胶州湾浮游植物分子遗传多样性初步研究   总被引：1，自引：0，他引：1  

刘永健  杨官品  门荣新 《中国海洋大学学报(自然科学版)》2003,33(6):907-916

用聚合酶链式反应扩增海洋浮游植物总体的核酮糖 1 ,5 -二磷酸羧化 /氧化酶大亚基基因(rbc L)片段 ,建立该基因变异类型文库 ,并随机测定了 38个 rbc L大亚基基因片段序列 ,初步分析了海洋浮游植物分子遗传多样性。将≥ 97%的氨基酸序列相似性定义为种内变异 ,38个片段分别代表1 3个不同的物种 ,或称为不同的操作分类单元。与数据库序列比较发现 ,PPJZ0 1 ,PPJZ1 1和 PPJZ2 0可能是已报道的 rbc L基因序列代表的物种 ,其它克隆在数据库中没有对应的近缘物种序列存在。系统学分析表明分离的克隆分别属于隐藻门、硅藻门、绿藻门和 streptophyta等的浮游植物 ,极少数克隆来源于异鞭毛藻类、定鞭藻纲和原细菌。根据各操作分类单元克隆数计算得胶州湾浮游植物分子遗传多样性指数为 1 .97。研究结果为利用分子生物学方法剖分海洋浮游植物群落结构、研究海洋浮游植物动力学积累了基础数据  相似文献   

The 2015 Nepal M8.1 earthquake and the prediction for M ≥ 8 earthquakes in West China     

Ke-Pei Men  Kai Zhao 《Natural Hazards》2016,82(3):1767-1777

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δ13C-δ18O Covariance: An Effective Indicator of Hydrological Closure for Lakes?     

CHEN Jing’an  WANG Fushun  WAN Guojiang  TANG Degui  David Dian ZHANG  HUNAG Ronggui  LI Jian  XIAO Tangfu 《《地质学报》英文版》2008,82(5):975-981

The correlation between the δ^13C and δ^13C-δ^18O in primary carbonates is affected by several factors such as hydrological balance, total CO2 concentrations, climatic condition and lake productivity. The influence of these factors on the δ^13C-δ^18O correlation may be different on different time scales. In this paper, two different-type lakes in southwestern China, Lake Erhai and Lake Chenghai, are selected to investigate the influence of climatic pattern on the δ^13C-δ^18O correlation and to evaluate the reliability of the δ^13C-δ^18O covariance as an indicator of hydrological closure. The results show that there exists good correlation between the δ^13C and δ^18O in Lake Erhai （overflowing open lake） and in Lake Chenghai （closed lake）. This suggests that the δ^13C-δ^18O covariance may be not an effective indicator of hydrological closure for lakes, especially on short time scales. On the one hand, a hydrologically open lake may display covariant δ^13C and δ^18O as a result of climatic influence. The particular alternate warm-dry and cold-wet climatic pattern in southwestern China may be the principal cause of the δ^13C-δ^18O covariance in Lake Erhai and Lake Chenghai. On the other hand, a hydrologically closed lake unnecessarily displays covariant trends between δ^13C and δ^18O because of the buffering effect of high CO2 concentration on the δ^13C shift in hyper-alkaline lakes. We should be prudent when we use the covariance between δ^13C and δ^18O to judge the hydrological closure of lake.  相似文献   

Feasibility Analysis of the Use of Binary Genetic Algorithms as Importance Samplers Application to a 1-D DC Resistivity Inverse Problem     

