Abstract
Abstract. Nitro-monoaromatic hydrocarbons (NMAHs), such as nitrocatechols,
nitrophenols and nitrosalicylic acids, are important constituents of
atmospheric particulate matter (PM) water-soluble organic carbon (WSOC) and
humic-like substances (HULIS). Nitrated and oxygenated derivatives of
polycyclic aromatic hydrocarbons (NPAHs and OPAHs) are toxic and ubiquitous in
the ambient air; due to their light absorption properties, together with
NMAHs, they are part of aerosol brown carbon (BrC). We investigated the
winter concentrations of these substance classes in size-resolved PM from
two urban sites in central and southern Europe, i.e. Mainz (MZ), Germany, and
Thessaloniki (TK), Greece. The total concentration of 11 NMAHs (∑11NMAH concentrations) measured in PM10 and total PM were
0.51–8.38 and 12.1–72.1 ng m−3 at the MZ and TK sites, respectively, whereas
∑7OPAHs were 47–1636 and 858–4306 pg m−3, and ∑8NPAHs were ≤90 and 76–578 pg m−3, respectively. NMAHs
contributed 0.4 % and 1.8 % to the HULIS mass at MZ and TK, respectively.
The mass size distributions of the individual substances generally peaked in
the smallest or second smallest size fraction i.e. <0.49
or 0.49–0.95 µm. The mass median diameter (MMD) of NMAHs was 0.10 and 0.27 µm at MZ and TK, respectively, while the MMDs of
NPAHs and OPAHs were both 0.06 µm at MZ and 0.12 and 0.10 µm
at TK. Correlation analysis between NMAHs, NPAHs, and OPAHs from one side and
WSOC, HULIS, sulfate, and potassium from the other suggested that fresh
biomass burning (BB) and fossil fuel combustion emissions dominated at the TK
site, while aged air masses were predominant at the MZ site.