Burial Soil Research Articles

Фортификации Усть-Терсюкского городища эпохи Раннего Средневековья

The article analyses early medieval structures of the outer fortification line in Ust-Tersyuk hillfort by the Iset River. The research is based on excavation finds made in 2010 and 2023. The fortified cape settlement is surrounded by a protection structure all around. Besides, it has two transverse structures that separate the cape and gullies and form two sites. One of the sites is pentagonal, the other one is octagonal. It is established that the structure lasted through at least four periods of functioning. These periods are separated from one another by intervals of desolation several centuries each. During these idle intervals the burial soil profiles started to form. Two early episodes are associated with the Bakalskaya culture and dated 300–400s. At that time the highest point was isolated all around with a stake wall as a temporary defence until earth works are over. Later the stake wall was disassembled and replaced with a low rampart, a 2 m wide berm and a moat across the slopes. In 500–800s the Bakalskaya culture people enhanced the defence with a mound and a 1.1 m wide wall over the mound. The wall cavity was filled with soil brought from the settlement site. Differences in the design of the wall on the cape (fence) and in the west flank (log framework) can be interpreted as different time of construction or troubled material delivery. The moat was relocated down the slope. The berm was enhanced to reach 5.5 m. In 1000s–1200s (Yudino culture) the moat around the hillfort was renovated. But the research is yet to establish the type of woks conducted on the ramparts. Every new episode of construction stands out with increasingly more efforts and attack marks. During the Bakalskaya culture the soil was meadow chernozem. The climate was warmer and humid due to close creeks. Later the climate got cooler and formed grey wood soil.

Laboratory and synchrotron x‐ray micro–computed tomography to shed light on degradation features of corroded Roman glass

AbstractThis study explores the three‐dimensional structure of Roman glass through the combined use of laboratory and phase‐contrast synchrotron x‐ray micro–computed tomography. This original approach validates a noninvasive analytical procedure designed to enhance the understanding of glass degradation mechanisms, crucial for the preservation of historical artefacts. The high‐resolution images obtained reveal the intricate internal structure and morphology of various forms of glass deterioration, including cracking, pitting, and the formation of multilayered iridescent patinas. The research provides compelling evidence of corrosion processes and interaction mechanisms with burial soil, shedding light on the chemical and physical interactions that occur over centuries. By characterizing and examining the long‐term alteration of ancient glass, this work contributes to the field of archaeometry, offering insights into how different types of glass withstand the test of time in diverse environmental conditions. The findings have important implications for conservation strategies, enabling better preservation techniques for glass artefacts.

An insight into the origin of elemental chromium in the lacquer of Qin terracotta warriors

The origin of elemental chromium for the archaeological weapons from the pits of Qin terracotta warriors in China has been highly controversial. Although previous studies have highlighted that the chromium on the surface of weapon originated from the contamination of surrounding lacquer, the exact origin of chromium in the lacquer remains unclear. In this work, the measurement by inductively coupled plasma-mass spectrometer (ICP-MS) firstly confirmed that the elemental chromium was indeed contained in the archaeological Qin original lacquer. Nevertheless, the amount of elemental chromium in the Qin lacquer was as low as 0.0759 μg/mg, disclosing that it was impossible to artificially add extra refined chromium-containing substance to the lacquer in the preparation of the terracotta warriors. The soil from the archaeological site of Qin lacquer was found to have a chromium amount of 0.0660 μg/mg by ICP-MS. After the hygrothermal and soil-buried aging cycles for the lab-prepared lacquer, the surface and depth elemental analyses by time of flight-secondary ion mass spectrometer (TOF–SIMS) showed a gradient distribution of elemental chromium from the surface to interior of aged lacquer, indicating the migration and enrichment behavior of elemental chromium from the burial soil towards the lacquer. To explore the migration mechanism of elemental chromium, fluorescence imaging technique was employed in combination with Fourier transform infrared spectrometry (FT-IR) and X-ray photoelectron spectroscopy (XPS) characterizations. The results revealed that catechol-containing fragments were formed during hygrothermal and soil-buried aging of lacquer and consequently coordinated with chromium ions, inducing the migration of elemental chromium towards the lacquer.

A preliminary study characterizing temporal changes in soil bacterial communities after dismembered bones were buried.

