山东半岛南北两侧海域真核浮游生物群落特征及与环境因子的相关性分析   总被引：1，自引：0，他引：1  

刘朋超  王卫军  骆启豪  李彬  孙国华  赵强  张金浩  杨建敏 《海洋与湖沼》2019,50(4):876-885

为了解山东半岛南北两侧的烟台崆峒岛(KTD)海域和日照东港(DG)海域真核浮游生物群落特征,采用高通量测序技术,以18S rDNA V4区为目标基因,对2017年10月至2018年7月两海域的真核浮游生物多样性进行了检测;同期测定两海域的环境因子(溶解氧、氨氮含量等10个理化指标),并与真核浮游生物丰富度做相关性分析。实验结果表明:通过高通量测序技术共鉴定出浮游生物455种,其中,KTD海域共检测出真核浮游生物36个门类424种;DG海域共检测出真核浮游生物34个门类365种。绿藻门(Chlorophyta)、硅藻门(Diatomea)是两海域浮游植物中整体丰度最高的门类。KTD海域,绿藻门各月丰度在3.0%—21.3%之间,其中2018年7月(K1807)最高,达到了21.3%;硅藻门各月丰度在2.0%—16.59%之间,其中2018年2月(K1802)最高,达到了16.59%。DG海域,绿藻门各月丰度在2.0%—12.3%之间,其中2017年11月份(D1711)最高,达到了12.3%;硅藻门各月丰度在2.0%—47.0%之间,其中1月(D1801)最高,达到了47.0%。占优势地位的浮游动物主要是节肢动物门类的物种,其每月丰度分别在6.0%—38.9%和7.6%—48.6%之间。环境因子相关性分析表明水温、DO、pH、硅酸盐、硝酸盐氮等环境因子为影响该海域浮游生物群落结构的主要因子。研究结果对了解双壳经济贝类养殖区饵料组成及其在时空的变化,对海岸带食物网、生态基础管理和海洋经济贝类养殖生产等方面提供数据支撑。  相似文献   

Implementation of Solute Transport in the Vadose Zone into the “HYDRUS Package for MODFLOW”     

Sahila Beegum  Jiří Šimůnek  Adam Szymkiewicz  K. P. Sudheer  Indumathi M. Nambi 《Ground water》2019,57(3):392-408

The “HYDRUS package for MODFLOW” is an existing MODFLOW package that allows MODFLOW to simultaneously evaluate transient water flow in both unsaturated and saturated zones. The package is based on incorporating parts of the HYDRUS-1D model (to simulate unsaturated water flow in the vadose zone) into MODFLOW (to simulate saturated groundwater flow). The coupled model is effective in addressing spatially variable saturated-unsaturated hydrological processes at the regional scale. However, one of the major limitations of this coupled model is that it does not have the capability to simulate solute transport along with water flow and therefore, the model cannot be employed for evaluating groundwater contamination. In this work, a modified unsaturated flow and transport package (modified HYDRUS package for MODFLOW and MT3DMS) has been developed and linked to the three-dimensional (3D) groundwater flow model MODFLOW and the 3D groundwater solute transport model MT3DMS. The new package can simulate, in addition to water flow in the vadose zone, also solute transport involving many biogeochemical processes and reactions, including first-order degradation, volatilization, linear or nonlinear sorption, one-site kinetic sorption, two-site sorption, and two-kinetic sites sorption. Due to complex interactions at the groundwater table, certain modifications of the pressure head (compared to the original coupling) and solute concentration profiles were incorporated into the modified HYDRUS package. The performance of the newly developed model is evaluated using HYDRUS (2D/3D), and the results indicate that the new model is effective in simulating the movement of water and contaminants in the saturated-unsaturated flow domains.  相似文献   

压裂微震数据初至拾取的时频谱熵法     

田雅男  王环宇  王鑫  黄佳俊  章强 《吉林大学学报(地球科学版)》2020,50(4):1219-1227

在油气田开发过程中，微震监测是获得水力压裂引起裂缝分布的一种较为有效的方法。微震的定位成像与裂缝解释需要利用有效微震信号位置，而微震信号具有低信噪比的特点，传统信号拾取方法无法有效实现较低信噪比条件下初至时刻的准确拾取。本文提出一种基于时频谱熵的初至拾取新方法，该方法首先通过S变换获取含噪信号的时频谱；然后对谱内各个采样点沿频率方向进行分帧操作，并计算每帧频段内的近似负熵值，以最小近似负熵值作为该谱点的负熵值；最后沿时间方向比较各谱点的负熵值，最小值对应的时刻即为初至时刻。本文利用不同信噪比的合成地震数据对该方法进行效果验证，并与长短时窗能量比（STA/LTA）法进行拾取结果对比，结果表明：信噪比在-5 dB时，两种方法拾取效果都很好；信噪比在-10 dB时，时频谱熵法拾取效果更好。时频谱熵法更适合低信噪比情况下的信号初至拾取。  相似文献   

