Emission inventory of deca-brominated diphenyl ether (DBDE) in Japan

Atmospheric emissions of deca-brominated diphenyl ether (DBDE) in Japan were estimated based on the material flow of DBDE products and their emission factors. In 2002, the demand for DBDE in Japan was 2200 ton/year and the stock level was about 60 000 ton. The DBDE flow into the waste stream was estimated to be about 6000 ton/year and the flow out through second-hand product exports was more than 700 ton/year. Home appliance recycling facilities dismantle and crush domestic wastes containing about 600 ton of DBDE annually. Material recycling of crushed plastics is not commonly practiced as yet. Emission factors from plastics processing (2 × 10⁻⁹–1 × 10⁻⁷), textile processing (9 × 10⁻⁷), home appliance recycling (8 × 10⁻⁹–5 × 10⁻⁶), and waste incineration (1 × 10⁻⁷–2 × 10⁻⁶) were estimated using field measurement data. The DBDE emission rate through house dust during the service life of final products (2 × 10⁻⁷–9 × 10⁻⁷ per year) was estimated using the DBDE concentration in dust and the amount of dust in used televisions. Emission factors from previous studies were also used. The estimated total DBDE emission was 170–1800 kg/year. These results suggest the necessity of characterizing emissions during the service life of products, which is essential information for formulating an appropriate e-waste recycling strategy.     

Environmental sub models for a macroeconomic model: agricultural contribution to climate change and acidification in Denmark

Integrated modelling of the interaction between environmental pressure and economic development is a useful tool to evaluate environmental consequences of policy initiatives. However, the usefulness of such models is often restricted by the fact that these models only include a limited set of environmental impacts, which are often energy-related emissions. In order to evaluate the development in the overall environmental pressure correctly, these model systems must be extended. In this article an integrated macroeconomic model system of the Danish economy with environmental modules of energy related emissions is extended to include the agricultural contribution to climate change and acidification. Next to the energy sector, the agricultural sector is the most important contributor to these environmental themes and subsequently the extended model complex calculates more than 99% of the contribution to both climate change and acidification. Environmental sub-models are developed for agriculture-related emissions of CH(4), N(2)O and NH(3). Agricultural emission sources related to the production specific activity variables are mapped and emission dependent parameters are identified in order to calculate emission coefficients. The emission coefficients are linked to the economic activity variables of the Danish agricultural production. The model system is demonstrated by projections of agriculture-related emissions in Denmark under two alternative sets of assumptions: a baseline projection of the general economic development and a policy scenario for changes in the husbandry sector within the agricultural sector.     

Polychlorinated dibenzo-p-dioxins and dibenzofurans emissions from open burning of crop residues in China between 1997 and 2004

Annual emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from open burning of crop residues in each province of China mainland between 1997 and 2004 were estimated to be ranged from 1.38x10(3) to 1.52x10(3) g I-TEQ/yr, with the average of 1.50+/-0.08x10(3) g I-TEQ/yr, which contributed to approximately 10% approximately 20% of the total emissions in China. The PCDD/F emissions mainly occurred in the largest crop-producing provinces, especially in those of higher economic levels. The major sources of PCDD/F emissions from open burning in China were found to be cereal residues (i.e. rice, wheat, and corn), which accounted about 70% of the total emissions. Moreover, the first-order one-variable grey differential equation model (GM (1,1) model) for annual emissions of PCDD/Fs was established based on grey system theory. The GM (1,1) model was proved to be robust to predict the annual PCDD/F emissions from crop residue field burning in forthcoming years.     

Real-world emission characteristics of carbonyl compounds from agricultural machines based on a portable emission measurement system

