Investigation on dioxin level and odor fingerprint in ambient air , leaf and soil in the vicinity of
ABSTRACT According to the dioxin concentrations of the sampling points (each incinerators has 8 sampling points) within 2-5 Km radius from the stack of this project’s three planned incinerators, all the measured dioxin concentrations are between 0.002 and 0.114 pg-TEQ/m3 which are similar to those of last year (0.010 ~ 0.071 pg-TEQ/m3, excluding samples while the incinerators were shut down). These concentrations are lower than the standard value, 0.6 pg-TEQ/m3 , in the air in Japan. The average dioxin concentrations of the soil samples are between 2.13 and 2.78 pg-TEQ/g d.w. . All these dioxin concentrations are within the range of background dioxin level in soils in urban area, except the sample of the first sampling time of the Taipei zoo with a higher concentration of 14.86 pg-TEQ/g d.w.. The current dioxin regulation in soils is <1000 pg-TEQ/g d.w., all the measured Dioxin concentrations in soils of this project are lower than this control standard. According to the results of different sampling times, only Pei-Tou has relatively significant difference with respect to the dioxin concentrations in the ambient air, the dioxin concentration in the downwind area is higher than that of the upwind one. It seems like the dioxin concentrations in soils are not affected by the direction of wind. As for the fingerprint characteristics of odor, the following compounds were detected in the air in most the sampling locations: toluene, xylene, 1-butanol, limonene and 2,4-dimethyl hexane. High concentrations of 2-propenylhydazone propanal and Octamethyl cyclotetrasiloxane were detected in the refuse dumping station of the Muzha incinerator in the first sampling time; however, these two compounds were not detected in the second sampling time. Among the odor material detected by odor meter, the limonene was present most often in these three incinerators; especially in the refuse bunker and refuse recycle station where the raw garbage are present. The results also show that the odor outside the plants is closly related to the wind direction and the pollution sources in that area. The research results of the past two years show the dioxin concentrations of all the incinerators are similar during the routine operation period; besides, no significant increasing or decreasing tendency for dioxin concentrations in upwind and downwind are found for both ambient air and soils. Therefore, it is suggested that the incinerators continue to use the current operating conditions and monitor the dioxin concentrations in the media around them. It will help us to understand the variation of the dioxin concentrations in the ambient air and reduce the doubt of environmental pollution and health for the residents. According to the survey results, the majority residents feel the odor resulting from the garbage combustion and the exhaust by the automobiles. More than 60% of the residents don’t have the experience of smelling of the odor. As for the odor problems caused by the incinerators, more than 60% of the residents think it’s necessary to increase the inspection and control of the odor emission inside the plants. The measured odor data show most of the odors come from refuse dumping station and ash bunker inside the plants. However, the characteristics of the odor outside the plants are different from those of inside the plants; they are caused by other emission sources. Since it’s a complicated analysis task to identify the sources of the odor materials, it’s also influenced by the weather conditions; therefore, it is suggested that the plants continue to investigate the locations with higher odor concentrations, the operating processes of the incinerators and the sources of the odor materials addressed by the residents, as well as to improve the management processes of the odor emission. Moreover, it is also suggested that the plants enhance the understanding of odor materials of the residents and the communications between two parties by proclaims.