Sources of humic-like substances in the Pearl River Delta, China: positive matrix factorization analysis of PM<sup>2.5</sup> major components and source markers

Abstract

Abstract. Humic-like substances (HULIS), the hydrophobic part of water-soluble organic carbon (WSOC), account for a significant fraction of PM 2.5 mass. Their source studies are so far largely qualitative. In this study, HULIS and WSOC were determined in 100 PM 2.5 samples collected in 2009 at an urban site (Guangzhou) and a suburban site (Nansha) in the Pearl River Delta in South China. The annual average concentration of HULIS was 4.83 and 4.71 µg m −3 , constituting 8.5 and 10.2 % of the PM 2.5 mass, while HULIS-C (the carbon component of HULIS) contributed 48 and 57 % of WSOC at the two sites, respectively. HULIS were found to correlate with biomass burning (BB) tracers (i.e., levoglucosan and K) and secondary species (e.g., SO 2− 4 and NH + 4 ), suggesting its association with BB emissions and secondary formation processes. Sources of HULIS were investigated using positive matrix factorization analysis of PM 2.5 chemical composition data, including major components and source markers. In addition to secondary formation process and BB emissions, residual oil combustion related to shipping was identified for the first time as a significant source of HULIS. Secondary formation process contributed the most, accounting for 49-82 % of ambient HULIS at the two sites in different seasons. BB emissions contributed a seasonal average of 8-28 %, with more contributions observed in the winter months (November-February) due to crop residue burning during harvest season. Residual oil combustion was revealed to be an important source at the suburban site in summer (44 % of HULIS-C) due to its proximity to one of the ports and the shipping lane in the region. Vehicle emissions were found to contribute little to HULIS, but had contributions to the hydrophilic WSOC fraction. The contrast in contributions from different combustion sources to HULIS and hydrophilic WSOC suggests that primary sources of HULIS are linked to inefficient combustion. This source analysis suggests further study of HULIS be focused on secondary formation process and source characteristics of HULIS from BB and residual oil combustion.

Nonpolar organic compounds as PM2.5 source tracers: Investigation of their sources and degradation in the Pearl River Delta, China

“…DG (22°57′ 44.85″N, 113°44′39.36″E) is on a small hill (foothill of about 10 m) in the grounds of a sprawling botanical garden surrounded by scattered urban towns (~6 km). NS (22°45′08.90″N, 113°36′09.17″E) is located on top of a five-story building (~20 m agl) in Nansha Information Technology Park in Nansha District, south of Guangzhou urban areas and~15 km north of a shipping port [Kuang et al, 2015]. Journal of Geophysical Research: Atmospheres 10.1002/2016JD025315 PM 2.5 samples were collected at each site once every 6 days from 2011 to 2012, except for two intensive sampling periods, one in mid-November to December 2011 at NS and the other in mid-July to mid-August 2012 at GZ and NS, which sampled once every 2 days.…”

Inter-comparison of NIOSH and IMPROVE protocols for OC and EC determination: implications for inter-protocol data conversion

“…(14), sugars -which include levoglucosan, mannosan, and galactosan -are used as a tracer to derive SWSOC based on the primary ratio (5.28, Fig. S22) obtained from a biomass burning source profile measured in the PRD region (Lin et al, 2010). The relationship between SWSOC and SOC is examined in Fig.…”

Exploration of PM<sub>2.5</sub> sources on the regional scale in the Pearl River Delta based on ME-2 modeling

“…Kuang et al (2015) also found that ship emissions could be a major source of secondary sulfate in the PRD in summer. HS and MDS had significantly higher concentrations than their upwind site, DM, suggesting that the area between MDS and HS could be a high-SO 2 -emission area, which is consistent with the fact that this area is an intensive industrial area.…”