An overview of environmental hazards and exposure risk of hydrofluorocarbons (HFCs)

Hydrofluorocarbons (HFCs) are being used as replacements for chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) that cause significantly stratospheric ozone depletion and global warming. HFCs under commercial uses as cleaning solvents in the electronic components, blowing agent in the foamed plastics, refrigerant in the air conditioning units and refrigerators, fire suppression agent in the fire protection, propellant in the metered dose inhalers (MDIs), and dry etching agent in the semiconductor manufacturing. Among these HFCs, 1,1,1,2-tetrafluoroethane (HFC-134a) is the most widely used one. From the environmental, ecological, and health points of view, it is urgent to mitigate and control the emissions of these HFCs from a diversity of commercial applications and industrial processes. This article aims to introduce these HFCs in commercial uses and environmental hazards (i.e., global warming, photochemical potential, flammability safety, environmental partition and ecotoxicity). Further, the updated data on the human toxicity, occupational exposure and health risk of these HFCs (esp., HFC-134a) are addressed in this review paper.     

Global emissions of HFC-23 estimated to year 2015

HFC-23 (trifluoromethane, fluoroform, CHF₃) is a powerful greenhouse gas that is formed at the reactor stage of the manufacture of HCFC-22 (chlorodifluoromethane, CHClF₂). The amount formed depends on the conditions used in the manufacturing process and, for individual plants, lies between 1% and 4% of the production of HCFC-22. While it is possible to reduce the formation of HFC-23 by optimising process conditions, it is not possible to eliminate its production. This requires destruction, generally by thermal oxidation. Under the Kyoto Protocol, developed countries have obligations to reduce greenhouse gas emissions and, in the developing world, there are projects under the Clean Development Mechanism for the incineration of HFC-23 waste streams. These should lead to a reduction in average global emission factors relative to production of HCFC-22. We present estimates of global production of HCFC-22 up to the year 2015 and also the calculated range of emissions of HFC-23 that may be consequences of this. In terms of the effect on climate change, the atmospheric burden of HFC-23 accumulated from emissions is calculated to contribute between 0.1% and 0.2% of the radiative forcing of climate in 2015. Annual emissions of HFC-23 would be equivalent to between 284 and 28 million tonnes of CO₂ in that year, when total anthropogenic greenhouse gas emissions are predicted to lie between 46,000 million and 59,000 million tonnes of CO₂ equivalent.     

激光类全新耗材和再生耗材对环境影响的生命周期评价

以激光类打印耗材——TN350为例,应用生命周期评价方法,对全新TN350和再生TN350进行生命周期资源消耗与污染物排放清单分析,在此基础上进行生命周期环境影响评价。重点考虑6种环境影响类型：全球变暖、酸化、富营养化、光化学臭氧、固体废弃物、工业烟尘和粉尘。结果表明,相对于全新TN350,再生TN350的原油消耗量削...     

循环流化床锅炉燃煤技术热电厂生命周期评价

运用生命周期评价方法,应用Gabi5.0软件对采用循环流化床锅炉燃煤技术的热电企业进行资源耗竭和环境影响分析,计算各生产单元生命周期清单的全球变暖潜值、酸化效应潜值、富营养化潜值、非生物资源耗竭潜值、人体毒性潜值以及光化学烟雾和臭氧生成潜值等主要环境影响类型,对燃煤发电过程进行生命周期评价。结果表明,全球变暖和非生物资源耗竭为发电运行过程中主要的环境影响因素,分别占53%和15.05%;锅炉燃烧阶段的环境影响最重,占整个生命周期影响值的77.12%,并且除生物耗竭潜值外的其他5项指标均为发电运行阶段各个单元中最高。采用SNCR脱硝技术减少燃烧过程中NOx的排放量,并对该技术方案进行生命周期评价,比较方案实施前后的环境影响。     

Reductive dechlorination of chlorofluorocarbons and hydrochlorofluorocarbons in sewage sludge and aquifer sediment microcosms

