Identification and apportionment of local and long-range sources of PM<inf>2.5</inf> in two East-Mediterranean sites

Abstract

The East Mediterranean and Middle East (EMME) region is a global climate hotspot that suffers from a lack of robust environmental data. This region, especially the Middle East, lacks source apportionment studies that help determine the different contributions of common regional airborne particulate matter sources. This work focuses on two sites in the East Mediterranean, that are, Zouk Mikael and Fiaa, Lebanon. The study shows the comprehensive chemical characterization of PM2.5 samples collected over almost one year at two sites, serving as the source apportionment model, positive matrix factorization. Different sources were identified due to the integration of organic markers such as biogenic emissions, cooking, biomass burning, and diesel generators. Crustal dust and ammonium sulfate sources were the major contributors to PM2.5 (43% and 46% at Zouk and Fiaa, respectively). Through cluster analysis, the former originated from the Arabian and Saharan Deserts, while the latter had different local and distant origins (industrial zones of Europe and Turkey), in addition to the contribution of Arabian and African countries to carbonaceous matter concentrations through refinery emissions. Meanwhile, local anthropogenic sources contributed to 36% at both sites, excluding ammonium sulfate. Traffic and industrial emissions, including energy production, contributed more to Zouk (27%) than Fiaa (13%). Site-specific sources were also identified, with open waste burning at Fiaa contributing 16% and diesel generators at Zouk contributing 5%. Biogenic emissions contributed to 9–13%. These results will be important to policymakers to improve air quality in the EMME region while considering the potency of the PM in a region where the world health organization guidelines cannot be reached.