次生植被下土壤活性有机碳组分季节动态研究

为了揭示不同类型植被下土壤有机碳及其活性组分季节动态变化及其特点，探讨不同的植被恢复模式对土壤有机碳组分的影响，分析影响土壤有机碳组分变化的因素，评估土壤有机活性有机碳组分参数在植被恢复过程中土壤质量监测的可靠性，为植被恢复及低效林改造技术提供理论依据。本研究选择岷江上游大沟流域的几种人工林（云杉林、油松林、华山松林、日本落叶松林）以及次生落叶阔叶灌丛下土壤，通过剖面机械分层取样，测定土壤总有机碳（TOC）和三种活性碳组分微生物碳（SMBC）、水溶性碳（WSOC）、易氧化碳（EOC）等来反映土壤变化特点。主要结果是： 1. 土壤有机碳含量平均在15.48~25.46 g kg-1之间在5月份时含量最低，随生长季的开始，有机碳含量逐渐增加，到9月份时含量达到最大值；由于新形成的凋落物不能被迅速分解利用补充土壤碳库，而原有碳库经历一个生长季的分解利用，因此，生长季末期即11月份的含量较小；土壤微生物碳含量平均在132.78~476.73mg kg-1之间，9月份和11月份含量都比较高；水溶性碳在生长季中逐步增大，含量在51.95~77.18 mg kg-1之间，到11月份时达到最大值；土壤易氧化碳平均含量在3.74~5.79g kg-1之间，含量最低值出现在5月份，但和其他碳组分不同的是其在7月份时含量较高。 2. 土壤有机碳及其活性碳组分大小关系为：TOC>EOC >SMBC>WSOC；比值约为300：70：5：1。 3. 土壤不同层次间比较，土壤碳指标都表现为随土壤深度增加而逐渐减小, 表层积聚作用明显。 4. 对土壤总有机碳量与活性碳组分以及活性碳之间进行了相关分析表明，土壤总有机碳含量与土壤微生物量碳、水溶性碳、易氧化碳之间的相关性均达到显著水平（P<0.05），有机碳总贮量很大程度上制约着土壤活性碳组分。土壤微生物量碳、水溶性碳、易氧化碳两两之间也都存在着显著相关关系（P<0.05），并随着不同植被类型或立地条件因子发生变化而变化。 5. 土壤有机碳及其活性组分与土壤养分状况之间的相关性分析发现，随着海拔、坡向或者植被类型的改变，其林下土壤有机碳及其活性组分与土壤养分的相关性也发生较大的变化。总体而言，岷江上游地区海拔、坡向、土壤自然含水量、植被盖度、凋落物厚度、土壤全N对次生林下土壤有机碳及其组分有重要影响。而AP、AK、C/N对土壤碳变化变化影响较小。 6. 通过不同海拔、坡向以及植被类型之间的综合比较分析发现，土壤微生物碳SMBC和水溶性碳WSOC比TOC和EOC更能敏感地反映出比较敏感的指示林下土壤质量的变化。 In order to reveal seasonal dynamics of soil labile organic carbon under different secondary vegetation, to analyze effect of different vegetation restoration pattern on soil organic carbon and its fractions, and to find the factors influencing changes in soil organic carbon and its fractions, further to estimate those parameters reliability for soil quality monitoring in the process of vegetation restoration. Soils were selected from several plantations, including Picea asperata Pinus tabulaeformis, Pinus armandii and Larix kaempferi and secondary shrub in Dagou Watershed of the upper reach of Minjiang River. The measurement of TOC, SMBC，WSOC and EOC were made, because these parameters can reflect change of soil characteristics. The major results are: 1. There were the lowest soil organic carbon and its labile fractions contents in May. At the time of growth initiation, they increased gradually and reached maximum in September. After that the soil organic carbon content decreased. Because current litter couldn’t be rapidly decomposed, and supplemented into carbon pool, while intrinsic carbon pool experienced decomposition and utilization of growth season, Which led a decrease in soil organic carbon content in November. Average value was 15.48~25.46 g kg-1; average SMBC content was 132.78~476.73mg kg-1.There were higher SMBC content in September and November as compared with other times; Water soluble organic carbon content increased from 51.95 mg kg-1 in May to 77.18 mg kg-1 in November; EOC content was lowest in May y. Average value was 3.74~5.79g kg-1. Differeing from other parameters of carbon fractions, EOC content was higher in July. 2. The content of soil organic carbon and its labile carbon fractions ranked as follows：TOC>EOC >SMBC>WSO，and ratio was about 300：70：5：1. 3. Consider as soil different layers，all of the parameters decreased gradually with increasing soil depth, thus displayed a significant accumulation in the surface layer soil. 4. Correlations coefficient analysis revealed that, TOC significantly correlated with SMBC, WSOC and EOC indicating total storage of organic carbon limited soil labile carbon fractions in great extent. On the other hand, there were significant correlations between SMBC，WSOC and EOC. But these relationships changed with vegetation types and/or environmental conditions. 5. The relationships between soil organic carbon and its labile fractions and soil nutrient traits changed with altitude，slope aspect and vegetations. Therefore our results suggested that altitude，slope aspect，soil natural water content，vegetation coverage, litter thickness and soil total nitrogen play a important role change in soil organic carbon and its fractions in upper reaches of Minjiang River. While AP、AK、C/N slightly influenced soil carbon. 6. Our results, on the other hand suggested that SMBC and WSOC are more sensitive to the change of altitudes, slope aspects, vegetation types than TOC and EOC, thus two parameters may be good index reflecting change of soil quality. These results provide insights into theoretical and technological evidences for the vegetation regeneration restoration and improvement of low-quality and benefit forest in the upper reaches of Minjiang River regions.