The reductive transformation of the 10 most-widely distributed fluorinated volatile compounds and of tetrachloroethene was investigated for up to 177 days under anaerobic conditions in sewage sludge and aquifer sediment slurries. Concentrations of parent compounds and of degradation products were identified by GC-MS. We observed transformation of CFC-11 to HCFC-21 and HCFC-31, of CFC-113 to HCFC-123a, chlorotrifluoroethene and trifluoroethene, of CFC-12 to HCFC-22, of HCFC-141b to HCFC-151b, and of tetrachloroethene to vinyl chloride and ethene. CFC-114, CFC-115, HCFC-142b, HFC-134a and HCFC-22 were not transformed. The results suggest that with both inocula studied here, hydrogenolysis is the primary reductive dechlorination reaction. CFC-113 was the only compound where a dichloro-elimination was observed, leading to the formation of chlorotrifluoroethene as temporal intermediate and to trifluoroethene as end product. The relative reduction rates of chlorofluoromethanes compared reasonably well with theoretical rates calculated based on thermochemical data according to the Marcus theory. Some of the accumulating HCFCs and haloethenes observed in this study are toxic and may be of practical relevance in anaerobic environments.     

Inversion of PM2.5 atmospheric refractivity profile based on AlexNet model from the perspective of electromagnetic wave propagation

Environmental Science and Pollution Research - Human civilization has reached an unprecedented height, but the industrialization of economic development also brings global warming, ozone depletion,...     

LCA of tomato greenhouse production using spatially differentiated life cycle impact assessment indicators: an Albanian case study

The increasing attention to agricultural exports and sustainability issues is driving a surge of interest in the life cycle assessment (LCAs) of greenhouse crop production in Albania. Meanwhile, most of the reported agricultural LCAs tend to be generic without considering regionalized environmental sensitivities. In this study, ReCiPe 2016, covering 18 midpoint indicators and 3 endpoint indicators was used to generate a full-fledged cradle-to-farm gate LCA of greenhouse tomatoes in a typical Albanian farm including spatial differentiation and indicators not covered by contemporary LCAs. The most important midpoint categories per 1 ha identified from foreground–background analysis were global warming (2660.4 kg CO2-eq), stratospheric ozone depletion (0.0308 kg CFC11-eq), particulate matter formation (7.99 kg PM2.5-eq), human health and ecosystem ozone formation (8.47 and 14.95 kg NOx-eq), water consumption (2293.23 m3), and terrestrial acidification (42.28 kg SO2-eq). The application of spatial differentiation resulted in higher impacts with about 21% for particulate matter formation, 12% for human health ozone formation, 134% for ecosystem ozone formation, 19% for terrestrial acidification, and 13% for water consumption. The impacts primarily originated from nitrogen-based fertilizer emissions and diesel fuel with the origin of the impact from nitrous oxide (N2O), ammonia volatilization (NH3), nitrogen oxides (NOx), and non-methane volatile organic compounds (NMVOCs). Water consumption was dominated by irrigation water use. Overall, at the endpoint level, 9% and 24% less cumulative damage to human health and ecosystem quality were calculated with respect to the site-generic analysis primarily from the cause-and-effect chain of water consumption (mainly lower water stress index). This affirms the importance of regional considerations in LCA calculations to reflect the impacts accordingly (i.e., the magnitude of impacts, the most relevant midpoint categories, and their relevance on endpoint level) and increase the possibility of making correct conclusions and sub-optimizations, i.e., increase the discriminating power of LCA.     

2种典型餐厨垃圾资源化处理工艺的环境影响分析

为了评估餐厨垃圾资源化处理工艺对环境的影响,运用生命周期评价的方法,比较了2种典型的资源化处理工艺——好氧堆肥和湿热处理对环境的影响。结果表明,2种餐厨垃圾资源化处理工艺对全球变暖、生态毒性、酸化和富营养化的影响各有不同。其中,好氧堆肥对全球变暖的贡献较大,碳排放为337.7 kg CO_2eq./t。湿热处理为163.1 kg CO_2eq./t。在环境影响负荷方面,湿热处理工艺中的高能耗加重了毒性的影响。但由于其对环境的酸化、富营养化的不利影响较小,湿热处理的环境影响负荷总值是好氧堆肥的62.5%。总体上,湿热处理是一种对环境影响较小的餐厨垃圾处理工艺。     

Tropospheric halocompounds and nitrous oxide monitored at a remote site in the Mediterranean

