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81.
于2016年7月-2017年6月在武汉市典型居民区对大气中101种挥发性有机物(VOCs)进行了监测,以便研究武汉市典型居民区周边VOCs的组成特征和变化规律,并探讨了其主要来源.结果表明,武汉市空气中VOCs的体积分数为(46.24±24.57)×10-9,表现为烷烃>含氧有机物>烯烃>卤代烃>芳香烃.受交通排放影响烷烃的比例上午高于下午,1月机动车尾气为武汉市主要的VOCs排放源,夏季含氧类化合物浓度高于冬季,可能更多地受本地喷涂等溶剂使用行业和光化学反应生成的影响,5-9月表现出明显的生物源排放特征.利用正交矩阵因子分析(PMF)得到武汉市居民区大气VOCs主要有6个来源,分别为燃烧源、机动车尾气、工业排放、溶剂使用、汽油挥发和植物排放.其中,燃烧源、机动车尾气贡献比例最高,是该区域VOCs控制的重要排放源. 相似文献
82.
Effects of groundwater level fluctuation on its chemical composition in karst soils of Lithuania 总被引:3,自引:0,他引:3
Groundwater regime and mineralization process in moraine sandy loam and peat soils of the active sulphatic karst zone (karst
processes develop in the Upper Devonian gypsum–dolomites) in Lithuania and the dependence of chemical compounds concentrations
on water level fluctuations are reviewed. According to ion sum, groundwater mineralization in peat soil is 1.1–1.3 times higher
than in loam soil. Based on this result, lower levels of groundwater predetermine a more intensive mineralization process.
A stronger correlation was determined between groundwater levels and concentrations of chemical compounds (Ca2+, Mg2+, SO4
2− and HCO3
−) enhancing groundwater mineralization. In mineral soil (sandy loam) nitrate (NO3)− concentration is highly influenced by changing stages of groundwater level as well as by nearby sinkholes. 相似文献
83.
Multiple chemical constituents (nutrients; N, O, H, C stable isotopes; 64 organic wastewater compounds, 16 pharmaceutical
compounds) and microbiological indicators were used to assess the impact on groundwater quality from the land application
of approximately 9.5 million liters per day of treated municipal sewage effluent to a sprayfield in the 960-km2 Ichetucknee Springs basin, northern Florida. Enriched stable isotope signatures (δ18O and δ2H) were found in water from the effluent reservoir and a sprayfield monitoring well (MW-7) due to evaporation; however, groundwater
samples downgradient from the sprayfield have δ18O and δ2H concentrations that represented recharge of meteoric water. Boron and chloride concentrations also were elevated in water
from the sprayfield effluent reservoir and MW-7, but concentrations in groundwater decreased substantially with distance downgradient
to background levels in the springs (about 12 km) and indicated at least a tenfold dilution factor. Nitrate-nitrogen isotope
(δ15N–NO3) values above 10 ‰ in most water samples were indicative of organic nitrogen sources except Blue Hole Spring (δ15N–NO3 = 4.6–4.9 ‰), which indicated an inorganic source of nitrogen (fertilizers). The detection of low concentrations the insect
repellent N,N-diethyl-metatoluamide (DEET), and other organic compounds associated with domestic wastewater in Devil’s Eye Spring indicated
that leakage from a nearby septic tank drainfield likely has occurred. Elevated levels of fecal coliforms and enterococci
were found in Blue Hole Spring during higher flow conditions, which likely resulted from hydraulic connections to upgradient
sinkholes and are consistent with previoius dye-trace studies. Enteroviruses were not detected in the sprayfield effluent
reservoir, but were found in low concentrations in water samples from a downgradient well and Blue Hole Spring during high-flow
conditions indicating a human wastewater source. The Upper Floridan aquifer in the Ichetucknee Springs basin is highly vulnerable
to contamination from multiple anthropogenic sources throughout the springs basin. 相似文献
84.
Superfine graphite powder was prepared by ball-milling exfoliated graphite containing anhydrous CuCl2 in planetary ball milling systems. Nano-scale CuCl2 graphite intercalation compounds were synthesized by heating a mixture of anhydrous CuCl2 and graphite nanosheets. Scanning electron microscopy, energy-dispersive X-ray spectroscopy and high-resolution transmission electron microscopy were performed to characterize the microstructures of stage-1 nano-scale CuCl2 graphite intercalation compounds. The structure and components of the domain wall and core in the nano-scale CuCl2 graphite intercalation compounds are described. The results show that the content of CuCl2 in the mixture plays a crucial role in the size of the nano-scale CuCl2 graphite intercalation compound. 相似文献
85.