汶川地震同震滑坡物质在震区的滞留和运移及其对龙门山地形演化的影响   总被引：1，自引：1，他引：0       下载免费PDF全文

王伟  刘静  Vincent Godard  张金玉  许冲  李志刚  徐心悦  许强  王鹏  谢克家 《地球物理学报》2018,61(5):1970-1983

2008年M_W7.9汶川地震导致龙门山断裂发生强烈地壳变形，同时引发的巨量同震滑坡加速了该地区的地表剥蚀和河流侵蚀.然而，目前尚缺少系统的数据定量研究滑坡物质的运移以及河流侵蚀速率随时间的演化规律，这些对理解龙门山前缘物质的再分配以及强震对活动造山带地形塑造的作用至关重要.为此，本研究在汶川地震后的6年间，对震区沱江上游3条支流湔江、石亭江、绵远河流域进行了多期次的定点现代河沙采样.通过系统测量河沙中的石英¹⁰Be浓度，并与震前已发表的数据进行对比，发现如下基本特点：（1）震后河沙¹⁰Be浓度均有明显降低，表明同震滑坡物质对河沙的稀释作用；（2）震后河流对河沙的运移量增加为震前的1.3~18.5倍，因此震后龙门山地区侵蚀速率短期显著增加；（3）初步估计得到汶川地震产生的滑坡物质被完全运移出造山带所需要的时间至少为100~4000年，接近龙门山地区强震复发周期；（4）震间和同震产生的构造变形和地表剥蚀在空间上具有互补性.考虑到地表剥蚀引起的地壳均衡反弹效应，认为类似汶川地震的强震有利于龙门山的隆升.认识震前、震时和震后的地壳变形及侵蚀过程有助于更好地理解单次强震事件对高原边界龙门山地形演化的作用.  相似文献   

基于不同地面特性的混凝土框架结构的抗震性能评估          下载免费PDF全文

张丹丽  谢强 《地震工程学报》2018,40(6):1259-1265

基于3层普通抗震混凝土框架结构,采用能力谱法评估了矩形框架结构的抗震性能,从实验结果中获取能力曲线,并利用在地面特性条件下的各站记录的地震地面运动建立需求曲线。评估结果表明,3层混凝土框架可以抵抗地面条件为1和2的所有地震带A,B,C,D和E的地震荷载;对于地面条件3,混凝土框架在地震带A,B,C和D中的实验结果令人满意;对于地面条件4,混凝土框架只对地震带A和B有效。  相似文献   

Photometric Follow-up Transit (Primary Eclipse) Observations of WASP-43 b and TrES-3b and A Study on Their Transit Timing Variations     

Sun Zhao  Ji Jiang-hui  Dong Yao 《Chinese Astronomy and Astrophysics》2018,42(1):101-128

Two photometric follow-up transit (primary eclipse) observations on WASP-43 b and four observations on TrES-3 b are performed using the Xuyi Near-Earth Object Survey Telescope. After differential photometry and light curve analysis, the physical parameters of the two systems are obtained and are in good match with the literature. Combining with transit data from a lot of literature, the residuals (O ? C) of transit observations of both systems are fitted with the linear and quadratic functions. With the linear fitting, the periods and transit timing variations (TTVs) of the planets are obtained, and no obvious periodic TTV signal is found in both systems after an analysis. The maximum mass of a perturbing planet located at the 1:2 mean motion resonance (MMR) for WASP-43 b and TrES-3 b is estimated to be 1.826 and 1.504 Earth mass, respectively. By quadratic fitting, it is confirmed that WASP-43 b may have a long-term TTV which means an orbital decay. The decay rate is shown to be P? = (?0.005248 ± 0.001714) s·yr^?1, and compared with the previous results. Based on this, the lower limit of the stellar tidal quality parameter of WASP-43 is calculated to be ${Q^{\prime }}_{*}\ge 1.5\times {10}^5$, and the remaining lifetimes of the planets are presented for the different ${Q^{\prime }}_{*}$ values of the two systems, correspondingly.  相似文献   

An algorithm to resolve γ-rays from charged cosmic rays with DAMPE     

Zun-Lei Xu  Kai-Kai Duan  Zhao-Qiang Shen  Shi-Jun Lei  Tie-Kuang Dong  Fabio Gargano  Simone Garrappa  Dong-Ya Guo  Wei Jiang  Xiang Li  Yun-Feng Liang  Mario Nicola Mazziotta  Maria Fernanda Munoz Salinas  Meng Su  Valerio Vagelli  Qiang Yuan  Chuan Yue  Jing-Jing Zang  Ya-Peng Zhang  Yun-Long Zhang  Stephan Zimmer 《天文和天体物理学研究(英文版)》2018,(3)