Analysis of time series and trends of nitrous oxide (N₂O) and halocompounds weekly monitored at the Mediterranean island of Lampedusa are discussed. Atmospheric N₂O levels showed a linear upward growth rate of 0.78 ppb yr^?1 and mixing ratios comparable with Northern Hemisphere global stations. CFC-11 and CFC-12 time series displayed a decline consistent with their phase-out. Chlorofluorocarbons (CFCs) replacing compounds and SF₆ exhibited an increasing temporal behaviour. The most rapid growth rate was recorded for HFC-134a with a value of 9.6% yr^?1. The industrial solvents CCl₄ and CH₃CCl₃, banned by the Montreal Protocol, showed opposite trends. While CH₃CCl₃ reported an expected decay of ?1.8 ppt yr^?1, an increasing rate of 5.7 ppt yr^?1 was recorded for CCl₄ and it is probably related to its relatively long lifetime and persisting emissions. Chlorinated halomethanes showed seasonality with a maximum in early April and a minimum at the end of September. Halon-1301 and Halon-1211 displayed a decreasing trend consistent with industry emission estimates.An interspecies correlation analysis gave positive high correlations between HCFC-22 and HFC-134a (+0.84) highlighting the common extensive employment as refrigerants. Sharing sources inferred the high coupling between CH₃Cl and CH₃Br (+0.73) and between CHCl₃ and CH₂Cl₂ (+0.77). A singular strong relationship (+0.55) between HFC-134a and CH₃I suggested the influence of an unknown anthropogenic source of CH₃I.Constraining of source and sink distribution was carried out by transport studies. Results were compared with the European Environment Agency (EEA) emission database. In contrast with the emission database results, our back trajectory analysis highlighted the release of large amounts of HFC-134a and SF₆ from Eastern Europe. Observations also showed that African SF₆ emissions may be considerable. Leakages from SF₆ insulated electrical equipments located in the industrialized Northern African areas justify our observations.     

中国与全球性环境问题

本文系作者对中国环境问题十几年研究成果的总结。作者重点阐述了全球环境问题、地球变暖与中国的现状、酸雨与中国的现状、臭氧层破坏与中国现状、野生生物种的灭绝与中国现状等。     

Comparison of emissions estimates derived from atmospheric measurements with national estimates of HFCs,PFCs and SF6

This paper assesses the feasibility of using atmospheric measurement of fluorinated greenhouse gases (HFCs, PFCs and SF6) for the review and verification of greenhouse gas inventories provided by national governments. For this purpose, available data were compiled. It was found that atmospheric measurements of these gases are available and provide an indication of global annual emissions with sufficient certainty to reach the following conclusions: Within the uncertainty of the method, it was found that emissions of HFC-23, a by-product of HCFC-22 production, as obtained from atmospheric measurements did not decrease as fast, as the countries have reported. In contrast, SF6 concentrations in the atmosphere suggest higher emissions than reported by countries. Regional emission estimates from atmospheric measurements are still in a more pioneering state and cannot be compared to national estimates. Intensified efforts to measure HFCs, PFCs and SF6 in the atmosphere are recommended.     

CEPA—The Canadian. Environmental Protection Act

CEPA, the Canadian Environmental Protection Act, is a law of the Parliament of Canada that provides a framework for protecting Canadians from all forms of pollution caused by toxic substances. CEPA improves the federal government’s ability to manage chemical substances. The approach is comprehensive. It encompasses the entire life cycle of toxic substances— from their development and manufacture, through the stages of transport, distribution, use, and storage, to their ultimate disposal. CEPA not only guarantees a safer environment for all Canadians, it also provides for better enforcement and tougher punishment of polluters than ever before.     

Global change: state of the science

Only recently, within a few decades, have we realized that humanity significantly influences the global environment. In the early 1980s, atmospheric measurements confirmed basic concepts developed a decade earlier. These basic concepts showed that human activities were affecting the ozone layer. Later measurements and theoretical analyses have clearly connected observed changes in ozone to human-related increases of chlorine and bromine in the stratosphere. As a result of prompt international policy agreements, the combined abundances of ozone-depleting compounds peaked in 1994 and ozone is already beginning a slow path to recovery. A much more difficult problem confronting humanity is the impact of increasing levels of carbon dioxide and other greenhouse gases on global climate. The processes that connect greenhouse gas emissions to climate are very complex. This complexity has limited our ability to make a definitive projection of future climate change. Nevertheless, the range of projected climate change shows that global warming has the potential to severely impact human welfare and our planet as a whole. This paper evaluates the state of the scientific understanding of the global change issues, their potential impacts, and the relationships of scientific understanding to policy considerations.     

