Arsenic distribution and source in groundwater of Yangtze River Delta economic region,China

This thesis focuses Arsenic(As) distribution and occurrence in groundwater of Yangtze River Delta economic region, East China. 2019 groundwater samples were collected to analyze 26 chemical compositions, including As. The Principal Component Analysis(PCA) was used to find out As source in groundwater. The results show that average As concentration in groundwater of this study is 9.33 μg/l, and maximum As concentration is up to 510 μg/l. The variation coefficient is 314.34%. High arsenic phreatic water(10 μg/l) distributes along the Yangtze River and its estuary. Weak hydrodynamic conditions, wide p H value variation range and deteriorating environment are dominating factors, especially in Yangtze River Delta. The PCA suggests that arsenic in phreatic water is mainly of natural origin. Part of arsenic may directly originate from sediment organics and be related to organics decomposition.     

The contingency of medicare physician spending on population densities and sizes

The exploration of the spatial association between Medicare physician spending and population densities and sizes could possibly facilitate the investigation of the causal mechanisms beneath the variation in medical care. We acquired the U.S. Medicare physician expenditures and regional demographic and geographic data in 2006 from the Dartmouth Atlas of Health Care. Six geographic units—states, counties, Hospital Referral Regions, Hospital Service Areas, Metropolitan Statistical Areas, and state non-Metropolitan Statistical Areas—were used as units of study. Pearson correlation analysis, multivariable regression, and partial correlation analysis were employed. Among six geographic units, Pearson correlation coefficients between Medicare physician expenditures and logarithmic population densities ranged from 0.42 to 0.63 (p < 0.05 for all), and between the expenditures and logarithmic population sizes from 0.31 to 0.65 (p < 0.05 for all). When population health, differential demand, market structure, and data reporting bias were controlled, population densities and sizes were positively associated with Medicare physician expenditures in most models. Population densities and sizes could explain considerable amounts of regional variation in Medicare physician spending. We concluded that Medicare physician spending was contingent on population densities and sizes. Because population densities and sizes are produced by more fundamental qualities such as natural environments and resources and thus are not easily manipulated, they are suggestive in health policy studies. Further research might investigate population distribution associated properties such as geographic distribution of health care resources, spatial dynamics of medical technology distribution, and cultural and psychological factors.     

河南焦作云台山早前寒武纪变质基底锆石SHRIMP U-Pb年龄

应用离子探针技术,对华北太行山南缘钾长石化长英质副片麻岩和钾长石化片麻状奥长花岗岩进行了锆石年龄测定。钾长石化长英质副片麻岩的变质原岩为泥砂质碎屑沉积岩,其形成时代很可能为新太古代。碎屑锆石普遍存在强烈铅丢失,靠近上交点的5个数据点207Pb/206Pb加权平均年龄为3399Ma±8Ma,代表了物源区组成的时代。钾长石化片麻状奥长花岗岩2组锆石207Pb/206Pb加权平均年龄分别为2511Ma±13Ma(岩体形成时代)和2735Ma±16Ma(残余锆石年龄),分别代表该岩体形成时代和残余锆石年龄。新的资料支持了华北克拉通中部造山带太古宙地质体与其东部陆块存在亲缘关系的认识。     

中国的板块构造区划

20世纪60年代板块构造学说传入中国,为广大地学工作者所接受并应用于相关的地质工作中。在新一代地质志的研究中,以板块学说为主导,已经成为共识。从板块构造来认识,板块的组成包括其核心及边缘。其核心为克拉通,由稳定的陆块组成;边缘包含了不同的活动大陆边缘和被动大陆边缘。边缘在后期板块汇聚的过程中,常由汇聚或碰撞等不同方式而成为不同的造山带。板块之间具有不同形式的汇聚带,其中主要是地壳对接消减带。在地球发展历史的过程中,不同时期的板块构造格局常有很大的变化。因此,本文以古生代的构造格架为主,探讨对中国大陆进行板块构造区划中的一些相关问题,并对全国的区划提出了一个初步方案。此方案将全国划分为7个I级单元(板块),30个II级单元(克拉通和造山带)以及103个III级单元。     

Detecting space–time patterns of disease risk under dynamic background population

Journal of Geographical Systems - We are able to collect vast quantities of spatiotemporal data due to recent technological advances. Exploratory space–time data analysis approaches can...     