10-14岁超常儿童的亲社会行为特点及影响因素

Is prosocial behavior of supernormal children distinguished from normal children? Is there any difference between the supernormal children’s prosocial behavior from different educational placement? What are the mechanisms underlying the difference? The aim of this study was to examine these issues. With multiple methods of prosocial behavior, including other-rating, self-rating and hypothetical dilemma, we investigated the 10 to 14 year-old children. Firstly, the development of prosocial behavior and its relationship with prosocial behavior was examined. Secondly, we investigated the features of supernormal children’s prosocial behavior and analysed its difference with normal children. Finally, we tried to find the difference of supernormal children’s prosocial behaviour from different educational placement, and the mechanisms underlying the difference, such as social value orientation and peer relation. The results are as follows: 1)The altruistic and compliant prosocial tendency of 14 year-old children was obviously lower than those younger children. Intelligence was positively related with altruistic and emotional prosocial tendency for 10 year-olds, and with prosocial behaviour of peer nominated for 12 year-olds. 2)There was no significant difference of prosocial behaviour between supernormal and normal children. The peer nominated prosocial behaviour of 12 year-old supernormal children was higher than of 11 and 13 years old supernormal children. In addition, girls’ other-rating prosocial behaviour was significantly higher than boys’, but no gender difference was detected in the prosocial behaviour of self-rating and hypothetical dilemma. 3)With regard to the supernormal children’s prosocial behaviour in different educational placement, we found that the prosocial degree of the supernormal children of homogeneous groups was higher than that of heterogeneous groups in the role-change of ultimatum game. 4)The supernormal children from different educational placement had different social value orientation. More supernormal children of homogeneous groups belonged to the type of group enhancement, while more supernormal children of heterogeneous groups belonged to the type of equality. The types of social value orientation did not have impact on the supernormal children’s prosocial behaviour from different educational placement. 5)Peer relation moderated the impact of different educational placement on supernormal children’s prosocial behaviour.