Closing Remarks

Considerable attention has been paid in recent years to photochemical smog pollution close to the earth's surface and to stratospheric ozone depletion. There is reason to suspect that the next round of scientific concern will be devoted to the perturbations in the “free troposphere.” Tropospheric ozone has been building up in many regions of the northern hemisphere. Ozone changes in the upper troposphere will exert a considerable impact on global warming. This could affect moisture levels, cloud amount and distribution, precipitation, and atmospheric dynamics on different scales.

This paper analyzes: (1) the physical and chemical processes contributing to changes in tropospheric ozone concentration; (2) the observational evidence of previous ozone change; and (3) results drawn from computer modelling of past and future radiative forcing caused by rising ozone concentrations in the upper troposphere.

The solar and longwave radiative model developed by Wang et al. (1991) was used for calculating the change in radiative forcing to the troposphere-surface system that can be ascribed to changing concentrations in ozone and other greenhouse gases. Nitric oxide emission from aircraft are a prime suspect for the observed increases in upper tropospheric ozone. The inference can be drawn that a radiative forcing of 0.2 to 0.35 Wm^-2 will result from a doubling of aircraft emissions over the next two decades. This will amount to 10 to 25 percent of the radiative forcing attributable to CO₂ alone for the same period. The effect of doubling aircraft emissions will increase as stratospheric ozone concentrations recover from the recent buildup of harmful chlorofluorocarbons. A large fraction of the radiative forcing that occurred during the 1970 to 1990 period can be attributed to increases in tropospheric ozone as opposed to increases in other greenhouse gases.     

广州市生活垃圾高温有氧静态堆肥的生命周期分析

运用生命周期分析(LCA)方法,对广州市生活垃圾高温有氧静态堆肥系统进行分析,计算出全生命周期的资源消耗和环境影响潜值,同时与垃圾焚烧典型工艺的LCA数据进行对比。结果表明,堆肥处理的环境影响负荷为0.023PET90,资源消耗系数为9.238mPET90。环境影响类型中光化学臭氧合成造成的影响最大,占环境总影响的43.8%。与焚烧处理方式相比,高温有氧静态堆肥的环境总影响较小,环境影响负荷相比于焚烧减少20.3%,在降低酸化的影响方面有较为显著的作用。     

N2O Emissions at Solid Waste Disposal Sites in Osaka City

Nitrous oxide (N₂O) is a trace gas contributing to stratospheric ozone depletion and global warming. Although a large quantity of information exists about N₂O emissions from various ecosystems, this study was initiated to demonstrate the features of N₂O emissions from sea-based waste disposal sites in Osaka City in relation to CH₄ emissions.

Average N₂O emissions at an active landfill (S-Site) were several times higher than those at a closed landfill (N Site). Average CH₄ emissions were also much greater at the S-Site. Regarding the nature of N₂O emissions, remarkable emissions often were observed with aerobic waste layers at the N-Site, suggesting almost inversely related N₂O emissions with CH₄ production at the N-Site. However, at the S-Site a few exceptionally high N₂O emissions were noted in cases of high CH₄ emissions.     

