淹水条件下FACE处理的水稻以及小麦秸秆的分解及产物

Winter wheat and rice straw produced under ambient and elevated CO2 in a China rice-wheat rotation free-air CO2 enrichment (FACE) experiment was mixed with a paddy soil at a rate of 10 g kg-1 (air-dried), and the mixture was incubated under flooded conditions at 25 ℃ to examine the differences in decomposition as well as the products of crop residues produced under elevated CO2. Results showed that the C/N ratio and the amount of soluble fraction in the amended rice straw grown under elevated CO2 (FR) were 9.8% and 73.1% greater, and the cellulose and lignin were 16.0% and 9.9% lesser than those of the amended rice straw grown under ambient CO2 (AR), respectively. Compared with those of the AR treatment, the CO2-C and CH4-C emissions in the FR treatment for 25 d were increased by 7.9% and 25.0%, respectively; a higher ratio of CH4 to CO2 emissions induced by straw in the FR treatment was also observed. In contrast, in the treatments with winter wheat straw, the CO2-C and CH4-C productions, the ratio of straw-induced CH4 to CO2 emissions, and the straw composition were not significantly affected by elevated CO2, except for an 8.0% decrease in total N and a 9.7% increase in C/N ratio in the wheat straw grown under elevated CO2. Correlation analysis showed that the net CO2-C and CH4-C emissions from straw and the ratio of straw-induced CH4 to CO2 emissions were all exponentially related to the amount of soluble fraction in the amended straw (P < 0.05). These indicated that under flooded conditions, the turnover and CH4 emission from crop straw incorporated into soil were dependent on the effect of elevated CO2 on straw composition, and varied with crop species. Incorporation of rice straw grown under elevated CO2 would stimulate CH4 emission from flooded rice fields, whereas winter wheat straw grown under elevated CO2 had no effect on CH4 emission.     

Biomass burning in Brazil's Amazonian “arc of deforestation”: Burning efficiency and charcoal formation in a fire after mechanized clearing at Feliz Natal, Mato Grosso

Estimates of greenhouse-gas emissions from deforestation are highly uncertain because of high variability in key parameters and because of the limited number of studies providing field measurements of these parameters. One such parameter is burning efficiency, which determines how much of the original forest's aboveground carbon stock will be released in the burn, as well as how much will later be released by decay and how much will remain as charcoal. In this paper we examined the fate of biomass from a semideciduous tropical forest in the “arc of deforestation,” where clearing activity is concentrated along the southern edge of the Amazon forest. We estimated carbon content, charcoal formation and burning efficiency by direct measurements (cutting and weighing) and by line-intersect sampling (LIS) done along the axis of each plot before and after burning of felled vegetation. The total aboveground dry biomass found here (219.3 Mg ha⁻¹) is lower than the values found in studies that have been done in other parts of the Amazon region. Values for burning efficiency (65%) and charcoal formation (6.0%, or 5.98 Mg C ha⁻¹) were much higher than those found in past studies in tropical areas. The percentage of trunk biomass lost in burning (49%) was substantially higher than has been found in previous studies. This difference may be explained by the concentration of more stems in the smaller diameter classes and the low humidity of the fuel (the dry season was unusually long in 2007, the year of the burn). This study provides the first measurements of forest burning parameters for a group of forest types that is now undergoing rapid deforestation. The burning parameters estimated here indicate substantially higher burning efficiency than has been found in other Amazonian forest types. Quantification of burning efficiency is critical to estimates of trace-gas emissions from deforestation.     

林火碳排放研究进展

火是森林生态系统主要的干扰因子, 森林火灾的频繁发生不仅使森林生态系统遭到破坏, 同时也造成了含碳温室气体的大量释放。综述了火烧面积、森林可燃物以及燃烧效率等主要因子对森林火灾排放碳量估计的影响, 分析了这一领域未来研究发展趋势。大量研究表明:1)卫星遥感是估测大尺度上森林过火面积的主要手段, 随着高分辨率卫星的应用, 森林火灾面积的估计精度不断得到提高。目前的研究主要集中于大尺度上林火面积的估计和估算方法的改进。2)遥感数据是目前估计大尺度可燃物燃烧量的有效手段, 利用遥感数据的同时结合有效可燃物计算模型, 运用多元线性与非线性分析结合等方法提高对可燃物燃烧量的估计。3)燃烧效率是决定可燃物消耗量的主要因子, 也是估计森林火灾释放含碳气体量的关键。未来的研究是利用高分辨率的遥感数据, 结合复杂的可燃物计算模型, 更精确地估计林火碳排放。     

康平县农业机械能耗现状与节能减排措施

近年来康平县农业装备水平快速提高,农业机械节能减排问题越来越突出。介绍康平县农业机械能耗现状,分析农机能耗过大的主要原因,有针对性地提出农业机械节能减排技术措施,以推进康平县农业农村节能减排工作进程。     