Determining the burial time of skeletal remains is one of the most important issues of forensic medicine. We speculated that the microbiome of gravesoil may be a promising method to infer burial time by virtue of time-dependent. As we know, forensic scientists have established various models to predict the postmortem interval of a decedent based on the changes in body and soil microbiome communities. However, limited data are available on the burial time prediction for bones, especially dismembered bones. In this exploratory study, we initially conducted 16S rRNA amplicon high-throughput sequencing on the burial soil of 10 porcine femurs within a 120-day period and analyzed the changes in soil microbial communities. Compared with the control soil, a higher Shannon index in the microbial diversity of burial soil containing bones was observed. Correlation analysis identified 61 time-related bacterial families and the best subset selection method obtained best subset, containing Thermomonosporaceae, Clostridiaceae, 0319-A21, and Oxalobacteraceae, which were used to construct a simplified multiple linear regression model with a mean absolute error (MAE) of 56.69 accumulated degree day (ADD). An additional random forest model was established based on indicators for the minimum cross-validation error of Thermomonosporaceae, Clostridiaceae, 0319-A21, Oxalobacteraceae, and Syntrophobacteraceae, with an MAE of 55.65 ADD. The produced empirical data in this pilot study provided the evidence of feasibility that the microbial successional changes of burial soil will predict the burial time of dismembered bones and may also expand the current knowledge of the effects of bone burial on soil bacterial communities.

Deep insights into biodegradability mechanism and growth cycle adaptability of polylactic acid/hyperbranched cellulose nanocrystal composite mulch

The widespread use of petroleum-based plastic mulch in agriculture has accelerated white and microplastic pollution while posing a severe agroecological challenge due to its difficulty in decomposing in the natural environment. However, endowing mulch film with degradability and growth cycle adaptation remains elusive due to the inherent non-degradability of petroleum-based plastics severely hindering its applications. This work reports polylactic acids hyperbranched composite mulch (PCP) and measured biodegradation behavior under burial soil, seawater, and ultraviolet (UV) aging to understand the biodegradation kinetics and to increase their sustainability in the agriculture field. Due to high interfacial interactions between polymer and nanofiler, the resultant PCP mulch significantly enhances crystallization ability, hydrophilicity, and mechanical properties. PCP mulch can be scalable-manufactured to exhibit modulated degradation performance under varying degradation conditions and periods while concurrently enhancing crop growth (wheat). Thus, such mulch with excellent performance can reduce labor costs and the environmental impact of waste mulch disposal to replace traditional mulch for sustainable agricultural production.

Multiregional Pb isotopic linear patterns and diagenesis: Isotopes from ancient animal enamel show Native American “foreign war trophies” are local ancestors

Skull burials are found all over the world and often are interpreted to be foreigners, sacrifices, or victims of warfare. The cause of ancient Native American skull deposits often leads to disagreement among scholars torn between warfare and ancestor veneration. Most previous research suggested a Caddo skull-and-mandible deposit (consisting of clusters of skulls and clusters of isolated mandibles) in southwest Arkansas, USA contained foreign victims of interregional warfare, representing at least 352 people (1253–1399 CE). While Sr isotopes are commonly used in archaeology to investigate such issues, they did not provide a conclusive answer to the geographic origin of the remains. This study advances the biologically available Pb method by constructing a large-scale multiregional Pb isotopic background with ancient animal tooth enamel and uses their associated linear patterns to evaluate human geographic origins. Evaluation of Pb contamination through diagenesis in human tooth enamel is evaluated and advanced using correlation analysis of trace elemental data from teeth and burial soil. A total of 180 animal teeth were processed from 28 ancient sites in the southcentral USA. Combining Pb isotopic linear patterning analysis with the Sr isoscape allows us to establish that the skulls and mandibles are local to southwest Arkansas and indicate or strongly suggest they are non-local to all other tested regions. This illustrates the importance of Pb isotopes in studies of human geographic origins. It also provides one cautionary tale that interpretations about violence related to detached skulls should be evaluated with appropriate methods and evidence and with a critical eye for other explanations. This study was conducted in collaboration with the Caddo Nation of Oklahoma and provided both the descendant community and researchers with answers to the questions surrounding the remains, serving as one example of how stakeholders can come together and produce positive outcomes.

