Controls on low-pressure anatexis   总被引：2，自引：0，他引：2  

C. C. GERBI  S. E. JOHNSON  P. O. KOONS 《Journal of Metamorphic Geology》2006,24(2):107-118

Low-pressure anatexis, whereby rocks melt in place after passing through the andalusite stability field, develops under more restricted conditions than does low-pressure metamorphism. Our thermal modelling and review of published work indicate that the following mechanisms, operating alone, may induce anatexis in typical pelitic rocks without inducing wholesale melting in the lower crust: (i) magmatic advection by pervasive flow; (ii) crustal-scale detachment faulting; and (iii) the presence of a high heat-producing layer. Of these, only magmatic advection by pervasive flow and crustal-scale detachment faulting have been shown quantitatively to provide sufficient heat to cause widespread melting. Combinations of the above mechanisms with pluton-scale magmatic advection, shear heating, removal of the lithospheric mantle, or with each other provide additional means of developing suitable high temperatures at shallow crustal levels to generate low-pressure anatexis.  相似文献   

重力取样器取样技术研究          下载免费PDF全文

毛志新  刘宝林  夏柏如 《探矿工程》2006,33(2):52-53,62

在湖泊环境研究中，淤泥质沉积物取样是一项很重要的工作，样品的取心率和原状性直接影响了环境研究的结果。重力取样器是获取湖泊、水库等水域浅层湖泊沉积物的一种经济有效、操作简单的常用工具。因此研究重力取样器的取样技术对环境研究具有积极的意义。研究了重力取样器的取样技术，并在此基础上成功设计了一种便携式的重力式取样器，非常适合环境研究机构的沉积物取样工作。  相似文献   

青藏高原中东部水热条件与NDVI的空间分布格局   总被引：5，自引：1，他引：5  

张文江  高志强 《地理研究》2006,25(5):877-886

青藏高原受大气环流和地势格局的共同作用,水热条件及植被空间分布呈现独特的三维地带性特征。但是青藏高原范围广、地势起伏大,水热条件及植被空间分布具有明显区域差异。本文利用青藏高原中东部100个气象站1982²000年的降水、气温资料以及同期NO-AA AVHRR植被指数产品（NDVI）,分析水热条件及植被的空间分布特征。首先,设置经向、纬向海拔渐变样带,考察海拔对水热条件及NDVI空间分布的影响;然后,按500米海拔间隔进行站点分组,分析约束了海拔高差后的经纬位置对水热条件及NDVI空间分布的影响。研究表明:在青藏高原中东部由于海拔高差大,热量条件分布首先受海拔递减规律控制,其次才表现出因太阳辐射差异的纬度地带性;而降水分布则主要受水汽通道位置和方向的影响,北上水汽和东部偏南走向山脉是研究区降水经向特征的主要成因;指示植被状况的年均NDVI,则受水热组合的控制,其分布格局是二者的叠加与综合。  相似文献   

新疆和田河水资源利用与绿色走廊生态建设研究   总被引：2，自引：0，他引：2  

阿布都热合曼·哈力克  克力木江 《地域研究与开发》2006,25(2):111-114

水是和田河绿色走廊形成与演变最重要的因素。虽然和田河径流量年际变化比较平稳．但年内径流量洪枯季节差异十分悬殊，人工调配水资源的难度较大。随着人类开发利用水资源规模扩大．水资源时空分布格局发生变化，中上游人工绿洲面积扩大，下游绿色走廊植被衰竭，土地荒漠化日趋严重，走廊生态环境持续恶化。文章分析了和田河水资源变化对下游绿色走廊兴衰的影响过程，提出了合理利用水资源、保护绿色走廊生态环境的对策建议。  相似文献   

1990～2003年洪湖水体环境质量演变分析   总被引：16，自引：0，他引：16  

胡学玉  陈德林  艾天成 《湿地科学》2006,4(2):115-120

以详细的水质监测资料为基础,采用标准指数法并结合实地调查,分析了1990~2003年洪湖水质的变化状况。结果表明,14 a间,洪湖水质类别以Ⅲ类和Ⅳ类为主。水质恶化的驱动因子是氮、磷及其它有机污染物。1991年到1994年期间,水体中氨氮(NH4 -N)占溶解无机氮(D IN)的比例逐年增高;1995~2003年,以氨氮和硝酸盐(NO3--N)同时作为水体中溶解无机氮的主要存在形式,与1990~1994年的水质状况相比,亚硝酸盐(NO2--N)所占的比例呈增加之势。氨氮、硝酸盐和亚硝酸盐的年际变化表明,洪湖水体自净能力在逐渐降低。以总磷(TP)、总氮(TN)和溶解无机氮(D IN)作为评价指标,洪湖水体已属中富营养型湖泊。洪湖水质演变与该区域人类活动(围湖造田、围网养殖等)以及江湖连通的变化对水环境的作用相耦合。  相似文献   

