THE ROLE OF TECHNICAL AND NATURAL SCIENCES IN STONE MONUMENTS CARE

Stone monuments maintenance requires the systematic approach which should be based on the cooperation among specialist through more branches, especially from humanities, natural and technical sciences. The main aim of this article is to present the benefit of the cooperation among geologists and civil engineers and share preliminary results of the Czech Ministry of Culture project DG20P02OVV021 “Stone surface topography and its application in stone element restoration field”. Historic stone surfaces often contain stonemasons tool traces as an undoubtable part of historical monument value. The study and protection of the testimony of past is therefore very important. As a part of our project, we are conducting field and laboratory research of historic stone surfaces bearing the original tool traces. The studied area is the Prague urban conservation zone for its stone monuments richness from Romanesque to present days. First, the geological research of the stone masonry surface is conducted in the cooperation with archaeologists. The tool traces are documented, and the state of stone is described. Because of the negative influence of weathering processes on the stone durability, respectively tool traces, we decided to monitor the chosen historical stone surface using the hyperspectral analysis. Based on the analysis results we will be able to better understand the behaviour of stone surface and traces on it during the time.

Morphological and physico-chemical properties of Cryosoils in the Bulgarian antarctic base on Livingston island, Antarctica

Under the global climatic changes and anthropogenic impacts on the environment, information about characteristics and specific features of soils in remote regions as Antarctica is valuable and could be used as references. This study focuses on the analyses of original data about the physico-chemical composition and micromorphological structure of Cryosols, collected in 2019 from the sampling area of the Bulgarian Antarctic Base “St. Kl. Ohridski” located on Livingston Island, Antarctica. The studied Cryosols are moderately acidic with slow and incomplete transformation of organic residues. The organic carbon content is low, except for soils formed under the influence of an ornithogenic factor. The mezo- and micromorphological observations show a predominance of the mineral phase, weakly affected by weathering processes. Many soil pores and voids are observed, which facilitates water-air and intra-soil exchange during the short Antarctic summer. The analyses showed an evidence for the connection of the processes of soil formation of Cryosols in the region with the pulsating degradation of the glaciers.

Mineralogical Transformations in Granitoids during Heating at Fire-Related Temperatures

Fire is a major decay agent of rocks and can generate immediate catastrophic effects as well as directional and anisotropic damage that affect long-term weathering processes. Temperature increase is the most relevant factor, among other components in a fire, generating mineral transformations and bulk mechanical damage. Mineralogical changes at high temperatures are key to understanding the overall mechanical behaviour. However, most studies to date were carried out after rock specimens were heated to a target temperature and cooled down to room temperature. Therefore, these studies are missing the observation of the actual mineral processes during heating. This paper aims to compare mineralogical changes in crystalline rocks during heating by means of XPS and different XRD techniques. Samples of four different granitoids were heated to several temperatures up to 1000 °C to evaluate their chemical and structural changes. Results show how standardised thermal expansion coefficients are not a suitable indicator of the bulk effect of high temperatures on rocks. Results also show how thermal expansion estimations from XRD lattice measurements may be an alternative to bulk dilatometric tests, as they can be performed with limited sampling, which may be necessary in some studies. Nevertheless, XRD and XPS results need to be interpreted carefully in relation to the bulk effects of temperature increase in the rocks, as the structural behaviour may seemingly contradict the macroscopic effect.

Effects of leachates from UV-weathered microplastic on the microalgae Scenedesmus vacuolatus

Plastics undergo successive fragmentation and chemical leaching steps in the environment due to weathering processes such as photo-oxidation. Here, we report the effects of leachates from UV-irradiated microplastics towards the chlorophyte Scenedesmus vacuolatus. The microplastics tested were derived from an additive-containing electronic waste (EW) and a computer keyboard (KB) as well as commercial virgin polymers with low additive content, including polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), and polystyrene (PS). Whereas leachates from additive-containing EW and KB induced severe effects, the leachates from virgin PET, PP, and PS did not show substantial adverse effects in our autotrophic test system. Leachates from PE reduced algae biomass, cell growth, and photosynthetic activity. Experimental data were consistent with predicted effect concentrations based on the ionization-corrected liposome/water distribution ratios (Dlip/w) of polymer degradation products of PE (mono- and dicarboxylic acids), indicating that leachates from weathering PE were mainly baseline toxic. This study provides insight into algae toxicity elicited by leachates from UV-weathered microplastics of different origin, complementing the current particle- vs. chemical-focused research towards the toxicity of plastics and their leachates. Graphical abstract

Evidence of Microplastic Size Impact on Mobility and Transport in the Marine Environment: A Review and Synthesis of Recent Research