Crystal-growth in floating zone with phase-change and thermosolutal convections

Floating zone crystal growth in microgravity environment is investigated numerically by a finite element method for semiconductor growth processing, which involves thermocapillary convection, phase change convection, thermal diffusion and solutal diffusion. The configurations of phase change interfaces and distributions of velocity, temperature and concentration fields are analyzed for typical conditions of pulling rates and segregation coefficients. The influence of phase change convection on the distribution of concentration is studied in detail. The results show that the thermocapillary convection plays an important role in mixing up the melt with dopant. The deformations of phase change interfaces by thermal convection-diffusion and pulling rods make larger variation of concentration field in comparison with the case of plane interfaces.

ROLE OF PHOSPHORUS CYCLING IN ALGAL METABOLISM AND ALGAL SUCCESSION IN LAKE DONGHU, CHINA

The role of phosphorus cycling in algal metabolism was studied in a shallow lake, Donghu, in Wuhan using the methods of measuring cell quota C, N and P, and calculating nutrients uptake rate by algal photosynthesis. The mean daily phosphorus uptake rate of phytoplankton varied between 0.04-0.11 and 0.027-0.053 g/m2/d in station I and station II respectively. The turnover time of phosphorus in phytoplankton metabolism ranged from 0.75-5.0 days during 1979-1986. The available P was 0.176 (+/- 0.156) g/m3 (mean +/- SD) in 1982 and 0.591 (+/- 0.24) g/m3 in 1986. The relationship between P/B ratio (Y) and TP (X: mg/l) was described by the following regression equation Y = 1.163 + 0.512logX (r = 0.731, P < 0.001). The dynamics of algal biomass and algal species succession were monitored as the indicators of environmental enrichment. The small-sized algae have replaced the blue-green algae as the dominant species during 1979-1986. The small-sized algae include Merismopedia glauca, Cryptomonas ovata, Cryptomonas erosa, several species Cyclotella. There has been drastic decrease in algal biomass and an obvious increase in P/B ratio. A nutrient competition hypothesis is proposed to explain the reason of the disappearance of blue-green algae bloom. The drastic change in algal size and the results in high P/B ratio (reaching a maximum mean daily ratio of 1.09 in 1986) may suggest a transition of algal species from K-selection to r-selection in Lake Donghu.

Role of Bi3+ ions for Er3+ ions efficient 1.54 mu m light emission in Er/Bi codoped SiO2 thin film prepared by sol-gel method

Er/Bi codoped SiO2 thin films were prepared by sol-gel method and spin-on technology with subsequent annealing process. The bismuth silicate crystal phase appeared at low annealing temperature while vanished as annealing temperature exceeded 1000 degrees C, characterized by X-ray diffraction, and Rutherford backscattering measurements well explained the structure change of the films, which was due to the decrease of bismuth concentration. Fine structures of the Er3+-related 1.54 mu m light emission (line width less than 7 nm) at room temperature was observed by photoluminescence (PL) measurement. The PL intensity at 1.54 gm reached maximum at 800 degrees C and decreased dramatically at 1000 degrees C. The PL dependent annealing temperature was studied and suggested a clear link with bismuth silicate phase. Excitation spectrum measurements further reveal the role of Bi3+ ions for Er3+ ions near infrared light emission. Through sol-gel method and thermal treatment, Bi3+ ions can provide a perfect environment for Er3+ ion light emission by forming Er-Bi-Si-O complex. Furthermore, energy transfer from Bi3+ ions to Er3+ ions is evidenced and found to be a more efficient way for Er3+ ions near infrared emission. This makes the Bi3+ ions doped material a promising application for future erbium-doped waveguide amplifier and infrared LED

Role of interactions in electronic structure of a two-electron quantum dot molecule

We have studied a two-electron quantum dot molecule in a magnetic field. The electron interaction is treated accurately by the direct diagonalization of the Hamiltonian matrix. We calculate two lowest energy levels of the two-electron quantum dot molecule in a magnetic field. Our results show that the electron interactions are significant, as they can change the total spin of the two-electron ground state of the system by adjusting the magnetic field between S = 0 and S = 1. The energy difference DeltaE between the lowest S = 0 and S = 1 states is shown as a function of the axial magnetic field. We found that the energy difference between the lowest S = 0 and S = 1 states in the strong-B S = 0 state varies linearly. Our results provide a possible realization for a qubit to be fabricated by current growth techniques.

