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Peiyue?LiEmail authorView authors OrcID profile Jianhua?Wu Hui?Qian Wanfang?Zhou 《Environmental Earth Sciences》2016,75(10):909
The West Development Program, initiated in 2000 by the central government of China, has attracted huge investments in the arid and semiarid regions of northwest China. As a consequence of this development, environmental pollution and ecological degradation have been widely reported. The Silk Road economic belt proposed by China promotes further economic development in the regions, but rational planning and regular monitoring are essential to minimize any additional negative impacts of the anthropogenic activities. This article reports an investigation on the distribution, enrichment and sources of trace metals in the topsoil in and around the Ningxia Hengli Steel Wire Plant (HSWP) situated along the Silk Road economic belt. The concentrations of Cd, Pb, Cr, Cu, Zn, Ni, Mn, V and Co in the surface soils of the study area vary, respectively, in the following ranges: 0.083–18.600, 21.9–2681.0, 58.0–100.0, 14.6–169.9, 59.0–4207.3, 19.3–40.8, 411–711, 55.2–76.6 and 7.46–25.21 mg/kg. The concentrations of Cd, Pb, Cr, Cu, Zn and Co are significantly higher than their local background values. Pollution levels of these trace metals in the surface soils were assessed using contamination index (C f i ), geo-accumulation index (I geo), modified contamination degree (mC d) and pollution load index. The potential ecological risks caused by the metal pollution were assessed by means of potential ecological risk factor (E f i ) and potential ecological risk index. The Spearman correlation and cluster analysis were applied to determine the contamination sources. The HSWP zone, associated with very high potential ecological risk caused by Pb and Cd, is more seriously contaminated by trace metals than the residential zone. This study indicates that Cd, Pb, Cu, Zn and Co mainly originate from industrial pollution, whereas Cr, Mn, Ni and V result from both industrial activities and natural processes. 相似文献
975.
Grateloupia ramosa Wang & Luan sp. nov. (Halymeniaceae, Rhodophyta) is newly described from Hainan Province, southern China. The organism has the following morphological features: (1) purplish red, cartilaginous and lubricous thalli 5–10 cm in height; (2) compressed percurrent axes bearing abundant branches with opposite arrangement; (3) claw-like apices on top, constricted to 2–4 cm at the base; (4) cortex consisting of 3–6 layers of elliptical or anomalous cells and a medulla covered by compact medullary filaments; (5) reproductive structures distributed throughout the thallus, especially centralized at the bottom of the end portion of the branches; and (6) 4-celled Carpogonial branches and 3-celled auxiliary-cell branches, both of the Grateloupia-type. The morphological diff erences were supported by molecular phylogenetics based on ribulose-1, 5-bisphosphate carboxylase/oxygenase (rbcL) gene sequence analysis. There was only a 1 bp divergence between specimens collected from Wenchang and Lingshui of Hainan province. The new species was embedded in the large Grateloupia clade of the Halymeniaceae. The pairwise distances between G. ramosa and other species within Grateloupia ranged from 26 to 105 bp, within pairwise distances of 13–111 bp between species of the large genus Grateloupia in Halymeniaceae. Thus, we propose this new species as G. ramosa Wang & Luan sp. nov. 相似文献
976.
Previous studies suggest that spring SST anomalies over the northern tropical Atlantic(NTA) affect the tropical cyclone(TC) activity over the western North Pacific(WNP) in the following summer and fall. The present study reveals that the connection between spring NTA SST and following summer–fall WNP TC genesis frequency is not stationary. The influence of spring NTA SST on following summer–fall WNP TC genesis frequency is weak and insignificant before, but strong and significant after, the late 1980 s. Before the late 1980 s, the NTA SST anomaly-induced SST anomalies in the tropical central Pacific are weak, and the response of atmospheric circulation over the WNP is not strong. As a result, the connection between spring NTA SST and following summer–fall WNP TC genesis frequency is insignificant in the former period. In contrast,after the late 1980 s, NTA SST anomalies induce pronounced tropical central Pacific SST anomalies through an Atlantic–Pacific teleconnection. Tropical central Pacific SST anomalies further induce favorable conditions for WNP TC genesis,including vertical motion, mid-level relative humidity, and vertical zonal wind shear. Hence, the connection between NTA SST and WNP TC genesis frequency is significant in the recent period. Further analysis shows that the interdecadal change in the connection between spring NTA SST and following summer–fall WNP TC genesis frequency may be related to the climatological SST change over the NTA region. 相似文献
977.
