Physical and Chemical Composition of Particulate Pollutants in an Urban Area of Cardiff, Wales

Abstract

The issue of particulate matter (PM) and associated health and environmental problems has been subjected to extensive research in a number of countries. However, there are no recent studies concerning the physical and chemical properties of PM from urban Cardiff. Measurements were made to study particulate matter, their sources, chemical compositions, gaseous precursors and their seasonal variations in urban Cardiff (latitude: 51° 28´ 59.47¨N and longitude: 03° 09´ 58.08¨W) from December 2009 to November 2010. A low volume air sampler for PM10 and PM2.5 particles, and real-time air samplers for TSP, PM10, PM2.5, PM1, NO, NO2, NOx, SO2 and VOCs were used during sampling. The collected ambient air suspended particles were analysed for seven major ions (Cl−, NO3−, SO42−, Ca²⁺, Mg²⁺, K⁺ and Na⁺) and 12 elements (Na, Mg, Al, K, Ca, Cr, Fe, Ni, Cu, Zn, Cd and Pb) by using an ion chromatography and atomic absorption spectrometer respectively. Cl⁻, SO42− and NO3− were generally the major ions in fractions of PM10 and PM2.5, while the elements Na, Mg, Ca, Al, K, and Fe were the most abundant elements. A good correlation was observed between PM10 and PM2.5 indicating that PM10 and PM2.5 contribute significantly to PM levels in urban Cardiff. Most of the ions and elements in both PM fractions were abundant in the winter season. Natural sources were the highest contributors followed by anthropogenic sources for the analysed elements in PM10 and PM2.5. Enrichment factor (EF) analysis showed the enrichment factor was higher in PM10 and PM2.5 elements such as Zn, Pb, Cu, Cr and Cd. The high enrichment factor of these elements in urban Cardiff suggested that the dominant sources for these elements were non-crustal. Real-time measurements of PM precursor gases did not exceed the standard concentrations given by the Air Quality Strategy (AQS) for these pollutants.