Computer-supported systems analysis for wastewater control cost minimization

This paper demonstrates the use of computer-supported systems analysis in the derivation of least cost responses to municipally generated water pollution. In particular, a computer program is used to identify the least cost solution from a total system perspective by assembling all major treatment options and calculating their associated removal efficiencies and costs. The set of possible solutions consists of representative forms of industrial pretreatment together with the option to hook each major discharger to the municipal sewage treatment plant. In the example used in this paper, the optimization process identifies several alternatives that are less expensive than all industry hook-up with no pretreatment. The paper also briefly discusses the related issues of cost recovery and the economic efficiency of alternative effluent fee systems.     

Forecast of Sulfur Deposition in Japan for Various Energy Supply and Emission Control Scenarios

In order to contribute to the analysis and solution of regional scale environmental problems in East Asia, we developed a tool for the comprehensive assessment of alternative policy options to improve air quality. This tool projects the future regional energy supply, calculates the emission levels of sulfur dioxide and estimates the geographical pattern of sulfur deposition resulting from emissions. Sulfur deposition in Japan through 2030 was forecasted for various energy supply and emission control scenarios using the analysis tool. Future sulfur depositions were calculated from the source-receptor matrix for 1995 and the growth rate of emission for the source subregion. In the case of the current legislation scenario, anthropogenic SO₂ emissions in East Asia would grow by 34 percent and sulfur deposition in Japan would increase by approximately 20 percent between 1995 and 2030. This increase in sulfur deposition over these 35 years is sligthly less than the contribution from volcanic emission to sulfur deposition in Japan. In the case of the hypothetical dirty scenario for China, sulfur deposition in several grids which face the Sea of Japan would double by 2030.     

Greenhouse gas mitigation potential of agricultural land in Great Britain

The aim of this paper is to assess the greenhouse gas (GHG) mitigation potential of croplands and grasslands in Great Britain under different management practices. We consider the feasible land management options for grass and cropland using county level land‐use data with estimates of per‐area mitigation potential for individual and total GHGs, to identify the land management options with the greatest cost‐effective mitigation potential. We show that for grasslands, uncertainties still remain on the mitigation potential because of their climatic sensitivity and also their less intensive management. For croplands in Great Britain, the technical mean GHG mitigation potentials for all cropland management practices range from 17 Mt CO₂‐eq. per 20 yr to 39 Mt CO₂‐eq. per 20 yr. There are significant regional variation in all cases, with the greatest potentials in England, negligible potential in Wales and intermediate potential in Scotland, with country differences largely driven by the areas of cropland and grassland in each country. Practices such as agronomic improvement and nutrient management are the most promising options because of their impact on N₂O emissions and also their larger potential at low cost. In terms of annual emissions from agriculture, calculated mitigation potentials are small, where the technical mitigation potential of agronomy and nutrient management strategies are ca. 4.5 and 3.8%, respectively (agricultural emissions account for ca. 9% or 47.7 Mt CO₂‐eq., of total Great Britain GHG emissions, Department of Energy and Climate Change, UK). However when compared with the land use, land‐use change and forestry sector (LULUCF) emissions, nutrient management would reduce further emission reductions by approximately half of the 2005 LULUCF sink (i.e. ?1.6 Mt CO₂‐eq. per year).     

Acidic deposition — Extent and impact on forest soils,nutrition, growth and disease phenomena in Central Europe: A review

The paper reviews the present knowledge: (1) about the extent of acidic deposition in Central Europe with special emphasis on the situation in the FRG, (2) about the relationships between soils and soil-mediated effects of acidic deposition on the one hand and forest diseases on the other and (3) the temporal changes of relevant soil properties during the past decades. It is concluded, that infertile soils and acidic deposition are more likely to act as regional or local than as widespread general stressors in forest ecosystems of the FRG. The more or less simultaneous outbreak of natural and of pollutant-determined diseases during the early eighties is assumed to be triggered by largescale weather stress.     

Variability in Mapping Acidification Risk Scenarios for Terrestrial Ecosystems in Asian Countries

Acidification has the potential to become a widespread problem in parts of Asia. Just how widespread this risk may be is discussed by comparing sulphur deposition to critical load estimates, taking into account neutralising base cation deposition from soil dust. Two scenarios for the sulphur emission in 2025 are used as inputs to the MATCH atmospheric transfer model to estimate sulphur deposition scenarios. Net acidic deposition using a low and high base cation deposition input is compared to a map of sensitivity of terrestrial ecosystems to acidic deposition. Two ranges of critical loads assigned to this sensitivity map are used. The variability in the maps showing risks of acidification using low and high estimates for critical loads and base cation deposition for two different development pathways is discussed. Certain areas are shown to be at risk in all cases whereas others are very sensitive to the values used to estimate risk.     