Thermodynamic and spectroscopic data suggesting hypothetical humic fractions evolution on carbon cycle in soils

Soil organic matter is considered by soil scientists as the interlayer that connect alive with mineral sides of the soil. In addition, microorganisms have in soil organic matter a source of carbon as well as a source of energy. We can observe a duality that can be analyzed from a biological, physicochemical, or even thermodynamic sense. From this last point of view carbon cycle follows its evolution on burial soil, and under certain temperature and pression conditions, up to fossil fuels or coals through kerogen being humic substances the ending point of biologically linked structures. When biological aspects are minimized, physicochemical aspects are maximized and carbonaceous structures are a source of energy but resilient to microorganism actions. Under these premises, we have isolated, purified, and analyzed different humic fractions. Heat of combustion of these humic fractions here analyzed reflects this situation and fitted the list of evolution stage of carbonaceous materials that step by step accumulates energy. Theoretical value of this parameter calculated from studied humic fractions, and by combination of its biochemical macromolecules yielded an exaggerated value in comparison to the real and measured value indicating a complexity of these humic structures, more than simpler molecules. Heat of combustion and excitation-emission matrices by fluorescence spectroscopy of isolated and purified grey and brown humic materials revealed different values for each fraction. Grey fractions showed a higher heat of combustion values and shorter λexc/λem, whereas brown fractions showed a lower heat of combustion and a larger λexc/λem. These data together with previous chemical analysis indicated a deep structural differentiation that can be observed by the Pyrolysis MS-GC data of the studied samples. Authors hypothesized that this incipient distinction between aliphatic and aromatic cores could evolve independently up to fossil fuel on one hand and coals on the other hand but separately.

Biodeterioration Assessment of a Unique Old Pharaonic Kingdom Wooden Statue Using Advanced Diagnostic Techniques

A recently discovered Egyptian wooden statue of King Djedefre was studied together with some surrounding burial soil samples for assessing the statue biodeterioration. The wooden morphological characterisation identified the hardwood Acacia nilotica as the wood type. X-ray diffraction, micro-FT-IR spectroscopy, and scanning electron microscopy with an X-ray spectrometer were used to evaluate the wood deterioration degree and the soil contribution in wood biodeterioration. Microbiological analyses (fluorescent in situ hybridisation and polymerase chain reaction) were also performed to detect the microbial attack on the statue. The prolonged interaction of the statue with the burial environment caused a strong wood decay due to biotic (fungi and bacteria) and abiotic factors (e.g., humidity fluctuations of the burial environment), which caused the severe cracking and collapsing of the wood structures. The analyses of the burial soil mineral composition were relevant for obtaining an overall picture of the statue deterioration. The results are useful for planning the right conservation procedures for this very particular and important wooden statue. Furthermore, analysis of the woody cell wall will help in the selection of appropriate consolidation and recovery treatments. Because the statue is a unique single piece of wood, and the morphological observations indicated that it is a bald woman in a sitting position, this statue will provide new and interesting knowledge of Egyptian culture.

Understanding Necrosol pedogenetical processes in post-Roman burials developed on dunes sands

In Archaeology much emphasis is dedicated to bone preservation, but less attention is paid to the burial soil (i.e., Necrosol), despite its crucial role in governing the geochemical environment. The interaction between human remains and sediments starts after inhumation, leading to bidirectional physico-chemical changes. To approach these complex, bidirectional processes, we sampled at high resolution (n = 46) two post-Roman wooden coffin burials (one single and another double), and the coeval paleosol (n = 20; nearby pedo-sedimentary sequence). The samples were analysed for physical (grain size, colour) and chemical (pH; LOI; elemental composition: FTIR-ATR, XRF, C, N) properties. Principal component analysis enabled to identify five main pedogenetical processes: decalcification, melanization, acidification, neoformation of secondary minerals (i.e., clays) and enrichment in phosphorus. Melanization, acidification and phosphorous enrichment seem to be convergent processes in Necrosols—irrespective of the parent material. Decalcification may be restricted to carbonate containing soil/sediments. Despite not mentioned in previous research, clay formation might also be an overall process. Compared to the local, coeval paleosol, pedogenesis in the studied burial soils was low (double burial) to moderate (single burial). Our results also emphasize the need to study the finer soil fractions, as they provide clues both on soil formation and bone diagenesis.

Analysis of Microbial Community Structure and Diversity in Burial Soil of Yangguanzhai Cemetery.

