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61.
Givelet N Le Roux G Cheburkin A Chen B Frank J Goodsite ME Kempter H Krachler M Noernberg T Rausch N Rheinberger S Roos-Barraclough F Sapkota A Scholz C Shotyk W 《Journal of environmental monitoring : JEM》2004,6(5):481-492
For detailed reconstructions of atmospheric metal deposition using peat cores from bogs, a comprehensive protocol for working with peat cores is proposed. The first step is to locate and determine suitable sampling sites in accordance with the principal goal of the study, the period of time of interest and the precision required. Using the state of the art procedures and field equipment, peat cores are collected in such a way as to provide high quality records for paleoenvironmental study. Pertinent field observations gathered during the fieldwork are recorded in a field report. Cores are kept frozen at -18 degree C until they can be prepared in the laboratory. Frozen peat cores are precisely cut into 1 cm slices using a stainless steel band saw with stainless steel blades. The outside edges of each slice are removed using a titanium knife to avoid any possible contamination which might have occurred during the sampling and handling stage. Each slice is split, with one-half kept frozen for future studies (archived), and the other half further subdivided for physical, chemical, and mineralogical analyses. Physical parameters such as ash and water contents, the bulk density and the degree of decomposition of the peat are determined using established methods. A subsample is dried overnight at 105 degree C in a drying oven and milled in a centrifugal mill with titanium sieve. Prior to any expensive and time consuming chemical procedures and analyses, the resulting powdered samples, after manual homogenisation, are measured for more than twenty-two major and trace elements using non-destructive X-Ray fluorescence (XRF) methods. This approach provides lots of valuable geochemical data which documents the natural geochemical processes which occur in the peat profiles and their possible effect on the trace metal profiles. The development, evaluation and use of peat cores from bogs as archives of high-resolution records of atmospheric deposition of mineral dust and trace elements have led to the development of many analytical procedures which now permit the measurement of a wide range of elements in peat samples such as lead and lead isotope ratios, mercury, arsenic, antimony, silver, molybdenum, thorium, uranium, rare earth elements. Radiometric methods (the carbon bomb pulse of (14)C, (210)Pb and conventional (14)C dating) are combined to allow reliable age-depth models to be reconstructed for each peat profile. 相似文献
62.
Development and validation of methods for environmental monitoring of cyclophosphamide in workplaces
Methods to monitor contamination of workplaces with antineoplastic drugs have been developed and validated. Cyclophosphamide (CP) was used as a model compound as it is one of the most commonly used antineoplastic drugs. A wipe sampling method to detect contamination with CP at surfaces was developed. A personal air sampling method to sample gas and vapour on solid sorbent tubes and particles with filters was also developed. Wipe and filter samples were extracted and sorbent samples were eluted, all with ethyl acetate. The samples were analysed with liquid chromatography tandem mass spectrometry. (2)H(6)-labelled cyclophosphamide was used as an internal standard. The between-day precision was 2-5% for wipe samples, 4-6% for sorbent samples and 3-8% for filter samples. The limit of detection was 0.02 ng CP per sample for the wipe and filter methods and 0.03 ng CP per sample for the solid sorbent method. Wipe sampling on surfaces made of different materials resulted in mean recoveries between 78-106%. The desorption recovery was between 97-102% for the wipe samples, 97% for the sorbent samples and 101% for the filter samples. Samples were stable for up to 2 months at 5 degrees C and -20 degrees C and for about 2 d at room temperature. The developed methods were applied to the measurement of contamination with CP in a hospital pharmacy. Trace amounts of CP, 1.3 and 1.4 ng, were detected on surfaces in the pharmacy. 相似文献
63.
Degradation of Pesticides on Plant Surfaces and its Prediction - A Case Study on Tea Plant 总被引:4,自引:0,他引:4
The degradative kinetics of pesticides on plant surface are characterized by an initial rapid degradation which follows a first-order kinetics, then transferred to a more slower degradative rate. The degradative process mainly consists of photodegradation, evaporation, rainfall elution and growth dilution. The influencing parameters of these processes were investigated by using the tea plant as a case study. The predictive model of the initial concentration, photodegradation rate constant, evaporation rate constant, rainfall elution rate, growth dilution rate and the total degradation rate was discussed and verified in four locations situated in the range of 25°-30°N latitude, and acceptable results were obtained. 相似文献
64.
