Assessment of marine and urban-industrial environmental impact on stone acting as the base of a quaternary bronze sculpture

[Display omitted] •The influence of atmospheric components deposition on the deterioration of a base of a bronze sculpture was demonstrated.•Salt formation showed a different morphology and composition depending on the orientation and the sheltered position.•Metal runoff occurrence was due to the dissolution of copper alloy caused by chemical reactivity with acidic atmosphere.•The concentration of sulfate, nitrate e fluoride were strictly related with industrial port area were the memorial is located. This work investigates the influence of a marine and urban-industrial environment on the deterioration of a funerary memorial in Getxo (Basque Country, Spain). The sculpture and artificial stone materials as well as their degradation products were characterised via a multi-analytical approach. An in situ characterisation of the bronze statue and its artificial limestone base was carried out with portable Energy Dispersive X-Ray Fluorescence (ED-XRF) and Raman spectrometers. In addition, several samples of white crusts as well as metal runoff crusts and biological patina were collected and some of them were prepared as cross-sections. High Resolution Micro-X-ray fluorescence and micro-Raman spectroscopy were used as non-destructive methods to detect original and degradation compounds. The test of soluble salts was also carried out on the samples and ion chromatography was employed in the laboratory. Exclusively calcite salt-efflorescences were found at the monument side with ED-XRF and Raman spectroscopy. While their morphology was compact at unsheltered sites, they showed a lamellar structure at sheltered locations, whose increased volume strongly influences the destruction of the memorial. The spectroscopic characterization of metal runoff showed that its excessive occurrence on the memorial surface was due to the dissolution of the copper-alloy caused by chemical reactivity with the surrounding acidic atmosphere. The formation of brochantite Cu4(SO4)(OH)6, posnjakite Cu4(SO4)(OH)6·(H2O), langite Cu4(SO4)(OH)6·2(H2O), or malachite Cu2(CO3)(OH)2 was favored exclusively in metal runoff crusts at unsheltered locations. However, much thinner crusts collected at sheltered sites showed a different composition, with copper species such as moolooite (Cu(C2O4)·nH2O) and atacamite Cu2Cl(OH)3. The soluble salt extraction showed a variable concentration of soluble ions depending on the area where the samples come from. The sample from north west sheltered location showe