Characteristics of water-soluble ions in condensable particulate matter emitted from stationary sources in Wuhan

Abstract

This study investigated the concentration and characterization of condensable particulate matter (CPM) and filterable particulate matter (FPM) emitted from different stationary sources in Wuhan. The concentrations of FPM and CPM were measured based on USEPA Method 202 and the water-soluble ions in particulate matter were analyzed using ion chromatography. The micro-morphological characteristics of the CPM were detected with scanning electron microscopy (SEM) techniques. The CPM concentrations for coal-fired plant A (Stack#1), coal-fired plant B (Stack#2), sintering plant (Stack#3), incineration plant (Stack#4), cement plant (Stack#5), glass plant (Stack#6) and biomass combustion plant (Stack#7) were 20.30 ± 1.51, 26.00 ± 1.53, 28.68 ± 1.15, 6.82 ± 0.55, 5.41 ± 1.59, 8.49 ± 0.76 and 25.50 ± 1.50 mg/Nm3, which were much higher than the corresponding FPM values except for Stack#3. These results indicate that different types of stationary sources in Wuhan do emit some CPMs. The CPMs collected from wet flue gas desulfurization (WFGD) plants were much higher than semi-dry flue gas desulfurization (SDFGD) plants. Moreover, SO42−, Cl−, NH4+ and NO3− were the major water-soluble ions in the CPM, which accounted for more than 90% of the total ions. These major ions could be mainly transformed from their gaseous precursors of SOX, HCl, NH3 and NOX, respectively. Na+ was more likely to form solid particles and was collected in the CPM filter, while SO42− was more likely to be collected in the impringer in the form of dissolved particulate matter.