Seasonal changes in the spatial distribution of cellulolytic activity of soil microflora under conditions of atmospheric pollution

Spatial variation in the cellulolytic activity of the soil microflora during the growing season (from May to September) has been studied in spruce-fir forests exposed to emissions from the Middle Ural Copper-Smelting Plant. It has been shown that the average rate of decomposition of pure cellulose in polluted areas is significantly reduced, with its spatial variation being markedly increased. The spatial pattern of cellulolytic activity remains stable during the growing season, and the integrated parameters of frequency distributions in zones with different pollution levels change with time in the same direction.     

高山森林溪流凋落叶冬季水溶性碳含量动态

凋落物分解过程中水溶性碳是高山森林溪流生态系统碳的重要来源,其在溪流中的流动转移不仅会影响下游水质环境,而且其含量动态受冬季季节性雪被形成及消融过程的深刻影响,但缺乏必要关注.因此,采用凋落叶分解袋法,以川西高山森林典型乔木(四川红杉Larix mastersiana、方枝柏Sabina saltuaria)和灌木(高山杜鹃Rhododendron lapponicum、康定柳Salix paraplesia)凋落叶为研究对象,根据凋落叶自然分解规律,研究冬季不同时期(冻结初期、冻结期、融化期)河流、溪流、河岸带以及林下凋落叶水溶性碳以及可溶性组分含量格局的动态变化特征.结果表明:在冬季的分解过程中,冻结初期河流与溪流中凋落叶水溶性碳与可溶性组分含量显著降低,而至冻结期与融化期含量均无明显变化.各时期,林下凋落叶水溶性碳和可溶性组分含量显著高于其他生境,表现为从河流、溪流、河岸带至林下逐渐增加的变化趋势.相关分析表明,高山森林凋落叶分解过程中水溶性碳和可溶性组分含量与平均温度、正积温、负积温以及流速均呈极显著负相关关系,同样也受到PO3-4和p H等水环境因子的影响.可见,高山森林凋落叶冬季水溶性碳和可溶性组分在分解过程中易随水体的流动而向下游生态系统输出,这为深入认识高山森林-流域水体间的生态联系提供了一定的科学依据.     

基于IEEMD样本熵分析的管道泄漏定位

为降低城市管道泄漏定位误差,提出1种改进的集合经验模态分解（IEEMD）样本熵分析的管道多点泄漏定位方法。首先通过在EEMD中添加自相关函数计算和EMD算法,得到IEEMD;然后应用IEEMD可将原始泄漏信号直接去噪并分解为真实信号分量和冗余分量,经样本熵分析计算剔除冗余分量,获得有效泄漏信号;最后根据互相关时延计算和声发射时差定位法精确计算泄漏点位置。结果表明:该方法泄漏信号提取效果好、计算效率更高,有效提高了信号的信噪比,降低了信号的均方误差;该方法将管道泄漏定位误差降低至4.06%,较大程度提高了管道泄漏定位精确度。     

过氧化苯甲酸叔丁酯热危险性实验研究

为了研究TBPB的热危险性,采用液体自燃点测试仪研究TBPB自燃点随浓度的变化规律,应用快速筛选量热仪研究不同升温速率下TBPB的热分解,同时利用差示扫描量热仪研究TBPB热流-温度变化规律。研究结果表明:当TBPB浓度为0.83 g/L时,自燃温度达到最低值125.1 ℃,浓度是影响其自燃温度的重要指标;随升温速率升高,初始分解温度逐渐升高,可见升温速率越高,TBPB分解的初始温度越高,当环境温度未达到初始分解温度时,相对较安全;TBPB最低起始反应温度为95.4 ℃,平均放热量为893.28 J/g,运用Kissinger,Ozawa 这2种方法得出E1=84 063.2 J/mol,E2=86 442.3 J/mol,指前因子为1.69×109,反应级数为0.92。其放热量较大,起始反应温度较低,热量无法及时移出时,极易发生燃烧爆炸事故。     

介质阻挡放电降解异味物质CS_2研究

采用介质阻挡放电降解二硫化碳(CS2)模拟废气,考察了外加气体空气、氮气(N2)、电源输入功率、初始浓度和停留时间对CS2转化率的影响。结果表明:CS2的去除率呈现空气>N2。在输入功率63 W,停留时间为5.34 s,CS2的初始浓度300 mg/m3,N2氛围下的去除效率为36.9%,而空气氛围下的去除效率可达62.5%。在N2与空气氛围下其产物明显不同,在空气氛围下,主要产物为SO2、COS、CO和CO2;而在N2氛围下其主要产物为大量单质硫、少量CO与CO2。对DBD降解CS2的机理分析表明,在N2条件下主要是高能电子与紫外光的作用;而在有空气条件下,O2的存在促进了CS2的深度氧化。     

