雪里蕻腌菜卤汁中有机酸成分气相色谱分析

应用气相色谱法，以十二烷为内标，雪里蕻腌菜卤汁中挥发及不挥发性有机酸醋酸、丙酸、丁酸、乳酸及琥珀酸和苹果酸经处理丁酯化后在HP-1毛细管柱上得到了完全分离定量。对各有机酸组分的含量与比峰面积或比峰高进行了回归分析，相关系数在0．9904-0．9968之间。醋酸、乳酸和琥珀酸以及苹果酸在样品中的回收率分别为91．2％、86．2％、96．5％和88．5％。且可简化样品中有机酸组分的分离提取操作，简化后的检测定量结果仍很理想。     

无公害苹果生产基地环境质量评价方法

论述了无公害苹果生产基地大气、土壤、灌溉水环境质量评价的原理和方法。阐明了无公害苹果生产基地大气、土壤、灌溉水样品采集原则、样品处理和分析方法,根据分析结果由单项污染指数法和综合污染指数法评价无公害苹果生产基地的环境质量,并提出了单项污染指数和综合污染指数的判定标准和方法以及由严控环境指标超标可直接判定为基地不符合无公害苹果生产基地的论断。     

发动机尾气射流特性研究

利用高速摄影仪实时拍摄发动机尾气的射流运动过程,通过Im age-Pro6.3专业图像处理软件,选择气体射流顶点为研究对象,根据自由射流理论,得到发动机尾气贯穿距离、射流锥角、射流速度随射流时间变化的规律。结果表明:尾气射流分为两个阶段,射流起始段和射流主体段。当发动机转速一定时,在整个射流过程中,射流贯穿距离随射流时间的增加而增加,射流锥角基本保持不变,射流速度随射流时间的增加而减小;当发动机转速提高时,射流贯穿距离、射流速度均有所减小,而射流锥角增大。在此基础上,确定了射流贯穿距离与射流速度之间的数学模型。     

广西西北部地区退化土地再造林项目人为净温室气体汇清除量预估

为了正确评估广西西北部地区退化土地再造林项目在应对气候变化中的作用,在全面收集项目区基础材料的基础上,结合大量的野外调查,估算了项目基准净温室气体汇清除量、实际净温室气体汇清除量以及泄漏,从而可较为精确地预估项目人为净温室气体汇清除量.预估结果,项目将在2008～2027年(20年)的首个计入期内产生1,405,447 t CO2 -e的tCER,年均70 272 t CO2-e.     

Root growth conditions in the topsoil as affected by tillage intensity

Many studies have reported impeded root growth in topsoil under reduced tillage or direct drilling, but few have quantified the effects on the least limiting water range for root growth. This study explored the effects of tillage intensity on critical soil physical conditions for root growth in the topsoil. Samples were taken from a 7-year tillage experiment on a Danish sandy loam at Foulum, Denmark (56°30′ N, 9°35′ E) in 2008. The main crop was spring barley followed by either dyer's woad (Isatis tinctoria L.) or fodder radish (Raphanus sativus L.) cover crops as subtreatment. The tillage treatments were direct drilling (D), harrowing 8-10 cm (H), and ploughing (P) to 20 cm depth. A chisel coulter drill was used in the H and D treatments and a traditional seed drill in the P treatment. Undisturbed soil cores were collected in November 2008 at soil field moisture capacity from the 4-8 and 12-16 cm depths.We estimated the critical aeration limit from either 10% air-filled porosity (ε_a) or relative gas diffusivity (D/D₀) of 0.005 or 0.02 and found a difference between the two methods. The critical limit of soil aeration was best assessed by measuring gas diffusivity directly. Root growth was limited by a high penetration resistance in the D and H soils (below tillage depth). Poor soil aeration did not appear to be a significant limiting factor for root growth for this sandy loam soil, irrespective of tillage treatment. The soil had a high macroporosity and D/D₀ exceeded 0.02 at field capacity. Fodder radish resulted in more macropores, higher gas diffusivity and lower pore tortuosity compared to dyer's woad. This was especially important for the H treatment where compaction was a significant problem at the lower depths of the arable layer (10-20 cm depth). Our results suggest that fodder radish could be a promising tool in the amelioration of soil compaction.     

