中国新企业成立空间差异的影响因素——以金属制品业为例   总被引：3，自引：1，他引：2  

史进  贺灿飞 《地理研究》2018,37(7):1282-1296

新企业是产业空间重构的重要驱动力。采用1998-2007年中国工业企业数据库,以金属制品业为例,发现金属制品业新企业成立的活跃地区由东部沿海转向中西部地区,特别是中部地区。随后建立“全球链接、区域竞争和地方环境”的分析框架,通过城市层面的面板Tobit模型,考察新企业成立空间差异的影响因素,并突出企业效率在这些因素作用过程中的影响。研究发现：① 外向型城市有利于新企业成立;低效率的新企业只是追求劳动力的低成本,但是高效率的新企业还能兼顾劳动力的高质量。② 区域市场潜力大的城市有利于新企业成立。③ 市场化环境好的城市有利于新企业成立,地方化经济对新企业成立无显著影响,而适度的相关多样化能够促进高效率新企业成立。  相似文献   

A review of Australian salt lakes and associated mineral systems   总被引：1，自引：0，他引：1  

T. P. Mernagh  E. N. Bastrakov  S. Jaireth  P. de Caritat  P. M. English  J. D. A. Clarke 《Australian Journal of Earth Sciences》2016,63(2):131-157

This study reviews the available information for over 1200 Australian salt lakes including in areas that have little or unreliable data. Publicly available groundwater hydrogeochemical datasets for the Australian arid zone are particularly sparse, inconsistent and of variable quality. Many datasets in the vicinity of salt lakes only report salinity or total dissolved solids, with no data for constituent cations and anions, and no appreciation of the hydrological and geomorphic evolution of the lakes. To overcome these limitations and to provide a broad-scale context, we developed mineral systems models to assess the potential of Australian salt lakes for potash, lithium and boron deposits. These models show that an important control on the potential of salt lake systems to form economic deposits of potash, lithium or boron is hydrogeological connectivity between leachable source rocks and the lakes. The assessment of the mineral potential was carried out in two stages. The first stage selection was based on the presence of favourable source rocks in the salt lakes’ catchments. The mean values of concentration in each catchment were derived from whole rock, sediment and groundwater geochemical datasets by averaging the values in samples (separately for each of the three datasets) located in the catchment and assigning this value to the catchment's salt lakes. The second stage selection was carried out by analysing available chemical data of groundwater in proximity to the salt lake systems delineated in the first stage. As a result, six regions were identified as having the highest potential, for potash in particular, but also for lithium and/or boron deposits. These are: the Lake Frome/Central Gawler Region of South Australia; two regions in the Northern Territory: the central western region extending into Western Australia, and the Lake Woods region; and, in Western Australia, the Lake Disappointment region, the north east Yilgarn and south east Yilgarn regions.  相似文献   

水体铜离子吸收系数光谱(400-900 nm)测量     

梁业恒  邓孺孺  高奕康  秦雁  刘旭拢 《遥感学报》2016,20(1):27-34

金属溶解物的吸收光谱测量是水体重金属遥感反演的关键。本文使用水体透射光测量装置,利用ASD光谱仪测量相同厚度不同浓度铜离子溶液的透射光辐亮度,运用比值法计算水体铜离子消光系数和吸收系数,最终得到400—900 nm波长范围内的水体铜离子单位浓度吸收系数光谱。该方法可以较好地消除实验装置和水中悬浮物的影响。结果表明,水体铜离子在蓝、绿光波段吸收作用极小,红光至红外波段的吸收系数快速增大,与铜离子溶液颜色相吻合;吸收峰位于810 nm。多次独立实验测量所得结果的标准差很小,说明测量结果稳定。与Jancsò测量结果的对比分析表明,本文结果与国际上著名测量结果接近,且部分波段的测量值更为合理。  相似文献   

