京九铁路赣南段可能发生地质灾害的典型路段分析及减灾对策     

应丽君 《江西地质》1997,11(4):71-74

本文结合赣南环境工程地质条件，对京九铁路赣南段可能发生地质灾害的典型地段进行分析，并提出了减灾对策  相似文献   

The Source of Silica and Trace Metals in Particulate Matter in Framvaren Fjord     

David W. Dyrssen 《Aquatic Geochemistry》1997,3(4):329-343

The lake and streams in the Framvarenwatershed were sampled and analyzed in September 1983.The results can be explained by the precipitation ofacid rain containing some sea salts and thedissolution of Farsundite, the dominating rock in thecatchment area. The runoff supplies the surface waterof Framvaren with silica, aluminium, manganese, iron,copper, zinc, cadmium and lead. Reasonablecalculations show that the runoff most likely is themain source for the particulate matter found insediment traps and by filtering off suspendedparticles. Thus the calculations supplement recentstudies of Skei et al. (1996). This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

催化还原褪色光度法测定痕量锡   总被引：7，自引：1，他引：6  

周之荣 《岩矿测试》1998,17(4):279-281

痕量锡在０．０４ｍｏｌ／ＬＨ３ＰＯ４介质中对ＮａＨ２ＰＯ２还原罗丹明Ｂ褪色反应有催化作用,催化程度与Ｓｎ量、温度和加热时间线性相关。基于此,建立了痕量锡的动力学光度分析方法。方法检出限为０．０３４μｇ／Ｌ,线性范围为０～２０μｇ／Ｌ,结合磷酸三丁酯色谱分离,实现了地质样品中痕量Ｓｎ的测定。方法经国家地质标准物质分析验证,结果与标准值相符。对于ｗ（Ｓｎ）为１０－６水平的试样其ＲＳＤ（ｎ＝６）＜６．５％。  相似文献   

乳山湾的污染与异养微生物的调查分析     

陈世阳  包文雅  李八方  刘树青 《中国海洋大学学报(自然科学版)》1987,(4)

于1985年5—10月定期采取了乳山湾内和岸边养虾池的水样及底泥进行了异养微生物的分析。菌数的平均值池内高于湾内,其最高值和水中COD的最高值同时出现在养虾旺季的8月份。在湾泥和池泥中的硫酸盐还原菌数均高达10~6个/克以上,与同期内硫化物的最高含量(326mgS/kg)相一致。并发现病原性弧菌也广泛存生。异养菌种群的组成,假单胞杆菌占有最大的比值,反映出该水域为污染类型。上述结果表明该湾的水质条件已远超出国家渔业水质标准,呈现高度的有机物污染状态,其污染源与湾边周围开展大面积的养虾有关。  相似文献   

Archean Mass-independent Fractionation of Sulfur Isotope:New Evidence of Bedded Sulfide Deposits in the Yanlingguan-Shihezhuang area of Xintai, Shandong Province     

LI Yanhe  HOU Kejun  WAN Defang  YUE Guoliang 《《地质学报》英文版》2008,82(2):444-450

Multiple sulfur isotope ratios （^34S/^33S/^32S） of Archean bedded sulfides deposits were measured in the Yanlingguan Formation of the Taishan Group in Xintai, Shandong Province, East of China; 633S = -0.7%o to 3.8‰,δ^34S = 0.1‰-8.8‰, △^33S = -2.3‰ to -0.7‰. The sulfur isotope compositions show obvious mass-independent fractionation （MIF） signatures. The presence of MIF of sulfur isotope in Archean sulfides indicates that the sulfur was from products of photochemical reactions of volcanic SO2 induced by solar UV radiation, implying that the ozone shield was not formed in atmosphere at that time, and the oxygen level was less than 10-5 PAL （the present atmosphere level）. The sulfate produced by photolysis of SO2 with negative △^33S precipitated near the volcanic activity center; and the product of element S with positive △^33S precipitated far away from the volcanic activity center. The lower △^33S values of sulfide （-2.30‰ to --0.25‰） show that Shihezhuang was near the volcanic center, and sulfur was mostly from sulfate produced by photolysis. The higher △^33S values （-0.5‰ to -‰） indicate that Yanlingguan was far away from the volcanic center and that some of sulfur were from sulfate, another from element S produced by photolysis. The data points of sulfur isotope from Yanlingguan are in a line parallel to MFL （mass dependent fractionation line） on the plot of δ^34S--δ^33S, showing that the volcanic sulfur species went through the atmospheric cycle into the ocean, and then mass dependent fractionation occurred during deposition of sulfide. The data points of sulfur isotope from Shihezhuang represent a mix of different sulfur source.  相似文献   

