低空分层降水和云水同步釆集系统的开发和应用

笔者自行开发并研制了低空(＜1 km)分层降水和云水采集系统,该系统成功地应用于福建省厦门市和贵州省贵阳市酸性降水来源和成因的研究中,取得了显著的成果,为探讨酸性降水来源和成因提供了有效的技术手段和支持。该系统可以在一定程度上代替航空测量,目前国内外的类似研究中没有使用该系统进行样品采集的先例,因此该系统的开发填补了国内外相关研究领域的空白。      

北京市25种公路绿化植物及配置模式的绿量

计量研究公路绿地的生态服务功能有助于科学评估公路绿化的无形价值。以北京市顺义区顺平路(S305)的绿化植物群落为研究对象,运用WinScanopy For Canopy Analysis冠层分析仪采集数据,研究了公路绿化常见植物及配置模式的绿量率,并建立了25种公路绿化常见植物的绿量率模型,以期为公路绿化树种选择和群落配置提供基础分析与参考。结果表明:阔叶乔木的绿量率在3.02~4.80之间,针叶乔木的绿量率集中在4~6之间,灌木植物的绿量率较小,种植紧凑的绿篱绿量率达到3.94;不同配置模式的群落绿量率大小顺序依次为:针阔混交林>阔叶林>针叶林>灌木群落。其研究结果为公路绿化建设和绿地生态效益的计量提供了科学依据。     

大气气溶胶中有机成分研究进展

有机物是大气气溶胶的重要组成部分,尤其是在细颗粒中,可占其干重的10%～70%。由于有机气溶胶的健康及气候效应,有机物的组成、源分布、颗粒行为等的研究越来越受到人们的重视。其中,有机物成分的鉴别和定量已成为近年来的研究热点。在分析中,就目前有机气溶胶的采样、有机成分提取、分离及定性、定量分析方法进行了综述,并比较了各种方法的优缺点。     

Effect of housing geometry on the performance of Chemcatcher passive sampler for the monitoring of hydrophobic organic pollutants in water

Passive sampling of pollutants in water has been gaining acceptance for environmental monitoring. Previously, an integrative passive sampler (the Chemcatcher) was developed and calibrated for the measurement of time weighted average concentrations of hydrophobic pollutants in water. Effects of physicochemical properties and environmental variables (water temperature and turbulence) on kinetic and thermodynamic parameters characterising the exchange of analytes between the sampler and water have been published. In this study, the effect of modification in sampler housing geometry on these calibration parameters was studied. The results obtained for polycyclic aromatic hydrocarbons show that reducing the depth of the cavity in the sampler body geometry increased the exchange kinetics by approximately twofold, whilst having no effect on the correlation between the uptake and offload kinetics of analytes. The use of performance reference compounds thus avoids the need for extensive re-calibration when the sampler body geometry is modified.     

A directional passive air sampler for monitoring polycyclic aromatic hydrocarbons (PAHs) in air mass

A passive air sampler was developed for collecting polycyclic aromatic hydrocarbons (PAHs) in air mass from various directions. The airflow velocity within the sampler was assessed for its responses to ambient wind speed and direction. The sampler was examined for trapped particles, evaluated quantitatively for influence of airflow velocity and temperature on PAH uptake, examined for PAH uptake kinetics, calibrated against active sampling, and finally tested in the field. The airflow volume passing the sampler was linearly proportional to ambient wind speed and sensitive to wind direction. The uptake rate for an individual PAH was a function of airflow velocity, temperature and the octanol-air partitioning coefficient of the PAH. For all PAHs with more than two rings, the passive sampler operated in a linear uptake phase for three weeks. Different PAH concentrations were obtained in air masses from different directions in the field test.     

