Distribution and enrichment of heavy metals in a sediment core from the Pearl River Estuary

A sediment core collected from coastal zone near the Qiao Island in the Pearl River Estuary was analyzed for total metal concentrations, chemical partitioning, and physico-chemical properties. Three vertical distribution patterns of the heavy metals in the sediment core were identified, respectively. The dominant binding phases for Cu, Pb, Cr, and Zn were the residual and Fe/Mn oxides fractions. Cd in all sediments was mainly associated with exchangeable fraction. Influences of total organic carbon content and cation exchange capacity on the total concentrations and fractions of almost all the metals were not evident, whereas sand content might play an important role in the distributions of residual phases of Cr, Cu, Pb, and Zn. In addition, sediment pH had also an important influence on the Fe/Mn oxides, organic/sulfide and residual fractions of Cr, Cu, and Zn. Contamination assessment on the heavy metals in the sediment core adopting Index of Geoaccumulation showed that Cr, V, Be, Se, Sn, and Tl were unpolluted, while Cu, Ni, Pb, Zn, Cd, and Co were polluted in different degrees throughout the core. It was remarkable that the various pollution levels of the metals from moderate (for Cu, Pb, and Zn) to strong (for Cd) were observed in the top 45 cm of the profiles. The relative decrease of the residual fraction in the upper 45 cm of the core is striking, especially for Zn and Cu, and, also for Pb, and Cr. The change in fraction distribution in the upper 45 cm, which is very much contrasting to the one at larger depths, confirms that the residual fraction is related to the natural origin of these metals, whereas in the upper part, the non-residual fractions (mainly the Fe/Mn oxides fraction) are increased due to pollution in the last decade. The possible sources for Cu, Pb, Zn, and Cd contaminations were attributed to the increasing municipal and industrial wastewater discharges, agricultural runoff, atmospheric inputs, and runoff from upstream mining or smelting activities, which may be associated with an accelerating growth of economy in the Pearl River Delta region in the past decade.     

多源遥感专题信息比较研究:现状、问题与展望

由于传感器特性、信息提取方法、模拟模型等不同,从多源、多时相的遥感数据获取各种遥感专题信息之间不可避免存在差异,在数据应用之前常常需要对这些专题信息进行比较和评价.多源遥感专题信息比较方法多种多样,依据处理单元或处理对象特性将多源遥感专题信息比较方法分为三大类:基于像元误差矩阵的比较、基于格局特征的比较和其他比较方法....     

Correction Method of Light Hydrocarbons Losing and Heavy Hydrocarbon Handling for Residual Hydrocarbon (S1) from Shale

Abstract: In China, hot researches on shale oil were raised by the important breakthrough of shale oil in America. Obviously, the first important issue is the actual shale oil resource potential of China, and the selection of the key appraisement parameter is vital to the shale oil resource amount. Among the appraisement parameters, the oil content parameter (S1) is the key one, but the evaluation result is generally lower because of light hydrocarbon losing and heavy hydrocarbon handling. And the more important thing is that the light hydrocarbon with small molecular weight is more recoverable, and therefore its amount is important to the total shale oil yields. Based on pyrolysis experiments and the kinetic model of hydrocarbon generation, correction factors and a model of light hydrocarbon losing and heavy hydrocarbon handling were established. The results show that the correction factor of heavy hydrocarbon handling is 3.2, and that of light hydrocarbon losing is controlled by kerogen type, maturity and hydrocarbon generation environment (closed or open).     

PALAEOZOIC TECTONIC PALAEOGEOGRAPHY OF THE CATHAYSIA IN EASTERN ZHEJIANG AND NORTHERN FUJIAN, CHINA

Based on the data about sedimentary facies and palaeogeography, this paper proves the existence of the Cathaysia (the part in eastern Zhejiang and northern Fujian, the same hereinafter) and makes a survey about its palaeogeography since Sinian Period. It also discusses the evolution of the tectonic environment of this region during Phanerozoic Eon, according to the features such as the composition of sandstones derived from the old land and alkalinity of volcanic rocks and so on. Continuous uplifting was maintained in Cathaysia during Sinian Period and Paleozoic Era, typically with no significant tectono-magmatic activity being observed. Its northwestern margin belongs to the type of passive continental margin during the middle and late phase of Caledonian Cycle. It showed the characteristics of a steady continent in late Paleozoic era, but was turned quickly into an active continental margin after the middle Jurassic period.     

江西省冬季大雪气候概况和环流特征分析

利用NCEP2．5°×2．5°再分析资料和常规观测资料,对1980--2008年江西省50次区域性大雪过程的气候概况、环流演变、热力层结、影响系统特征进行归纳分析。结果表明,江西省冬季大雪具有明显的年际、月际变化特征,冷冬年为大雪天气的多发年,进入暖冬期后,则有减少的趋势;空间变化上,出现大雪的频次基本上呈现出自西北向东南逐渐减少的特征,各地区积雪分布极不均匀。大雪期间,极涡、阻塞高压异常强而稳定,中低纬锋区异常强盛;超长波的稳定形势有利于天气背景的维持,造成连续性大雪。有80％的比例存在阻塞高压,以贝加尔湖阻塞高压最多;有70％的比例是受南支槽影响,当南支槽与中高纬度转竖的横槽同位叠加时,有利于引导极地强冷空气向副热带地区爆发,形成江西大范围降雪天气。对流层中低层多存在切变线,雪区位于冷式切变线以南1—3个纬距内或暖式切变附近,雪区伴随着暖切的南移而扩展;700hPa西南气流强盛,急流轴最大风速超过16m／s;当850hPa同时存在切变线时,降雪天气更剧烈。有98％的比例对流层中低层存在逆温,逆温高度平均在700-925hPa;温度垂直分布一般具有1000hPa温度≤0℃,925—850hPa温度≤-2℃,700hPa温度≤-2℃的特点。地面冷空气多为中路,蒙古冷高压异常强大,为降雪的产生创造良好的热力条件。     

