首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 67 毫秒
1.
Concentrations of Fe and 12 trace elements in peat from ombrotrophic bogs were used to estimate the atmospheric deposition of these elements on a temporal and spatial scale. Peat samples were collected at 21 different sites in Norway encompassing large geographical differences in marine influence and air pollution. The study demonstrates that surface peat is an excellent medium to study geographical differences in heavy metal deposition, provided that effects of the surface plant cover are properly considered. Long-range atmospheric transport of pollutants is the main source for As, Cd, Pb, Sb, and Zn, and to a lesser extent for Cu and Se. Biogenic emissions from the ocean appear to be the main source of Se to the peat. The metals Co, Cr, Fe, and Ni are mainly associated with wind-blown local soil dust. Surface enrichment of Mn, and in part Zn, is mainly caused by nutrient circulation between the surface peat and vascular plants growing on it. Deposition of marine salts appears to be the main reason for lower Mn concentrations in the peat near the coast.  相似文献   

2.
Trees have been widely quoted as effective scavengers of both gaseous and particulate pollutants from the atmosphere. Recent work on the deposition of urban aerosols onto woodland allows the effect of tree planting strategies on airborne aerosol concentrations to be quantified and considered within the planning process. By identifying the potential planting locations in the local authority area, and applying them within a dispersion and deposition model, the potential magnitude of reduction in the ambient concentration of PM(10), achievable through urban tree planting, has been quantified for two UK cities. As part of the Environmental Information Systems for Planners (EISP), flow diagrams, based on planning decisions, have incorporated output from the model to make decisions on land use planning ranging from development plans and strategic planning, to development control. In this way, for any new developments that contribute to the local PM(10) level, the mitigation by planting trees can be assessed, and in some cases, reductions can be sufficient to meet air quality objectives for PM(10).  相似文献   

3.
Monitoring of the ocean environment in southern California, USA, has been conducted by a diverse array of public and private organizations with different motivations, working on a variety of spatial and temporal scales. To create a basis from which to integrate information from these diverse programs, we conducted an inventory of ocean monitoring activities in the Southern California Bight to address the following questions: (1) How much money is being expended annually on marine monitoring programs? (2) Which organizations are conducting the most monitoring? (3) How are resources allocated among the different types of monitoring programs? This inventory focused on programs existing, or those expected to be in existence, for at least 10 years and that were active at any time between 1994 and 1997. For each program identified for inclusion in this study, information was collected on the number of sites, sampling intensity, parameters measured, and methods used. Levels of effort were translated into cost estimates based upon a market survey of local consulting firms. One hundred fourteen marine monitoring programs, conducted by 65 organizations and costing US $31 million annually, were identified. Most of the effort (81 programs, 65% of samples, 70% of costs) was expended by ocean dischargers as part of their compliance with National Pollutant Discharge Elimination System (NPDES) permit requirements. Federal programs (11 programs, 25% of samples, 10% of total expenditures) expended more than state or local government programs. More than one quarter of monitoring expenditures were conducted to measure concentrations and mass of effluent inputs to the ocean. The largest effort expended on receiving water monitoring was for measuring bacteria, followed by sediments, fish/shellfish, water quality, and intertidal habitats. The large level of expenditures by individual agencies has presented opportunities for integrating small, site-specific ocean monitoring programs into regional- and national-scale monitoring and assessment programs.  相似文献   

4.
Monitoring of the ocean environment in southern California, USA, has been conducted by a diverse array of public and private organizations with different motivations, working on a variety of spatial and temporal scales. To create a basis from which to integrate information from these diverse programs, we conducted an inventory of ocean monitoring activities in the Southern California Bight to address the following questions: (1) How much money is being expended annually on marine monitoring programs? (2) Which organizations are conducting the most monitoring? (3) How are resources allocated among the different types of monitoring programs? This inventory focused on programs existing, or those expected to be in existence, for at least 10 years and that were active at any time between 1994 and 1997. For each program identified for inclusion in this study, information was collected on the number of sites, sampling intensity, parameters measured, and methods used. Levels of effort were translated into cost estimates based upon a market survey of local consulting firms. One hundred fourteen marine monitoring programs, conducted by 65 organizations and costing US $31 million annually, were identified. Most of the effort (81 programs, 65% of samples, 70% of costs) was expended by ocean dischargers as part of their compliance with National Pollutant Discharge Elimination System (NPDES) permit requirements. Federal programs (11 programs, 25% of samples, 10% of total expenditures) expended more than state or local government programs. More than one quarter of monitoring expenditures were conducted to measure concentrations and mass of effluent inputs to the ocean. The largest effort expended on receiving water monitoring was for measuring bacteria, followed by sediments, fish/shellfish, water quality, and intertidal habitats. The large level of expenditures by individual agencies has presented opportunities for integrating small, site-specific ocean monitoring programs into regional- and national-scale monitoring and assessment programs.  相似文献   

