草地退化对三江源区高寒草甸生态系统CO2通量的影响及其原因

为了揭示草地退化对三江源地区高寒草甸生态系统碳通量的影响,利用涡度相关技术,于2006年12月1日~2007年11月30日对三江源地区的退化高寒草甸生态系统的碳通量及生物和环境因子进行观测.结果发现:草地退化对高寒草甸生态系统的碳通量产生了深刻影响,与未退化的高寒草甸生态系统相比,退化高寒草甸生态系统全年总初级生产力(GPP)下降了36.6%,全年生态系统呼吸(Reco)下降了7.9%,全年净生态系统CO2交换(NEE)也由退化前的负值(碳吸收)转变为正值(碳排放),二者相差132.5gC/(m2·a),生态系统由原来的碳汇转变为目前的碳源.这些变化与高寒草甸退化后,生态系统植物地上生物量锐减、植物生长期缩短(NEE<0的天数)、植物多样性下降、土壤含水量降低等因素密切相关.     

贵州喀斯特地区不同土地利用方式土壤CO_2体积分数变化及影响因素

为了解不同土地利用方式对土壤剖面CO2体积分数的影响,采用气相色谱法对贵州喀斯特地区土壤不同深度空气CO2体积分数进行观测。结果表明：不同土地利用对土壤平均CO2体积分数影响较大,其次序为：次生林（0.35%±0.06%）〉草地（0.34%±0.05%）〉人工林（0.27%±0.03%）〉农田（0.16%±0.03%）。次生林、草地与农田之间土壤CO2体积分数差异性显著,而人工林与农田之间无显著性差异。不同土地利用方式土壤剖面CO2体积分数的时空变化特征比较一致：从春季到夏季逐渐增加而从秋季到冬季又逐渐降低,与该区域的温度和降雨量变化趋势一致。同时随着土壤剖面深度增加CO2体积分数逐渐增大,但在土层12 cm处有突然降低现象（农田除外）。不同土地利用方式土壤空气CO2体积分数变化与大气、土壤温度密切相关（r=0.602~0.886,P〈0.05）,土壤温度升高会导致土壤CO2体积分数上升。土壤湿度虽然也在一定程度上影响了剖面CO2体积分数,但相关性分析表明二者之间并不显著（r=0.105~0.393,P〉0.05）,说明在贵州喀斯特地区,土壤温度对土壤空气CO2体积分数的影响大于土壤湿度。     

Elevated CO2 facilitates C and N accumulation in a rice paddy ecosystem

Elevated CO2 can stimulate wetland carbon(C) and nitrogen(N) exports through gaseous and dissolved pathways, however, the consequent influences on the C and N pools are still not fully known. Therefore, we set up a free-air CO2 enrichment experiment in a paddy field in Eastern China. After five year fumigation, we studied C and N in the plant–water–soil system. The results showed:(1) elevated CO2 stimulated rice aboveground biomass and N accumulations by 19.1% and 12.5%, respectively.(2) Elevated CO2 significantly increased paddy soil TOC and TN contents by 12.5% and 15.5%, respectively in the 0–15 cm layer, and22.7% and 26.0% in the 15–30 cm soil layer.(3) Averaged across the rice growing period,elevated CO2 greatly increased TOC and TN contents in the surface water by 7.6% and 11.4%,respectively.(4) The TOC/TN ratio and natural δ15N value in the surface soil showed a decreasing trend under elevated CO2. The above results indicate that elevated CO2 can benefit C and N accumulation in paddy fields. Given the similarity between the paddies and natural wetlands, our results also suggest a great potential for long-term C and N accumulation in natural wetlands under future climate patterns.     

