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排序方式: 共有1188条查询结果,搜索用时 15 毫秒
31.
Daniel J. Bain Erin M. Copeland Marion T. Divers Marijke Hecht Kristina G. Hopkins Justin Hynicka Michael Koryak Mary Kostalos Lisa Brown Emily M. Elliott Joseph Fedor Michele Gregorich Brady Porter Brenda Smith Christopher Tracey Margaret Zak 《Journal of the American Water Resources Association》2014,50(6):1608-1621
Urban stream restoration continues to be used as an ecological management tool, despite uncertainty about the long‐term sustainability and resilience of restored systems. Evaluations of restoration success often focus on specific instream indicators, with limited attention to the wider basin or parallel hydrologic and geomorphic process. A comprehensive understanding of urban stream restoration progress is particularly important for comparisons with nonurban sites as urban streams can provide substantial secondary benefits to urban residents. Here, we utilize a wide range of indicators to retrospectively examine the restoration of Nine Mile Run, a multi‐million dollar stream restoration project in eastern Pittsburgh (Pennsylvania, USA). Examination of available continuous hydrological data illustrates the high cost of failures to incorporate the data into planning and adaptive management. For example, persistent extreme flows drive geomorphic degradation threatening to reverse hydrologic connections created by the restoration and impact the improved instream biotic communities. In addition, human activities associated with restoration efforts suggest a positive feedback as the stream restoration has focused effort on the basin beyond the reach. Ultimately, urban stream restoration remains a potentially useful management tool, but continued improvements in post‐project assessment should include examination of a wider range of indicators. 相似文献
32.
Protected areas are integral to the global effort to conserve biodiversity, and, over the past two decades, protected area managers have begun to recognize that conservation objectives are next to impossible to achieve without considering the needs and concerns of local communities. Incentive-based programs (IBPs) have become a favored approach to protected area management, geared at fostering local stewardship by delivering benefits tied to conservation to local people. Effective IBPs require benefits to accrue to and be recognized by those experiencing the greatest consequences as a result of the protected area, and those likely to continue extractive activities if their livelihood needs are compromised. This research examines dispersal of IBP benefits, as perceived by local residents in Nepal's Annapurna Conservation Area. Results reported here are based on questionnaire interviews with 188 households conducted between September and December 2004. Results indicate that local residents primarily identify benefits from social development activities, provisions for resource extraction, and economic opportunities. Overall, benefits have been dispersed equally to households in villages on and off the main tourist route, and regardless of a household's participation in tourism. However, benefits are not effectively targeted to poorer residents, those highly dependent on natural resources, and those experiencing the most crop damage and livestock loss from protected wildlife. This article provides several suggestions for improving the delivery of conservation incentives. 相似文献
33.
Evolution of a Mediterranean Coastal Zone: Human Impacts on the Marine Environment of Cape Creus 总被引:1,自引:0,他引:1
This study presents an integrated analysis of the evolution of the marine environment and the human uses in Cape Creus, a
Mediterranean coastal area where intense commercial fisheries and recreational uses have coexisted over the last fifty years.
The investigation synthesizes the documented impacts of human activities on the marine environment of Cap de Creus and integrates
them with new data. In particular, the evolution of vulnerable, exploited species is used to evaluate the fishing impacts.
The effects of area protection through the establishment of a marine reserve in the late 1990s and the potential climate change
impacts are also considered. The evolution of the human uses is marked by the increasing socioeconomic importance of recreational
activities (which affect species and habitats) in detriment to artisanal and red coral fisheries (which principally affect
at a species level). Overall, populations of sedentary, vulnerable exploited species, hard sessile benthic invertebrates,
and ecologically fragile habitats, such as seagrass meadows, the coralligenous and infralittoral algal assemblages have been
the most negatively impacted by anthropogenic activities. Albeit human uses currently constitute the largest negative impact
on the marine environment of Cap de Creus, climate change is emerging as a key factor that could have considerable implications
for the marine environment and tourism activities. The establishment of the marine reserve appears to have had little socioeconomic
impact, but there is some evidence that it had some positive biological effects on sedentary, littoral fishes. Results demonstrate
that the declaration of a marine reserve alone does not guarantee the sustainability of marine resources and habitats but
should be accompanied with an integrated coastal management plan. 相似文献
34.