5.
Desert springs, often the sole sources of water for wildlife and cattle, support wetland and wetland/upland transition ecosystems including rare and endemic species. In the basin and range province in Nevada, USA, springs in the Great Basin and Mojave deserts are sustained by interconnected deep carbonate and shallow basin-fill aquifers which are threatened by proposed groundwater withdrawal to sustain rapidly expanding urban areas, a common problem in arid regions worldwide. This paper draws on historic groundwater data, groundwater modeling, and studies of environmental controls of spring ecosystems to speculate on the potential effects of groundwater withdrawal and water table decline on spring-supported vegetation. The focus is on springs in the Great Basin and Mojave deserts representative of those that may be affected by future, planned groundwater withdrawal. Groundwater withdrawal is expected to reduce spring discharge directly through reduced flows from the shallow basin-fill aquifer or through reduction of the hydraulic head of the deep carbonate aquifer. This flow reduction will truncate the outflow stream, reducing the areal cover of wetland and wetland/upland transition vegetation. Lowering the local water table may also reduce the amount of upland phreatophytic vegetation by causing water levels to drop below plant rooting depths. Percolation of salts to surface soils may be reduced, eventually altering desert shrub cover from halophytes to nonhalophytes. The extent of these effects will vary among springs, based on their distance from extraction sites and location relative to regional groundwater flow paths. On-site monitoring of biotic variables (including cover of selected hygrophytes and phreatophytes) should be a necessary complement to the planned monitoring of local hydrologic conditions.  相似文献   

6.
The objective of this study is to assess how local planning can influence the acidity in the upper forest soil layer. Exceedance of soil acidity was determined by a steady-state mass balance model approach in relation to both present and future deposition. Future deposition scenarios were derived for Stockholm County based on transportation planning. Europe-wide scenarios were derived using the RAINS (Regional Air Pollution Information and Simulation) model. The deposition changes were assessed in relation to two different types of forest harvesting practices: whole-tree harvesting; and stem harvesting. The results demonstrate that local emission reductions combined with tree stem harvesting give the greatest remediation of soil acidity. This implies that forest soil acidity can be introduced as an indicator in local environmental planning.  相似文献   

7.
目前国内关于海洋修复工程的考核研究多为修复工程的生态效果考核,极少包含成本效益考核,以致无法比较和分析不同类型、不同规模的海洋修复工程的生态绩效,不利于海洋修复工程的考核和验收管理。根据当前自然资源部实施“蓝色海湾”等整治修复工程的检查验收管理的新需求,本文构建了基于海洋生态系统健康恢复、生态系统服务价值增长和单位成本生态效益等理论的海洋修复工程生态绩效考核指标体系。此外,本文以温州海域2014—2016年海洋修复的生态绩效的考核为例,结合考核结果以及直接相关性、独立性、可测量性和业务化等指标选取原则,对指标体系进行了改进。结果表明本指标体系可以在海洋修复工程的检查验收中被用于生态绩效考核,管理部门可根据海洋修复工程的类型和管理需求,有选择性地采纳部分或全部指标进行考核。  相似文献   

8.
ABSTRACT: The objective of this study was to evaluate the effectiveness of various land-use practices upon the production of nonpoint source pollutants from small agricultural watersheds in Northern Virginia. Pollutant production at each watershed was determined by individual monitoring stations. Data analysis consisted of a determination of the site specific pollutant yield for similar watersheds subjected to differing crop management approaches. These collected data were then compared to those generated by a parametric, event model developed for this investigation. This synthetic data base was used to eliminate or reduce errors resulting from monitoring site differences and to extend the collected data for additional comparisons.  相似文献   

