直接采样法确定面源恶臭挥发率的研究进展

确定面源恶臭挥发率的方法一般有两种:间接采样法和直接采样法.直接采样法由于具有许多优点而得到了广泛的应用.采样设备的选择会影响到恶臭样品的组成,通过对比可知,由动态采样器和静态采样器确定的恶臭挥发率的结果是不同的.用风洞法确定的恶臭挥发率与用问接法确定的恶臭挥发率有较好的一致性,可以作为恶臭扩散模型的输入参数.     

环境空气连续采样系统的改进

目前 ,很多环境监测站已采用 2 4ｈ连续采样监测代替了过去的季五日采样法。连续采样监测系统由空气自动连续采样器、总悬浮颗粒物 (ＴＳＰ)采样器和辅助风机 (主要是采样管道引风机和采样亭排气扇 )组成。空气连续采样器设有时控系统 ,可以根据要求随时启停 ,ＴＳＰ采样器无隔日采样控制系统 ,辅助风机则经常出现仪器停止采样后继续运转的情况。对此 ,今利用空气连续采样器的时控系统 ,增加一个ＣＪ1 0 - 5型交流接触器 ,实现了对采样系统所有设备的控制 ,使之都能按要求启停 ,从而节约了用电量 ,减少了风机的不必要运转。现采用的是ＨＢ -…     

主动采样法采集博物馆空气中微量污染气体

根据博物馆污染气体的种类,对气体主动采样法进行了采样器种类、吸收液种类和浓度、吸收液体积的选择。验证了气体采样流量、采样时间与气体采样浓度的线性关系,确定了酸性和碱性污染气体的主动采样方法,为监测文物保存环境污染气体提供了可行方法。     

用被动式采样器监测二氧化硫

二氧化硫的被动式采样法,几十年来经前人不断的研究,到目前为止,Scheeren等人选定了威廉氏采样器(也称为“徽章式”采样器),它是一个只有6 mm厚的环形容器,底上有涂渍过的石英滤片,用一个未涂渍的聚四氟乙烯滤片(也用聚苯乙烯环)固定,而聚四氟乙烯另一作用是防止由于湍流而产生的扩散过程和避免硫酸盐微粒的干扰。为了用于长周期暴露法采样,Palmas等人设计了聚苯乙烯管(以下称DS管),它的底部装有一     

扩散法采集个体接触空气中氨

本文采用扩散法将空气中氨采集在磷酸———甘油浸渍的无纺布吸收层上。该法采样速率为１３７６±８４ｍｌ／ｍｉｎ，与动力采样法现场对比测定，总不确定度为±１９３％，。采样器体积小，无噪声，操作方便，适于个体接触量与室内空气污染监测     

关于大气采样效率的含义、测定和应用

一、大气采样效率的提出:大气样品采样方法通常有三种:直接采样法、富集采样法和无动力采样法.第一种方法适合于大气中某污染物含量较高的测定,可直接以注射器、采气袋或采气管等进行采样;第三种方法则不需以任何动力,根据污染物的某些性质,使大气中的某污染物直接与试纸或采样用滤纸上某物质发生物理的或化学的反应,得到可供测定用的样品;第二种方法富集采样法,也称浓缩采样法,则适合于大气中某污染物含量较低的测定,用得较多的是溶液吸收法,其次是固体阻留法,而冷冻法则用得较少.不管对于哪种采样方法,都存在着     

一种淡水大型底栖无脊椎动物采样器研究

研制出一种长方体的十字筐采样器,在采样器内分别填装石、砂、底泥和水草4种基质,利用大型底栖无脊椎动物对生境的选择性进行样本被动采集。基质越多,采样器采集的生物种类越多,生物量也更丰富。用新研制的十字筐采样器和传统的篮式采样器对松花江流域7个采样点进行大型底栖无脊椎动物对比采样,结果显示:十字筐采样器是一种优良的采样器,适合在松花江流域乃至全国推广应用。     

大水量采样器,采样技术在环境监测中的应用

在环境监测工作中,采样是重要步骤,一些先进国家的环境保护机构对发展水中痕量污染物的富集采样技术极为重视,自动采样器(装置)得到广泛应用.美国国家环保局(EPA)下属的辛辛那提环境监测与支持实验室编著的《水与废水采样及样品保存手册》一书,专门介绍了一些自动采样器,认为自动采样器的使用为进行环境污染监测和筛选环境水样中的优先监测物和致突变物质,提供了方便,使过去因工作量大而无法广泛开展的工作成为可能.采样器以及采样技术的发展水平反映了一个国家环境监测水平.     

