西安东南部7月份土壤CO2释放量和释放规律研究

根据碱溶液吸收法,对西安东南部地区7月份不同植被条件下土壤CO2释放量进行了昼夜观测,观测资料显示,西安东南部地区7月份土壤CO2释放量一昼夜内具有明显变化,从当日9时到次日9时,CO2释放量表现出由低变高再变低的规律,土壤CO2释放量变化与温度变化具有相同的特征,但释放量的变化具有滞后性,相对于温度的变化滞后4－6h,温度是决定土壤CO2释放量昼夜变化规律的主要因素,它的升高和降低分别造成了土壤CO2释放量的增加和减少,不同植被条件下,土壤CO2释放量不同,林地释放量大于草地,草地释放量大于裸地,夜间12h释放量大于白天12h释放量。     

西安东南部7月份土壤CO_2释放量和释放规律研究

根据碱溶液吸收法 ,对西安东南部地区 7月份不同植被条件下土壤CO2 释放量进行了昼夜观测 .观测资料显示 ,西安东南部地区 7月份土壤CO2 释放量在一昼夜内具有明显变化 ,从当日 9时到次日 9时 ,CO2 释放量表现出由低变高再变低的规律 .土壤CO2 释放量变化与温度变化具有相同的特征 ,但释放量的变化具有滞后性 ,相对于温度的变化滞后 4～ 6h .温度是决定土壤CO2 释放量昼夜变化规律的主要因素 ,它的升高和降低分别造成了土壤CO2 释放量的增加和减少 .不同植被条件下 ,土壤CO2 释放量不同 ,林地释放量大于草地 ,草地释放量大于裸地 ,夜间 1 2h释放量大于白天 1 2h释放量 .     

西安南郊和蓝田夏季土壤CO2排放量的变化研究

根据NaOH溶液吸收CO2原理，对西安南郊和蓝田不同成因土层CO2释放量进行了观测，探讨了土壤CO2释放量的变化规律及其影响因素。资料表明，关中地区夏季土壤(厚土层)CO2释放量变化规律与气温变化规律负相关，CO2释放量存在一定的“滞后性”，一般滞后4～6h；而薄土层土壤CO2释放量变化规律与气温变化规律正相关，CO2释放量不存在“滞后性”，且释放量明显小于厚土层；土壤CO2释放量的变化与温度和天气密切相关，温度高、天气晴朗时释放量大，反之则小；厚土层CO2释放量白天小于夜间，白天约占1／3，夜间约占2／3；薄土层CO2释放量白天大于夜间，白天约占2／3，夜间约占1／3，薄层土CO2观测揭示了CO2释放量和变化规律都与土层厚度有关。     

西安南郊和蓝田夏季土壤CO_2排放量的变化研究

根据NaOH溶液吸收CO2原理,对西安南郊和蓝田不同成因土层CO2释放量进行了观测,探讨了土壤CO2释放量的变化规律及其影响因素.资料表明,关中地区夏季土壤(厚土层)CO2释放量变化规律与气温变化规律负相关,CO2释放量存在一定的"滞后性",一般滞后4～6h;而薄土层土壤CO2释放量变化规律与气温变化规律正相关,CO2释放量不存在"滞后性",且释放量明显小于厚土层;土壤CO2释放量的变化与温度和天气密切相关,温度高、天气晴朗时释放量大,反之则小;厚土层CO2释放量白天小于夜间,白天约占1/3,夜间约占2/3;薄土层CO2释放量白天大于夜间,白天约占2/3,夜间约占1/3.薄层土CO2观测揭示了CO2释放量和变化规律都与土层厚度有关.     