Marine Microplastics (MPs) exhibit a wide range of properties due to their variable origins and the weathering processes to which they are exposed. MP’s versatile properties are connected to their dispersal, accumulation, and deposition in the marine environment. MP transport and dispersion are often explained by analogy with sediments. For natural sediments, one of the key features linked to transport and marine morphology is particle size. There is, however, no size classification defined for MP particles and MPs constitute all plastic particles sized smaller than the threshold of 5 mm. In this study, based on existing knowledge in hydrodynamics and natural sediment transport, the impact of MP size on turbulent entrainment, particle settling, and resuspension is described. Moreover, by analyzing several quantitative studies that have provided size distribution, size-selective accumulation of MPs in various regions of the marine environment is reported on. The preferential presence of MPs based on their size in different marine compartments is discussed based on the governing hydrodynamic parameters. Furthermore, the linkage between polymer properties and MP shape and size is explored. Despite the evident connection between hydrodynamic transport and MP size presented, classification of MP size presents challenges. MP size, shape, and density appear simultaneously in the definition of many hydrodynamic parameters described in this study. Unlike mineral sediments that possess a narrow range of density and shape, plastics are manufactured in a wide variety of densities and marine MPs are versatile in shape. Classification for MP size should incorporate particle variability in terms of polymer density and shape.

Genome and Transcriptome Sequencing of Novel Pseudomonas sp. NLX-4 Strain Involved in Bio-Restoration of Over Exploited Mining Sites

Microbial weathering processes can significantly promote soil properties and enhance rock to soil ratio. Some soil-inhabiting bacteria exhibit efficient rock-dissolution abilities by releasing organic acids and other chemical elements from the silicate rocks. However, our understanding of the molecular mechanisms involved during bacterial rock-dissolution is still limited. In this study, we performed silicate rock-dissolution experiments on a novel Pseudomonas sp. NLX-4 strain isolated from an over-exploited mining site. The results revealed that Pseudomonas sp. NLX-4 strain efficiently accelerates the dissolution of silicate rocks by secreting amino acids, exopolysaccharides, and organic acids. Through employing genome and transcriptome sequencing (RNA-seq), we identified the major regulatory genes. Specifically, fifteen differentially expressed genes (DEGs) encoding for siderophore transport, EPS and amino acids synthesis, organic acids metabolism, and bacterial resistance to adverse environmental conditions were highly up-regulated in silicate rock cultures of NLX-4 strain. Our study proposes a novel bacterial based approach for improving the ecological restoration of over-exploited rock mining-sites.

Structural Diagnosis and Performance Assessment of Existing Masonry Aqueducts with Unknown Geometry

Masonry arch aqueducts, as important hydraulic structures, constitute an meaningful part of old irrigation infrastructures in China. The constituent materials deteriorate over time, caused by weathering processes and the defect development, influences the mechanical performance of these structures. The paper presents a comprehensive approach to evaluate the structural safety of an old masonry aqueduct with uncertain mechanical parameters and unknown geometric dimensions. This approach employed the 3D terrestrial laser scanning (TLS) to measure the geometric dimensions, and the discrete element analysis (DEM) to analyze the current operational behaviour state of the masonry aqueduct. As a case study, the Zhaimen masonry arch aqueduct in the famous Red Flag Canal, operating for more than 50 years, was investigated in this study. Obvious defects, such as the continuous loss and falling of mortar and the arch ring detaching, appeared in this old aqueduct. The TLS measurement information was used to construct a DEM model. Then this numerical model was applied to analyze the current performance of the exiting masonry arch aqueduct. The results show that the upper structure and the supporting structure can still be stable assuming that the mortar with no bond strength. In other words, the deterioration of the mortar, due to natural weathering and Calcium ion dissolution caused by natural environment and leakage, would not have a fatal impact on the structural safety. The proposed structural diagnosis and performance assessment approach can provide a reference to safety evaluation for similar masonry arch aqueducts.

Improving the Methods for Processing Hard Rock Aquifers Boreholes’ Databases. Application to the Hydrodynamic Characterization of Metamorphic Aquifers from Western Côte d’Ivoire

Statistical analysis of a borehole database, linear discharges, and water strikes processing enabled an understanding of the structure, geometry and hydrodynamic properties of the metamorphic hard rock aquifers from the Montagnes District, Western Côte d’Ivoire. The database comprises 1654 boreholes among which 445 only were usable for this research work after its pre-processing. Analysis shows that the structure of the aquifer is similar to that observed in several other areas in the world: it developed due to weathering processes, comprises the capacitive saprolite, 10–20 m thick on average, and an underlying transmissive fractured layer, overlying the unweathered impermeable hard rock. The fractured layer is 80 m thick, the first 40 to 45 metres being its most productive zone, with a 11.3 m3/h median productivity. This research shows that metamorphic aquifers exhibit similar aquifer properties (thickness, hydrodynamic parameters) as plutonic ones and that there is interest in using such databases for research and other purposes. However, a rigorous pre-treatment of the data is mandatory, and geological data from published maps must be used instead of the geological data from the database. A previous methodology aiming at processing the boreholes’ linear discharges was improved. It notably appears that the slope method must be preferred to the percentile method.