Emission of CO2, CH4 and N2O from freshwater marsh in northeast of China

The wetlands play an important role in carbon storage, especially at high latitudes, at which they store nearly one-third of global soil carbons. However, few studies have investigated the emissions of CO(2), CH(4) and N(2)O in the long-term, especially effects of freeze-thaw cycles on these gases emissions in freshwater marsh ecosystems. In this paper, we collected greenhouse gas emission data from a freshwater marsh area in China for 4 years, evaluated their release variables and speculated on their potential atmospheric impact. For this paper, we report on the CO(2), CH(4) and N(2)O emission rates recorded from June 2002 to November 2005 in the Sanjiang Plain of northeast China. We measured their interannual variations and fluctuations, as well as factors affecting their emissions, and estimated their regulation and freeze-thaw cycle impacts. Our results revealed obvious CO(2) and CH(4) emission fluctuations during the winter months, and during the freeze-thaw cycle, and a strong interannual variation during the growing season. Overall, we documented a close relationship between the CO(2) and CH(4) emissions, implicating some regulatory commonality. We determined that the marsh was a N(2)O sink during the winter, but a significant source of N(2)O during the freeze-thaw cycle as the temperature increased, especially in early summer. During the thaw-freeze period, the N(2)O levels were positively correlated with the water depth. Additionally, water depth greatly governed the interannual variation of the N(2)O emissions from the marshes during the thaw-freeze period.     

水稻土中半胱氨酸分解产生含硫气体的研究

在室内培养条件下,测定了水稻土中含硫气体的释放．结果表明,该土壤中有硫化氢(Ｈ２Ｓ),羰基硫(ＣＯＳ),二甲基硫(ＤＭＳ)三种气体释放．当土壤中加入半胱氨酸后,ＣＯＳ和Ｈ２Ｓ气体的浓度有了明显增加,并有ＣＳ２和ＣＨ３ＳＨ测出,而ＤＭＳ的浓度变化不大．这些结果表明半胱氨酸的分解可能是 ＣＯＳ,Ｈ２Ｓ,ＣＳ２和 ＣＨ３ＳＨ的产生源之一．在好氧(正常大气)条件下,Ｈ２Ｓ,ＣＯＳ,ＣＳ２和ＣＨ３ＳＨ的释放量低于厌氧(氮气氛围)条件下的释放量,ＤＭＳ则高于厌氧条件下．这表明水稻土中半胱氨酸分解产生 Ｈ２Ｓ,ＣＯＳ,ＣＳ２和 ＣＨ３ＳＨ需较强的还原条件,产生这四种气体的微生物需要严格的厌氧条件．产生ＤＭＳ的微生物则比前者需要高一些的含氧量．在光照条件下,各含硫气体的释放量普遍高于无光照条件下的释放量．释放含硫气体的大多数微生物适宜的含水率为５０%且对土壤的ｐＨ值有一定要求．     

太湖零点行动前后水质状况对比分析

根据 1 998年 1 1月和 1 999年 1 0月的监测数据 ,对零点行动前后太湖各监测点位的水质状况及DO、CODMn、TP、TN、Chla等主要指标的空间分布进行了对比 ,发现污染状况并未得到明显改善 ,除了人为因素外 ,非点源污染的贡献和底泥营养物质的释放是影响水质改善的 2个重要因素     

Determination of PCDDs,PCDFs, PCBs and HCB emissions from the metallurgical sector in Poland

Background The aim of the project was to measure the actual emissions of PCDD/F, PCBs and HCB from 20 selected metallurgical installations in Poland, in order to update the national inventory of dioxin emission from metallurgical industry for developing a strategy for dioxins and furans emission abatement from the subject facilities (UNEP 2005). Methods Sampling methodology used in this work was developed at the Cracow University of Technology because of the complexity of simultaneous sampling and determining PCDFs, PCDDs, PCB and HCB. For the determination a GC-MS/MS system was used. Results and Discussion Results from the work indicate that the highest dioxins and PCB concentrations were recorded for iron ore sintering plants at 1.10–1.32 ng total¹ TEQ/Nm³ followed by aluminium scrap melting at 0.03–0.66 ng total TEQ/Nm³. The highest HCB concentrations at 613–1491 ng/Nm³ were also recorded for iron ore sintering plants, whereas at aluminium plants the HCB concentrations were in the range of only 10.1–22.7 ng/Nm³. Conclusions The above investigations indicate that secondary aluminium production is the most significant dioxins source, if calculated as emission factor values. However, iron ore sintering plants are operating at much higher production capacity, causing this process to become the major source of dioxins, PCB and HCB pollution to the atmosphere in Poland. Recommendations and Perspectives Based on the performed tests and the environmental reviews of selected plants several recommendations were formulated for the reduction of generation or of emission of these pollutants from iron ore sintering plants, electric arc furnace steel production processes, hot-blast furnace operations, secondary aluminium smelting and primary zinc production from zinc cathodes.     

