Results 1 - 10 of 64
Results 1 - 10 of 64. Search took: 0.029 seconds
|Sort by: date | relevance|
[en] The Brazilian sandy coastal plain named restinga is frequently subjected to particulate and gaseous emissions from iron ore factories. These gases may come into contact with atmospheric moisture and produce acid rain. The effects of the acid rain on vegetation, combined with iron excess in the soil, can lead to the disappearance of sensitive species and decrease restinga biodiversity. The effects of iron ore dust deposition and simulated acid rain on photosynthesis and on antioxidant enzymes were investigated in Eugenia uniflora, a representative shrub species of the restinga. This study aimed to determine the possible utility of this species in environmental risk assessment. After the application of iron ore dust as iron solid particulate matter (SPMFe) and simulated acid rain (pH 3.1), the 18-month old plants displayed brown spots and necrosis, typical symptoms of iron toxicity and injuries caused by acid rain, respectively. The acidity of the rain intensified leaf iron accumulation, which reached phytotoxic levels, mainly in plants exposed to iron ore dust. These plants showed the lowest values for net photosynthesis, stomatal conductance, transpiration, chlorophyll a content and electron transport rate through photosystem II (PSII). Catalase and superoxide dismutase activities were decreased by simulated acid rain. Peroxidase activity and membrane injury increased following exposure to acid rain and simultaneous SPMFe application. Eugenia uniflora exhibited impaired photosynthetic and antioxidative metabolism in response to combined iron and acid rain stresses. This species could become a valuable tool in environmental risk assessment in restinga areas near iron ore pelletizing factories. Non-invasive evaluations of visual injuries, photosynthesis and chlorophyll a fluorescence, as well as invasive biochemical analysis could be used as markers.
[en] Acid deposition models are inherently simplified representations of real world behaviour and their performance is best evaluated by comparison with observations. National and international acid rain policy assessments handle observed and modelled deposition fields in different ways. Here, both the observed and modelled deposition fields are seen as uncertain and the Generalised Likelihood Uncertainty Estimation (GLUE) framework is used to choose acceptable sets of model input parameters that minimise the differences between them. These acceptable sets of model parameters are then used to estimate deposition budgets to the UK and to provide a probabilistic treatment of excess deposition over environmental quality standards (critical loads). - Uncertainties in modelled depositions of S and N to the UK are quantified and their implications for planned emissions reductions considered
[en] 'Full text': Fossil fuels (i.e., petroleum, natural gas and coal), which meet most of the world's energy demand today, are being depleted quickly. Also, their combustion products are causing global problems such as the greenhouse effect, ozone layer depletion, acid rains and pollution, all of which are posing great danger for our environment and eventually for the life on our planet. Many engineers and scientists agree that the solution to these global problems would be to replace the existing fossil fuel system by the hydrogen energy system. Hydrogen is a very efficient and clean fuel. Its combustion will produce no greenhouse gases, no ozone layer depleting chemicals, and little or no acid rain ingredients and pollution. Hydrogen, produced from renewable energy (e.g., solar) sources, would result in a permanent energy system which we would never have to change. However, there are other energy systems proposed for the post-petroleum era, such as a synthetic fossil fuel system. In this system, synthetic gasoline and synthetic natural gas will be produced using abundant deposits of coal. In a way, this will ensure the continuation of the present fossil fuel system. The two possible energy systems for the post-fossil fuel era (i.e., the solar-hydrogen energy system and the synthetic fossil fuel system) are compared with the present fossil fuel system by taking into consideration production costs, environmental damages and utilization efficiencies. The results indicate that the solar-hydrogen energy system is the best energy system to ascertain a sustainable future, and it should replace the fossil fuel system before the end of the 21st century. (author)
[en] The aim of this study is to recognize the process of flue gas treatment from the coal burning in a steam power plant system. The coal burning will produce flue gas that contains SO_x and NO_x that can cause acid rain which is not safe for environment. A study using comparison method, conventional process and irradiation process from electron beam machine (MBE) system, has been implemented. The study shows that the flue gas produced by coal burning that contains SO_x and NO_x can be processed further using irradiation of MBE to become safe for environment. The process using irradiation of MBE is more efficient than the conventional process, because it requires limited area for the process and the reduction process of SO_x and NO_x is done simultaneously. Moreover, using the optimal parameter process will produce the maximal result. (author)
[en] Canada and the United States committed to reducing the impact of transboundary air pollution through the United States-Canada Air Quality Agreement (AQA) in 1991. Specific objectives related to reducing the emissions of the acid rain precursors sulfur dioxide (SO2) and nitrogen oxides (NOx) were established, as well as commitments to reduce volatile organic compounds (VOCs) and ozone-forming air pollutants. This progress report discussed new actions undertaken by both countries in the last 2 years to address transboundary air pollution, acid rain, and ozone depletion. Air quality efforts made by government agencies were outlined, and details of scientific and technical programs were outlined. Acid deposition monitoring and modelling techniques were discussed, as well as methods used to ensure compliance. Additional control measures and indicative reductions were also provided. Emission inventories and trends were presented, as well as details of individual research programs in the Great Lakes Basin airshed and the Georgia Basin-Puget Sound international airshed. It was concluded that both countries remain committed to the AQA. 2 tabs., 39 figs.
