Effects of waterlogging and cadmium on ecophysiological responses and metal bio-accumulation in Bermuda grass (<Emphasis Type="Italic">Cynodon dactylon</Emphasis>)     

Shuduan Tan  Fangxu Dong  Yuting Yang  Qingru Zeng  Bin Chen  Lihong Jiang 《Environmental Earth Sciences》2017,76(20):719

Bermuda grass (Cynodon dactylon) can endure long-term and deep submergence stress and cadmium toxicity, respectively. But we do not know whether they can endure cadmium plus waterlogging and what are the differences of ecophysiological responses and metal bio-accumulation of Bermuda grass subjected to normal condition, waterlogging, cadmium or cadmium-and-waterlogging treatments, respectively. Here, the four treatments on Bermuda grass are performed with four replications. Our objective is to determine the ecophysiological responses and endurance abilities, cadmium and zinc bio-concentration and translocation, and the metal uptake mechanisms of Bermuda grass subjected to the four treatments. Our results demonstrated different treatments showed different ecophysiological responses in Bermuda grass. The shoot weights of cadmium treatment were significantly lower than those of the other treatments when the values determined after treated 25 d. Cadmium had a certain promotion effect on the root growth at the early growth stage. SPAD values indicate the relative amounts of chlorophyll present in plant leaves. SPAD value of 35 d was higher than 25 d of cadmium treatment, indicating cadmium had negative effects on chlorophyll contents in the early stage, but the negative effects might be ameliorated as plants adapted to cadmium stress. Waterlogging induced the biomass decrease and accelerated cadmium translocation. The plant leaves had the highest cadmium contents exposed to cadmium-and-waterlogging treatment, while the root showed the highest cadmium contents suffered only cadmium stress. The bio-concentration factor of cadmium-and-waterlogging treatment was less than that of cadmium treatment, but the translocation factor of cadmium-and-waterlogging treatment was much greater than that of cadmium treatment, which indicated phytostabilization was the main phytoremediation process subjected to only cadmium stress, while phytoextraction was the main process when exposed to cadmium-and-waterlogging treatment. Bermuda grass was a cadmium hyperaccumulator and had strong adaptability to waterlogging, cadmium toxicity or both.  相似文献   

Origin of the volcanic rocks erupted in the eastern Manus Basin: Basaltic andesite-andesite-dacite associations     

Yao Ma  Zhigang Zeng  Shuai Chen  Xuebo Yin  Xiaoyuan Wang 《中国海洋大学学报(英文版)》2017,16(3):389-402

There has been much recent interest in the origin of intermediate lava and several hypotheses are: 1) direct melting of the mantle under water-saturated conditions, 2) partial melting of altered crust, 3) fractional crystallization of parent magma, and 4) magma mixing of mafic magmas with dacitic/rhyolitic magmas. Volcanic rocks series ranging from basaltic andesite to dacite (SiO₂ ranges from 53.8 to 63.0 wt.%) from the eastern Manus Basin were detected for major and trace element compositions to understand their origin. Low H₂O contents, positive correlations of La-SiO₂ and Yb-SiO₂, oxygen isotope data and the indistinct change of trace element concentrations in oscillatory zoning of plagioclase phenocrysts rule out the models in which silicic lava results from direct melting of hydrous mantle, partial melting of altered oceanic crust or gabbros, and magma mixing, respectively. Besides, the geochemical data of whole rock and melt inclusions indicate that fractional crystallization plays a dominant role in generating the intermediate lava with subduction features.  相似文献   

《湖北省地图集》制作难点及解决方法探析     

李晶  蒋共和  汪冰  曾真 《国土资源导刊(湖南)》2017,14(2)

以湖北省地图集编制为例,简要介绍了纪录湖北发展状况的大型综合性图集的表示内容,着重探讨了图集中各区域普通地图设计技术难点及新方法的应用,并分析了制作过程中出现的等高线综合、地貌晕渲、影像色调处理等问题及其解决方法。  相似文献   

Expansion strategies and evolution paths of hotel groups in China     

Guojun Zeng 《中国地理科学(英文版)》2010,20(4):372-380

The organizational structure change of enterprises should be subject to the change of strategy, and strategy change is the reaction to the environment change. This paper studied the expansion strategies and evolution paths of hotel groups in China by a survey in 2007, in which the research objects were 91 hotel groups listed by China Tourist Hotels Association. The conclusions are drawn: based on the two dimensions of unification management function scope and the unification management degree, hotel groups can be divided into four strategic types, including strategically concentrated group, close function group, widespread alliance group and loose union group. Simultaneously there are three different expansion paths: stability path, growth path and undulation path. About 72.5% of Chinese hotel groups have a stability or growth expansion path.  相似文献   

Mesoscale structure of the central South China Sea detected by SCSMEX Buoy and Argo float     

曾丽丽  王东晓  杜岩  施平 《中国海洋湖沼学报》2010,28(5):1102-1111

We addressed the mesoscale structure variation of the central South China Sea (SCS) with the measurements by a long-lived Argo float and a high-resolution ATLAS buoy during 1998–2002. T-S diagram indicates cooling and freshening events in 2000 and 2001 with lower salinity (0.5–0.8) and lower temperature (1–1.7°C). Significant decrease in the net heat flux and increase in the precipitation suggest that the cooling and freshening is due to extra forcing by the atmosphere. Additional to large year-to-year changes, intraseasonal variability is moderate in the research area. The axis of the maximum intraseasonal temperature and salinity signals are mainly located on the thermocline. Typically, amplitude and period of intraseasonal temperature is about 2°C and 40–60 days, and that of salinity is 0.3–0.5 and 35–60 days. Rapidly-changing winds, heat flux, and precipitation are critical in controlling the intraseasonal fluctuations of the mixed layer of the area. Studies on heat and freshwater balance in the mixed-layer further suggest that horizontal advection plays an important role in intraseasonal fluctuation in the upper ocean. In addition, the energetic mesoscale propagation radiated from the east boundary is linked to the intraseasonal variability in winter.  相似文献   

