Search Results (63)

Natural carbonate stones such as limestones and marbles are widely used in heritage and contemporary architecture, yet their durability is increasingly threatened by wildfire-related thermal stress. Since water transport plays a key role in stone deterioration, understanding how high temperatures affect hydric behavior is critical for conservation. This study investigates thirteen Portuguese carbonate lithotypes (including marbles, limestones, a travertine, and a breccia) exposed to temperatures of 300 °C and 600 °C. Capillary absorption and open porosity were measured, alongside Leeb hardness (HL) and ultrasonic pulse velocity (UPV), to evaluate their predictive capacity for post-fire moisture behavior. Results show that thermal exposure increases porosity and capillary uptake while reducing mechanical cohesion. Strong correlations between UPV and hydric parameters across temperature ranges highlight its reliability as a non-invasive diagnostic tool. HL performed well in compact stones but was less consistent in porous or heterogeneous lithologies. The findings support the use of NDT tests, like UPV and HL, for rapid post-fire assessments and emphasize the need for lithology-specific conservation strategies. Full article

Around the world, a large number of stone artifacts have been exposed to air for long periods of time, showing multiple types of deterioration that have attracted widespread attention. Among them, there is an often overlooked deterioration of stone artifacts, i.e., black stains on the surface of the calcareous stone, which are tightly bonded to the substrate as a result of the long-term deposition of air pollution. However, due to the current lack of a clear understanding of the black stains, people often tend to use the wrong cleaning and conservation methods, which is not conducive to sustainable conservation. Therefore, there is an urgent need to comprehensively recognize the black stains in terms of material properties and environmental sustainability to guide scientific sustainable conservation methods. To this end, in this paper, we take the black stains observed on marble buildings in the Xianling Tomb, China, as an example, and for the first time, we aim to create a comprehensive understanding of black deposition from the aspects of material properties and environmental characteristics. Multi-analytical approaches, including polarized light microscopy, X-ray fluorescence (XRF), and scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDS), were employed to discern the differences between the substrate and black stains. The results revealed that the formation of black stains was attributed to prolonged exposure to various air pollutants (PM, SO₂, NO₂, CO, and O₃). Subsequently, observational data from 2015 to 2023 were utilized to investigate the temporal evolution of local air pollutants and their coupled resonances. Multi-scale variations (annual, seasonal, monthly, weekly, and daily) of pollutant concentration sequences were identified, which helps us to have a clearer perception and to proactively control air pollutants in the region from different cycles. In addition, wavelet coherence (WTC) demonstrated significant time-scale dependency in correlation with air pollutants, which provides effective data support for the coordinated control of air pollutants. This study reveals the mechanism of black stain deterioration on stone artifact surfaces, provides data support for the control and prediction of air pollutants oriented to the sustainable conservation of stone artifacts, and provides a novel and comprehensive approach to the scientific knowledge and sustainable conservation of stone artifacts. Full article

A diagnostic chemical analysis has been performed on a Roman Cippus funebris in precious white marble located close to an ancient Roman road. The Cippus was in good condition but almost completely covered by a black patina, requiring a conservative cleaning intervention. The restorer in charge of the restoration asked us to make a preliminary diagnosis, on the basis of which we could suggest the most appropriate intervention. The Cippus was dedicated to the young Quintus Cornelius Proclianus, who died at the age of 15, by his mother Valeria Calpurnia Scopele. It perfectly fits into the Roman funerary liturgy and also shows an Etruscan-type iconography that seems to confirm the Etruscan Gens of the family and its dating to the 1st century AD. Ion chromatography (IC) analyses were performed to determine anions and cations on solutions obtained from the extraction of salts from the four samples of the Cippus. pH, conductivity, and red-ox potential measures, as well as UV-visible spectra were carried out on the same solutions. A small fragment, spontaneously fallen from the Cippus’ surface, was also observed by optical microscopy (OM) and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). From the analyses, the dark patina that covered the surface before cleaning turned out to be made of black crusts, that is, smog particles adsorbed on sulfates, but above all, by a layer of microflora. The results allowed us to suggest some conservative interventions. Full article