[en] Ramalina maciformis and Ramalina lacera were exposed to different solutions and UV-B to seek for alterations in the PSII photosynthetic quantum yield (F v/F m), in response to chemicals and radiation. For R. maciformis, significant alterations of the F v/F m ratio occurred only in response to different bisulphite solutions. The F v/F m ratio decreased most in R. maciformis and R. lacera following exposure to 5 and 1 mM bisulphite, respectively. Significant differences in F v/F m ratios were observed for R. lacera in response to different solutions and light at different wavelengths, this being synergistic. The PSII system was unaffected by simulated acid rain in both lichens. R. maciformis, in particular, may survive limited acid rain exposure owing to high Ca oxalate accumulation. The F v/F m ratio decreased most in R. lacera following short-term exposures to CuSO4, suggesting that this species is more sensitive to Cu ions under acidic conditions. - Lichens in the eastern Mediterranean tolerate acid rain owing to high Ca content in the thallus, but are sensitive to bisulphite
[en] The Netherlands Environmental Assessment Agency has recalculated the deposition of potential acid and nitrogen in the Netherlands for the period of 1981 through to 2002. Although the Dutch Empirical Acid Deposition Model (DEADM) was used for many years, several changes in the methodology in the course of time led to calculated depositions that were not always comparable. The new approach, fully based on calculations with the Operational Priority Substances (OPS) model, resulted in a deposition data series consistent for the whole 1981 - 2002 period. The recalculated acid deposition came to 10-20% lower, a difference which in absolute numbers comes to a maximum of 1550 mol per hectare per year when compared with the old data for the 1981 to 1987 period. The differences for 1988 through 1993 are just the opposite: recalculated depositions are 5 to 10% higher than in the old data. From 1993 onward differences were only minor. Calculations with OPS showed the acid deposition to decline from 6000 mol per hectare per year in 1981 to 3000 mol per hectare per year in 2002. The deposition of oxidised sulphur (SOx) showed the sharpest decline: minus 75%, down to 400 mol in 2002. The deposition of oxidised nitrogen (NOy) declined by 30%, to 700 mol per ha per year, along with that of reduced nitrogen (NHx), declining from 30% to 1500 mol per ha per year. The resulting nitrogen deposition declined from 3100 mol to 2200 mol, a reduction of 30%
[nl]Het Milieu- en Natuurplanbureau heeft de deposities van potentieel zuur en stikstof in Nederland voor de periode 1981 tot en met 2002 opnieuw berekend. Jarenlang werd hiervoor DEADM, het Dutch Empirical Acid Deposition Model, gebruikt. In de loop van de tijd zijn diverse correcties op DEADM aangebracht. Deze zijn echter door de jaren heen niet altijd consequent uitgevoerd. De berekende deposities van verschillende jaren waren daardoor niet altijd goed vergelijkbaar. De nieuwe aanpak is geheel gebaseerd op berekeningen met het Operationeel Prioritaire Stoffen (OPS) model. De nieuwe berekeningswijze heeft nu over de gehele periode van 1981 tot en met 2002 een consistente reeks van depositiegetallen opgeleverd. De herberekende verzurende depositie is voor de jaren 1981 tot en met 1987 10 tot 20% lager dan volgens de eerdere berekeningen. Het verschil bedraagt maximaal 1550 mol per hectare. Voor de jaren 1988 tot 1993 liggen de verschillen juist andersom: de herberekende depositie is 5 tot 10% hoger dan in de oude berekeningen. Vanaf 1993 zijn de verschillen gering; er zijn daarom geen beleidsconsequenties