西安吴家坟秋季土壤的碳释放规律研究

通过对西安呈家坟秋季土壤CO2释放量的监测，研究了影响土壤CO2释放量变化的主要因素及在不同温度、湿度条件作用下，土壤CO2释放量变化的特点，总结出西安南郊地区秋季土壤CO2释放量的变化主要随着温度而变化，即气温降低，土壤CO2释放量逐渐减少，在昼夜时段中，土壤CO2释放量也随温度变化，但相比温度变化有明显的滞后，大约滞后6h，且夜间释放量明显高于白天。     

农田土壤生态系统冬小麦夏玉米轮作CO2排放特征研究

采用静态箱法对旱地农田冬小麦-夏玉米轮作生态系统CO2排放进行了定位观测,并利用气象色谱进行分析而研究了北方地区典型旱地农田土壤CO2排放特征.结果表明,旱地农田土壤冬小麦-夏玉米轮作期间CO2的平均排放通量由大到小依次排列为:无机-有机肥配合施用的处理110.78 mg·m-2·h-1,单施无机肥处理79.58 mg·m-2·h-1,无追肥处理74.20 mg·m-2·h-1,休闲地54.91 mg·m-2·h-1.作物生长状况与土壤温度是影响土壤呼吸强度的主要因素,而试验数据分析结果表明土壤可溶性有机碳(DOC)与CO2排放通量无直接关系.其中,小麦拔节期、玉米的拔节期到喇叭口期的土壤CO2排放通量均较高.     

杨-桤混交林及其凋落物对土壤氮矿化的影响

【目的】研究含氮量中等的立地条件下杨-桤混交林相比于杨树纯林能否增加土壤养分,分析桤木是否为合适的固氮树种,探讨桤木与杨树营造混交林以缓解人工林连栽带来的土地肥力衰退问题。【方法】以苏北地区杨树人工纯林以及杨-桤(1∶1)混交林为研究对象,采用尼龙网袋法观察两种林分下凋落叶质量分解以及养分释放的过程,比较两种凋落物处理(去除凋落物与保留凋落物)对土壤全氮以及碱解氮含量的影响。采用树脂芯田间原位培养法,研究杨-桤混交林与杨树纯林两种林分在两种凋落物处理下,林地土壤氮年净矿化量的变化。【结果】营造杨-桤混交林显著提高了林地土壤全氮和碱解氮含量。杨树纯林凋落物分解时需从周围土壤中吸收更多氮素,且分解速率较慢。杨-桤混交林凋落物分解更快进入氮释放状态,因此去除凋落物后混交林土壤碱解氮显著减少。保留凋落物处理下,杨-桤混交林中每公顷土壤氮年净氨化量显著高于杨树纯林中的,去除凋落物后两者差异不显著。【结论】研究发现,桤木是杨树较合适的伴生树种,营造杨-桤混交林可以起到增加土壤全氮和碱解氮含量的作用,有助于缓解杨树纯林连栽带来的地力下降问题。混交林凋落物分解速率与氮素释放速率更快,有利于人工林生态系统氮循环。保留凋落物处理下,混交林中每公顷土壤氮年净氨化量显著高于杨树纯林的,而每公顷土壤氮年净硝化量没有显著差异,表明混交林凋落物分解释放的氮素主要促进土壤氨化过程,对土壤硝化过程影响较弱。     

北方农牧交错带不同土地利用方式土壤呼吸速率探究

农牧交错带地区土地利用方式多变,人为的改变土地利用方式会影响土壤释放CO2的速率.分别对新开垦农田、多年耕种农田、退耕还草草地、多年生草地4种利用类型的土壤温度、土壤有机碳含量、土壤呼吸速率进行监测和研究,结果表明：4种土地利用类型土壤呼吸速率的日变化图像呈单峰性曲线,其中草地平均呼吸速率最大,为0.85g·m-2·d-1.4种土地利用类型土壤温度与土壤呼吸速率呈正相关关系,其中新开垦农田变化明显,K值最高,达到0.045.从整个生长季来看,4种土地利用类型平均呼吸速率表现为新开农田＞草地＞还草草地＞农田,分别为0.97g·m-2·d-1、0.85g·m-2·d-1、0.77g·m-2·d-1和0.56g·m-2·d-1.0-10cm和10-20cm土层土壤有机碳含量大小关系与土壤呼吸速率基本吻合.试验表明不论对草地进行开垦还是对农田进行退耕还草都会增加土壤CO2的释放.     

