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101.
人们对于与城市雨水有关的非点状源污染的关注,促使更好地规划水质的新工具得到了发展。本文介绍GIS在城市水质研究中的应用。这种GIS用于管理非点状源污染模型的土地利用数据,还可用于总计各种地理单元之中污染物的负荷量,在土地利用的基础上用水质经验模型来估算污染负荷量。通过判读最新的航空像片更新旧图从而编出土地利用图。这种土地利用图同样也可用来记录每个土地利用多边形的所有污染负荷量。通过对雨水沟图的数字 相似文献
102.
本文叙述的是釜石矿山的Nippo和Shinyama矿术带状矽卡岩中稀土元素的分布习性。带状矽卡岩在长岩和石岩中同样发育,但矽卡岩中稀土的丰度从闪长岩这边到石灰岩那边逐渐降低所有矽卡岩的稀土元素含量都比闪长岩中更低,也就是说矽卡岩的稀土元素来源于闪长岩,而热液流体中不增加或少量增加矽卡岩中的稀土元素的含量。 相似文献
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为了測定至对岸水边綫的水面寬度,或测定至岸边冰、浮冰或浮标的水面距离,以及当進行水文地理、水文測驗和測量工作时都可采用这个方法(圖1)。 相似文献
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106.
The dose-response relationship between No. 2 fuel oil and the growth of the salt marsh grass,Spartina alterniflora 总被引:1,自引:0,他引:1
The effect of No. 2 fuel oil on the biomass production of the salt marsh plant, Spartina alterniflora, was studied in a greenhouse dose-response experiment. S. alterniflora were transplanted into soil with 10 dosage levels of No. 2 fuel oil ranging from 0 to 456 mg g(-1) dry soil. Three months after transplantation, values for plant biomass, stem density, and shoot height decreased significantly with increasing fuel oil level in a dose-response fashion. Evapo-transpiration rates were correlated with the total biomass response. Relative to the control, a significant decrease in total (above- plus below-ground) plant biomass was observed at concentrations above 57 mg g(-1) dry soil. Within the 3-month experimental period, detrimental effects on below-ground biomass accumulation and bioluminescence of the marine bacterium Viberio fisheri in the Microtox Solid Phase Test were observed at oil concentrations >29 mg g(-1) dry soil, suggesting that biological effects of oil within the sediment matrix may be more pronounced than on above-ground biomass, requiring a dosage 228 mg g(-1) dry soil to elicit a significant detrimental effect. Hence, measurements of oil effects with biological end-points based solely on above-ground responses may underestimate the potential impacts of petroleum hydrocarbon spills, especially when the oil has penetrated the soil. While S. alterniflora was proved to be relatively tolerant to the No. 2 fuel oil spills, its effectiveness in phytoremediation operations may be limited at fuel oil levels 228 mg g(-1) dry soil, as both plant growth and microbial activity may be constrained. 相似文献
107.
Peterson JB Griffin GS Newcomb MG Alvarez DL Cantalupo CM Morgan D Miller KW Ganga K Pernic D Thoma M 《The Astrophysical journal》2000,535(2):L83-L86
Using all available major samples of Seyfert galaxies and their corresponding closely matched control samples of nonactive galaxies, we find that the bar ellipticities (or axial ratios) in Seyfert galaxies are systematically different from those in nonactive galaxies. Overall, there is a deficiency of bars with large ellipticities (i.e., "thin" or "strong" bars) in Seyfert galaxies compared to nonactive galaxies. Accompanied with a large dispersion due to small number statistics, this effect is strictly speaking at the 2 sigma level. To obtain this result, the active galaxy samples of near-infrared surface photometry were matched to those of normal galaxies in type, host galaxy ellipticity, absolute magnitude, and, to some extent, redshift. We discuss possible theoretical explanations of this phenomenon within the framework of galactic evolution, and, in particular, of radial gas redistribution in barred galaxies. Our conclusions provide further evidence that Seyfert hosts differ systematically from their nonactive counterparts on scales of a few kiloparsecs. 相似文献
108.
Very recently the Chandra first light observation discovered a point-like source in the Cassiopeia A supernova remnant. This detection was subsequently confirmed by the analyses of the archival data from both ROSAT and Einstein observations. Here we compare the results from these observations with the scenarios involving both black holes (BHs) and neutron stars (NSs). If this point source is a BH, we offer as a promising model a disk-corona type model with a low accretion rate in which a soft photon source at approximately 0.1 keV is Comptonized by higher energy electrons in the corona. If it is an NS, the dominant radiation observed by Chandra most likely originates from smaller, hotter regions of the stellar surface, but we argue that it is still worthwhile to compare the cooler component from the rest of the surface with cooling theories. We emphasize that the detection of this point source itself should potentially provide enormous impacts on the theories of supernova explosion, progenitor scenario, compact remnant formation, accretion to compact objects, and NS thermal evolution. 相似文献
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110.
Hurley K Strohmayer T Li P Kouveliotou C Woods P van Paradijs J Murakami T Hartmann D Smith I Ando M Yoshida A Sugizaki M 《The Astrophysical journal》2000,528(1):L21-L23
We present a 2-10 keV ASCA observation of the field around the soft gamma repeater SGR 1627-41. A quiescent X-ray source, whose position is consistent both with that of a recently discovered BeppoSAX X-ray source and with the Interplanetary Network localization for this soft gamma repeater, was detected in this observation. In 2-10 keV X-rays, the spectrum of the X-ray source may be fit equally well by a power-law, blackbody, or bremsstrahlung function, with unabsorbed flux approximately 5x10-12 ergs cm-2 s-1. We do not confirm a continuation of a fading trend in the flux, and we find no evidence for periodicity, both of which were noted in the earlier BeppoSAX observations. 相似文献