45 resultados para volatile organic content
em Chinese Academy of Sciences Institutional Repositories Grid Portal
Resumo:
In this study, the levels of 25 semi-volatile organic compounds (SVOCs) were measured in samples of water, suspended particulate matter (SPM) and sediment from two urban lakes in Wuhan, China. The total concentrations of 25 SVOCs varied from 529.4 to 2168.9 ng/L, 120.7 to 22543.7 ng/g dry weight and 1577.3 to 61579.6 ng/g dry wt. in water, SPM and sediment, respectively. The concentration of SVOCs in SPM was 9-10 times higher than that in water, and the concentration of SVOCs in sediment 1.5-2 times higher than that in SPM. The level of total SVOC25 in the samples from Moshuihu Lake was higher than that in Yuehu Lake. Among the 25 SVOCs, phthalate compounds were on the highest level in all observed samples ranging between 441.9-1831.2 ng/L, 116.3-17566.8 ng/g, dry wt. and 6432.8-48177.6 ng/g dry wt. in water, SPM and sediment, respectively. Bis(2-ethylhexyl)phthalate, the predominant component of the analyzed pollutants, was in the range from 246.7 to 537.5 ng/l, 51.2 to 15540.0 ng/g dry wt. and 468.2 to 45010.3 ng/g dry wt. in water, SPM and sediment, respectively. The content of PAHs, dinitrotoluene and isophoton in sediment was higher than that in water and SPM at most of the locations. The possible sources of the pollutants and their inter-relation with human activities were discussed.
Resumo:
Fullerenes-extracted soot (FES) is the by-product of fullerenes production. Retention characteristics at different temperatures for 17 volatile organic compounds (VOCs) on FES are measured. The adsorption and desorption efficiencies for VOCs on FES adsorbent tubes range from 40.8 to 117%, most of them being 100+/-20%. The values are compared with Tenax GR, an adsorbent commonly used in environmental analysis. FES can be used as an adsorbent of low cost to collect VOCs in environmental samples. (C) 2000 Elsevier Science B.V. All rights reserved.
Resumo:
Gaseous and particulate semi volatile carbonyls have been measured in urban air using an annular denuder sampling system. Three dicarbonyls, five aliphatic aldehydes and two hydroxy carbonyls were observed. Concentrations of other biogenic and anthropogenic volatile organic compounds (VOCs), SO2, CO, NO2 and particle concentration were also measured. Estimated gas-aerosol equilibrium constants for the carbonyls showed an inverse correlation with the concentrations of anthropogenic pollutants such as benzene, isopentane and SO2. This suggests that the increase in the