Emissions of carbonyl compounds from agricultural machines cannot be ignored. Carbonyl compounds can cause the formation of ozone (O₃) and secondary organic aerosols, which can cause photochemical smog to form. In this study, 20 agricultural machines were tested using portable emission measurement system (PEMS) under real-world tillage processes. The exhaust gases were sampled using 2,4-dinitrophenylhydrazine cartridges, and 15 carbonyl compounds were analyzed by high-performance liquid chromatography. Carbonyl compound emission factors for agricultural machines were 51.14–3315.62 mg/(kg-fuel), and were 2.58 ± 2.05, 0.86 ± 1.07 and 0.29 ± 0.20 g/(kg-fuel) for China 0, China II and China III emission standards, respectively. Carbonyl compound emission factor for sowing seeds of China 0 agricultural machines was 3.32 ± 1.73 g/(kg-fuel). Formaldehyde, acetaldehyde and acrolein were the dominant carbonyl compounds emitted. Differences in emission standards and tillage processes impact ozone formation potential (OFP). The mean OFP was 20.15 ± 16.15 g O₃/(kg-fuel) for the China 0 emission standard. The OFP values decreased by 66.9% from China 0 to China II, and 67.4% from China II to China III. The mean OFP for sowing seeds of China 0 agricultural machines was 25.92 ± 13.84 g O₃/(kg-fuel). Between 1.75 and 24.22 times more ozone was found to be formed during sowing seeds than during other processes for China 0 and China II agricultural machines. Total carbonyl compound emissions from agricultural machines in China was 19.23 Gg in 2019. The results improve our understanding of carbonyl compound emissions from agricultural machines in China.     

红壤剖面重金属分布特征及对有机碳响应

以湖南株洲红壤耕地剖面土(0~100 cm)为样本,对剖面全土及胶体中重金属的纵向分布特征,重金属的来源和相关性进行了分析,并探究剖面土壤中重金属分布对有机碳组成的响应.剖面土中重金属含量依次为ZnCrCuPbNiAsCd,其中Cd在各个剖面中都属重度污染,Zn在部分剖面中是轻度污染,其它金属都在尚清洁区域.主成分分析表明,剖面金属分布分为两大主成分,第一主成分金属为Zn、Cu、Pb、As、Cd;第二主成分金属为Cr和Ni,主成分元素之间具有较强的正相关关系.在0~30 cm耕作区,第一主成分金属随剖面向下,含量逐渐减小;第二主成分金属随剖面向下,含量增大.对不同尺度颗粒组研究发现,As、Cu、Zn、Cd、Cr、Ni以胶体形式在土壤中进行纵向迁移;而Pb主要以向53μm的黏粒组分富集为主,其胶体携带作用不显著.红外光谱分析表明,土壤中有机碳以多糖类(22.07%~47.13%)、芳香类(13.88%~34.37%)和醇类(21.04%~59.49%)为主.其中,稳定性有机碳,即多糖类和芳香类碳有利于第一主成分金属在土壤中的吸附固定,使其不易向深层迁移;而活性醇碳则能促进第一主成分金属的迁移.     

Advances in emission control of diesel vehicles in China

Diesel vehicles have caused serious environmental problems in China. Hence, the Chinese government has launched serious actions against air pollution and imposed more stringent regulations on diesel vehicle emissions in the latest China VI standard. To fulfill this stringent legislation, two major technical routes, including the exhaust gas recirculation (EGR) and high-efficiency selective catalytic reduction (SCR) routes, have been developed for diesel engines. Moreover, complicated aftertreatment technologies have also been developed, including use of a diesel oxidation catalyst (DOC) for controlling carbon monoxide (CO) and hydrocarbon (HC) emissions, diesel particulate filter (DPF) for particle mass (PM) emission control, SCR for the control of NOx emission, and an ammonia slip catalyst (ASC) for the control of unreacted NH₃. Due to the stringent requirements of the China VI standard, the aftertreatment system needs to be more deeply integrated with the engine system. In the future, aftertreatment technologies will need further upgrades to fulfill the requirements of the near-zero emission target for diesel vehicles.     

