Odor-active volatile organic compounds along the seafront of Thessaloniki, Greece. Implications for sources of nuisance odor

Abstract

Volatile organic compounds (VOCs) have long been associated with odor nuisance at urban sites close to emission sources. Sulfur containing volatile organic compounds (VOSCs) in particular, constitute a major category of malodorous compounds since some of them are characterized by intense odor and low odor thresholds. VOSCs have both, anthropogenic and biogenic sources. The purpose of this study was to assess the concentration levels of a variety of VOCs (mercaptans, sulfides, thiophenes, aromatics and aldehydes) along the seafront of the city of Thessaloniki, northern Greece, a city with frequent citizen complaints for nuisance odor. 1-Hour sampling on adsorption tubes was carried out concurrently at 3 sites along the seafront of the city (EAST, CENTER and WEST) three times during the day in winter and summer 2020. VOCs analysis, performed on a Thermal Desorption - Gas Chromatography/Mass Spectroscopy (TD-GC/MS) system. Diurnal and seasonal variations, and correlations with prevailing meteorological conditions were investigated. Concentrations found along the seafront were compared to previous data from inner-city sites affected by urban and/or industrial activities. Most VOCs were found at lower concentrations at the seafront in comparison to inner-city sites demonstrating better air quality. Typical biogenically-deriving VOSCs such as carbonyl sulfide and dimethyl sulfide were found at the seafront either at higher or at similar levels with inner city thus suggesting negligible contribution from biogenic sources. Odor activity values were further calculated and assessed. Odor nuisance at all seafront sites was significantly higher in winter, being in both seasons maximum at the WEST seafront that is closer to port activities, polluted creek estuaries and industrial facilities. Mercaptans were identified as the major contributors to odor pollution followed by aldehydes. The new findings described in this study might contribute to the better understanding of the odor pollution from VOCs at coastal urban sites.

Keywords: Aldehydes; BTEX; Mercaptans; Sulfides; Thiophenes; VOCs.