Morphological and geochemical characterization of the particulate deposits and the black crust from the Triumphal Arch of Galerius in Thessaloniki, Greece: Implications for deterioration assessment

A Short Overview of Recent Developments in the Application of Polymeric Materials for the Conservation of Stone Cultural Heritage Elements

Stones are ones of the most ancient natural materials exploited by humans, with different uses, from tools to buildings, that have endured over time in better conditions than other objects belonging to cultural heritage. Given the importance of those silent witnesses of our past, as well as our duty to preserve all parts of cultural heritage for future generations, much effort was put into the development of materials for their consolidation, protection, self-cleaning, or restoration. Protection of ancient stone monuments and objects has gained the interest of researchers in the last decades in the field of conservation of cultural heritage. In this respect, the present paper aims to be a critical discussion regarding potential polymeric materials, which can be used in restorative and conservative approaches for stone materials of cultural heritage importance, against physical degradation phenomena. Recent advances in this area are presented, as well as the current bottle-necks and future development perspectives.

Study on the mechanism of the black crust formation on the ancient marble sculptures and the effect of pollution in Beijing area

In Beijing area, the precious stone objects often suffer from the black crusts on the specific parts of the objects, in order to understand the forming mechanism of the black crusts, samples from the stone sculptures in Beijing Stone Carving Art Museum, ZHIHUA Temple and Museum of Western Zhou Yandu Relics were taken and studied. Nondestructive measurement was carried out firstly to acquire main elements of the samples by portable X-ray spectrum (pXRF). Morphology and microstructure of typical black crust samples were examined by ultra-depth of field microscope (UDFM) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). Compositions of black crusts and body rocks were evaluated with X-ray diffraction (XRD), Raman spectra and mapping. Inductively coupled plasma optical emission spectrometry (ICP-OES) and pyrolysis-gas chromatography/mass spectrometry (Py-GCMS) were used to identify the major pollution sources leading to the black crusts.

Through this study, the composition of the black crusts was revealed. Different gypsum crystals and carbonaceous species were found. Pollutant elements analysis and pyrolysis products provide indicators of the pollution sources. As consequence of strong photochemical oxidation processes and the high temperature from June to September in Beijing, more acid rain precursors can be formed. Frequent sulphation process occurs on the CaCO₃/CaMg(CO₃)₂ surface. Combining morphology results and atmospheric data, the formation of black crusts in Beijing can be deduced.

Chemical Characterization of Particulate Matter in the Renaissance City of Ferrara

Atmospheric aerosols are today a key issue in air pollution, mostly related to public health. Two test areas in Ferrara, one in the city center (urban location) and one in the industrial area (industrial location), were studied in June–July 2016 using the SEM technique to identify the environmental impact of some potential pollutant sources. Collection was performed using adhesive tapes applied on the surface of road signs, which allows to select particulate matter moving on air with diffusion movement and to exclude the particles usually deposed by the gravitational process. Dimensional characterization has shown that, usually, smaller particles tend to aggregate themselves in bigger polycrystalline particles with the geometric diameter of up to 10 μm. Micro-analytical data have revealed a wide heterogeneous range of compositions: more abundant silicate followed by carbonate, chlorine, sulphate, carbon, and organic. This preliminary study has highlighted that the Renaissance city of Ferrara is affected by an environmental problem linked to the presence of particulate matter induced by industrial activities, as is the case with some of the most polluted cities in the world. The observations and analytical data pointed out the need for further investigation to better define the features of the fine particulate matter. This will be useful to preserve the cultural heritage of this Medieval-Renaissance city.