European emission data with high temporal and spatial resolution

The estimation of acidic deposition strongly depends on the availability of accurate emission data. The atmospheric models, that calculate concentrations and depositions of pollutants, need data in a high temporal resolution (e.g. daily, 6-hourly or even hourly data). However, although some progress has been achieved concerning annual emission data for Europe (e.g. CORINAIR 90), only very little information is available about the temporal variation of these emissions during a year. Therefore, within the EUROTRAC-GENEMIS project special emphasis was laid on the development of methods to generate emissions with a high temporal and spatial resolution. As results the temporal and spatial distribution of SO₂- and NO_X-emissions are shown. The results indicate, that the emissions vary considerably over time and that the use of simple patterns for the temporal disaggregation is not sufficient for modelling and assessment of acidic deposition.     

A Literature Review of Uncertainties in Studies of Critical Loads for Acidic Deposition

Uncertainties in the assessment of critical loads for acidic deposition are caused by the choice of biological indicators (BI), critical chemical values (CCV), the current methods used to determine critical loads for an ecosystem, and deficient field data. This paper focuses on the present steady-state mass balance (SSMB) approach, dynamic models and the importance of changes in atmospheric base-cation deposition (BCD), particularly in China. It is argued that 1) for the SSMB approach much uncertainty may come from the choice of BI and the related CCV, and long-term and large-scale monitoring data on weathering rates and growth uptake are urgently needed, especially in China, 2) significant uncertainty may be caused by changes in BCD during SO₂ emission controls, particularly in China, 3) constructing a mechanistic Al submodel may be a promising direction for dynamic models, and 4) the nutrient cycle in the vegetation through biogeochemical processes should be incorporated into dynamic models but the input requirements should be moderate for broad application considerations. Generally higher BCD, different soil components and characteristics and different vegetation types in China compared to Europe and North America suggest that more field investigations on BI and their corresponding CCV be carried out before application of current approaches to specific areas, particularly in China.     

Critical loads of sulfur and nitrogen for lakes II: Regional extent and variability in Finland

The concept of critical loads has been developed to assist in the design of environmentally sound abatement strategies for the emissions of acidifying compounds. In this paper the critical loads of S and N for lakes in Finland are computed and mapped, based on methods presented in an accompanying paper. The employed steady-state mass balance model allows the simultaneous evaluation of the reductions required of S and N deposition exceeding these critical loads. Special emphasis has been put on the presentation of the spatial variability and the uncertainty of the critical loads and their exceedances. The derived critical loads of S and N for lakes in Finland show a substantial spatial variability. The highest exceedance of critical loads is presently estimated in the south-east of the country, where up to 80% of the lakes show an exceedance of the critical loads of S. The evaluation of two emission scenarios shows that only “maximum feasible reductions” would be sufficient for protecting most Finnish lakes from the impacts of acidic deposition. The results of this study form a basis for setting national targets for emission reductions in Finland.     

Sudbury smelter impact on atmospheric deposition of acidic substances in Ontario

During the period from June 1982 to March 1983, there was a prolonged shutdown of the INCO and Falconbridge smelters at Sudbury, Ontario. Taking advantage of this opportunity, the Air Resources Branch of the Ontario Ministry of the Environment undertook a detailed analysis of the impact that the resulting emission reductions had on the atmospheric deposition of acidity and SO_X in Ontario. This paper summarizes the various meteorological analyses and mathematical modeling estimates that were carried out in order to determine the contribution of the Sudbury smelters to atmospheric deposition in Ontario. For sulfates, the Sudbury contribution to the total wet deposition was typically less than 15% at the receptors studied. Furthermore, the smelters were found to contribute on the order of 10 to 20% of the total dry deposition of S compounds in central and northeastern Ontario, and less than 10% elsewhere.     

Energy use,emissions, and air pollution reduction strategies in Asia

In contrast to Europe and North America, air pollution in Asia is increasing rapidly, resulting in both local air quality problems and higher acidic depositions. In 1989, an east-west group of scientists initiated a multi-institutional research project on Acid Rain and Emissions Reduction in Asia, funded for the past two years by the World Bank and the Asian Development Bank. Phase I, covering 23 countries of Asia, focussed on the development of PC-based software called the Regional Air Pollution INformation and Simulation Model (RAINS-ASIA). A 94-region Regional Energy Scenario Generator was developed to create alternative energy/emission scenarios through the year 2020. A long-range atmospheric transport model was developed to calculate dispersion and deposition of sulfur, based upon emissions from area and large point sources, on a one-degree grid of Asia. The resulting impacts of acidic deposition on a variety of vegetation types were analyzed using the critical loads approach to test different emissions management strategies, including both energy conservation measures and sulfur abatement technologies.     

