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1.
Climate change has significant impacts on biodiversity and, particularly, on agriculture. In this study, the impact of climate change on five varietal groups of Sechium edule, up to the year 2050, was determined through the application of the HadGEM2-CC model based on bioclimate layers. The varietal groups, nigrum minor, albus dulcis and nigrum xalapensis, will lose more than 50 % of their potential current distribution due to a high impact in both the rcp 45 and the rcp 85 scenarios. These two varietal groups also have a limited distribution, which makes them highly susceptible. In the case of nigrum spinosum, a loss under 50 % is predicted with scenario rcp 45. The varietal group that increases its distribution in 11 % is virens levis. The model forecasts significant impacts up to the year 2050; however, the groups evaluated present high genetic diversity and phenotypic plasticity which allow adapting to new conditions that may contribute to mitigating the effects of climate change.  相似文献   

2.
Shah  Jitendra J.  Nagpal  Tanvi  Johnson  Todd  Li  Jia  Peng  C. 《Water, air, and soil pollution》2001,130(1-4):235-240
China's continuing dependence on coal suggests a need for a cost-effective strategy to address SO2 and acid rain impacts. Results of modeling studies show that although there are important transboundary aspects of acid rain in Asia, the majority of emissions and damages lie within China. This implies that intra-regional cooperation within China, and cost-effective sulfur control are paramount for limiting acid rain damages. This article discusses the costs and benefits of six primary and secondary control and policy options using the RAINS-ASIA and UR-BAT models. The local health benefits were estimated to be an order of magnitude larger than the ecosystem benefits at the regional level. All abatement options involve substantial costs, except intensive energy efficiency which is the most cost effective with the rate of return of almost 200 per dollar as compared to around 6 for the other options.  相似文献   

3.
Sensitivity analysis is important for determining the parameters in the model calibration process. In our study, a variance-based global sensitivity analysis (extended Fourier amplitude sensitivity test, EFAST) was applied to an agro-hydrological model (the SWAP (Soil-Water-Atmosphere-Plant model) model). The sensitivities of 20 parameters belonging to 4 categories (soil hydraulics, solute transport, root water uptake, and environmental stresses) for the simulated accumulated transpiration, dry matter (DM), and yield of sunflowers were analyzed under three nitrogen application rates (N1, N2, and N3), four salinity levels (S1, S2, S3, and S4), and three root distributions (R1, R2, and R3). The results indicated that for predominantly loamy soils, the high-impact parameters for accumulated transpiration, DM, and yield were the soil hydraulic parameters (α and n), critical stress index for compensatory root water uptake (ωc), the salt level at which salt stress starts (Pi), the decline of root water uptake above Pi (SSF), residual water content (θr), saturated water content (θs), and relative uptake of solutes by roots (TSCF). We also found that nitrogen application did not change the order of the parameter impacts on accumulated transpiration, DM, and yield. However, TSCF replaced α as the highest-impact parameter for the accumulated transpiration, DM, and yield at high salinity levels (S2 and S3). Furthermore, α was also the highest-impact parameter for DM and yield under different root distributions, but the highest-impact parameters for transpiration were ωc, α, and θs under R1, R2, and R3, respectively. Nitrogen application could be neglected when considering the interactive effects of nitrogen application, salinity level, and root distribution on the transpiration, DM, and yield. Additionally, the mean values and uncertainties of the transpiration, DM, and yield were similar in all scenarios, except S3, which showed a sharp decrease in the mean values. We suggest determining the above eight parameters (α, n, ωc, Pi, SSF, θr, θs, and TSCF) and the saturated vertical hydraulic conductivity (Ks) based on rigorous calibrations with direct or indirect local measurements using economical methods (e.g., a literature review), with limited observations for other parameters when using the SWAP model and other similar agro-hydrological models.  相似文献   

