木材干燥导水系数和换水系数的研究

木材(板、方材)的导水系数和换水系数是反映木材干燥或存放过程中水分迁移的重要物性参数。然而,我国对木材导水系数和换水系数的研究和测定工作十分有限。木材干燥有关的理论计算中,常用原苏联的数据。由于这些数据本身可能存在的误差及用于我国树种的可靠程度难以估计,故使理论结果的实际运用受到限制。本文采用等厚试件系数分离法研究和测定了木材干燥过程动态导水系数和换水系数。     

近20年新疆农田生态系统碳足迹时空变化

利用1994—2013年新疆农田生产投入和农作物产量等数据,采用碳排放系数法估算了新疆农田生态系统的碳排放量、碳吸收量及碳足迹的变化动态以及在各县市的空间分布特征。结果表明:新疆农田生态系统的碳排量从1994年的179.46万t增长到2013年的474.15万t;不同年份农业碳排放均主要源于化肥使用量的增加和不科学的灌溉方式,其最大贡献率分别为40.02%和41.56%;农田生态系统的碳吸收量20年间增加了2185.04万t,棉花对新疆农田生态系统的碳吸收量贡献最大,多年平均贡献率达47%;新疆农田生态系统的碳排放量、碳吸收量区域主要集中在南疆的县市并呈现出沿天山对称的趋势;1994—2013年,农田生态系统碳足迹呈现快速增长态势,从1994年的2 732.63×104C·hm-2·a-1增加至2013年的4 474.89×104C·hm-2·a-1,碳足迹增加了283.59×104C·hm-2·a-1,表明新疆农田生态系统存在碳生态盈余的现象,种植结构生态效益指数大于1的年份为11个,种植结构的调整迫在眉睫。     

利用Pt-Rh堇青石整体式催化器控制汽油发动机排气净化的试验

为控制化油器汽油发动机尾气排放,对贵金属Pt-Rh催化器在实际发动机排气条件下进行了研究。用浸渍法制备化油器式汽油发动机的催化器,以适应汽车发动机运行工况多变、空燃比范围宽以及排气HC、CO和NOx体积分数高等实际情况。试验结果表明,应用Pt-Rh堇青石整体式催化器,可以实现在不同的温度、不同的转速、不同的空燃比条件下对发动机尾气HC、CO和NOx同时净化和得到较高的转化效率;在不同的温度范围内,还可以实现HC和CO对NOx的协同还原反应。     

北京和上海终端能源碳排放量影响因素研究

运用IPCC中碳排放量公式,结合能源消费数据,对北京和上海2005～2012年碳排放终端能源总量进行估计;运用LMDI模型定量分析了经济总量、能源结构、产业结构对碳排放的影响.结果表明,2005～ 2012年经济总量上升是推动北京和上海碳排放量增长的主要因素,能源结构调整是降低碳排放量的主要原因,产业结构调整是影响碳排放量原因之一.通过对能源结构和产业结构进一步分析得出北京和上海两市应通过能源结构调整,增加清洁能源消费比率来减少碳排放,上海市应同时发展第三产业促进产业结构调整降低碳排放的结论.     

利用简易工况法对在用汽车排放检测之探讨

在用车尾气排放的治理和监管是中国城市大气环境改善的重点工作之一。利用典型在用车,对国家标准GB18285—2005规定的双怠速法、ASM法、VMAS法和IM195等在用车尾气排放检测方法进行了试验研究,探讨了ASM和VMAS两种检测方法的适用性。     

Meeting the UK's climate change commitments: options for carbon mitigation on agricultural land