沼生植物过渡金属元素含量季节变化特征——以三江平原典型湿地植物为例   总被引：6，自引：2，他引：4  

王金达  刘景双  于君宝  李仲根 《地理科学》2003,23(2):213-217

三江平原沼泽湿地生态系统不同水文条件下(高、中、低位区),同种植物和不同植物不同器官中过渡金属元素Fe、Mn、Zn、Cu含量季节变化规律基本相似,亦表现出一定的时间分配差异。高、中和低位区小叶章茎、叶、根中Fe含量季节变化规律为幼苗时期最高,成熟后含量减少(高位区根除外);高、中和低位区茎、叶中Mn含量随季节分配趋势是先减少后增加,而根中Mn含量变化较复杂;高、中和低位区茎、叶和根中Zn含量随季节变化呈初期含量高,后期含量低(低位区茎、根除外)的趋势,而中期变化复杂;各区植物茎、叶和根中Cu含量基本呈随时间变化含量逐渐下降,高位区根和低位区的叶含量变化趋势较特殊;从元素含量水平比较,高、中小叶章和低位区毛果苔草表现为茎、叶Mn含量>Fe含量,根中Fe>Mn;茎、叶、根中Zn>Cu。  相似文献   

金属活动态提取技术在十红滩铀矿的应用   总被引：4，自引：1，他引：3  

刘红艳  王学求 《吉林大学学报(地球科学版)》2006,36(2):183-186

通过十红滩铀矿上方土壤中铀的存在形式研究发现,能指示深部隐伏矿信息的铀酰络阳离子富集在地表覆盖物弱胶结层细粒级粘土中,可占全铀比例的17%～40%。提取土壤中吸附与可交换相的铀可以有效指示矿体,在铀矿体上方,存在明显的铀、钼活动态异常。从而证明金属活动态技术可用于寻找隐伏金属矿床。  相似文献   

Aspect control of water movement on hillslopes near the rain–snow transition of the Colorado Front Range          下载免费PDF全文

Eve‐Lyn S. Hinckley  Brian A. Ebel  Rebecca T. Barnes  Robert S. Anderson  Mark W. Williams  Suzanne P. Anderson 《水文研究》2014,28(1):74-85

In the Colorado Front Range, forested catchments near the rain–snow transition are likely to experience changes in snowmelt delivery and subsurface water transport with climate warming and associated shifts in precipitation patterns. Snowpack dynamics are strongly affected by aspect: Lodgepole pine forested north‐facing slopes develop a seasonal snowpack, whereas Ponderosa pine‐dotted south‐facing slopes experience intermittent snow accumulation throughout winter and spring. We tested the degree to which these contrasting water input patterns cause different near‐surface hydrologic response on north‐facing and south‐facing hillslopes during the snowmelt period. During spring snowmelt, we applied lithium bromide (LiBr) tracer to instrumented plots along a north–south catchment transect. Bromide broke through immediately at 10‐ and 30‐cm depths on the north‐facing slope and was transported out of soil waters within 40 days. On the south‐facing slope, Br^? was transported to significant depths only during spring storms and remained above the detection limit throughout the study. Modelling of unsaturated zone hydrologic response using Hydrus‐1D corroborated these aspect‐driven differences in subsurface transport. Our multiple lines of evidence suggest that north‐facing slopes are dominated by connected flow through the soil matrix, whereas south‐facing slope soils experience brief periods of rapid vertical transport following snowmelt events and are drier overall than north‐facing slopes. These differences in hydrologic response were largely a function of energy‐driven differences in water supply, emphasizing the importance of aspect and climate forcing when considering contributions of water and solutes to streamflow in catchments near the snow line. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

成都平原农田区土壤重金属元素环境基准值初步研究   总被引：5，自引：0，他引：5  

王莹  侯青叶  杨忠芳  杨晓燕  金立新  李忠惠 《现代地质》2012,26(5):953-962

土壤重金属污染已成为制约人类社会发展及危害人类健康的重要因素,制定土壤重金属元素的环境基准值对控制土壤重金属污染及保护生态安全具有重要意义。以成都平原农田区为例,以保护地下水安全为目的,以室内模拟淋溶实验为手段,尝试性地计算了研究区不同类型土壤重金属元素的环境基准值。研究结果表明:(1)不同类型土壤各元素在土壤—水间的分配系数差异较大;(2)不同类型土壤Hg和Cd环境基准值差异不大,Hg环境基准值平均为0.3μg/g,Cd的变化范围为0.3～0.5μg/g;As和Pb环境基准值差异较大,As的变化范围为18～24μg/g;Pb的变化范围为24～41μg/g;(3)研究区土壤基本处于保护饮用水的安全范围之内,但黄壤中Pb、紫色土中Cd和Pb、棕壤中Hg和Pb具有潜在的影响地下水安全的生态风险。这对研究区进行风险评估具有重要的参考价值。  相似文献   

