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61.
Akata N Kakiuchi H Shima N Iyogi T Momoshima N Hisamatsu S 《Journal of environmental radioactivity》2011,102(9):837-842
This study aimed at obtaining background tritium concentrations in precipitation and air at Rokkasho where the first commercial spent nuclear fuel reprocessing plant in Japan has been under construction. Tritium concentration in monthly precipitation during fiscal years 2001-2005 had a seasonal variation pattern which was high in spring and low in summer. The tritium concentration was higher than that observed at Chiba City as a whole. The seasonal peak concentration at Rokkasho was generally higher than that at Chiba City, while the baseline concentrations of both were similar. The reason for the difference may be the effect of air mass from the Asian continent which is considered to have high tritium concentration. Atmospheric tritium was operationally separated into HTO, HT and hydrocarbon (CH3T) fractions, and the samples collected every 3 d-14 d during fiscal year 2005 were analyzed for these fractions. The HTO concentration as radioactivity in water correlated well with that in the precipitation samples. The HT concentration was the highest among the chemical forms analyzed, followed by the HTO and CH3T concentrations. The HT and CH3T concentrations did not have clear seasonal variation patterns. The HT concentration followed the decline previously reported by Mason and Östlund with an apparent half-life of 4.8 y. The apparent and environmental half-lives of CH3T were estimated as 9.2 y and 36.5 y, respectively, by combining the present data with literature data. The Intergovernmental Panel on Climate Change used the atmospheric lifetime of 12 y for CH4 to estimate global warming in its 2007 report. The longer environmental half-life of CH3T suggested its supply from other sources than past nuclear weapon testing in the atmosphere. 相似文献
62.
The Geological Survey of Sweden (SGU) has been conducting airborne gamma spectrometry measurements of natural radioactivity in Sweden for more than 40 years. Today, the database covers about 80% of the country’s land surface. This article explores the first step of putting this data into use in radioactive source search at ground level. However, in order to be able to use the airborne background measurements at ground level, SGU data must be validated against terrestrial data. In this work, we compare the SGU data with data measured by a portable backpack system. This is done for three different areas in southern Sweden. The statistical analysis shows that a linear relationship and a positive correlation exist between the air and ground data. However, this linear relationship could be revealed only when the region possessed large enough variations in areal activity. Furthermore, the activity distributions measured show good agreement to those of SGU. We conclude that the SGU database could be used for terrestrial background assessment, given that a linear transfer function is established. 相似文献
63.
用镍矿渣生产建筑砌块研究 总被引:3,自引:1,他引:3
以碱激发磨细镍矿渣作为胶结材料,用破碎后的镍矿渣作为集料,研究了镍矿渣含量为94%,抗压强度达289MPa的镍矿渣建筑砌块。该种建筑砌块的研制成功,为镍矿渣的处理,开辟了一条途径。 相似文献
64.
An inventory of N(2)O emissions from agriculture in China using precipitation-rectified emission factor and background emission 总被引:5,自引:0,他引:5
Fertilized agricultural soils are a major anthropogenic source of atmospheric N2O. A credible national inventory of agricultural N2O emission would benefit its global strength estimate. We compiled a worldwide database of N2O emissions from fertilized fields that were consecutively measured for more than or close to one year. Both nitrogen input (N) and precipitation (P) were found to be largely responsible for temporal and spatial variabilities in annual N2O fluxes (N2O–N). Thus, we established an empirical model (N2O–N = 1.49 P + 0.0186 P · N), in which both emission factor and background emission for N2O were rectified by precipitation. In this model, annual N2O emission consists of a background emission of 1.49 P and a fertilizer-induced emission of 0.0186 P · N. We used this model to develop a spatial inventory at the 10 × 10 km scale of direct N2O emissions from agriculture in China. N2O emissions from rice paddies were separately quantified using a cropping-specific emission factor. Annual fertilizer-induced N2O emissions amounted to 198.89 Gg N2O–N in 1997, consisting of 18.50 Gg N2O–N from rice paddies and 180.39 Gg N2O–N from fertilized uplands. Annual background emissions and total emissions of N2O from agriculture were estimated to be 92.78 Gg N2O–N and 291.67 Gg N2O–N, respectively. The annual direct N2O emission accounted for 0.92% of the applied N with an uncertainty of 29%. The highest N2O fluxes occurred in East China as compared with the least fluxes in West China. 相似文献
65.
