广州市工业二氧化碳排放影响因素分析

本文在对广州市工业能源消费和二氧化碳排放研究基础上,通过分析工业总产值、产业结构、社会固定资产投资、能源消费结构、能源利用效率、工业科技投入六个影响因素对工业二氧化碳排放的影响,将我市工业二氧化碳排放影响因素分析最终归结为产业结构、能源消费结构、科技投入三个综合性影响因素,从而提出减少工业二氧化碳排放对策建议。

CO_2对Na_2S脱除SO_2同时制取H_2S过程的影响

冶金和石油行业的SO2与H2S共存脱硫装置———克劳斯装置产生含高浓度SO2的尾气,利用Na2S碱性溶液吸收SO2是一种SCOT法的替代方法。在Na2S碱性溶液吸收SO2过程中,SO2吸收过程为气膜控制,尾气中高浓度的CO2在反应过程中参与化学平衡过程,在一定程度上增加SO2的气相传质阻力,影响SO2的吸收速率,导致反应第二阶段SO2吸收不完全,是放大设计中必须考虑的因素。气相中CO2的存在,有助于提高xH2S/Na2S以及nH2S/SO2,H2S析出更加充分。

Advances in Greenhouse Gases Emission in Farmland Soils

[Objective] The aim was to overview the emission of greenhouse gases in farmland. [Method] Based on domestic and foreign references, production mechanism, discharging characters and major influential factors of CO2, CH4 and N2O in soils of farmland were overviewed. [Result] Production and discharge of CO2, CH. and N2O played an important role in circulation of carbon and nitrogen in terrestrial ecosystem and constituted a key method for carbon and nitrogen output. It is significant to conduct research on reduction of greenhouse gas and increase of absorption. [Conclusion] The research is beneficial for exploration on discharge rule and influential factors of greenhouse gases, providing theoretical references for reduction of greenhouse gases and study on climate change.

Decreasing Arctic Sea Ice Mirrors Increasing CO_2 on Decadal Time Scale

Arctic sea ice is a keystone indicator of greenhouse-gas induced global climate change, which is expected to be amplified in the Arctic. Here we directly compare observed variations in arctic sea-ice extent and CO 2 since the beginning of the 20th century, identifying a strengthening linkage, such that in recent decades the rate of sea-ice decrease mirrors the increase in CO 2 , with r ～ -0.95 over the last four decades, thereby indicating that 90% (r 2 ～ 0.90) of the decreasing sea-ice extent is empirically "accounted for" by the increasing CO 2 in the atmosphere. The author presents an empirical relation between annual sea-ice extent and global atmospheric CO 2 concentrations, in which sea-ice reductions are linearly, inversely proportional to the magnitude of increase of CO 2 over the last few decades. This approximates sea-ice changes during the most recent four decades, with a proportionality constant of 0.030 million km 2 per ppmv CO 2 . When applied to future emission scenarios of the Intergovernmental Panel on Climate Change (IPCC), this relationship results in substantially faster ice decreases up to 2050 than predicted by IPCC models. However, departures from this projection may arise from non-linear feedback effects and/or temporary natural variations on interannual timescales, such as the record minimum of sea-ice extent observed in September 2007.

The spatial distribution of commuting CO_2 emissions and the influential factors:A case study in Xi'an,China

As the transport sector is a major source of greenhouse gas emissions, the effect of urbanization on transport CO2 emissions in developing cities has become a key issue under global climate change. Examining the case of Xi＇an, this paper aims to explore the spatial distribution of commuting CO2 emissions and influencing factors in the new, urban industry zones and city centers considering Xi＇an＇s transition from a monocentric to a polycentric city in the process of urbanization. Based on household survey data from 1501 respondents, there are obvious differences in commuting CO2 emissions between new industry zones and city centers： City centers feature lower household emissions of 2.86 kg CO2 per week, whereas new industry zones generally have higher household emissions of 3.20 kg CO2 per week. Contrary to previous research results, not all new industry zones have high levels of CO2 emissions; with the rapid development of various types of industries, even a minimum level of household emissions of 2.53 kg CO2 per week is possible. The uneven distribution of commuting CO2 emissions is not uniformly affected by spatial parameters such as job-housing balance, residential density, employment density, and land use diversity. Optimum combination of the spatial parameters and travel pattern along with corresponding transport infrastructure construction may be an appropriate path to reduction and control of emissions from commuting.