4.
Identifying good investments in environmental management is complex as several prioritization strategies may be used and significant uncertainty often surrounds cost, benefits, and agency budgets. In this paper I developed a model for robust portfolio selection based on preference programming to support cost-effective environmental investment decisions under uncertainty and applied it to the South Australian Murray-Darling Basin. Benefits and costs of 46 investment alternatives (called targets) for managing natural capital and ecosystem services were quantified and the associated uncertainty estimated. Thirty-six investment portfolios were selected using mathematical programming under four investment prioritization strategies (cost-effectiveness (E-max), cost-effectiveness including a suite of pre-committed (or core) costs (E-max∗), cost-only (C-rank), and benefit-only (B-rank)), three decision rules (pessimistic, most likely, and optimistic), and three budget scenarios (minimum, most likely, maximum). Compared to the optimally performing investment strategy E-max, the E-max∗ and C-rank strategies only slightly reduced portfolio performance and altered portfolio composition. However, the B-rank strategy reduced performance by half and radically changed composition. Uncertainty in costs, benefits, and available budgets also strongly influenced portfolio performance and composition. I conclude that in this case study the consideration of uncertainty was at least as important as investment strategy in effective environmental decision-making. Targets whose selection was less sensitive to uncertainty were identified as more robust investments. The results have informed the allocation of AU$69 million in the study area and the techniques are readily adaptable to similar conservation and environmental investment decisions in other areas at a variety of scales.  相似文献   

5.
Acidifying emissions from energy production and industry have decreased considerably during the last two decades in Finland. Especially the emissions of sulphur dioxide have dropped sharply with 85% in 1980–1998, although the energy use has increased 30% during the same period. The reduction has occurred through two mechanisms: by replacing the combustion of heavy fuel oil with cleaner energy carriers, and by direct emission reduction controls, e.g. flue gas desulphurization. In this study the Finnish cost curves for SO2 and NOx were first calculated to produce a consistent comprehensive view on further emission reduction costs and potentials. The data on technical and cost-related parameters were based on actual national experiences from power plants and industry. Most of the cost-efficient sulphur emission controls were already in use. For NOx, a large share of further reduction potential still remained. Second, a case on the emission reductions and costs for fuel switching in a 205 MWth peat power plant of Tampere Power Utility in Finland was studied. Fuel switching to natural gas was found less cost-efficient in SO2 and NOx emission reduction when compared to flue gas cleaning techniques. The findings provided new information on fuel switching as an alternative potential reduction measure, which is not considered in international assessments.  相似文献   

6.
For the January 1985 smog episode concentrations of SO2, sulphate (SO4), NO x (sum of NO and NO2) and nitrate (NO3) have been calculated for north-western Europe by means of an atmospheric transport model. The unfavorable dispersion conditions (moderate to low wind speeds, a low mixing height and a strong inversion) and a reduced dry deposition over the snow-covered or frozen soil, in combination with increased space heating emissions due to the exceptionally cold weather, gave rise to high ground level concentrations. In order to study the effectiveness of control measures during this type of episodes, calculations were made for various emission scenarios. The results were evaluated for four receptor areas, two areas relatively close to the major sources (The Netherlands and the Black Forest) and two more remote areas (Scotland and the SW coast of Sweden, near Gothenburg).  相似文献   

