Different levels of macroalgal sampling resolution for pollution assessment

The effects of using reduced sampling resolutions to study macroalgal vegetation patterns have not been studied sufficiently. Here, we test the influence of taxonomic resolution level, removal of occasional species, aggregation of species abundances into functional groups and data transformation in the detection of a long-term recovery process by phytobenthic intertidal assemblages. Results indicate that the aggregation of species data into the genus level has very little influence. Likewise, almost any significant information is lost when occasional algae are removed. Analyses at the level of families and orders still clearly detect differences between highly degraded and reference vegetation. By contrast, analyses based on class and functional group abundances capture quite different information. The effect of transformation is similar at the different taxonomic levels. Most surrogate measures properly reflect changes in diversity. It is concluded that genus level is the most appropriate surrogate approach for detecting the recovery process.     

成组地震的应力场变化与前兆关系

综述了成组地震以及地震静应力触发方面的研究现状，并在此基础上讨论了：如何应用震后静应力变化研究成组地震前兆；如何区分地震组的前兆和组中单个地震的前兆。     

东昆仑格尔木南部纳赤台群和万宝沟群基质系统与外来系统地球化学差异

东昆仑造山带的纳赤台群和万宝沟群为沉积-构造混杂堆积,2个群可分为基质系统和外来系统截然不同的2部分。除了古生物的差别外,从所做地球化学分析来看,两系统的常量元素、微量元素、稳定同位素、稀土元素和Si同位素等分析数据显示两者之间的明显差异,表明它们分别来自不同的沉积环境。基质系统的地球化学指标指示了半深水—深水的外陆棚—斜坡相沉积环境,而外来系统的地球化学指标指示浅水台地相的沉积环境。     

干酪根分子结构在低熟阶段的演化特征：基于红外光谱分析

为研究低熟气形成过程中大分子结构的变化情况,对吐哈盆地侏罗系八道湾组的煤与碳质泥岩干酪根在不同升温速率下进行了热解实验,借助于红外光谱分析,研究了不同热模拟温度下干酪根结构的特征与变化。结果表明,随热演化的进行,煤与碳质泥岩干酪根的芳香结构不断缩合,含氧官能团不断脱落,碳质泥岩干酪根中的脂肪族类有所降低。吐哈盆地低熟气主要来源于煤与碳质泥岩干酪根中的含氧官能团--羧基与甲氧基,以及碳质泥岩干酪根上的脂肪族。从干酪根结构上揭示了低熟气主要来源于Ⅲ型有机质的原因。     

三峡水库香溪河库湾浮游植物功能群对水位变化的响应

三峡水库每年经历“水位下降(4—5月)-低水位(6—8月)-蓄水(9—10月)-高水位(11月—次年3月)”的季节波动,年水位落差达30 m。为探究香溪河库湾浮游植物功能群对三峡水库水位变化的响应,于2017年对浮游植物群落和主要环境因子开展逐月调查。共检出浮游植物7门65属79种,隶属于21个功能群,其中优势功能群10个,分别为C、D、F、G、J、Lo、M、P、X2、Y。适应营养丰富环境的C、P功能群在全年维持优势,指示香溪河库湾为中-富营养水体。消落期偏好水体扰动较弱、中-富营养水体的功能群(F、G、X2、Y)成为优势类群;汛期偏好稳定富营养、耐受高光强且对冲刷敏感的功能群(G J、M)成为优势类群;蓄水期和高水位运行期偏好混合的中-富营养水体,耐受低光强且对水体分层敏感的功能群(C、P、D)是优势类群;浮游植物功能类群组成结构随水位变化明显改变。综合营养状态指数表明香溪河库湾在消落期和高水位运行期处于中营养状态,另外两个时期处于富营养状态(39.84≤TSI_M≤60.9);Q指数表明香溪河库湾整体水质为“好”(3.02≤Q指数≤4.17);且两者均随着水位下...     