中国大地构造区划及若干问题

在"新全球构造"思想的指导下,以板块构造学说为基础,以大陆动力学为线索,对中国区域地质构造和演化进行讨论并进行构造区划。由于板块构造随着时间的推移不断地发生变化,本文的构造区划以古生代时中国的板块构造格局为基础,同时考虑前古生代和后古生代时期中国的地壳构造演化,将中国划分为7个一级构造单元(板块)和30个二级构造单元,包括克拉通(或微陆块)和不同时期的造山带。在此基础上讨论了它们的边界和相互关系。     

地壳再循环与大陆碱性玄武岩的成因：以山东新生代碱性玄武岩为例

      大陆碱性玄武岩在地球化学特征上与洋岛玄武岩高度相似,被看做是板内玄武岩在大陆上的典型代表。本文以山东 新生代碱性玄武岩为例,探讨大陆碱性玄武岩的成因。山东新生代碱性玄武岩按时空分布特征可以分为两类：早期定向分 布、相互平行的三个火山群（包括鲁西的潍坊火山群、沂水火山群和胶东的蓬莱火山群）和晚期杂乱分布的孤立小火山。 早期火山群碱性较弱,以碱性橄榄玄武岩和碧玄岩为主,微量元素特征和同位素组成变化大;晚期孤立小火山碱性强,以 碧玄岩和霞石岩为主,微量元素特征和同位素组成较均一。因此,从岩性组成和时空分布特征看,山东的火山群相当于洋 岛/海山的造盾期玄武岩,而孤立小火山接近于洋岛/海山上的复苏期玄武岩。潍坊火山群和沂水火山群在Sr-Nd,Nd-Hf同位 素相关图上都存在从亏损到富集的两端元混合排列趋势,但两者的排列趋势有一点区别。其中同位素富集的端元相对于原 始地幔具有偏低的Ce/Pb比和偏高的Ba/Th比,指示其为大陆下地壳物质。同时,这种富集端元的Th/La比值明显低于大陆下 地壳的平均值,其放射成因Hf相对于放射成因Nd过剩（即Nd-Hf同位素解耦）,说明这种富集端元不是岩浆上升过程中混染 的下地壳物质,而是经历过早期熔融的再循环大陆下地壳（榴辉岩或者石榴辉石岩）。鲁西两个平行火山群在同位素排列上 的区别类似于夏威夷玄武岩中的KEA链和LOA链,因此,山东的平行火山群的深部动力学背景可能是地幔柱,再循环大陆 下地壳物质可能是这种地幔柱的重要组成物质。晚期的孤立小火山在地球化学特征上与火成碳酸岩非常相似,如在原始地 幔标准化图上都具有K,Pb,Zr,Hf,Ti的负异常等特征,因此我们认为其地幔源区为碳酸盐化的橄榄岩。孤立小火山中等亏损 的Sr,Nd,Hf同位素特征支持碳酸岩熔体来自年轻的（中生代？）再循环洋壳。     

大直径深层钻孔灌注桩拔除工艺研究

结合郑州南站连接线明挖隧道（拔桩区间）拟拔桩基直径大、桩长的特点,对桩体受力特征和拔桩工艺进行了研究。通过拔桩过程中桩周土破坏模式和桩体自身的抗拉强度分析计算,选取有效的减阻方法并应用于工程实践,取得良好效果。最后总结出大直径深层钻孔灌注桩拔除工程中桩身局部扩大、桩侧摩阻力过大和断桩等问题及相应的解决方法,供今后类似工程借鉴。     

准噶尔芦草沟组与黄山街组的古气候条件

准噶尔中二叠统芦草沟组无论是从岩性还是所含古生物，均表明形成于持续炎热的气候条件之下，当时由于准噶尔古板块与塔里木古板块的拼合造山，造成准噶尔周缘火山强烈喷发和自欧洲东移的干旱炎热气流对准噶尔均有明显的影响。上三叠统黄山街组形成时干旱气候缓解，降水量增加，该组沉积物反映出温暖的亚热带气候特征。因此，从成油的古气候条件来说，芦草沟组要优于黄山街组。     

东准噶尔蒙西斑岩铜钼矿床脉体特征及其形成机制

蒙西斑岩铜钼矿床位于东准噶尔伊吾县琼河坝花岗岩北侧,以发育细脉、网脉状矿化为特征。脉体类型多样,包括石英脉、石英硫化物脉和硫化物脉等。根据脉体力学成因机制,其又可划分为水压破裂充填脉和构造破裂充填脉。构造破裂充填脉体按破裂形成的位错特征有正断与逆断两种。地表石英脉产状陡立,明显受断裂控制。脉体体积分数统计结果显示流体富集区呈向北缓倾的带状分布于深100～400m范围内,并与矿化富集带有较好的对应关系。脉体富集带内,脉体以共轭形式存在,一组为倾角较小的逆断破裂充填脉,另一组为倾角较大的正断破裂充填脉,他们可能为缓倾逆冲剪切带的次级破裂与充填脉,即富矿带内脉体是沿矿区低角度逆冲断裂次级破裂面充填的。矿区地表及深部(400m以下)脉体以陡立为主,矿化较弱。矿区流体的运移具先沿水压直立破裂往上运移,进入剪切带后沿剪切带次级破裂侧向和向上运移,并在剪切带中富集成矿。低温矿物组合脉体穿切高温矿物组合脉体的特征说明脉体形成过程矿区处于隆升构造环境,这对斑岩铜矿成矿有利。