7.
Crop production in Georgia and the Southeastern U.S. can be limited by water. Highly-weathered, drought-prone soils are susceptible to runoff and erosion. Rainfall patterns generate runoff producing storms followed by extended periods of drought during the crop growing season. Thus, supplemental irrigation is often needed to sustain profitable crop production. Increased water retention and soil conservation would efficiently improve water use and reduce irrigation amounts/costs and sedimentation, and sustain productive farm land, thus improving producer's profit margin. Soil amendments, such as flue gas desulfurization (FGD) gypsum, have been shown to retain rainfall and/or irrigation water through increased infiltration while decreasing runoff (R) and sediment (E). Objectives were to quantify rainfall partitioning and sediment delivery improvements with surface applied FGD gypsum from an Ultisol managed to conventional till (CT) and to assess the feasibility of using FGD gypsum on agricultural land in southern Georgia. A field study (Faceville loamy sand, Typic Kandiudult) was established (2006, 2007) near Dawson, GA managed to CT, irrigated cotton (Gossypium hirsutum L.). FGD gypsum application rates evaluated were 0, 1.1, 2.2, 4.5, and 9 Mg ha− 1. Gypsum treatments and simulated rainfall (50 mm h− 1 for 1 h) were applied to 2-m wide × 3-m long field plots (n = 3). Runoff and E were measured from each 6-m2 plot (slope = 1%). FGD gypsum plots averaged 26% more infiltration (INF), 40% less R, 58% less E, 27% lower maximum R rates (Rmax), and 2 times lower maximum E rates (Emax) than control plots. Values of INF and water for crop use increased, and R, E, Rmax, and Emax decreased as FGD gypsum application rate increased. Values of INF, R, E, Rmax, and Emax for 9 Mg ha− 1 plots were as much as 17% greater, 35% less, 1.9 times less, 35% less, and 1.9 times less than those from other FGD gypsum plots, respectively; and 40% greater, 40% less, 2.2 times less, 52% less, and 2.9 times less than those from control plots, respectively. Applying FGD gypsum to agricultural lands is a cost-effective management practice for producers in Georgia that beneficially impacts natural resource conservation, producer profit margins, and environmental quality. Agriculture in the Southeast provides a viable market for the electric power industry to convert disposal costs of FGD gypsum into a profitable commodity.  相似文献   

8.
不同土地利用变化情景下的洪汝河流域水文响应   总被引：1，自引：0，他引：1  
[目的]研究洪汝河流域土地利用变化对水文过程的影响,为当地水资源的合理规划和利用提供依据和参考。[方法]本研究以土壤水体评价模型(soil and water assessment tool,SWAT)为基础,通过设计多种土地利用情景模式模拟洪汝河流域水文情景,首先利用数字高程模型(digital elevation model,DEM),土地利用数据、土壤数据以及日气象数据建立模型;其次选用2006—2008年的水文观测数据进行模型率定,并进行敏感性和不确定性分析;最后,设置4种土地利用情景模式进行水文模拟。[结果]退耕还林情景下径流减少4.23%;而在耕地增加,城镇用地增加和以城镇用地、林地草地增加为主的复杂土地利用变化这3种情景下,径流分别增加3.01%,4.91%和1.50%。[结论]退耕还林增加了可涵养水源的森林,使得径流减少,而增加耕地开垦或城市建设用地则会增加地表径流。  相似文献   

9.
Abstract

The scenarios for conventional puddling and no-tilling rice (Oryza sativa L.) cultivation were compared in terms of greenhouse gas (GHG) emissions from paddy fields, fuel consumption and manufacturing of invested materials using a life cycle inventory (LCI) based analysis. Only the differences between the scenarios were examined. The no-tilling scenario omitted both tilling and puddling, but included spraying of a non-selective herbicide and used a transplanter equipped with a rotor. Fertilization was a basal single application of controlled release fertilizer in nursery boxes for all scenarios. After transplanting, there were no differences in machine work, invested materials or rice yields between the scenarios. The no-tilling scenario saved on fuel consumption, totaling carbon dioxide (CO2) output of 42 kg ha?1, which was equal to the 6% reported GHG emissions from fuel consumption by operating machines during rice production in Japan. Methane (CH4) and nitrous oxide (N2O) emissions from the paddy fields were also monitored and compared for the scenarios. Methane has a major effect on global warming as part of the GHG emitted from paddy fields. The cumulative CH4 emissions from the no-tilling cultivation were 43% lower than those from conventional puddling cultivation because the plow layer was more oxidative in no-tilling cultivation. The N2O emissions were not significantly different between the cultivation scenarios. There were no significant differences in soil respiration, soil carbon contents or straw yields between the cultivation scenarios. The effect of tillage on CO2 flux in the paddy fields did not seem to be significant in this study. Consequently, the GHG emissions from the no-tilling field counted as CO2 using global warming potentials were 1,741 kg CO2 ha?1 lower than those from the conventional puddling field. In conclusion, no-tilling rice cultivation has the potential to save 1,783 kg CO2 ha?1 calculated using the sum of fuel consumption and GHG emissions from paddy fields. No-tilling rice cultivation is considered to be environmentally friendly agriculture with respect to reducing GHG emissions.  相似文献   

