PCDD/Fs in soil around a hospital waste incinerator： comparison after three years of operation

Polychlorinated dibenzo-p-dioxins and dibenzofurans （PCDD/Fs） can be formed during the cooling of flue gases in waste incinerator. These pollutants are either in the gas phase or attached to the fine particles, escaping dust collection. After stack emission, they are slowly oxidized photochemically （gas phase）, or eventually are deposited （dry and wet deposition of particulate） in earth surface. In 2007 and 2010, 11 soil samples were collected in the vicinity of a hospital waste incinerator （HWI）, prior and after its startup. In order to find out any variation of PCDD/Fs in soil, in brief dioxins, their concentrations were analyzed by high-resolution gas chromatography with high-resolution mass spectrometry （HRGC/HRMS）. Compared to the baseline survey （2007）, PCDD/Fs in soil significantly increased, by average, ＋81.6% in total PCDD/Fs and ＋132.7% in international toxic equivalency （I-TEQ） unit. By principal component analysis （PCA）, both the PCDD/Fs homologue and the HxCDF isomer profile in soil were found to become more similar with fly ash. Generally, this incinerator influences the soil only in a limited area. More comprehensive supervision, stricter management and more advanced technology should be implemented in this plant to reduce pollutants emission, even though the level of PCDD/Fs in soil is quite low at present.