超声萃取-高效液相色谱法测定土壤中苯并[a]芘研究

采用超声萃取-高效液相色谱荧光检测法对土壤中苯并[a]芘含量进行定性、定量分析.土壤样品用正己烷/二氯甲烷(1+1)超声萃取,萃取液经硅胶柱或佛罗里硅土柱净化浓缩定容,乙腈-水为流动相,线性梯度洗脱,流速为1.0 mL/min,荧光检测器激发波长为280 nm,发射波长为420 nm,外标法峰面积定量.结果显示:该方法检出限低,苯并[a]芘的检出限为0.15μg/kg.这种方法具有很好的精密度,相对标准偏差为3.9%~8.4%.实际水样加标回收率范围在72.5%~85.8%.能够满足土壤的监测要求.     

循环流化床烟气悬浮脱硫技术中试及机理分析

设计了新的循环流化床烟气悬浮脱硫中试装置,其烟气处理量达3500m³/h.首先进行了进料钙硫比(Ca/S)、过饱和温度对装置脱硫效率影响实验,进一步研究了脱硫塔内固体颗粒物循环和烟气流速等因素对脱硫装置性能的影响.对比实验研究表明:在Ca/S=1.2时,固体颗粒物的循环使系统脱硫效率提高15% 左右;脱硫塔内烟气设计流速可以偏高一些.本文同时对系统脱硫过程进行了机理分析,指出了延长脱硫剂有效停留时间的途径.     

Predator odour and its impact on male fertility and reproduction in Phodopus campbelli hamsters

 This study investigated the influence of cat urine odour in suppressing development and fertility in Campbell's hamster males. Exposure to this odour from postnatal day 11 until day 45 (sexual maturation) resulted in reduced sex organ weights, reduced testosterone levels and in an increase in abnormalities of the synaptonemal complex in both sex chromosomes and autosomes. Subsequent breeding experiments revealed a significant decrease in litter size. All these data indicate a severe effect of predator odour on the breeding success of potential prey species. It is assumed that these effects are caused by the sulphurous compounds in the urine; however, the underlying mechanisms are not yet known. Received: 31 January 2000 / Accepted in revised form: 6 June 2000     

CaH_2对Cu-Ce-La-ZSM-5催化分解NO性能的影响

实验采用一步离子交换法制备Cu-Ce-La-ZSM-5催化剂,然后采用共混法制得Cu-Ce-La-ZSM-5/CaH2催化剂。采用扫描电镜(SEM),电感耦合等离子体发射光谱(ICP-AES),X射线衍射(XRD),红外(FTIR)以及NO吸脱附(NO-TPD)对催化剂进行表征。结果显示CaH2的加入使得催化剂中铜离子存在形式发生变化,催化剂表面变光滑洁净,并且吸附NO能力增强。NO催化分解实验的结果表明CaH2提高了催化剂活性和抗氧性。CaH2助催性是由于其受热分解过程中产生的H2能将Cu2+还原为具有催化活性的Cu+,同时使催化剂表面洁净光滑更容易吸附NO。     

Estimation of mass transport parameters of gases for quantifying CH4 oxidation in landfill soil covers

Methane (CH(4)), which is one of the most abundant anthropogenic greenhouse gases, is produced from landfills. CH(4) is biologically oxidized to carbon dioxide, which has a lower global warming potential than methane, when it passes through a cover soil. In order to quantify the amount of CH(4) oxidized in a landfill cover soil, a soil column test, a diffusion cell test, and a mathematical model analysis were carried out. In the column test, maximum oxidation rates of CH(4) (V(max)) showed higher values in the upper part of the column than those in the lower part caused by the penetration of O(2) from the top. The organic matter content in the upper area was also higher due to the active microbial growth. The dispersion analysis results for O(2) and CH(4) in the column are counter-intuitive. As the upward flow rate of the landfill gas increased, the dispersion coefficient of CH(4) slightly increased, possibly due to the effect of mechanical dispersion. On the other hand, as the upward flow rate of the landfill gas increased, the dispersion coefficient of O(2) decreased. It is possible that the diffusion of gases in porous media is influenced by the counter-directional flow rate. Further analysis of other gases in the column, N(2) and CO(2), may be required to support this hypothesis, but in this paper we propose the possibility that the simulations using the diffusion coefficient of O(2) under the natural condition may overestimate the penetration of O(2) into the soil cover layer and consequently overestimate the oxidation of CH(4).