煤炭城市生态环境可持续发展研究--以淮南市为例     

邢琴琴  焦华富  尹乐 《世界地理研究》2006,15(2):54-60

根据城市生态学原理和方法,针对煤炭城市生态环境特点,构建了能够体现煤炭城市生态环境质量主要特征的,定性、定量考核的评价指标体系。利用层次分析、变权综合指数等方法,建立了煤炭城市生态环境质量综合评价模型。从自然、经济、社会三个方面对淮南市生态环境质量进行评价,并对淮南市生态环境可持续发展提出了相应对策。  相似文献   

Speciation analysis and significance of ecological geochemistry     

Yaping WANG Chunxue XU Ziyi AN Suming WANG 《中国地球化学学报》2006,25(B08):205-205

Different species of one element have different activities, so it has different effects on environment and human health. To analyze qualitatively and quantitatively the speciation of a special element in sample, which is the important basis for appraising the toxicity and studying the rule of transfer and translation of elements. Since the 1970＇s, the scheme of sequential extraction has already been used at many laboratories both at home and abroard, to get the information about heavy metals＇ activity in polluted soils. Because this method has the experimental nature, many schemes of problem has taken place, the absence of consistency of these sequential extraction have been formed. Thus the complexity of the schemes, the lack of selectivity of reagent, the lack of quality control, the result mainly related to the extraction scheme used, and so on. In the face of these problems, the study of experimental methods of sequential extraction on three different soils, sediment in Dongting Lake, soil in Jiangsu Province and loess in Shanxi Province was made. Reference materials of heavy metal speciation following sequential extraction in soil and sediment had been developed. Nowadays two kinds of sequential extraction methods which are widely used are BCR （three steps） and improved Tessier methods （seven steps）. Based on three steps of BCR, water-soluble speciation and the residual speciation were increased in our research. BCR701 was determined eight times at different laboratories using BCR three steps. The results showed that determined data obtained eight times were identical to the standard value, and it is indicated that this method has good reproducibility. The stability and homogeneity experiments indicated that the preparation of three types of candidates accorded with our requirements. Eight laboratories had afforded the determined values of 12 heavy metal elements （Cu, Pb, Zn, Mn, Co, Ni, Cd, Cr, Mo, As, Sb, Hg, Se et al.） using BCR three steps. Also, these three candidates afforded the determined values by seven steps, and 12 laboratories had participated.  相似文献   

长江三角洲土壤质量演变趋势分析   总被引：9，自引：1，他引：9  

吴新民  潘根兴  李恋卿 《地理与地理信息科学》2006,22(3):88-91

对长江三角洲地区近20年来土壤质量演变趋势分析得出:研究区土壤肥力质量总体呈上升趋势。土壤有机质含量先降后升;全N、速效N含量分别呈S型、直线上升趋势,局部地区有积累趋势;速效K和土壤pH值下降明显;土壤盐基交换量(CEC)有增高趋势。土壤环境负荷呈增大趋势,表现为土壤氮、磷出现季节性盈余,对水体富营养化贡献率大;土壤重金属有明显积累特征;土壤有机磷、有机氯等农药、除草剂、表面活性剂在生态链中仍有一定影响。  相似文献   

绿色建筑的内涵及其发展的若干思考     

罗栋燊  廖福霖  官巧燕  郑国诜 《福建地理》2006,(4)

随着我国城市化进程的快速推进,大规模的人居环境建设使我国的资源与环境面临巨大的挑战,发展绿色建筑已经成为可持续发展的重大战略问题.文章从可持续发展的角度,指出了绿色建筑的内涵与特征,并归纳了绿色建筑与一般建筑的区别.在此基础上,提出了发展绿色建筑的具体对策.  相似文献   

Glacial survival of blockfields on the Varanger Peninsula, northern Norway     

Jakob Fjellanger  Leif Srbel  Henriette Linge  Edward J. Brook  Grant M. Raisbeck  Franoise Yiou 《Geomorphology》2006,82(3-4):255-272

For more than hundred years it has been debated whether blockfields in mountain summit areas can be used to delimit the vertical extent of Pleistocene ice sheets. In this study the relationship between blockfields, developed in quartzites and sandstones on the Varanger Peninsula, northern Norway, and glacially derived features have been evaluated. Erratics and circular ablation moraines are superimposed on the blockfields and lateral meltwater channels are eroded into them. Glacial striations and other signs of glacial sculpturing are restricted to low-lying areas with channelled ice flow. Relative ages of the blockfields and the features in them are inferred, and the first measurements of in-situ produced cosmogenic nuclides from the Varanger Peninsula are reported. We conclude that the blockfields have survived underneath at least one thick, cold-based ice sheet. Thus, these blockfields cannot be used as indicators of ice-free conditions as previously suggested for southern Norway. Our results have implications for the potential for land surface preservation beneath ice sheets and for glacial reconstructions in northern Fennoscandia.  相似文献