Analysis of the Trend and Seasonal Cycle of Carbon Monoxide Concentrations in an Urban Area (4 pp)

Background, Aim and Scope Air quality is an field of major concern in large cities. This problem has led administrations to introduce plans and regulations to reduce pollutant emissions. The analysis of variations in the concentration of pollutants is useful when evaluating the effectiveness of these plans. However, such an analysis cannot be undertaken using standard statistical techniques, due to the fact that concentrations of atmospheric pollutants often exhibit a lack of normality and are autocorrelated. On the other hand, if long-term trends of any pollutant’s emissions are to be detected, meteorological effects must be removed from the time series analysed, due to their strong masking effects. Materials and Methods The application of statistical methods to analyse temporal variations is illustrated using monthly carbon monoxide (CO) concentrations observed at an urban site. The sampling site is located at a street intersection in central Valencia (Spain) with a high traffic density. Valencia is the third largest city in Spain. It is a typical Mediterranean city in terms of its urban structure and climatology. The sampling site started operation in January 1994 and monitored CO ground level concentrations until February 2002. Its geographic coordinates are W0°22′52″ N39°28′05″ and its altitude is 11 m. Two nonparametric trend tests are applied. One of these is robust against serial correlation with regards to the false rejection rate, when observations have a strong persistence or when the sample size per month is small. A nonparametric analysis of the homogeneity of trends between seasons is also discussed. A multiple linear regression model is used with the transformed data, including the effect of meteorological variables. The method of generalized least squares is applied to estimate the model parameters to take into account the serial dependence of the residuals of this model. This study also assesses temporal changes using the Kolmogorov-Zurbenko (KZ) filter. The KZ filter has been shown to be an effective way to remove the influence of meteorological conditions on O₃ and PM to examine underlying trends. Results The nonparametric tests indicate a decreasing, significant trend in the sampled site. The application of the linear model yields a significant decrease every twelve months of 15.8% for the average monthly CO concentration. The 95% confidence interval for the trend ranges from 13.9% to 17.7%. The seasonal cycle also provides significant results. There are no differences in trends throughout the months. The percentage of CO variance explained by the linear model is 90.3%. The KZ filter separates out long, short-term and seasonal variations in the CO series. The estimated, significant, long-term trend every year results in 10.3% with this method. The 95% confidence interval ranges from 8.8% to 11.9%. This approach explains 89.9% of the CO temporal variations. Discussion The differences between the linear model and KZ filter trend estimations are due to the fact that the KZ filter performs the analysis on the smoothed data rather than the original data. In the KZ filter trend estimation, the effect of meteorological conditions has been removed. The CO short-term componentis attributable to weather and short-term fluctuations in emissions. There is a significant seasonal cycle. This component is a result of changes in the traffic, the yearly meteorological cycle and the interactions between these two factors. There are peaks during the autumn and winter months, which have more traffic density in the sampled site. There is a minimum during the month of August, reflecting the very low level of vehicle emissions which is a direct consequence of the holiday period. Conclusions The significant, decreasing trend implies to a certain extent that the urban environment in the area is improving. This trend results from changes in overall emissions, pollutant transport, climate, policy and economics. It is also due to the effect of introducing reformulated gasoline. The additives enable vehicles to burn fuel with a higher air/fuel ratio, thereby lowering the emission of CO. The KZ filter has been the most effective method to separate the CO series components and to obtain an estimate of the long-term trend due to changes in emissions, removing the effect of meteorological conditions. Recommendations and Perspectives Air quality managers and policy-makers must understand the link between climate and pollutants to select optimal pollutant reduction strategies and avoid exceeding emission directives. This paper analyses eight years of ambient CO data at a site with a high traffic density, and provides results that are useful for decision-making. The assessment of long-term changes in air pollutants to evaluate reduction strategies has to be done while taking into account meteorological variability     

固定CO2氢细菌的筛选及其培养条件优化

从土壤中分离筛选到一株高效固定CO2 的氢氧化细菌—专性化能自养菌BHA 15 ,在最佳培养条件下(培养基 ρ/gL-1:NH4 Cl 4.0 ,Na2 HPO4 ·12H2 O 0 .75 ,KH2 PO4 0 .5 ,MgSO4 ·7H2 O 0 .3;V(H2 )∶V(O2 )∶V(CO2 ) =3 .5∶1∶1;pH =7;最适生长温度θ =30℃ ) ,密闭摇瓶中恒温 (30℃ )培养 40h后 ,菌体浓度 ρ(DW)达 1.6mg/mL ,菌体蛋白含量 71.8% .图 7表 2参 12     