J. Kesselmeier 《Journal of Atmospheric Chemistry》2001,39(3):219-233
Field and laboratory investigations of the exchange of the short-chain organic acids – formic acid and acetic acid – as well as their homologous aldehydes are discussed. Both acids are substantially released from several plant species. Emission measurements under field conditions are compiled to give an overview of three years of measurements. Emission rates from several tree species were found in the range between zero and 60 nmoles m–2 min–1 for acetic acid and between zero and 90 nmoles m–2 min–1 for formic acid though also a deposition has been observed to orange trees. Investigations under laboratory conditions showed an order of magnitude lower emission rates with significant differences under light and dark conditions, and a deposition was observed under certain conditions. Hence, low emission rates or even a bi-directional exchange, emission as well as deposition have to be taken into account. Further differences between field and laboratory studies are discussed considering age of trees, stress effects and a potential production of acids by photochemical conversion of precursors inside enclosures during sampling. Field data on the exchange of form- and acetaldehyde show a complex behavior. We found emission as well as uptake. The bi-directional exchange is significantly triggered by the ambient mixing ratios of both aldehyde species and exhibits a compensation point. Further studies are needed for generalization of the exchange of these and potentially also for other compounds. 相似文献
86.
氢化物发生—原子荧光法直接测定锑及其化合物中的铅 总被引:1,自引:0,他引:1
通过在样品处理阶段用HBr除去大量锑基体,实现了不需再通过其他化学分离直接运用氢化物发生-原子荧光法测定锑及其相关产品中的微量铅,并用于实际样品的分析.该方法对样品检测下限小于10-6,在实际样品分析中,分析结果与原子吸收法测定结果之间无显著性差异,RSD<2.0%(n=4),对样品分析的加标回收率在95%~105%. 相似文献
87.
胜利油田孤岛原油中有机硅化合物的发现及其石油地质意义 总被引:7,自引:0,他引:7
采用溶剂萃取法从胜利油田孤岛原油中分离得到浓缩的含氧化合物,再用柱色谱分离得到有机硅及其它组分。用红外、电子能谱、气相色谱-质谱法分离鉴定了有机硅组分。鉴定出的有机硅化合物有硅Si3-Si7的甲基硅氧烷和Si3-Si5的环甲基硅氧烷以及三甲基硅的衍生物。资料表明:在高等和低等生物体中还不能肯定含有Si-C键的有机化合物。因此,原油中有机硅化合物的发现是原油无机成因的一个证据。本文还简要讨论了位于勃海湾盆地孤岛原油的无机成因的地质环境及其石油地质意义。 相似文献
88.
S. Derenne C. Largeau E. Casadevall J.S. Sinninghe Damst E.W. Tegelaar J.W. de Leeuw 《Organic Geochemistry》1990,16(4-6)
The kerogen of a sample of Estonian Kukersite (Ordovician) was examined by spectroscopic (solid state 13C NMR, FTIR) and pyrolytic (“off-line”, flash) methods. This revealed an important contribution of long, linear alkyl chains in Kukersite kerogen. The hydrocarbons formed upon pyrolysis are dominated by n-alkanes and n-alk-1-enes and probably reflect a major contribution of selectivity preserved, highly aliphatic, resistant biomacromolecules from the outer cell walls of Gloeocapsomorpha prisca. This is consistent with the abundant presence of this fossilized organism in Kukersite kerogen. In addition high amounts of phenolic compounds were identified in the pyrolysates. Series of non-methylated, mono-, di- and trimethylated 3-n-alkylphenols, 5-n-alkyl-1,3-benzenediols and n-alkylhydroxybenzofurans were identified. All series of phenolic compounds contain long (up to C19), linear alkyl side-chains. Kukersite kerogen is, therefore, an aliphatic type II/I kerogen, despite the abundance of free phenolic moieties. This study shows that phenol-derived moieties are not necessarily associated with higher plant-derived organic matter.The flash pyrolysate of Kukersite kerogen was also compared with that of the kerogen of the Guttenberg Oil Rock (Ordovician) which is also composed of accumulations of fossilized G. prisca. Similarities in the distributions of hydrocarbons and sulphur compounds were noted, especially for the C1–C6 alkylbenzene and alkylthiophene distributions. However, no phenolic compounds were detected in the flash pyrolysate of the Guttenberg kerogen. Possible explanations for the observed similarities and differences are discussed. 相似文献
89.
从松节藻中分离的含卤素化合物表现出显著PTP1B抑制活性。其中BPN效果最佳。为研究BPN侧链基团极性对其抑制活性的影响,本文以香兰素(1)为起始原料,经过溴代、氧化、还原、傅克烷基化以及酯化等反应,成功合成了新化合物2,3-二溴-1-(2-溴-3,4-二甲氧基-6-((4-硝基苯氧基)甲基)苯甲基)-4,5-二甲氧基苯(10)、4-((3-溴-2-(2,3-二溴-4,5-二甲氧基苄基)-4,5-二甲氧基苄基)醚)苯胺(11)、4-((3-溴-2-(2,3-二溴-4,5-二甲氧基苄基)-4,5-二甲氧基苄基)醚)-4-乙酰乙酸(12)和3-溴-2-(2,3-二溴-4,5-二甲氧基苄基)-4,5-二甲氧基苯甲醛肟(14)。通过1 H-NMR,13C-NMR等方法对目标产物进行了结构表征。并对化合物进行了PTP1B酶抑制活性的测定,结果表明化合物侧链极性对PTP1B酶抑制活性有显著影响。 相似文献
90.