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For the first time, a high-resolution record of natural events of the Late Glacial and Early Holocene (14150–9730 cal BP) was obtained for the Upper Kama basin based on sedimentary succession in Novozhilovo Lake (Kama–Keltma lowland). The results of the reconstruction of sedimentation setting, based on paleobotanical and sedimentological analyses, as well as radiocarbon dating, are presented. The beginning of formation of the lake was apparently preceded by a period of predominantly alluvial morpholithogenesis, which presumedly corresponded to the Late Pleniglacial. There are four stages in the evolution of the lake basin: the first three were characterized by lacustrine-alluvial sedimentation that was predominantly minerogenic, and the fourth stage was marked by typical lacustrine organogenic sedimentation. The first stage covered the Bølling–Allerød interstadial period from 14 150 to 13 500 cal BP, which was characterized by the accumulation of sand under conditions of high water flow. At the Allerød–Younger Dryas boundary, bioproductivity increased significantly. During the second stage (13 500–12 420 cal BP), water exchange slowed down and organomineral lake sediment formed. The third stage of the transitional sedimentation refers to the Younger Dryas–Early Holocene (12 420–10 700 cal BP). During that time, alluvial inputs predominated, with a decrease in the organic matter content. Finally, the fourth stage of the eutrophic lake (10 700–9730 cal BP) was characterized by a high organic matter content in the sediment and the aleurite fraction increased in the grain-size composition.

•Diatom persistence on clothing following one month of wear was tested.•Two or three stages of persistence were identified depending on clothing type.•Retention (%) dynamics were significantly impacted by clothing type but not seasonality.•The species-richness of a recovered assemblage decreased temporally.•Long-term persistence indicates evidential potential of diatoms over investigative timescales. Freshwater diatoms offer valuable circumstantial forensic indicators, with a growing empirical research base aiming to identify and understand some of the spatial and temporal factors affecting their validity as trace evidence. Previous studies demonstrated that recipient surface characteristics, environmental variability, and individual species traits influence the initial transfer of freshwater diatoms to clothing. However, no previous research has sought to consider the impact of these and other variables on the persistence of transferred diatoms over investigative timescales. Therefore, this study aimed to identify and explore diatom retention dynamics on clothing following wear over time (hours to weeks). A series of experiments were designed to examine the impact of clothing material, seasonality, and time since wear (persistence interval) on the total number and species-richness of diatoms recovered and their relative retention (%) over time. Nine clothing swatches were immersed in a freshwater environment and then worn for one month in the spring. Subsamples were retrieved at regular intervals (e.g. 30 mins, 1 h, 8 h, 24 h) up to one month, diatoms were extracted using a H2O2 method, and examined microscopically. Three clothing materials were subject to the same experiment in the winter to generate a seasonal comparison. The results broadly identified three stages of diatom persistence on clothing – rapid initial loss, variable intermediate decay, and sustained long-term presence. Clothing material significantly impacted the number of diatoms recovered and retention dynamics over time, with complex interactions identified with seasonality. Although fewer diatoms were recovered in the winter, overall retention trends were consistent at the different times of year. The findings demonstrate that diatoms can be recovered from clothing, even weeks or months after an initial transfer, yielding a useful environmental trace indicator for forensic reconstructions over investigative timescales. The impact of clothing material and seasonality on persistence identified cotton, acrylic, and viscose clothing as the most reliable temporal repository of diatom trace evidence, with a more abundant forensic assemblage available for forensic comparisons in the spring.

Background: diatoms are unicellular algae that have been used for more than a century for forensic purposes to diagnose drowning, with more or less success depending on the historical era. Although many years have passed, scientific research on diatoms has never ceased, which testifies to their enduring allure in forensics. Of course, diatom research has evolved and expanded over time, changing with the availability of new techniques and technologies. The volume of articles and their production over a period of many years has resulted in old, current, and new knowledge on diatoms being scattered over a large number of books and articles. Objectives: the purpose of this narrative literature review is, therefore, to summarize all this information and bring it together in a single work that can be useful for those who are studying diatoms and their usefulness for forensics for the first time, for those who are looking for proven methods of analysis, and finally for those who are interested in exploring new frontiers of research. Methods: a comprehensive literature search that included all studies dealing with the applications of diatoms in forensic science was performed in the most popular electronic databases. Results: traditional methods have been complemented by molecular and imaging methods and, more recently, by artificial intelligence. In addition, new biological substrates have been found for the analysis of diatoms. Conclusions: all this has led, on the one hand, to the consolidation of a whole body of knowledge on diatoms, on which this forensic analysis is still based, and, on the other hand, has opened up numerous new research directions.