George N. Zaimes Richard C. Schultz Thomas M. Isenhart 《Journal of the American Water Resources Association》2008,44(4):935-947
Abstract: Phosphorus and sediment are major nonpoint source pollutants that degrade water quality. Streambank erosion can contribute a significant percentage of the phosphorus and sediment load in streams. Riparian land‐uses can heavily influence streambank erosion. The objective of this study was to compare streambank erosion along reaches of row‐cropped fields, continuous, rotational and intensive rotational grazed pastures, pastures where cattle were fenced out of the stream, grass filters and riparian forest buffers, in three physiographic regions of Iowa. Streambank erosion was measured by surveying the extent of severely eroding banks within each riparian land‐use reach and randomly establishing pin plots on subsets of those eroding banks. Based on these measurements, streambank erosion rate, erosion activity, maximum pin plot erosion rate, percentage of streambank length with severely eroding banks, and soil and phosphorus losses per unit length of stream reach were compared among the riparian land‐uses. Riparian forest buffers had the lowest streambank erosion rate (15‐46 mm/year) and contributed the least soil (5‐18 tonne/km/year) and phosphorus (2‐6 kg/km/year) to stream channels. Riparian forest buffers were followed by grass filters (erosion rates 41‐106 mm/year, soil losses 22‐47 tonne/km/year, phosphorus losses 9‐14 kg/km/year) and pastures where cattle were fenced out of the stream (erosion rates 22‐58 mm/year, soil losses 6‐61 tonne/km/year, phosphorus losses 3‐34 kg/km/year). The streambank erosion rates for the continuous, rotational, and intensive rotational pastures were 101‐171, 104‐122, and 94‐170 mm/year, respectively. The soil losses for the continuous, rotational, and intensive rotational pastures were 197‐264, 94‐266, and 124‐153 tonne/km/year, respectively, while the phosphorus losses were 71‐123, 37‐122, and 66 kg/km/year, respectively. The only significant differences for these pasture practices were found among the percentage of severely eroding bank lengths with intensive rotational grazed pastures having the least compared to the continuous and rotational grazed pastures. Row‐cropped fields had the highest streambank erosion rates (239 mm/year) and soil losses (304 tonne/km/year) and very high phosphorus losses (108 kg/km/year). 相似文献
35.
Linking Nitrogen Export to Landscape Heterogeneity: The Role of Infrastructure and Storm Flows in a Mediterranean Urban System 总被引:1,自引:0,他引:1 下载免费PDF全文
James B. McConaghie Mary L. Cadenasso 《Journal of the American Water Resources Association》2016,52(2):456-472
Urban ecosystems are often sources of nonpoint source (NPS) nitrogen (N) pollution to aquatic ecosystems. However, N export from urban watersheds is highly variable. Examples of densely urbanized watersheds are not well studied, and these may have comparatively low export rates. Commonly used metrics of landscape heterogeneity may obscure our ability to discern relationships among landscape characteristics that can explain these lower export rates. We expected that differences not often captured by these metrics in the relative cover of vegetation, structures, and impervious surfaces would better explain observed variation in N export. We examined these relationships during storms in residential watersheds. Contrary to expectations, land cover did not directly predict variation in N or water export. Instead, N export was strongly linked to drainage infrastructure density. Our research highlights the role of fine‐scaled landscape attributes, mainly infrastructure, in explaining patterns of N export from densely urbanized watersheds. Changes to hydrologic flow paths by infrastructure explained more variation in N export than land cover. Our findings support further development of landscape ecological models of urban N export that focus on hydrologic modification by infrastructure rather than traditional landscape measures such as land use, as indicators for evaluating patterns of NPS nitrogen pollution in densely urbanized watersheds. 相似文献
36.
