Mineralogical and Chemical Tracing of Dust Variation in an Underground Historic Salt Mine

Preliminary investigations of microplastic pollution in karst systems, from surface watercourses to cave waters

Microplastic pollution in different environments has increasingly been documented in detail in recent times, but it is still poorly studied in caves and karst aquifers. To deepen the knowledge of microplastic pollution, for karst environment protection and conservation purposes, we collected and investigated different water samples from a karst area of Italy, considering connected surface and cave waters. Microplastics were extracted from water samples by filtration and subjected to organic matter removal with 15% hydrogen peroxide solution. Microplastics on filters were counted and characterised (size, colour, shape) via visual identification under a microscope, with and without UV light, exploiting fluorescence given by fluorescent whitening additives contained in plastic materials. Finally, spectroscopic analyses were carried out on 10% of the microplastics observed on each filter. The concentration of microplastics in cave waters varied from 12 to 54 items/L, with a mean value of 28 items/L. In the surface water of a tributary, it was of 23 items/L, and in the downstream, it was 29 items/L. Fibres represented the most abundant shape (95.1%) in the karst system waters, and most microplastics (82.9%) were smaller than 1 mm. The majority of the microplastics were fluorescent under UV light (84.8%), and most fluorescent particles were transparent (46%). However, black microplastics (68%) were more common among the non-fluorescent ones. Polyethylene (51.7%) was the main type of microplastics found in the karst system waters. Our results show the presence of microplastics in karst systems and provide useful information for future research. Karst aquifers are open systems, subjected to possible contamination by surface pollutants. Microplastics in karst systems can be consumed by animals, damage ecosystems and contaminate water resources; surface karst areas and underground environments should therefore be monitored and protected, especially regarding the management of water resources. To further understand the sources and transport of microplastics within a karst system, analyses on a greater range of surface and subterranean waters throughout the world are required.

Application of Digital Twins and Metaverse in the Field of Fluid Machinery Pumps and Fans: A Review

Digital twins technology (DTT) is an application framework with breakthrough rules. With the deep integration of the virtual information world and physical space, it becomes the basis for realizing intelligent machining production lines, which is of great significance to intelligent processing in industrial manufacturing. This review aims to study the application of DTT and the Metaverse in fluid machinery in the past 5 years by summarizing the application status of pumps and fans in fluid machinery from the perspective of DTT and the Metaverse through the collection, classification, and summary of relevant literature in the past 5 years. The research found that in addition to relatively mature applications in intelligent manufacturing, DTT and Metaverse technologies play a critical role in the development of new pump products and technologies and are widely used in numerical simulation and fault detection in fluid machinery for various pumps and other fields. Among fan-type fluid machinery, twin fans can comprehensively use technologies, such as perception, calculation, modeling, and deep learning, to provide efficient smart solutions for fan operation detection, power generation visualization, production monitoring, and operation monitoring. Still, there are some limitations. For example, real-time and accuracy cannot fully meet the requirements in the mechanical environment with high-precision requirements. However, there are also some solutions that have achieved good results. For instance, it is possible to achieve significant noise reduction and better aerodynamic performance of the axial fan by improving the sawtooth parameters of the fan and rearranging the sawtooth area. However, there are few application cases of the Metaverse in fluid machinery. The cases are limited to operating real equipment from a virtual environment and require the combination of virtual reality and DTT. The application effect still needs further verification.

Sustainable Tourism and Conservation of Underground Ecosystems through Airflow and Particle Distribution Modeling

Underground ecosystems are often of interest for the tourism industry due to their important naturalistic and cultural heritage. Since these underground ecosystems are almost completely isolated, external agents (such as human presence) can easily disrupt their chemico-physical and biological processes, which can affect, sometimes irrevocably, their natural equilibrium, placing the preservation of such sites at risk. The most sensible managers of caves, catacombs, mines, and all the accessible cultural sites are searching for methods to control these dynamics and the modeling appears to be effective in preventing scenarios of the known impacts as well as suggesting strategies for their mitigation. In this study, by employing finite element analysis by the COMSOL Multiphysics software and reproducing, in a simplified way, a section of the tourist trail of the Pertosa-Auletta Cave (Italy), for the first time we provided a fact-finding survey of the airflow and the scattering and subsequent deposition of particles transported by tourists. Taking into account discontinuities in the pathway, the simulations rebuilt the possible natural airflow line, reproducing the particle movements induced by different tourist loads, whose high numbers increase the swirling movement of air masses, promoting a higher dispersion of particles, even in the remote cave areas. Performed simulations clearly indicated both the speed and direction followed by particles, as well as deposition sites, highlighting potential hotspots of damage, and demonstrating that the employed approach can be an excellent tool for planning the management of these extraordinary ecosystems, foretelling anthropogenic impacts, and supporting managers in decision-making processes.