Characterization of black crust on archaeological marble from the Library of Hadrian in Athens and inferences about contributing pollution sources
Dimitriοs Mitsos, V. Kantarelou, Eleni Palamara, A. G. Karydas, N. Zacharias, Evangelos Gerasopoulos
Abstract
Samples of black crust from the Roman-era monument of the Library of Hadrian (Athens) have been collected to perform chemical and mineralogical characterization of the degradation products on built heritage, utilizing a synergy of analytical techniques. The decay features consist of typical black crusts and a Fe-rich aluminosilicate patina. The chemical composition of the crusts, the element distribution along the crust and the characterization of individual embedded particles were combined to determine groups of elements related to specific sources and investigate how they are related to each other. Three main typologies of particles were identified: a) carbonaceous particles from diesel exhausts and domestic boilers, b) Si-rich particles from vehicular emissions and mineral dust, and c) metallic Ti-rich and Fe-rich particles from coal combustion and domestic heating, respectively. Traffic was found to pose a clear fingerprint on the type and chronological development of anthropogenic pollutant deposition in the black crusts formed in this particular urban environment.