热解吸/GC/MS联用测定石化工业区大气环境中挥发性有机物

采用二次热解吸／气相色谱／质谱联用测定石化工业区大气环境中挥发性有机物,质谱检测器同时进行全扫描和选择离子扫描,全扫描定性,选择离子扫描和内标法定量。方法线性良好,50种目标化合物的检出限为0.14ng-2.45ng,在3个浓度水平的加标回收试验中,1,1-二氯乙烯和二氯甲烷回收率较低,氯仿和苯低浓度回收率较差,其余46种目标化合物的回收率为83.4％-116％,RSD为0.5％-8.9％。     

膜萃取邻甲酚废水的传质特性研究

构造了卷绕式及管束式两种膜组件,采用均质硅橡胶膜,以氢氧化钠溶液为萃取液来萃取邻甲酚废水.通过考察邻甲酚初始浓度、两相流动状态、两相压差(△P)和温度等因素对传质过程的影响,研究了邻甲酚废水的膜萃取过程与机制.结果表明,初始质量浓度为21.93 g/L的邻甲酚废水很适合直接进行膜萃取;当△P<0.07 MPa时,总传质系数(Kov)随△P的增大而略有减小.当△P>0.07 MPa时,Kov随△P增大而显著增大,由实验数据拟合得到总的膜萃取传质模型.且该模型的实验值与理论值的相对误差在5%以内,满足工业设计要求.     

Street canyon ventilation and atmospheric turbulence

Operational models for pollutant dispersion in urban areas require an estimate of the turbulent transfer between the street canyons and the overlying atmospheric flow. To date, the mechanisms that govern this process remain poorly understood. We have studied the mass exchange between a street canyon and the atmospheric flow above it by means of wind tunnel experiments. Fluid velocities were measured with a Particle Image Velocimetry system and passive scalar concentrations were measured using a Flame Ionisation Detector. The mass-transfer velocity between the canyon and the external flow has been estimated by measuring the cavity wash-out time. A two-box model, used to estimate the transfer velocity for varying dynamical conditions of the external flow, has been used to interpret the experimental data. This study sheds new light on the mechanisms which drive the ventilation of a street canyon and illustrates the influence of the external turbulence on the transfer process.     

黔中白云岩风化剖面微量元素的地球化学特征

本研究是为了探讨微量元素在化学风化作用下的迁移特征及分布规律并讨论碳酸盐岩地区红色风化壳的物源问题。我们选择了贵州省遵义市新浦镇的一处发育完好的原生白云岩上覆红土剖面作为研究的对象。以Zr作为不活化元素,我们得到以下的认识:1)该白云岩上覆红土剖面是原地形成的淋滤剖面,微量元素的迁移系数在红土剖面中的变化都具有很好的规律性。元素对Nb-Ta、Zr-Hf和Y-Yb的相关性很强,其可以作为上覆土层物质非多来源的证据,而单一物源与下伏岩石高度相关,那么可以推断所研究的土壤来源于下覆碳酸盐岩的风化。2)在整个剖面中,大部分微量元素在风化过程中都表现出富集的特性,尤其在岩-土界面处达到最大化,这显示出了风化淋滤的过程。Nb、Ta、V和Hf是相对不活化的元素。3)轻稀土元素在岩土界面的富集系数是大于重稀土元素的,这表明轻稀土元素在淋滤过程中更易于迁移。此外,铁质壳对相关微量元素有着富集的作用。总之,本次的研究结果对探讨喀斯特地区红土型风化壳的物质来源问题有着重要的指示意义。     

Chemical composition and size distribution of secondary organic aerosolformed from the photooxidation of isoprene

Photooxidation of isoprene leads to the formation of secondary organic aerosol (SOA). In this study, the chemical composition ofSOA formed from OH-initiated photooxidation of isoprene has been investigated with gas chromatography/mass spectrometry (GC/MS)and a home-made aerosol time-of-flight mass spectrometer. Sampling particles generated in a home-made smog chamber. The sizedistribution of SOA particles was detected by a TSI 3321 aerodynamic particle size spectrometer in real time. Results showed thatSOA created by isoprene photooxidation was predominantly in the form of fine particles, which have diameters less than 2.5 m. Theobtained mass spectra of individual particles show that products of the OH-initiated oxidation of isoprene contain methyl vinyl ketone,methacrolein, formaldehyde, and some other hydroxycarbonyls. The possible reaction mechanisms leading to these products were alsodiscussed.     