10.
Understanding the responses of soil C mineralization to climate change is critical for evaluating soil C cycling in future climatic scenarios. Here, we took advantage of a multifactor experiment to investigate the individual and combined effects of experimental warming and increased precipitation on soil C mineralization and 13C and 15N natural abundances at two soil depths (0–10 and 10–20?cm) in a semiarid Inner Mongolian grassland since April 2005. For each soil sample, we calculated potentially mineralizable organic C (C 0) from cumulative CO2-C evolved as indicators for labile organic C. The experimental warming significantly decreased soil C mineralization and C 0 at the 10–20-cm depth (P?<?0.05). Increased precipitation, however, significantly increased soil pH, NO 3 ? -N content, soil C mineralization, and C 0 at the 0–10-cm depth and moisture and NO 3 ? -N content at the 10–20-cm depth (all P?<?0.05), while significantly decreased exchangeable NH 4 + -N content and 13C natural abundances at the two depths (both P?<?0.05). There were significant warming and increased precipitation interactions on soil C mineralization and C 0, indicating that multifactor interactions should be taken into account in future climatic scenarios. Significantly negative correlations were found between soil C mineralization, C 0, and 13C natural abundances across the treatments (both P?<?0.05), implying more plant-derived C input into the soils under increased precipitation. Overall, our results showed that experimental warming and increased precipitation exerted different influences on soil C mineralization, which may have significant implications for C cycling in response to climate change in semiarid and arid regions.  相似文献   

11.
The decision to release a new transgenic crop variety for planting in the European Union (EU) is a decision under irreversibility and uncertainty. We use a real option model to assess the ex-ante incremental benefits and costs of the decision to release Bt maize and HT maize in the EU-15 member states. The analysis uses Eurostat data for modelling the benefits and costs of non-transgenic maize using partial equilibrium models. The farm-level benefits and costs of Bt maize and HT maize are derived from field trials conducted within the EU-funded ECOGEN project in combination with secondary data sources. Adoption curves, hurdle rates and Maximum Incremental Social Tolerable Irreversible Costs (MISTICs) are calculated at country level for selected EU-15 member states. In general, the results show that the MISTICs on a per capita level are very small confirming previous results calculated in values for the year 1995. The MISTICs per farm are much larger. This indicates a problem for decision makers.  相似文献   

12.
Ant mounds often occur at high densities in marsh wetlands. However, little information is available regarding their impacts on soil nutrient pools in these ecosystems. We studied Corg, dissolved organic carbon (DOC), total nitrogen (TN), NO3− and NH4+ concentrations in above-ground ant mounds and in soils under mounds for three ant species (Lasius flavus, Lasius niger and Formica candida), and estimated their contribution to the total soil nutrient pools in a marsh wetland. Ant impacts were greatest in above-ground soils. All measured nutrient concentrations in above-ground mounds were significantly higher than the average values in reference soils (upper 25 cm). However, except for DOC, no significant differences for nutrient concentrations existed between soils under mounds and reference soils. The impacts of ant mounds on soil C and nutrient concentrations varied by ant species. L. niger above-ground mounds stored less Corg, TN and NO3− than F. candida and L. flavus mounds, or reference soils. At the ecosystem scale, soils in above-ground mounds and under ant mounds all contained less Corg per hectare than the reference soils. Total amounts in nutrient pools from mounds of the three ant species comprised from 5.3% to 7.6% of the total in natural marsh soils. More importantly, ant mounds increased the spatial heterogeneity of nutrient pools. Thus, ant mounds can be important to a fully integrated understanding of the structure and function of wetland nutrient cycles and balances.  相似文献   

