Plant distribution at the mobile dune scale and its relevance to soil properties and topographic features

A survey was conducted in an 11-year recovery mobile dune (RMD11) and a 20-year recovery mobile dune (RMD20), in Horqin Sandy Land, Northern China, to determine plant distribution at the mobile dune scale and its relevance to soil properties and topographic features. The results showed that (1) vegetation cover and species number increased from dune top to bottom in the restoration process of mobile dune; (2) the average value of soil organic C, total N, pH, relative height of sampling site, very fine sand content and soil water contents (40−60 and 60−80 cm) of RMD11 were less than that of RMD20, respectively, and there were significant differences (P < 0.05) between the two dunes; (3) soil resources were redistributed by shrub restoration and relative height of sampling site on dune. The distribution of sand pioneer plant, Agriophyllum squarrosum, was positively related to the relative height of sampling site and soil water content, while that of other herbaceous plants was positively related to soil nutrients in the restoration process of mobile dune. These results suggest that at mobile dune scale, plant distributions are determined by a combination of soil properties and topographic feature. Much effort should be made to preserve the interdune lowland and to improve the level of soil nutrients on mobile dune.     

热带对流层低频振荡过程的能量学初步分析

本文利用线性化的能量方程和交叉谱方法分别研究了准两周振荡和准40天振荡的能量来源及其转换过程。发现:在热带对流层中,对于低频振荡过程来说,来自中高纬度的侧向强迫作用和水汽凝结的加热作用是非常重要的,为扰动的产生和维持提供了重要能源。而正、斜压不稳定作用对扰动发展的作用是极小的。并且指出,在东亚热带对流层上部,准两周振荡通过与平均气流的相互作用为基本气流提供许多能量,对于维持这里的高空东风急流有重要作用。准40天振荡向平流层输送能量,对平流层平均环流的演变可能有重要贡献。      

连作马铃薯根系分泌物鉴定及其对尖孢镰孢菌(Fusarium oxysporum)的作用

为了揭示马铃薯连作化感物质与枯萎病之间的关系,通过水培和田间长期定位试验相结合方法,收集不同连作年限马铃薯根系分泌物,采用GC-TOF-MS进行分离鉴定.结果表明:在检测到的马铃薯根系分泌的48种物质中有机酸占30种.比较轮作、连作5年和连作10年马铃薯根系分泌物中有机酸的相对含量,发现苹果酸和棕榈酸的差异比较大.马铃...     

Snow water equivalent over Eurasia in the next 50 years projected by aggregated CMIP3 models

Based on remote sensing snow water equivalent (SWE) data, the simulated SWE in 20C3M experiments from 14 models attending the third phase of the Coupled Models for Inter-comparison Project (CMIP3) was first evaluated by computing the different percentage, spatial correlation coefficient, and standard deviation of biases during 1979–2000. Then, the diagnosed ten models that performed better simulation in Eurasian SWE were aggregated by arithmetic mean to project the changes of Eurasian SWE in 2002–2060. Results show that SWE will decrease significantly for Eurasia as a whole in the next 50 years. Spatially, significant decreasing trends dominate Eurasia except for significant increase in the northeastern part. Seasonally, decreasing proportion will be greatest in summer indicating that snow cover in warmer seasons is more sensitive to climate warming. However, absolute decreasing trends are not the greatest in winter, but in spring. This is caused by the greater magnitude of negative trends, but smaller positive trends in spring than in winter. The changing characteristics of increasing in eastern Eurasia and decreasing in western Eurasia and over the Qinghai-Tibetan Plateau favor the viewpoint that there will be more rainfall in North China and less in the middle and lower reaches of the Yangtze River in summer. Additionally, the decreasing rate and extent with significant decreasing trends under SRES A2 are greater than those under SRES B1, indicating that the emission of greenhouse gases (GHG) will speed up the decreasing rate of snow cover both temporally and spatially. It is crucial to control the discharge of GHG emissions for mitigating the disappearance of snow cover over Eurasia.     