Root studies on grass species in a semi-arid South Africa along a degradation gradient

Understanding changes in hydrological characteristics of rangeland ecosystems with degradation is essential when making rangeland management decisions in arid and semi-arid areas to ensure sustainable animal production. The impact of rangeland degradation on root production, root/shoot ratio and water-use efficiency was therefore determined for a semi-arid rangeland, over a 7-year period (1999/00 to 2005/06 growing seasons).Water-use efficiency (WUE) is defined as the quantity of above- and/or belowground phytomass produced over a certain period of time per unit of water evapotranspired. Sampling was from rangeland artificially maintained in three different rangeland conditions, viz. good, moderate and poor.As much as 86, 89 and 94% of the roots for rangelands in good, moderate and poor conditions, respectively, occurred at a depth of less than 300 mm. Root mass was strongly seasonal with the most active growth taking place during March and April. Root mass appears to be greater than aboveground phytomass for this semi-arid area, with an increase in roots in relation to aboveground phytomass production with rangeland degradation. The mean monthly root/shoot ratios for rangelands in good, moderate and poor conditions were 1.16, 1.11 and 1.37, respectively. Rangeland degradation significantly lowered above- and belowground phytomass production as well as the water-use efficiency. The mean WUE (root production included) were 4.79, 3.54 and 2.47 kg ha⁻¹ mm⁻¹ for rangelands in good, moderate and poor conditions, respectively. These water-use efficiency observations are among the few also including root production in its calculation. As a proportion of annual phytomass, litter fall of 7.17, 4.64 and 3.41% was obtained for rangelands in good, moderate and poor conditions, respectively. Increasing rangeland degradation increased the replacement of total root system by about 10 months and decomposition time of litter by 6 months.The importance of a well-established root system for sustainable production in the semi-arid rangelands cannot be overemphasized.     

HPLC分离-氢化物发生-动态反应池-ICP/MS联用分析废水中砷形态

采用高效液相色谱（HPLC）分离水中不同的砷物种,将串联进入氢化物发生(HG)-动态反应池（DRC）-电感耦合等离子体质谱仪(HPLC-HG-ICP-DRC-MS)系统进行检测,由此建立了废水中砷形态的分析方法,并探讨了最佳测试条件,最后对宁波部分地区废水中砷形态分布规律进行了初步探讨.结果表明,以0.04 mol·L-1L半胱氨酸(L-cys)、0.132 mol·L-1NaBH4和体积分数2%的HCl作为氢化物发生器载液,以H2作为DRC-ICP-MS反应气,控制流速为1.5mL·min-1时,4种As物种都有最佳的氢化物发生效率,且其它金属离子对分析干扰可忽略不计,求得As(Ⅲ)、As(Ⅴ)、单甲基砷（MMA）、双甲基砷（DMA）的检测下限（3倍噪音）分别为0.003、0.001、0.002、0.004 μg·L-1.此系统可成功测定废水中砷的形态.     

膜基吸收恶臭气体H2S的实验研究

选甲基二乙醇胺溶液为吸收剂,聚丙烯中空纤维膜作接触器,通过单因素实验研究膜基吸收恶臭气体H2S的影响因素。结果表明,吸收剂浓度对脱硫率影响明显,适当的吸收剂浓度是保证脱硫率的关键因素;进气速率增大可以提高传质系数、增强传质,但脱硫率降低;提高进气压力可以提高脱硫率,但不如吸收剂浓度影响大;吸收剂循环使用对脱硫率影响较大,应在满足出气要求的前提下,合理控制循环次数和循环比例。对含H2S347mg/m3的进气,实验得到的适宜的脱硫条件为:进气流速0.35m3/h、压力0.1MPa,吸收剂流量0.40m3/h、浓度3mol/L。在该条件下,单级膜组件脱硫率稳定在96%以上。     

气相色谱-三重四极杆质谱法测定水中持久性有机氯污染物

建立了液液萃取一气相色谱三重四极杆质谱多反应监测同时测定水中16种持久性有机氯污染物的方法,考察了不同萃取剂不同体积对有机氯萃取效率的影响,确定了16种持久性有机氯化合物多反应监测模式（MRM）的最佳质谱条件。方法检出限为0.33 ~ 0.65 ng/L,以纯水为基体,加入16种不同浓度水平的持久性有机氯化合物作回收试验,测得回收率在80.2% ~ 103.6%之间,测定的相对标准偏差4.0% ~11.5%（n=7）。     

Relationship between EMR and dissipated energy of coal rock mass during cyclic loading process

Dynamic collapses of deeply mined coal rocks are severe threats to miners. In order to predict the collapses more accurately using electromagnetic radiation (EMR), this paper researched the energy conversion mechanism in the damage process of coal rock mass, analysed its EMR and dissipated energy, and a relationship between which was established using the voltage amplitude of EMR signal and hysteresis loop generated in the loading and unloading cycles as a bridge; then a series of cyclic loading experiments using coal samples of Junde and Xinlu coal mines from Heilongjiang province were carried out, and EMR signal released during these cycles were collected. Results show that during a whole damage process of a sample, the cumulative values of EMR energy and corresponding dissipated energy (hysteresis loop area) well subject to the form of y=aln(x)+b, whose correlation coefficients are above 0.90, and EMR signals received by different frequency antenna seldom impacted on this relationship; the total EMR energy released from the whole failure process of the samples obtained from adjacent sampling point in same mining area are different to some extent, so are the dissipated energy; compared with cyclic loading for coal rock mass orderly with the peak loads of 5 kN and 10 kN previously, the dissipated energy of direct using that of 15 kN increase 17.8%, and EMR signal is more abundant; EMR energy received in each cycle increase steadily with the improvement of load level, and in a single loading and unloading cycle, sometimes it is very rich in the unloading phase, even more than the loading one.