High-resolution sedimentary record of lead in the coastal mud of the East China Sea in the past one hundred and fifty years     

Yunchao HAO Zhigang GUO Dejiang FAN 《中国地球化学学报》2006,25(B08):13-13

In the East China Sea （ECS）, there are some mud areas, including the south coastal mud area, the north coastal mud area, and the mud area to the southwest of Cheju Island. X-ray fluorescence （XRF） techniques and Thermal Ionization Mass Spectrometry （TIMS） were used to study the high-resolution sedimentary record of Pb concentrations and Pb stable isotopic compositions in the past one hundred and fifty years in the coastal mud of the ECS. Pb concentrations of a ^210Pb dating S5 core in the study area have increased rapidly since 1980, and reached the maximal value with 65.08 μg/g in 2000, corresponding to the fast economic development of China since the implementation of the ＂Reform and Open Policy＂ in 1978; ^206Pb/^207Pb ratios generally had stabilized at 1.195 from 1860 to 1966, and decreased gradually from 1966 to 2000, indicating that the anthropogenic source Pb contribution to the ECS has increased gradually since 1966, especially since 1980. Pb concentrations decreased distinctly from 2000 to 2003 and ^206Pb/^207Pb ratios increased from 2001 to 2003, corresponding closely to the ban of lead gasoline from 2000 in China. From 1950 to 2003, there occurred four distinct decrease events of ^206Pb/^207Pb, possibly responding to the Changjiang River （Yangtze River） catastrophic floods in 1998, 1991, 1981 and 1954; from 1860 to 1966, there were two decrease periods of ^206Pb/^207Pb, which may respond to the catastrophic floods of Changjiang River in 1931 and 1935, and 1870. As a result of the erosion and drowning by the catastrophic floods, the anthropogenic lead accumulated in soil and water environments over a long period of time was brought into the Changjiang River, then part of them was finally transported into the ECS, which leads to changes in Pb stable isotopic composition.  相似文献   

复合土钉墙支护技术在某大型软土基坑围护中的应用          下载免费PDF全文

杜常春  章泽军  李飞  周喜锋 《探矿工程》2006,33(2):26-29

根据拟建建筑基坑的工程地质条件、周边环境条件、基坑开挖深度等特点综合考虑，对基坑分段采用超前微型桩支护加土钉墙、放坡加土钉墙2种复合支护方案。实践证明，该工程所采用的多种复合式支护实施方案，技术安全可靠，经济合理。  相似文献   

2004–2005 Analytical Developments in Secondary Ion Mass Spectrometry     

Etienne Deloule 《Geostandards and Geoanalytical Research》2006,30(3):175-182

This review of the literature from 2004 and 2005 concerning secondary ion mass spectrometry (SIMS) highlights the contribution the technique has made in the fields of petrology, geochronology, cosmochemistry and material sciences. In petrology, much research was devoted to the measurement of stable isotopes and trace elements by developments in multicollection acquisition, with emphasis on low atomic mass number elements. Elements studied in particular were S (in sulfides), O (in garnets), C (in sedimentary organic matter), Cl (in glasses) and Si. Novel applications of SIMS to geochronology have included the measurement of young zircon grains by the U-Pb and U-Th decay methods. An increasing number of studies have combined U-Pb geochronology with the measurement of trace elements or stable isotopes in zircon.  相似文献   

湘阴县氏族移民地理研究（121¹735年）     

龚胜生  于颖 《地理研究》2006,25(6):1096-1106

历史人口迁移是历史时期区域人地关系演变的最直接的动力。通过对121¹375年间湘阴县外来氏族移民过程与空间分布的分析,发现:他们无论是直接迁入还是辗转迁入,绝大多数都是为了土地和生存而来;67.2%的氏族祖籍江西,地缘上的亲和力和血缘上的凝聚力导致了氏族移民迁出地的邻近性和入居地的集聚性;69.6%的外来氏族在明代迁入,后唐同光年间,元末明初,明末清初为三个氏族移民高峰期;不同时期有着不同的氏族移民来源地,不同时期的氏族移民入居到不同的地理空间。随着时间的推移,湘阴县氏族移民入居地从丘陵平原向河湖滩地拓展的演变,反映了湘阴县域乃至整个洞庭湖区从丘陵到平原再到湖区的区域开发过程。  相似文献   