黑龙江省工业SO_2排放与经济发展关系演变及成因分析

经济与环境协调发展是建设资源节约型和环境友好型社会的核心内容。通过对1981-2006年黑龙江省工业SO2排放与经济发展之间动态关系的分析,结果表明:1981年以来黑龙江省工业SO2排放量经历了先减后升的过程,排放强度显著下降,主要来源于能源生产、造纸及纸制品、非金属矿物制品等制造业部门,资源型城市的排放量占全省工业SO2排放量的50%以上,而综合性工业城市则占到1/3左右。EKC模型对工业SO2排放与人均GDP之间关系的模拟结果表明,二者之间呈现较为典型的U型关系。分解分析结果显示,规模效应、清洁技术效应是影响工业SO2排放的重要因素,其中清洁技术效应对工业SO2减排目标的实现具有决定性控制作用。     

青岛市种植业主要投入要素碳排放及其强度分析

种植业碳排放是总碳足迹的重要组成部分,其来源及碳排放强度已成为减少温室气体排放的急需探讨的科学问题。本研究通过追溯种植业碳排放的来源,选定主要投入要素的碳排放系数,核算青岛市1995年至2012年种植业碳排放及其碳排放强度。结果表明：（1）1995-2012年种植业碳排放总体上是逐年减少的,整个研究阶段可分为两个时期,即1995-2007年碳排放保持稳定时期,与2008-2012年碳排放逐渐减少时期;（2）种植业主要投入要素碳排放所占比例显示,氮肥贡献率最大,达43.31%,而各投入要素碳排放的增长率显示,农膜变化率最大,达到85.51%;（3）碳排放强度表明产值和产量的提高,可以通过农田投入要素的有效组合和高效利用得到,并不会引起碳排放的增加。     

生物炭施用对农业生产与环境效应影响研究进展分析

生物炭(Biochar)因其特殊性质而被广泛应用在土壤改良和固碳减排等方面,因潜力很大,备受国内外学者的关注。然而,生物炭性质不仅因生物质制备材料来源不同而有所差异,还受到热解温度和工艺的影响。同时,生物炭性质和土壤条件差异也在较大程度上影响其改良土壤效果和固碳减排成效。综述近年来国内外有关生物炭在农田水土环境及固碳减排影响的研究进展,总结了生物炭在农业领域、固碳减排及盐碱地改良等方面的研究成果,分析了现存问题,并对生物炭在农业相关领域的研究应用进行了探讨,旨在为广泛应用生物炭技术提供借鉴和参考。     

山东省农地集约利用的碳排放效率分析与低碳优化

建立农地集约利用投入产出指标体系,对山东省17个地级市的农地集约利用过程中的碳排放效率进行分析,研究农地集约利用程度与碳排放效率的关系。结果表明,农地集约利用度的高低与碳排放效率高低并不具有普遍的一致性,山东省农地集约利用度较高的地区主要分布在传统农业区和部分发达城市;济南、青岛、烟台3个经济较发达的地级市农地集约利用碳排放效率普遍偏低;农地技术(如育种、灌溉和机械)投入不足,化肥、农药、电力投入过多是农地集约利用的碳排放效率低的普遍原因。针对各地级市的特点,提出了如何在以碳排放为成本的前提下实现农地集约利用的最优,探索低碳优化措施。     

Acoustic emission behavior of shale under four point bending test

PXWAE Acoustic Emission System is useol to investigate the acoustic emission behavior of shale under four point bending test. In these tests, the maximum bending stress, bending strain, acoustic emission hits, acoustic emission energy and etc., are recorded. The results show that when vertical loads impose on the shale sample which has horizontal stratification planes, Kaiser effect does exist under four point bending tests. Kaiser point can be recognized directly from the stress vs. cumulative AE hits curve. But by the impact of shale’s stratifications and local failure during the tests, strain relaxation occur which makes it difficult to determine the Kaiser point only by the strain vs. acoustic emission curve. An accurate conclusion can be achieved by a comprehensive judgment combing with all test data, as well as the failure mode of rock sample. The research on acoustic emission behavior of rock in the stress state during bending tests to some extend can provide guidance to engineering practice for stability monitoring of mine roof or separation layer with acoustic emission monitoring technology.     

Uniaxial Experimental Analysis on Creep Properties of Deep Limestone

The uniaxial creep tests were carried out for deep limestone from Chongqing adoptal by the MTS815 servo controlled rock mechanical test system. Meanwhile, the DISP 2 based AE system was used to test acoustic emission (AE) signal. It is found that AE can better reflect rock microstructure such as diffusion of lattice defects, opening and close of the pore and fracture, compatible deformation among particles, the generation and connection of micro ruptures. Through different creep model parameter inversion, 〖JP2〗it is concluded that either the logarithmic function creep model or the exponential function can better reflect deep rock creep deformation behavior and the logarithmic function creep model is much better. 〖JP〗