Evaluation of ogawa passive sampling devices as an alternative measurement method for the nitrogen dioxide annual standard in El Paso, Texas

Nitrogen Dioxide (NO₂) is a common urban air pollutant that results from the combustion of fossil fuels. It causes serious human health effects, is a precursor to the formation of ground level ozone, another serious air pollutant, and is one of the six criteria air pollutants established by the United States (U.S.) Clean Air Act (CAA). Ogawa Passive Sampling Devices (PSDs) for NO₂ were collocated and operated at six NO₂ Federal Reference Method (FRM) monitor locations in the El Paso, Texas area for the 2004 calendar year. Passive samples were taken at 2-week, 3-week, and 4-week intervals and compared against the continuously operating FRM monitors. Results showed that the collective NO₂ annual arithmetic mean for all passive monitors was identical to the NO₂ mean for all FRM monitors. Of the individual locations, three passive annual NO₂ means were identical to their corresponding FRM means, and three passive annual NO₂ means differed from their corresponding FRM means by only one part per billion (ppb). Linear correlation analysis between all readings of the individual NO₂ PSDs and FRM values showed an average absolute difference of 1.2 ppb with an r ² of 0.95. Paired comparison between high and low concentration annual NO₂ sites, seasonal considerations, and interlab quality control comparisons all showed excellent results. The ease of deployment, reliability, and the cost-savings that can be realized with NO₂ PSDs could make them an attractive alternative to FRM monitors for screening purposes, and even possibly an equivalent method for annual NO₂ monitoring. More tests of the Ogawa NO₂ PSD are recommended for different ecosystem and climate regimes.     

Restricted adaptive cluster sampling

Adaptive cluster sampling can be a useful design for sampling rare and patchy populations. With this design the initial sample size is fixed but the size of the final sample (and total sampling effort) cannot be predicted prior to sampling. For some populations the final sample size can be quite variable depending on the level of patchiness. Restricted adaptive cluster sampling is a proposed modification where a limit is placed on the sample size prior to sampling and quadrats are selected sequentially for the initial sample size. As a result there is less variation in the final sample size and the total sampling effort can be predicted with some certainty, which is impor- tant for many ecological studies. Estimates of density are biased with the restricted design but under some circumstances the bias can be estimated well by bootstrapping. © Rapid Science 1998     

Combining mapped and statistical data in forest ecological inventory and monitoring – supplementing an existing system

A forest ecological inventory and monitoring system combining information derived from maps and samples is proposed based on ecosystem regions (Bailey, 1994). The system extends the design of the USDA Forest Service Region 6 Inventory and Monitoring System (R6IMS) in the Pacific Northwest of the United States. The key uses of the information are briefly discussed and expected results are illustrated with examples. The system is flexible, allowing regions based on ecological considerations to be modified. Sampling intensities that are affordable are likely to be insufficient to provide meaningful estimates for key parameters relating to rare and endangered species, watersheds, and other ecological units. Methods are proposed for collecting additional information in follow-up surveys and combining it with relevant information obtained in R6IMS. Near-continuous information on weather and possible pollution variables recorded by instruments at sampling sites is needed to develop meaningful models to understand what is happening in the ecoregions. R6IMS and the proposed additions constitute a dynamic system which will be modified further as data are analyzed.     

Seasonal and spatial occurrence and distribution of atmospheric polycyclic aromatic hydrocarbons (PAHs) in rural and urban areas of the North Chinese Plain

Passive air sampling (PAS) was employed to study the occurrence of gaseous and particle-bound PAHs in the North Chinese Plain. The averaged concentrations of gaseous and particle-bound PAHs were 485 ± 209 ng/m³ and 267 ± 161 ng/m³, respectively. The PAHs concentrations at urban sites were generally higher than those at rural ones with ratios <1.5 in spring, summer and fall, but differences between them were not significant for the wintertime and annually averaged concentrations. This urban-rural distribution pattern was related to the PAHs emission sources. PAHs spatial variation can be partially (49%) explained by emission with a simple linear regression method. Both the gaseous and particle-bound PAHs were highest in winter and lowest in summer, with winter/summer ratios of 1.8 and 8, respectively. Emission strength was the most important factor for the seasonality.