The DArk Matter Particle Explorer(DAMPE),also known as Wukong in China,which was launched on 2015 December 17,is a new high energy cosmic ray and γ-ray satellite-borne observatory.One of the main scientific goals of DAMPE is to observe Ge V-Te V high energy γ-rays with accurate energy,angular and time resolution,to indirectly search for dark matter particles and for the study of high energy astrophysics. Due to the comparatively higher fluxes of charged cosmic rays with respect to γ-rays,it is challenging to identify γ-rays with sufficiently high efficiency,minimizing the amount of charged cosmic ray contamination. In this work we present a method to identify γ-rays in DAMPE data based on Monte Carlo simulations,using the powerful electromagnetic/hadronic shower discrimination provided by the calorimeter and the veto detection of charged particles provided by the plastic scintillation detector. Monte Carlo simulations show that after this selection the number of electrons and protons that contaminate the selected γ-ray events at～10 Ge V amounts to less than 1% of the selected sample.Finally,we use flight data to verify the effectiveness of the method by highlighting known γ-ray sources in the sky and by reconstructing preliminary light curves of the Geminga pulsar.  相似文献   

基于ROMS和4DVAR的沿轨与网格化SSH数据同化效果评价   总被引：1，自引：1，他引：0  

周超杰  丁效华  张杰  杨俊刚  马强 《海洋学报(英文版)》2018,37(9):50-58

Remote sensing products are significant in the data assimilation of an ocean model. Considering the resolution and space coverage of different remote sensing data, two types of sea surface height(SSH) product are employed in the assimilation, including the gridded products from AVISO and the original along-track observations used in the generation. To explore their impact on the assimilation results, an experiment focus on the South China Sea(SCS) is conducted based on the Regional Ocean Modeling System(ROMS) and the four-dimensional variational data assimilation(4 DVAR) technology. The comparison with EN4 data set and Argo profile indicates that, the along-track SSH assimilation result presents to be more accurate than the gridded SSH assimilation, because some noises may have been introduced in the merging process. Moreover, the mesoscale eddy detection capability of the assimilation results is analyzed by a vector geometry–based algorithm. It is verified that, the assimilation of the gridded SSH shows superiority in describing the eddy's characteristics, since the complete structure of the ocean surface has been reconstructed by the original data merging.  相似文献   

Analytic wave series solution of out-of-plane(SH) waves diffraction by an almost semi-circular shallow cylindrical hill          下载免费PDF全文

Chunyang Ji  Vincent Lee 《地震科学（英文版）》2018,31(3):154-165

A closed-form wave equation analytic solution of two-dimensional scattering and diffraction of outof-plane(SH) waves by an almost semi-circular shallow cylindrical hill on a flat, elastic and homogeneous half space is proposed by applying the discrete Fourier series expansions of sine and cosine functions. The semi-circular hill problem is discussed as a special case for the new formulated equation.Compared with the previous semi-circular cases solutions, the present method can give surface displacement amplitudes which agrees well with previous results. Although the proposed equation can only solve the problem of SH-waves diffracted by almost semi-circular shallow hills, the stress and displacement residual amplitudes are numerical insignificantly everywhere. Moreover, the influences of the depth-towidth ratio(a parameter defined in this paper to evaluate the shallowness of the topography of hills) on ground motions are presented and summarized. The limitations and errors of truncation from Graf's addition theorem and Fourier series equations in the present paper are also discussed.  相似文献   

The NE Directed Seismicity Belt in Tibet after the MS8.1 Nepal Earthquake and Its Predictive Significance     

Wang Shuangxu  Zhu Liangyu  Xu Jing  Ji Lingyun  Jiang Fengyun 《中国地震研究》2018,32(1):119-129

After the 2015 M_S8.1 Nepal earthquake, a strong and moderate seismicity belt has formed in Tibet gradually spreading along the northeast direction. In this paper, we attempt to summarize the features and investigate the primary mechanism of this behavior of seismic activity, using a 2-D finite element numerical model with tectonic dynamic settings and GPS horizontal displacements as the constraints. In addition, compared with the NE-trending seismicity belt triggered by the 1996 Xiatongmoin earthquake, we discuss the future earthquake hazard in and around Tibet. Our results show that:the NE-directed seismicity belt is the response of enhanced loading on the anisotropic Qinghai-Tibetan plateau from the Indian plate and earthquake thrusting. Also, this possibly implies that a forthcoming strong earthquake may fill in the gaps in the NE-directed seismicity belt or enhance the seismic hazard in the eastern (the north-south seismic zone) and western (Tianshan tectonic region) parts near the NE-directed belt.  相似文献