Pollutant fluxes onto the façades of a historical monument

Dry and wet deposition of ionic trace substances and total carbon to the walls of a historical monument (Salem Abbey, Germany) was determined based on periodical collection of rain water samples and washing solutions from cumulative collectors (surrogate surfaces). It is estimated that only a small fraction, ca. 1.5–3% of the precipitation and 10% of the pollutants deposition (to a horizontal receptor area) reached the (vertical) collectors (at 3 m above ground). With only one quarter of the pollutants wet deposited, dry deposition to the building was more important. Hereby, the building was a source of particulate material itself (sodium salts, CaCO3). While the fluxes of dry deposited pollutants to the individual façades differed only little from each other (with a preference to East), the wet deposited fractions differed widely due to a pronounced preference of precipitation from West. Large fluxes of total carbon (C/S = 9) were obviously not primarily related to carbonate stone weathering but to airborne carbonaceous material. It is concluded that the building is susceptible to stone decay in the forms of granular disintegration, dark encrustation and other as resulting from a combination of both physical factors (humid environment, the buildings orientation towards the sun and prevailing weather) and chemical factors (dry and wet depositional fluxes of pollutants, albeit at moderate concentrations).