J. P. Fernández Alvarez  J. L. Fernández Martínez  C. O. Menéndez Pérez 《Mathematical Geosciences》2008,40(4):375-408

DC resistivity inverse problems are ill-posed. For the Vertical Electrical Sounding method the acceptable solutions lie in very narrow elongated-shape regions in the model space. To characterize this ensemble of solutions is a central question. In a Bayesian framework this issue is solved adopting as solution the so-called model posterior probability distribution. However, due to the nonlinearity of the problem, this distribution is not explicitly known, or it is difficult to calculate. Therefore, algorithms that efficiently sample the model space according to it (importance sampling) are very desirable. The main goal of this paper is to numerically explore the performance of binary genetic algorithms as posterior importance sampling strategies. Their behavior will be firstly analyzed using 2D synthetic posterior test functions bearing the relevant properties of the real geo-electrical inverse problem. The conclusions will be again checked through the histogram reconstruction of parameters in a synthetic VES case, and eventually, in a real, higher dimensional, sea-water coastal intrusion problem, by comparing the results with those obtained with a theoretically correct Metropolis-Hasting importance sampler (simulated annealing without cooling). Percentile curves are introduced as an effective tool for risk assessment. We show that binary genetic algorithms perform well under very general assumptions. When the roulette wheel is the selection method used, mutation is over 10%, and the algorithm does not incorporate elitism. The results do not depend on the values of the remaining tuning parameters. Finally, to improve the efficiency of the sampling strategy, we introduce a binary genetic algorithm with oriented search space. This is done with the help of linearization of the forward operator and singular value decomposition around the maximum posterior estimate. It is shown, also, that the logarithmic model parameterization is adequate for this task.  相似文献   

Present geotemperature and its suggestion to natural gas generation in Xujiaweizi fault-depression of the northern Songliao Basin     

QingHua Zhou  ZiHui Feng  GuangTian Men 《中国科学D辑(英文版)》2008,51(1):207-220

According to stastistic of present geotemperatures at the depths of 1000, 2000, 3000 and 4000 m, respectively in the Xujiaweizi fault-depression of the north Songliao Basin, the result indicates that Xujiaweizi fault-depression falls in the high geotemperature area, with the higher geothermal gradient in the depression layer than that in the fault-depression layer. The geothermal gradient decreases with the increasing of the depth. The thermal conductivity of rock greatly controls the geothermal gradient. The main factors constraining the current geotemperature include thermal configuration of the earth’s crust, deep faults, distribution and abundance of radioelements. The high geotemperature is in favour of generation of deep gas.  相似文献   

毛乌素沙漠砂土地基处理效果分析     

门青波  夏玉云  吴兴辉 《岩土工程技术》2012,26(2):74-77,85

在对毛乌素沙漠南缘风积砂进行水坠砂（静水沉积和浸水饱和分层碾压）、振冲密实法（振冲砂桩）及强夯等现场试验的基础上,对不同地基处理方式后风积砂的物理特性和地基承载力进行了对比分析,提出了风积砂不同地基处理方式的优缺点,并对不同地基处理方式的机理进行了探讨。  相似文献   

强夯法加固砂土地基效果的检测分析     

吴兴辉  门青波  常玉娟 《岩土工程技术》2014,28(6):287-290

针对强夯法在加固效果的检测与评价方面较为欠缺这一现状,结合工程实例,对某强夯加固砂土地基与天然状态砂层采用多种方法进行检测和对比分析,对强夯法加固的砂土地基做出了比较客观的评价,并探讨了影响强夯加固效果的因素。为强夯法加固砂土地基的检测积累了经验,对提高强夯法在设计、施工中的应用具有重要的理论价值和现实意义。  相似文献   

黔中气溶胶传输的210 Pb和7 Be示踪:Ⅱ.月及年时间尺度的剖析     

万国江  郑向东  Lee H N  Bai Z G  万恩源  王仕禄  杨伟  苏菲  汤洁  王长生  黄荣贵  刘鹏 《地球科学进展》2010,25(5):505-514

