Effects of Burnings of Wax Apple Stubble and Rice Straw on Polychlorinated Dibenzo-p-Dioxin and Dibenzofuran Concentrations in Air and Soil

Abstract

Measurements of the concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were made in ambient air, ash, and soil impacted by the open burning of wax apple and rice straw residues. Measurements showed that the mean PCDD/F concentration (0.458 pg I-TEQ/Nm³; international toxicity equivalence) in air at two wax apple orchards during open burning increased markedly, ~8.1 times higher than that (0.057 pg I-TEQ/Nm³); before open burning. In addition, the mean PCDD/F concentration (0.409 pg I-TEQ/Nm³) in ambient air at a rice straw field was 4.6 times higher than that (0.089 pg I-TEQ/Nm³) before open burning. After burning the residues of wax apple stubble and rice straw, the contents of PCDD/F in ashes were 1.393 and 1.568 ng I-TEQ/kg-ash, respectively, and the contents of PCDD/F in soil were 2.258 and 2.890 ng I-TEQ/kg-soil, respectively. Therefore, the turnover of soil with the ash after open burning over years will result in the accumulation of PCDD/Fs in farm soils.