Regional Air Pollution and Climate Change in Europe: an Integrated Assessment (Air-Clim)

The aim of the AIR-CLIM project is to perform an integrated analysis of the linkages between climate change and regional air pollution in Europe and to produce results that are relevant to European policy-making. Key elements of the analysis are on the impact side the exceedances of critical thresholds for air pollution and global change and on the cost side the estimates of costs to reduce emissions of greenhouse gases and air pollutants. The integrated modeling framework set up to meet these objectives consists of two state-of-the-art integrated models covering regional air pollution in Europe (RAINS) and global climate change (IMAGE), supplemented by new components. Based on a preliminary analysis it can be stated that climate change will make European vegetation in most regions less sensitive to acid deposition. Taking into account the emission trends the impacts of regional air pollution will decrease while the impacts of climate change increase. Different problems will be important in different regions: regional air pollution in Central and northern Europe, and climate change in southern Europe.     

Optimization of emission reductions to reduce atmospheric sulphur deposition in Europe: An examination of a methodology

An examination has been made of the use of the LRT model of the Norwegian Meteorological Institute, which estimates the atmospheric exchanges of sulphur among 28 countries in Europe, to formulate optimized emission reduction scenarios. According to the methodology, emission reductions are needed in at least several countries to bring about a deposition reduction in a given country. However, it is most effective to reduce emissions in or near the country where deposition reductions are desired. To reduce deposition further, it is more effective to further reduce nearby emissions, rather than to seek additional emission reductions farther afield. Because of the complex distribution of strong source regions in Europe, an assessment of the advantages of an optimized emission reduction pattern over a uniform reduction scheme must await the better definition of deposition targets and the location where they are to be applied.     

The influence of organic acidity on the acid-base chemistry of surface waters in Maine,USA

Results from surveys of low-ANC lakes (high elevation, and seepage lakes), and of surface waters in dystrophic, acidic bogs, indicate that acidic precipitation and organic acidity are each generally necessary, but not solely sufficient, for chronically acidic status in Maine lakes. Acidic, low DOC (ANC < 0; DOC < 5 mg L^-1) lakes of all hydrologic types are acidic due largely to acidic deposition; high DOC (DOC > 30 mg L^-1) acidic seepage lakes are acidic due largely to organic acidity, and high DOC drainage lakes are acidic due to a combination of both factors. No low DOC drainage lakes are known with pH less than about 5.0, suggesting that organic acidity is necessary to depress lake pH values to below 5 in Maine at current deposition loadings,The dominant anion of low DOC, acidic waters is sulfate. Acidic waters with intermediate concentrations of DOC (5 to 30 mg L^-1), may be dominated by S04 and/or organic acidity. Seepage-input lakes were the only group to include both organically-dominated (37% of the acidic lakes) and S0₄-dominated members (63% of the acidic lakes). High DOC systems are typically low pH bogs, and are all organic acid-dominated.     

农作措施对中国稻田氧化亚氮排放影响的研究进展

农业是全球最主要的温室气体排放源之一,稻田不仅是全球重要的甲烷(CH4)排放源,亦是氧化亚氮(N2O)的重要排放源。灌溉、施肥、耕作等农作措施能够改变稻田生态系统土壤微环境,影响土壤硝化与反硝化过程,进而影响N2O的排放。目前,关于农作措施对农田生态系统N2O排放特征研究很多,但系统地综述农作措施对稻田N2O排放影响的研究还比较少。该文着眼于中国的农业发展趋势,基于稻田灌溉、施肥及耕作等方面的新技术,综合分析新型农作措施对中国稻田生态系统N2O排放的影响及其机制,为相关研究提供参考。在此基础上,提出了中国稻田生态系统N2O排放深入研究的方向:1)加强研究新型农作措施下稻田N2O产生及排放途径;2)系统研究稻田生态系统直接与间接N2O排放的影响及其机制;3)开展农作措施集成技术对稻田生态系统N2O排放影响的研究;4)加强模型模拟的调参验证并进行相关预测分析。     

Marine algae as a co2 sink

The most effective ways to reduce CO₂ emissions are to improve the energy efficiency of each economic sector and to reduce the cutting of tropical and temperate forests around the world. These options, however, may not fully reach their technical and economic potential due to various political and socioeconomic barriers. Other more innovative and less well developed mitigation measures therefore will be required. The most practical of these is to increase CO₂ sinks through photosynthesis in both standing tree biomass and in ocean primary producers. In this paper, the use of marine algae as CO₂ sinks is reviewed from a technical, engineering/economic, and environmental perspective. Two open ocean options are considered for large-scale CO₂ mitigation: the use of phytoplankton through Fe fertilization and macroalgal (kelp) farms, which can be used for both C sequestering and energy production. It has been estimated that these two approaches can sequester from 0.7 to 3 Gt C yr^?1 from the atmosphere at an estimated cost of $5 to 300 t^?1 C yr^?1. Other options currently under study are also mentioned. Numerous questions remain to be answered pertaining to the use of both microalgae and macroalgae for CO₂ assimilation before credible estimates of costs of C removal can be made for either system. In addition, there are several key environmental issues raised by the use of algae. A detailed discussion of these variables, including cost estimates, is presented.     