•Diatom species retention on clothing is tested following wear over one month.•Persistence is significantly impacted by diatom size but not shape.•Clothing type and sample season affect species richness and assemblage dynamics over time.•Abundant taxa are more consistently retained on clothing compared to rarer species.•Analysis of species temporal dynamics is recommended to support forensic interpretations. Diatoms are a useful form of environmental trace evidence, yielding a circumstantial link between persons and scenes of forensic interest. A developing empirical research base has sought to understand those factors affecting the transfer and persistence of freshwater diatoms on clothing and footwear surfaces. Although an initial study has demonstrated that diatoms can persist on clothing following weeks of wear, no previous research has explored the temporal dynamics of a persistent species assemblage over timescales pertinent to forensic investigations. This study therefore aimed to determine if: (1) valve morphology (size and shape) influences diatom persistence, (2) the relative abundance of taxa within an assemblage affects retention, and (3) a persistent diatom assemblage retrieved from clothing after one month can reliably be compared to the site of initial transfer. To build on previous research findings which highlighted the impact of substrate and environmental seasonality on diatom transfer and persistence, here, nine clothing materials were tested in spring before a seasonal comparison in the winter. Fabric swatches were immersed in a freshwater river, worn attached to clothing, and subsamples retrieved at regular intervals (hours, days, weeks) up to one month post-immersion. Diatoms were extracted using a H2O2 technique and analysed via microscopy. The results indicated that smaller diatoms (< 10 µm) are retained in significantly greater abundance, with no statistically significant difference between centric and pennate diatom loss over time. Although a persistent species assemblage was relatively stable over the one month of wear, significant differences were identified between clothing substrate in the spring and between the seasonal samples. The most abundant environmental taxa were consistently identified in the forensic samples, with greater variability attributed to the retention of relatively less common species. The findings suggest that, despite a loss in the abundance and species-richness of diatoms retrieved from clothing over time, a persistent assemblage may provide a useful circumstantial link to the site of initial transfer. The complex relationships between clothing type, environmental seasonality, and time since wear on retention, emphasise the need for diatom trace evidence to be carefully interpreted within an exclusionary framework, and the significance of any casework findings to be determined with reference to empirical evidence bases.

The sediments of shallow basins formed on along the coast of the Baltic Ice Lake in the Late Glacial are a valuable source of information for reconstructing the paleoenvironment. A detailed diatom analysis, along with chronological and lithological studies, was performed for the sediments of one of these paleoreservoirs, uncovered in the Kulikovo section (Sambian Peninsula, Kaliningrad Region of the Russian Federation) and dated to 14,000–12,500 calBP. As a result of this study, the essential diversity of Late Glacial diatoms was revealed and 204 species were found. Among them, benthic and epiphytic species belonging to the group of oligohalobous indifferents predominate. The most typical species are Pseudostaurosira brevistriata, Staurosirella ovata, Gyrosigma attenuatum, G. acuminatum, Amphora affinis, Epithemia adnata and Cymbopleura inaequalis. A comparison with available regional data showed that the mass development of pioneer epiphytic diatoms of the Fragilariaceae in the Allerød is common to most of the paleoaquatic ecosystems. A local feature of the Kulikovo paleoreservoir, along with a wide range of ecological diatom groups, is the episode of massive development of Gyrosigma spp., benthic diatoms capable of living in streaming water, in the first half of the Allerød. The Kulikovo diatom assemblages reacted sensitively, not only to the main environmental shifts of the Allerød and Younger Dryas, but also to smaller-scale climatic events, such as Herzensee Oscillation (GI-1b) and changes in hydrological regimes (water level fluctuations, flow rate) caused by local environmental transformations.

The results of the comprehensive study (diatom and pollen and spore analysis, and 14 С-dating) of Holocene bottom sediments from a lake on the shore of Kandalaksha Bay, White Sea, at the Keret’ River mouth, are reported. Three stages in the evolution of the lake basin: marine, transitional, and lacustrine, were recognized. Diatom complexes, typical of each facies, were described. Pollen, spores and non-pollen palynomorphs were shown to indicate marine, transitional, and freshwater sedimentation conditions. Sea level was found to decrease 7200 cal. y.a. A marine sedimentation environment was succeeded by a lacustrine environment ca.6700 cal. y.a. The position of the sea shoreline in the study area at that time was determined. Data obtained by pollen and spore analysis were used for relative dating of postglacial strata. Vegetation, evolving from the end of the Early Holocene to the present, was reconstructed.