Abstract. Under the Kyoto Protocol, the European Union is committed to an 8% reduction in CO₂ emissions, compared to baseline (1990) levels, during the first commitment period (2008–2012). However, within the overall EU agreement, the UK is committed to a 12.5% reduction. In this paper, we estimate the carbon mitigation potential of various agricultural land-management strategies (Kyoto Article 3.4) and examine the consequences of UK and European policy options on the potential for carbon mitigation.
We show that integrated agricultural land management strategies have considerable potential for carbon mitigation. Our figures suggest the following potentials (Tg yr⁻¹) for each scenario: animal manure, 3.7; sewage sludge, 0.3; cereal straw incorporation, 1.9; no-till farming, 3.5; agricultural extensification, 3.3; natural woodland regeneration, 3.2 and bioenergy crop production, 4.1. A realistic land-use scenario combining a number of these individual management options has a mitigation potential of 10.4 Tg C yr⁻¹ (equivalent to about 6.6% of 1990 UK CO₂-carbon emissions). An important resource for carbon mitigation in agriculture is the surplus arable land, but in order to fully exploit it, policies governing the use of surplus arable land would need to be changed. Of all options examined, bioenergy crops show the greatest potential. Bioenergy crop production also shows an indefinite mitigation potential compared to other options where the potential is infinite.
The UK will not attempt to meet its climate change commitments solely through changes in agricultural land-use, but since all sources of carbon mitigation will be important in meeting these commitments, agricultural options should be taken very seriously.     

适宜节水灌溉模式抑制寒地稻田N_2O排放增加水稻产量

2014年在大田试验条件下,设置控制灌溉、间歇灌溉、浅湿灌溉及淹灌4种水分管理模式,采用静态暗箱-气相色谱法田间观测寒地水稻生长季N2O排放特征,研究不同灌溉模式对寒地稻田N2O排放的影响及N2O排放对土壤环境要素的响应,同时测定水稻产量,以期为寒地稻田N2O排放特征研究提供对策。结果表明:不同灌溉模式下N2O排放的高峰均出现在水分交替频繁阶段,水稻生育阶段前期,各处理N2O排放都处于较低水平,泡田期几乎无N2O排放。与淹灌相比,间歇灌溉使N2O排放总量增加47.3%,控制灌溉和浅湿灌溉使N2O排放总量减少40.7%和39.6%。寒地稻田N2O排放通量与土壤硝态氮含量关系密切,与土壤10 cm温度显著相关(P0.05)。水稻生长期间各处理N2O排放顺序间歇灌溉淹灌,二者均显著高于浅湿灌溉和控制灌溉(P0.05)。各处理水稻产量以浅湿灌溉最低、其他方式差异不显著。可见,间歇灌溉有助于提高水稻产量,但会促进稻田N2O的排放。在综合考虑水稻产量及稻田温室效应的需求下,控制灌溉为最佳灌溉方式,应予以高度重视。该研究可为黑龙江寒地稻作区选择节水减排模式提供科学支撑。     

污泥及其混合堆肥对番茄土壤性质和N_2O排放的影响

目前关于污泥及其生物质堆肥的土地利用过程中土壤性质变化和温室气体排放数据十分缺乏,难以满足农田土壤氮素保存和温室气体减排的需求。该研究通过在番茄种植过程中添加800 kg/hm2新鲜污泥(S-H)、400 kg/hm2新鲜污泥(S-L)、800 kg/hm2秸秆堆肥(VM-S)和800 kg/hm2猪粪堆肥(VM-M),开展土壤性质、无机氮形态、作物生长以及N2O排放特征的研究。结果表明:堆肥处理显著增加了土壤电导率(electric conductivity,EC)(P0.05),其中猪粪堆肥时土壤EC值最大。添加污泥和堆肥都使土壤p H值显著上升(P0.05),最终趋于中性,且VM-M对土壤酸化的抑制效果略优于VM-S。污泥和堆肥处理时土壤NO3--N浓度显著高于对照,且各处理组NO3--N浓度均随时间逐渐下降,NO3--N主要被番茄吸收,部分NO3--N从土壤上层淋溶至下层;NH4+大多数被氧化为NO3-,部分NH4+被植物吸收。在施入的无机氮量相等情况下,VM-M、VM-S、S-H处理组中番茄地上部分生物量分别为1 515、1 383、1 103 g/株,株高分别为56.8、54.5、51.3 cm,对番茄生长的促进效果为VM-MVM-SS-H,而S-H比S-L多施入的氮肥对番茄生长并未起到明显促进作用(P0.05)。与对照相比,污泥或生物质堆肥都显著提高了土壤N2O的排放(P0.05),各处理组N2O的排放均集中于施肥后的前20天,且土壤N2O的排放通量大小顺序为S-L(0.76 kg/(hm2·a))VM-M(0.95 kg/(hm2·a))VM-S(1.19 kg/(hm2·a))S-H(1.71 kg/(hm2·a))。因此,在进行污泥及其生物质堆肥的土地利用时,应考虑有机肥的种类及其施用量,以在提高作物产量的同时改善土壤并减少温室气体排放,在进行污泥的农田利用时可先将污泥与畜禽粪堆肥。     

