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Skeletal remains from archaeological and forensic contexts are commonly used for various analyses, including DNA. Our research investigates relatively fast and inexpensive ATR-FTIR spectroscopy with further data manipulation as a potential pre-screening technique for assessing the preservation state of skeletal remains. We seek to correlate spectra and chemometric indices with the biological, chemical, and physical composition of the skeletal tissue, and the quality and quantity of DNA preserved in the tissue, also considering the skeletal element, absolute age, and environmental conditions to which the remains have been exposed. Our research focuses on human bones and teeth derived from archaeological, WWII and forensic contexts. The samples are cleaned and pulverized according to established methodological procedures for DNA extraction. DNA is extracted and quantified, while the remaining powder is analysed by ATR-FTIR spectroscopy. The obtained spectra are manipulated to extract the chemometric indices, which are the base for statistical analyses, machine learning, and prediction algorithms. A compilation of results from several studies shows that ATR-FTIR spectra present a solid base for researchers to better understand the preservation state of phosphates, carbonates, and collagen in the skeletal tissues, assessment of post-mortem interval, and the preservation of the DNA. Although many questions still need to be answered, ATR-FTIR spectroscopy with further data manipulation has a high potential for research of taphonomic changes, PMI and DNA preservation in human skeletal remains.

Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy is a relatively fast and inexpensive but reliable method that can be used as a rough screening tool for DNA preservation. Although it is an excellent analytical tool, it only provides relative information on the chemical structure of heterogeneous materials such as bone and its usefulness and accuracy for predicting the preservation of DNA in samples originating from different body regions of minimally altered remains was never tested before. 144 bone samples were collected from different body regions of three individuals discovered in a Second World War mass grave. DNA was extracted and quantified, followed by STR typing. Samples were analysed with ATR-FTIR spectroscopy. Comparing the preservation state of DNA and chemometric indices, the usefulness of the method was tested. Correlations between the DNA preservation and chemometric indices were highly variable, especially when considering different body regions. Best DNA preservation was correlated with a balanced ratio between carbonates and phosphates, and with high collagen quality and quantity. It seems that, when dealing with relatively young and well-preserved remains, more attention should be paid to collagen quality. In addition, the results indicate that DNA quality and DNA quantity correlate differently with chemometric indices.

Spectroscopy of skeletal tissues is increasingly used in various fields, including legal medicine, forensic science, and archaeology. As it is fast and technically and financially affordable yet accurate and widely applicable, spectroscopy is often used when investigating skeletal tissues. Despite its usefulness, the heterogeneity of skeletal tissues highly affects their chemical composition and complicates the interpretation of the spectroscopy results. Though the research on the use of spectroscopy and skeletal tissues from various contexts is growing, little is known regarding the differences in the chemometric indices caused by intra-skeleton variability. Objectives The objectives were a comparison of the chemometric indices between teeth and bones, between different bone classes, and between the skeletal elements within a bone class as well as an attempt to correlate the observed similarities or differences in chemometric indices to the functional or structural differences of skeletal elements. Materials and Methods Different skeletal elements of three individuals were analysed with attenuated total reflectance (ATR)–Fourier Transform Infrared (FTIR) spectroscopy and compared. Results Significant differences between the chemometric indices of the bones and teeth were observed and meaningfully correlated with their structural differences. Though more subtle and harder to understand, significant differences were also observed between and within the bone classes and were tentatively correlated with their structural and functional differences. Discussion The observed variability agrees with other studies that stress the importance of intra-skeleton variability, which should be acknowledged when using spectroscopy to investigate skeletal tissues.

The formation of giant hailstones is a rare weather event that has devastating consequences in inhabited areas. This hazard has been occurring more frequently and with greater size of hailstones in recent years, and thus needs to be better understood. While the generally accepted mechanism is thought to be a process similar to the formation of smaller hailstones but with exceptional duration and stronger updrafts, recent evidence suggests that biotic and abiotic factors also influence the growth of these unusually large ice chunks. In this study, we improved these findings by determining the distribution of a wide variety of these factors throughout the hail volume and expanding the search to include new particles that are common in the environment and are of anthropogenic origin. We melted the concentric layers of several giant hailstones that fell to the ground over a small region in Slovenia in 2019. The samples, up to 13 cm in diameter, were analyzed for biotic and abiotic constituents that could have influenced their formation. Using 16S rRNA-based metagenomics approaches, we identified a highly diverse bacterial community, and by using scanning electron microscopy and Raman spectroscopy, we found natural and synthetic fibers concentrated in the cores of the giant hailstones. For the first time, we were able to detect the existence of microplastic fibers in giant hailstones and determine the changes in the distribution of sand within the volume of the samples. Our results suggest that changes in the composition of hail layers and their great diversity are important factors that should be considered in research. It also appears that anthropogenic microfiber pollutants were a significant factor in the formation of the giant hailstones analyzed in this study.