fraction of non-polar anthropogenic particles in the atmosphere could change the average property of the ambient aerosols and drive the gas particle equilibrium of the carbonyls to the gas phase. This trend is uncommon in remote forest air. In this study, we examined the factors controlling the equilibrium in the polluted atmosphere and show that there is a difference in gas-aerosol partition between polluted and clean air.
Resumo:
采用溶胶-凝胶法制作波导环形谐振腔, 讨论了环形谐振腔器件的传输特性。测量了在不同物质、不同体积分数的挥发性有机化合物(VOC)蒸气气氛下器件的传输光谱的敏感性。结果表明, 谐振波长随甲醇、乙醇、丙醇等醇类化合物, 以及丙酮、甲醛等蒸气体积分数的上升而向长波方向移动, 具有高的灵敏度, 且两者基本呈线性关系。其中, 对丙醇最敏感, 灵敏度达到1.403 pm/10-6。对甲烷和二甲苯也有微弱反应, 但是其灵敏度很低。也测量了水蒸气对传输谱特性的影响。观察到传输谱衬比度对不同挥发性有机化合物物质蒸气的不同敏
Resumo:
植物源挥发性有机碳化合物(Volitale organic compounds, VOC)是大气VOC的主要来源,与对流层大气质量、大气化学密切相关。鉴于温带草地的分布范围很广,草地植物VOC释放潜力某种程度上影响植物源VOC的总释放量。另外,植物源VOC也是光合作用固定碳素的损失方式之一,可能在特定区域或生态系统中具有重要意义。基于上述想法,本文设计了四个方面的实验作为研究内容:1) 温带草地物种水平VOC释放潜力、及其与植物功能群的关系?2) 沙地植物物种水平VOC释放潜力、及其与植物功能群的关系?3) 沙地植物-草地植物VOC释放潜力存在显著性差异吗?4) 温带典型草地和退化草地的VOC释放速率如何?在生态系统水平,植物源VOC对温带草地碳循环的贡献多大? 在所测定的175种温带草地植物中,不同植物间异戊二烯和单萜释放潜力差异很大;除少数物种外,大多数植物的异戊二烯和单萜释放潜力都较低,尤其是典型草地的优势物种。在此基础上,作者探讨了分类学赋值方法对温带草地植被的可行性,并初步建立了锡林河流域温带草地植物的VOC释放目录(共277种植物)。另外,温带草地植物的异戊二烯和单萜释放潜力与植物功能群(植物生活型和水分功能群)具有一定的联系,尤其是植物生活型。总的来说,温带草原的优势生活型(物种),即多年生根茎禾草(或多年生丛生禾草),具有较低的异戊二烯和单萜释放潜力。各水分功能群间差异不显著,但中旱生植物、旱中生植物 (温带草原的优势功能群),具有较低的异戊二烯、单萜释放潜力。因此,温带草原退化过程中,那些具有较高VOC释放潜力的植物,重要性将会增加。 沙地植物种类组成非常丰富,不同物种间的异戊二烯和单萜释放潜力变异也很大。另外,沙地植物的异戊二烯和单萜释放潜力与其功能群间关系较密切,不同植物生活型间差异显著;其中也以多年生根茎禾草、多年生从生禾草的释放潜力最低,而乔木的释放潜力相对最高;该结论基本与草地的研究结论一致。然而,沙地植物的异戊二烯和单萜释放潜力与其水分功能群的关系比较模糊,中生植物具有更高的释放潜力,湿生植物的释放潜力较小。 通过对比沙地植物和草地植物的释放潜力,发现沙地植物的异戊二烯和单萜释放潜力比草地植物高,且这种差异整体上显著。另外,这种显著性差异,在不同植物生活型、水分功能群间也同样存在。沙地植物比对应的草地植物具有更高的异戊二烯和单萜释放潜力,最可能的原因:沙地正午的温度明显比草地温度高,前者实测温度可超过 45 ℃,这种经常性、周期性高温,促使沙地植物采用与草地植物不同的适应策略,即沙地植物通过释放更多的异戊二烯或单萜来减少其可能遭的热胁迫或热伤害,这种长期适应策略,使沙地植物具有更高的萜类化合物释放潜力。 本文还调查了温带典型草地生态系统和退化草地生态系统的异戊二烯和单萜释放速率,结果表明典型草地的标准异戊二烯和单萜释放速率分别为0.50 μgC g-1 h-1和0.69 μgC g-1 h-1;退化草地的标准异戊二烯和单萜释放潜力分别为0.32 μgC g-1 h-1和1.59 μgC g-1 h-1。总的来说,温带草地的异戊二烯和单萜释放速率都比较低,尤其是典型草地。整个生长季,典型草地释放的异戊二烯和单萜分别为31.6 mgC•m-2 和 70.4 mgC•m-2;退化草地的异戊二烯和单萜释放量分别为20.8 mgC•m-2 和 168.8 mgC•m-2。退化草地萜类化合物总释放速率远高于典型草地,尤其是单萜释放能力。过度放牧引起的草地退化,通过改变植被种类组成,对温带草地的异戊二烯和单萜释放速率产生显著影响;总体而言,温带草地退化将会使草地释放更多萜类化合物。 在温带草地生态系统中,Clost as VOC相对其NPP而言很小,在环境PAR和温度高时,它的贡献率相对较大;Clost as VOC约占典型草地生态系统NEP的5.32 %,退化草地生态系统NEP的0.23 %。植物源VOC释放所损失的碳素相对草地生态系统NPP而言几乎可以忽略不计;但是,相对其NEP,Clost as VOC还是具有一定的相关性。虽然,草地生态系统Clost as VOC对NPP或NEP的贡献率较小,但考虑到全球尺度植物源VOC的巨大释放速率,它在碳循环中的贡献率仍然不容忽视;在某些特殊的生态系统中,仍可能扮演重要角色。
Resumo:
