Source apportionment of inorganic ions in airborne urban particles from Coruña city (N.W. of Spain) using positive matrix factorization.

Water-soluble atmospheric particulate matter was analyzed for pH, conductivity and inorganic ions: Mg(2+), Ca(2+), K(+), Na(+), NH(4)(+), Cl(-), NO(3)(-) and SO(4)(2-) by ion-chromatography. In order to get a deeper insight on the atmospheric data and assess the 'optimal' number of pollution sources, principal component analysis and cluster analysis were applied. After that, the second objective was to apply a recently developed chemometric technique (positive matrix factorization) to perform source apportionment and get ion balances. Four pollution patterns were identified, namely, marine, industrial, urban and building-related source pollutants. Ion balances were also made in a straightforward manner.