Trace gas exchange at the air/water interface: Measurements of mass accommodation coefficients     

W. Kirchner  F. Welter  A. Bongartz  J. Kames  S. Schweighoefer  U. Schurath 《Journal of Atmospheric Chemistry》1990,10(4):427-449

A liquid jet of 90 m diameter and variable length has been utilized to determine absorption rates and, hence, mass accommodation coefficients , of atmospheric trace gases. The compounds investigated are HCl (0.01), HNO₃ (0.01), N₂O₅ (0.005), peroxyacetyl nitrate (>0.001), and HONO (0.005). It is concluded that the absorption of these trace gases by liquid atmospheric water is not significantly retarded by interfacial mass transport. The strengths and limitations of the liquid jet technique for measuring mass accommodation coefficients are explored.  相似文献   

Typological analysis of demographic changes in the Tuscan communes     

Bottai M  Costa M  Formentini U 《Rivista geografica italiana》1978,85(4):321-347

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Assessment of the mycoflora of commercial poultry feeds sold in the humid tropical environment of Imo State, Nigeria     

I. C. Okoli DVM  M. Sc.  Ph.D.  C. U. Nweke B.S. Agric. Tech.  C. G. Okoli B.Sc  M. Sc.  Ph.D.  M. N. Opara DVM  M.Sc 《International Journal of Environmental Science and Technology》2006,3(1):9-14

This study was carried out to identify the common moulds growing in selected commercial poultry feed sold in Owerri, Imo State, Nigeria. Forty-eight bulk samples derived froml92 bags of feeds were collected from broiler starter (BS), broiler finishers (BF), grower mash (GM) and layer mash (LM) across 4 different brands of ommercial poultry feeds, which included Livestock (LF), Top (TF) Guinea (GF) and Vital (VF) feeds. The feed samples were collected during the rainy season months of June, July and August. The common moulds isolated from these feeds were Aspergillus sp., Peicillium sp.,Mucor sp., Yeast sp., Rhizopus sp., Epicoecum sp., Gymnoaseus sp., Cladosporium sp., Mortierella sp. as well as Bacteria. Generally, more organisms were isolated in June than the other months with Mortierella sp. being the only one not isolated in that month. Vital feed with 8 different isolates had the highest diversity of fungal species while the others had between 4 and 5 species. Prevalence rates across the feed types, generally ranged from 18.76% in layer mash to 30.03% in broiler finisher. The four Aspergillus sp. isolated came from GM and BF. This study highlights the need for constant monitoring of moulds in commercial feedstuff produced in the humid tropical environments such as Imo state, Nigeria. There is also the need to routinely include fungal growth nhibitors in commercial feeds since moulds are capable of reducing the nutritional values of feedstuff as well as elaborating pathogenic toxins.  相似文献   

Alpine reworking of Ordovician protoliths in the Western Carpathians: Geochronological and geochemical data on the Muráñ Gneiss Complex, Slovakia     

A.S. Gaab  M. Jank  U. Poller  W. Todt 《Lithos》2006,87(3-4):261-275

Magmatic protoliths of Ordovician age have been identified in the metamorphic rocks of the Muráñ Gneiss Complex, Veporic Unit (Central Western Carpathians). Vapor digestion single zircon U–Pb dating yields an intrusion age of 464 ± 35 Ma (upper intercept) for the granite protolith. A lower intercept age of 88 ± 40 Ma records amphibolite-facies metamorphic overprint in the Cretaceous, during the Alpine orogeny. Geochemical and isotopic data suggest crustal origin of the orthogneiss. Nd_initial are between − 2.6 and − 5.0 and T_DM^Nd between 1.3 and 1.5 Ga (two-step approach). ⁸⁷Sr / ⁸⁶Sr_initial ratios vary between 0.7247 and 0.7120, and a steep REE pattern further constrains the crustal affinity of these rocks. Associated amphibolite bodies have Nd_initial values of 6.5, ⁸⁷Sr / ⁸⁶Sr_initial ratio of 0.7017, and a flat REE pattern. They are interpreted as MORB derived metabasites. Whole-rock Pb isotope analyses define a linear array in a ²⁰⁶Pb / ²⁰⁴Pb vs. ²⁰⁷Pb / ²⁰⁴Pb diagram with an age of ca. 134 Ma, consistent with intense Alpine metamorphism and deformation.