本文主要研究了沈阳市主要绿化树种银杏(Ginkgo biloba)和油松(Pinus tabulaeformis)挥发性有机物(Volatile Organic Compounds,VOCs)排放的日变化、季节变化规律,同时采用开顶箱法研究了高浓度CO2(700 µmol•mol-1)、O3(80 nmol•mol-1)及复合作用下城市主要绿化树种银杏、蒙古栎(Quercus mongolica)、油松、华山松(Pinus armandii)VOCs排放规律,揭示了城市中树木VOCs排放的变化规律及其对高浓度CO2和O3的响应,为研究城市森林对全球变化的响应与反馈提供了科学依据。 本实验建立的热解吸与气相色谱联用方法,最小检测量为4×10-10 g,具有较高的灵敏度和精确度,可满足对树木VOCs分析的要求。研究发现,银杏和油松VOCs的释放具有显著的日变化和季节变化规律,二者夜间均不排放异戊二烯。α-蒎烯为油松释放VOCs的主要成份,同时发现油松排放的α-蒎烯,β-蒎烯,莰烯和柠檬烯之间具有显著相关关系,说明这几种化合物在遗传控制上有某种共同效应或者具有相同的代谢途径。不同树种排放的VOCs组成明显不同,银杏及蒙古栎主要排放异戊二烯,而油松和华山松主要排放单萜;蒙古栎VOCs释放量显著高于其他树种。市区树木VOCs排放速率显著高于郊区,沈阳市主要绿化树种银杏和油松VOCs的年排放量分别为12.16 t和14.48 t。大气CO2和O3浓度升高条件下,树木VOCs释放规律和排放组成,受植物种类和生长季的影响;单独提高大气CO2或O3浓度可显著影响树木VOCs的释放和组成,但是二者复合作用没有显著影响。
Resumo:
本文采用热解吸与气相色谱联用技术对沈阳市主要绿化树种银中杨(Populus alba × berolinensis)、垂柳(Salix babylonica)、榆树(Ulmus pumila)、皂角(Gleditsia japonica)、丁香(Syringa oblate)和水腊(Ligustrum obtusifolium)植物源挥发性有机物(Biogenic Volatile Organic Compounds,BVOCs)排放的日变化、季节变化规律进行了观测,并估算了这6种树的BVOCs排放通量;同时采用开顶箱法研究了高浓度CO2(700 µmol•mol-1)、O3(80 nmol•mol-1)及二者复合作用下蒙古栎(Quercus mongolica)和油松(Pinus tabulaeformis)BVOCs排放规律。研究结果如下所示: (1) 6种绿化树种BVOCs的释放具有显著的日变化和季节变化规律,且夜间几乎均不排放异戊二烯。 (2) 不同树种排放的BVOCs组成明显不同,银中杨、垂柳和蒙古栎以排放异戊二烯为主;油松主要释放α-蒎烯;榆树、皂角和丁香以释放柠檬烯为主;水腊在不同时段其BVOCs组成情况变化较大,主要释放异戊二烯、柠檬烯和α-蒎烯;其中银中杨和垂柳的BVOCs释放量明显高于其它树种。 (3) 在实测数据基础上,估算出沈阳市6种主要绿化树种银中杨、垂柳、榆树、皂角、丁香和水腊在自然条件下的BVOCs年排放量分别为104.86tC,168.66tC,3.56tC,1.27tC,4.07tC和1.33tC。 (4) 大气CO2和O3浓度升高条件下,树木BVOCs释放规律和排放物组成受植物种类和生长季的影响;单独提高大气CO2或O3浓度可显著影响树木BVOCs的释放,二者的复合作用对BVOCs释放的影响主要介于两者单独作用的结果之间。
Resumo:
Eight cruises were conducted on the south Yellow Sea (SYS) from 1998 to 2005. Variations and the potential ecological risk of heavy metals were studied using the survey data collected during October 2003. The metal content (except for As) was high in the central area where the fine grain size sediments were dominant, and low inshore area where more coarse sediments were present. This suggested that grain size was important in determining distributions of heavy metals. In some local areas, other influencing factors, such as organic content, sedimentation rate, burial efficiency and metal's existing form were discussed. The annual averages of metals showed a stable trend with appreciable fluctuations in 8 years. Using potential ecological risk index (E (RI)) to evaluate the integrated pollution effect of heavy metals, 38.7% of the investigated area was in a moderate degree of contamination, while 77.8% was under moderate ecological risk. However, no distinct correlation was found between E (RI) and plankton biomass. In conclusion, the sediment quality of SYS was good, and the ecological risk was low in general.
