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991.
Saud A. Amer Timothy O. Keefer Mark A. Weltz David C. Goodrich Leslie B. Bach 《Journal of the American Water Resources Association》1994,30(1):69-83
ABSTRACT: Certain physical and chemical properties of soil vary with soil water content. The relationship between these properties and water content is complex and involves both the pore structure and constituents of the soil solution. One of the most economical techniques to quantify soil water content involves the measurement of electrical resistance of a dielectric medium that is in equilibrium with the soil water content. The objective of this research was to test the reliability and accuracy of fiberglass soil-moisture electrical resistance sensors (ERS) as compared to gravimetric sampling and Time Domain Reflectometry (TDR). The response of the ERS was compared to gravimetric measurements at eight locations on the USDA-ABS Walnut Gulch Experimental Watershed. The comparisons with TDR sensors were made at three additional locations on the same watershed. The high soil rock content (≥45 percent) at seven locations resulted in consistent overestimation of soil water content by the ERS method. Where rock content was less than 10 percent, estimation of soil water was within 5 percent of the gravimetric soil water content. New methodology to calibrate the ERS sensors for rocky soils will need to be developed before soil water content values can be determined with these sensors. 相似文献
992.
John K Stamer Robert B. Swanson Paul R. Jordan 《Journal of the American Water Resources Association》1994,30(5):823-831
ABSTRACT: A synoptic sampling of five surface-water sites in central Nebraska was conducted by the U.S. Geological Survey as part of its National Water-Quality Assessment Program during storm runoff in May 1992 to relate transport, yields, and concentrations of atrazine to environmental setting. Atrazine was the most extensively applied pesticide in the study unit. Atrazine transport was related to the size of contributing drainage area, quantity of atrazine applied, amount of precipitation, and volume of stream-flow. Estimated yields and mean concentrations of atrazine were related to the percentage of cropland in a drainage area. The largest estimated yields and mean concentrations of atrazine in surface water were associated from drainage areas with the highest percentage of cropland, and the smallest was associated with the smallest amount of cropland. Atrazine concentrations increased as streamflow increased but decreased at or near the time of peak streamflows, perhaps due to dilution. Atrazine concentrations then increased and remained elevated far into the stream recession. Atrazine is a regulated contaminant in finished public-water supplies. Large concentrations of atrazine could affect the management of public-water supplies because atrazine remains in solution in contrast to many other pesticides that are more easily removed. 相似文献
993.
Lawrence B. Cahill 《环境质量管理》1994,4(2):71-81
Both opening and closing conferences are crucial elements of an effective environmental audit program. As many firms reengineer their auditing process, focusing on the beginning and end points of the on-site process makes eminent sense. This article discusses a variety of issues that often arise during the preparation and conduct of opening and closing conferences that can ultimately affect the success of the audit. 相似文献
994.
B. Bowonder 《The Environmentalist》1985,5(2):89-103
Summary The author summarizes the events of the Bhopal disaster as they are currently known, and draws a number of very important conclusions regarding safety procedures. These have implications for all developing countries.Dr. B. Bowonder is Chairman of the Centre for Energy, Environment and Technology at the Staff College and, as a regular contributor to this journal, he was invited to analyze the Bhopal incident. 相似文献
995.
External threats to the environmental integrity of Glacier National Park, Montana, USA, fit into three categories: adverse land use practices adjacent to the Park, air pollution, and water pollution. This article identifies and evaluates the laws that Glacier National Park officials might rely upon to protect the Park against these external threats. The article also assesses the available scientific information relating to external threats, and it identifies additional information needed to establish a legal basis for challenging the threats. 相似文献
996.
