土壤水盐运移模型研究进展及展望

回顾了国内外土壤水盐运移模型的发展历程,根据土壤水盐运移模型构成的原理和发展趋势,将土壤水盐运移模型分为水盐平衡模型、物理模型和系统模型。借助国内外文献对已有模型的原理和应用进行了介绍,并对存在的问题进行了分析;展望了新形势下土壤水盐运移模型的未来发展趋势和研究重点,旨在为今后土壤水盐运移模型研究提供新的思路。     

基于地名志的东北历史时期土地利用变化研究——以吉林省镇赉县为例

研究历史时期的土地利用与土地覆被变化,对于人类的生产活动有着重要的借鉴意义。本文以吉林省镇赉县为例,探讨了地名志等历史资料在确定东北地区大规模开发利用初始年限研究中的应用,并结合重分类、重心转移分析、叠加分析方法,分析了镇赉县地名志等史料记载的土地开发利用特征。结果表明:在康熙年间和1853年,镇赉县先后有过有记载的定居后小范围开垦活动,而直到1875年开始持续的土地开垦利用,此前镇赉县基本上处于自然状态。在技术手段不发达的早期,村屯的演变过程与土地开发利用过程是相辅相成的,因此,从村屯演变特征来看,1907-1912年期间土地开发利用最为突出;到1975年时,镇赉县村屯格局基本形成,而此时的土地开发利用活动已由个人行为转变为集体的机械化。在开禁等政策、自然灾害,以及战争等影响下,镇赉县土地开发呈由东部和中部的平坦地区向西部地势较高地区扩展的过程。     

资源环境信息系统集成平台的设计、实施与应用

“数字地球”概念的提出对地理信息系统的集成开发提出了新的要求。针对目前一些主流的地理信息系统数据库设计及系统集成技术,比较分析了不同解决方案的特点及存在的问题,并通过具体实例,展示不同方案的实际应用效果。为实用型的地理信息系统应用软件的设计和实施提供参考。     

一次强烈发展西南低涡的中尺度结构分析

2021年8月7—8日,四川盆地中东部出现大暴雨、局地特大暴雨,是重庆2021年度社会影响最大的一次暴雨过程。采用多源观测及ERA5再分析资料,对此次大暴雨过程进行诊断分析。结果表明：大暴雨发生在低槽移入四川盆地诱发暖性西南低涡背景下,具有显著的阶段性、跳跃性和极端性特征。大暴雨先后形成于西南低涡中心东南部、西南低涡东侧和西南低涡南侧暖湿的边界层辐合线附近。各阶段大暴雨均由移动缓慢、维持时间达3~6 h的β中尺度对流系统影响形成,暖湿不稳定和弱垂直风切变为β中尺度对流系统的形成提供了有利的环境条件。涡度分析表明,西南低涡的发展主要源于低空辐合及垂直涡度输送效应,但暴雨区的正涡度发展与西南低涡并不完全相同,水平涡度倾侧效应较为显著。第一阶段暴雨区正涡度主要源于对流层中低层西南低涡中心附近显著的低空辐合、涡度垂直输送及水平涡度倾侧效应;第二阶段和第三阶段暴雨区正涡度主要源于边界层辐合及边界层以上的水平涡度倾侧效应,边界层辐合触发暖湿大气中的中尺度对流活动促进了第二阶段和第三阶段大暴雨的形成。

     

More than Carbon Stocks： A Case Study of Ecosystem-based Benefits of REDD＋ in Indonesia

During the 15th Conference of the Parties(COP 15),Parties agreed that reducing emissions from deforestation and forest degradation and enhancing ’removals of greenhouse gas emission by forests’(REDD+) in developing countries through positive incentives under the United Nations Framework Convention on Climate Change(UNFCCC) was capable of dealing with global emissions.As REDD+ seeks to lower emissions by stopping deforestation and forest degradation with an international payment tier according to baseline scenarios,opportunities for ecosystem benefits such as slowing habitat fragmentation,conservation of forest biodiversity,soil conservation may be also part of this effort.The primary objective of this study is to evaluate ecosystem-based benefits of REDD+,and to identify the relationships with carbon stock changes.To achieve this goal,high resolution satellite images are combined with Normalized Difference Vegetation Index(NDVI) to identify historical deforestation in study area of Central Kalimantan,Indonesia.The carbon emissions for the period of 2000-2005 and 2005-2009 are 2.73 × 10 5 t CO 2 and 1.47 × 10 6 t CO 2 respectively,showing an increasing trend in recent years.Dring 2005-2009,number of patches(NP),patch density(PD),mean shape index distribution(SHAPE_MN) increased 30.8%,30.7% and 7.6%.Meanwhile,largest patch index(LPI),mean area(AREA_MN),area-weighted mean of shape index distribution(SHAPE_AM),neighbor distance(ENN_MN) and interspersion and juxtaposition index(IJI) decreased by 55.3%,29.7%,15.8%,53.4% and 21.5% respectively.The area regarding as positive correlation between carbon emissions and soil erosion was approximately 8.9 × 10 3 ha corresponding to 96.0% of the changing forest.These results support the view that there are strong synergies among carbon loss,forest fragmentation and soil erosion in tropical forests.Such mechanism of REDD+ is likely to present opportunities for multiple benefits that fall outside the scope of carbon stocks.     

