基本原理,概念及评估办法

引言 人们普遍认为,全球气候变暖在北极将进一步放大,由于平流层臭氧修复的可能延误,紫外线B(UV-B)辐射可能继续增加,北极环境及其居民可能特别易受这类环境变化的影响.上述共识促进了对气候变化影响的国际评估工作.北极气候影响评估(ACIA)是一项为时4年的研究,结果出版了一篇重要的科研报告[1]并产生了其他的成果.在本文以及本期Ambio专刊下面的文章中,我们提供了报告中针对北极陆地生态系统(从树线群落交错带到极地荒漠)的部分研究成果.     

The effects of congestions tax on air quality and health

The “Stockholm Trial” involved a road pricing system to improve the air quality and reduce traffic congestion. The test period of the trial was January 3–July 31, 2006. Vehicles travelling into and out of the charge cordon were charged for every passage during weekdays. The amount due varied during the day and was highest during rush hours (20 SEK = 2.2 EUR, maximum 60 SEK per day). Based on measured and modelled changes in road traffic it was estimated that this system resulted in a 15% reduction in total road use within the charged cordon. Total traffic emissions in this area of NO_x and PM10 fell by 8.5% and 13%, respectively. Air quality dispersion modelling was applied to assess the effect of the emission reductions on ambient concentrations and population exposure. For the situations with and without the trial, meteorological conditions and other emissions than from road traffic were kept the same. The calculations show that, with a permanent congestion tax system like the Stockholm Trial, the annual average NO_x concentrations would be lower by up to 12% along the most densely trafficked streets. PM10 concentrations would be up to 7% lower. The limit values for both PM10 and NO₂ would still be exceeded along the most densely trafficked streets. The total population exposure of NO_x in Greater Stockholm (35 × 35 km with 1.44 million people) is estimated to decrease with a rather modest 0.23 μg m^?3. However, based on a long-term epidemiological study, that found an increased mortality risk of 8% per 10 μg m^?3 NO_x, it is estimated that 27 premature deaths would be avoided every year. According to life-table analysis this would correspond to 206 years of life gained over 10 years per 100 000 people following the trial if the effects on exposures would persist. The effect on mortality is attributed to road traffic emissions (likely vehicle exhaust particles); NO_x is merely regarded as an indicator of traffic exposure. This is only the tip of the ice-berg since reductions are expected in both respiratory and cardiovascular morbidity. This study demonstrates the importance of not only assessing the effects on air quality limit values, but also to make quantitative estimates of health impacts, in order to justify actions to reduce air pollution.     

Variability in Three Finnish Integrated Acidification Models

Integrated assessment models have been used to support ofnegotiations for further emission reductions of acidifyingcompounds in Europe. More attention is being paid to theuncertainties in integrated models. Data from three Finnishintegrated acidification models were compiled to estimate thevariation and relative importance of different modules. Themodels included site-specific and regional dynamic simulationsand steady-state critical load calculations for forest soilsand lakes. The main emphasis was on the variability ofemissions and the uncertainties in ecosystem effects. Althoughmaximum technically feasible emission reduction measures cantheoretically result in very low deposition, the variabilitybetween realistic scenarios is rather restricted. Thevariability of deposition loading is largely determined byreductions in nearby emission sources. The dynamicsimulations, which are often based on detailed input data,seem to retain larger variability than steady-state criticalload approaches. This study suggests that the uncertainties ineffects seem to be larger generally than other modules ofintegrated acidification models. The results indicate the needfor further work on uncertainty analysis for integrated modelsand the availability of useful model systems for furtherconfirmation of ecosystem effects.     

