Airborne particulate matter around the Cathedral of Burgos (Castilla y Leon, Spain)

A methodology to collect and analyse atmospheric particulate matter has bee n developed at the Cathedral of Burgos (Spain). Particles were collected in a portable particle sampler on carbon layers and stone surfaces. The analy ses were undertaken under SEM-EDX by means X-ray mapping and Featurescan (a program for the automated characterisation of particles). To determine the ir possible sources, particles collected in the sampler and on carbon layer s were classified according to their composition, mainly by cluster analysi s. Then, they were compared with those deposited on stone surfaces. This cl assification is useful when a plan of preventive conservation for monuments is to be undertaken. In general, no important differences are observed bet ween the chemical composition of particles directly collected from the atmo sphere and those deposited on different substrates. Fine particles present the highest sulphur contents (almost 100%), while calcium is the major elem ent in the medium and coarse particles. Other abundant elements are silicon , chlorine and phosphorus. The number of iron-rich particles is small. The study of the material deposited on carbon layers and stone substrates has c onfirmed the presence of gypsum in all cases. (C) 2000 Elsevier Science Ltd . All rights reserved.