9.
When designing energy efficient buildings it is useful to study existing climate—responsive building typologies. The wind towers or wind-catchers of Yazd city in Iran are typical examples of such a typology. Although many previous studies have investigated the performance of various types of wind catcher systems, studies based on a long-term real-life measurement can be rarely found. In this study a long-term whole year monitoring campaign on an existing full scale four sided wind catcher in Yazd was carried out in 2014–2015. Three prevailing wind directions were identified and the measured on-site wind speeds were used to estimate the wind induced natural ventilation potential of the tower. A shaft/tower airflow performance index was developed. The monitoring results were compared to the ASHRAE Standard 62:2001 ventilation rate requirement. Results show that the total ventilation rate of the wind tower surpasses the ASHRAE Standard requirements. Furthermore it shows that the shafts are exposed to the prevailing wind directions perform better. For more effective natural ventilation a wind tower with adaptable openings/shafts are proposed.  相似文献   

10.
Abstract: Consistency in determining Rosgen stream types was evaluated in 12 streams within the John Day Basin, northeastern Oregon. The Rosgen classification system is commonly used in the western United States and is based on the measurement of five stream attributes: entrenchment ratio, width‐to‐depth ratio, sinuosity, slope, and substrate size. Streams were classified from measurements made by three monitoring groups, with each group fielding multiple crews that conducted two to three independent surveys of each stream. In only four streams (33%) did measurements from all crews in all monitoring groups yield the same stream type. Most differences found among field crews and monitoring groups could be attributed to differences in estimates of the entrenchment ratio. Differences in entrenchment ratio were likely due to small discrepancies in determination of maximum bankfull depth, leading to potentially large differences in determination of Rosgen’s flood‐prone width and consequent values of entrenchment. The result was considerable measurement variability among crews within a monitoring group, and because entrenchment ratio is the first discriminator in the Rosgen classification, differences in the assessment of this value often resulted in different determination of primary stream types. In contrast, we found that consistently evaluated attributes, such as channel slope, rarely resulted in any differences in classification. We also found that the Rosgen method can yield nonunique solutions (multiple channel types), with no clear guidance for resolving these situations, and we found that some assigned stream types did not match the appearance of the evaluated stream. Based on these observations we caution the use of Rosgen stream classes for communicating conditions of a single stream or as strata when analyzing many streams due to the reliance of the Rosgen approach on bankfull estimates which are inherently uncertain.  相似文献   

11.
The purpose of this study was to collect specific information on the characteristics and intensity of local Blue Ridge Parkway use and to use that information to develop a recreation use model of local Parkway visitation. Data were obtained from a self-administered mail-back questionnaire sent to a random sample of people living in the 29 counties adjacent to the Parkway.We developed two recreation use projection/demand models that employ three variables (distance, alternative recreation sites, and population density) to predict visitation to different Parkway areas from various local origins. The derived model estimates indicated that about one-fourth of all Parkway visits in 1978 were one-day visits made by area residents.  相似文献   

12.
As the number of marine protected areas (MPAs) is globally increasing, information is needed on the effectiveness of existing sites. Many protected area agencies however have limited resources and are unable to evaluate MPA effectiveness. An evaluation conducted entirely by the managing agency may also lack credibility. Long-term monitoring and evaluation programs should ideally offer opportunities for participation of diverse groups in the selection of evaluation indicators and their assessment. A participatory approach has the potential to enhance evaluation capacity, to increase credibility and acceptance of results, to strengthen relationships between managers and local stakeholders, and to address more locally relevant information. Using a case study approach, this paper investigates diverse stakeholder groups’ opinions on the design of an evaluation and their interest to participate in an assessment. Respondents were most interested in the assessment of MPA achievements and outcome indicators. Most groups identified a range of government agencies and stakeholders that should participate in an assessment but only half of all respondents were interested to participate in monitoring activities. Most frequently mentioned limitations for more participation were a lack of time and money, but also governance shortcomings such as limited participation possibilities and not paying enough credit to stakeholders’ input. Participation interest was also influenced by occupation, place of residency, and familiarity with the marine environment. Differences exist among stakeholders about suitable evaluators and preferred monitoring partners, which could affect the credibility of evaluation results and affect monitoring activities.  相似文献   