阐述了应用发光细菌检测有色水样毒性时,水样色度会引起附加发光抑制的原因,提出应用同心双层检测玻管,可以对有色水样色度引起的附加发光抑制加以修正.通过比较单层管和双层管测定标准曲线间的差异、设置阴性对照和阳性对照评价该方法的可靠性,以及用该方法检测有色水样活性黑KN-B溶液的急性毒性实验,结果表明,用同心双层检测玻管可以有效修正由水样色度引起的附加发光抑制. 相似文献
66.
The magnetic properties of tree leaves along with their ecological, economical and aesthetic importance can be used to control
road derived respirable particulates. Isothermal remanent magnetization (IRM300 mT) of three different tree leaves viz. Mango (Mangifera indica), Sisso (Dalbergia sisso) and Banyan (Ficus benghalensis) were determined and IRM300 mT normalized for the leaf area. The normalized 2-D magnetization of leaves as shown by results is dominantly controlled
by leaf morphology and traffic density. F. benghalensis (Banyan) leaf has highest 2-D magnetization and D. sisso (Sisso) leaf having least 2-D magnetization suggesting greater ability of F. benghalensis (Banyan) tree leaves to reduce magnetic particulates. The particle size of the magnetic grains falls in the category of PM2.5,
a particle size hazardous to human health due to its capacity to be inhaled deeply into the lungs. 相似文献
67.
黄浦江上游优先控制有机物的筛选 总被引:6,自引:1,他引:6
参考国内外同行有关控制物的筛选方法,通过黄浦江上游饮用水源保护区内水质的污染现状分析,确立了黄浦江上游水源保护区优先控制污染物的筛选原则和筛选程序,建立了黄浦江上游工业废水和地面水中的优先控制的名单。 相似文献
68.
69.
Some characteristics of the distribution of heavy metals
in urban topsoil of Xuzhou,China 总被引:3,自引:0,他引:3
An assessment is presented of distribution characteristics of heavy metals in the urban topsoil from the city of Xuzhou. The
concentrations of Ag, Al, As, Au, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Ga, Hg, Li, Mn, Mo, Ni, Pb, Pd, Pt, Sb, Sc, Se, Sn, V and
Zn have been determined from 21 soil samples. Examination of lognormal distribution plots indicates that the diagrams of Al,
Be, Fe, Ga, Li, and V are almost linear suggesting that these metals are almost unaffected by anthropogenic activities while
the plots for As, Cd, Cu, Pb, Pd, Pt, Se, Zn and others are not linear probably due to anthropogenic activities from which
these metals are delivered to the soils. Al is used for mineralogical normalization of these data. An evaluation of background
values for topsoil is also carried out by means of lognormal distribution plots. The results show our background values obtained
from the lognormal distribution plots are comparable to those values of uncontaminated soils of Xuzhou obtained by previous
work except for Cd and Hg. At present, no explanation for the exceptions Cd and Hg can be given. 相似文献
70.
Geochemical mapping is a technique rooted in mineral exploration but has now found worldwide application in studies of the
urban environment. Such studies, involving multidisciplinary teams including geochemists, have to present their results in
a way that nongeochemists can comprehend. A legislatively driven demand for urban geochemical data in connection with the
need to identify contaminated land and subsequent health risk assessments has given rise to a greater worldwide interest in
the urban geochemical environment. Herein, the aims and objectives of some urban studies are reviewed and commonly used terms
such as baseline and background are defined. Geochemists need to better consider what is meant by the term urban. Whilst the
unique make up of every city precludes a single recommended approach to a geochemical mapping strategy, more should be done
to standardise the sampling and analytical methods. How (from a strategic and presentational point of view) and why we do
geochemical mapping studies is discussed.
相似文献
Christopher C. JohnsonEmail: |