High-efficiency acetaldehyde removal during solid-state polycondensation of poly(ethylene terephthalate) assisted by supercritical carbon dioxide

The concentration of acetaldehyde(AA) is the main quality index of poly(ethylene terephthalate)(PET) used in food and drink packaging.A new method for AA removal has been developed by using supercritical carbon dioxide(sc CO2) during the solid-state polycondensation of PET.The influence factors of AA removal including the temperature,pressure,reaction time and the size of pre-polymer particles are systematically studied in this work.The results indicate that it is a highly efficient way to obtain high molecular weight PET with relative low concentration of AA.Correspondingly,the polymerization degree of PET could increase from 27.9 to 85.6 while the concentration of AA reduces from 0.229 × 10^(-6) to 0.055 × 10^(-6) under the optimal operation conditions of 230 °C,8 MPa and size of 0.30–0.45 mm.Thermodynamic performance tests show the increasing extent of PET crystallinity due to the fact that the plasticization of sc CO_2 is not obvious with extended reaction time,therefore the increasing crystallinity has no significant influence on AA removal.SEM observations reveal that the effects of sc CO_(2-) induced plasticization and swelling on PET increase significantly with the decrease of prepolymer size,and the surface of PET becomes more loose and porous in favor of the AA removal.

Environmental life cycle assessment of Indian coal-fired power plants

Coal is the backbone of the Indian power sector. The coal-fired power plants remain the largest emitters of carbon dioxide, sulfur dioxide and substantial amounts of nitrogen oxides, which are associated with climate and health impacts. Various CO2 mitigation technologies （carbon capture and storage--CCS） and SO2/NOx mitigation technologies （flue gas desulfurization and selective catalytic reduction） have been employed to reduce the environmental impacts of the coal-fired power plants. Therefore, it is imperative to understand the feasibility of various mitigation technologies employed. This paper attempts to perform environmental life cycle assessment （LCA） of Indian coal-fired power plant with and without CO2, SO2 and NOx mitigation controls. The study develops new normalization factors for India in various damage categories, using the Indian emissions and energy consumption data, coupled with the emissions and particulate emission to come up with a final environmental impact of coal-fired electricity. The results show a large degree of dependence on the perspective of assessment used. The impact of sensitivities of individual substances and the effect of plant efficiency on the final LCA results is also studied.

Investigations of Carbon Sequestration and Storage Using Advanced Geospatial Analysis

This research demonstrated quantitative methods of geospatial analysis applicable to carbon sequestration and storage in the conterminous United Sates. We identified national-scale NEP （net ecosystem production） changes for conversions to and from crop, and land in frequent conversion among forest, wetland, pasture and rangeland. The trend showed an increase in the margins of the Corn Belt states and coincided with land conversion from previous non-cropland to cropland in the United States. This research will not only improve the engineering understanding of carbon dioxide removal options involving the terrestrial biosphere, but will also inform decision-making in the carbon emission impacts. Therefore, it will provide a spatio-temporal reference for analyzing the national-level carbon exchange systems in the United States.

Application of Biochars for Soil Constraints:Challenges and Solutions

Biochar addition to soil is currently being considered as a means to sequester carbon while simultaneously improving soil health,soil fertility and agronomic benefits. The focus of this special issue is on current research on the effects of biochar application to soil for overcoming diverse soil constraints and recommending further research relating to biochar application to soil. The biochar research has progressed considerably with important key findings on agronomic benefits, carbon sequestration, greenhouse gas emissions, soil acidity, soil fertility, soil health, soil salinity, etc., but more research is required before definitive recommendations can be made to end-users regarding the effects of biochar application across a range of soils, climates and land management practices.