Heavy metal distribution and accumulation in the <Emphasis Type="Italic">Spartina alterniflora</Emphasis> from the Andong tidal flat,Hangzhou Bay,China     

Hong-Jiao Pang  Shuang-Shuang Lyu  Xue-Gang Chen  Ai-Min Jin  Pei-Sun Loh  Fei Li  Yan Jiang  Xian-Hui Yang  Kang-Kang Yan  Zhang-Hua Lou 《Environmental Earth Sciences》2017,76(17):627

In order to study the heavy metal accumulation and distribution in the roots, stems, and leaves of Spartina alterniflora, we collected S. alterniflora samples and the associated sediments along three transects at the Andong tidal flat, Hangzhou Bay. Co, Ni, Cd, Pb, Cu, and Zn were mainly accumulated in the aerial parts (stems and leaves) of the plants, and their distributions depended on their mobility and their roles during the metabolism processes of S. alterniflora. The concentrations of Cu, Zn, Cd, Hg, and Pb were significantly enhanced with the increasing of heavy metal concentrations in the sediments, while those of Co and Ni remained relatively constant. Bioaccumulation factors results showed that the serious heavy metal contamination in the sediments from the transect A may overwhelm the accumulation capability of the plants. In addition, the physicochemical properties of the sediments and the pore water therein also play a role in the heavy metal concentrations and accumulations in the plants, because they can influence the behaviors and bioavailabilities of heavy metals during nutrition and bioaccumulation processes of the plants. The sediments with vegetation did not show significantly decreased heavy metal concentration with respect to the unvegetated sediments, although the plants did absorb heavy metals from the sediments. Principal component analysis and correlation analyses indicated that Co–Ni, Cu–Cd–Hg behaved coherently during accumulation, which may be ascribed to their similar accumulation mechanisms. This work provided essential information on the heavy metal accumulation by plants in a tidal flat, which will be useful for the environmental control through phytoremediation at estuaries.  相似文献   

汉江上游郧县庹家湾剖面光释光测年及意义     

张文桐  庞奖励  黄春长  周亚利  查小春  崔天宇  王海燕  杨丹 《中国沙漠》2017,37(5):885-892

在野外考察基础上选择湖北郧县庹家湾剖面为研究对象。在对磁化率和粒度进行分析的同时,用单片再生剂量法进行了光释光测年（OSL）地层断代。OSL测年数据显示：剖面样品年龄处在55.11~13.57 ka BP,且与地层深度呈现出良好的对应关系,此剖面为黄土风化堆积形成。黏粒含量、黏粒/粉砂值以及磁化率值等气候替代性指标数值在马兰黄土层228~260 cm和294~370 cm深度明显高于典型马兰黄土（L₁）,具有明显的成壤特征,通过OSL测年数据判断时间为27.26~21.59 ka BP,说明在晚更新世时期气候并非持续稳定的寒冷干旱,而是具有一定的波动,在此期间气候相对温暖湿润,而且此次气候事件在黄土高原地区其他沉积记录中也有良好记录。  相似文献   

Structure analyses of the explosive extratropical cyclone: A case study over the Northwestern Pacific in March 2007     

Shuai Wang  Gang Fu  Huaji Pang 《中国海洋大学学报(英文版)》2017,16(6):933-944

The synoptic situation and mesoscale structure of an explosive extratropical cyclone over the Northwestern Pacific in March 2007 are investigated through weather station observations and data reanalysis. The cyclone is located beneath the poleward side of the exit of a 200 hPa jet, which is a strong divergent region aloft. At mid-level, the cyclone lies on the downstream side of a well-developed trough, where a strong ascending motion frequently occurs. Cross-section analyses with weather station data show that the cyclone has a warm and moist core. A ‘nose' of the cold front, which is characterized by a low-level protruding structure in the equivalent potential temperature field, forms when the cyclone moves offshore. This ‘nose' structure is hypothesized to have been caused by the heating effect of the Kuroshio Current. Two low-level jet streams are also identified on the western and eastern sides of the cold front. The western jet conveys cold and dry air at 800–900 hPa. The wind in the northern part is northeasterly, and the wind in the southern part is northwesterly. By contrast, the eastern jet carries warm and moist air into the cyclone system, ascending northward from 900 hPa to 600–700 hPa. The southern part is dominated by the southerly wind, and the wind in the northern part is southwesterly. The eastern and western jets significantly increase the air temperature and moisture contrast in the vicinity of the cold front. This increase could play an important role in improving the rapid cyclogenesis process.  相似文献   

由物权法草案论我国土地登记制度的发展          下载免费PDF全文

冯秀峰  戚军  常忠联  逄先跃 《山东国土资源》2007,23(2):35-37

《物权法》是调整财产关系的重要法律,在中国特色社会主义法律体系中起着支架作用。《物权法》中所指的物包括不动产和动产,物权是指权利人直接支配特定的物的权利,其中物权的核心是不动产,不动产里面的核心是土地,因此《物权法》的制定和颁布将对我国的土地登记制度产生直接的影响。我国《物权法(草案)》(以下简称草案)第二章第一节专门对不动产登记做了规定,为了实现我国现行的土地登记制度和即将颁布的草案的有关规定进行有效衔接,探索符合我国国情的土地登记制度,本文结合对草案中相关条款的分析,对今后土地登记制度的发展进行了论述。1…  相似文献   

Finite element analysis of an all-steel buckling-restrained brace     

Jiang Tao  Dai Junwu  Yang Yongqiang  Bai Wen  Pang Hui  Liu Rongheng 《地震工程与工程振动(英文版)》2022,21(4):1119-1135

Typical all-steel buckling-restrained braces(BRBs) usually exhibit obvious local buckling, which is attributed to the lack of longitudinal restraint to the rectangle core plate. To address this issue, all-steel BRBs are proposed, in which two T-shaped steel plates are adopted as the minor restraint elements to restrain the core plate instead of infilled concrete or mortar. In order to investigate the factors that characterize the hysterical responses of this device, different finite element(FE)m...  相似文献   

鄂尔多斯盆地上古生界标志层特征及形成机制     

赵欣  庞军刚  赵琳雁 《江苏地质》2024,48(1):49-58

根据大量的钻探、测井、露头数据,对鄂尔多斯盆地上古生界标志层的岩电特征、层序地层意义及形成的沉积环境进行研究。结果表明：研究区主要发育灰岩、砂岩、泥岩及煤层标志层,依据层序界面的特点将研究区上古生界划分为5个二级层序、12个三级层序,其中SQ1—SQ5属于海相地层层序,SQ6—SQ12为陆相层序。鄂尔多斯盆地上古生界总体上经历了海相—海陆过渡相—陆相的沉积演化过程,标志层受沉积相横向变化的影响,主要形成于三角洲、辫状河三角洲、河流、湖泊、障壁海岸以及浅海陆棚沉积体系。在划分地层及地层对比过程中,可通过控制标志层、对比相邻井、参考厚度变化等,合理、准确地划分地层。  相似文献   

平原河网区降雨径流污染负荷测算——以太湖流域望虞河西岸为例   总被引：1，自引：0，他引：1  

庞琰瑾  袁增伟 《湖泊科学》2021,33(2):439-448

如何精细量化降雨径流污染负荷是流域尺度实现面源精准治污全过程控制的重要前提.本研究以水污染较为严重的望虞河西岸综合示范区为例,通过开展不同土地利用类型的降雨观测实验,修正SCS-CN模型中的初损率,并基于土地利用类型遥感解译和降雨径流污染物浓度测定,精细刻画降雨径流中总磷(TP)、总氮(TN)、氨氮(NH3-N)、化学...  相似文献