TSPM-1型大气总悬浮微粒采样器性能检测统计分析

TSPM1型大气总悬浮微粒采样器是一种与国际通用的大流量TSP采样器可比对,经久耐用,流量控制准确可靠且在采样时无需现场实测流量即可投入运行的新型TSP采样器。 一、与国际通用的大流量TSP采样器具有可比性是中流量TSP采样器作为环境监测中常规TSP采样器的前提条件。     

我国降水自动采样器的现状和发展趋势

我国降水自动采样器的现状、存在的问题和今后的发展趋势.     

Chemcatcher and DGT passive sampling devices for regulatory monitoring of trace metals in surface water

This work aimed to evaluate whether the performance of passive sampling devices in measuring time-weighted average (TWA) concentrations supports their application in regulatory monitoring of trace metals in surface waters, such as for the European Union's Water Framework Directive (WFD). The ability of the Chemcatcher and the diffusive gradient in thin film (DGT) device sampler to provide comparable TWA concentrations of Cd, Cu, Ni, Pb and Zn was tested through consecutive and overlapping deployments (7-28 days) in the River Meuse (The Netherlands). In order to evaluate the consistency of these TWA labile metal concentrations, these were assessed against total and filtered concentrations measured at relatively high frequencies by two teams using standard monitoring procedures, and metal species predicted by equilibrium speciation modeling using Visual MINTEQ. For Cd and Zn, the concentrations obtained with filtered water samples and the passive sampling devices were generally similar. The samplers consistently underestimated filtered concentrations of Cu and Ni, in agreement with their respective predicted speciation. For Pb, a small labile fraction was mainly responsible for low sampler accumulation and hence high measurement uncertainty. While only the high frequency of spot sampling procedures enabled the observation of higher Cd concentrations during the first 14 days, consecutive DGT deployments were able to detect it and provide a reasonable estimate of ambient concentrations. The range of concentrations measured by spot and passive sampling, for exposures up to 28 days, demonstrated that both modes of monitoring were equally reliable. Passive sampling provides information that cannot be obtained by a realistic spot sampling frequency and this may impact on the ability to detect trends and assess monitoring data against environmental quality standards when concentrations fluctuate.     

Bootstrapping to investigate the effect of number of macroinvertebrate samples on confidence limits of the mean

A resampling technique (bootstrapping) was used to evaluate the effects of increasing sample number on the confidence limits of mean density and the mean number of taxa (Families) in addition to the performance of four different sampling devices used to collect macroinvertebrates in three streams of contrasting anthropogenic impact. The four sampling devices were a Hess sampler, a modified Hess sampler equipped with an internal water pump, a Surber sampler, and a two-pole kick-net. In general, confidence limits decreased predictably as the number of samples increased, most notably with the addition of a third sample. The density of organisms captured with the Surber sampler was significantly lower than that of the Hess sampler but greater than that of the kick-net sampler. No significant difference in the number of Families was found among sampling devices. Based upon a minimal 10% reduction in confidence limits compared to the previous sample, a minimum of four replicates was suggested when using the Surber sampler. In general, other methods required a greater number of replicates that the Surber to adequately represent density, but this did not hold when applied to the number of taxa. Despite the inconvenience of having to bend down to use the Surber sampler, this study found no evidence to reject its apparent popularity as a sampling method for macroinvertebrates.     