不同土地利用方式下温度对土壤CO_2排放的影响

选取河南省周口市麦玉轮作农田、草地和林地等3种不同利用方式土地作为研究对象,采用静态碱液吸收法测定0-20 cm土层土壤在15℃、25℃和35℃条件下CO_2排放动态.结果表明:不同土地利用方式土壤在不同的温度下,土壤CO_2累积释放量呈现出35℃25℃15℃的趋势. 3种土壤CO_2释放速率呈逐渐减缓的趋势.在相同的温度条件下,不同土地利用方式土壤CO_2释放量有明显差异,土壤CO_2累积释放量表现为草地传统耕地林地.     

温室二氧化碳浓度测控系统

为解决设施园艺中二氧化碳( CO2) 浓度的检测与控制问题,研制了一种基于钠超离子导体( NASICON) 固体电解质传感器的温室CO2测控系统,该系统包括CO2测量节点、无线通信网络和控制终端。采用STM32 微处理器处理采集到的CO2 浓度信息,使用模糊比例-积分-微分( PID: Proportional Integration Differential) 算法控制CO2气体的释放,从而智能调节温室内CO2气体的浓度,使其达到作物所需数值。在实验室条件下,对设计的CO2传感器节点进行了标定和稳定性测试。对体积分数为400 × 10 － 6 和1 000 × 10 － 6 的CO2气体样品分别进行了＞ 8 h 的长时间浓度测量,其相对波动小于2． 5%。在国信集团现代农业基地温室对所研制的CO2浓度测控系统进行实地测试的结果显示,当设定的CO2浓度的期望值为800 × 10 － 6 时,调控后CO2体积分数的波动范围约为± 40 × 10 － 6。现场应用试验表明,该系统具有较好的实用性,且成本低廉、集成度高,具有一定的推广价值。     

Energy requirement for symbiotic nitrogen fixation

Comparing the energy required by legumes for symbiotic nitrogen fixation with that of assimilation of nitrate, Gibson concluded the costs to be about the same. About 15% of net photosynthetic production by the plant may be used in meeting its nitrogen requirements. If energy for the fixation of nitrogen symbiotically and that for the assimilation of NH4+ or NO3- from the soil solution are both provided by the chemical products of photosynthesis, then the CO2 respired in supplying that energy must contribute to the total efflux of CO2 from the plant in the dark. McCree and Thornley have discussed methods of partitioning the dark CO2 efflux into a growth (synthesis) and a maintenance component. Both nitrogen fixation and nitrogen assimilation can be expected to contribute to the CO2 flux associated with synthesis. If Gibson is correct, nodulated plants using only symbiotically fixed nitrogen should have the same growth coefficient as non-nodulated plants supplied with exogenous mineral nitrogen when grown in the same conditions. I have examined this hypothesis using a modification of the method used by McCree with Trifolium subterraneum L. cultivar Woogenellup as test material.     

不同浓度CO2对马尾松幼苗光合特性及单萜烯释放的影响

【目的】研究CO₂浓度升高对马尾松(Pinus massoniana)幼苗光合特性和单萜烯释放的影响,以了解马尾松挥发性有机物(BVOCs)排放对气候变化的响应机制。【方法】利用开顶式气室(OTC),依据政府间气候变化专门委员会(IPCC)第5次评估报告,设置1 000、750、550 μmol/mol 3个CO₂熏气浓度梯度,并与未经CO₂熏气处理的OTCs中CO₂平均浓度(437 μmol/mol,CK)进行对比,研究了中国南方主要造林树种马尾松幼苗净光合速率、叶绿素含量、气孔导度及单萜烯释放的变化规律。【结果】经过60 d的浓度为750及1 000 μmol/mol CO₂熏气处理,马尾松幼苗的叶绿素总含量下降约 17.54%和29.82%;60 d高浓度CO₂处理的马尾松幼苗在环境大气中净光合速率及气孔导度显著低于对照组,且浓度为1 000 μmol/mol CO₂处理组最低;相较于对照组,CO₂浓度升高使马尾松幼苗的单萜烯释放速率下降,在60 d时达到显著水平。马尾松幼苗的单萜烯释放速率与叶片净光合速率及气孔导度呈显著正相关。【结论】高CO₂浓度条件下,马尾松幼苗叶片光合速率和气孔导度的下降可能是单萜烯释放速率降低的原因。     