UV-B辐射增强对不同大麦品种生理特性的影响

通过大田试验,研究了UV-B辐射增强对不同生育期3个大麦(Hordeum vulgare)品种光合和蒸腾生理特性的影响。试验设对照(自然光)和辐射增强(辐照强度14.4 kJ.m-2.d-1)2个UV-B辐射水平。结果表明,UV-B辐射增强明显抑制大麦光合作用和蒸腾作用。与对照相比,UV-B辐射增强可降低叶片叶绿素含量、气孔导度、净光合速率和蒸腾速率,但对胞间CO2摩尔分数基本没有影响。不同大麦品种对UV-B辐射增强响应的敏感性存在差异,单2号对UV-B辐射增强较为敏感,而苏啤4号较不敏感。     

基于响应曲面法的臭氧生成敏感性分析

准确判断臭氧(O₃)生成敏感性对O₃污染成因分析和防控对策的制定至关重要.首次利用响应曲面方法设计最优试验方案,基于盒子模式模拟结果,快速量化O₃对其前体物变化的响应.结果表明,CO对O₃有正贡献,NO_x和VOCs与O₃呈现显著非线性关系,当φ(VOCs)与[φ(NO_x)-13.75]比值大于4.17时,为NO_x控制区,小于4.17时,为VOCs控制区;烯烃为影响O₃生成的关键VOCs组分,当φ(烯烃)与[φ(NO_x)-15]比值小于1.10且φ(烯烃)<35×10^-9时,烯烃有利于O₃的生成.响应曲面法在多因素和其交互作用对O₃生成影响的研究中取得了良好效果,为高效判断O₃敏感性提供了新的思路和方法.     

海州露天矿采空区地表CO2通量的试验研究

为探究海州露天矿东邦废弃采空区自然发火状态,基于采空区遗煤自燃特性和气体扩散理论,采用智能土壤气体通量监测系统,以月为单位,对东邦自燃采空区上覆地表CO₂通量开展长周期、多测点连续性监测试验;根据试验区域内地表CO₂通量和土壤温度分布特征,探究地下火区释放CO₂的地表涌出范围和变化情况;同时,着眼于温室气体排放的评估,计算试验区域内的CO₂涌出量,并分析其随时间的变化特征。结果表明:地表CO₂通量与土壤温度有明显正相关性;试验区域地表CO₂高通量区域呈逐月扩大和递增的趋势;CO₂涌出量随月份逐渐递增,试验区域年CO₂涌出量约为3.6×10⁶ m³。     

初始扰动对CO2抑制瓦斯爆炸特性研究*

为了预防实际生产过程中发生的瓦斯爆炸事故,利用20 L球形爆炸装置,通过改变粉尘仓充压压力产生不同的扰动,研究9.5%CH4浓度下不同扰动条件对CO2抑爆特性的影响。通过对所得参数进行分析,得到CO2抑爆特性与初始扰动的关系。研究结果表明:相较于均匀静置状态,初始扰动的存在均能提高CH4的爆炸强度,当引发初始扰动的粉尘仓压力为1.5 MPa时,最大爆炸压力达到0.78 MPa;随CO2浓度增大,爆炸强度整体下降,呈二次下降趋势、最大爆炸压力时间呈上升趋势,且各初始扰动压力间爆炸强度均大于均匀静置状态、最大爆炸压力时间小于均匀静置状态;同时利用CHEMKIN软件得到绝热平衡压力,计算热损失参数发现,同一气体混合比例工况下,初始扰动状态的热损失及热损失分数明显低于均匀静置状态的,且当CO2浓度为15%时,差距最大,不同初始扰动间热损失及热损失分数最小值分别为0.013 19 kJ/m2,17.9%,远小于静置状态下0.036 29 kJ/m2,46.4%,说明初始扰动对于CO2抑爆效果存在削弱作用。