被动采样在水体中有机污染监测的应用:以PAHs为例

半透膜采样技术是一种可原位、连续、动态监测水环境中非极性、弱极性有机污染物的被动采样技术,已在国内外发展20余年,但在环境监测中使用很少。从半透膜被动采样特点、采样器构造入手,着重对应用该技术的环节进行剖析,同时涉及被动采样结果及其评价方法。最后以多环芳烃（PAHs）为例,综述了近年来SPMD技术监控水体中非极性、弱极性有机污染物的常用分析技术及其发展。     

Effects of sampling techniques on physical parameters and concentrations of selected persistent organic pollutants in suspended matter

This study focusses on the effect of sampling techniques for suspended matter in stream water on subsequent particle-size distribution and concentrations of total organic carbon and selected persistent organic pollutants. The key questions are whether differences between the sampling techniques are due to the separation principle of the devices or due to the difference between time-proportional versus integral sampling. Several multivariate homogeneity tests were conducted on an extensive set of field-data that covers the period from 2002 to 2007, when up to three different sampling techniques were deployed in parallel at four monitoring stations of the River Rhine. The results indicate homogeneity for polychlorinated biphenyls, but significant effects due to the sampling techniques on particle-size, organic carbon and hexachlorobenzene. The effects can be amplified depending on the site characteristics of the monitoring stations.     

Sampling gaseous oxidation products of aromatic compounds in gas/particle separation systems

In this study we performed a direct comparison between two different ambient air samplers to characterize their performance in sampling oxidized gaseous organic compounds, known as oxidation products of aromatics. We investigated compounds with a variety of functional groups and vapor pressures. A polyurethane foam (PUF) adsorbent and an annular diffusion denuder sampler were operated along with particle filters. In both systems the sampling devices were liquid-extracted, followed by derivatization and analysis by GC-MS. The PUF system works very well for aromatic as well as non-aromatic compounds, whereas the denuder shows smaller collection efficiencies for highly volatile non-aromatic compounds. In addition, the sampling efficiencies in the PUF set-up are in good agreement with the calculated vapor pressures of the compounds and also the particle phase is not affected by most compounds.     

Development of an integrative passive sampler for the monitoring of organic water pollutants

The development of convenient and competitive devices and methods for monitoring of organic pollutants in the aquatic environment is of increasing interest. An integrative passive sampling system has been developed which consists of a solid poly(dimethylsiloxane) (PDMS) material (tube or rod), acting as hydrophobic organic receiving phase, enclosed in a water-filled or an air-filled low-density polyethylene (LDPE) membrane tubing. These samplers enable the direct analysis of the pollutants accumulated during exposure in the receiving phase by thermodesorption-GC/MS, avoiding expensive sample preparation and cleanups. The capabilities of these sampling devices were studied for the sampling of 20 persistent organic pollutants (chlorobenzenes, hexachlorocyclohexanes, p,p'-DDE, PAHs, and PCBs) in laboratory exposure experiments. For the three sampler designs investigated the uptake of all target analytes was integrative over exposure periods up to 9 days (except PCB 101). The determined sampling rates range from 4 to 1340 microl h(-1) for the water-filled samplers and from 20 to 6360 microl h(-1) for the air-filled ones, respectively. The sampling rate of the analytes is dependent on their molecular weight, partition between water and sampler media (PDMS, polyethylene, water, air) and also of the sampler design. The passive samplers enable the estimation of time-weighted average (TWA) concentration of water pollutants in the lower ng l(-1) to pg l(-1) range.     

The role of hydrodynamics, matrix and sampling duration in passive sampling of polar compounds with Empore SDB-RPS disks

There is an increasing need to monitor concentrations of polar organic contaminants in the aquatic environment. Integrative passive samplers can be used to assess time weighted average aqueous concentrations, provided calibration data are available and sampling rates are known. The sampling rate depends on environmental factors, such as temperature and water flow rate. Here we introduce an apparatus to investigate the sampling properties of passive samplers using river-like flow conditions and ambient environmental matrices: river water and treated sewage effluent. As a model sampler we selected Empore SDB-RPS disks in a Chemcatcher housing. The disks were exposed for 1 to 8 days at flow rates between 0.03 and 0.4 m s(-1). Samples were analysed using a bioassay for estrogenic activity and by LC-MS-MS target analysis of the pharmaceuticals sulfamethoxazole, carbamazepine and clarithromycin. In order to assess sampling rates of SDB disks, we also measured aqueous concentrations of the pharmaceuticals. Sampling rates increased with increasing flow rate and this relationship was not affected by the environmental matrix. However, SDB disks were only sampling in the integrative mode at low flow rates <0.1 m s(-1) and/or for short sampling times. The duration of linear uptake was particularly short for sulfamethoxazole (1 day) and longer for clarithromycin (5 days). At 0.03 m s(-1) and 12-14 degrees C, the sampling rate of SDB disks was 0.09 L day(-1) for clarithromycin, 0.14 L day(-1) for sulfamethoxazole and 0.25 L day(-1) for carbamazepine. The results show that under controlled conditions, SDB disks can be effectively used as passive sampling devices.     