13.
This article summarizes a research project that investigated the use, performance, cost, and evaluation of nonstructural measures to improve urban stormwater quality. A survey of urban stormwater managers from Australia, New Zealand, and the United States revealed a widespread trend of increasing use of nonstructural measures among leading stormwater management agencies, with at least 76% of 41 types of nonstructural measures being found to be increasing in use. Data gathered from the survey, an international literature review, and a multicriteria analysis highlighted four nonstructural measures of greatest potential value: mandatory town planning controls that promote the adoption of low-impact development principles and techniques; development of strategic urban stormwater management plans for a city, shire, or catchment; stormwater management measures and programs for construction/building sites; and stormwater management activities related to municipal maintenance operations such as maintenance of the stormwater drainage network and manual litter collections. Knowledge gained on the use and performance of nonstructural measures from the survey, literature review, and three trial evaluation projects was used to develop tailored monitoring and evaluation guidelines for these types of measure. These guidelines incorporate a new evaluation framework based on seven alternative styles of evaluation that range from simply monitoring whether a nonstructural measure has been fully implemented to monitoring its impact on waterway health. This research helps to build the stormwater management industry’s knowledge base concerning nonstructural measures and provides a practical tool to address common impediments associated with monitoring and evaluating the performance and cost of these measures.  相似文献   

14.
The condenser is a piece of equipment used to effectively transfer heat from water to the environment. The fin and tube condenser is the most commonly used in commercial applications. The improved performance of heat transfer in the fin and tube condenser is a significant area of study all over the world because optimizing the efficiency of heat transfer in the condenser will contribute to enhancing the effectiveness of system performance. The vapor deposition, plasma spray, and thermal spray techniques are being used, and it is determined that a heat transfer enhancing coating improves condenser performance. This review discusses the nanomaterial coating over the fin and tube condenser in detail. The various nanomaterial coatings with various propositions and coating methods had been discussed with the evidence of previous researchers. At a 50-degree inclination angle on the condensate plate, the condensate over the coating surface increases by more than 30%. The thermal properties of the working fluid are improved over the condenser, and the overall effectiveness of the condenser is increased by approximately 40% over the non-coated condenser. A 1% volumetric concentration of Nanoparticles in the coated material achieves a maximum efficiency increase of 78.7%.  相似文献   

15.
Optical and chemical aerosol measurements were obtained from 2 to 31 July 2006 at an urban site in the metropolitan area of Guangzhou (China) as part of the Program of Regional Integrated Experiment of Air Quality over Pearl River Delta (PRIDE-PRD2006) to investigate aerosol chemistry and the effect of aerosol water content on visibility impairment and radiative forcing. During the PRIDE-PRD2006 campaign, the average contributions of ammonium sulfate, organic mass by carbon (OMC), elemental carbon (EC), and sea salt (SS) to total PM2.5 mass were measured to be 36.5%, 5.7%, 27.1%, 7.8%, and 3.7%, respectively. Compared with the clean marine period, (NH4)2SO4, NH4NO3, and OMC were all greatly enhanced (by up to 430%) during local haze periods via the accumulation of a secondary aerosol component. The OMC dominance increased when high levels of biomass burning influenced the measurement site while (NH4)2SO4 and OMC did when both biomass burning and industrial emissions influenced it. The effect of aerosol water content on the total light-extinction coefficient was estimated to be 34.2%, of which 25.8% was due to aerosol water in (NH4)2SO4, 5.1% that in NH4NO3, and 3.3% that in SS. The average mass-scattering efficiency (MSE) of PM10 particles was determined to be 2.2 ± 0.6 and 4.6 ± 1.7 m2 g−1 under dry (RH < 40%) and ambient conditions, respectively. The average single-scattering albedo (SSA) was 0.80 ± 0.08 and 0.90 ± 0.04 under dry and ambient conditions, respectively. Not only are the extinction and scattering coefficients greatly enhanced by aerosol water content, but MSE and SSA are also highly sensitive. It can be concluded that sulfate and carbonaceous aerosol, as well as aerosol water content, play important roles in the processes that determine visibility impairment and radiative forcing in the ambient atmosphere of the Guangzhou urban area.  相似文献   