Coastal wetlands are a valuable resource to North Carolina, USA, representing important habitat for marine organisms and providing flood control areas and buffer zones from marine storms. An analysis of wetland development trends in coastal North Carolina from 1970 to 1984 was conducted using over 3000 files containing 15 years of permitting records. The total amount of coastal wetland area altered due to authorized development under the Coastal Area Management Act (CAMA), the Dredge and Fill Law, and Section 404 of the Federal Water Pollution Control Act is 1740 ha. This represents nearly 2% of the salt marsh wetlands along the coast of North Carolina. The number of permits issued steadily increased during the 1980s; however, the total amount of wetland loss decreased each year. A few large projects in the early 1970s accounted for nearly 70% of all wetland area developed during the 15-year period. Nearly two-thirds of all projects involving wetland destruction involved impacts on high marsh ecosystems. Bulkheads, canals, and filling activities made up 80% of the projects requiring permits; 62% of the permits were issued to private landowners, but this group accounted for only 16% of the losses of wetland area. Utility companies, which accounted for less than 1% of the permits issued, were responsible for 46% of the permitted wetland loss during the 15-year study period. Future studies should address agriculture and forestry practices which are exempt under CAMA laws and therefore their effects on wetland alteration have not been quantified. 相似文献
997.
Robert C. Borden Philip B. Bedient 《Journal of the American Water Resources Association》1987,23(4):629-636
ABSTRACT: A three well injection-production test was performed at the United Creosoting Company (UCC) site in Conroe, Texas, to estimate the effective in situ retardation factors for adsorption and to evaluate the significance of biotransformation in limiting the transport of polycydic aromatics present in the shallow aquifer. The field test was also used as a model to determine if this type of testing would be feasible at other hazardous waste sites. During the test, chloride, a non-reactive tracer and two organic compounds, naphthalene and paradichlorobenzene (pDCB), were injected into a center well for 24 hours followed by clean ground water for six days. Ground water was continuously produced from two adjoining wells and monitored to observe the breakthrough of these compounds. Data from the test were analyzed by comparing the statistical moments of the chloride and organics distributions. Retardation factors for naphthalene and pDCB were estimated to be 1.03 and 0.97 by comparison of the statistical moments. A significant loss of naphthalene and pDCB was also observed during the three well test, apparently due to biotransformation. These results suggest that biotransformation is the major process limiting the transport of naphthalene and similar compounds at the UCC site. 相似文献
998.
Roger B. Long 《Journal of the American Water Resources Association》1987,23(6):1117-1124
ABSTRACT: Pressure is increasing in the western United States to reallocate water from irrigated agriculture to other competitive uses. Since water is normally allocated through water rights and not necessarily by the price system, the question of economic efficiency is a continual concern. Study results show that returns per acre-foot of water used in western irrigation are quite high and are closely tied to the livestock industry. Returns per acre-foot of water used for crops ranged from $60 to $1,500. When water was used to support livestock, returns per acre-foot ranged from $100 to $600. Clearly, losses of water supply that reduced irrigation production could also lower farm income significantly. Estimated returns also show what alternative uses would have to pay for water under competitive market conditions. Production elasticities are also shown for various states. 相似文献
999.
Fishermen were aggregated into high-, mid-, and low-consumptive groups according to the importance they placed on catching fish. Analysis of variance indicated that each consumptive group was unique in the importance it placed on other fish-related variables. Low-consumptive fishermen rated most other aspects of the fishing experience, such as interacting with nature, relaxation, and escaping the daily routine, more important than did high-consumptive fishermen. Low-consumptive fishermen also fished more frequently and were generally more satisfied with their most recent fishing trip than were high-consumptive-oriented fishermen. The three groups can be viewed as different fishing constituencies. By understanding their characteristics, we can gain additional insights into the impacts of management decisions on recreational fishermen and their experiences. 相似文献
1000.
B. BOWONDER Chairman S. S. R. PRASAD Project Associate N. V. M. UNNI Head 《Natural resources forum》1986,10(1):5-16
The price of fuelwood has been increasing at a rate higher than that of the consumer price index in most of the major urban centres of India. Today, in terms of cost per unit of energy delivered, fuelwood is more than twice as expensive as kerosene for cooking. This has immense public policy implications. A number of complementary policy interventions are needed so that forests can be saved and the stability of energy supplies can be achieved in developing countries. 相似文献