逐步缩小搜索范围的遗传算法   总被引：16，自引：3，他引：16  

石琳珂 《地球物理学进展》1995,10(4):67-79

本文介绍在遗传算法的运行过程中如何逐步缩小搜索范围，使搜索速度与计算精度同时得到提高的方法。文中提出了真值邻域的概念，利用这个概念得到了缩小搜索范围的压缩公式。只要合理选择初始搜索范围（这一点并不难做到），上述压缩公式能确保问题的解始终保留在压缩后的搜索范围内。通过理论模型的检验及与原有遗传算法结果的比较，证实了方法的有效性。  相似文献   

扬子大陆的陆内俯冲与大陆的缩小──由白云母（二云母）花岗岩推导     

邓晋福  赵海玲  莫宣学  刘厚祥  罗照华 《高校地质学报》1995,(1)

本文简要地论述了白云母（二云母）花岗岩是陆内俯冲的岩石学记录。华南大陆与天水－雅江地带广泛分布中生代王云母花岗岩侵作入体，已有的同位素年龄范围为２４５～１２２Ｍａ，与此同时，它们两侧的扬子大陆发育前陆褶皱带，这种成对性及其构造配置表明，扬子大陆曾向华南大陆与松潘—甘孜褶皱带发生过陆内俯冲作用。基于二云母花岗岩带的总宽度（约６５０ｋｍ），估算扬子大陆最小的总俯冲量（指宽度）至少为６５０ｋｍ，扬子大陆现今宽度约６８０ｋｍ，这样，扬子大陆在中生代时期由于陆内俯冲作用缩小了约一半；另一可能方案是，消失的主要是夹持于扬子大陆与江南造山带之间的一个微大陆。扬子大陆与秦岭造山带之间的壳内构造边界不具陆内俯冲性质，而是逆冲推复一走滑构造带。在大地构造单元上，江南造山带与龙门山造山带应分属两个上叠大陆，而不属于扬子大陆。华南中生代造山带内侧属于高喜马拉雅型陆内俯冲带（缝合带内无蛇绿岩伴生），而不是雅鲁藏布江型（缝合带内有蛇绿岩伴生）。陆内俯冲作用是华南大陆形成的主要机制之一。此外，它经受过晚元古代和加里东期陆内俯冲事件，可能属于雅鲁藏布江型。多次陆内俯冲和白云母（二云母）花岗岩的形成导致亲陆壳金属元素富集，可能是华南Ｗ－Ｓｎ  相似文献   

Sulfur species variation controlled by sulfate reducing bacteria （SRB） in sediments of Lake Erhai     

《中国地球化学学报》2006,25(B08):147-147

  相似文献   

塔里木河下游不同覆盖度灌木防风固沙功能野外观测研究   总被引：8，自引：1，他引：8  

程皓  李霞  侯平  裴玉亮 《中国沙漠》2007,27(6):1022-1026

 对塔里木河下游50%、25%、10%三种覆盖度灌木降低风速观测结果表明: 50%覆盖度灌木降低风速最明显，防风效能为49.21%；25%的覆盖度灌木降低风速较明显，防风效能为24.44%;10%的覆盖度灌木对风速降低有一定作用，防风效能为9.15%。在7.7 m.s-1风速下，植被覆盖度为10%、25%的沙地输沙率分别是无植被覆盖沙地的62.44%和8.37%；在10 m.s-1风速下，植被覆盖度50%的沙地仅有轻微的风蚀。根据塔里木河下游不同覆盖度植被与降低风速之间的定量关系，得出不同风速条件下的有效植被覆盖率，在研究区常见10～15 m.s-1风速条件下，要达到有效阻沙效果，植被覆盖率应在50%以上。  相似文献   

System Performance in UASB Reactors Receiving Increasing Levels of Sulfate     

Dilek Erdirencelebi  Izzet Ozturk  Emine Ubay Cokgor 《洁净——土壤、空气、水》2007,35(3):275-281

Glucose‐fed high‐rate UASB reactors were tested at three COD/SO₄ ratios and hydraulic retention times to promote sulfate reducing activity and observe the effects on reactor performance. Different COD/SO₄ ratios (20, 10, and 5) resulted in changes in organic matter removal, methane production, alkalinity, dissolved sulfide and biomass concentrations and profile. The COD removal dropped from 95 to 80–84 % at the lowest COD/SO₄ ratio. Sulfate was removed at 79 to 89 % at the highest ratio and dropped to 72 to 74 % with increasing sulfate loading. Alkalinity was produced at higher levels with increasing sulfate loading. Specific methane production dropped with decreasing hydraulic retention times. Sulfate‐reducing activity used a maximum of 11.7 % of organic matter at the highest sulfate loading level, producing a slight shift to sulfate‐reducing activity in the substrate competition between sulfate‐reducing bacteria and methanogens. Increased sulfate loading at COD/SO₄ ratios of 10 and 5 caused deterioration of the concentration profile of the sludge, resulting in biomass washout and decreased volatile fraction of biosolids in the reactors.  相似文献