喀斯特森林近地表层覆盖对碳酸盐岩红土蒸发过程的影响

蒸发是西南喀斯特地区薄层土壤水分损失的主要途径,浅层土壤水分的存蓄对喀斯特地区农业生产和生态恢复至关重要。以西南喀斯特森林碳酸盐岩红土为研究对象,基于室内蒸渗试验设置4个苔藓生物量(0,0.32,0.64,0.95 kg/m~2)和3个松针生物量(0,0.32,0.64 kg/m~2)共12种处理,分析森林近地表层覆盖对碳酸盐岩红土蒸发过程及表层温度时空分布的影响规律,并对比3种蒸发模型(Black、Rose、空气动力学蒸发模型)在喀斯特森林碳酸盐岩红土的适用性。结果表明:苔藓和松针覆盖显著降低累积蒸发量和蒸发速率(P0.05),接种苔藓0.95 kg/m~2和覆盖松针0.64 kg/m~2处理比裸土累积蒸发量小36.9%;苔藓和松针导致土壤含水量显著增加(P0.05);苔藓和松针增加了表层土壤的平均温度,松针对土壤温度的提升作用强于苔藓;Black、Rose和空气动力学模型均能较好地模拟碳酸盐岩红土蒸发过程,Black蒸发模型的拟合精度高于Rose和空气动力学蒸发模型。研究结果能为西南喀斯特地区的水量平衡分析提供理论支撑并加强对喀斯特森林地表水文过程的认知。     

Soil carbon increases with long-term cattle stocking in northern temperate grasslands

Grassland management aimed at enhancing carbon (C) in soil is an important tool in mitigation of rising atmospheric CO₂, yet little is known of how grassland soil C changes with livestock stocking rate (SR). We relate soil organic and inorganic C mass (t ha⁻¹ to 60 cm depth) with cattle stocking over periods of 7–27 year for 32 paddocks distributed across nine community pastures in the mixed-grass prairie of Saskatchewan, Canada. Initial analysis comparing Akaike information criterion models showed that cattle SR explained a greater proportion of variance in soil C, particularly soil organic C, than rainfall. Soil organic C mass increased with cattle SR (R² = .293; p = .001), even when the latter was normalized to account for differences in vegetation composition and growing conditions among pastures. Normalized SR varied from 0.49 to 2.30 times recommended levels, over which SOC increased from 24.7 to 57.4 t ha⁻¹. Increases in soil organic C under greater stocking coincided with increased abundance of introduced vegetation, particularly the rhizomatous grass Poa pratensis. Inorganic soil C accounted for 34.6% of total soil C, being particularly large below 30 cm soil depth, but did not vary with stocking rate. These findings indicate that both organic and inorganic C are important pools of C in northern temperate grassland soils, with soil organic C positively associated with long-term cattle SR. Further studies are recommended to understand more fully the mechanisms regulating grazing impacts on soil C mass in northern temperate grasslands.     

喀斯特山区不同土地利用方式下石灰土化学风化特性

研究喀斯特山区不同土地利用方式（耕地、荒草地、退耕还草地和林草间作地）石灰土剖面化学风化特征，探讨矿质元素在石灰土剖面的分布、迁移和富集特征，从不同土地利用方式下土壤风化度，元素淋溶度、迁移度和残积度的角度分析土壤化学风化特征。结果表明：喀斯特山区石灰土剖面氧化物含量以SiO₂、Al₂O₃、Fe₂O₃为主，其他氧化物含量相对较低，均属于中等变异元素，SiO₂、Al₂O₃、MgO含量以荒草地较高，CaO、Na₂O含量以林草间作地较高，Fe₂O₃、MnO、P₂O₅、K₂O以耕地较高；研究区土壤处于中等化学风化阶段，富铝化程度弱，不同土地利用方式下荒草地土壤化学蚀变系数较强，林草间作地土壤富铝化程度较高；研究区土壤K、Na、Ca淋失严重，荒草地盐基离子淋失明显，林草间作地盐基离子淋失程度相对较低；土壤Fe、Al相对富集明显，残积程度高，林草间作地Al含量积累明显，退耕还草地Fe含量富集显著；实施“退耕—还草”等增加植被覆盖度的治理模式对土壤的保护作用显著。     

阜平表壳岩的地质特征

依据野外调查资料和室内化学分析，组建了阜平表壳岩的填图单元，单元分为阜平表壳岩上部和阜平表壳岩下部岩石。上部岩石原岩为沉积岩，属角闪岩相，无紫苏辉石，具有变余沉积层理和韵律构造，塑性变形差，从下到上可见片麻岩、浅粒岩、大理岩、斜长角闪岩的大韵律，角闪岩中还见小韵律；上部表壳岩的斜长角闪岩中SiO2、CaO、Mg0的含量均高于下部1％左右。下部岩石原岩为火山岩，见变余火山杏仁状构造和枕状构造，为麻粒岩相，含紫苏辉石，塑性变形强烈，原岩构造保留较少。上下岩石无直接接触关系，从下部岩石中测得Rb-Sr全岩同位素年龄为2700～2900Ma，属太古代岩石。     

