云南香格里拉本底站大气CH4体积分数及变化特征

利用基于光腔衰荡光谱(CRDS)技术自组装的大气CH4在线观测系统,于2010年7月—2011年10月在云南香格里拉大气本底站对大气CH4进行了在线观测.结果发现,该站春、夏、秋、冬季CH4平均本底值分别为(1850.7±6.9)×10-9(体积分数,下同)、(1850.9±13.4)×10-9、(1865.6±16.1)×10-9和(1839.2±6.5)×10-9.全年体积分数在9月最高,12月最低,月均值振幅约39.6×10-9.4季日平均最低值均出现在14:00—16:00.日变化振幅在冬季最小,秋季最大,分别为4.4×10-9和10.0×10-9.西南来向的地面风会明显抬升CH4体积分数,而北偏东来向的地面风显著降低观测结果.通过4季每日整点后向轨迹聚类计算,结合观测资料分析发现,该站CH4主要受西南来向气团传输影响,尤其在春、夏、秋3季.     

Effect of Prescribed Fire on Soil Properties and N Transformation in Two Vegetation Types in South China

Prescribed fire is a common site preparation practice in forest management in southern China. However, the effect of fire on soil properties and N transformations is still poorly understood in this region. In this study, soil properties and N transformations in burned and unburned site of two vegetation types (Eucalyptus plantation and shrubland) were compared in rainy and dry seasons after 2 years’ prescribed fire. Soil pH and soil NH₄-N were all higher in the burned site compared to the unburned control. Furthermore, burned sites had 30–40 % lower of soil total phosphorus than conspecific unburned sites. There was no difference in soil organic matter, total N, soil exchangeable cations, available P or NO₃-N. Nitrogen mineralization rate of 0–5 cm soil in the unburned site ranged from 8.24 to 11.6 mg N kg^?1 soil month^?1 in the rainy season, compared to a lower level of 4.82–5.25 mg N kg^?1 soil month^?1 in the burned sites. In contrast, 0–5 cm layer nitrification rate was overall 2.47 mg N kg^?1 soil month^?1 in the rainy season, and was not significantly affected by burning. The reduced understory vegetation coverage after burning may be responsible for the higher soil NH₄-N in the burned site. This study highlights that a better understanding the effect of prescribed burning on soil nutrients cycling would provide a critical foundation for management decision and be beneficial to afforestation in southern China.     

Synthesis and Characterization of Biodegradable Starch-Polyacrylamide Graft Copolymers Using Starches with Different Microstructures

The effects of starch structures, in particular amylose content, on grafting reactions were investigated using thermal gravimetric analysis (TGA), nuclear magnetic resonance, X-ray diffraction (XRD). As a model system, corn starches with different amylose contents (0, 26, 50 and 80 %) were grafted onto acrylamide to produce superabsorbent polymers (SAPs). The weight loss measured by TGA at different temperature was used to analyze the grafting ratio in quantity. In general, the grafting ratio increased (about 10 %) with increasing starch amylose content, and graft chain segment lengths were much lower for the amylopectin-rich (waxy) starch. The high molecular weight and branched structure of the amylopectin reduced the mobility of the polymer chains and increased viscosity, which resulted in resistance to chain growth. The water absorption capability was increased with increasing amylose content for the starch-based SAPs. XRD detection showed that the crystalline structure of all starches was destroyed after grafting reactions. The thermal stability of the polyacrylamide grafted onto the starches increased by about 10 °C, which could be explained by the strong bonding between the grafted polymer chains and the starch matrices.     

氧化偶氮胂M褪色光度法测定微量锰的研究

在酸性介质中,Ｍｎ（Ⅶ）强的氧化性对偶氮胂Ｍ有褪色作用,借此进行吸光光度法测定微量锰的研究。实验表明,在１８～２７ｍｏｌ／ＬＨ２ＳＯ４介质中,有色溶液的最大吸收波长为５４０ｎｍ,表观摩尔吸光系数为１８３×１０４Ｌ／ｍｏｌ·ｃｍ,锰量在０～１４μｇ／ｍｌ范围内与有色溶液吸光度的减少值呈线性关系。方法简单快速、选择性好、准确度高,灵敏度是高锰酸盐法的近８倍,可用于测定水样、地质样品中的微量锰。在测定某些地质样品中的微量锰时,结果满意。     

