A Study On Emergency Monitoring Methods Of VOCs In Environmental Pollution Accidents

There were many serious environmental pollution accidents taking place in China these years. It is therefore of great importance to develop emergency monitoring techniques for different accidents. This thesis covers the emergency monitoring of volatile organic compounds (VOCs). The thesis consists of 5 parts.The first one is a brief introduction of pollution accidents and the present situation of monitoring techniques. The analysis methods of VOCs in common use are also summarized in this part.The second part includes the study on sampling of VOCs. Summar canister is suitable for sampling of VOCs with boiling point between 30 and 220;Teflon bag is good for collecting the sample of VOCs with boiling point between 30 and 155 ; and Polyester bag is only appropriate for the sampling of VOCs with boiling point between 30 and 75 . In any case, the sample can be stored beyond 4days steadily with concentration retetion higher than 80%.The third part is a study on adsorbents. By comparing safely sampling volume of the different adsorbents, it is concluded that GDX serie adsorbents are better than Tenax and Carbotrap.The forth part is the research on the rapid quantitation of VOCs. This is facilitatedly multiplying the relative response of a target compound by its RRF measured at the same analysis condition. Data bases of RRF relative to a standard are set up for quantitation of 52 VOCs using J&W and RTX Volatiles capillary columns in use of internal and external standard method. And the standards used were benzene, methyl benzene and ethyl benzene. According to RRF, the organic compounds can be divided into aliphatichydrocarbon and aromatic hydrocarbon. Concentrations of other VOCs can be estimated by the average RRF value of compounds in the similar category, and the largest extent of error is -85.9%~57.7%.The fifth part is the application of the emergency monitoring method. P&T-GC-MS is a better technique for emergency monitoring of VOCs, it can analyze VOCs in air, water, and soil. Detection limits are between 0.07ug/L and 1.87ug/L(0.07~ 1.87p,g/kg for soil). The repeatability. (n=ll) varied between 2.67% and 14.2%. The recoveries of air samples ranged from 94.0% to 125%, water samples from 93.7% to 136%, and sediment samples from 87% to 127%.The concentrations and distribution of 52 VOCs were determined in sediments of the Fushan bay, using a modified P&T-GC-MS method. Low VOCs concentrations are found for most of the 45 sampling sites. However, in the north, east, southeast of the bay, significant amounts of BTEX were found. Although VOCs in sediments should, in general, not be regarded as a major problem in the marine environment of Fushan bay, high local concentrations may be a cause of concern.