交叉口机动车尾气污染扩散模型综述

文章介绍了美国主要的交叉口尾气污染扩散模型,并对模型进行了比较评价,探讨了传统交叉口扩散模型的缺陷;介绍了国内外交叉口尾气扩散研究的最新发展动态,最后提出了提高模型精度和发展新模型的几点建议。     

广西重点行业二氧化碳减排潜力分析

为加快CDM项目的开发,以广西为试点,采用自下而上的方法针对其重点行业的二氧化碳减排潜力进行评价,具体地包括:高耗能工业(冶金、有色金属、建材、化工、制糖、造纸等)、电力(火电、水电、风电)、户用沼气池、木薯制燃料酒精、有机废液利用等。结果表明到2010年广西上述领域的碳减排潜力(以碳计)可达1623万t。为促进广西的可持续发展,不仅应在水电、风电、提高能效等已有方法学的领域积极开展CDM项目,还应加强其它领域如木薯制燃料酒精、户用沼气池等CDM方法学以及CDM项目的开发。     

速度场常数及其自动检测装置

通过对烟道“速度场常数”的研究,提出利用速度场常数监测烟道烟气平均流速的方法,同时研制出速度场常数自动检测装置。解决烟道烟气平均流速自动监测的技术难题。     

生物柴油发动机颗粒排放物粒径及其分布试验研究

为获取燃用不同比例生物柴油的发动机排放颗粒物粒径及其分布特性,对1台增压直喷式车用柴油机进行了台架测试.用80 L/min定量泵和装有直径90 mm的玻纤滤膜采样器在排气管内采样10 min,用激光粒度仪测量与分析颗粒粒径和分布.结果表明,随着发动机转速提高,排放颗粒粒径变小且分布更集中.干法众数对应的粒径级较大（约10～12 μm）且较集中,湿法众数的较小（约4～10 μm）且分散.用干法分析,发动机低速时,B100的Sauter平均直径d₃₂最大,纯柴油最小,而B20的结果介于二者之间.而高速时B20的粒径最大,纯柴油次之,B100最小.中数粒径d(0.5)的结果也反映这一趋势.用湿法分析,除了2?000 r/min点外, B20的d₃₂最大,B100次之,柴油最小.湿法众数比干法分散,因而d₃₂也较大.     

Relationships of nitrous oxide fluxes with water quality parameters in free water surface constructed wetlands

The effects of chemical oxygen demand (COD) concentration in the influent on nitrous oxide (N₂O) emissions, together with the relationships between N₂O and water quality parameters in free water surface constructed wetlands, were investigated with laboratoryscale systems. N₂O emission and purification performance of wastewater were very strongly dependent on COD concentration in the influent, and the total N₂O emission in the system with middle COD influent concentration was the least. The relationships between N₂O and the chemical and physical water quality variables were studied by using principal component scores in multiple linear regression analysis to predict N₂O flux. The multiple linear regression model against principal components indicated that different water parameters affected N₂O flux with different COD concentrations in the influent, but nitrate nitrogen affected N₂O flux in all systems.     

我国“十二五”期间推进清洁生产工作的思考

在末端治理日臻完善的时代,清洁生产是人类污染治理方式和生产力发展方式上的一次革命。我国推行清洁生产已有10余年,但进展较缓慢。本文在阐释清洁生产内涵的基础上分析了我国在推行清洁生产过程中存在的部分问题及其原因,提出了相应的对策和建议。