Conversion of Bioethanol to Olefins over ZrO_(2) Catalyst

Ethylene and 1,3-butadiene are important organic chemical raw materials.Petroleum hydrocarbon cracking is the most widely used method for ethylene fabrication worldwide.In this study,the use of a ZrO_(2) catalyst,which can be easily synthesized,for the efficient conversion of bioethanol to ethylene and 1,3-butadiene was analyzed.X-ray diffraction,transmission electron microscopy,temperature-programmed desorption,and Fouriertransform infrared spectroscopy analyses were used to evaluate the surface properties of ZrO_(2).The selectivity of ZrO_(2) toward ethylene and 1,3-butadiene was as high as 98.2%.Catalyst selectivity toward dehydration or dehydrogenation products depends on the nature of the weak acid-base catalytic sites,whereas high-strength base and intermediate-strength acid catalytic sites selectively yield ethylene.

土壤动物群落空间格局和构建机制研究进展

群落空间格局和构建机制一直是生态学研究的核心内容。在生物多样性严重丧失的背景下,揭示群落空间格局及其构建机制,有助于深刻理解生物多样性丧失的原因,更有助于应对生物多样性保护等重大生态环境问题。然而,陆地生态系统的研究多集中于地上生物群落,对地下生态系统,尤其是土壤动物空间格局和构建机制的研究尚不充分。事实上,土壤动物多样性是全球生物多样性的关键组成之一,是地下生态系统结构和功能维持的重要部分。对土壤动物空间格局和构建机制的研究,能明确不同空间尺度条件下土壤动物多样性的维持机制。土壤动物群落常在多种空间尺度形成复杂的空间分布格局,因此,本文首先介绍了不同空间尺度主要土壤动物群落的空间自相关性特征,阐述了土壤动物群落斑块和孔隙镶嵌分布的复杂空间格局。继而阐明这种空间格局主要受生物间作用、环境过滤和随机扩散的调控,并说明这三个过程对土壤动物群落的调控能力和作用方式。作者提出,这三个过程仍是今后土壤动物群落空间格局和构建机制研究的重点内容,需要进一步加强以土壤动物为研究对象的群落构建理论的验证和发展。我国土壤动物群落空间格局和构建机制起步较晚,希望本文能够促进我国土壤动物生态学相关领域的研究。

中国农田土壤动物长期监测样地科学调查监测的实施方法

我国农田土壤动物面临严峻的多样性丧失问题,建设监测样地并开展长期监测是解决该问题的重要途径,但至今国内外仍缺乏农田土壤动物长期监测样地科学调查监测的实施方法。依据BCI 50 ha大型固定样地建设规范,参照我国已建成的森林和农田土壤动物大型固定样地监测经验,本文提出了农田土壤动物长期监测样地科学调查监测的实施方法。首先,需要明确科学问题,确定科学调查监测应遵守的基本原则。其次,需要规范长期调查监测涉及的专业术语,依据研究目的和实际情况选择地点和样地,参照建设规范和农田特征建立农田土壤动物大型固定样地。第三,以研究农田土壤动物多样性为核心,揭示土壤动物在农田生态系统健康和功能中的作用,有选择性地开展4类27项科学指标的长期监测工作,要求按照统一的、规范化的工作流程开展野外调查和室内实验。最后,要科学规范地完成标本的鉴定描述和保存保管,研发体现农田土壤动物特征的数据库和管理信息系统。希望本文的研究结果能推动我国乃至世界范围的规范化样地建设和标准化网络监测,为我国农田土壤动物评估与保护提供长期可靠的数据支撑。

Factors that affect the assembly of ground-dwelling beetles at small scales in primary mixed broadleaved-Korean pine forests in north-east China

Disentangling the relative roles of environmental and spatial processes in community assembly is a major task of community ecology.It is necessary to uncover this question at multiple spatial scales;however,the relative importance of spatial and environmental processes on ground-dwelling beetle assembly at a small scale is still unclear.Based on two permanent plots(each 300 m)located in primary mixed broadleaved-Korean pine forests,the topographic,soil,and plant factors were collected,and the spatial variables(MEMs,distancebased Moran’s eigenvector maps)were calculated.A redundancy analysis(RDA)was used to evaluate the influence of topographic,soil,and plant variables on ground-dwelling beetle compositions.A variation partitioning analysis was used to quantify the relative contributions of environmental and spatial processes on the assembly of ground-dwelling beetles.The results of the RDA reported that the soil,plant,and topographic variables affected Staphylinidae and Silphidae beetle compositions in both plots.According to the results of variation partitioning,pure soil and plant variables were important for the assembly of Silphidae beetles in the LS plot.The contributions of pure topographic,soil,and plant variables were significantly lower than those of pure spatial variables.The contributions of pure spatial variables were significant for the assembly of Staphylinidae and Silphidae beetles in both plots.In addition,the relative importance of environmental and spatial processes was not significantly changed after including more environmental variables and the unexplained variations.Finally,this study suggests that both spatial and environmental variables are important for the assembly of ground-dwelling beetle communities,while pure spatial variables are more important than pure environmental variables at a small scale(300 m).

Contrasting beta diversity of spiders,carabids,and ants at local and regional scales in a black soil region,northeast China

Understanding the factors determining the formation of each community and metacommunity across a landscape is one of the most important ideas in soil animal ecology.However,the variables and parameters that shape soil arthropod communities in agroecosystems have not been resolved.These arthropods can serve as important bioindicators of field management and its sustainability.We sampled five com plantations in each of three locations across a region spanning 600 km to come up with these determinants of the community structure of ground-dwelling spiders(Erigoninae:Araneae),carabids(Coleoptara:Carabidae),and ants(Hymenoptera:Formicidae).The analysis of the five fields within each of the three locations represent our local-scale samples,while the comparisons of the 15 sites across all three locations represent the regional scale samples.We tested the hypothesis that in the models we sampled,environmental/soil variables would drivecommunity assembly locally(within location comparisons),but at the regional scale(between location comparisons),climatic and spatial variables would drive metacommunity assembly.The outcomes of our study showed distinct communities at each of the three locations when compared across regions but locally,fields were similar in species composition,as expected.Locally,spatial variables were important but not soil variables,regulated species richness and abundance.Turnover contributed more than nestedness to explain the biodiversity of spiders,carabids,and ants at both the local and regional scales.Neither purely climate variables,nor purely soil or spatial variables were significant enough explanations for the regional scale arthropod community composition.However,spatially structured environmental factors contributed most to explain the patterns supporting our hypothesis.We conclude that biodiversity in this agroecosystem area can be promoted by a mosaic of land uses being encouraged to increase landscape complexity at the regional scale.