华南震旦系陡山沱组磷质震积岩及其与多细胞生物群相关性初探

埃迪卡拉纪（震旦纪）陡山沱期是Rodinia超大陆裂离的重要地质时期,是多细胞生物起源和发展的重要转折时期和磷质聚集时期,也是化学、气候和环境变化的剧烈时期。液化岩脉、液化角砾岩、脉化变形构造、以及阶梯状层内断层等磷质震积岩的发现,表明扬子地区在陡山沱期晚期至少发生过两次以上的地震事件。地震构造运动将地球内部积累能量快速地释放,可能是磷质来源和热水活动一种重要的方式或通道。海水中磷等无机营养盐分的增加,海水温度的升高,有利于多细胞生物的起源和发展,同时多细胞生物的繁盛又有利于磷的聚集。     

长基线时间序列季节项提取和重构方法分析

运用经验模态分解（EMD）、集合经验模态分解（EEMD）和完备总体经验模态分解（CEEMD）3种方法对原始基线时间序列进行分解,得到各自时间序列的本征函数模态分量（IMF）、相关系数及周期性强度,进而确定其季节项分量,同时通过比较季节项和原始基线时间序列的叠加功率谱图优选分解方法。结果表明,CEEMD方法对基线时间序列季节项提取和重构效果最佳。     

Study on Coastal Protection Engineering in the Area of Abandoned Yellow River Mouth

This paper reviews the history of coast evolution and coastal protection in the area of theabandoned Yellow River mouth in Jiangsu Province,analyzes the erosion characteristics and dynamic en-vironment,evaluates the efficiency of coastal protection engineering works and designs the dimensions ofthe main seadike and offshore submerged dam.A gerneral scheme of shore protection for this area is pro-posed.     

Colonisation of epilithic diatom population of the River Taff, South Wales, U.K.

1. A light and scanning electron microscopic study of the structure of epilithic diatom communities was carried out at two sites on the River Taff, South Wales, an upstream unpolluted site (Site 1) and a downstream polluted site (Site 2). 2. Community structure at the micro-scale revealed that, although communities at both sites were similar in terms of species present (similarity indices ranging between 0.44 and 0.96), they were very different with respect to their physical structure. 3. The traditional approach in studying epilithic diatom communities ignores information relating to community structure. The combination of light and scanning electron microscopy proved to be most useful for studying the epilithic diatom communities. 4. The examination of community succession on stone substrata showed that communities were highly dynamic on a weekly time scale, which suggests that the “age” of a substratum is a very important determinant of the attaching communities. A change from a prostate, two-dimensional community structure to an erect, three-dimensional community structure, and a shift from the dominance of epilithic diatoms to the dominance of epiphytic diatoms were noted. Such a change was more noticed at the polluted downstream site, possibly due to a higher rate of surface pre-conditioning and biofilm production at this site than at the unpolluted upstream site.     

逸度模型在湖泊流域农药多介质归趋研究中的应用与展望

农药的施用在促进农业经济发展的同时,也带来了诸多环境问题.农药由农业活动排放进入到环境后会通过不同的途径在各介质之间进行迁移和转化,最后由径流作用汇聚于湖泊中,破坏生态环境,影响人类健康.因此,研究湖泊流域生态系统中农药的多介质归趋具有重要意义.使用基于逸度的多介质模型模拟农药在环境中的行为是一个十分有效的方法.逸度模型利用"逸度"的概念描述污染物在各个环境介质之间的迁移和转化过程趋势,其结果建立在化学物质自身物化性质和环境系统性质之上,不仅适用于预测农药在环境各介质中的残留水平,还可以揭示区域内污染的空间分布特征,是湖泊流域生态系统管理中一个重要的工具.本文综述了逸度模型的理论基础,对近年来国内外逸度模型的发展现状、相关环境模型及其在农药归趋研究和湖泊流域生态系统管理中的运用进行了总结,并展望了逸度模型在农药多介质研究中的应用前景,以期对我国农药的管理、合理施用方面提供科学与技术支持.     

