WSOC and Its Relationship with BC, Levoglucosan and Transition Metals in
the PM2.5 of an Urban Area in the Amazon

Water-soluble organic carbon (WSOC) makes up a large mass fraction of the organic carbon in
the aerosol and can influence important cloud processes in the atmosphere. The capacity of WSOC
to form metallic complexes with transition metals is well known; however, its influence on the
aerosol of urban areas in the Amazon region is not very well known. In this study, we investigated
the relationship between WSOC, black carbon (BC), levoglucosan (LEV) and transition metals
(Fe, Cu and Mn) present in the PM2.5 (particles with a diameter smaller than 2.5 µm) of an urban
environment during the dry season in the central Amazon. Oxalic acid (C2) was used to identify
the influence of transition metals on WSOC. The mean mass concentration value of the PM2.5 was
14.72 μg m-3 (2.11-31.68 μg m-3). The WSOC made up 58.34% of the PM2.5 mass, followed by
BC (20.28%), and LEV (2.62%). The WSOC showed significant correlation with the transition
metals analyzed (> 0.56), especially Mn with C2 (linear coefficient (R2
) = 0.74). A multiple linear
regression with WSOC, BC and LEV showed a strong linear correlation between them (R2
= 0.86),
indicating the influence of biomass burning and vehicle traffic on the organic aerosol.