Evaluation of the Chemcatcher and DGT passive samplers for monitoring metals with highly fluctuating water concentrations

Passive sampling devices accumulate chemicals continuously from water and can provide time weighted average (TWA) concentrations of pollutants over the exposure period. Hence, they offer a number of advantages over other conventional monitoring techniques such as spot or grab sampling. The diffusive gradient in thin film (DGT) and the Chemcatcher passive samplers can be used to provide TWA concentrations of labile metals, but the approaches to their calibration differ. DGT uses diffusion coefficients of metals in the hydrogel layer, whereas Chemcatcher uses metal specific uptake rates, with both sets of values obtained under controlled laboratory conditions with constant aqueous metal concentrations. However, little is known of how such samplers respond to fluctuating concentrations. We evaluated the responsiveness of these two passive sampling devices to rapidly changing concentrations of Cd, Cu, Ni, Pb and Zn in natural freshwater, over a relatively short deployment time. Maximum metal concentrations in water were varied between 70 and 140 microg L(-1). Experiments were carried out in a tank with a rotating carousel system and filled with Meuse river water, allowing a degree of control over experimental conditions while using natural river water. Fluctuating concentrations were obtained by stepwise addition of standard solutions of the metals. The reliability and accuracy of the TWA concentrations measured by the samplers were assessed by comparison with concentrations of the metals in spot samples of water taken regularly over the deployment period. The spot samples of water were either unfiltered (total), filtered (0.45 microm) or ultrafiltered (5 kDa). Predictive speciation modelling using the visual MINTEQ programme was also undertaken. There was reasonable agreement between the TWA concentrations of Cd and Ni obtained with Chemcatcher and DGT and the total Cd and Ni concentrations measured in repeated unfiltered spot samples. For elements (i.e. Cu, Pb, Zn) that associate to a significant degree with suspended solids, colloids or dissolved organic carbon, or form complexes with large organic ligands, optimum agreement was with the filtered or ultrafiltered fractions and with the predicted inorganic and inorganic-fulvic acid associated fractions. While Chemcatcher-based TWA concentration ranges for Cu and Zn were in best agreement with the total filtered fraction, there was lack of agreement for Pb. The combined use of DGT devices with open pore (OP) and restricted pore (RP) gels allowed the labile fraction of metal associated with large organic ligands or DOC to be differentiated and quantified, since this is available to DGT OP but unable to diffuse into the DGT RP. This evaluation of the two sampling devices clearly demonstrated their ability to react reliably to transient peaks in concentration of metal pollutants in water and indicated where future efforts are needed to improve calibration data. Such samplers may prove valuable in responding to the monitoring requirements of the European Union's Water Framework Directive.     

Porous silica spheres as indoor air pollutant scavengers

Porous silica spheres were investigated for their effectiveness in removing typical indoor air pollutants, such as aromatic and carbonyl-containing volatile organic compounds (VOCs), and compared to the commercially available polymer styrene-divinylbenzene (XAD-4). The silica spheres and the XAD-4 resin were coated on denuder sampling devices and their adsorption efficiencies for VOCs evaluated using an indoor air simulation chamber. Real indoor sampling was also undertaken to evaluate the affinity of the silica adsorbents for a variety of indoor VOCs. The silica sphere adsorbents were found to have a high affinity for polar carbonyls and found to be more efficient than the XAD-4 resin at adsorbing carbonyls in an indoor environment.