南海南部大陆架的残留沉积

研究了南海南部大陆架的残留沉积物的粒度、石英砂表面结构特征、生物分布等，并指出残留沉积普遍遭受改造。按其早期的形成环境差异和改造作用不同，划分出加里曼丹－巴拉望残留沉积区和亚南巴斯－纳土纳残留沉积区。     

高中地理新教科书中的灾害教育及教学路径

当今时代全球自然灾害频发,高中地理学科承担着对学生进行灾害教育的使命。人教版(2019版)高中必修《地理一》在叙述性文本、图像、案例以及活动栏目中分别阐述了灾害教育内容,构建了良好的灾害教育体系,有利于培养学生掌握灾害知识、厚植积极向上的灾害情感、获取应对灾害的实践能力与素养。本文提出高中地理灾害教育的教学路径:立足区域情境,习得完善的灾害知识;挖掘灾害文化的育人价值,引导学生树立正确的情感、态度、价值观;培养学生应对灾害的实践能力与素养,落实“立德树人”根本目标。     

地震波阻抗约束下的储层地质建模方法与实践

以地质统计学为基础的三维地质建模技术已成为当今储层精细描述中的一项关键技术,但该项技术存在着一个最大的限制就是对硬数据的密度要求十分苛刻,因而多用于井网密度大的已开发区的储层精细描述。而在勘探区块,多采用地震属性资料作为软约束,来弥补资料不足的缺陷。本文以我国海上某油田为例,探讨了应用地震反演资料约束三维储层建模的几种方法,并提出＂多条件、多级约束＂的建模策略。研究表明,有效地应用包括地震信息在内的多学科信息进行岩相随机建模,能有效地弥补井间信息不足的缺陷,降低地质模型的不确定性,所建立的模型能很好地综合井资料的纵向高精度和地震资料的横向高精度信息,可以成功地应用三维随机建模技术解决勘探开发阶段的储层精细描述问题。     

歧口凹陷火成岩的地球化学特征、形成时代及构造意义

歧口凹陷侏罗系火成岩主要以中-酸性的流纹岩、粗面岩和粗面安山岩为主,白垩系主要为中-基性的粗面玄武岩和玄武质粗面安山岩,第三系火成岩以粗面玄武岩、碱性玄武岩及辉绿岩为主。同位素定年结果获得白垩系玄武岩的年龄为133±20 Ma,安山岩和粗安岩年龄分别为111.8±0.9 Ma和122.1±3.1 Ma,第三系辉绿岩年龄为16.57±0.23 Ma。地球化学特征显示,侏罗系火成岩相对低钛、高碱和钠、低铁镁,轻重稀土元素强烈分馏、微量元素相对富集LILE、贫化HFSE、亏损Nb和Ti、P,部分高Sr、低Yb,总体指示为挤压环境下加厚地壳物质的熔融产物,白垩系火成岩中等钛和碱的含量,高钠、铁和镁,稀土和微量元素显示其来自于伸展背景的富集地幔源,但受到陆壳物质的混染,第三系火成岩高钛含量、中等碱含量但变化大、高钠、富铁镁,轻重稀土元素分馏弱到中等、微量元素富集LILE和HFSE,同样来自板内伸展环境的富集地幔源的产物。表明歧口凹陷构造转换发生在晚侏罗世和早白垩世之间。     

安徽拂晓地区地物化特征及找矿意义

拂晓地区位于苏鲁超高压变质带安徽段的张八岭地区,地质构造条件与山东段的胶东金矿矿集区类似,具有较好的成矿地质条件和找矿前景。为探索拂晓地区金矿找矿前景,我们系统的开展地物化工作,以面积性的磁法、化探异常为依据,圈定隐伏岩体范围,提供多目标的直接找矿信息,减小找矿范围,预测出两个重点找矿远景区。在重点找矿远景区内,部署了两条可控源音频大地电磁和频谱激电剖面对重点区域的深部纵向结构特征进行探索。综合研究拂晓地区的地物化资料,提出以“弱磁异常-化探异常中心-中等强度的电性异常”为特征的物化探找矿标志;“煌斑岩脉-闪长质脉岩”为特征的地质直接找矿标志;“次级断裂带-不同岩体间的接触带区域”为重点找矿区域的地物化综合找矿方法,有效的增强了找矿能力。为安徽拂晓地区及其邻区的矿产勘查工作提供一定的指示。     

汤原断陷断裂构造特征及其对油气成藏的控制作用

汤原断陷是典型的受断裂控制的陆相盆地。盆地内断裂极为发育。断裂的发育主要有 Ｎ Ｅ向和 Ｎ Ｗ － Ｎ Ｗ Ｗ 方向,断裂的分布具有东西分带,南北分群的特征。按断裂的成因类型可划分出７ 种类型。断裂对油气生成、运聚及成藏的控制作用主要表现在：基底大断裂控制了烃源岩的展布,主干断裂控制了圈闭的形成和分布,断裂为油气运移提供了通道作用,断裂的封闭性为油气的聚集成藏提供了遮挡条件。