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61.
The goal of this research was to evaluate the relative effects of root density, freeze/thaw cycling, and soil properties on the erodibility and critical shear stress of streambanks. The erodibility and critical shear stress of rooted bank soils were measured in situ at 25 field sites using a submerged jet test device; several soil, vegetation, and stream chemistry characteristics shown to influence soil erosion were also assessed. Multiple linear regression analysis was conducted to determine those factors that most influenced streambank erodibility and the relative impact of riparian vegetation. Study results indicated that soil erosion is a complex phenomenon that depends primarily on soil bulk density. Freeze/thaw cycling, soil antecedent moisture content, the density of roots with diameters of 2 to 20 mm, soil texture, and the interaction of soil pore water and stream water had a significant impact on soil erodibility and critical shear stress, depending on soil type. Riparian vegetation had multiple significant effects on soil erodibility. In addition to reducing soil erodibility through root reinforcement, the streamside vegetation affected soil moisture and altered the local microclimate, which in turn affected freeze/thaw cycling (FTC). This study represents the first in situ testing of the erodibility of vegetated streambanks and provides a quantitative analysis on the effects of vegetation on streambank erosion, relative to other soil physical and chemical parameters. 相似文献
62.
Theresa M. Groth Allan Curtis Emily Mendham Eric Toman 《Journal of Environmental Planning and Management》2017,60(4):628-646
Multifunctional rural landscapes are often characterised by contrasting values, land uses and land management practices of rural property owners. It seems these trends are, in part, an expression of rural landholder's identification as farmers. Existing typologies of rural landholders seldom take into account occupational identity. Research discussed in this paper addresses that gap. The objective was to apply the collective occupational identity construct to address the challenges of profiling rural landholders and test its effectiveness at distinguishing between different types of landholders. A 12-item scale was used to explore the extent rural landholders in south-eastern Australia held an agricultural producer identity. Cluster analysis resulted in the creation of four clusters of rural landholders with distinctive characteristics, suggesting the approach can provide researchers with a theoretically sound construct and practitioners with a useful tool as they attempt to better understand and engage rural landholders in sustainable agriculture. 相似文献
63.
Chuan Wang Samuel Nordgren Bo Lindblom Stefan Savonen Theresa Hedpalm Mikael Larsson Robert Hansson 《Journal of Cleaner Production》2010,18(9):944-951
LKAB Malmberget is a Swedish mining site located at Malmberget, Sweden. Seven boiler centers are located in the north part of Malmberget. There are no connections in between these boiler centers, meaning that it is a decentralized heating system. The heat generated is used to heat up buildings and for mine ventilation air mainly during the cold periods. The heat is mainly provided from electric and oil boilers. However, most boilers under use are over 20 years old, and it is time to retrofit the boiler system and infrastructure. The purpose of this work is to design and optimize the heating system by introducing an integrated concept to minimize the heat production cost.An optimization model based on the mixed integer linear programming (MILP) has been developed. Several technical options have been considered in a new centralized heating system. The optimization principle is based on two kinds of perspectives: current price and external costs. With consideration of environmental and health damage from society concerns point of view, instead of environmental taxes in the current price perspective, the monetary values of externalities due to pollutants such as CO2, NOx, SO2 and particulates emitted from the heating system are included. On the basis of data input and assumptions, modeling results indicate that a lower cost could be achieved when a waste heat recovery boiler is installed at the older pelletization plant to recover sensible heat from flue gas. This technical option is the best solution or at least contributes to the best solution in all optimization results. Including the externality cost is useful for making fair evaluation of the social-environmental impacts of the alternatives. 相似文献
64.
As a result of Structural Adjustment Programme from the 1980s, many developing countries have experienced an increase in resource extraction activities by international and transnational corporations. The work reported here examines the perceived impacts of gold mining at the community level in the Wassa West District of Ghana, Africa and discusses those perceived impacts in the context of globalization processes and growing multinational corporate interest in Corporate Social Responsibility (CSR). Interview data compared community members' perceptions with those of company representatives in three communities. The results indicate that communities held companies responsible for a series of economic, social, and environmental changes. While recognizing some of the benefits brought by the mines, communities felt that the companies did not live up to their responsibility to support local development. Companies responded by denying, dismissing concerns, or shifting blame. Findings from this work show that lack of engagement and action by government agencies at all levels resulted in companies acting in a surrogate governmental capacity. In such situations, managing expectations is key to community-company relations. 相似文献
65.
Transpiration and Root Development of Urban Trees in Structural Soil Stormwater Reservoirs 总被引:2,自引:0,他引:2
Julia Bartens Susan D. Day J. Roger Harris Theresa M. Wynn Joseph E. Dove 《Environmental management》2009,44(4):646-657
Stormwater management that relies on ecosystem processes, such as tree canopy interception and rhizosphere biology, can be
difficult to achieve in built environments because urban land is costly and urban soil inhospitable to vegetation. Yet such
systems offer a potentially valuable tool for achieving both sustainable urban forests and stormwater management. We evaluated
tree water uptake and root distribution in a novel stormwater mitigation facility that integrates trees directly into detention
reservoirs under pavement. The system relies on structural soils: highly porous engineered mixes designed to support tree
root growth and pavement. To evaluate tree performance under the peculiar conditions of such a stormwater detention reservoir (i.e., periodically
inundated), we grew green ash (Fraxinus pennsylvanica Marsh.) and swamp white oak (Quercus bicolor Willd.) in either CUSoil or a Carolina Stalite-based mix subjected to three simulated below-system infiltration rates for
two growing seasons. Infiltration rate affected both transpiration and rooting depth. In a factorial experiment with ash,
rooting depth always increased with infiltration rate for Stalite, but this relation was less consistent for CUSoil. Slow-drainage
rates reduced transpiration and restricted rooting depth for both species and soils, and trunk growth was restricted for oak,
which grew the most in moderate infiltration. Transpiration rates under slow infiltration were 55% (oak) and 70% (ash) of
the most rapidly transpiring treatment (moderate for oak and rapid for ash). We conclude this system is feasible and provides
another tool to address runoff that integrates the function of urban green spaces with other urban needs. 相似文献
66.
