Atmospheric particulate matter and historic buildings

Atmospheric particulate matter, along with gaseous and precipitation pollutants, were collected close to three historic buildings; Lincoln Cathedral, Bolsover Castle and Wells
Cathedral, in order to estimate the amount of sulphur and nitrogen deposited onto each. Results obtained showed that the gaseous dry deposition of both sulphur and nitrogen
was the main deposition pathway at Lincoln and Bolsover, whereas as a result of high precipitation amounts the wet deposition pathway was the most significant at Wells. At
each sampling site the amount of sulphur and nitrogen deposited as dry particulate matter was relatively insignificant.
Estimated washout values for both SO² and SO²⁻, indicated that the former provided approximately 80% of the sulphur in precipitation arriving at the building surfaces. The important role of the gas was reinforced by the significant correlation between the sulphur level in precipitation and sulphur dioxide. The concentration of sulphur in precipitation was found to decrease at high precipitation volumes, whereas the nitrogen
concentration was unaffected by precipitation volume.
A high sulphate to sulphur dioxide concentration ratio during the summer months was indicative of photochemical oxidation processes. Conversely, during the winter months
the relatively low sulphate to sulphur dioxide concentration ratio suggested that sulphate and sulphur dioxide were released from common sources.
Multivariate statistical techniques, comprising principal component analysis and multiple regression analysis, were used to infer characteristics about the origin of the constituent
parts of the collected particulate matter. In general, three sources of material; secondarily formed particulate matter, sea-salt and crustal material, were estimated to contribute to the collected particulate matter.