Drying and anatomical characteristics of sugi wood attacked by bacteria during pond storage

Seven species of bacteria were isolated and identified from ponded sugi (Cryptomeria japonica D. Don) logs, and six species showed potent wood-degrading activities. To evaluate the effects of these isolated bacteria on the drying and anatomical characteristics of wood, small fresh blocks of sugi were immersed in water suspensions containing bacteria for 1–7 months. The permeability and drying properties were evidently improved. Most of the encrusting substances adhering to the cell lumens and the pit chambers were removed, and the pit membranes were destroyed. These anatomical changes due to bacterial activity were assumed to improve the permeability of sugi wood.Part of this report was presented at the 40^th annual meeting of the Japan Wood Research Society, Tsukuba, April 1990; the 41^st annual meeting of the Japan Wood Research Society, Matsue, April 1991; and the IUFRO XX World Congress, Tampere, August 1995     

ELECTRE--Ⅱ法在企业资本营运中的应用

市场经济中的资本营运是一个敏感的、决定企业生死存亡的复杂决策．资本金运行的正增量收益取决于一系列正确的决策．生产前期的多目标决策是其中一个重要环节,使用ＥＬＥＣＴＲＥ———Ⅱ法对其作出决策分析能较好地降低误差,更好地反映真实结果．     

The effect of preferential flow on the short and long-term spatial distribution of surface applied solutes in a structured soil

We measured the lateral distribution of Br in a well-structured soil (clayey, kaolinitic, thermic Typic Kanhapludults) over a period of 40 days following a leaching event with Br-tagged water (Event-1) and the subsequent vertical transport of solute that occurred following a second leaching event (Event-2). The objectives were to determine the time required for solutes to become uniformly distributed laterally after Event-1, and the effect that degree of spatial distribution had on the subsequent vertical movement induced by Event-2. Six field plots, 1.2 by 1.2 m, were exposed to Event-1. Three of the plots were sampled 1, 5, or 40 days later. The three remaining plots were exposed to Event-2 either 1, 5, or 40 days following Event-1 and they were sampled the day following Event-2. A total of 319 samples were taken from a 38.5 by 38.5 cm area in the center of each plot at each of five depths ranging from 5 to 60 cm. Bromide was practically uniformly distributed in the surface layer immediately following Event-1, as indicated by a coefficient of variation (CV) of 25% among the 319 samples, but became progressively more non-uniformly distributed as depth increased. At 60 cm, the CV had increased to 240%. The longer we delayed sampling following Event-1, the more uniform was the lateral distribution of Br. During the 40 days following Event-1, Br became practically uniformly distributed across all layers, and the center of mass moved from 8 to 16 cm below the surface. Event-2 caused Br to move deeper within the soil profile when it occurred the day following Event-1 than when it occurred later, but because drainage occurred during the 40-day delay, the center of Br mass was located 26–27 cm below the surface after Event-2 regardless of the delay time.     

Differential host residence of adult cryptomeria bark borer,Semanotus japonicus Lacordaire (Coleoptera: Cerambycidae), in relation to tree size of Japanese cedar,Cryptomeria japonica D. Don

To understand factors involved in tree-size dependent vulnerability ofCryptomeria japonica to damage bySemanotus japonicus, residence of adultSemanotus japonicus on host trees was assessed in twoCryptomeria japonica stands, using band trap method and mark-recapture techniques. Adult capture distributions among trees were analyzed in relation to diameter size of each tree. Female adults consistently exhibited more frequent residence on larger trees, under different field conditions. Females that made inter-tree movements preferentially chose larger trees as their destinations. Frequent residence by females on large trees was associated with high productivity of progeny adults. Male adults were also more frequently resident on larger trees. These results suggest that tree-size dependent oviposition accounts for the tree-size dependent vulnerability ofCryptomeria japonica to damage bySemanotus japonicus. Possible causes underlying the differential host residence of adultSemanotus japonicus are discussed.     

榆林沙区无排灌条件盐碱地水盐运动规律研究

研究分析了榆林沙区无排灌条件盐碱地水盐运动的时空变化,其水盐运行主要是随着季节、地形等因素的变化而变化。干旱季节,由于蒸发强烈,盐分随着水分的蒸发,处于上行状态,为积盐期;到了雨季,盐分又随着水分的下渗,处于下行状态,为淋溶期;由于地形的起伏变化,水盐运动也随着变化,随着地势的降低,地下水位升高,盐分含量增加。通过对榆林沙区无排灌条件盐碱地水盐运动的研究,为改良利用榆林沙区无排灌条件盐碱地提供了理论依据,奠定了一定的基础。     

Novel lysimeter techniques — a basis for the improved investigation of water,gas, and solute transport in soils

For many years lysimeters have been proven to be effective tools in assessing and predicting the effects of current land use and future land use changes in catchment areas on both water and solute balances. Although due to the diverse aspects of mass transport modelling, many different types of lysimeters exist, water and solute balances are by no means fully understood, especially in post‐mining areas. To tackle this problem, a new piece of equipment has been developed which enables the actual weight of a lysimeter to be precisely measured. The newly designed device, which has been used for one of the experiments described in this paper, permits the weighing of for example a 2 m³ lysimeter vessel with an accuracy down to 30 g. The second newly developed appliance presented here is the GAMS (Gas‐Migration‐Simulator). Basically comparable to a lysimeter, the difference is that the GAMS allows the detailed investigation of soil‐gas migration processes and their dependence on parameters like the diffusion coefficient and the gas permeability of the soil, alterations of the groundwater level and on various external influences such as changes of the actual meteorological conditions. These two newly developed techniques are described in this paper, and their respective suitability is demonstrated on the basis of data sets recorded during initial experiments.     