新疆白石头泉高铷氟花岗岩不同相带云母成分及其演化

白石头泉含黄玉花岗岩体在露头上显示很好的岩性分带,从下至上依次为:淡色花岗岩(a带)、含天河石花岗岩(b带)、天河石花岗岩(c带)、含黄玉天河石花岗岩(d带)和黄玉钠长花岗岩(e带).岩体组成矿物主要为石英、钾长石(部分富铷的为天河石)、钠长石、黄玉和云母,副矿物为锰铝榴石和萤石.总体说来,从a带到c带,云母的Al、Mn、F和Rb含量递增,Fe、Mg和Ti含量递减;Li含量从a带到b带和c带递增,但b带和c带之间变化不明显.从c带到e带,随着Fe、Mg和Ti的减少,总体上表现为Al、Li递增,F、Mn和Rb递减的演化方向,但Li、F、Mn和Rb在c带和d带之间变化不明显,d带和e带之间却表现出急剧的变化.e带中的次生云母与原生云母相比,前者F、Li高而Al低,从a带到e带,Na K变化不明显.云母成分的这些变化特征与岩体的演化趋势相一致.白石头泉岩体与世界上其他地方类似花岗岩相比,没有出现锂云母这种高度富锂矿物,这可能与岩体中锂含量较低有关.     

成都地区土壤硼元素含量及其养分管理建议

成都地区浅层土壤中全量硼较为丰富,但是部分地区土壤有效硼较为缺乏。土壤中有效硼的含量与土壤有机质含量、pH值呈正相关,与土壤类型也有关系,而与硼全量关系不大。有效硼的缺乏主要是由于有机质缺乏、土壤pH值较低引起。黄壤地区酸性土壤种植油菜会有缺硼症状;水稻土和紫色土有效硼含量达到植物正常生长所需要的临界值,种植油菜就不缺乏硼,但是种植小麦仍然会缺硼。开展硼的区域生态地球化学评价时,不能只用土壤硼全量来评价其丰缺,还应该考虑用有效硼、有机质、pH值、土壤类型以及不同的植物种类等进行综合评价,更有利于指导农业生产土壤养分管理和选择种植适宜的植物。增加土壤有效硼含量的主要措施是施用硼肥,同时施用有机肥,酸性土壤适量施用石灰。     

一种北京城区避难场所可达性评价方法

针对传统两步移动搜寻法应用于避难场所可达性研究中存在的中心供给、统一阈值及无距离衰减的问题,提出了"入口供给、分段阈值、高斯距离衰减"的优化方案。入口供给更符合人类的认知规律,分段阈值则充分考虑了避难场所的面积因素,高斯距离衰减符合可达性随距离递减的规律。改良两步移动搜寻法能够较好地揭示城市应急避难场所与人口相互作用的规律。基于ArcGIS平台,将改良两步移动搜寻法应用于北京城区应急避难场所的可达性研究,获得更加真实、可靠的评价结果,展现了改良两步移动搜寻法在公共服务空间可达性评价方面的重要作用。     

全球变化下跨境水资源理论与方法研究展望

全球变化影响下,水危机位列未来10年世界风险之首,以国际河流区的跨境水纠纷及其导致的地缘战略竞争最受关注。科学调控跨境水安全,保障国家水权益,面临诸多科学与技术难题。回顾了国际河流水安全与水权益保障的研究进展,判识了存在的问题及面临的挑战。围绕创建全球变化下跨境水资源利益共享理论与方法体系研究目标,提出了需要解决的关键科学问题、技术瓶颈和创新思路;设置了主要研究目标与内容、总体方案与技术路线。这些研究,将推进国际河流水科学研究发展,提升全球变化下中国管控跨境水安全风险、保障国家水权益的科技支撑能力。     

自重体积力作用下坡体张应力及坡面位移的变化规律

为了提高对边坡体力学行为的认识,借助于FLAC有限差分软件的数值模拟,并结和相似理论的推导验证,研究了在仅有自重体积力作用的条件下,线弹性边坡体的一些力学特征及其与相关变量或物理力学参数的相关关系。没有外载荷影响时边坡地表最大主应力和最小主应力分别平行和垂直于地表,当深度增加时,主应力的取向逐渐变成竖直和水平两个方向,坡面处既有张应力区也有拉应力区,坡脚处亦存在较大的张应力,这是自重体积力作用下边坡体应力分布的一般性特征,在本文和前人的研究中都能体现。本文还重点揭露了:坡角线性增加时坡顶最大张应力的变化速率表现为:快慢快; 沿坡顶面竖直向下张应力随深度增加线性减小; 小变形条件下边坡应力场与弹性模量无关; 最后验证了满足相似理论的坡体,坡面对应点的位移比是其几何尺寸比的平方倍。本文不仅是对既有研究成果的进一步补充,而且为以后研究复杂条件下边坡体的力学特征奠定了基础,对于理论和实践都有一定的启发意义。