13.
《Applied soil ecology》2011,48(3):160-166
We studied the effect of water table on CO2 and CH4 fluxes at different time scales in the littoral zone of Lake Obuchi, a brackish lake in northern Japan. The vegetation formed three distinct zones along the water table gradient, two dominated by emergent aquatic macrophytes (the Phragmites australis-dominated zone and the Juncus yokoscensis-dominated zone) and one dominated by terrestrial macrophytes (Miscanthus sinensis and Cirsium inundatum-dominated zone). To clarify the impact of variations in water table on monthly and yearly summed CO2 and CH4 fluxes, we examined the relationship between water table and the ratio of observed flux to calculated flux, whereby the calculated flux was based solely on the exponential relationship between flux and soil temperature for each gas. This study revealed that the impact of variations in water table on monthly and yearly summed CO2 and CH4 fluxes differed markedly between the vegetation zones. By taking the temporal change in water table into account in the estimation of both the CO2 and CH4 fluxes, the monthly summed CO2 and CH4 fluxes in the Phragmites-zone were markedly greater in every month of the year compared to estimation based on temperature alone. In the Juncus-zone, the effect of water table on monthly summed CO2 and CH4 fluxes differed between months. In addition, the magnitude of water-table effects controlling monthly summed CO2 and CH4 fluxes differed with atmospheric conditions, i.e., between the pressure-falling and low-pressure phase on the one hand and other pressure phases on the other hand. After weighting all the impacts of temporal changes in water table on fluxes, the yearly summed CO2 and CH4 fluxes showed a 1.26–6.64-fold increase compared with not taking water table effects into account, and the increase differed among the three vegetation zones.  相似文献   

14.
Different approaches have been proposed for quantification of soil water availability for plants but mostly they do not fully describe how water is released from the soil to be absorbed by the plant roots. A new concept of integral energy (EI) was suggested by Minasny and McBratney (Minasny, B., McBratney, A.B. 2003. Integral energy as a measure of soil-water availability. Plant and Soil 249, 253-262) to quantify the energy required for plants to take up a unit mass of soil water over a defined water content range. This study was conducted to explore the EI concept in association with other new approaches for soil water availability including the least limiting water range (LLWR) and the integral water capacity (IWC) besides conventional plant available water (PAW). We also examined the relationship between EI and Dexter's index of soil physical quality (S-value). Twelve agricultural soils were selected from different regions in Hamadan province, western Iran. Soil water retention and penetration resistance, Q, were measured on undisturbed samples taken from the 5-10 cm layer. The PAW, LLWR and IWC were calculated with two matric suctions (h) of 100 and 330 hPa for field capacity (FC), and then the EI values were calculated for PAW, LLWR and IWC. There were significant differences (P < 0.01) between the EI values calculated for PAW100, PAW330, LLWR100, LLWR330 and IWC. The highest (319.0 J kg−1) and the lowest (160.7 J kg−1) means of EI were found for the EI(IWC) and EI(PAW330), respectively. The EI values calculated for PAW100, LLWR100 and LLWR330 were 225.6, 177.9 and 254.1 J kg−1, respectively. The mean value of EI(PAW330) was almost twice as large as the mean of EI(IWC) showing that IWC is mostly located at lower h values when compared with PAW330. Significant relationships were obtained between EI(IWC) and h at Q = 1.5 MPa, and EI(LLWR100) or EI(LLWR330) and h at Q = 2 MPa indicating strong dependency of EI on soil strength in the dry range. We did not find significant relationships between EI(PAW100) or EI(PAW330) and bulk density (ρb) or relative ρb (ρb-rel). However, EI(LLWR100) or EI(LLWR330) was negatively and significantly affected by ρb and ρb-rel. Both EI(PAW100) and EI(PAW330) increased with increasing clay content showing that a plant must use more energy to absorb a unit mass of PAW from a clay soil than from a sandy soil. High negative correlations were found between EI(PAW100) or EI(PAW330) and the shape parameter (n) of the van Genuchten function showing that soils with steep water retention curves (coarse-textured or well-structured) will have lower EI(PAW). Negative and significant relations between EI(PAW100) or EI(PAW330) and S were obtained showing the possibility of using S to predict the energy that must be used by plants to take up a unit mass of water in the PAW range. Our findings show that EI can be used as an index of soil physical quality in addition to the PAW, LLWR, IWC and S approaches.  相似文献   