不同土地利用方式下土壤温度与土壤水分对黑土N2O排放的影响

采用静态箱一气象色谱法,对黑土区3种不同土地利用方式（草地、裸地和农田）下土壤氧化亚氮（N：O）的排放特征及其与土壤温度和土壤水分的关系进行研究。结果显示：试验监测期间（2011年5月27日-9月30日）,不同土地利用方式下,土壤N：0累积排放量分别为草地52．08mgN·m^-2裸地64．43mgN·m^-2农田70．16mgN·m^-2,农田土壤N：O累积排放量比草地和裸地分别高出35％和9％,草地、裸地和农田的N2O平均排放通量分别为16．56、20．36、21．44μgN·m^-2·h^-1。草地和裸地中,土壤N2O排放通量与土壤温度和土壤水分（充水孔隙度,WFPS）相关性均不显著,但在农田中,土壤N20排放通量与土壤温度（5cm和10cm）和土壤水分（5cm）均呈显著正相关（P〈0．05）。另外,土壤N2O累积排放量与土壤硝态氮和矿质氮含量均呈正相关关系。研究表明,黑土草地开垦可促进土壤N2O的排放,且不同土地利用方式下土壤N2O排放的主要影响因子不同。     

Changes in chemical and biological properties of a sodic clay subsoil with addition of organic amendments

An experiment was performed to examine the chemical and biological effects on high clay sodic subsoil following the incorporation and incubation with organic amendments. The main treatments consisted of amendments with wheat shoots, lucerne pellets and peat, and these were compared to gypsum addition. Additional treatments were residues of chickpea and canola, chicken manure and sawdust. All materials were finely ground and added to crushed and sieved soil at the rate of 1% by weight. Wheat, canola and chickpea residues and chicken manure resulted in modest reductions in soil sodicity. Carbon and N mineralization were related to the soluble C/total N ratio in the amendment. The initial mineralization of wheat amendment was rapid due to its soluble C content, but then slowed to have the lowest loss, of around one third of added C, of all the plant residues after 174 days. In comparison, lucerne-amended soil increased total N and lost almost half of its C after the 174-day incubation. The canola stubble amendment showed the highest carbon loss, losing 64% of its added C. The addition of gypsum resulted in high soil electrical conductivity which suppressed respiration, compared to the control soil, indicating a detrimental effect on microbial activity due to the high electrolyte concentration in the soil. The peat amendment, with a low-soluble C content, showed a similar respiration rate to the control soil, confirming that a source of soluble C is important for the initiation of rapid biological activity. Soil pH was significantly increased (by 0.6 of a pH unit) with addition of chicken manure, and still remained higher than control soil after 174 days of incubation. Lucerne was the only plant residue to increase soil pH, with the effect being sustained for 56 days. The study demonstrated how some organic amendments can improve chemical fertility and biological activity in high clay sodic subsoil, and at the same time contribute, after 25 weeks incubation, to an increase in carbon content.