山区生态县区域协调发展的机制构建--以粤北始兴县为例   总被引：1，自引：0，他引：1  

税伟  陈烈  唐常春 《山地学报》2006,24(1):70-78

区域协调机制在不同类型地域和一种类型地域的不同的发展阶段是不同的。始兴县作为一个典型的山区生态县,工业进入加速发展时期,在此经济发展阶段的区域协调问题主要表现在:与外部区域经济、社会发展差距拉大,工业化与流域生态环境保护的矛盾已开始凸现,县政府协调区域发展的财政能力较低,区域协调机制不健全等。由此对始兴县的区域协调机制进行建构:建立健全多层次的区域协调机构;加大纵向和横向政府财政转移支付的力度;加强与相邻相关地区的协调;实施区域空间管治协调,保护城乡生态环境;科学合理选择产业,大力发展循环经济;全县推行绿色GDP考核等。  相似文献   

长白山锦北雨养泥炭剖面元素富集规律分析   总被引：3，自引：2，他引：3  

贾琳  王国平  刘景双 《湿地科学》2006,4(3):187-192

为了揭示长白山锦北泥炭沼泽区泥炭沉积环境和重金属元素的历史变化及其对环境的指示意义,利用荷兰W ardenaar泥炭采样器采取泥炭样品并对样品进行高分辨率切割。用原子吸收分光光度计和等离子体发射光谱仪测定不同深度剖面Ca,Mg,Na,K,A l,Ti,Cu,Zn,Fe,Mn,Pb,Cr,N i和Co的浓度。研究分析了Ca,Mg,Na,K,A l,Ti,Mn,Zn,Cu,Pb,Cr,N i和Co在泥炭剖面的分布趋势并对其进行了相关分析和富集分析,得出Mn,Zn,Cu,Pb,Cr,N i和Co呈显著相关且在泥炭表层明显累积,揭示出泥炭表层重金属元素的大气沉降来源,表明近年来人类重金属消耗量及排放量的增加是大气沉降重金属元素的主要释放源,而且环境中重金属污染有加重的趋势。  相似文献   

Mercury contaminations to the ambient air, soil and water compartments in the zinc smelting area in Weining County, Guizhou, China     

《中国地球化学学报》2006,25(B08):241-241

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金沙江干热河谷区土壤侵蚀危险度评价——以云南元谋为例     

周红艺  熊东红杨忠 《山地学报》2006,24(B10):52-56

利用空间主成分分析方法，选取降水、坡度、植被、土地利用、土壤类型、人口、高程等作为评价指标，建立空间主成分评价模型Pi=0．78X1＋0．06X2＋0．05X3＋0．04X4，将研究区分为无险型、轻险型、危险型、强险型和极险型五种类型，较为准确地得到了危险度综合评价结果。因此，空间主成分分析模型，在土壤侵蚀危险程度评价方面的应用较为成功，是一种科学有效的研究方法。  相似文献   

Estimating the minimum in-stream flow requirements via wetted perimeter method based on curvature and slope techniques     

LIU Suxia  MO Xingguo  XIA Jun  LIU Changming  LIN Zhonghui  MEN Baohui  JI Lina 《地理学报》2006,16(2):242-250

Under the assumptions of triangular cross section channel and uniform stable flow, an analytical solution of the minimum ecological in-stream flow requirement (MEIFR) is deduced. Based on the analytical solution, the uncertainty of the wetted perimeter method is analyzed by comparing the two techniques for the determination of the critical point on the relationship curve between wetted perimeter, P and discharge, Q. It is clearly shown that the results of MEIFR based on curvature technique (corresponding to the maximum curvature) and slope technique (slope being 1) are significantly different. On the P-Q curve, the slope of the critical point with the maximum curvature is 0.39 and the MEIFR varied prominently with the change of the slope threshold. This indicates that if a certain value of the slope threshold is not available for slope technique, curvature technique may be a better choice. By applying the analytical solution of MEIFR in the losing rivers of the Western Route South-to-North Water Transfer Project in China, the MEIFR value via curvature technique is 2.5%-23.7% of the multi-year average annual discharge, while that for slope technique is 11%-105.7%. General conclusions would rely on the more detailed research for all kinds of cross-sections.  相似文献   

Modification of streaming potential by precipitation of calcite in a sand–water system: laboratory measurements in the pH range from 4 to 12     

Xavier Guichet  Laurence Jouniaux  Nicole Catel 《Geophysical Journal International》2006,166(1):445-460

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