The grain size of lake sediments has been widely used to reconstruct environmental processes. However, the various components of lake sediments are influenced by different factors, and therefore the environmental significance of grain-size variations may be complex. For example, in situ authigenic biological siliceous components cannot be used to indicate variations in hydrodynamic conditions. Here we present a case study of the effects of diatoms on the grain size of the sediments of Lake Kanas in NW China. The analyses consist of measurements of bulk sediment grain size and biogenic silica, together with microscope observations. Based on both light and scanning electronic microscope observations, two large diatom species, Campylodiscus hibernicus Ehrenberg and Ellerbeckia arenaria (Moore) Crawford, were found to be abundant in sediment samples with a large bulk-sediment grain size, and they contributed substantially to the biogenic silica content and the measured bulk sediment grain size of the core. A quantitative assessment of the effects on grain size was made, and the study has a broad significance for evaluating the effects of diatoms on sediment grain-size distributions in other lakes. Because diatoms may deposit in situ or could be transported differently from other clastic material, the explanation of hydrodynamics could be misled if the influence of diatom has not been excluded. Therefore, we suggest BSi content should be tested to assess the diatom effect prior to grain-size analysis of lake sediments, together with microscope check of diatoms if BSi content is higher than 10%.

A diatom analysis of a peat deposit from Shemya Island (Aleutian Arc, USA) is performed, and the dynamics of the diatom community are described. According to the radiocarbon dating, the formation of the deposit began 9300 cal. years BP. Principal component analysis made it possible to relate the dynamics of the diatom community to certain environmental conditions and the factors that influenced the coastal ecosystems during its formation. The following factors (predictors) were considered: the influence of age, zoo- and anthropogenic effects, and changes in climatic conditions. Sea level change was the main driver of the diatom community in the studied water body having a continuous direct and indirect influence on the studied small water body, i.e., by bird colony formation and more humid and coastal conditions. Since 3000–2000 cal. years BP, the anthropogenic factor (hunting depression of the bird colony) also became significant. During the whole water body lifetime and following peat formation, the diatom community was influenced by groups of factors: global factors (e.g., sea level rise) caused gradual change of local factors, which resulted in smooth shifts in community. In contrast, local factor influence (bird colony rise and fall due to human activity) caused abrupt and transient shifts. We can hypothesize that the relatively stable global environmental conditions in the Late Holocene were an auspicious background to see abrupt changes due to influence of the zoogenic and anthropogenic factors. We believe that further works on the material from other islands will make it possible to form a general picture of changes in the diatom communities in the Holocene and interpret it in connection with climatic changes in the region.

AbstractWe studied sedimentary archives on the Karelian coast of the White Sea (area of the White Sea Biological Station, Moscow State University) from various objects—filling of the paleoseismic fault trench, marine terraces, and buried shell lenses—to obtain new data on the relative sea level dynamics in the Holocene in the areas where block tectonic movements took place. The specific features of the formation of subfossil malacofauna taphocenoses in Kandalaksha Gulf, changes in the sedimentation environment under the conditions of uplifting coast, and traces of strong seismicity in the late glacial and postglacial periods are also revealed.

We studied diatoms in a 55.5-cm-long sediment core from a subalpine lake in northern Taiwan, Tsuifong Lake (TFL), to investigate environmental changes from AD 490 to present. Diatom assemblages of the last century were dominated by acidophilous species, whereas alkaliphilous taxa dominated the record between AD 1480 and 1910. Over the studied time frame, four decadal periods with high precipitation were inferred from evidence of elevated soil input from the watershed, supported by the stable isotope signatures (δ¹⁵N, δ¹³C) of organic matter and magnetic susceptibility of the sediments. We compared the inferred changes in pH of TFL to values obtained from three other Taiwanese subalpine lakes. The present study revealed that elevated precipitation was associated with increased solar irradiance over the last five centuries, with a stable dry period between AD 490 and 1450. Acidification of TFL in the last ~100 years was a consequence of deforestation and acid rain.