These basement rocks of the Central Western Carpathians are interpreted as Ordovician magmatic rocks intruded at an active margin of Gondwana. They represent the eastern prolongation of Cambro–Ordovician units of the European Variscides, which were part of the peri-Gondwana superterrane and accreted to Laurussia during the Variscan orogeny. Variscan metamorphic overprint is not recorded by the isotopic data of the Muráñ Gneiss Complex. Alpine metamorphism is the most dominant overprint.  相似文献   

The Usage of Ground Penetrating Radar (GPR) in Designing Blast Pattern     

G. U. Aldas  S. Kadioglu  E. Ulugergerli 《Rock Mechanics and Rock Engineering》2006,39(3):281-290

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The First Appearance of Cattle in Denmark Occurred 6000 Years Ago: An Effect of Cultural or Climate and Environmental Changes     

Nanna Noe-Nygaard  Mikkel U. Hede 《Geografiska Annaler: Series A, Physical Geography》2006,88(2):87-95

Stable carbon and nitrogen isotope ratios from bones of contemporaneous Late Atlantic aurochs and early cattle in eastern Denmark are significantly different and provide information on the origin and feeding strategies of the earliest domestic cattle. The data show that the early cattle were feeding on grass right from the beginning 4000 cal. yr BC. In contrast, the youngest aurochs population primarily browsed and grazed from the dense forest floor resulting in rather negative δ¹³C values measured on bone collagen. The oldest aurochs have similar isotope values to the earlier cattle, whereas the youngest aurochs have similar values to Late Atlantic red deer from the same locality. As eastern Denmark was largely covered by forest, speculations on the origin of the grazing areas are many. The grass may have grown in openings in the forest, at the forest fringe, or more likely on the newly reclaimed coastal land areas exposed by the decreasing rate of eustatic sea‐level rise contemporaneously with isostatic uplift, during the Littorina transgressions. The stable isotope values do not indicate that leaf foddering of the early cattle was of importance.  相似文献   

Effect of lithospheric root on decompression melting in plume–lithosphere interaction models     

A. Manglik  U. R. Christensen 《Geophysical Journal International》2006,164(1):259-270

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Stratigraphy, sedimentology and bulk organic geochemistry of black shales from the Proterozoic Vindhyan Supergroup (central India)   总被引：1，自引：0，他引：1  

S. Banerjee  S. Dutta  S. Paikaray  U. Mann 《Journal of Earth System Science》2006,115(1):37-47

Four organic-rich shale units of the Proterozoic Vindhyan sedimentary succession have been scanned to reveal their origin and hydrocarbon potential. The wavy-crinkly nature of the carbonaceous laminae is suggestive of a microbial mat origin of the shales. These shales are thus different from Phanerozoic black shales which typically exhibit planar laminae. The hydrocarbon potential of the black shale units has been evaluated by Rock-Eval pyrolysis. Total organic carbon content of many of the shales exceeds 1%. The meanT _max for the black shales translate to a vitrinite reflectance range of 2.05-2.40% Rm based on standard conversion techniques. These shales have reached the catagenetic stage near the beginning of anthracite formation.  相似文献   

Petrogenesis and geotectonic setting of the PanAfrican basement rocks in Bamenda Massif, Obudu Plateau, southeastern Nigeria： Evidence from trace element geochemistry     

UKAEGBU V. U. EKWUEME B. N. 《中国地球化学学报》2006,25(2):122-131

1 IntroductionThe study area is part of the Obudu Plateau,which forms part of the Precambrian Pan-African tec-tonothermal belt, lying between the West African Cra-ton and the Gabon-Congo Craton ( Fig. 1). It isbounded by the Benue Trough, in the NE-SW axi…  相似文献   

模式水平分辨率对祁连山区降水模拟影响的初步分析   总被引：5，自引：3，他引：5  

李锁锁  吕世华  高艳红  张宇 《高原气象》2005,24(4):496-502

利用中尺度模式MM5V3．6，针对祁连山地区2002年7月14～17日的一次降水过程，设计了一组不同水平分辨率的试验进行数值模拟。并将模式结果与实测资料进行对比，结果表明：高水平分辨率对降水中心位置的模拟较好，但同时会产生虚假降水中心，且模拟的降水中心量值一般都大于实测值。而低水平分辨率对降水量值的模拟较好，但对降水中心位置的模拟没有高水平分辨率的好。  相似文献