16.
Post-Project Appraisals in Adaptive Management of River Channel Restoration   总被引:5,自引:3,他引:2  
Post-project appraisals (PPAs) can evaluate river restoration schemes in relation to their compliance with design, their short-term performance attainment, and their longer-term geomorphological compatibility with the catchment hydrology and sediment transport processes. PPAs provide the basis for communicating the results of one restoration scheme to another, thereby improving future restoration designs. They also supply essential performance feedback needed for adaptive management, in which management actions are treated as experiments. PPAs allow river restoration success to be defined both in terms of the scheme attaining its performance objectives and in providing a significant learning experience. Different levels of investment in PPA, in terms of pre-project data and follow-up information, bring with them different degrees of understanding and thus different abilities to gauge both types of success. We present four case studies to illustrate how the commitment to PPA has determined the understanding achieved in each case. In Moore's Gulch (California, USA), understanding was severely constrained by the lack of pre-project data and post-implementation monitoring. Pre-project data existed for the Kitswell Brook (Hertfordshire, UK), but the monitoring consisted only of one site visit and thus the understanding achieved is related primarily to design compliance issues. The monitoring undertaken for Deep Run (Maryland, USA) and the River Idle (Nottinghamshire, UK) enabled some understanding of the short-term performance of each scheme. The transferable understanding gained from each case study is used to develop an illustrative five-fold classification of geomorphological PPAs (full, medium-term, short-term, one-shot, and remains) according to their potential as learning experiences. The learning experience is central to adaptive management but rarely articulated in the literature. Here, we gauge the potential via superimposition onto a previous schematic representation of the adaptive management process by Haney and Power (1996). Using PPAs wisely can lead to cutting-edge, complex solutions to river restoration challenges.  相似文献   

17.
ABSTRACT: The salinity of the lower South Platte River in Colorado is characterized by plotting the average annual flow, total dissolved solids, and salt mass flow against distance along the stream. The plots show that salts are being leached from the irrigated lands above Greeley and are being deposited on the irrigated lands below Greeley. The salt deposition on the lower lands will result in their salination. The plots show also that fall and winter stream flows carry most of the salt loads. These fall and winter flows are stored in off stream reservoirs for use during the irrigation season. Therefore these salts are transferred to the lower irrigated lands where they accumulate. The salt balance for these lands can be improved by permitting the fall and winter flows to leave the basin, or by providing adequate land drainage coupled with supplemental irrigation water.  相似文献   

18.
Sustainable management of landscapes with multiple competing demands such as the Ruaha Landscape is complex due to the diverse preferences and needs of stakeholder groups involved. This study uses conjoint analysis to assess the preferences of representatives from three stakeholder groups—local communities, district government officials, and non-governmental organizations—toward potential solutions of conservation and development tradeoffs facing local communities in the Ruaha Landscape of Tanzania. Results demonstrate that there is little consensus among stakeholders about the best development strategies for the Ruaha region. This analysis suggests a need for incorporating issues deemed important by these various groups into a development strategy that aims to promote conservation of the Ruaha Landscape and improve the livelihood of local communities.  相似文献   

19.
The management of the big amount of fly ash as hazardous waste from the municipal solid waste incinerator (MSWI) has encountered many problems in China. In this study, a feasibility research on MSWI fly ash utilization as partial cement substitute in cement mortars was therefore carried out. MSWI fly ash was subjected to washing process to reduce its chlorine content (from 10.16% to 1.28%). Consequently, it was used in cement mortars. Ten percent and 20% replacement of cement by washed ash showed acceptable strength properties. In TCLP and 180-day monolithic tests, the mortars with washed ash presented a little stronger heavy metal leachability, but this fell to the blank level (mortar without washed ash) with the addition of 0.25% chelate. Therefore, this method is proposed as an environment-friendly technology to achieve a satisfactory solution for MSWI fly ash management.  相似文献   

20.
Typical tasks of a river monitoring network design include the selection of the water quality parameters, selection of sampling and measurement methods for these parameters, identification of the locations of sampling stations and determination of the sampling frequencies. These primary design considerations may require a variety of objectives, constraints and solutions. In this study we focus on the optimal river water quality monitoring network design aspect of the overall monitoring program and propose a novel methodology for the analysis of this problem. In the proposed analysis, the locations of sampling sites are determined such that the contaminant detection time is minimized for the river network while achieving maximum reliability for the monitoring system performance. Altamaha river system in the State of Georgia, USA is chosen as an example to demonstrate the proposed methodology. The results show that the proposed model can be effectively used for the optimal design of monitoring networks in river systems.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号