Responses of leaf photosynthesis and plant growth to altered source–sink balance in a Japanese and a Dutch tomato cultivar

We investigated the effects of altered source/sink ratio by leaf or fruit pruning on leaf photosynthetic characteristics and whole-plant growth of ‘Momotaro York’, a Japanese cultivar, and ‘Dundee’, a Dutch cultivar and verified a hypothesis for sink-limitation of plant growth proposed by Tanaka and Fujita (1974). Plants were grown hydroponically with a high-wire system in a greenhouse for 11 weeks. Light-saturated photosynthesis of young, fully expanded leaves measured at atmospheric CO₂ partial pressure of 37 Pa and at an intercellular CO₂ partial pressure of 20 Pa was not influenced by alteration of source/sink ratio for either cultivar. Although soluble sugars were accumulated in leaves under high source/sink conditions, the amount of ribulose-1,5-bisphosphate carboxylase/oxygenase, a rate-limiting factor for CO₂-limited photosynthesis, was not affected by the altered source–sink balance. Net assimilation rate of a whole plant increased with decreasing source/sink ratio, but this can be accounted for by the changes in light interception per unit leaf area, without taking the source–sink relationship into consideration. It was concluded that the altered source/sink ratio did not change leaf photosynthetic capacity and the sink-limitation hypothesis cannot be applied to either cultivar under the conditions of the present study.     

应用顶空固相微萃取-气相色谱/质谱法分析杧果叶片挥发性物质成分

应用顶空固相微萃取法（HS-SPME）及气相色谱-质谱（GC/MSD）法进行本地种杧果叶片成分分析。结果共检测出68种挥发性成分,鉴定出其中的50个成分,含量占总挥发性组分的98.56%,其中主要成分为（n）-杜松萜烯（18.87%）、2,2,4,8-四甲基三环[5.3.1.0]8-十一烯（17.78%）、2,4,6-三甲基苯酚（12.94%）、,c-衣兰油烯（10.09%）、偄-杜松萜烯（-）-（8.14%）、香附子烯（5.64%）、（＋）-香橙烯（4.17%）等。分析结果从对本地种杧果叶片挥发性成分功能角度肯定其作为行道树的价值功效。     

不同发育时期椰子叶片精油的提取与成分分析

为明确引诱椰心叶甲[Brontispa longissima(Gestro)]取食的化学信息物质,利用同时蒸馏萃取法分别提取椰子(Cocos nucifera L.)的心叶、半展叶、老熟叶的精油,并采用气相色谱-质谱联用法对3者化学成分进行种类和含量的比较分析.结果表明,不同发育时期椰子叶片精油的主要成分为:2,3-二...     

水稻土中有机氯农药残留测定方法比较

研究国标方法对土壤中有机氯农药六六六、DDT 残留的测定结果,并与美国国家环境保护总局USEPA 8080 方法进行比较。结果表明,本研究条件下 USEPA 8080 方法对土壤中有机氯农药残留的测定结果显著高于国标方法,但 USEPA 8080 方法测定结果仅比国标方法测定结果高 14%,可以认为两种方法都适用于一般性的研究。     

Methane emissions from stems of Fraxinus mandshurica var. japonica trees in a floodplain forest

We measured methane (CH₄) emissions from the stem surfaces of mature Fraxinus mandshurica var. japonica trees in a floodplain forest. Flux measurements were conducted almost monthly from May to October 2005, and positive CH₄ fluxes were detected throughout the study period, including the leafless season. The mean CH₄ flux was 176 and 97 μg CH₄ m⁻² h⁻¹ at the lower (15 cm above the ground) and upper (70 cm above the ground) stem positions, respectively. The CH₄ concentration was lower in soil gas than in ambient air to a depth of at least 40 cm. One possible source of CH₄ emitted from the stems might be the dissolved CH₄ in groundwater; maximum concentrations were 10,000 times higher than atmospheric CH₄ concentrations. Our results suggest that CH₄ transport from the submerged soil layer to the atmosphere may occur through internal air spaces in tree bodies.