Near-source noise suppression of AMT by compressive sensing and mathematical morphology filtering

In deep mineral exploration, the acquisition of audio magnetotelluric (AMT) data is severely affected by ambient noise near the observation sites; This near-field noise restricts investigation depths. Mathematical morphological filtering (MMF) proved effective in suppressing large-scale strong and variably shaped noise, typically low-frequency noise, but can not deal with pulse noise of AMT data. We combine compressive sensing and MMF. First, we use MMF to suppress the large-scale strong ambient noise; second, we use the improved orthogonal match pursuit (IOMP) algorithm to remove the residual pulse noise. To remove the noise and protect the useful AMT signal, a redundant dictionary that matches with spikes and is insensitive to the useful signal is designed. Synthetic and field data from the Luzong field suggest that the proposed method suppresses the near-source noise and preserves the signal well; thus, better results are obtained that improve the output of either MMF or IOMP.     

关联演化视角下地理学区域韧性分析的新思考

区域韧性是一个区域应对发展进程中短期冲击与长期变化、积极进行自我调适与转型的能力,表征了区域的适应性、创新性与可持续性,作为新兴理念反映了地理学可持续发展与区域研究的新需求。本研究综述了区域韧性研究进展,基于关联演化视角,探索构建区域韧性认知框架,将情境分析与过程分析并重,思考并总结区域韧性分析的方法论,尝试建立区域韧性评估方程,从经济、社会、环境及制度四个维度进行区域韧性评估,将区域韧性应用于中国地理学研究,分析中国区域韧性研究的一般性与特殊性,将区域韧性研究对接中国实际问题,以期对区域韧性研究做出理论贡献,助推地理学区域发展研究及相关认知领域的跨学科讨论、知识集成与学术交流,为国家制定相关区域政策提供参考,并为国家及区域可持续发展提供科学指引。     

Dynamic Prediction Model of Overburden Settlement in Deep Mining Areas based on Space–Time Relationship

Natural Resources Research - Depletion of shallow mineral resources caused by deep mining has become an inevitable trend, and deep mining can increase safety accidents and geological hazards....     

Isolation and pharmacological activities of bromophenols from Rhodomela confervoides

Four bromophenols were isolated from the extract of marine red alga,Rhodomela confervoides by column chromatography and HPLC methods. By means of spectroscopic methods inclding IR, MS, 1D, and 2D-NMR techniques, their structures were elucidated as (1) 3-bromo-4,5-dihydroxy benzoic acid methyl ester; (2) bis (2,3-dibromo-4,5-dihydroxybenzyl) ether; (3) 3,4-dibromo-5-(methoxymethyl)-1,2-benzenediol and (4) 3-bromo-4,5-dihydroxy-benzaldehyde. Compound 1 was first isolated from the algae in nature, and 1, 4 were found to have selective cytotoxic activities against KB, Bel 7402 and A549 cells, 2 showed powerful antibacterial activities againstStaphylococcus aurens andPseudomonas aeruginosa. Supported by National “863” Program (No. 2004AA625030, 2001AA620503), Quingdao marine sciences project (No. 04-2-NN-26) and Key Knowledge Innovative Project of the Chinese Academy of Sciences (KZCX3-SW-215).     

对地方电视台转播CCTV时延的测定

讲述了同步广播卫星电视时间信号的测量方法和测量结果，获得了CCTV1、CCTV2通过同一颗卫星（亚太－1A）转播的时延差值为16333μs，测量精度在10ns以内；CCTV2、CCTV4分别经两颗卫星（亚太－1A、亚洲－Ⅱ）转播，在陕西天文台卫星地面接收站时延差值为1644．20μs，精度为50μs，并分析了影响时延差值和精度的原因。同时测量了地方电视台转播亚太－1A的CCTV信号与直接接收亚太－1A的CCTV信号的时延差值，其测量精度为0．1μs。这些结果为利用同步广播卫星的电视信号进行高精度的时间服务提供了参考依据。