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161.
Impacts of freshwater wetlands on water quality: A landscape perspective   总被引:5,自引:0,他引:5  
In this article, we suggest that a landscape approach might be useful in evaluating the effects of cumulative impacts on freshwater wetlands. The reason for using this approach is that most watersheds contain more than one wetland, and effects on water quality depend on the types of wetlands and their position in the landscape. Riparian areas that border uplands appear to be important sites for nitrogen processing and retention of large sediment particles. Fine particles associated with high concentrations of phosphorus are retained in downstream wetlands, where flow rates are slowed and where the surface water passes through plant litter. Riverine systems also may play an important role in processing nutrients, primarily during flooding events. Lacustrine wetlands appear to have the least impact on water quality, due to the small ratio of vegetated surface to open water. Examples are given of changes that occurred when the hydrology of a Maryland floodplain was altered.  相似文献   
162.
A study is presented of the months in which the instantaneous annual maximum discharges from 66 watersheds occurred. The 2,052 flood values were measured on areas ranging from 2.4 through 214 square miles. The longest record was 60 years; the three shortest were 20. Pictorial results show both the number of floods for each month and individual discharges relative to the mean flood. A parameter which is weighted in this manner accounts for both the incidence and the magnitude of floods. Peculiarities of flood-timing charts, based on this parameter, are discussed with respect to watershed size, soils, geology, and land use. After anomolous watersheds had been assigned to special categories, flood-timing charts from most records exhibit a regional dichotomy dividing eastern from western Pennsylvania.  相似文献   
163.
The results of this study indicate that manipulations of the pathway grid configuration and landmark placement in a setting cause changes in environmental knowledge. These experimental manipulations were accomplished using a realistic, dynamic simulation technique at the Berkeley Environmental Simulation Laboratory. Measures of environmental knowledge include: memory for incidental information along the simulated urban route, accuracy of route maps, relocation memory for scenes along the route, and questionnaire measures. Data are also presented showing both positive and negative effects of stress from noise on the processes of environmental cognition.  相似文献   
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The purpose of this paper is to analyse the recent behaviour of the US zinc processing industry and the impact of US government policies on it. The first section of the paper is a discussion on the basic structure and conditions of the US zinc processing industry since 1950 and how they have changed. The discussion contains a general presentation of the US zinc market, a detailed look at the behaviour of individual primary zinc processing plants in the USA, Canada, Japan and Western Europe and an analysis of US government policies and their impacts on the US zinc industry. The second section of the paper is a discussion of the factors that have contributed to the decline in US zinc processing capacity and the type of government policy that should be followed in response.  相似文献   
166.
Does religion affect legislators’ behavior on environmental policy in the US? Studies of environmental policy making have not examined this question, although the literature suggests that religion might affect legislative behavior on environmental policy. This study examines the relationship between US House members’ religion and roll-call voting on environmental legislation from 1973 to 2009. It finds significant differences across religious traditions. Legislators’ party and characteristics of constituencies relevant to environmental politics increasingly, but not entirely, mediate these differences.  相似文献   
167.
A sample of 135 female human service professionals completed the Maslach Burnout Inventory (MBI) and the Staff Burnout Scale for Health Professionals (SBS), along with measures of job satisfaction, role stress, self-esteem, alienation, and locus of control. Principal components factor analysis of this battery indicates considerable covariation of self-reported burnout with job dissatisfaction and perceived role stress, and moderate overlap with more general feelings of alienation and low self-esteem. Item factor analysis of the 22 MBI items resulted in two independent factors, one defined by the Emotional Exhaustion and Depersonalization items, the other by the Personal Accomplishment items. Item factoring of the SBS produced one large factor which was highly correlated with the MBI exhaustion-depersonalization factor. Implications of these findings for the construct validity of the MBI and SBS are discussed.  相似文献   
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