Despite increasing conservation efforts for shorebirds, there are widespread declines in many shorebird species in North America. Climate change is causing significant shorebird range shifts and population declines. This study investigates the relationship between meteorological variability and shorebird population dynamics over ten years (2014–2023) at Fish Haul Beach, Hilton Head Island, South Carolina, USA. Shorebirds, reliant on specific habitats for breeding and foraging, are increasingly vulnerable to climate-driven changes, including shifts in temperature, precipitation, and wind speed. Using Generalized Additive Models with Poisson distribution, we analyzed species-specific count data for 12 shorebird species in relation to annual meteorological variables. Additionally, the Mann–Kendall test and Sen’s slope were employed to assess decadal trends in population counts. The results reveal significant declines in Black-bellied Plover (Pluvialis squatarola), Marbled Godwit (Limosa fedoa), and Willet (Tringa semipalmata). In contrast, Semipalmated Plover (Charadrius semipalmatus) and Piping Plover (Charadrius melodus) showed increasing trends, indicating potential habitat benefits or conservation success. Temperature emerged as a key driver affecting the abundance of several species, while precipitation and wind speed also played crucial roles in shaping population dynamics. Our findings underscore the sensitivity of shorebird populations to weather fluctuations, emphasizing the need for integrating meteorological variability into management strategies to ensure shorebird conservation. This study provides critical insights into the impacts of meteorological variables on migratory shorebird populations along the Atlantic Flyway. It highlights the importance of maintaining healthy coastal ecosystems in South Carolina. Full article

This work illustrates the results of an archaeometric investigation performed on 29 stone tesserae collected from 2021 to 2024 during the restoration campaigns of three mosaic floors at Praedia Iuliae Felicis in Pompeii (Campania, Italy). The tesserae were studied through a micro-analytical approach using Polarized Optical Microscopy (POM), Scanning Electron Microscopy (SEM) with Energy-Dispersive X-ray Spectroscopy (EDS) and Electron Probe Micro-Analyzer with Wavelength-Dispersive Spectroscopy (EPMA-WDS). The aim of the study was to determine the petro-chemical features of the mosaic tesserae and to obtain information about the provenance of the raw materials. The research highlights the use of different types of stone, such as volcanic and sedimentary, of probable local provenance. A single marble tessera was also recognized. In addition, the archaeometric study allowed a better knowledge of the executive technique and contributed to orienting the technical choices of the restoration. Indeed, a complementary study of conservation state of the three mosaic floors was conducted with the aim of better defining strategies for conservation and restoration, paying attention to the compatibility and to the interaction of the restoration products with the characteristics of the raw materials. Full article

Outdoor stone relics, including inscriptions, statues, temple grottoes, etc., are continuously subjected to natural weathering and air pollutants. Those made of marbles and other carbonate rocks are particularly vulnerable to acid rains, which can be protected by acid-resistant coatings. A novel method to prepare enamel-like hydroxyapatite coating on marble surfaces is presented in this paper and analyzed using optical microscopy, a scanning electronic microscope, grazing incident X-ray diffraction, and nano-indentation. The described coating is composed of tightly arranged hydroxyapatite nanorods, perpendicular to the marble substrate, with a thickness of 3–5 μm. Not only does the coating exhibit high acid resistance, it also has considerably higher elastic modulus and hardness compared to that synthesized by the well-known diammonium phosphate (DAP) method owing to the wellarranged microstructure. Consequently, the enamel-like hydroxyapatite coating would probably be more effective and durable for marble protection than the existing calcium phosphate coating. Full article

A marble processing plant (MPP) can achieve sustainable development by implementing energy-saving and consumption-reduction technology. Reducing energy loss in such an energy-intensive plant is crucial for overall energy savings. This study establishes an MPP optimization model based on the second law of thermodynamics and the law of conservation of mass. Marble is an aesthetically pleasing and long-lasting building material that has boosted economies in European and sub-Saharan African nations. However, high energy costs and scarcity have constrained the industry’s economic potential and hindered the achievement of optimal levels of production. The second law of thermodynamics is adopted to study the irreversibilities, inefficiencies, and exergetic performance of a marble processing plant. The Aspen Plus commercial software application is used to model and generate thermodynamic data, determine energy flow streams and conduct sensitivity and optimization analysis to improve data quality and energetic performance outcomes. From the results, the various scales of the exergetic destruction, efficiencies, and exergetic losses are determined, and recommendations are established. The overall energy and exergy efficiency levels were determined to be 87.43% and 86.84%, respectively, with a total exergetic destruction of 200.61 kW. The reported methodologies, cutting-edge ideas, and solutions will give industrialists and other significant stakeholders in the global manufacturing sector cutting-edge information about energy usage and ways to cut energy losses in both new and existing factory designs, manage energy cost components, and adjust energy efficiency to maximize productivity. Full article

In recent years, attention has been paid to finding eco-friendly products that could represent an alternative for the chemicals usually used during conservation procedures. In the field of the devitalization of biological patinas, the most studied products are essential oils (EOs). Several works tested EOs in vitro on microorganisms isolated from stone artifacts but few applied these products on real artworks colonized by a complex patina. In the present work, the biocidal effect of two EOs (cinnamon bark and oregano) and two EO-based products (Biotersus and Essenzio) was compared to that of three chemical biocides commonly used in the conservation of stone artifacts (Biotin R1+R2, NewDes50, and Preventol RI50). The products were applied by brush in situ on a marble slab characterized by a green patina. The biocidal activity was evaluated by analyzing the chlorophyll fluorescence and quantifying ATP through biochemical tests. Furthermore, the products’ interference with stone was evaluated by colorimetric measures on sedimentary rock samples. The results indicate that chemical biocides exhibited biocidal activity of greater than 99.5% with a single application, while cinnamon oil (at a 1% concentration) and Essenzio required two applications to achieve the same level of efficacy. Conversely, oregano oil and Biotersus were not able to effectively reduce microorganism vitality, even with repeated applications. Full article