LONG-TERM CHANGES IN FOREST SOIL ACIDITY IN PENNSYLVANIA,U.S.A.

Forest soil acidification has been reported to cause reduced forest productivity and decline of some tree species. Soil acidification may cause increased bioavailability of Al and Mn, which are potentially phytotoxic. In an attempt to measure whether or not Pennsylvania forest soils have become more acidic, soil samples were collected at 11 undisturbed forested sites in Pennsylvania in 1993. Limited soil chemistry data obtained through 4 previous studies conducted between 1957 and 1979 were available for each site. Soil pH and concentrations of exchangeable Ca and Mg were measured; results were compared to those obtained in earlier studies. Soil exchangeable Al concentrations were determined for 6 sites for which previous data were available. Chemical analysis methods were evaluated to ensure that methods used in 1993 were comparable to those of the original investigators. Mean pH and exchangeable Mg declined most consistently over the study period in the O horizon and the uppermost A horizon. Mean exchangeable AI decreased in the O horizon and increased in the A horizon. Given the high sulfate and nitrate deposition loads in Pennsylvania, it seems likely that the observed changes are at least in part a consequence of acidic deposition.     

Acidification in Norway — Status and trends biological monitoring — Improvements in the invertebrate fauna

The Norwegian monitoring programme of acidification include studies of invertebrates, which started in 1981. The invertebrate programme is based on kick samples from a fixed station net in 8 river systems. The stations include tributaries as well as stations in the main river. This paper deals with three rivers located in a gradient covering the range of acidic deposition in West Norway. The invertebrates are identified to species level and sorted with respect to acid sensitive and acid tolerant species, used for stating an acidification index. The spring samples generally show the highest acidification due to release of acids during snow smelt. In fall the acidity was lower and the index was less variable. A significant increase in the acidification index (reduced acidity) was recorded during fall in the period 1989 – 94 in two of the watersheds. In the third watershed no significant trend was recorded. During the years 1982 – 1988 a significant increase in the index occurred in spring in the watershed with lowest acidic deposition. The increases observed in the index is probably a result of the reductions in acid deposition in Norway.     

A gaussian-box modeling approach for urban air quality management in a Northern Chinese City—II. pollutant emission abatement

A modeling framework by linking air quality simulation with system optimization was presented in this paper to develop cost-effective urban air quality management strategies in Fengnan district of China. The relation between the total allowable emission and wind speed as well as the relation between the total allowable emission and air-quality-guideline satisfaction were quantified based on the simulation results of the Gaussian-box modeling system. The area-source emission reduction objective in each functional zone of the study city during the heating and non-heating seasons was calculated based on such relations. A linear programming model was then developed to optimize the emission abatement which was subject to a number of dust and SO₂ control measures. The economic objective of the air quality management strategy was to minimize the total emission control system cost while the environmental objective can still be satisfied. The environmental objective was reflected by the emission reduction objective of TSP, PM₁₀ and SO₂ corresponding to an air-quality-guideline satisfaction percentage of 80%. Consequently, the modeling system comprehensively took into account the information of emission reduction objectives, emission abatement alternatives, emission reduction cost, and related resources constraints. An optimal emission abatement strategy and the related cost were obtained for various pollution control measures. The results would provide sound bases for decision makers in terms of effective urban air quality management and ensuring healthy economic development in the study city.     

Emission Inventories,Emission Control Options and Control Strategies: An Overview of Recent Developments

Accurate emission inventories are crucial for informed decisions about emission control strategies. Emission inventory activities are now well established throughout the world and a large body of resources is available to assist in estimating emissions at the global, regional and local scale. Work is ongoing to refine methodologies and to address additional sources and pollutants such as fine particulate matter. During the last decade innovative concepts for emission control legislation were developed. Market based instruments can achieve envisaged emission reductions at lower costs than conventional approaches. Air quality management is now understood as a multi-pollutant, multi-effect task, which offers a significant cost saving potential if synergistic effects are fully utilized. Integrated assessment models proved useful in managing the vast volume of relevant information needed for the design of cost-effective emission control strategies. Europe and North America have embarked on ambitious control strategies that will lead to significant reductions in the emissions of some of the conventional pollutants (e.g., SO₂, NO_x, VOC). There are also first indications of a structural break that could reverse the long-term growth trend of SO₂ emissions also in the fast developing nations of Asia.