Quantification of emission reduction potentials of primary air pollutants from residential solid fuel combustion by adopting cleaner fuels in China

Residential low efficient fuel burning is a major source of many air pollutants produced during incomplete combustions, and household air pollution has been identified as one of the top environmental risk factors. Here we compiled literature-reported emission factors of pollutants including carbon monoxide(CO), total suspended particles(TSPs), PM2.5, organic carbon(OC),elemental carbon(EC) and polycyclic aromatic hydrocarbons(PAHs) for different household energy sources, and quantified the potential for emission reduction by clean fuel adoption. The burning of crop straws, firewood and coal chunks in residential stoves had high emissions per unit fuel mass but lower thermal efficiencies, resulting in high levels of pollution emissions per unit of useful energy, whereas pelletized biofuels and coal briquettes had lower pollutant emissions and higher thermal efficiencies. Briquetting coal may lead to 82%–88% CO, 74%–99%TSP, 73%–76% PM2.5, 64%–98% OC, 92%–99% EC and 80%–83% PAH reductions compared to raw chunk coal. Biomass pelletizing technology would achieve 88%–97% CO, 73%–87% TSP, 79%–88%PM2.5, 94%–96% OC, 91%–99% EC and 63%–96% PAH reduction compared to biomass burning. The adoption of gas fuels(i.e., liquid petroleum gas, natural gas) would achieve significant pollutant reduction, nearly 96% for targeted pollutants. The reduction is related not only to fuel change, but also to the usage of high efficiency stoves.     

Review on fate of chlorine during thermal processing of solid wastes

Chlorine(Cl) is extensively present in solid wastes, causing significant problems during the thermal conversion of waste to energy or fuels, by combustion, gasification or pyrolysis.This paper introduces the analytical methods for determining the Cl content in solid materials and presents the concentrations of Cl in various types of wastes, as reported in literature. Then, it provides a comprehensive analysis on the Cl emission behavior and Cl species formed during the thermal processing of the inorganic and organic Cl sources. The challenges resulted from the reactions between the formed Cl species and the ferrous metals, the heavy metals and the organic matters are summarized and discussed, e.g., high temperature corrosion, heavy metal evaporation and dioxin formation. The quality degradation of products(oil, char and syngas) by Cl is analyzed. Finally, the available controlling methods of Cl emission, including pre-treatment(water washing, sorting,microwave irradiation and stepwise pyrolysis) and in-furnace(absorbents, co-treatment and catalysts) methods are assessed.     

反应堆压力容器材料中Ni界面偏析对富Cu溶质团簇演化影响的模拟研究

目的定量研究镍原子的界面偏析对降低团簇与基体间表面能及促进团簇形核、提升团簇数密度的贡献,以深化对反应堆压力容器溶质团簇演化过程和辐照脆化中溶质团簇机理的认识。方法通过考虑Fe-Cu-Ni三元合金溶质团簇中镍原子的界面偏析,利用团簇动力学方法研究了团簇中镍原子分布对富铜溶质团簇演化的影响。结果相比铜团簇,加入镍原子后的铜镍团簇自由能显著降低,团簇数密度显著提高;随团簇中镍原子界面偏析加剧,团簇自由能与团簇尺寸逐渐下降,团簇数密度先小幅上升,后下降。结论镍可以促进富铜溶质团簇的形核,提升团簇的数密度,而其中镍原子的界面偏析对促进团簇形核的贡献可能有限;在团簇生长过程中,镍原子的界面偏析可能会抑制其生长,减小团簇的尺寸。     

土地利用方式对土壤有机质及其碳库管理指数的影响

采用野外调查和室内分析的方式对子午岭不同土地利用方式下,土壤有机质、3种活性有机质及其碳库管理指数(CMI)进行了研究,结果表明,土壤有机质、3种活性土壤有机质含量均随土层的加深逐渐降低,在土壤剖面基本表现为林地、撂荒未翻耕地>撂荒翻耕地>农用地.同一土层,3种土壤活性有机质含量及其有效率表现为低活性有机质>中活性有机质>高活性有机质.不同利用方式下,活性有机质有效率随有机质活性增强,呈现撂荒未翻耕地>林地>撂荒翻耕地>农用地的趋势.不同利用方式之间的CMI的差异随有机质活性的增强而增大,且影响深度也逐渐加深.在0~30cm土层内,林地3种活性有机质的CMI高于撂荒翻耕地和农用地;而在30cm之下土层,3种利用方式低活性有机质的CMI相差不大,但中活性有机质和高活性有机质的CMI表现为林地>撂荒翻耕地>农用地.3种活性土壤有机质与其他生物化学性质之间均表现为显著或极显著相关关系,表明活性有机质可以指示土地利用方式对土壤有机质和CMI的影响.