Calcareous stones, such as marble and limestone, have been widely used in ancient architecture due to their durability, abundance, and ease of extraction and workability. However, their chemical nature renders them vulnerable to atmospheric pollutants. With industrialization and socio-economic growth, air pollution has severely impacted built heritage, including numerous historical buildings and monuments, particularly under changing climate and environmental conditions. Various forms of degradation, such as acid corrosion, mineral crystallization, and black crusts, are widespread and typically driven by atmospheric pollutants like sulfur dioxide (SO₂), nitrogen oxides (NO_X), ozone (O₃), and particulates (PM), which accelerate the deterioration of stone surfaces. To develop sustainable mitigation strategies, it is essential to gain an in-depth understanding of these deterioration mechanisms and current technological advancements. This paper first reviews the influencing factors and underlying mechanisms of atmospheric deterioration of calcareous stones. Subsequently, it discusses the advantages and limitations of traditional and advanced conservation and restoration techniques at the micro-level, as well as pollution management strategies that can be adopted. Finally, the challenges of research in this field are highlighted, and directions for the sustainable conservation of calcareous stones are proposed. Full article

This work aimed to assess the potential efficacy of a novel polysaccharides-based extract as a green consolidant for the pictorial layer on marble substrates. Understanding its properties could lead to determining whether it can ensure the correct conservation and transmission of the cultural heritage. Four different types of marble specimens were prepared with paint based on malachite (egg, tempera grassa, rabbit glue, and linseed oil as binders). Colorimetric analyses, peeling tests, SEM-EDS, and FTIR spectroscopy were used to test the properties of the consolidant. Results reveal that no aesthetic changes occur when using the extract on painted surfaces and that the cohesive properties of most pictorial films increase after its application, confirming the consolidating effect. In conclusion, the use of an innovative green product for the restoration of marble-painted surfaces can be considered a possible good solution for consolidating treatment. Through this initial explorative research, we suggest an innovative approach to the protection of cultural heritage that doesn’t cause harm to both the restorer’s health and the environment. Full article

Currently, one of the most important challenges for the conservation of stone artworks is the removal of metal corrosion products on their surfaces. Traditional cleaning methods, which typically involve the application of aqueous solutions containing chelating agents capable of complexing these metal ions, have shown some weaknesses. These weaknesses become apparent when such methods are applied to statues and other vertical surfaces or when aiming to limit the cleaning process to a specific area with controlled application times. Furthermore, the porosity of the stone surface plays a role concerning the cleaning efficiency. To address these issues, chelating agents can be incorporated into gel-like materials. This study is a proof of concept to evaluate the cleaning efficacy of various gel formulations composed of polyvinyl alcohol (PVA), borax (B), and agarose (AG), loaded with two chelators: ethylenediaminetetraacetic acid (EDTA) and potassium sodium tartrate (PST or Rochelle salt). Three types of carbonate stones (travertine, Lecce stone, and Carrara marble) characterized by different porosities were artificially stained with copper sulphates and treated with the different PVA-B-AG formulations. The effectiveness of the treatment was directly monitored on the stones using a multi-technique approach that included scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and non-invasive portable nuclear magnetic resonance (NMR). Additionally, the rheological properties of the gels were investigated, and the Fourier transform infrared attenuated total reflection spectroscopy (FTIR ATR) was used to analyse the chemical structure of the gel before and after treatment, aiming to understand the changes induced by the cleaning process. Full article

The Kaladawan iron deposit is located in the North Altyn Tagh and exhibits occurrences of iron ore bodies at the contact zone between Ordovician magmatic rocks (basalts, rhyolite, and granodiorite) and marble. However, controversy persists regarding the genetic classification and metallogenic mechanism of this deposit. Through a field investigation, single mineral in situ geochemical analysis, whole-rock geochemical analysis, and Fe isotope determination, the following conclusions are made: (1) Ti-(Ni/Cr) and (V/Ti)-Fe diagrams indicate that the magnetite from all studied rocks underwent hydrothermal metasomatism, while (Ni/(Cr + Mn))-(Ti + V) and (Ca + Al + Mn)-(Ti + V) diagrams suggest a skarn origin for these magnetites. Therefore, it can be inferred that the Kaladawan iron deposit is skarn-type. (2) The iron ore exhibits similar rare-earth-element characteristics to the altered basalt. Additionally, the altered basalts (δ⁵⁶Fe = 0.024~0.100‰) are more enriched in light Fe isotopes than the unaltered basalts (δ⁵⁶Fe = 0.129~0.197‰) at the same location, indicating that the ore-forming materials of the Kaladawan iron ore are mainly derived from basaltic rocks. (3) According to the law of mass conservation and the intermediate Fe isotopic composition of the iron ore between the granodiorite and basalt, the hydrothermal fluid for the formation of iron ores was inferred to be derived from the late intrusive granodiorite. Full article