15.
An eulerian long-range transport model for the calculation of concentrations of SO2, SO4, NO x , and NO3 and wet and dry depositions of SO x (sum of SO2 and SO4) and NO y (sum of NO, NO2 and NO3) over Europe is presented. The model is developed in such a way that only routinely available, analyzed or prognostic meteorological fields are required as input data. In this way it is possible to obtain a forecast of the air quality during smog episodes. For evaluation of smog episodes the model provides a way to estimate the contributions of different sources and the effect of emission scenarios. The model has been evaluated for four winter and three summer episodes. The modeled concentrations of SO2 and SO, are in agreement with the available measurements. A less good agreement is found for NO2 and NO x (sum of NO and NO2) concentrations. For these components the model tends to underpredict the measured values.  相似文献   

16.
The International Cooperative Programme on Integrated Monitoring (ICP IM) is part of the effects monitoring strategy of the UN/ECE Convention on Long-Range Transboundary Air Pollution. We calculated input-output budgets and trends of N and S compounds, base cations and hydrogen ions for 22 forested ICP IM catchments/plots across Europe. The site-specific trends were calculated for deposition and runoff water fluxes and concentrations using monthly data and non-parametric methods. The reduction in deposition of S and N compounds, caused by the new Gothenburg Protocol of the Convention, was estimated for the year 2010 using atmospheric transfer matrices and official emissions. Statistically significant downward trends of SO4, NO3 and NH4 bulk deposition (fluxes or concentrations) were observed at 50% of the ICP IM sites. Implementation of the new UN/ECE emission reduction protocol will further decrease the deposition of S and N at the ICP IM sites in western and northwestern parts of Europe. Sites with higher N deposition and lower C/N-ratios clearly showed an increased risk of elevated N leaching. Decreasing SO4 and base cation trends in output fluxes and/or concentrations of surface/soil water were commonly observed at the ICP IM sites. At several sites in Nordic countries decreasing NO3 and H+ trends (increasing pH) were also observed. These results partly confirm the effective implementation of emission reduction policy in Europe. However, clear responses were not observed at all sites, showing that recovery at many sensitive sites can be slow and that the response at individual sites may vary greatly.  相似文献   

17.
To prioritize conservation actions on Italian islands we used the case study of the eradication of the Black rat Rattus rattus to protect Cory’s shearwater Calonectris diomedea and Yelkouan shearwater Puffinus yelkouan. We evaluated for each island the effectiveness of rat eradication by means of two different indices, both based on the relative importance of the island’s nesting population of the two species at the national and regional scale, but differing in the parameters set at the divisor, i.e., respectively, the number of nesting pairs in rat-free islands and the number of islands occupied by shearwaters. We estimated analytically the monetary costs of rat eradication on each island. Islands at high risk of recolonization were excluded from further analyses, while costs and effectiveness of rat eradication were compared for the remaining islands. Rat eradication was most cost-effectively carried out on the island hosting the largest colony of P. yelkouan. Eradicating rats from all the islands in the ranking provided benefits to 63.9% of the Italian population of P. yelkouan, but only to 7.1% of that of C. diomedea. Comparing costs and effectiveness of all possible island combinations, ranging from a minimum budget of 50,000 € and a maximum of 1600,000 € (i.e. the cost for eradicating rats from all the listed islands), the maximum increase in effectiveness (marginal effectiveness) fell around a relatively small budget (200,000 €). For both species, when adopting the cost/effectiveness rankings, the number of pairs protected for 1000 € of investment was significantly higher than adopting rankings of effectiveness alone, demonstrating that conservation priorities are more efficiently identified by including monetary costs in the analysis.  相似文献   

