Microbial corrosion on underwater pottery relics with typical biological condensation disease

Abstract Underwater pottery relics salvaged from shipwrecks are vulnerable to physical, chemical and biological corrosion. In this study, the microscopic morphology and structural composition of glazed pottery fragments excavated from the South China Sea as well as purple clay teapot samples from the Yangtze River Estuary II shipwreck were analyzed by means of optical microscopy, scanning electron microscope equipped with energy dispersive spectrometer, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier infrared transform spectroscopy and photoluminescence spectroscopy. According to the research results, the corrosion products deposited on the surface of the glazed pottery fragment from the South China Sea mainly included FeOOH and MnO2, whereas those on the surface of the purple clay teapot fragment from the Yangtze River Estuary II shipwreck primarily incorporated FeS2 and FeS. According to the corrosion phenomenon, it was speculated that the underwater pottery relics were mainly corroded by different microorganisms in the underwater environment, including manganese-oxidizing bacteria, dissimilatory metal-reducing bacteria and sulfate-reducing bacteria. As the corrosion process of these cultural artifacts was described and related models were established, this study provides valuable reference for the disease removal and protection of pottery relics.