自2001年12月连续逐周在贵阳观风山附近对近地面空气210Pb-7Be浓度和沉降量的观测表明:区域性降水和气温制约近地面空气210Pb具高浓度"U"型年分布;降水量和平流层向下输送影响近地面空气7Be月均浓度的季节性变化;210Pb/7Be月均浓度比率受控于210Pb变化和富7Be气团下沉的影响.观风山与瓦里关山之间因纬度和海拔的关系,7Be比率急剧震荡,显示出海洋性贫7Be气团入侵对观风山地区的明显影响.2002-2008年间贵阳观风山近地面空气210Pb的年均浓度(2.8±0.6)mBq/m3,约为全球若干站点中最高平均浓度值的4倍;而7Be的年均浓度(4.8±0.6)mBq/m3,与全球高海拔站点长期观测的平均值相当,大约为北半球中纬度对流层顶部附近7Be浓度值(18.0 mBq/m3)的1/3.8,显示出低纬度、较高海拔地区的预期水平.2003年,瓦里关山和观风山近地面空气7Be的年均浓度比为3.8,与预期的大气输送和混合作用基本一致.7Be月均浓度的增大趋势反映出受太阳黑子数减少的变化关系,其影响底线大约为4 mBq/m3;7Be年均浓度波动的增大趋势反映出受太阳黑子数降低的可能影响.贵阳观风山降水中7Be和210Pb的体积加权浓度分别为0.72 Bq/L和0.27 Bq/L;年沉降通量分别为0.080 Bq/(cm2·a)和0.031 Bq/(cm2·a).数值模拟显示出全球空气210Pb高浓度区和高沉降通量环带分布,印证了洱海和红枫湖沉积物7Be和157Cs蓄积的模拟结果.  相似文献   

黔中气溶胶传输的210 Pb和7 Be示踪:I.周时间尺度的解释     

万国江  郑向东  Lee H N  Bai Z G  万恩源  王仕禄  杨伟  苏菲  汤洁  王长生  黄荣贵  刘鹏 《地球科学进展》2010,25(5)

认识环境核素在不同地域空气中的浓度分布和沉降到地表环境的通量对气溶胶污染物全球扩散模型的建立和验证、沉积过程示踪和沉积计年、流域侵蚀示踪参比,以及生态系统受天然辐照的评价等多个领域都是关键的依据.自2001年以来在贵阳观风山等地逐周连续采样,对近地面空气和降水中210Pb和7Be浓度的观测结果表明:①因气象条件变化,近地面空气210mPb和7Be周浓度具有2～6周变幅不等的短周期波动.210Pb空气浓度在年内的总趋势呈现出受气温变化的总体影响和降水的短暂调控;而7Be空气浓度出现连续不断的峰-谷交替.②两核素在近地面空气周浓度的低值同步,210Pb/7Be比率较高(≥0.8),显示出海洋性贫210Pb-7Be气团的入侵影响;它们高的周浓度也同步耦合,比率较低(≤0.7),显示出高层大气富7Be气团的输入.③210Pb和7Be的周降水浓度及水-气分配系数在秋末春季较高,而春末-秋季明显偏低.周降水浓度随同期空气浓度呈增高趋势,其季节分界分别为0.2 Bq/L和1 Bq/L;而Kd值随同期空气浓度增大呈降低趋势.210Pb和7Be的降水沉降主要分布在每年的春夏季;周沉降量随同期降水量呈增大趋势,7Be增大的斜率约为210Pb的3倍;当近于零降水时,它们在降水中的初始比率约为2.5.它们出现高或者较高的周降水沉降都伴随当周或邻周空气浓度的急剧下降;降水中210Pb/7Be比率主要分布在≤0.5,并与空气中210Pb/7Be比率基本同步,显示出两核素被降水清洗的效率基本相近.④2008年冰冻极端天气过程中,210Pb-7Be空气浓度同步低谷并存在气溶胶低浓度与高比活度耦合.⑤观风山7Be周空气浓度显示低纬度、较高海拔地区的预期水平;短周期波动反映强下沉气流和低海拔上升气团影响分别在观风山和瓦里关山的滞后性.  相似文献   

The preg-robbing of gold and silver by clays during cyanidation under agitation and heap leaching conditions     

J. Tremolada  R. Dzioba  A. Bernardo-Sánchez  J.M. Menéndez-Aguado 《International Journal of Mineral Processing》2010,94(1-2):67-71

Laboratory scale leaching tests were carried out in different experimental conditions, with monitoring of gold and silver recovery, the concentration of cyanide used in leaching, solution pH, and precious metal adsorption onto clay. Evidence for the adsorption or re-precipitation of gold from cyanide solutions onto clay minerals is conclusive and indicates that adsorption contributes to the total gold loss from conventional cyanidation. The loss is related to the type of clay, and appears to be affected by the extent of time cyanidation. It was observed that silver adsorption capacity was above 80% and that the degree of adsorption for gold oscillated between 1.68% and 7.49%, depending on the type and characteristics of the evaluated clay.  相似文献