Short review on PM-bound water. Its presence in the atmosphere, forms of occurrence and determination by Karl Fischer coulometric titration

Abstract

Literature data indicate, that the conversion of secondary PM (particulate matter) precursors are largely controlled by the amount of atmospheric water vapor, and that higher capacity of water accumulation is demonstrated mainly by fine particles of anthropogenic origin, rich in ionic compounds like sulfates, nitrates, ammonia and chlorides, arising for example from biomass incineration processes. Smaller retention capability is however typical for coarse PM particles of natural origin, containing lot of crustal material like aluminosilicates. It is therefore suspect that both – the size of PM particles and the source of its origin will determine its hygroscopicity. The quantitative and qualitative measurements of water contributions in PM for example by means of Karl Fischer titration method could be therefore a good marker of PM origin. Due to analytical limitations the identification of water contents in PM and the differences in water fingerprint between PM collected in different locations is still quite challenging.