腾格里沙漠南缘2种沙地灌木植物的光合特征

 对沙坡头地区人工自然植被中的主要植物种油蒿(Artemisia ordosica)和柠条(Caragana korshinskii)光合特征进行了研究,分析了2种沙地灌木植物光合速率(Pn)、微环境因子(光合有效辐射PAR、气温t、相对湿度RH)以及植物叶片气孔导度(Gs)、胞间CO₂浓度比(Ci)、气孔限制值(Ls)、蒸腾速率(E)及水分利用效率(WUE)等的变化特点.结果表明,2种沙地灌木植物的净光合速率日变化曲线呈双峰型.其中光合速率最大值出现在9:00左右,17:00左右出现第2峰值,这是沙地植物对强光照、高气温、低湿度的干旱自然环境条件的一种响应.2种沙地灌木植物光合作用的变化既受气孔因素的影响,也受非气孔因素的影响.其中在7:00~9:00与17:00~19:00时,两者光合速率的增加不仅仅是由于气孔导度的增加造成的,而9:00~15:00期间,植物光合速率下降的主要原因是气孔限制.以上各项光合特征指标的综合分析表明:在研究区自然环境条件下,油蒿比柠条具有更好的光合适应特性.     

A possible important CO2 sink by the global water cycle

The locations, magnitudes, variations and mechanisms responsible for the global CO2 sink are uncertain and under debate. Here, we show, based on theoretical calculations and evidences from field monitoring results, that there is a possible important CO2 sink （as DIC-dissolved inorganic carbon） by the global water cycle. The sink constitutes up to 0.8013 Pg C/a （or 10.1% of the total anthropogenic CO2 emission, or 28.6% of the missing CO2 sink）, and is formed by the CO2 absorption of water and subsequent enhanced consumption by carbonate dissolution and aquatic plant photosynthesis. Of the sink, 0.5188 Pg C/a goes to sea via precipitation over sea （0.2748 Pg C/a） and continental rivers （0.244 Pg C/a）, 0.158 Pg C/a is released to the atmosphere again, and 0.1245 Pg C/a is stored in the continental aquatic ecosystem. Therefore, the net sink could be 0.6433 Pg C/a. This sink may increase with the global-warming-intensified global water cycle, the increase in CO2 and carbonate dust in atmosphere, and reforestation/afforestation, the latter increasing soil CO2, and thus the concentration of the DIC in water.     

撞击流吸收器吸收性能实验研究

：利用清水吸收空气中的ＣＯ２,在实验室内考察了撞击流吸收器的吸收性能,并与具有内循环的喷射式吸收器、鼓泡式吸收器进行了对比。实验结果表明,撞击流吸收器的吸收率和体积传质系数明显高于具有内循环的喷射式吸收器和鼓泡式吸收器。对吸收器用于有固体产物生成的吸收过程进行的初步实验表明,撞击流吸收器对Ｈ２Ｓ的吸收率比具有内循环的喷射式吸收器高,且在吸收过程中,无固体产物堵塞喷嘴现象出现。这一结果对进一步将撞击流吸收器用于有固体产物生成的化学吸收过程的研究具有指导意义     

Variation of δ13C in karst soil in Yaji Karst Experiment Site,Guilin

This study deals with δ13C variation in karst soil system of Yaji Karst Experiment Site, Guilin, a typical region of humid subtropical karst formations. Samples of near ground air, plant tissue, soil and water (soil solution and karst spring) were respectively collected on site in different seasons during 1996-1999. Considerable variation of δ13C values are not only found with different carbon pools of soil organic carbon, soil air CO2 and soil water HCO-3, but also with the soil depths and with different seasons during a year.The δ13C values of CO2 both of near ground air and soil air are lower in July than those in April by 1%-4‰ PDB. Our results indicate that the δ13C values of carbon in the water and air are essentially dependent on interface carbon interaction of air-plant--soil-rock--water governed by soil organic carbon and soil CO2 in the system.     