Bruce K. Ferguson 《Journal of the American Water Resources Association》2016,52(5):1238-1250
Urban stormwater practices are individually diverse, but they are components of an overall urban watershed system. This study proposes a conceptual model of that system, including its component spatial areas, their arrangement along the flow route, and their associations with urban land uses and values. The model defines three spatial areas along the flow route which have evolved over time into their present forms: (1) the source area, which is arranged and furnished primarily or entirely for human use, accommodation, and comfort; (2) the perimeter area, where specialized stormwater facilities carry away source‐area runoff or buffer downstream areas from its impacts; and (3) the downstream area, which receives the discharges from the perimeter or directly from the source area. Each area presents a specific combination of stormwater features and human interactions, and excludes others. Considering stormwater flows and functions in the context of physical urban spaces brings into view the spaces’ urban structures and interacting agendas. This model allows practitioners to navigate conceptually through the system, and to focus appropriate objectives and structures on each project site. 相似文献
37.
Coupling of the Water Cycle with Patterns of Urban Growth in the Baltimore Metropolitan Region,United States 下载免费PDF全文
Aditi S. Bhaskar Claire Jantz Claire Welty Scott A. Drzyzga Andrew J. Miller 《Journal of the American Water Resources Association》2016,52(6):1509-1523
Regional municipal water plans typically do not recognize complex coupling patterns or that increased withdrawals in one location can result in changes in water availability in others. We investigated the interaction between urban growth and water availability in the Baltimore metropolitan region where urban growth has occurred beyond the reaches of municipal water systems into areas that rely on wells in low‐productivity Piedmont aquifers. We used the urban growth model SLEUTH and the hydrologic model ParFlow.CLM to evaluate this interaction with urban growth scenarios in 2007 and 2030. We found decreasing groundwater availability outside of the municipal water service area. Within the municipal service area we found zones of increasing storage resulting from increased urban growth, where reduced vegetation cover dominated the effect of urbanization on the hydrologic cycle. We also found areas of decreasing storage, where expanding impervious surfaces played a larger role. Although the magnitude of urban growth and change in water availability for the simulation period were generally small, there was considerable spatial heterogeneity of changes in subsurface storage. This suggests that there are locally concentrated areas of groundwater sensitivity to urban growth where water shortages could occur or where drying up of headwater streams would be more likely. The simulation approach presented here could be used to identify early warning indicators of future risk. 相似文献
38.
The objective of our study was to identify how actors from the main socio-economic sectors perceive their interactions and impacts on a sensitive wetland in an arid climate, specifically the salt pans of Chott Merouane in Algeria. The results revealed that there are three main economic stakes including agriculture, livestock production and salt mining, each activity providing a great benefit for local and national populations. The local population perceived that the current activities are conducted in such a way that they created conflict between socio-economic sectors and caused a threat for long term sustainability of the wetlands. The results highlighted the need to initiate an integrated management approach between the different sectors and to develop a shared vision for the territory. 相似文献
39.
Jaakko Paasivirta Seija Sinkkonen Vladimir Nikiforov Fedor Kryuchkov Erkki Kolehmainen Katri Laihia Arto Valkonen Manu Lahtinen 《Environmental science and pollution research international》2009,16(2):191-205
Background, aims, and scope Since toxaphene (polychlorocamphene, polychloropinene, or strobane) mixtures were applied for massive insecticide use in the
1960s to replace the use of DDT, some of their congeners have been found at high latitudes far away from the usage areas.
Especially polychlorinated bornanes have demonstrated dominating congeners transported by air up to the Arctic areas. Environmental
fate modeling has been applied to monitor this phenomenon using parallel zones of atmosphere around the globe as interconnected
environments. These zones, shown in many meteorological maps, however, may not be the best way to configure atmospheric transport
in air trajectories. The latter could also be covered by connecting a chain of simple model boxes. We aim to study this alternative
approach by modeling the trajectory chain using catchment boxes of our FATEMOD model. Polychlorobornanes analyzed in biota
of the Barents Sea offered one case to study this modeling alternative, while toxaphene has been and partly still is used
massively at southern East Europe and around rivers flowing to the Aral Sea.