Industrial development and land use/cover change and their effects on local environment: a case study of Changshu in eastern coastal China

The interactions among industrial development, land use/cover change (LUCC), and environmental effects in Changshu in the eastern coastal China were analyzed using high-resolution Landsat TM data in 1990, 1995, 2000, and 2006, socio-economic data and water environmental quality monitoring data from research institutes and governmental departments. Three phases of industrial development in Changshu were examined (i.e., the three periods of 1990 to 1995, 1995 to 2000, and 2000 to 2006). Besides industrial development and rapid urbanization, land use/cover in Changshu had changed drastically from 1990 to 2006. This change was characterized by major replacements of farmland by urban and rural settlements, artificial ponds, forested and constructed land. Industrialization, urbanization, agricultural structure adjustment, and rural housing construction were the major socio-economic driving forces of LUCC in Changshu. In addition, the annual value of ecosystem services in Changshu decreased slightly during 1990-2000, but increased significantly during 2000-2006. Nevertheless, the local environmental quality in Changshu, especially in rural areas, has not yet been improved significantly. Thus, this paper suggests an increased attention to fully realize the role of land supply in adjustment of environment-friendly industrial structure and urban-rural spatial restructuring, and translating the land management and environmental protection policies into an optimized industrial distribution and land-use pattern.

改革对教师工作生活质量影响的跨文化比较研究

From the organizational behavior point, this study initially explored how factors of educational changes influenced on teachers. This study adapted the questionnaire made up by Consortium for Cross-Culture Research in Education (CCCRE), by cooperating with other countries, interviewed 513 teachers in nine countries. The main results are as follows: 1. Factors of educational changes include: domain, origin, objective, teachers' role, and timetable. Comparative results show: More similarities than differences tend to be presented in five factors. The detail results are: in domain, it mainly involves teaching change and learning outcomes change; in origin, the educational change most teachers participated was initialed by government; in role, teachers more act as the implementer; in timetable, gradual development is the chief characteristic. 2. The domain of change, origin and teachers' role has a significant impact on the quality of worklife of teachers, but timetable of change has not. The further study about the influence of educational origin on the quality of worklife of teachers shows: Changes of teachers' time -using, professional development were significantly impacted by the origin of education, and there is a significant difference in the change of time-using among nine countries. 3. Change on students, change on teachers' relationship are two important factors to impact the teachers' evaluation about educational change. But the teachers' evaluation, teaching age and the change on relationship are valid factors to predicate teachers participate in next educational change. 4. Compared with the educational change of other eight countries, the change in school system management and the change in learning outcomes are more carried on in China. There is no significance about other factors between China and overall nine countries. In China, the educational change has a more positive impact on teachers' time-using and professional development, but professional development is also a important factor to impact teachers' evaluation on change; however there is a negative relationship between the Chinese teachers' evaluation and the teachers' participation in next change.

The role of Sn in Pt-Sn/CeO2 catalysts for the complete oxidation of ethanol

The structural features and catalytic properties of Pt-Sn/CeO2 catalysts prepared by modified polyol method were extensively investigated for the complete oxidation of ethanol. CO chemisorption, TPR, DTA and XPS measurements identically indicated that the electronic configuration of Pt by Sn as well as the formation of PtSn alloy were the key factors in determining the nature of the active sites, A strong Pt/Sn atomic ratio dependence of catalytic perfortmances was observed. which was explained in terms of the change., in the Surface structure of metal phases and the electronic Pt-Sn interaction. (c) 2005 Elsevier B.V. All rights reserved.