Effects of elevated CO2 on growth and carbon partitioning in rice

Rice (\%Oryza sativa\% cv. Jindao 1187) was grown in open_top chambers which contained ambient and enriched CO\-2. CO\-2 elevation stimulated rice tillering during early vegetative stage. However, panicle dry weight per plant did not change at maturity stage. Root biomass was enhanced by high CO\-2. Root / shoot ratio was increased under high CO\-2 at maturity, indicating more carbon allocation to the below_bround part in rice under high CO\-2.     

Potential fly-ash utilization in agriculture: A global review

Though in last four decades various alternate energy sources have come into the limelight, the hyperbolic use of coal as a prime energy source cannot be counterbalanced. Disposal of high amount of fly-ash from thermal power plants absorbs huge amount of water, energy and land area by ash ponds. In order to meet the growing energy demand, various environmental, economic and social problems associated with the disposal of fly-ash would continue to increase. Therefore, fly-ash management would remain a great concern of the century. Fly-ash has great potentiality in agriculture due to its efficacy in modification of soil health and crop performance. The high concentration of elements (K, Na, Zn, Ca, Mg and Fe) in fly-ash increases the yield of many agricultural crops. But compared to other sectors, the use of fly-ash in agriculture is limited. An exhaustive review of numerous studies of last four decades took place in this paper, which systematically covers the importance, scope and apprehension regarding utilization of fly-ash in agriculture. The authors concluded that though studies have established some solutions to handle the problems of radioactivity and heavy metal content in flyash, long-term confirmatory research and demonstration are necessary. This paper also identified some areas, like proper handling of dry ash in plants as well as in fields, ash pond management (i.e., faster decantation, recycling of water, vertical expansion rather than horizontal), monitoring of soil health, crop quality, and fate of fly-ash in time domain, where research thrust is required. Agricultural lime application contributes to global warming as Intergovernmental Panel on Climate Change (IPCC) assumes that all the carbon in agricultural lime is finally released as CO2to the atmosphere. It is expected that use of fly-ash instead of lime in agriculture can reduce net CO2emission, thus reduce global warming also.     

燃煤在O_2/CO_2方式下SO_2生成特性的研究

研究了合山煤在O2 /CO2 方式下SO2 的生成特性 .结果表明在O2 /CO2 方式下 ,由于燃煤的燃烧特性和钙基吸收剂的煅烧分解特性不同于传统燃烧方式 ,SO2 的生成速度加快 ,生成量较空气气氛下大为减少 ,钙基吸收剂的脱硫率随温度升高而增加 ,表明O2 /CO2 方式有利于钙基吸收剂高温脱硫     

The v-v energy transfer of highly vibrationally excited states (I)──Vibrational quenching of CO(v) by CO_2

The relaxation of the highly vibrationally excited CO (v=1-8) by CO\-2 is studied by time_resolved Fourier transform infrared emission spectroscopy (TR FTIR). 193 nm laser photolysis of the mixture of CHBr\-3 with O\-2 generates the highly vibrationally excited CO(v) molecules. TR FTIR records the intense infrared emission of CO(v→v-1). The vibrational populations of each level of CO(v) have been determined by the method of spectral simulation. Based on the evolution of the time resolved populations and the differential method, 8 energy transfer rate constants of CO(v=1-8) to CO 2 molecules are obtained: (5.7±0.1), (5.9±0.1), (5.2±0.2), (3.4±0.2), (2.4±0.3), (2.2±0.4), (2.0±0.4) and (1.8±0.6) (10 -14 cm 3·molecule -1·s -1), respectively. A two_channel energy transfer model can explain the feature of the quenching of CO(v) by CO 2. For the lower vibrational states of CO, the vibrational energy transfers preferentially to the υ\-3 mode of CO 2. For the higher levels, the major quenching channel changes to the vibrational energy exchange between CO(v→v-1) and the υ\-1 mode of CO 2.