复合乳化剂对乳化炸药热安全性影响研究

为了探究复合乳化剂对乳化炸药热分解特性的影响,使用C80微量热仪通过MC法研究了乳化剂A(SP80)和乳化剂B(T152)作为单一乳化剂和复合乳化剂(加入比例为1:1、1:2、2:1)制备的乳化炸药。以升温速率为0.5K/min时的C80热流速曲线为基础来求解5种炸药热分解反应的表观活化能(Ea)、指前因子(lnA)等热安全参数。结果表明,使用复合乳化剂制备的乳化炸药稳定性均高于使用单一乳化剂的乳化炸药。采用复合乳化剂可导致乳化剂分子间排斥作用降低,使分子排列更紧密,增加了界面膜的致密性。当加入的乳化剂比例为m(SP80):m(T152)=1:2时,由于两种乳化剂相互作用形成致密的复合界面膜,其稳定性最高。     

有机酸对H发泡剂分解历程的影响及作用机制分析*

为研究有机酸对H发泡剂热分解特性的影响,采用量热仪测试不同质量分数苯甲酸、水杨酸、邻苯二甲酸与H发泡剂混合物的热分解特性参数。结果表明:H发泡剂分解时,随着升温速率增加,外推起始分解温度Te、峰值温度Tp与最大放热速率随之升高。3种有机酸的加入均可以促进H发泡剂的分解,随着有机酸质量分数的增加,其外推起始分解温度和峰值温度呈现同步下降趋势。有机酸熔融生成的H+对H发泡剂分解过程具有显著影响。加入水杨酸能显著降低H发泡剂分解的热释放速率,降低H发泡剂分解过程中的热风险,当水杨酸质量分数达到24%时,较之混有苯甲酸与邻苯二甲酸的H发泡剂外推起始分解温度降低20 ℃。     

Decomposition of forest products buried in landfills

The objective of this study was to investigate the decomposition of selected wood and paper products in landfills. The decomposition of these products under anaerobic landfill conditions results in the generation of biogenic carbon dioxide and methane, while the un-decomposed portion represents a biogenic carbon sink. Information on the decomposition of these municipal waste components is used to estimate national methane emissions inventories, for attribution of carbon storage credits, and to assess the life-cycle greenhouse gas impacts of wood and paper products. Hardwood (HW), softwood (SW), plywood (PW), oriented strand board (OSB), particleboard (PB), medium-density fiberboard (MDF), newsprint (NP), corrugated container (CC) and copy paper (CP) were buried in landfills operated with leachate recirculation, and were excavated after approximately 1.5 and 2.5 yr. Samples were analyzed for cellulose (C), hemicellulose (H), lignin (L), volatile solids (VS), and organic carbon (OC). A holocellulose decomposition index (HOD) and carbon storage factor (CSF) were calculated to evaluate the extent of solids decomposition and carbon storage. Samples of OSB made from HW exhibited cellulose plus hemicellulose (C + H) loss of up to 38%, while loss for the other wood types was 0–10% in most samples. The C + H loss was up to 81%, 95% and 96% for NP, CP and CC, respectively. The CSFs for wood and paper samples ranged from 0.34 to 0.47 and 0.02 to 0.27 g OC g^?1 dry material, respectively. These results, in general, correlated well with an earlier laboratory-scale study, though NP and CC decomposition measured in this study were higher than previously reported.     

Plant matter decomposition in the upper timberline ecotone of the Polar Urals

A relatively high biological activity of soils has been revealed at the upper timberline in the Polar Urals. The role of the altitudinal gradient as a factor of destruction process has distinctly manifested itself upon comparing decomposition rates of flowering plant foliage and herbaceous plant roots in the forest and in the tundra. The qualitative composition of decomposing plant matter has also proved to play a significant role. The soil moisture regime of the ecotope is the leading factor of the destruction process.     

International inequality in CO2 emissions: A new factorial decomposition based on Kaya factors

In this paper, we analyze the determinants of inequality in the global distribution of CO₂ emissions across the regions considered by the International Energy Agency during the period 1990–2010. The inequality analysis is carried out using a factorial decomposition of the second Theil index of inequality. Specifically, based on Kaya factors, CO₂ emissions by active population are decomposed into four factors: carbon intensity of electricity production, electricity intensity of GDP, economic growth in terms of labour productivity and employment rate. The results show that global inequality in CO₂ emissions by active population declined by 22 percent between 1990 and 2010, where the economic growth in terms of labour productivity is the main item responsible for the whole inequality value. Then, a second decomposition by multiplying factors for analyzing the within- and the between-group inequality components is described. In relation to the study of inequality by population groups, it was found that the within-group inequality component had been the main contributor to the whole inequality during all the period. Finally, some economic policy implications are discussed.