城市生活垃圾并流竖炉焚烧模拟实验研究

气化熔融焚烧技术能够避免重金属和二恶英的二次污染,被公认为实现零排放和环境友好型的焚烧方法。在这样的背景下提出了生活垃圾并流竖炉气化熔融焚烧工艺。该工艺以竖炉为气化熔融主体设备,垃圾料层与助燃空气在炉内都是至上而下并流流动,从而使垃圾热解气化产生的可燃气体在竖炉下部完全燃烧,以提供灰渣熔融耗热。并流竖炉热态模拟试验表明,并流时垃圾料层中各点的温度明显高于逆流情况,并流时产生的CO₂量明显高于逆流情况。因此说并流竖炉更适合气化熔融焚烧工艺的要求。     

Trapping and decomposing of color compounds from recycled water by TiO2 coated activated carbon

Five types of commercially available activated carbons (ACs) were coated with TiO₂ nanoparticles prepared using a sol–gel method. Color and trace organics remaining in the actual treated effluent were adsorbed by TiO₂ coated ACs. The absorbed organic compounds were then decomposed using a photocatalytic process, and the ACs were regenerated for reuse. The efficiency of the process was assessed by the characterization of true color and A₂₅₄ (the organics absorption at the wavelength of 254 nm) at the beginning and the end of the experiment. The effects of UV light source, UV irradiation time, hydrogen peroxide and ultrasound on the efficiency of photocatalytic regeneration were also investigated. Significant differences in the efficiency were observed between uncoated ACs and TiO₂ coated samples. Among the 5 types of ACs tested, AC-3, AC-4 and their coated ones achieved better efficiency in color and A₂₅₄ removal, with around 90% or more color and A₂₅₄ being removed within 1 h of treatment. The data obtained in this study also demonstrated that the photocatalytic process was effective for decomposing the adsorbed compounds and regenerating the spent TiO₂/AC-3. Finally, it was found that this regeneration process could be greatly enhanced with the assistance of H₂O₂ and ultrasound by reducing the required regeneration time.     

冬季沈阳市典型源排放PM_(10)浓度分布模拟分析

选取沈阳市7个典型的大气污染源2006年12月~2007年2月的PM10排放浓度资料,利用CALPUFF对PM10浓度月平均分布做模拟分析。模拟结果分析表明:冬季月平均PM10浓度分布的范围与风场、地形有直接的关系。地势平坦、风速大时,污染物扩散范围大,污染物浓度小;地势不平、风速小时,污染物扩散范围小,污染物浓度大。1月份是沈阳市冬季月平均大气污染最严重的月份,污染物分布主要集中在市区的北部、东部和南部地区,东部地区大气污染最为严重。     

Economic Valuation of Health Impact of PM10 Pollution in Beijing from 2001 to 2006

In light of the practical need for research to inform policy in Beijing,this study evaluates the economic cost of the impact of PM10 pollution in Beijing from 2001 to 2006,taking health as the main impact,and mortality as the main outcome.Based on the literature review,this study adopts relatively conservative parameters as the basis for calculating the health impacts.It concludes that nearly 30% of mortality among registered residents above age 30 in Beijing can be attributed to PM10 pollution,and that the economic cost equals 0.8%-1.2% of the city's GDP over the same period.This is lower than the results of previous studies,but still high enough to warrant a commitment to solve the city's air pollution problem.     

沸腾炉大气污染物的生成与排放特征分析

以20台沸腾炉(功率小于等于60 MW)的燃料特性分析数据和大气污染物的排放实测数据为基础,利用统计分析方法,研究了燃烧过程中排放的颗粒物(PM)、SO_2和NO_x初始排放浓度的影响因素,分析了沸腾炉PM、SO_2和NO_x排放现状,探讨了我国中小型沸腾炉PM、SO_2和NO_x排放管理控制的潜力和可行性.实验结果表明:在锅炉运行负荷大于等于80%的条件下,中小型沸腾炉PM的初始排放浓度基本上不受锅炉出力、过量空气系数和燃煤灰分含量的影响;燃煤的硫含量越高,SO_2初始排放浓度越高;过量空气系数越大,燃煤挥发分越低,NO_x初始排放浓度越高.