In the field of stone conservation, the removal of iron stains is one of the most challenging issues due to the stability and low solubility of the ferrous species. In the present paper, three different chitosan-based hydrogels added with acetic, oxalic or citric acids are applied on different lithotypes, i.e., granite, travertine and marble, widely diffused in monumental heritages, and artificially stained by deposition of a rust dispersion. The reducing power of carboxylic acids is combined with the good chelating properties of chitosan to effectively remove rust from stone surfaces. As evidenced by colorimetry on three samples of each lithotype and confirmed by ¹H-NMR relaxometry and SEM/EDS analyses, the chitosan-oxalic acid hydrogel shows the best performance and a single application of 24 h is enough to get a good restoration of the stone original features. Lastly, the chitosan-oxalic acid hydrogel performs well when a rusted iron grid is placed directly on the lithic surfaces to simulate a more realistic pollution. Current work in progress is devoted to finding better formulations for marble, which is the most challenging to clean or, with a different approach, to developing protective agents to prevent rust deposition. Full article

Sperm cryopreservation is a valuable tool for breeding, conservation, and genetic improvement in aquatic resources, while oxidative damage will cause a decline in sperm quality during this progress. Melatonin (MT), a natural antioxidant hormone, is used as an additive in sperm cryopreservation to reduce cellular damage from oxidative stress. Here, we aimed to investigate the effect of adding MT to the freezing medium in sperm cryopreservation of brown-marbled grouper (Epinephelus fuscoguttatus). Different concentrations of MT (0, 0.1, 0.25, and 0.5 mg/mL) were tested. We evaluated sperm motility, viability, apoptosis, mitochondrial membrane potential (MMP), and fertilization ability to assess the effects of MT supplementation. Our results demonstrated that the addition of MT to the extender improved the post-thaw motility, MMP, and fertilization ability of brown-marbled grouper sperm. The total motility, curvilinear velocity, straight linear velocity, and average path velocity in MT-treated groups (0.1 and 0.25 mg/mL) exhibited significantly higher values than that of the control group. A higher MMP (p < 0.05) was observed in the group treated with 0.25 mg/mL MT, suggesting that supplementation of MT in the extender might be able to protect mitochondrial membrane integrity effectively. Regarding fertilizing ability, 0.25 mg/mL MT yielded a significantly higher hatching rate than the control. An adverse effect was found with the concentration of MT up to 0.5 mg/mL, suggesting the possible toxicity of a high-dose addition. In this study, we optimized the sperm cryopreservation protocol of brown-marbled grouper, which might be valuable for sperm cryopreservation and sample commercialization of groupers and other fish. Full article

Cultural heritage stone materials frequently experience significant discoloration induced by copper corrosion products, especially calcareous stones associated with bronze or copper statues and architectural elements. This alteration originates from the corrosion of unprotected copper, resulting in the formation of various Cu minerals and the migration of soluble ions to adjacent stone materials. Traditional cleaning methods involve mechanical, chemical, and laser techniques, which are generally time-consuming, costly, not ecological, or can possibly damage original materials. The loading of highly effective chelating agents, such as ethylenediaminetetraacetic acid (EDTA), into hydrogels has recently been exploited. However, the preference for synthetic hydrogels has been prominent until now, although they lack renewability and biodegradability and require high costs. This study explores for the first time the potential to clean copper corrosion with bacterial nanocellulose (BC) loaded with EDTA as a biologically based, sustainable, and biodegradable hydrogel. The BC hydrogel was characterised by field emission–scanning electron microscopy (FE–SEM), X-ray diffraction analysis (XRD), attenuated total reflectance–Fourier transform infrared spectroscopy (ATR–FTIR), simultaneous thermal analysis (TG-DSC), and tensile testing. It revealed a nano-fibrous structure with high crystallinity and purity and mechanical properties suitable for cultural heritage applications. The EDTA-loaded hydrogel effectively removed copper stains from marble after 120 min of application. Micro-Raman and colorimetric analyses assessed the cleaning efficacy. The study introduces bacterial nanocellulose as a green and effective alternative for heritage conservation, aligning with sustainable methodologies in stone conservation. Full article