyzing samples from randomly located wells. Test wells were located directly beneath the treated area and up to 30.5 m (100 ft.) away in the direction of ground‐water flow. Nitrate levels in ground water at 3.6 m (12 ft.) depths were higher than control levels from the treated zone to the limit of the test well sampling. Levels of nitrate did not exceed the limits for potable water (10 mg/1 NO3‐N). No fecal coliform organisms were detected in ground‐water samples. Laboratory tests of the filtration capability of the A and B horizons indicated a high level of filtration of polio virus.Fertilization with sewage increased the biomass of native herbaceous vegetation by 410 percent. Nitrogen content of the treated vegetation was 63 percent above controls. Approximately 48 percent of the added nitrogen fertilizer was incorporated in herbaceous foliage at the end of the first growing season.Site selection guidelines for use by National Forests include remote location of incorporation sites, no potable‐water sources within one‐half mile downgradient from the site, infiltration rates between 5 and 25 inches per hour, slopes less than 5 percent, and dosage rates which will not exceed 50 kg/ha (56 lb/a) of mineralized nitrogen per year. Injection depths should provide complete soil coverage but sewage should be placed above the B horizon for maximum use of nutrients by plants.The soil incorporation method has been approved for selected sites by the Michigan Department of Natural Resources and the U.S. Environmental Protection Agency, with ground‐water monitoring requ

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1976.tb03134.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTEnvironmental effects of feedlot location and related land disposal operations can be minimized if proper knowledge of hazardous conditions are known and appropriate protective steps taken. Common guidelines often do not apply because of differing physical characteristics of local areas.Analyses of various parameters within a soil profile beneath a feedlot revealed none of the chemical constituent present in high concentrations below the 23‐foot depth. In areas where shallow ground water was less than 5 feet from the surface, the ground water was found to be affected by the feedlot. Other hazardous areas in feedlot location are flood‐prone areas, areas of surface bedrock, and areas of excessive slope.For land disposal operations, loading rates and frequency of application of feedlot waste should be adjusted in accordance with soil permeability, depth to ground water, and irrigation practices to minimize detrimental effects on ground‐water qu

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1976.tb03135.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTOver the last few years rises in the nitrate content of ground water from wells and springs in the principal aquifers of the United Kingdom have been observed. In a number of cases the concentrations have exceeded the WHO lower recommended limit. In order to determine the reason for the rise, to assess whether it will continue and the eventual nitrate levels, the Water Research Centre has undertaken an extensive programme of drilling and sampling on the Chalk and Bunter Sandstone, and by August 1976, twenty‐two sites had been examined. This work has established that high nitrate concentrations (peaks up to 60 mg/l NO3‐N have been observed) are present in the unsaturated aquifers at fertilized arable/ley sites. At unfertilized grassland sites nitrate concentrations are low (less than 4 mg/l NO3‐N) and below fertilized established grassland values are in the intermediate range. At one farm site near Winchester, models to predict the rate of movement of nitrate through the unsaturated and saturated Chalk have been developed. These suggest that the nitrate levels at this site will remain at an essentially constant value of about 4 mg/l NO3‐N until the late 1970's when they will rise progressively to about 4 mg/l NO3‐N. The models have been checked against tritium data and the approach is now being extended to ot

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1976.tb03136.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTIn 1973, the Suffolk County Department of Environmental Control in cooperation with Cornell University began a study on nitrogen (N) fertilization of potatoes and turfgrasses. The research and demonstration project has shown that current practices result in substantial N losses; and, in many cases, excessive use of N reduces crop yields and turf quality. Annual N losses of 50 lbs. per acre (55.5 kg‐N/ha) are sufficient to cause a concentration in the aquifer's surface layer of 10 mg/1 nitrate‐N (New York State Drinking Water Standard).The eastern portion of Long Island supports a productive agricultural industry whose main crop is potatoes. Ground‐water surveys have shown that the aquifer system of this area is contaminated with nitrate nitrogen. The average potato grower applies 200 to 250 lb‐N/a (222 to 278 kg‐N/ha) at planting time; and depending upon a number of factors, N recovered in harvested tubers varies from 75 to 150 lb‐N/a (83 to 167 kg‐N/ha). Losses to the ground water could vary from 50 to 175 lb‐N/a (55.5 to 194 kg‐N/ha). The study has shown that the application of 150 lb‐N/a (167 kg‐N/ha) can still maintain maximum potato yields and keep the N loss to ground water below 50 lb‐N/a (55.5 kg‐N/ha) by improving nitrogen‐use efficiency. This is done through splitting N applications so that one‐third to one‐half is applied at planting and the remainder is applied prior to the period of rapid crop growth and nutrient uptake. On‐farm demonstration plots are being used to convince growers to reduce N rates and adopt more efficient application methods.The western portions of Long Island are highly urbanized and turfgrasses may be fertilized at rates up to 350 lb‐N/a (389 kg‐N/ha). Potential leaching losses are high for turfgrass as N is not recovered in harvested plant materials. Experiments are underway to establish rates of biomass N buildup under several fertilization regimes. Preliminary results indicate that N‐use efficiency increases with more frequent but smaller N applications. Encouraging the use of low maintenance turf species ap

ISSN:0017-467X    

DOI:10.1111/j.1745-6584.1976.tb03137.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY