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621.
In 2000, 63 (polished) white rice samples were collected in eight administrative areas all over South Korea and analyzed for
16 elements by inductively coupled plasma atomic emission spectrometry (ICP-AES). Potassium had the highest content, next
to Mg, Ca, Si, Zn, Na, Al and Fe. Most of the samples contained worldwide average concentrations of essential and trace elements
in rice grains reported by various researches. For inter-area differences in those elements in the rice, the statistical analysis
showed no significant differences (p > 0.05) among the eight administrative areas, suggesting that inter-area differences were not substantial in most cases.
Thus, the present data can be used as national background levels of elements in rice produced in South Korea. Using the published
data on daily consumption of rice in South Korea, it was possible to estimate the daily intake of As, Cd, Cu, Pb and Zn via
rice. The results showed that a regular consumption of rice produced in Korea plays an important role in accumulation of essential
and trace elements in Korean, especially for farm-households consuming relatively large amounts of rice. 相似文献
622.
Tatjana Bakran-Petricioli Oleg Antonić Dragan Bukovec Donat Petricioli Ivica Janeković Josip Križan Vladimir Kušan Sandro Dujmović 《Ecological modelling》2006
Within the framework of the 3-year project “Mapping the habitats of the Republic of Croatia” the marine benthic habitats of the entire Croatian maritory were mapped. The supralittoral and the mediolittoral were mapped as a function of the coastal lithology and the presumed levels of human impact (both in scale of 1:100,000). The infralittoral was mapped on the basis of spatial modelling (using neural networks as a modelling tool, data about habitats collected by fieldwork as the independent variable for training and testing the model, and the digital bathymetrical model, the distance from coast, the second spectral channel of Landsat ETM+ satellite image and the sea bottom sea temperature, salinity and current magnitude, as dependent variables). The circalittoral and the bathyal were mapped by overlapping and reinterpretation of the existing spatial databases (bathymetry and lithology) within the framework of the raster-GIS. 相似文献
623.
本文调查了我国34个省(区)、市的40种主要土类中Bi的含量,首次提出了我国Bi的土壤环境背景值,并对主要土类及区域分布特征进行了研究,初步分析了影响Bi分布的主要因素. 相似文献
624.
为准确认定电气火灾事故中的过电流故障,模拟在不同电流条件下ZR-BV单芯铜线的过电流故障,通过逐帧分析高速影像研究导线发生过电流故障时的变化过程,使用金相分析技术分类研究过电流导线电弧熔化痕迹的组织特征。结果表明:当I≥4Ie时,导线发生熔断,断路电弧将引燃热分解后的绝缘热解气体,造成火灾的蔓延扩大;过电流导线电弧熔断痕与火烧熔痕的宏观特征较为相似,但喷溅熔痕和发散状熔痕是过电流导线所特有的;枝晶偏析组织是过电流电弧熔断痕的典型组织,且随着电流值的升高,枝晶偏析组织分布范围明显扩大,几乎不再出现等轴状组织。 相似文献
625.
本文在德阳市环境天然放射性水平调查基础上,对市辖5953.75平方公里范围内的五种不同材料路面,47个测点的道路γ辐射剂量率进行了分析研究,其结果是:(1)陆地γ辐射剂量率为5.54×10~(-8)Gyh~(-1);(2)贯空辐射剂量率为8.71×10~(-8)Gyh~(-1);(3)不同材料路面γ辐射剂量率的大小顺序是:泥土>碎石>水泥>柏油>石块路面。 相似文献
626.
John A. Colman Richard F. Sanzolone 《Journal of the American Water Resources Association》1992,28(5):933-950
ABSTRACT: Geochemistry of fine-fraction streambed sediments collected from the upper illinois River basin was surveyed in the fall of 1987 as part of the U.S. Geological Survey National Water-Quality Assessment pilot projects. The survey included 567 samples analyzed for 46 elements. Three distinctive distribution patterns were found for seven U.S. Environmental Protection Agency priority pollutants surveyed, as well as for boron and phosphorus: (1) enrichment of elements in the Chicago urban area and in streams draining the urban area relative to rural areas, (2) enrichment in main stems relative to tributaries, and (3) enrichment in low-order streams at high-population-density sites relative to low-population-density sites. Significant differences in background concentrations, as measured by samples from low-order streams, were observed among five subbasins in the study area. Uncertain geochemical correspondence between low-order, background sites and high-order, generally metal enriched sites prevented determination of background levels that would be appropriate for high-order sites. The within-sample ratio of enriched elements was variable within the Chicago area but was constant in the Illinois River downstream from Chicago. Element ratios imply a composite fine-fraction sediment in the Illinois River of 35–40 percent Des Plaines River origin and 60–65 percent Kankakee River origin. 相似文献
627.
628.
高铁酸钠电化学合成条件的研究 总被引:6,自引:0,他引:6
利用含铁材料为阳极,铜为阴极,NaOH溶液为电解液,于隔膜电解槽中电解制备高铁酸钠。探索了该工艺所必需的各种参数和反应条件,确定了隔膜材料,并对Na2FeO4浓度和电流效率的非一致性变化作出了解释。研究结果表明:在阳极距离为1.3cm(极距2.3cm)、阳极电解液浓度为14mol/L,阴极电解液浓度为4mol/L、温度为35℃、电压为8~9V时,电解2h后得到的Na2FeO4浓度为18.7g/L,电流效率为20%。 相似文献
629.
广州市菜园土主要蔬菜重金属背景含量的研究 总被引:21,自引:2,他引:21
研究了广州市几个主要的蔬菜生产基地种植的白菜、芥蓝、芥菜、菜薹、萝卜、大白菜、豆瓣菜、结球甘蓝、芹菜、菜豆、豌豆、结球莴苣、尖叶莴苣、菠菜、番茄等15种蔬菜中Pb、Hg、Cd、Cr和As等5种重金属的背景质量分数。其背景质量分数为:Pb 0.002~0.148mg/kg;Hg ND-0.006mg/kg;Cd 0.001~0.034mg/kg;Cr 0.002~0.150mg/kg;As 0.001~0.070mg/kg。由于不同种类蔬菜的吸收特性和遗传特性有所不同,其重金属背景质量分数也有很大差异。蔬菜中元素水平还与土壤条件等因素有关。 相似文献
630.
节约型社会提出的现实背景、理论前提及其法律内涵 总被引:2,自引:0,他引:2
崔金星 《城市环境与城市生态》2006,(5)
通过对节约型社会提出的现实背景的阐述,认为节约型社会的理论前提和基础有生态政治理论、环境资源承载能力理论、资源生态经济理论、资源生态化和环境资源化理论等。并对节约型社会的目标、节约型社会的理念、基本原则等进行了探讨。最后在以上分析的基础上对节约型社会的法律内涵进行界定。认为节约型社会在第一层面的涵义是以供定需的发展战略和资源禀赋导向型的发展规划;第二层面的内涵是资源生态承载能力范围内的经济发展道路选择;第三层面的内涵是对自然资源进入社会经济生产的全过程进行规划和调控。 相似文献