18.
The research presented here represents a segment of a cumulative impact assessment of resource development in northeastern British Columbia. It considers point and area source emissions of sulphur and nitrogen oxides (SO2 and NO x , respectively), over a 2,156-km2 area. With the exception of open burning, all emissions are from Upstream Oil and Gas (UOG) sector sources (SO2, n?=?103; NO x , n?=?250; area, n?=?25). AERMOD View? was used to estimate the maximum potential concentration and deposition of these pollutants over 1-h, 3-h, 24-h, and annual averaging periods. Results are compared with various thresholds and limits from the policy and scientific literature to assess the potential cumulative effects of these pollutants. Of the thresholds employed, exceedances of the 1-h and 24-h NO x concentrations and the annual SO2 concentration are predicted. There were no predicted exceedances of annual deposition thresholds (i.e., ??Critical Loads??). Maximum predicted concentrations vary between compounds and are related to boundary layer stability, elevation, and distance from sources. Comparison with nearby monitoring data indicated that predicted concentrations were reasonable and that AERMOD provides a useful tool for approaching the potential cumulative impacts of air pollution from multiple sources. While the accuracy of Gaussian-based annual deposition estimates is questioned, model enhancements that could extend the application to more comprehensive assessments are suggested. Lastly, the implications of predicted threshold violations for forest ecosystems and local forest-dependent First Nations communities are discussed.  相似文献   

19.
Increases in N deposition (wet and dry) have been associated with a decline in semi-natural plant communities, adapted for growth on nutrient poor soils in the UK and Europe. The impacts of N deposition applied as either wet NH4 + or gaseous NH3 on vegetation (7 species) from acid moorland in SE Scotland were compared in a dose-response study. Wet N deposition at 0, 8, 16, 32, 64, 128 kg N ha?1 y?1 was applied as NH4Cl, and dry deposition as gaseous NH3 (2, 6, 20, 50, 90 µg NH3 m?3) under controlled conditions in open-top chambers. A strong linear dose-response relationship (p<0.05) was found between foliar N content in all seven plant species and applied NH4?N. However, in the NH3 treatment, only C. vulgaris and P. commune showed a significant response to increasing N additions. NH3 was found to increase the rate of water loss in Calluna in both autumn and winter by comparison with wet deposition. For Eriophorum vaginatum, the NH3 and NH4 + treatments showed significant N dose response relationships for biomass. A significant increase in above ground biomass, proportional to the added N, was found for Narthecium ossifragum when N was applied as NH3 compared to NH4 +.  相似文献   

20.
Cost-benefit analysis is one of the fundamental tools for the development of economic instruments for pollution control. The costs of various abatement measures are reasonably well characterised. However, assessment of the economic costs of pollutant impacts is less well developed. This paper reports on two studies carried out for DGXII of the European Commission, the ExternE-Project and the Green Accounting Research Project. Both studies have been performed by international, multi-disciplinary research teams.Analysis of the effects of emissions of PM10, SO2, NOx and VOCs (as ozone precursors) has included assessment of human health, materials, crops and other terrestrial ecosystems, and freshwater fisheries. The analysis follows the impact pathway approach, linking dose-response functions, valuation data and other models. It differs significantly to earlier top-down approaches that made only very limited use of the wealth of scientific data available. Most success has been achieved in analysis of impacts on human health, building materials and crops. Significant uncertainties exist for these receptors, though these have been identified and are now being addressed. Assessment of impacts on other receptors, perhaps most notably forests, is more limited. The methodology is particularly applicable for analysis of impacts on receptors for which the critical loads approach is not appropriate.  相似文献   

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