234Th-derived particulate organic carbon export flux in the western Arctic Ocean     

余雯  陈立奇  程建平  何建华  尹明端  曾志 《中国海洋湖沼学报》2010,28(6):1146-1151

To evaluate the particle dynamics and estimate the POC (particulate organic carbon) export flux from the euphotic zone in the western Arctic Ocean, ²³⁴Th-²³⁸U disequilibrium was applied during the second Chinese National Arctic Research Expedition (July 15–September 26, 2003). The POC export fluxes are estimated from the measured profiles of the ²³⁴Th/²³⁸U activity ratios and the POC/PTh ratios. The average residence times of the particulate and dissolved ²³⁴Th in the euphotic zone are 33 d and 121 d, and their average export fluxes are 480 dpm/m²d and 760 dpm/m²d, respectively. The scavenging and removal processes of particle reactive elements are active in the upper layer of the Chukchi Sea. The average residence time of ²³⁴Th increases from shelf to basin, while the export fluxes of ²³⁴Th decrease. The estimated POC export fluxes from the euphotic zone vary from 2.1 to 20.3 mmol/m²d, indicating that the western Arctic Ocean is an important carbon sink in summer due to efficient biological pump.  相似文献   

基于不同地形的GPS对流层延迟插值方法研究   总被引：1，自引：1，他引：0  

王勇  焦健  曾琪明  刘严萍 《大地测量与地球动力学》2010,30(3)

通过利用北京、武汉两地的GPS数据,采用反距离加权法、克里金法研究不同地形下GPS对流层延迟插值效果.经比较,反距离加权法与克里金法的插值效果基本一致,在对武汉地区进行GPS对流层延迟插值时插值效果均在毫米级,在北京地区的插值效果则有不同:平坦地区插值效果达到毫米级;山区插值效果为厘米级,无法满足应用需求.  相似文献   

Finite-Difference Modeling and Dispersion Analysis of High-Frequency Love Waves for Near-Surface Applications   总被引：3，自引：0，他引：3  

Yinhe Luo  Jianghai Xia  Yixian Xu  Chong Zeng  Jiangping Liu 《Pure and Applied Geophysics》2010,167(12):1525-1536

Love-wave propagation has been a topic of interest to crustal, earthquake, and engineering seismologists for many years because it is independent of Poisson’s ratio and more sensitive to shear (S)-wave velocity changes and layer thickness changes than are Rayleigh waves. It is well known that Love-wave generation requires the existence of a low S-wave velocity layer in a multilayered earth model. In order to study numerically the propagation of Love waves in a layered earth model and dispersion characteristics for near-surface applications, we simulate high-frequency (>5 Hz) Love waves by the staggered-grid finite-difference (FD) method. The air–earth boundary (the shear stress above the free surface) is treated using the stress-imaging technique. We use a two-layer model to demonstrate the accuracy of the staggered-grid modeling scheme. We also simulate four-layer models including a low-velocity layer (LVL) or a high-velocity layer (HVL) to analyze dispersive energy characteristics for near-surface applications. Results demonstrate that: (1) the staggered-grid FD code and stress-imaging technique are suitable for treating the free-surface boundary conditions for Love-wave modeling, (2) Love-wave inversion should be treated with extra care when a LVL exists because of a lack of LVL information in dispersions aggravating uncertainties in the inversion procedure, and (3) energy of high modes in a low-frequency range is very weak, so that it is difficult to estimate the cutoff frequency accurately, and “mode-crossing” occurs between the second higher and third higher modes when a HVL exists.  相似文献   

2013年吉林前郭M_S5.8震群序列研究     

薛艳  曾宪伟  刘桂萍  蔡宏雷 《中国地震》2015,31(3):481-491

对前郭M_S5.8地震后6个月(2013年10月31日~2014年4月30日)内的地震事件进行了重新定位,并利用吉林区域地震台网提供的地震目录研究了序列活动特征。精定位结果显示,余震区呈NW走向分布,长轴约11km,短轴约6km。震源深度为5~15km。结合区域构造特征认为,该序列可能与NW走向的通榆-长春隐伏断裂活动有关,序列具有b值较低、5级地震频次高、发震时间集中的特点。序列主要起伏活动可以分为3个时段:主震后10天,余震强度衰减不明显;此后的2次起伏活动,地震活动分别表现出平静-增强(震级爬升)-发生强震和增强(震级爬升)-平静-再增强(震级爬升)-发生强震的特点;在序列早期阶段,震级-频度无法拟合成1条直线,G-R关系在低震级段和高震级段呈现2个线性段;在M_S5.8地震前h值有变小的趋势,且接近1;而M_S5.8地震后h值明显增大;M_S5.5地震后15天序列衰减比较慢,p值为0.76;M_S5.8地震后15天序列衰减较快,p值为1.17。  相似文献   

背景场项目中iDirect卫星通信系统设计   总被引：1，自引：1，他引：0  

杨乐  谭颖  章静  曾薇 《地震地磁观测与研究》2015,(2):114-117

介绍背景场项目中i Direct卫星通信系统,主要从背景场项目对卫星通信的需求、系统设计、数据接入、系统应用等方面进行阐述,具体介绍卫星信系统为行业网备份的数据接入方案以及数据应用案例,可独立为国家测震台提供数据传输信道,保障测震速报业务的正常开展。  相似文献