Transport impacts on atmosphere and climate: Shipping

Emissions of exhaust gases and particles from oceangoing ships are a significant and growing contributor to the total emissions from the transportation sector. We present an assessment of the contribution of gaseous and particulate emissions from oceangoing shipping to anthropogenic emissions and air quality. We also assess the degradation in human health and climate change created by these emissions. Regulating ship emissions requires comprehensive knowledge of current fuel consumption and emissions, understanding of their impact on atmospheric composition and climate, and projections of potential future evolutions and mitigation options. Nearly 70% of ship emissions occur within 400 km of coastlines, causing air quality problems through the formation of ground-level ozone, sulphur emissions and particulate matter in coastal areas and harbours with heavy traffic. Furthermore, ozone and aerosol precursor emissions as well as their derivative species from ships may be transported in the atmosphere over several hundreds of kilometres, and thus contribute to air quality problems further inland, even though they are emitted at sea. In addition, ship emissions impact climate. Recent studies indicate that the cooling due to altered clouds far outweighs the warming effects from greenhouse gases such as carbon dioxide (CO₂) or ozone from shipping, overall causing a negative present-day radiative forcing (RF). Current efforts to reduce sulphur and other pollutants from shipping may modify this. However, given the short residence time of sulphate compared to CO₂, the climate response from sulphate is of the order decades while that of CO₂ is centuries. The climatic trade-off between positive and negative radiative forcing is still a topic of scientific research, but from what is currently known, a simple cancellation of global mean forcing components is potentially inappropriate and a more comprehensive assessment metric is required. The CO₂ equivalent emissions using the global temperature change potential (GTP) metric indicate that after 50 years the net global mean effect of current emissions is close to zero through cancellation of warming by CO₂ and cooling by sulphate and nitrogen oxides.     

Sustainable Development by Design: Review of Life Cycle Design and Related Approaches

The environmental profile of goods and services that satisfy our individual and societal needs is shaped by design activities. Substantial evidence suggests that current patterns of human activity on a global scale are not following a sustainable path. Necessary changes to achieve a more sustainable system will require that environmental issues be more effectively addressed in design. But at present much confusion surrounds the incorporation of environmental objectives into the design process. Although not yet fully embraced by industry, the product life cycle system is becoming widely recognized as a useful design framework for understanding the links between societal needs, economic systems and their environmental consequences. The product life cycle encompasses all activities from raw material extraction, manufacturing, and use to final disposal of all residuals.

Life cycle design (LCD), Design for Environment (DFE), and related initiatives based on this product life cycle are emerging as systematic approaches for integrating environmental issues into design. This review presents the life cycle design framework developed forthe U.S. Environmental Protection Agency as a structure for discussing the environmental design literature. Specifying environmental requirements and evaluation metrics are essential elements of designing for sustainable development. A major challenge for successful design is choosing appropriate strategies that satisfy cost, performance, cultural, and legal criteria while also optimizing environmental objectives. Various methods for specifying requirements, strategies for reducing environmental burden, and environmental evaluation tools are explored and critiqued. Currently, many organizational and operational factors limit the applicability of life cycle design and other design approaches to sustainable development. For example, lack of environmental data and simple, effective evaluation tools are major barriers. Despite these problems, companies are beginning to pursue aspects of life cycle design. The future of life cycle design and sustainable development depends on education, government policy and regulations, and industry leadership but fundamental changes in societal values and behavior will ultimately determine the fate of the planet’s life support system.     

Life Cycle Approach to Effective Waste Minimization

In the Hazardous and Solid Waste Amendments of1984, Congress declared the objective of the national waste policy to be "to promote the protection of health and the environment and to conserve valuable material and energy resources." Further, Congress stated that this would be done by minimizing the generation and land disposal of hazardous waste by encouraging process substitutions, materials recovery, proper recycling and reuse, and treatment.

This paper presents the approach used by 3M to find innovative ways to minimize the amount of hazardous waste which ultimately must be disposed by landfilling. The life cycle of waste is examined, looking at how it can be reduced or eliminated starting with the point of generation in the manufacturing operation, to its processing, treatment or ultimate disposal as a residual hazardous waste. Case histories are used as examples of how waste can be minimized in each stage of the life cycle, with emphasis on innovative alternatives that have arisen out of the 3Mprogram.     

The Release of Trichlorofluoromethane from Rigid Polyurethane Foams

The use of trichlorofluoromethane (CCl₃F or F-11) in rigid closed cell polyurethane foams has risen dramatically during the past decade and now constitutes one of the major applications of this fluorocarbon, whereas previously aerosol spray cans consumed most of the production of F-11. Our study shows that F-11 remains in the foams for a very long time, perhaps for a hundred years or more, if the foams remain Intact. While in the past F-11 was released relatively soon after it was produced, now polyurethane insulating foams may constitute a growing reservoir from which F-11 will slowly and persistently leak Into the atmosphere for as long as the foams are in use. Although uncertainties remain, we estimate that in the next 50 years it is probable that as much F-11 will be tied up in foams as in the entire atmosphere at present.