Dome A冰川学研究进展及深冰芯计划展望

目前,位于东南极冰盖分冰岭中心的冰穹-Dome A已成为深入理解南极冰盖演化、稳定性和找寻地球气候久远记录的研究热点。通过整理总结在Dome A获得的冰川学研究进展,结合国际冰芯科学研究计划(International Partnerships in Ice Core Sciences,简称IPICS)有关寻找最古老冰芯的相关资料,对Dome A的气象要素、地貌、冰厚、冰下地形、冰体流速、冰盖内部结构等环境特征进行归纳分析,讨论Dome A冰川学的最新发展及其对深冰芯钻探计划的影响,并分析概述Dome A深冰芯钻探需考虑的问题和未来发展动向。     

Modeling the adsorption of Cd (II), Cu (II), Ni (II), Pb (II) and Zn (II) onto montmorillonite

The adsorption of five toxic metallic cations, Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II), onto montmorillonite was investigated as a function of pH and ionic strength and a two-site surface complexation model was used to predict the adsorption data. The results showed that in the lower pH range, 3∼6 for Cd, Cu, Ni and Zn, and 3∼4.5 for Pb, the adsorption was greatly affected by ionic strength, while in the higher pH range, the adsorption was not. In the lower pH range, the metallic cations were mainly bound through the formation of outer-sphere surface on the permanently charged basal surface sites (≡X⁻), while in the higher pH range the adsorption occurred mainly on the variably charged edge sites (≡SOH) through the formation of inner-sphere surface complexes. Acid-base surface constants and metal binding constants for the two sites were optimized using FITEQL. The adsorption affinity of the five metallic cations to the permanently charged sites of montmorillonite was Pb > Cu > Ni ≈ Zn ≈ Cd, while that to the variable charged sites was Pb ? Cu > Zn > Cd > Ni.     

华北地区一次强灰霾污染的天气学效应

利用在线耦合的大气化学模式WRF-Chem V3.6(Weather Research Forecasting Model with Chemistry Version 3.6)及环境、气象观测数据,在完成大气化学方案优选的基础上,研究了华北地区一次重霾污染过程(2013年2月15~17日)对气象条件的反馈作用。重点关注一次颗粒物、无机气态成分和挥发性有机污染物的人为排放对PM2.5(空气动力学当量直径小于等于2.5μm的颗粒物,即细颗粒物)生成的贡献,探讨了由此引发的气象条件的变化。模拟结果显示,上述3种人为源的综合排放对华北地区PM2.5浓度的平均贡献率为91.27%,其中对北京、秦皇岛和沧州的贡献率分别达96.9%、95.9%和97.2%。这使区域地面太阳向下短波辐射降低近15.99%,区域平均地面辐射强迫达-26.51 W m-2,由此导致地面温度下降0.14°C(3.68%),逆温增强,垂直温度梯度(?T/?z)升高0.026 K km-1,边界层高度降低18.92 m(8.77%),平均风速减少约0.014 m s-1(0.35%),相对湿度绝对值升高0.51%,地面平均气压降低0.86 Pa。对于15~17日污染过程,人为源综合排放的气溶胶对短波辐射的影响在天气过程中占主导地位,对边界层高度的影响较大,但不起主导作用,对温度、风速、相对湿度、气压的作用则远小于天气系统本身。挥发性有机污染物(Volatile Organic Compounds,VOCs)作为二次有机气溶胶(Secondary Organic Aerosol,SOA)的前体物,其人为排放对SOA浓度的贡献率约为99.6%。同时,VOCs通过调整大气反应活性促进无机气态成分向无机盐转化,它对硫酸盐和硝酸盐浓度的贡献达50%以上。然而,VOCs对整个PM2.5浓度的贡献不及各种源综合贡献的1/4。人为排放的VOCs对气象场的反馈与综合排放的作用基本一致,但对地面气压的影响VOCs排放时以热力因子为主,而人为源综合排放时以动力因子为主。上述结果暗示,灰霾污染过程所引发的气象条件向不利于污染物扩散方向改变,这可能促进污染物的局地累积、增强污染程度并延长区域内重污染的持续时间。因此,在探讨区域性灰霾污染成因时,灰霾自身通过辐射强迫作用对大气的调节是不可忽视的重要影响因素。     

塔中地良奥陶系地层格架与沉积演化

塔里木中部地区奥陶系大致以Ⅰ号断裂为界分东北和西南两个地层分区,自下而上分白云岩段、灰岩段、泥质灰岩段、泥岩夹灰岩段、泥岩夹砂岩段、砂砾岩段、泥岩夹砂岩段、泥岩灰岩互层段和砂岩段等9个岩性段。早奥陶世,塔中地区以碳酸盐岩台地相为主,自西向东为局限台地相、开阔台地相、台地边缘相和深水斜坡相。中——晚奥陶世,塔中地区西部以混积陆架相为主,东部以深水斜坡相为主。中—晚奥陶世,塔中东部及塔东地区在构造上具弧后前陆盆地性质。中—上奥陶统地层完整地记录了该盆地从形成发展到消亡的过程,即早期为深水斜坡相复理石活动沉积,晚期演化为浅海陆架相稳定沉积。     

