Sensitivity of PM10 oxidative potential to aerosol chemical composition at a Mediterranean urban site: ascorbic acid versus dithiothreitol measurements

The oxidative potential (OP) of PM10 daily samples collected at a traffic site in southeastern Spain during summer and winter was assessed by two acellular assays: the ascorbic acid (AA) and dithiothreitol (DTT) methods. Although PM10 levels were similar during both periods, OP values (expressed in nmol min-1 m-3) showed a defined seasonal trend. The AA activity was higher in summer than in winter, whereas the DTT reactivity exhibited an opposite seasonal pattern. Both assays were sensitive to different PM10 components, as shown by the results of the linear correlation analysis. Moreover, the relationship between OP values and PM10 chemical species was not the same during summer and winter, indicating that particle toxicity is associated with different sources during the warm and cold seasons. When OP values were expressed on a mass basis (nmol min-1 µg-1), lower correlation coefficients with PM10 chemical species were generally obtained compared to volume-normalized activities. These outcomes suggest that only some specific components have a significant intrinsic oxidative potential.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11869-023-01332-1.

Quantification of the impact of port activities on PM10 levels at the port-city boundary of a mediterranean city

The main objective of this work was to quantify the impact of handling of bulk materials on PM₁₀ levels measured at the port-city border of Alicante (Spain), located on the western Mediterranean coast. To achieve that goal, 355 PM₁₀ samples were collected at the perimeter of the harbor of Alicante from March 2017 to February 2018. A 181 sample subgroup was chemically characterized in order to perform a source apportionment study with the EPA PMF 5.0 model. Eight factors were identified, two of them directly related to the handling of bulk materials (Limestone + gypsum and Clinker), accounting jointly for 35% of the average PM₁₀ concentration. A Road traffic factor was the second highest contributor to PM₁₀ levels (17%) while the Shipping emissions factor accounted for only 6% of the average PM₁₀ mass. Other factors such as Biomass burning+ secondary nitrate and Aged sea salt represented a joint contribution of 25% of the PM₁₀ mass. Results indicate that emission abatement strategies should primarily focus on the reduction of fugitive emissions caused by the handling of bulk materials at the docks. Moreover, scenarios including reductions of more than 50% in bulk handling sources and 10% in other anthropogenic sources would help to reduce anthropogenic exceedances of the daily PM₁₀ limit (50 μg·m^-3) and to approach to WHO daily PM₁₀ standard (20 μg m^-3).