成矿金属元素的溶解性分析和测试技术发展   总被引：1，自引：0，他引：1  

汤化伟  李珍 《地质科技情报》2012,31(1):137-142

成矿过程中金属元素的溶解性是地球化学研究的一个重要领域.探索开放、非平衡状态下地质流体中金属元素的溶解性有助于了解矿床成因和成矿机制.成矿体系的温度、压力和成矿流体的盐度、pH值、fH2O、fHCl及络合物配体(F-、Cl-、S2-等)的浓度等均对成矿金属元素的溶解性有着重要影响.对于成矿体系状态、近年来国内外关于成矿金属元素溶解性的研究及人工合成流体包裹体、傅里叶红外光谱、显微激光拉曼光谱、电感耦合等离子体质谱法、扩展X射线吸收精细结构和紫外-可见光谱技术在金属元素溶解性方面的应用进行了阐述;认为热液金刚石压腔与拉曼光谱仪联合进行的高温谱学技术可以为实现成矿模拟实验和进行谱学原位测量进而解决成矿流体中金属元素的溶解性问题提供一条新思路,具有广阔的前景.  相似文献   

Characteristics of heavy metal accumulation on fly ash- and sewage sludge-amended calcific soil     

Huapeng Niu  Shengrong Li  Junfeng Shen  Meijuan Yao 《中国地球化学学报》2012,31(2):181-186

Land disposal of fly ash(FA)and sewage sludge(SS)is a major problem due largely to their potentially harmful constituents.In this paper,a potting experiment was performed to evaluate the effects on the plant growth and to discuss in particular the potential hazard to soils and plants according to the characteristics of heavy metal accumulation and migration when FA and SS are used as the amendments of calcific soil in a limestone mining area. The results showed that the application of FA-SS mixture is capable of accelerating the growth of plants and improving the biomass production at either 1:1 or 1:2 FA-SS mixture:soil(w/w).The highest yields were obtained at 1:1(w/w)mixing ratio.When compared with the Element Background Values of Soils in China,the analysis on heavy metals indicated that the contents of Pb,Cr,Hg,Cd,As,Ni,Cu and Zn in the amended soils came up to the second-class environmental quality standards,only Hg and Cd showed significant accumulation.At the same time, though the metal concentrations in roots were higher than those for the control,the concentrations except Cu,Zn in shoots were lower.And all the heavy metal contents in the plants were substantially lower than the toxicity limits. The results indicated that the combined use of FA and SS at a rational rate of application should pose no danger to both soil and food chain based on the characteristics of the FS and SS,heavy metals and calcific soil.  相似文献   

三峡库区云阳消落带土壤重金属形态及其在植物中的富集和转移   总被引：5，自引：3，他引：2  

谌金吾  孙一铭  杨占南  张显强  孙敏 《中国岩溶》2012,31(4):415-422

三峡大坝建成蓄水以来,其夏涨秋消的调度方式使得每年5-10月份在海拔145～175 m范围内形成291.1 km2的消落带.本文通过分析云阳消落带土壤重金属含量及其形态和重金属在消落带植物体根、茎、叶的分布,以及植物对重金属的生物富集和转移系数,来研究消落带重金属污染情况及重金属在土壤-植被的富集和转移规律.研究结果表明,云阳消落带存在较为严重的Cd污染,单因子污染指数为5.02,内梅罗综合污染指数为3.637;Cd和Cr主要是生物毒性不强残渣态;Cu形态主要是金属可交换态和碳酸盐结合态,生物毒性比较强;Mn的形态主要是铁锰结合态;Pb的形态分配比例均匀,生物毒性较弱.可交换态与转移系数极显著正相关,相关系数为0.981;有机及硫化物结合态与富集系数显著正相关,相关系数为0.905;铁锰结合态、碳酸盐结合态和残渣晶格结合态对富集和转移系数贡献都不大.三峡库区消落带重金属在植物体内的富集、转移主要由土壤中重金属可交换态和有机及硫化物结合态的性质决定.  相似文献