[en] This paper focuses on environmental mercury emissions in Asia and elaborates its probable trend in the future and associated implications given the anticipated socioeconomic outlook and other macro-environmental factors. Among the various regions, Asia has become the largest contributor of anthropogenic atmospheric Hg, responsible for over half of the global emission. In the next few decades, a significant increase in anthropogenic Hg emissions in Asia is likely owing to rapid economic and industrial development, unless drastic measures are taken. In particular, the dominance of Asia in some Hg-emitting industries, such as coal combustion, steel production and gold mining, provokes a serious environmental concern over their potential contributions of incidental Hg in the region. Moreover, the increasing prevalence of electrical and electronic manufacturing industry as a user and a contributor of Hg in Asia is also worrying. Specifically, disposal of obsolete electrical and electronic wastes represents a phenomenon increasingly encountered in Asia. In addition to escalating anthropogenic Hg emissions in Asia, associated environmental and health implications may also exacerbate in the region for the probable effects of a unique combination of climatic (e.g. subtropical climate), environmental (e.g. acid rain) and socioeconomic factors (e.g. high population density). Hence, much effort is still needed to understand the role of Asia in global Hg cycle and associated environmental and health effects in the region
[en] Acid rain continues to be a major problem in North America, and particularly in eastern Canada. This report introduced the topic of acid rain and discussed its formation, measurement, sources, and geographic distribution. The major sources of sulphur dioxide in Canada are smelting metals, burning coal for electrical power generation, industrial emissions (e.g., pulp and paper, petroleum and aluminum industry), and oil and gas extraction and refining. In Canada, the largest source of nitrogen oxide is the burning of fossil fuels by the transportation sector. Problem areas for acid rain in Canada were identified. The effects of acid rain were examined on lakes and aquatic ecosystems, forests and soils, human-made structures and materials, human health, and on visibility. Acid rain policies and programs were then presented from a historical and current context. Ecosystem recovery from acid rain was discussed with reference to acid rain monitoring, atmospheric response to reductions in acid-causing emissions, and ecosystem recovery of lakes, forests, and aquatic ecosystems. Challenges affecting ecosystem recovery were also presented. These challenges include drought and dry weather, decrease of base cations in precipitation, release of sulphate previously stored in soil, mineralization and immobilization of sulphur/sulphates. Last, the report discussed what still needs to be done to improve the problem of acid rain as well as future concerns. These concerns include loss of base cations from forested watersheds and nitrogen deposition and saturation. 21 refs., 2 tabs., 17 figs
[en] This report highlights the key characteristics of the world's main emission trading schemes, presents a new vision for compliance in emissions trading and calls for global action to develop this. Climate change is now at the top of the political and business agenda. Al Gore's 'An Inconvenient Truth', the Stern Review and the now almost daily press coverage of climate change science and impacts have engaged many of the global leaders in government and in business. Emissions trading is increasingly seen as a central plank in the response to climate change. But market mechanisms like this depend on trust and confidence. Any widespread or systemic failure, as a result of deficient monitoring and reporting, flawed compliance processes or fraud, could undermine confidence in markets and regulation and jeopardise the crucial policy goals that they are designed to address. Key to this trust are the three central criteria of transparency, accountability and integrity. The PricewaterhouseCoopers report looks at how the patchwork of trading schemes that are emerging around the globe stacks up against these criteria. Despite good intentions across the board, the general picture is one of new and immature markets, inconsistent and complex compliance frameworks and risk. PricewaterhouseCoopers make the case for urgent and coordinated action to develop a framework of generally accepted principles and practice that will underpin trust and efficiency in these new markets - in effect, a new Global Emissions Compliance Language