A three-year investigation of metals in the atmospheric wet deposition of a basin region, north China: Pollution characteristics and source apportionment

Abstract

Precipitation samples were collected in Taiyuan, China, from January 2013 to December 2015. Thirteen elements were detected by inductively coupled plasma-mass spectrometry (ICP-MS). The total concentration of soluble and insoluble materials averaged 9695.26 μg L−1. Si was the most abundant element, accounting for 94.61% of the total, followed by Al and Fe. The wet deposition flux of the 13 elements was 3065.14 mg m−2·yr−1, with the highest flux detected in the summer and the lowest in the spring. The order of deposition flux was as follows: Si > Al > Fe > Zn > Ba > Cu > Mn > Cr > Sr > Pb > Ni > As > Cd. The elements mainly consisted of insoluble materials and accounted for 56.1–98.5% of the total. Per the enrichment factor (EF) results, Zn, Cu, Pb, As, and Cd were derived mainly from anthropogenic activities, while Al and Fe were derived mainly from crustal dusts. Positive Matrix Factorization (PMF) was used to identify 4 sources of soluble materials in 2015. Results revealed that industrial activities were the leading source, contributing to 50.47% of the total, followed by coal combustion (26.09%), vehicle emissions (13.59%), and dusts (9.85%). Combined with 3 years of back trajectory data, southeasterly air masses (with a proportion of 39%) were the main direction from which the precipitation in Taiyuan originated and had a considerable influence on pH and flux.