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本文通过一个实例,总结了在粉砂地层中,怎样正确合理地使用活塞法进行洗井,对用活塞法进行洗井,具有一定的指导意义。 相似文献
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Phytoplankton and environmental variables were measured monthly from July 2009 to August 2011 in the Maixi River from the estuary to Baihua Reservoir in the Maotiao River catchment,southwestern China,to understand phytoplankton community structure and environmental factors.The relationship between phytoplankton community structure and environmental factors including hydrological,meteorological,physical,and chemical variables were explored using multivariate analysis.A total of 81 taxa of phytoplankton were identified,which were mainly composed of chlorophyta,bacillariophyta,and cyanobacteria.The phytoplankton community was dominated by Pseudanabaena limnetica during summer and fall and by Cyclotella meneghiniana during winter and spring.The abundance of phytoplankton ranged from 0.24×104 cells/L to 33.45×106 cells/L,with the minimum occurring during February 2010 and the maximum during July 2009.The phytoplankton community was dominated mainly by cyanobacteria from April to September,and by bacillariophyta and pyrrophyta from October to March.Canonical correspondence analysis showed that temperature,pH values,and orthophosphate were the most important driving factors regulating the composition and dynamics of the phytoplankton community in the estuary.Cyanobacteria and euglenophyta abundance and biomass were affected mainly by temperature and pH values,while most chlorophyta and bacillariophyta were influenced by the concentrations of nutrients. 相似文献
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天津市浅层地下咸水资源利用及其环境影响评价 总被引:6,自引:1,他引:6
天津市浅层地下咸水大面积的存在制约着天津市工农业的发展与人民生活水平的提高。利用浅层地下咸水作为城市工业与生活用水既可以解决城市供水不足 ,又可以达到根治盐碱、抗涝、改良地下水的综合效益。但是不合理利用地下水可能引起地面沉降、海水入侵等多种环境危害。本文分析了浅层地下水大规模利用及其可能带来的环境危害与防治措施 相似文献
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基于双冗余以太网通信的气象实时观测数据采集网络传输系统的设计与实现 总被引:1,自引:0,他引:1
随着以太网技术应用的日趋成熟,在海洋和大气观测领域,人们希望对传统不具备网络通讯能力的观测仪器进行智能化和网络节点化改造。设计和实现了一套气象实时观测数据采集与网络传输系统。该系统采用基于ARM的嵌入式系统集成设计方案,实现了对外部传感器实时观测数据的采集和以太网通信。作为多级网络系统中的一个网络节点,该采集传输系统采用双冗余以太网通信接口设计,使系统中的双路以太网在一路局部故障或线路受损时可以自动冗余切换。这一设计特点大幅提高了作为网络节点的数据采集传输系统在与外部其他设备通信时数据传输的可靠性。通过在以太网条件下,网络闭环控制运行试验等测试,证明所开发的气象实时观测数据采集网络传输系统运行稳定可靠,双冗余以太网接口切换正常,数据采集传输及时准确,可完全满足实际应用的需要。 相似文献
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