PCDD/Fs characteristics in flue gas and surrounding environment of iron and steel smelting industry.

Abstract

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) concentrations and distributions, emission factors and amounts, and ambient air and soil potential sources were investigated by collecting flue gas, ambient air, and soil samples from ten sintering furnaces and two electric arc furnaces of eight iron and steel smelting industries (ISSI) in China. In flue gas, the concentrations of PCDD/Fs ranged from 0.05 to 2.93ng I-TEQ Nm-3 (mass, from 0.38 to 30.67ngNm-3), with an average of 0.42ng I-TEQ Nm-3 (mass, 4.99ngNm-3), respectively. In ambient air, the concentrations ranged from 0.05 to 0.35pg I-TEQ m-3 (mass, from 0.66 to 5.66pgm-3), with an average of 0.20pg I-TEQ m-3 (mass, 2.96pgm-3), respectively. In surface soil, the concentrations ranged from 1.80 to 21.02ng I-TEQ kg-1 (mass, from 34.29 to 836.00ngkg-1), with an average of 5.82ng I-TEQ kg-1 (mass, 252.10ngkg-1), respectively. In deep soil, the concentrations ranged from 1.17 to 12.00ng I-TEQ kg-1 (mass, from 56.83 to 1488.00ngkg-1), with an average of 7.76ng I-TEQ kg-1 (mass, 433.20ngkg-1), respectively. Compared with emission limits for PCDD/Fs, the compliance was 78.9% in flue gas, 100% in ambient air, and 77.3% in soil. In congener profiles, the contributions of PCDFs were much higher than those of PCDDs in flue gas and ambient air, but the opposite was observed in soil. In ten sintering furnaces, the emission factors ranged from 22.11 to 901.22ng I-TEQ t-1, with an average of 373.80ng I-TEQ t-1, respectively. In two electric arc furnaces, the emission factors were 1667.52 and 894.96ng I-TEQ t-1, with an average of 1281.24ng I-TEQ t-1. According to both principal component analysis and hierarchical cluster analysis, all ambient air samples were affected by the emissions of PCDD/Fs from ISSIs, but to different degrees. However, the concentrations of PCDD/Fs in most soil samples were not influenced by the ISSI emissions.