Seasonal changes in the water use strategies of three co‐occurring desert shrubs

Water is a major limiting factor in desert ecosystems. In order to learn how plants cope with changes in water resources over time and space, it is important to understand plant–water relations in desert region. Using the oxygen isotopic tracing method, our study clarified the seasonal changes in the water use strategies of three co‐occurring desert shrubs. During the 2012 growing season, δ¹⁸O values were measured for xylem sap, the soil water in different soil layers between 0 and 300 cm depth and groundwater. Based on the similarities in δ¹⁸O values for the soil water in each layer, three potential water sources were identified: shallow soil water, middle soil water and deep soil water. Then we calculated the percentage utilization of potential water sources by each species in each season using the linear mixing model. The results showed that the δ¹⁸O values of the three species showed a clear seasonal pattern. Reaumuria songarica used shallow soil water when shallow layer was relatively wet in spring, but mostly took up middle soil water in summer and autumn. Nitraria tangutorum mainly utilized shallow and middle soil water in spring, but mostly absorbed deep soil water in summer and autumn. Tamarix ramosissima utilized the three water sources evenly in spring and primarily relied on deep soil water in summer and autumn. R. songarica and N. tangutorum responded quickly to large rainfall pulses during droughts. Differential root systems of the three species resulted in different seasonal water use strategies when the three competed for water. Copyright © 2013 John Wiley & Sons, Ltd.     

压入硬度的修正方法──根据硬度和塑性系数估算破岩比功

通过分析压入硬度和破岩比功的关系,得出比功更能综合反映岩石的破碎难易程度的结论。为简化比功的测定方法,提出根据压入硬度、塑性系数及破碎坑体积扩大率来估算比功的方法,推导出比功的计算公式,并对比功的计算值和实测值进行了对比,具有一定应用价值。     

中国-东盟自由贸易区下中越边境区位优势再造

针对广西与云南两省区对越南贸易比重下滑的现象,提出中越边境区位优势是凸显还是凹陷、递增还是递减的问题;从边境区位优势可再造的角度,用SWOT分析“10＋1”自贸区下中越边境区位的优势、劣势、机遇与挑战,建议通过定期举办“中越边境2＋6省区论坛”、设立跨境工业园区与边境跨国经济合作区、共建区域经贸服务平台、建设区域创新系统、开展中越八角香料及中草药经济带等边境区域合作,扩大合作规模,再造区位优势。     

基于空间数据库的多媒体图形查询信息系统研究——以苏州河环境综合整治为例

本文介绍作者自行开发的GIS软件系统———基于空间数据库的多媒体图形查询信息系统的内容、结构和功能 ,以及在环境规划管理方面的应用。阐明了系统可满足决策管理层和公共信息发布层等不同层次的应用需求 ,对环境工程项目的规划管理可作为示范和借鉴。说明本系统除具有一般GIS系统所具有的功能外 ,还把现代多媒体技术和GIS空间数据库技术结合起来 ,实现了在空间数据基础上的多媒体信息查询 ,丰富了GIS中属性数据查询的内容 ,提高了地图的可视性。详细介绍了一种地理信息系统的空间分析方法———包含分析的算法和在本系统中的具体应用———按多边形区域进行空间相关性关系查询。     

Decadal‐scale gravel beach evolution on a tectonically‐uplifting coast: Wellington,New Zealand

Uplift of the shoreline in tectonically‐active areas can have a profound influence on geomorphology changing the entire process dynamics of the coast as the landforms are removed from the influence of the sea. Over decadal timescales it is possible for the landforms to return to their pre‐earthquake condition and this paper examines the re‐establishment of mixed sand and gravel beaches on the coast of Wellington, New Zealand, subsequent to an uplift event in 1855. Over 60 topographic profiles were surveyed, seven sets of aerial photographs from a 67 year period were mapped and sediment size analyses conducted in order to quantify the nature of beach change following uplift, and associated relative sea level fall. These data were supported by surveys using ground penetrating radar. It is found that uplift raised the gravel beaches out of the swash zone thereby removing them from the littoral zone. Intertidal rocky reefs which occur between each embayment were also uplifted during the same event and completely interrupted the longshore transport system. Continued input of gravel material to the littoral zone allowed beaches to re‐establish sequentially along the coast as each embayment was infilled with sediment. This reconnection of the embayments with the longshore drift system is associated with the beach planform being initially drift dominated during infill but then switching to swash alignment once the embayment becomes infilled. This has resulted in shoreline accretion of over 100 m in some places, at rates of up to 4 m/yr, covering shore protection works built in the past few decades. The ability of the shore to adjust back to its pre‐uplift condition appears to be a function of the accommodation space created during uplift and the rate of sediment supply. Copyright © 2012 John Wiley & Sons, Ltd.     

腐泥煤和腐植煤生物标志物色谱对比

从代表低、中、高三个煤化阶段的三对共生样品的可溶组分的色谱质谱(GC/MS)联机分析的结果看,饱和烃和芳烃的组成,在腐泥煤和腐植煤两个变质系列中始终存在明显差异。比如腐泥煤的碳数分布较宽,OEP值始终都低于共生腐植煤;所含的芳烃种类少,数量也少,有些大大低于共生的腐植煤有些腐植煤中的标志物在腐泥煤中找不到。     

贝藻混养技术在我国海水养殖中的应用与研究

贝藻混养技术是一种极有发展前途的养殖方式 ,对改善目前我国海水养殖中存在的水质污染严重、养殖品种生长缓慢等问题 ,具有十分积极的作用。从几十年来我国海水养殖中贝藻混养技术的发展、应用及研究现状等几个方面 ,综合论述了这一技术的优点和发展动态 ,为我国海水养殖业的进一步健康发展提供参考