The lower Cambrian develops a set of organic-rich black shales in Yangtze Platform and is regarded as one of the key layers of shale gas exploration. The microscope pore structure characteristics and methane sorption capacity were investigated using scanning electron microscope, nitrogen adsorption and methane sorption experiments, and then their controlling factors combining with organic matter, mineral compositions were discussed for Niutitang shales in Zunyi area, Mufushan shales in Nanjing area and Huangboling shales in Chizhou area. The results show as below; ( I ) The pores in lower Cambrian shales are mainly dominated by organic pores, interlayer pores in clay minerals and micro-fractures, as well as containing some intergranular pores between brittle mineral grains, honeycomb poies formed by pyrite crystals falling out, and dissolution molds in fossils; ( 2) DKT pore size distributions show the pores is mainly concentrated in the range of less than 4 nm in lower Cambrian shales and kerogens, while a certain amount of pores are above 4 nm are also existed in lower Cambrian shales, which may be contributed by smectite; ( 3)The specific surface area, pore volume and Langmuir methane sorption capacity of the lower Cambrian shales are ranging from 5.58 to 31. 96 inVg, 0.026 to 0.088 mL/g and 1.36 to 5. 3 mL/g, respectively, which are mainly controlled by TOC and smectite contents, but the effect of TOC and smectite on physical properties are quite different for the lower Cambrian shales in different regions; ( 4)The specific surface area of two Niutitang kerogens are 7. 08 and 7. 92 times than that of the shales and methane sorp-Tion capacity of kerogens arc 5.81 and 7.09 times than that of the shales, suggesting that kerogen is a main carrier of methane gas occurrence in. 相似文献
978.
基于CHAMP卫星高精度磁场观测数据,对2001—2009年径向行星际磁场(RIMF, radial interplanetary magnetic fields)条件下的场向电流的分布特征进行了统计学分析, 并与2001—2009年期间场向电流的平均强度进行了对比研究, 结果表明:正午时刻场向电流的平均强度对地偶极子倾角有明显线性依赖, 冬夏季电流强度比值约为3左右, RIMF条件下冬夏季比值降为2;相对年平均值来说, RIMF条件下行星际磁场总幅度、重联电场、太阳风动压均有所减小, AE指数减弱, Dst指数略有降低;在通常情形下重联电场是场向电流很好的控制参数, 但是在RIMF下, 重联电场不再与电流强度相关;北半球电流强度在向地IMF条件下大于向日IMF, 而南半球则相反, 虽然RIMF条件下场向电流的均值小于年平均值, 但是正午时段场向电流强度大于年平均值的概率大约为0.2, RIMF条件下仍然有地磁扰动事件(比如亚暴事件)发生。 相似文献
979.
Xiang Huang Zhizhong Wang Jianhua Guo 《International journal of geographical information science》2016,30(7):1426-1449
This study introduces a transition probability-based Bayesian updating (BU) approach for spatial classification through expert system. Transition probabilities are interpreted as expert opinions for updating the prior marginal probabilities of categorical response variables. The main objective of this paper is to provide a spatial categorical variable prediction method which has a solid theoretical foundation and yields relatively higher classification accuracy compared with conventional ones. The basic idea is to first build a linear Bayesian updating (LBU) model that corresponds to an application of Bayes’ theorem. Since the linear opinion pool is intrinsically suboptimal and underconfident, the beta-transformed Bayesian updating (BBU) model is proposed to overcome this limitation. Another type of BU approach, conditional independent Bayesian updating (CIBU), is derived based on conditional independent experts. It is shown that traditional Markovian-type categorical prediction (MCP) is equivalent to a particular CIBU model with specific parameters. As three variants of the BU method, these techniques are illustrated in synthetic and real-world case studies, comparison results with both the LBU and MCP favor the BBU model. 相似文献
980.