煤层群条件下的煤层气成藏特征

基于对我国煤层群发育特征的分析,在概述前人多煤层条件下煤层气成藏特征研究成果的基础上,发现煤层群成藏特征主要表现在垂向上存在“多层统一煤层气系统”或“多层叠置含气系统”, 陆相河流-三角洲-湖泊相的煤层群一般为“多层统一煤层气系统”,海陆过渡相的三角洲-潮坪-泻湖相煤层群一般为“多层叠置含气系统”。进一步解剖比德-三塘盆地实测钻孔资料显示,层序组合是煤层群独立含气系统发育的关键。依据该区抽水钻孔资料分析亦证明,至少存在4套独立含气系统。泻湖潮坪相发育的煤组存在超压的可能,但储层能势分布不均匀。另外,煤层群内部各煤层之间由于“烃浓度封闭效应”及煤层本身的低渗透性对流体流动存在“叠加封闭”作用,使煤层群储层存在“超压”可能性增大。这些结论深化了对煤层群成藏特征的认识。     

群组目标空间方向关系图谱研究

群组目标空间方向关系在地图自动综合、空间分析等领域有着重要的作用。为了定量、直观地表达群组目标之间的空间方向关系,提出一种基于图谱的群组目标空间方向关系计算方法。其基本思路是:首先,构建参考目标群的最小投影矩形MBR(Minimum Bounding Rectangle),并对其以正北方向为起止每隔一定角度进行形态变换,求得每次形态变换后参考目标群与源目标群之间的交集,在此基础上得出相应的谱密度,分析谱特征并绘制出对应图谱。实验表明,该方法较好地顾及了群组目标空间方向关系的各种影响因素,能够以定量的方式精确计算群组目标之间的空间方向关系,并能将其结果进行可视化表达。     

河蟹生态养殖池浮游植物功能类群的结构特征

为探究河蟹生态养殖池浮游植物群落的结构及动态,2013年4-10月对上海松江泖港地区河蟹养殖池的浮游植物进行了调查,分析其种类构成、密度、生物量和生物多样性.共检测到浮游植物105种,其中河蟹生态养殖池优势种11种,分别属于B、D、J、LO、X1、WO、X2、S1和MP功能群.河蟹养殖池浮游植物平均密度为282.58×10~4cells/L,平均生物量为1.59 mg/L,Shannon-Wiener多样性指数变化范围为2.11~3.09.水源浮游植物平均密度为175.13×104cells/L,平均生物量为0.99 mg/L,Shannon-Wiener多样性指数变化范围为1.70~2.79.河蟹养殖池浮游植物平均密度分别于5月14日-6月14日和7月29日-8月29日与水源差异显著;河蟹养殖池浮游植物平均生物量分别于5月30日、6月14日和7月29日-8月29日与水源差异显著;河蟹养殖池浮游植物Shannon-Wiener生物多样性指数分别于5月14日-6月14日和8月14日-9月15日与水源差异显著.河蟹养殖池浮游植物的平均密度、平均生物量和生物多样性指数与水源水体变化趋势基本一致,均高于水源,群落稳定.     

HUDF 1619—A candidate for polar-ring galaxies in the Hubble Ultra Deep Field

A galaxy that is a good candidate for polar-ring galaxies has been detected in the Hubble Ultra Deep Field (HUDF). The galaxy HUDF 1619 (V ≈ 25 ^m , z ～ 1) is the most distant object of this type known to date. A large-scale structure crosses the highly warped disk of the main galaxy seen almost edge-on at an angle of about 70°. The luminosity of this structure (the possible polar ring) reaches ～1/3 of the luminosity of the central galaxy. A strong absorption lane is seen in the region where this structure is projected onto the disk of the central object. There are two galaxies of comparable luminosity adjacent to HUDF 1619 (in projection). One of them may be the donor galaxy the interaction with which gave rise to the ring structure.     

Groups of galaxies. IV. Effect of observational selection on the relationship between the characteristics and distance of groups and a comparison with the groups of Geller and Huchra

The effect of observational selection on the relationship between the characteristics of groups of galaxies and their distances is discussed in this paper. For our groups the dependence of the pairwise distance between the members on the distance of the group is just that. For the groups of Geller and Huchra, on the other hand, the analogous dependence is distorted by the effect of their selection criteria for groups of galaxies. The average dispersion of the radial velocities of the galaxies for our groups is less than half that for the groups of Geller and Huchra, while the mass-to-luminosity ratio is smaller, on the average, by more than an order of magnitude in our case. Geller-Huchra groups with mass-to-luminosity ratios greater than 1000 are most likely unreal. __________ Translated from Astrofizika, Vol. 50, No. 4, pp. 535–546 (November 2007).