Source Apportionment of Heavy Metals in Wet Deposition in a Typical Industry City Based on Multiple Models

Abstract

Handan city as a transportation hub in North China, air quality ranks at the bottom all year round, causing environmental pollution that has aroused widespread concern. In order to explore the pollution characteristics and main sources of heavy metals in atmospheric wet deposition in the city, and comparison of the applicability of multiple traceability models, a total of 76 wet deposition samples were collected in the three functional areas from December 2017 to November 2019 by a dry and wet deposition automatic sampler. Concentrations of Cu, Zn, Cr, Ni, Pb, and As were determined and enrichment factors were calculated. Sources of these heavy metals were apportioned by PMF, Unmix, and APCS-MLR models, and analyzed using a backward trajectory analysis model. The results showed that the concentrations of these heavy metals in the atmospheric wet deposition were in order of Zn, Cr, Pb, Cu, Ni, and As, and their mean concentrations were 29.53, 14.11, 9.18, 7.03, 6.41, and 1.21 μg·L−1, respectively. According to the results of EF, the studied heavy metals were mainly affected by anthropogenic activities. The source apportionment results showed that heavy metal pollution in the wet deposition was mainly affected by traffic sources, industrial sources, and coal combustion sources, and PMF identified an additional source factor: metal smelting source. By comparing the relevant parameters of the source apportionment results of the three models, the APCS-MLR model has better accuracy results than PMF and Unmix models. The analysis of the backward trajectory of the air mass showed that the wet deposition of Handan in the study time was mainly from the southwest direction, accounting for 54.35%. In the future, more evaluation methods and models will be used to compare and analyze the different application scenarios and parameter selection requirements in order to contribute to urban atmospheric environmental pollution prevention and control work.