格尔木河流域河水钾硼锂元素分布特征及富集规律

在柴达木格尔木河流域,随着内陆流域水系的产生与地表径流的消亡,从山区至盐湖区钾(K)硼(B)锂(Li)等有益元素的分布可以划分为淋溶-径流区、径流-蒸发区与溶滤-蒸发浓缩富集区3个具有显著特点的水文化学分带。河水中,K、B、Li含量随矿化度升高而升高,且呈正相关关系。在盐湖区,K、B、Li等资源性元素明显富集。研究发现,格尔木河东部主流(秀水河)是格尔木河水中B和Li的主要贡献者。     

Length of stay in urban areas of circular migrants from the mountainous areas in China

Currently, there is limited literature dealing with the length of stay of circular migrants in urban areas (LSCMU), although many studies have discussed the phenomenon of migration and the determinants of migration. This study attempts to fill that gap using survey data from the mountainous areas of Chongqing, Southwest China. From a comparative perspective, this study divided workers into two groups (a young group aged between 16 and 35 years and an old group aged between 36 and 65 years). The average LSCMU values for the young and old groups were 225 days and 174 days, respectively. Two multi-regression models were used to estimate the determinants of LSCMU in the two groups. The results showed that LSCMU was closely related to individual factors in both groups, including gender, age and job training. Family and community factors, including household size, arable land per capita and the distance from market, had much weaker effects on the dependent variable, especially in the older group. It was noticeable that job training had significant positive effects on LSCMU in both groups; these findings have special implications for the urbanization process in China.     

矿业权边界在资源储量估算垂直纵投影图上的确定

利用垂直纵投影图进行资源储量估算时,当矿体走向与矿业权边界斜交时,矿业权边界在资源储量垂直纵投影图上投影的准确位置较难确定。该文介绍了利用不同中段平面图和利用计算公式确定矿业权边界在资源储量垂直纵投影图上的投影位置,对解决此类问题具有一定的参考价值。     

Effects of Column Diameter on Setting Behavior of Dredged Slurry in Sedimentation Experiments

This article investigates the influence of dimensions of a settling column on the settling mode and the settling rate. End conditions of the settling stage in the hindered settling were also analyzed. It was found that the settling mode in a column with a smaller diameter tends to be consolidation settling. The effect of a settling column wall decreases with increasing column diameter, and it can be ignored provided the column diameter is larger than 14.5 centimeters. For the difference in initial water content, the settling behavior of the slurry develops a different sensitivity to the diameter effect. The influence of column diameter reduces as the initial water content of the slurry becomes higher. It is suggested that the internal diameter of the column used in a sedimentation experiment should be 14.5 centimeters.     

海洋浮游微食物网结构及其影响因素

微食物环是海洋生态系统中重要的物质和能量过程,是传统食物链的有效补充。微食物环研究是当前海洋生态学研究的热点之一,但对其结构的系统研究较少,海洋微食物网结构在2000年才被Garrison提出。尽管微食物网各个类群的丰度在不同海洋环境中有相对变化,但是这些变化都处于一定的范围之内,其丰度结构约为纤毛虫10 cell ml-1、鞭毛虫103 cell ml-1、微微型真核浮游生物104 cell ml-1、蓝细菌104-5 cell ml-1、异养细菌106 cell ml-1、病毒107 particle ml-1。海洋浮游食物链中捕食者和饵料生物粒径的最佳比值为10:1,实际研究中该比值会略低,例如纤毛虫与其饵料的粒径比值为8:1,鞭毛虫为3:1。Pico和Nano浮游植物的丰度比（Pico:Nano）是研究微食物网结构的指数之一,该指数具有不受研究尺度影响的优点,可用于研究区域性和全球性微食物网结构。近年来,学者们从多角度对海洋微食物网的结构开展了研究,不同海区微食物网各类群丰度、生物量的时间和空间变化研究有很多报道,微食物网的结构可受空间、季节、摄食、营养盐等多种因素影响。在对不同空间微食物网的研究中,学者往往研究不同物理性质的水团中各类群生物丰度的不同,以此来表征微食物网结构的不同;同一海区微食物网结构的季节变化也是使用各个类群丰度和生物量的变化来表示,该变化主要受水文环境因素影响。摄食者对微食物网各类生物的影响通过三种途径：1. 中型浮游动物摄食;2. 中型浮游动物摄食微型浮游动物,通过营养级级联效应影响低营养级生物;3. 中型浮游动物通过释放溶解有机物、营养盐影响细菌和低营养级生物。浮游植物通过产生化感物质和溶解有机物影响微食物网结构,而营养盐的浓度及变化则可以对微食物网产生直接或间接影响。     

Analysis of urbanization based on center-of-gravity movement and characteristics in Songhua River basin of China and its southern source sub-basin between 1990 and 2010

Urbanization in modern times led to a series of development strategies that brought new opportunities in China. Rapid urbanization caused severe stress to the ecosystems and the environment. Using the center-of-gravity(COG) method and parameters such as population, economy, and land, we studied the urbanization pattern in Songhua River Basin and its southern source sub-basin from 1990 to 2010. Urbanization was analyzed based on the COG position, eccentric distance, movement direction of COG, and distance of COG movement. Various characteristics of urbanization in the southern source sub-basin of the Songhua River were explained in relation to the whole Songhua River Basin. Urbanization in the southern source sub-basin of the Songhua River is balanced, relatively advanced, and stable compared to the whole Songhua River Basin. The average eccentric distance between the urbanization COGs in the Songhua River′s south source basin indicated rapid expansion of land urbanization during the span of this study. A basic pattern of urbanization COG in the whole Songhua Basin was observed, but there existed differences among the three aspects of urbanization process. Land urbanization is still in its active stage, so future studies should focus on analysis of such urbanization trends.     

Complete nuclear ribosomal DNA sequence amplification and molecular analyses of <Emphasis Type="Italic">Bangia</Emphasis> (Bangiales,Rhodophyta) from China

Filamentous Bangia, which are distributed extensively throughout the world, have simple and similar morphological characteristics. Scientists can classify these organisms using molecular markers in combination with morphology. We successfully sequenced the complete nuclear ribosomal DNA, approximately 13 kb in length, from a marine Bangia population. We further analyzed the small subunit ribosomal DNA gene (nrSSU) and the internal transcribed spacer (ITS) sequence regions along with nine other marine, and two freshwater Bangia samples from China. Pairwise distances of the nrSSU and 5.8S ribosomal DNA gene sequences show the marine samples grouping together with low divergences (00.003; 0–0.006, respectively) from each other, but high divergences (0.123–0.126; 0.198, respectively) from freshwater samples. An exception is the marine sample collected from Weihai, which shows high divergence from both other marine samples (0.063–0.065; 0.129, respectively) and the freshwater samples (0.097; 0.120, respectively). A maximum likelihood phylogenetic tree based on a combined SSU-ITS dataset with maximum likelihood method shows the samples divided into three clades, with the two marine sample clades containing Bangia spp. from North America, Europe, Asia, and Australia; and one freshwater clade, containing Bangia atropurpurea from North America and China.