八卦庙金矿床中含金石英脉的地球化学特征及意义

八卦庙金矿床是分布于秦岭造山带中的一种中高温碳酸盐型热液金矿床。石英是其主要的脉石矿物之一，与金矿化密切相关。根据含金石英脉的产状可将其分为三种类型：①顺层石英脉；②含铁白云石石英脉；③ＮＥ向节理石英脉。它们在微量元素和稀土元素的组成特征上有一定的差异，分别形成于金的不同成矿阶段，是金在成矿作用过程中演化的产物。同时，为八卦庙金矿的成矿提供了条件。石英中包裹体测温结果为八卦庙金矿床的中温成因提供了证据     

软地层中斜拉群锚特性的研究

为了研究上海地区土层锚杆的群锚效应，本文以明德林（Ｍｉｎｄｌｉｎ）解为基础，通过引用根据试验所得的锚杆非线性传递函数，对软地层中斜拉锚杆的长度、间距、入土深度、压浆等因素对群锚效应的影响进行了探讨，得出一些有价值的结果。     

Seasonal Variations of the East Asian Subtropical Westerly Jet and the Thermal Mechanism

The seasonal variations of the intensity and location of the East Asian subtropical westerly jet (EAWJ) and the thermal mechanism are analyzed by using NCEP/NCAR monthly reanalysis data from 1961 to 2000. It is found that the seasonal variation of the EAWJ center not only has significant meridional migration, but also shows the rapid zonal displacements during June-July. Moreover, there exists zonal inconsistency in the northward shift process of the EAWJ axis. Analysis on the thermal mechanism of the EAWJ seasonal variations indicates that the annual cycle of the EAWJ seasonal variation matches very well with the structure of the meridional difference of air temperature, suggesting that the EAWJ seasonal variation is closely related to the inhomogeneous heating due to the solar radiation and the land-sea thermal contrast. Through investigating the relation between the EAWJ and the heat transport, it is revealed that the EAWJ weakens and shifts northward during the warming period from wintertime to summertime, whereas the EAWJ intensifies and shifts southward during the cooling period from summertime to wintertime. The meridional difference of the horizontal heat advection transport is the main factor determining the meridional temperature difference. The meridional shift of the EAWJ follows the location of the maximum meridional gradient of the horizontal heat advection transport. During the period from April to October, the diabatic heating plays the leading role in the zonal displacement of the EAWJ center. The diabatic heating of the Tibetan Plateau to the mid-upper troposphere leads to the rapid zonal displacement of the EAWJ center during June-July.     

Study on the Overfitting of the Artificial Neural Network Forecasting Model

Because of overfitting and the improvement of generalization capability (GC) available in the construction of forecasting models using artificial neural network (ANN), a new method is proposed for model establishment by means of making a low-dimension ANN learning matrix through principal component analysis (PCA). The results show that the PCA is able to construct an ANN model without the need of finding an optimal structure with the appropriate number of hidden-layer nodes, thus avoids overfitting by condensing forecasting information, reducing dimension and removing noise, and GC is greatly raised compared to the traditional ANN and stepwise regression techniques for model establishment.     

The Gas Resources Assessment Expert System of the Songliao Basin

The gas resources assessment expert system is one of the advanced methods for appraising oil and gas resources. The establishment of a knowledge base is the focal task in developing the expert system. This paper presents a summary of the mechanism and the major controlling factors in the formation of gas pools in the southeast uplift of the Songliao basin. Then an appropriate assessment model is established for trapping the gas resources and a knowledge base built in the expert system to realize the model. By using the expert system to appraise the gas-bearing probability of 25 major traps of the Quantou and Denglouku Formations in the Shiwu-Dehui area, the authors have proved that the expert system is suitable for appraising traps in the Songliao basin and similar basins.     

成都平原传统场镇与林盘居民点的分布特征及其影响因素——以成都郫县为例

基于近现代地图与相关地理信息，结合历史文献与实地考察，通过GIS空间分析、核密度估算、欧氏距离、基尼系数等方法，以传统林盘聚落的核心区成都郫县为例，定量揭示了1947、1970、1985、2000与2018年郫县林盘居民点的空间分布特征与场镇分布关系的变化情况。结果表明：1）不同时期林盘居民点的分布具有明显的空间差异性，在改革开放前，林盘居民点的分布极易受到政治经济中心的影响，在改革开放后，其具有均质化快速发展的特点，但城镇化的快速推进从根本上改变了林盘居民点的散居特征，其聚集程度明显增高。林盘居民点高密度区始终具有围绕传统场镇及城镇建成区分布的特点。2）传统场镇的市场半径大致为3 km，交通条件是其选址的首要因素，民国时期场镇选址主要受水路交通影响，建国后水路交通为场镇带来的交通便利逐渐被陆路交通所取代。3）传统场镇的分布会随着林盘居民的自组织行为与相关政策的调控而不断趋于均衡状态，但在改革开放之后，场镇由乡村市场驱动的自由放任式发展转变为地方政府驱动下的固定场所。4）林盘居民点具有沿河流水系分布的特点；传统时期林盘居民点与主要道路之间的关联性较低，但当前其具有沿道路分布的特点。