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511.
Joanna Burger 《Environmental management》1998,22(6):869-876
/ Management of ecosystems has advanced by an improvement in our understanding not only of how ecosystems function, but of how people perceive their functioning and what they consider to be environmental problems within those systems. Central to such management is understanding how people view estuaries. In this article I explore the perceptions and attitudes of people about coastal recreation, environmental problems, and future land use along the New Jersey shore (USA) by interviewing people who attended a duck decoy and craft show on Barnegat Bay. The people who were interviewed engaged in more days of fishing than any other recreational activity and engaged in camping the least. There were significant differences in recreational rates as a function of gender and location of residence, with men hunting and fishing more than women and photographing less than women. Jet skis were perceived as the most severe environmental problem, with chemical pollution, junk, oil runoff and overfishing as second level problems. Birds were perceived as not an environmental problem at all. Fishing, hiking, preservation, and camping ranked as the highest preferred future land uses for the two sites examined (Oyster Creek Nuclear Generating Station, Naval Weapons Station Earle). The preferred future land uses for these two sites, which are not under consideration for land-use changes, were very similar to those of people living near the Department of Energy's Savannah River Site in South Carolina, despite the media attention and considerations of nuclear storage.KEY WORDS: Recreation; Perceptions; Environmental problem; Gender; Land use; Coastal 相似文献
512.
/ Land-based point and diffuse pollution sources in the catchment area of Lake Sapanca, Turkey, were investigated. The present and future distribution of pollution loads were evaluated in terms of nitrogen, phosphorus, biochemical oxygen demand, and pesticides. A methodology for the estimation of pollution loads was presented; most of which were based on "unit loads." Presently domestic and industrial point sources dominate over diffuse sources including fertilizers and pesticides from agricultural use, nutrient loads from forests and meadows, urban runoff, and leachates from unregulated dumps of solid wastes. For the future, the aim of the control action is to maintain the sustainability of the water quality of the lake, at least at the second class of European Community standards. Within this framework; urgent/short-term and medium/long-term control actions will be exercised. In the urgent/short-term stage, simpler and natural ways of treatment will be employed. In the medium/long-term stage an integrated collection and treatment system will be put on operation. After completion of a proposed collection system and treatment plants to handle point sources, the control of diffuse sources will be more significant. Control of diffuse sources for the abatement of further deterioration of water quality then becomes the key issue to be emphasized in the Lake Sapanca catchment area. Diffuse sources control will be achieved by dividing the catchment area into three major protection zones. Use of pesticides and fertilizers on agricultural land and all other activities within these protection zones will be accomplished according to control plans, which will be supervised by an institution established to be responsible of all the activities within the basin.KEY WORDS: Diffuse sources; Land-based pollution; Nutrients; Pesticides; Point sources; Protection zones 相似文献
513.
514.
Xinhao Wang 《Environmental management》1997,21(4):607-615
/ An effective groundwater protection program requires understanding of water flow and contaminant transport processes in the subsurface. Although many mathematical models have been developed to simulate the processes, few actually are used in groundwater protection programs due to the difficulties in data collection, model selection, and model implementation. This study presents a conceptual design of a GIS-supported model selection system that evaluates available data and mathematical models to facilitate groundwater protection programs. Steady-state groundwater and contaminant transport models applied in isotropic aquifers are placed into four classes to simulate conservative or nonconservative contaminant transports in simple or complex geohydrological conditions. After analyzing specific study objectives, available data, and model requirements, the proposed system selects a class of models that can be used in simulation and recommends any need for additional data collection. This study initiates an effort to integrate GIS, mathematical models, and expert knowledge in one system to promote the application of appropriate groundwater models. The new technology of GIS and digital data-base management makes it possible to develop such a system in practice.KEY WORDS: Groundwater models; Geographic information systems 相似文献
515.
/ A study was conducted to determine the extent of nitrogenpollution in agricultural lands in the Lower Fraser River basin of BritishColumbia, Canada. The specific objectives were to determine the distributionof leachable nitrogenand estimate the nitrogen concentration in groundwaterrecharges. Nitrogen and water mass balances were conducted on the entirebasin and on each of the four districts comprising it over the period1971-1991 in intervals of five years. The results indicated that the averagenitrogen concentration in the groundwater recharge for the entire basin rosefrom nondetectable in 1971 to 6 mg/liter in 1991. Estimates for theindividual districts ranged from 4 to 14 mg/liter in Central Fraser and fromnondetectable to 7 mg/liter in Fraser-Cheam and 3 mg/liter in both GreaterVancouver and Dewdney-Alouette. So far, excessive levels of nitrogen areconfined to Central Fraser. Although they have remained within the acceptablerange, nitrogen concentrations in the other three districts have definitelyincreased over the 20-year study period. Sensitivity analyses indicated thatanimal manure and fertilizer had the largest contribution in groundwaterrecharge. Decreasing the rate of manure application to agricultural lands issuggested as the most practical way of reducing nitrogen pollution in CentralFraser.KEY WORDS: Nitrogen balance; Water balance; Sensitivity analysis 相似文献
516.