湖泊蒸发观测与计算方法研究进展

湖泊蒸发是连接湖泊水分循环与能量平衡的关键纽带之一,认识湖泊蒸发过程对于理解湖-气间相互作用机制十分重要。然而,由于湖泊的形态结构、地理位置和气候背景不同,各湖泊在不同时间尺度上的蒸发特征不同。湖泊蒸发存在复杂的物理驱动过程、时间尺度相关的反馈以及空间异质性。准确地捕捉并量化湖泊蒸发过程,仍是湖沼学、水文学和气象学等学科的重要研究内容。本文首先介绍了湖泊蒸发的主要观测手段,然后概述了湖泊蒸发在日内、季节、年际、年代际四种不同时间尺度的变化特征;梳理了不同时间尺度各要素对湖泊蒸发的影响,以及湖泊蒸发与湖泊面积和深度等形态结构特性及纬度和海拔等地理因素之间的关系;对自涡度相关技术等高精度仪器应用以来的湖泊蒸发研究进展做出了总结。     

Variation in the vertical zonality of erodibility and critical shear stress of rill erosion in China's Hengduan Mountains

Soil erodibility is an essential parameter used in soil erosion prediction. This study selected the Liangshan town watershed to quantify variation in the vertical zonality of rill erodibility (k_r) in China's ecologically fragile Hengduan Mountains. Soil types comprised of yellow–brown (soil A), purple (soil B), and dry-red (soil C) in a descending order of occurrence from the summit to the valley, which roughly corresponds to the vertical climate zone (i.e. cool-high mountain, warm-low mountain, and dry-hot valley sections) of the study area. With elevation, vertical soil zonality varied in both soil organic matter (SOM) content and soil particle-size fractions. A series of rill erosion-based scour experiments were conducted, using water discharge rates of 100, 200, 300, 400, 500, and 600 mL min^-1. Additionally, detachment rates (Dr) were measured under three hydrological conditions (the drainage, saturation, and seepage treatments). Results show that both Dr and flow shear stress (Ʈ) values increased as discharge increased. As elevation increased, the k_r values decreased, while the vertical zonality of critical shear stress (Ʈ_c) values showed no obvious variation. The highest k_r values were observed during the seepage treatment, followed by the saturation treatment then drainage treatment, indicating that variation in vertical hydraulic gradients could significantly alter k_r values. This study also found that land-use types could also alter k_r and Ʈ_c values. Further research, however, is necessary to better quantify the effects of subsurface hydrological conditions and land-use types on k_r under different soil zonalities in China's Hengduan Mountains. © 2018 John Wiley & Sons, Ltd.     

强震作用下抗震陷黄土改良地基的微观特征分析

基于动三轴试验和SEM细观结构测试试验,结合图像分析处理软件,对强震荷载前后宝兰客运专线沿线典型震陷性黄土及其经物理、化学和复合改良方法处理后的试样进行微观尺度的结构变形演化规律研究,探讨不同改良方法对土体微结构的影响及其与震陷系数之间的内在联系。结果表明:(1)物理改良方法对于消除大孔隙和架空孔隙结构的效果最为明显,同时对颗粒级配和结构也有调整;(2)化学改性方法则从颗粒接触方式、粒间胶结程度等方面影响土体强度,且不同化学反应的参与可生成独特的玻璃微珠或絮凝状细结构,从而大大提升土体某项参数指标,进而在强震中分别起到填充、胶结或缓冲作用;(3)强震作用前后不同改良方法对各微观要素的改变与相应的残余应变现象吻合较好,说明微结构能有效反映改良黄土残余变形的强弱。     

适用于县级大比例尺测绘的平面直角坐标系整合方法与实践

县(市)开展大比例尺测图时,应首先收集已有的测绘成果及采用的平面直角坐标系统。当测区处于国家统一3°投影带边缘或测区高程较大时,为满足每千米长度变形值不大于2.5 cm,必须建立相应的地方平面直角坐标系。本文针对某县已经建立的基于多种平面直角坐标系的测绘成果,介绍了一种将现有测绘成果转换到地方平面直角坐标系的方法。     

火星快车HRSC线阵影像投影轨迹法近似核线重采样

火星快车高分辫率立体相机(high resolution stereo camera, HRSC)线阵推扫式影像具有分辫率高、全球覆盖性好等特点,对火星快车HRSL影像进行摄影测量处理可获取火星全球高分辫率地形数据,而影像匹配是自动获取地形数据的关键利用核线几何约束可以将影像匹配搜索范围由二维降至一维本文在构建火星快车HRSC线阵影像严格几何模型的基础上,提出了一种近似核线重采样方法首先,利用投影轨迹法分析 HRSC线阵影像核线的直线性与平行性;然后,将原始HRSC影像进行微分纠正生成水平影像,分析投影轨迹法得出的核线在水平影像上的几何关系并确定近似核线方向,再沿核线方向进行核线重排生成近似核线影像实验结果表明,本文算法生成的近似核线影像同名点上下视差优于1个像素,且在水平影像上进行近似核线重采样减少了由外方位元素变化引起的几何畸变,更有利于影像匹配。