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991.
992.
K. Mannschreck K. Bächmann K. H. Becker Th. Heil R. Kurtenbach M. Memmesheimer V. Mohnen A. Obermeier D. Poppe R. Steinbrecher Th. Schmitz A. Volz-Thomas F. Zabel 《Journal of Atmospheric Chemistry》2002,42(1):281-286
The database for volatile organic compounds (VOC data base) was created with the aim of providing an overview of tropospheric hydrocarbon measurements. The data base contains 202 substances, for which atmospheric and useful kinetic data such as rate coefficients, photolysis frequencies, mixing ratios, emission data and ozone formation potentials are compiled from available literature. The database file can be downloaded without charge from http://www.physchem.uni-wuppertal.de/voc-database. Registered users will be informed about the appearance of updates. 相似文献
993.
R. Kurtenbach R. Ackermann K. H. Becker A. Geyer J. A. G. Gomes J. C. Lörzer U. Platt P. Wiesen 《Journal of Atmospheric Chemistry》2002,42(1):395-411
In 1997 and 1998 several field campaigns for monitoring non-methane volatile organic compounds (NMVOCs) and nitrogen oxides (NOx) were carried out in a road traffic tunnel and in the city center of Wuppertal, Germany. C2–C10 aliphatic and aromatic hydrocarbons were monitored using a compact GC instrument. DOAS White and long path systems were used to measure aromatic hydrocarbons and oxygenated aromatic compounds. A formaldehyde monitor was used to measure formaldehyde. Chemiluminescence NO analysers with NO2 converter were used for measuring NO and NO2. The high mixing ratios of the NMVOCs observed in the road traffic tunnel, especially 2.9 ppbv phenol, 1.5ppbv para-cresol and 4.4 ppbv benzaldehyde, in comparison with themeasured background concentration clearly indicate that these compounds were directly emitted from road traffic. Para-Cresol was for the first timeselectively detected as primary pollutant from traffic. From the measured data a NMVOC profile of the tunnel air and the city air, normalised to benzene (ppbC/ppbC), was derived. For most compounds the observed city air NMVOC profile is almost identical with that obtained in the traffic tunnel. Since benzene originates mainly from road traffic emission, the comparison of the normalised emission ratios indicate that the road traffic emissions in Wuppertal have still the largest impact on the city air composition, which is in contrast to the German emission inventory. In both NMVOC profiles, aromatic compounds have remarkably large contributions of more than 40 ppbC%. In addtion, total NMVOC/NOx ratios from 0.6 up to 3.0ppbC/ppb in the traffic tunnel air and 3.4± 0.5 in the city air of Wuppertal were obtained. From the observed para-cresol/toluene and ortho-cresol/toluene ratios in the city air, evidence was found thatalso during daytime NO3 radical reactions play an important role in urban air. 相似文献
994.
Environmental records of carbon in recent lake sediments 总被引:4,自引:0,他引:4
Based on careful sampling and accurate analysis of recent sediments in Lake Chenghai, this paper discusses the staggered positive/negative
correlation between organic carbon (OC) concentration and inorganic carbon (IC) concentration. The result indicates that temperature
change, and its induced relative changes are the main factors affecting the relationship between IC concentration, δ13C of carbonate and OC concentration. When temperature and its induced photosynthesis strength change control autochthonous
calcite precipitation, OC concentration is positively correlated with IC concentration and δ13C of carbonate. When temperature and its induced physical/chemical changes dominate, OC concentration displays negative correlation
with IC concentration and δ13C of carbonate. IC concentration and δ13C of carbonate in sediments of Lake Chenghai are good proxies for climatic warm/cold changes. 相似文献
995.
Yang Guifang Yin Hongfu Li ChanganFaculty of Earth Sciences China University of Geosciences Wuhan 《中国地质大学学报(英文版)》2002,(1)
The Hongzuisi Section in Lanzhou area is used to infer the paleoclimate since the late glacial epoch. Through combined analysis of organic carbon isotope and CaCO3 content, paleoenvironment evolution of Hongzuisi Section since the late glacial epoch is discussed. There were changes in both dry-moist and warm-cold. Especially the climate changes can be compared with synchronous sections of other areas, which provides useful information for our future forecast. 相似文献
996.
岩石样品中有机物的超临界萃取行为 总被引:1,自引:0,他引:1
对不同有机碳含量的岩石中的有机化合物进行了超临界萃取行为研究,探讨了超临界萃取压力,温度,时间对化合物溶出行为的影响。岩石样品经CO2超临界萃取,三氯甲烷索氏提取后,对提取物进行气相色谱/质谱分离测定。应用地球化学参数和质量色谱图对超临界萃取和索氏提结果进行了比较。结果表明,超临界萃取在对岩石中低碳饱和烃化合物的萃取上显示了优势;对总有机磷含量较高的样品,两种提取方法的结果显示了很好的一致性;对总有机碳含量较低的样品,超蟠对一些化合物的提取效果稍差。 相似文献
997.
998.
华南亚热带山地土壤有机质更新特征定量研究 总被引:12,自引:3,他引:12
选择鼎湖山自然保护区森林植被带(SL)、灌丛一草甸过渡带土壤剖面(GC)进行薄层取样,根据土壤有机质^14C放射性水平,运用模型计算土壤有机质更新速率(m)。结果表明上部0-10cm土层有机质更新速率(m)最高;向下,m锐减;剖面下部m值极低,这说明土壤有机质由不同更新周期(T)组分构成。表层快循环组分占绝对优势,向下,慢循环组分为主,剖面下部为稳定组分。根据m、有机碳含量、有机碳含量、土壤容重、土层厚度计算有机质更新CO2产量,表层0-10cm层段CO2产量约为整个剖面的98%。SL剖面m值及有机质更新CO2产量均明显大于GC剖面相应值。分析表明在同一气候植被是制约土壤有机质更新及CO2产量的第一要素,这为通过绿化加强土壤碳汇功能提供重要依据。 相似文献
999.
天目山泥炭有机碳同位素特征及其古环境意义 总被引:4,自引:1,他引:3
通过对浙江天目山泥炭剖面的高密度采样和有机碳同位素分析,重建了该地区4 ka BP以来的古植被特征和古环境演化历史.天目山3200 a BP之前,气候温和适度,晚期变冷变干,为中全新世末气候波动的过渡时期.3200~700 a BP,有机碳δ13Corg值在波动中降低,气候出现多次急剧冷暖变化,指示了几次温暖与寒冷事件.700 aBP以来,有机碳同位素迅速正偏,表明又一暖期的出现,到了后期气温又有所降低,植被转化为草原草甸景观.天目山地区近4 ka以来的气候变化与国内外不同区域的研究资料相一致,但又有区域的差异性. 相似文献
1000.