/ Little attention has been paid to wetland stream morphology in the geomorphological and environmental literature, and in the recently expanding wetland reconstruction field, stream design has been based primarily on stream morphologies typical of nonwetland alluvial environments. Field investigation of a wetland reach of Roaring Brook, Stafford, Connecticut, USA, revealed several significant differences between the morphology of this stream and the typical morphology of nonwetland alluvial streams. Six morphological features of the study reach were examined: bankfull flow, meanders, pools and riffles, thalweg location, straight reaches, and cross-sectional shape. It was found that bankfull flow definitions originating from streams in nonwetland environments did not apply. Unusual features observed in the wetland reach include tight bends and a large axial wavelength to width ratio. A lengthy straight reach exists that exceeds what is typically found in nonwetland alluvial streams. The lack of convex bank point bars in the bends, a greater channel width at riffle locations, an unusual thalweg location, and small form ratios (a deep and narrow channel) were also differences identified. Further study is needed on wetland streams of various regions to determine if differences in morphology between alluvial and wetland environments can be applied in order to improve future designs of wetland channels.KEY WORDS: Stream morphology; Wetland restoration; Wetland creation; Bankfull; Pools and riffles; Meanders; Thalweg 相似文献
517.
ENVIRONMENTAL AUDITING: A Synoptic Approach for Assessing Cumulative Impacts to Wetlands 总被引:1,自引:0,他引:1
/ The US Environmental Protection Agency's Wetlands ResearchProgram has developed the synoptic approach as a proposed method forassessing cumulative impacts to wetlands by providing both a general and acomprehensive view of the environment. It can also be applied more broadly toregional prioritization of environmental issues. The synoptic approach is aframework for making comparisons between landscape subunits, such aswatersheds, ecoregions, or counties, thereby allowing cumulative impacts tobe considered in management decisions. Because there is a lack of tools thatcan be used to address cumulative impacts within regulatory constraints, thesynoptic approach was designed as a method that could make use of availableinformation and best professional judgement. Thus, the approach is acompromise between the need for rigorous results and the need for timelyinformation. It is appropriate for decision making when quantitative,accurate information is not available; the cost of improving existinginformation or obtaining better information is high; the cost of a wronganswer is low; there is a high demand for the information; and the situationcalls for setting priorities between multiple decisions versus optimizing fora single decision. The synoptic approach should be useful for resourcemanagers because an assessment is timely; it can be completed within one totwo years at relatively low cost, tested, and improved over time. Anassessment can also be customized to specific needs, and the results arepresented in mapped format. However, the utility of a synoptic assessmentdepends on how well knowledge of the environment is incorporated into theassessment, relevant to particular management questions.KEY WORDS: Cumulative impact assessment; Landscape ecology; Regionalprioritization 相似文献
518.
Arthur L. Fredeen James T. Randerson N. Michele Holbrook Christopher B. Field 《Journal of the American Water Resources Association》1997,33(5):1033-1039
ABSTRACT: Californian annual grassland on sandstone (moderately fertile) and serpentine (very infertile) soils at the Jasper Ridge Biological Preserve, Stanford, California, were exposed to ambient or elevated (ambient + 36 Pa CO2) atmospheric CO2 in open-top chambers since December 1991. We measured ecosystem evapotranspiration with open gas-exchange systems, and soil moisture with time-domain reflectometry (TDR) over 0–15 cm (serpentine) and 0–30 cm (sandstone) depths, at times of peak above ground physiological activity. Evapotranspiration decreased by 12 to 63 percent under elevated CO2 in three consecutive years in the sandstone ecosystem (p = 0.053, p = 0.162, p = 0.082 in 1992, 1993, and 1994, respectively). In correspondence with decreased evapotranspiration, late-season soil moisture reserves in the sandstone were extended temporally by 10 ± 3 days in 1993 and by 28 ± 11 days in 1994. The effect of elevated CO2 on soil moisture was greater in the drier spring of 1994 (419 mm annual rainfall) than in 1993 (905 mm annual rainfall). In the serpentine ecosystem, evapotranspiration and soil moisture reserves were not clearly affected by elevated CO2. Soil water may be conserved in drought-affected ecosystems exposed to elevated CO2, but the amount of conservation appears to depend on the relative importance of transpiration and soil evaporation in controlling water flux. 相似文献
519.
本文论述了水土水流失对生态环境的影响和对农业生产的危害,阐明增强环境意识,加强水土保持时防止生态恶化,是我国振兴农业的重要性与紧迫性的任务。 相似文献
520.
Robert H. Montgomery Kenneth H. Reckhow 《Journal of the American Water Resources Association》1984,20(1):43-52
ABSTRACT: With the advent of standards and criteria for water quality variables, there has been an increasing concern about the changes of these variables over time. Thus, sound statistical methods for determining the presence or absence of trends are needed. A Trend Detection Method is presented that provides: 1) Hypothesis Formulation - statement of the problem to be tested, 2) Data Preparation - selection of water quality variable and data, 3) Data Analysis - exploratory data analysis techniques, and 4) Statistical Tests - tests for detecting trends. The method is utilized in a stepwise fashion and is presented in a nonstatistical manner to allow use by those not well versed in statistical theory. While the emphasis herein is on lakes, the method may be adopted easily to other water bodies. 相似文献