土壤结构调理剂PAM对复垦铁尾矿砂物理性状的影响

聚丙烯酰胺(polyacrylamide,PAM)是一种常见的土壤结构调理剂,但在尾矿复垦中却少有应用。该文通过室内土柱模拟试验,采用干混法在铁尾矿砂中加入PAM,设置0%(对照)、0.05%、0.10%和0.20%共4种质量浓度PAM,观测PAM对铁尾矿砂物理性状的影响。结果表明:1)除总孔隙度之外,对照与混合PAM尾矿砂的容重、毛管孔度和毛管持水量差异显著(P0.05)。2)随着尾矿砂毛管水上升高度增加,PAM质量浓度越大,含水率下降的趋势越缓慢,但含水率的变异性却越大,变异系数从1.22%(10 cm)增大到7.13%(40 cm)。3)PAM会极显著抑制尾矿砂毛管水上升高度(P0.01)但PAM质量浓度不同,抑制程度不同。据此可将上升曲线分为3个阶段:第1阶段,0~5 min,上升高度相似阶段;第2阶段6~25 min,上升高度分异阶段;第3阶段30~420 min,上升高度变化规律相对稳定阶段。毛管水上升高度随时间变化呈现幂函数增加趋势,上升速率随时间变化呈现幂函数减小趋势。4)在自然通风状态下,72小时内不同PAM质量浓度尾矿砂的含水率均持续降低,纯尾矿砂含水率的降低幅度最大,从37.53%减少到35.60%;PAM质量浓度为0.20%的尾矿砂含水率降低幅度最小,从37.40%减少到36.67%。因此,PAM的合理使用能够有效改善尾矿砂的物理性状和水分运移,为无土区的植被恢复创造适宜的生长条件。     

微润灌溉技术研究进展及展望

[目的]对近年来国内外关于微润灌溉技术的研究成果进行综述,探讨微润灌溉的未来研究方向,为微润灌溉制度和灌溉参数的制定及该节水技术的推广提供依据。[方法]总结微润灌溉的发展历程和应用现状,微润灌溉条件下土壤水分运动规律,微润灌溉对作物生长的影响,并分析微润灌溉技术的不足之处。[结果]微润灌溉是一种新型地下灌溉技术,以连续灌溉方式不间断地向作物根系供应适量水分,使植物吸水过程与田间灌溉过程具有同步性,灌水量与植物耗水量相匹配,实现无胁迫灌溉,改善作物品质和产量。该技术已成为国际领先的仿生型连续灌溉系统,在干旱半干旱地区具有广阔的应用前景。[结论]今后应加强的研究领域主要包括:微润灌溉对土壤养分运移的影响;微润灌溉对不同种植模式作物生长的影响;微润灌溉对农田生态系统温室气体排放的影响。     

圆周电磁振动下单粒玉米种子运动特性分析

针对基于圆周电磁振动的玉米种子定向排序输送装置的优化缺乏理论指导的问题,该文以角振幅θ0、玉米种子所处圆周半径r以及正向圆周运动角速度θ?为主要参数,采用柱坐标系对圆周电磁振动下单粒玉米种子的运动特性进行了理论研究和试验分析,得到以下结果:1)玉米种子相对运动特性表现为:其正向圆周运动、反向圆周运动、抛掷运动和离心运动都有着与之对应的临界角振幅(θ01、θ02、θ03和θ04),其中θ01θ02θ03,θ03为0.012 9 rad不变,θ01、θ02和θ04随玉米种子所处圆周半径r的增大而减小;2)玉米种子自身运动特性表现为:只有当胚面朝上时,玉米种子才表现出通过自身运动使尖端朝向与圆周运动切线方向一致的规律;3)圆周电磁振动器的最佳工作角振幅为0.008 rad,此时无论胚面朝上或朝下,玉米种子正向圆周运动角速度θ?均达到最大(胚面朝上时4.15°/s、胚面朝下时4.03°/s)。该研究丰富了圆周电磁振动下物料的运动理论,为玉米种子定向排序输送装置的优化提供了理论基础。     

脱硫石膏施用下宁夏盐化碱土水盐运移特征

为定量描述脱硫石膏施用下盐化碱土土壤剖面盐分与淋洗水量的关系,通过室内土柱淋洗试验开展了脱硫石膏施用下不同淋洗水量对宁夏盐化碱土水盐运移影响的研究。结果表明:施用脱硫石膏对增加水分入渗和降低0—20cm土层土壤pH、盐分含量产生了积极影响,土壤脱盐率84.39%~95.41%,但较大水量的淋洗有可能会加剧土壤碱化。连续淋洗条件下,最大脱盐深度位于60—80cm土层。脱硫石膏施用下,0—20cm土层Cl~-、Na~+溶脱率随淋洗水量的增加变化不大,低淋洗水量下,SO_4~(2-)溶脱率低于Na~+和Cl~-,高淋洗水量下,3种离子溶脱率接近;20—40cm土层主要盐分离子溶脱率由大到小依次为Cl~-、SO_4~(2-)、Na~+,各离子脱盐率随淋洗水量的增加先增加较快后趋于平缓。当淋洗水量达到60cm时,SO_4~(2-)和Na~+在80—100cm土层累积,Cl~-则运移至100cm土层以下。