Resumo:
Mudstone reservoir is a subtle reservoir with extremely inhomogeneous, whose formation is greatly related to the existence of fracture. For this kind of reservoir, mudstone is oil source rock, cover rock and reservoir strata, reservoir type is various, attitude of oil layer changes greatly, and the distribution of oil and gas is different from igneous or clastic rock reservoir as well as from carbonate reservoir of self-producing and self-containing of oil and gas. No mature experience has been obtained in the description, exploration and development of the reservoir by far. Taking Zhanhua depression as an example, we studied in this thesis the tectonic evolution, deposit characteristics, diagenesis, hydrocarbon formation, abnormal formation pressure, forming of fissure in mudstone reservoir, etc. on the basis of core analysis, physical simulation, numerical simulation, integrated study of well logging and geophysical data, and systematically analyzed the developing and distributing of mudstone fissure reservoir and set up a geological model for the formation of mudstone fissure reservoir, and predicted possible fractural zone in studied area. Mudstone reservoir mainly distributed on the thrown side of sedimentary fault along the sloping area of the petroleum generatiion depression in Zhanhua depression. Growing fault controlled subsidence and sedimentation. Both the rate of subsidence and thickness of mudstone are great on the thrown side of growing fault, which result in the formation of surpressure in the area. The unlocking of fault which leads to the pressure discharges and the upward conduct of below stratum, also makes for the surpressure in mudstone. In Zhanhua depression, mudstone reservior mainly developed in sub-compacted stratum in the third segment of Shahejie formation, which is the best oil source rock because of its wide spread in distribution, great in thickness, and rich in organic matter, and rock types of which are oil source mudstone and shale of deep water or semi-deep water sediment in lacustrine facies. It revealed from core analysis that the stratum is rich in limestone, and consists of lamina of dark mudstone and that of light grey limestone alternately, such rock assemblage is in favor of high pressure and fracture in the process of hydrocarbon generation. Fracture of mudstone in the third segment of Shahejie formation was divided into structure fracture, hydrocarbon generation fracture and compound fracture and six secondary types of fracture for the fist time according to the cause of their formation in the thesis. Structural fracture is formed by tectonic movement such as fold or fault, which develops mainly near the faults, especially in the protrude area and the edge of faults, such fracture has obvious directivity, and tend to have more width and extension in length and obvious direction, and was developed periodically, discontinuously in time and successively as the result of multi-tectonic movement in studied area. Hydrocarbon generation fracture was formed in the process of hydrocarbon generation, the fracture is numerous in number and extensively in distribution, but the scale of it is always small and belongs to microfracture. The compound fracture is the result of both tectonic movement and hydrocarbon forming process. The combination of above fractures in time and space forms the three dimension reservoir space network of mudstone, which satellites with abnormal pressure zone in plane distribution and relates to sedimentary faces, rock combination, organic content, structural evolution, and high pressure, etc.. In Zhanhua depression, the mudstone of third segment in shahejie formation corresponds with a set of seismic reflection with better continuous. When mudstone containing oil and gas of abnormal high pressure, the seismic waveform would change as a result of absorb of oil and gas to the high-frequency composition of seismic reflection, and decrease of seismic reflection frequency resulted from the breakage of mudstone structure. The author solved the problem of mudstone reservoir predicting to some degree through the use of coherent data analysis in Zhanhua depression. Numerical modeling of basin has been used to simulate the ancient liquid pressure field in Zhanhua depression, to quantitative analysis the main controlling factor (such as uncompaction, tectonic movement, hydrocarbon generation) to surpressure in mudstone. Combined with factual geologic information and references, we analyzed the characteristic of basin evolution and factors influence the pressure field, and employed numerical modeling of liquid pressure evolution in 1-D and 2-D section, modeled and analyzed the forming and evolution of pressure in plane for main position in different periods, and made a conclusion that the main factors for surpressure in studied area are tectonic movement, uncompaction and hydrocarbon generation process. In Zhanhua depression, the valid fracture zone in mudstone was mainly formed in the last stage of Dongying movement, the mudstone in the third segment of Shahejie formation turn into fastigium for oil generation and migration in Guantao stage, and oil and gas were preserved since the end of the stage. Tectonic movement was weak after oil and gas to be preserved, and such made for the preserve of oil and gas. The forming of fractured mudstone reservoir can be divided into four different stages, i.e. deposition of muddy oil source rock, draining off water by compacting to producing hydrocarbon, forming of valid fracture and collecting of oil, forming of fracture reservoir. Combined with other regional geologic information, we predicted four prior mudstone fracture reservoirs, which measured 18km2 in area and 1200 X 104t in geological reserves.