Materials and methods Pure model substances of three polychlorobornanes (toxaphene congeners P26, P50, and P62) were synthesized, their environmentally
important thermal properties measured by differential scanning calorimetry, as evaluated from literature data, and their temperature
dependences estimated by the QSPR programs VPLEST, WATSOLU, and TDLKOW. The evaluated property parameters were used to model
their atmospheric long-range transport from toxaphene heavy usage areas in Ukraine and Aral/SyrDarja/AmuDarja region areas,
through East Europe and Northern Norway (Finnmarken) to the Barents Sea. The time period used for the emission model was June
1997. Usual weather conditions in June were applied in the model, which was constructed by chaining FATEMOD model boxes of
the catchment’s areas along assumed maximal air flow trajectories. Analysis of the three chlorobornanes in toxaphene mixtures
function as a basis for the estimates of emission levels caused by its usage. High estimate (A) was taken from contents in
a Western product chlorocamphene and low estimate (B) from mean contents in Russian polychloroterpene products to achieve
modeled water concentrations. Bioaccumulation to analyzed lipid of aquatic biota at the target region was estimated by using
statistical calculation for persistent organic pollutants in literature.
Results The results from model runs A and B (high and low emission estimate) for levels in sea biota were compared to analysis results
of samples taken in August 1997 at Barents Sea. The model results (ng g−1 lw): 4–95 in lipid of planktovores and 7–150 in lipid of piscivores, were in fair agreement with the analysis results from
August 1997: 21–31 in Themisto libellula (chatka), 26–42 in Boreocadus saida (Polar cod), and 5–27 in Gadus morhua (cod) liver.
Discussion The modeling results indicate that the application of chained simple multimedia catchment boxes on predicted trajectory is
a useful method for estimation of volatile airborne persistent chemical exposures to biota in remote areas. For hazard assessment
of these pollutants, their properties, especially temperature dependences, must be estimated by a reasonable accuracy. That
can be achieved by using measurements in laboratory with pure model compounds and estimation of properties by thermodynamic
QSPR methods. The property parameters can be validated by comparing their values at an environmental temperature range with
measured or QSPR-estimated values derived by independent methods. The chained box method used for long-range air transport
modeling can be more suitable than global parallel zones modeling used earlier, provided that the main airflow trajectories
and properties of transported pollutants are predictable enough.
Conclusions Long-range air transport modeling of persistent, especially photo-resistant organic compounds using a chain of joint simple
boxes of catchment’s environments is a feasible method to predict concentrations of pollutants at the target area. This is
justified from model results compared with analytical measurements in Barents Sea biota in August 1997: three of six modeled
values were high and the other three low compared to the analysis results. The order of magnitude level was similar in both
modeled (planktovore and piscivore) and observed (chatka and polar cod) values of lipid samples. The obtained results were
too limited to firm validation but are sufficient to justify feasibility of the method, which prompts one to perform more
studies on this modeling system.
Recommendations and perspectives For assessment of the risk of environmental damages, chemical fate determination is an essential tool for chemical control,
e.g., for EU following the REACH rules. The present conclusion of applicability of the chained single-box multimedia modeling
can be validated by further studies using analyses of emissions and target biota in various other cases. To achieve useful
results, fate models built with databases having automatic steps for most calculations and outputs accessible to all chemical
control professionals are essential. Our FATEMOD program catchments at environments and compound properties listed in the
database represent a feasible tool for local, regional, and, according our present test results, for global exposure predictions.
As an extended use of model, emission estimates can be achieved by reversed modeling from analysis results of samples corresponding
to the target area.
This article is dedicated to the memory of Professor Alexander B Terentiev (who passed away in November 2006), our true friend.
With his Institute of Organo-Element Compounds, Russian Academy of Science, Moscow, he was an important main organizer of
the six joint Finnish–Russian seminars (every third year since 1989) on the field (‘Chemistry and Ecology of Organo-Element
Compounds’). He prompted us especially to search properties and environmental fates for various polyhalogen compounds. We
remember him for his friendly character and great sense of humor. 相似文献
40.
以呈贡县大渔乡为案例,调查分析了区域农村固体废物的来源、产生量、成分和处理处置现状,引入了固体废弃物潜在污染负荷指数。 相似文献