Trends of anthropogenic sources in a Southeastern Mediterranean coastal site over five years

Abstract

A five-year study of PM₁₀ concentrations was carried out from 2017 to 2021 in the port of a Mediterranean coastal city, with an annual collection rate approaching 50 % of the days. The chemical composition of the PM₁₀ dataset was analyzed to assess changes in both natural sources and the effects of regulations and mitigation measures on PM₁₀ and its precursors. While overall PM₁₀ concentrations remained stable over the study period, the analysis suggests that mitigation measures have contributed to a reduction in daily exceedances of PM₁₀ levels in the area.

Using positive matrix factorization, seven distinct PM₁₀ sources were identified and ranked by their contribution: road traffic, bulk materials + dust resuspension, aged sea salt, Saharan intrusion, fresh sea salt, shipping emissions, and ammonium sulphate. Further analysis showed decreasing trends over the five-year period for road traffic, shipping, and ammonium sulphate sources, and increasing trends for Saharan intrusion and aged sea salt sources. No significant trends were observed for the bulk materials + dust resuspension and fresh sea salt sources. Although the measures taken by the Port of Alicante did not lead to a reduction in the PM₁₀ average concentrations of this source, they did reduce the number of exceedance episodes. On the other hand, the efforts to reduce emissions from shipping and traffic succeeded in reducing the contribution of these sources.