Evaluating threats to an endangered species by proxy: air pollution as threat to the blue swallow (<Emphasis Type="Italic">Hirundo atrocaerulea</Emphasis>) in South Africa

Background, aim, and scope  

The blue swallow (Hirundo atrocaerulea) is one of the most threatened bird species in southern Africa. Among terrestrial birds, its plumage is known to be the most water repellent, an adaptation to foraging on the wing in dense fog. Despite this unique adaptation, the nesting success of the blue swallow at the Blue Swallow Natural Heritage Site (BSNHS) is lower during years with high incidence of fog. As the phenomenon is not observed at other nesting sites, we hypothesized that this is due to changes in the air chemistry at the BSNHS. In the immediate proximity of the BSNHS, plantations of exotic trees (e.g., pines and eucalypts), rich in volatile organic compounds (VOCs), are dominant features. In addition, air pollution from the Johannesburg area is transported with the surface winds and mix with VOCs released from exotic trees. Together with the high humidity and high elevation, these conditions may result in the formation of sulphonates. Sulphonates are strong detergents, and the presence of these in the fog could lead to decreased water repellence of the plumage. This study was performed in order to determine the occurrence and distribution of sulphonates in the BSNHS and to compare these with sulphonates formed in other locations in South Africa. Because the blue swallow is endangered, pine needles were used as proxy to detect formation of sulphonates.     

Is levoglucosan a suitable quantitative tracer for wood burning? Comparison with receptor modeling on trace elements in Lycksele, Sweden

Particle emissions from residential wood combustion in small communities in Northern Sweden can sometimes increase the ambient particle concentrations to levels comparable to densely trafficked streets in the center of large cities. The reason for this is the combination of increased need for domestic heating during periods of low temperatures, leading to higher emission rates, and stable meteorological conditions. In this work, the authors compare two different approaches to quantify the wood combustion contribution to fine particles in Northern Sweden: a multivariate source-receptor analysis on inorganic compounds followed by multiple linear regression (MLR) of fine particle concentrations and levoglucosan used as a tracer. From the receptor model, it can be seen that residential wood combustion corresponds with 70% of modeled particle mass. Smaller contributions are also seen from local nonexhaust traffic particles, road dust, and brake wear (each contributing 14%). Of the mass, 1.5% is explained by long-distance transported particles, and 2% derives from a regional source deriving from either oil combustion or smelter activities. In samples collected in ambient air, a significant linear correlation was found between wood burning particles and levoglucosan. The levoglucosan fraction in the ambient fine particulate matter attributed to wood burning according to the multivariate analysis ranged from < 2% to 50%. This is much higher than the fraction found in the emission from the boilers expected to be responsible for most emissions at this site (between 3% and 6%). A laboratory emission study of wood and pellet boilers gave 0.3% wt to 22% wt levoglucosan to particle mass, indicating that the levoglucosan fraction may be highly dependent on combustion conditions, making it uncertain to use it as a quantitative tracer under real-world burning conditions. Thus, quantitative estimates of wood burning contributions will be very uncertain using solely levoglucosan as a tracer.     

An approach to assessing sustainability integration in strategic decision systems for product development

This article aims to explore a new approach to assess company decision systems regarding sustainability-related communication and decision support between senior management and product development levels. The assessment approach was developed in theory and its applicability was directly tested in action research in two small and medium-sized companies and two large companies. The results were validated against experiences made by two management consultancies. Our study indicates that successful companies should: (i) integrate sustainability into business goals and plans, backed up by suitable (ii) internal incentives and disincentives and (iii) decision support tools. Our study also indicates that the new assessment approach can be used as a template to assess the current state of sustainability integration in company decision systems.     

Life Cycle Assessment of fossil energy use and greenhouse gas emissions in Chinese pear production

A Life Cycle Assessment (LCA) was performed to analyze environmental consequences of different pear production chains in terms of fossil energy use and greenhouse gas (GHG) emission in China. The assessment identified hotspots that contributed significantly to the environmental impacts of pear production from the cradle to the point of sale. The results showed that GHG emissions and fossil energy use varied in the different production chains because the environmental performance does not associate with the farming systems (i.e. organic vs. conventional), but is co-determined by farm topography and thus machinery use, by market demands to seasonality of products and thus the need for storage, and by local farming practices including manure management. The LCA could be used as a tool to guide selections of agricultural inputs with the aim of reducing environmental impacts. The results of the LCA analysis indicate that a list of choices are available to reduce energy use and GHG emission in the pear production chain, namely substitution of the traditional storage systems by an efficiently controlled atmosphere storage system, using manure for biogas production, conversion from the conventional farming to organic farming, and reduction of mechanical cultivation.