Effect of drying methods on the discoloration of three major domestic softwood species in Korea

1 Introduction Three major softwood species in Korea are Japanese pine (Pinus densiflora), Korean pine (Pinus koraiensis) and larch (Larix leptolepis) which have been used for traditional buildings and furniture for a long period of time. They are easily discolored due to drying and UV irradiation. It has been observed that the discoloration varies with different drying methods and the extent of UV irradiation (Mottonen and Luostarinen, 2001; Kang, 2003). To prevent beech from discolorat…     

Crack formation due to weathering of radial and tangential sections of pine and spruce

The development of cracks and changes in appearance have been investigated on radial and tangential sections of pine (Pinus sylvestris L.) and spruce (Picea abies Karst.) after exposure outdoors for 61 months. The degradation of the sections has also been studied at the micro-level. The annual ring orientation was the most important factor affecting crack development on weathering. After 61 months of outdoor exposure, the tangential sections of spruce had 1.7-2.2 times greater mean total crack length per area unit than the corresponding radial sections. In pine, the total crack length per area unit on the tangential sections was 2.2-2.6 times greater than that on the radial sections. Tangential and radial sections show the same colour change as a result of weathering. Tangential sections have more and deeper cracks than radial surfaces. The cracks on the tangential sections occur frequently in both earlywood and latewood. On radial sections, cracks occur primarily at the annual ring borders, but to a certain extent also in the earlywood. Decomposition of the cell wall takes place in both radial and tangential cell walls, and cracks tend to follow the fibril orientation in the S2-layer of the cell wall. The radial cell wall of the earlywood has a large number of pits which are degraded at an early stage.     

Condensation reactions of phenolic resins V: cure-acceleration effects of propylene carbonate

Propylene carbonate (PC) is known as one of the cure accelerators for alkaline phenol–formaldehyde resins. To elucidate the cure-acceleration mechanisms, the effects of PC on the condensation reactions of monomeric hydroxymethylphenols (HMPs) were investigated and compared with those of PC hydrolysate, sodium bicarbonate (NaHCO₃) and ethyl formate. Immediately after the reaction started, PC, decomposing itself simultaneously, accelerated the formation of the ortho-para methylene-bonded dimer of 2,4,6-trihydroxymethylphenol. This effect of PC was very similar to that of ethyl formate. To the contrary, PC hydrolysate accelerated the formation of the para-para methylene-bonded dimer throughout the course of the reaction. This effect of PC hydrolysate was identical to that of NaHCO₃. These results indicate that PC increases the reactivity of the ortho-hydroxymethyl group, presumably through transesterification. On the other hand, NaHCO₃ is formed by the hydrolysis of PC or decomposition of the transesterified HMPs and it increases the reactivity of the para-hydroxymethyl group.     

Chemical analysis of the product in acid-catalyzed solvolysis of cellulose using polyethylene glycol and ethylene carbonate

Degradation and decomposition of cellulose were studied in an acid-catalyzed solvolysis treatment of biomass using polyethylene glycol (PEG) and ethylene carbonate (EC). The solvolysis reaction was followed by a typical reaction system of wood liquefaction that uses sulfuric acid catalyst at 140° or 150°C at atmospheric pressure. The methods of fractionation and chemical analysis of the degraded cellulose in the solvolyzed product are discussed. The solvolyzed product was separated into several fractions, and they were hydrolyzed to release glucose and levulinic acid to determine the quantity of glucosides and levulinates in the solvolysis product. The data clearly showed that the solvolysis reaction had the same mechanism when using PEG or EC. Degradation of cellulose leads to the formation of glucosides, which then decompose, resulting in a levulinic acid structure, and producing a water-insoluble fraction. The conversion rates of both glucosides and levulinates strongly depend on the reaction conditions of the solvolysis. In particular, EC promotes faster conversion of the reactions. The method discussed here is a chemical analytical technique for characterization of the products of wood liquefaction.     

火山岩和沸石填料BAF深度处理印染废水的效能比较

针对纺织印染行业水质不达标回用率低的问题,采用火山岩和沸石为填料的曝气生物滤池对纺织印染废水二级生化出水进行了深度处理,进行了两反应器出水效能的比较。研究表明:火山岩填料深度处理纺织印染废水的效能要高于沸石填料,建议气水比在10∶1左右,出水CODcr为36~48mg/L,出水色度35~55度,NH3-N浓度0.5~1.7mg/L,出水浊度范围0.9~3NTU。