Monitoring Plant Phenology Using Digital Repeat Photography 总被引:1,自引:0,他引:1
Repeated observations of plant phenology have been shown to be important indicators of global change. However, capturing the
exact date of key events requires daily observations during the growing season, making phenologic observations relatively
labor intensive and costly to collect. One alternative to daily observations for capturing the dates of key phenologic events
is repeat photography. In this study, we explored the utility of repeat digital photography for monitoring phenologic events
in plants. We provide an illustration of this approach and its utility by placing observations made using repeat digital imagery
in context with local meteorologic and edaphic variables. We found that repeat photography provides a reliable, consistent
measurement of phenophase. In addition, digital photography offers advantages in that it can be mathematically manipulated
to detect and enhance patterns; it can classify objects; and digital photographs can be archived for future analysis. In this
study, an estimate of greenness and counts of individual flowers were extracted by way of mathematic algorithms from the photo
time series. These metrics were interpreted using meteorologic measurements collected at the study site. We conclude that
repeat photography, coupled with site-specific meteorologic measurements, could greatly enhance our understanding environmental
triggers of phenologic events. In addition, the methods described could easily be adopted by citizen scientists and the general
public as well as professionals in the field. 相似文献
67.
While farming has been the subject of frequent critical analysis with respect to its environmental impacts, including its greenhouse gas emissions, there has been relatively little consideration of the potentially positive role of agriculture in responding to a future greatly influenced by climate change. One possible realm for agriculture to contribute successfully to this future is through biofuels cultivation. This paper uses the state of Kansas as an example to examine factors that are influencing farmer decision-making during a time of heightened debates about climate and energy. Drawing on interviews with key informants and Kansas farmers, we apply and refine a conceptual model for understanding farmer decisions. We find that farmers have largely positive perceptions of the natural environment. Climate change, especially, is not a salient concern at this time. Factors that appear most likely to influence farmer decisions to adopt a new practice include the relative advantage of that practice and the ability to learn about and discuss it through existing social networks. Successful policy incentives must provide farmers with a continued sense of both independence and contribution to greater societal good. 相似文献
68.
Theresa M. Glomb 《组织行为杂志》2013,34(5):698-713
On the basis of justice and exchange theories, the authors propose that employees offset their levels of work–family conflict (WFC) with their levels of pay satisfaction. Results based on two waves of data indicate that pay satisfaction has a negative relationship with WFC after controlling for actual pay and other work‐related and family‐related variables. Analysis of pay satisfaction dimensions reveals that satisfaction with benefits and pay structure are negatively related to WFC, whereas satisfaction with pay level and pay raise are not. Number of dependents and level of education moderate the relationship between pay satisfaction and WFC; specifically, having more dependents and higher education attenuates the relationship between pay satisfaction and WFC. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
69.
Ecological impacts of water-quality problems have developed in the western United States resulting from the disposal of seleniferous
agricultural wastewater in wetland areas. Overt effects of selenium toxicosis occurred at five areas where deformities of
wild aquatic birds were similar to those first observed at Kesterson National Wildlife Refuge in the west-central San Joaquin
Valley of California. These areas are: Tulare Lake Bed Area, California, Middle Green River Basin, Utah, Kendrick Reclamation
Project Area, Wyoming, Sun River Basin, Montana, and Stillwater Wildlife Management Area, Nevada. Potential for ecological
damage is indicated at six more sites in Oregon, Colorado, the Colorado/Kansas border, and South Dakota out of 16 areas in
11 states where biological tissue data were collected. This conclusion is based on the fact that selenium bioaccumulated in
bird livers to median levels that had exceeded or were in the range associated with adverse reproductive effects. Selenium
concentrations in samples of fish and bird eggs support these conclusions at a majority of these areas. Reason for concern
is also given for the lower Colorado River Valley, although this is not exclusively a conclusion from these reconnaissance
data. Biogeochemical conditions and the extent of selenium contamination of water, bottom sediment, and biota from which this
assessment was made are given here. In a companion paper, the biogeochemical pathway postulated for selenium contamination
to take place from natural geologic sources to aquatic wildlife is defined. 相似文献
70.
Wynn R. Walker Caylord V. Skogerboe Thoms L. Huntzinger 《Journal of the American Water Resources Association》1974,10(5):845-859
ABSTRACT: Urbanizing river basins in the west are encountering serious water quality degradation resulting from the expanded water utilization. In order to avoid aggravating such conditions, water quality controls need to be implemented. The important questions are, therefore, where and how to impose such constraints on the urban and agricultural sectors to achieve the desired level of pollution control. An application of the model developed to address such questions is made in the Utah Lake drainage area of Central Utah as a test of the model's utility. The region is subdivided into five major sub-basins containing both municipal and agricultural water demands. A submodel of each sub-basin is developed which optimizes the water quality control strategies by linking the urban to the agricultural uses and then evaluating the levels of control for each sector. From these results, a cost-effectiveness function for each sub-basin is generated. By jointly considering the cost-effectiveness relationship for each sub-basin, an optimum policy for the entire basin is determined. 相似文献