Fish-mediated changes in bacterioplankton community composition: an in situ mesocosm experiment

We characterized variations in bacterioplankton community composition(BCC) in mesocosms subject to three different treatments. Two groups contained fish(group one: Cyprinus carpio; group two: Hypophthalmichthys molitrix); and group three, the untreated mesocosm, was the control. Samples were taken seven times over a 49-d period, and BCC was analyzed by PCR-denaturing gradient gel electrophoresis(DGGE) and real-time quantitative PCR(q PCR). Results revealed that introduction of C. carpio and H. molitrix had a remarkable impact on the composition of bacterioplankton communities, and the BCC was significantly diff erent between each treatment. Sequencing of DGGE bands revealed that the bacterioplankton community in the different treatment groups was consistent at a taxonomic level, but differed in its abundance. H. molitrix promoted the richness of Alphaproteobacteria and Actinobacteria, while more bands affiliated to Cyanobacteria were detected in C. carpio mesocosms. The redundancy analysis(RDA) result demonstrated that the BCC was closely related to the bottom-up(total phosphorus, chlorophyll a, phytoplankton biomass) and top-down forces(biomass of copepods and cladocera) in C. carpio and control mesocosms, respectively. We found no evidence for top-down regulation of BCC by zooplankton in H. molitrix mesocosms, while grazing by protozoa(heterotrophic nanoflagellates, ciliates) became the major way to regulate BCC. Total bacterioplankton abundances were significantly higher in C. carpio mesocosms because of high nutrient concentration and suspended solids. Our study provided insights into the relationship between fish and bacterioplankton at species level, leading to a deep understanding of the function of the microbial loop and the aquatic ecosystem.     

利用VB进行MAPGIS二次开发建立房屋信息管理系统

介绍基于ＭＡＰＧＩＳ平台利用ＶＢ语言实现信息管理的二次开发中的关键技术及建立房屋信息数据的注意问题。     

“Krige”空间内插技术在地理学中的应用

称为“Krige”技术的内插稀疏观测资料的随机方法是Matheron(1970年)提出的,D.R.Krige首先将这一方法应用于找矿上,因而命名于“Krige”技术。本文首先定义和说明了空间协方差曲线,基于无偏估计和最优原理导出了“Krige”内插权重系数的代数方程组,最后给出实例说明该方法如何应用到地理学和水文学中。     

吹填粉细砂的无填料振冲密实试验与工程应用

对长江下游河漫滩地新吹填的松散粉细砂,通过原位监测仪器和跟踪检测,进行了无填料振冲试验、施工技术开发和设计应用。研究了无填料振冲过程中桩周土的超静孔压变化与振冲有效范围,比较了振冲密实前、后桩周土强度变化。针对施工跟踪检测中发现的桩身土局部欠密实问题,分析了缺陷产生原因,提出了解决措施。结果表明,目前规范认为应加填料振冲处理的各种松散粉细砂,只要试验方法得当,及时发现振冲中可能出现的问题并予以解决,吹填粉细砂的无填料振冲密实法是可以大面积应用的。工程试验后提出的振冲设计参数、施工工艺参数和质量控制方法,最终检测显示,工程桩各项指标达到堆场使用要求。     

遥感技术在环境监测中的应用探讨

环境监测作为环境污染防治的重要手段之一,在环境保护领域发挥着日益重要的作用,随着航空遥感和卫星遥感技术的发展,它的高效、即时更新、连续性好等优势为环境监测工作者所认识,在此主要介绍了遥感技术的主要特点,说明了遥感技术在环境监测领域中的应用,着重阐述了高光谱遥感技术在环境监测中新的发展趋势,最后提出了遥感技术在环境监测中的发展方向。     

MCSs移出青藏高原规律的可视化表达与知识发现

为了客观揭示青藏高原上中尺度对流系统(Mesoscale Convective Systems，MCSs)的演变规律，尤其是它向东移出高原的条件，采用卫星红外影像运动目标计算机自动识别与跟踪技术，提取了高原上夏季MCSs的大小、强度、生命史、形状及分布等空间特征，并将MCSs的空间特征与青藏高原HLAFS资料相关联，建立了MCSs时空数据库。运用面向时空数据挖掘的相关分析法、关联规则及决策树法，求解MCSs东移传播出高原与其周边环境物理场之间的关系，进而建立了400hPa和500hPa两个层次上影响MCSs移出高原的环境物理场的可视化概略模型图。从模型图中发现：在400hPa上，移出高原且方向向东的MCSs主要决定于等压面高度、散度和涡度场，等压面高度变化呈南北向；而在500hPa上，等压面高度和K指数场是影响。MCSs移出高原的主要因素，K指数变化呈西东走势。模型图初步揭示了MCSs移出青藏高原的规律。