Geochemical characterization of salts generated from bird droppings on historic heritage. The church of El Salvador (Ubeda, Jaen)

Damage on historic heritage caused by salts related to bird droppings should be properly identified and located. The best combination of methodologies in order to identify the source of such type of salts consist of: mapping surface conductivity of walls, extracting salts using cellulose poultices and evaluating solutions geochemistry. In this case study, we concluded that KNO3 was the predominant salt in those areas where salt efflorescence caused larger damage. Conversely, Na+, K+, NO3- and Cl- were predominant in areas where salts were at an early stage of crystallization. The correct identification of the origin of salts in walls enables efficient planning for intervention for cleaning and maintenance of heritage.