Insights into the mixing of particulate matter and aerosols from different sources in a Caribbean industrial town: composition and possible health effect

The mixture and interactions of different types of particulate matter (PM) derived from various sources lead to their physical and chemical transformations and change their level of impact on human health. For this reason, this study investigates the physical and chemical properties of PM derived from the interactions between different PM sources such as wildfires, geological sources, sea spray, and urban and industrial activities in the industrial town of Barranquilla, Atlántico, Caribbean region. Particles are composed of larger C-rich particles (soot/compacted soot), carbon allotropes, organics, C-rich coatings, and nanoparticles (NPs) of amorphous silica, silicates, salt minerals (mainly Na-sulfates), Fe-, Ti-, and Zn-oxides as well as Zn-bearing-phosphates and -sulfates. Some aggregates are chemically heterogeneous containing over ten different chemical elements including metals such as Cr and Pb. The occurrence of modified highly dense soot particles, the chemical heterogeneity, and the occurrence of nucleated salt and metal-oxides NPs as well as C-rich surface coatings on individual NPs indicate strong interactions between PM originating from different sources. The size range of the characterized PM (< 2.5 µm) indicates that the observed particles can enter the lung system. The biological activity of NPs or elements associated with these particles will then depend on their solubility, size, surface composition (i.e., C-rich coating), and the stability of the material in which they are embedded.