Thin-film technique is becoming an industry standard for the preparation of TiO2-based photocatalyst for organic destruction. The catalyst provides several advantages over the conventional powder TiO2 in the treatment of wastewater and groundwater. In this study, a continuous stir flow reactor model is developed capable of describing the photocatalytic process. The model incorporates the following fundamental mechanisms: adsorption, diffusion, liquid-film transfer, UV attenuation, and photocatalytic reaction. All of the simulation results indicate that there exists a highly nonlinear relation between each of these parameters and the destruction rate. Various incident light intensities also are incorporated to simulate the energy efficiency. The simulations illustrate that the photocatalytic model can be used to elucidate the effect of process variables. It is also possible to “custom-design” a catalyst for the treatment of a particular waste stream. 相似文献
65.
Advances in polymerase chain reaction (PCR) have permitted accurate, rapid and quantitative identification of microorganisms in pure cultures regardless of viability or culturability. In this study, a simple sample processing method was investigated for rapid identification and quantification of fungal spores from dust samples using both conventional and real-time PCR. The proposed method was evaluated for susceptibility to interference from environmental dust samples. Stachybotrys chartarum and Aspergillus fumigatus were used as test organisms. The sensitivity of detection in pure culture was 0.1 spore DNA equivalents per PCR reaction corresponding to 20 spores ml(-1) in the sample. However, 1 spore DNA equivalent per PCR reaction corresponding to 200 spores ml(-1) in the sample was the lowest amount of spores tested without interference in dust samples spiked with spores of either fungal species. The extent of inhibition was calculated using conventional and real-time PCR reactions containing fungal spores, specific primers, specific probes (for real-time PCR) and various amounts of dust. The results indicate that the extent of inhibition by dust on PCR varies with the type and amount of dust, and number of spores. No interference in the analysis of spiked samples was detected from 0.2 mg ml(-1) of four real-life dust samples at p-value >0.05 using 2 x 10(4) spores for conventional PCR and 2 x 10(5) spores for real-time PCR. However, samples containing >0.2 mg ml(-1) real-life dust compromised the PCR assay. These results suggest the potential usefulness of a simple sample processing method in conjunction with PCR for monitoring the fungal content of aerosols collected from indoor environments. 相似文献
66.
中国土壤中溴,碘的背景含量 总被引:1,自引:0,他引:1
通过对全国八百余个表层土样的分析测试,获得了中国土壤中溴、碘背景含量的总体水平及在各土类中的含量,相对于地壳丰度,中国土壤中溴、碘普遍得到了富集,溴、碘含量分异变化较大,并具有明显的地域分异特征,影响中国土壤中溴、碘含量的主要因素是降水量、土壤吸附体的含量以及某些特殊母质。 相似文献
67.
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69.
IntroductionHeavymetalsinwaterbodiesaresignificantlydifferentfromorganicpollutantsthatcanbemicrobiologicallydegradedordecomposed .Generally ,theyarepurifiedthroughtheiradsorptionontosuspendedsubstratesinrivers.Adsorptionofheavymetalsonriversuspendedsub… 相似文献
70.
CHEN Wen-ying 《环境科学学报(英文版)》2003,15(4):541-547
Emission projection and marginal abatement cost curves (MACs) are the central components of any assessment of future carbonmarket, such as CDM (clean development mechanism) potentials, carbon quota price etc. However, they are products of very complex,dynamic systems driven by forces like population growth, economic development, resource endowments, technology progress and so on. The modeling approaches for emission projection and MACs evaluation were summarized, and some major models and their results were compared.Accordingly, reduction and cost requirements to achieve the Kyoto target were estimated. It is concluded that Annex I Parties‘ total reduction requirements range from 503--1304 MtC with USA participation and decrease significantly to 140--612 MtC after USA‘ s withdrawal. Total costs vary from 21--77 BUSD with USA and from 5--36 BUSD without USA if only domestic reduction actions are taken. The costs would sharply reduce while considering the three flexible mechanisms defined in the Kyoto Protocol with domestic actions‘ share in the all mitigation strategies drons to only 0--16%. 相似文献