As one of the common physical remains in archaeological discoveries, human bones are important bases for studying the history of human development, which is of great significance for exploring the evolution law of ancient human, reconstructing ancient human society, and tracking the development of human civilization. However, in the process of human bone burial, in addition to being affected by physical and chemical factors, it will also be affected by microorganisms in the buried soil, resulting in a variety of diseases. According to the determination and analysis of the microbial community structure and diversity in the burial soil of Yangguanzhai Site in Gaoling District in Xi’an city, Shaanxi Province, this paper attempts to explore the influence of microorganisms in the burial environment on human bones, in order to provide scientific proof for the microbial prevention and control of bone relics in the archaeological excavation site. For the first time, Illumina NovaSeq high-throughput sequencing technology was used to analyze the microbial community structure in the burial soil. At the phylum level, there were 8 dominant bacteria species in the soil samples of tombs, which were Firmicutes, Actinobacteriota, Actinobacteria, Proteobacteria, Acidobacteriota, Methylomirabilota, Chloroflexi, Bacteroidota. At the genus level, there were 12 dominant species in the soil samples of tombs, including MIZ17, MND1, Gaiella, oc32, Kroppenstedtia, Halomonas, Bacteroides, Dongia, Faecalibacterium, Nocardioides, Pseudomonas, Pseudonocardia. The overall microorganisms in the soil of Yangguanzhai Cemetery were relatively well-distributed, and the microbial community structure near human bones is the most abundant and diverse. Therefore, it is necessary to take some measures to control microorganisms and protect human bones.

Approaching mercury distribution in burial environment using PLS-R modelling

Mercury environmental cycle and toxicology have been widely researched. Given the long history of mercury pollution, researching mercury trends in the past can help to understand its behaviour in the present. Archaeological skeletons have been found to be useful sources of information regarding mercury loads in the past. In our study we applied a soil multi-sampling approach in two burials dated to the 5th to 6th centuries AD. PLRS modelling was used to elucidate the factors controlling mercury distribution. The model explains 72% of mercury variance and suggests that mercury accumulation in the burial soils is the result of complex interactions. The decomposition of the bodies not only was the primary source of mercury to the soil but also responsible for the pedogenetic transformation of the sediments and the formation of soil components with the ability to retain mercury. The amount of soft tissues and bone mass also resulted in differences between burials, indicating that the skeletons were a primary/secondary source of mercury to the soil (i.e. temporary sink). Within burial variability seems to depend on the proximity of the soil to the thoracic area, where the main mercury target organs were located. We also conclude that, in coarse textured soils, as the ones studied in this investigation, the finer fraction (i.e. silt + clay) should be analysed, as it is the most reactive and the one with the higher potential to provide information on metal cycling and incipient soil processes. Finally, our study stresses the need to characterise the burial soil environment in order to fully understand the role of the interactions between soil and skeleton in mercury cycling in burial contexts.

Post-depositional processes as the main determinants for the alterations caused in cockle shells found in São Julião archaeological site (Mafra, Portugal)

The presence of cockle shells in Mesolithic and Neolithic Portuguese archaeological sites located near the coast or estuaries is relatively common. Here we report the study of a collection of complete and fractured Cerastoderma edule (Linnaeus, 1758) shells (with umbo) recovered from a well-preserved midden dated from Late Mesolithic found at the São Julião archaeological site, unit C (Mafra, Portugal).In order to interpret the main morphological alterations observed in the archaeological shells, these were compared with modern specimens from alive animals and dead molluscs present in thanatocoenosis along the Portuguese coast, and also with shells experimentally subjected to overburden in soil.It was observed that shells from dead molluscs collected in thanatocoenosis present wear all over the surface and especially in the umbo region with the formation of a hole, which was not observed in the archaeological shells. Fractured archaeological shells resembled modern shells fractured by overburden in the laboratory. Experimentally, shells were found to be very resistant to fracture, requiring high pressure to be exerted from above the burial soil in order to crack. In usual conditions, this would correspond to a layer of soil over 20 m high, much higher than conditions that existed at the São Julião archaeological site.It was concluded that cockle shells studied in the present work were collected alive and probably consumed as food. Their fracturing was post-depositional, occurred during burial and was probably determined by the pressure exerted by a house of brick and cement that had existed above the archaeological site.

The Postmedieval Latvian Oral Microbiome in the Context of Modern Dental Calculus and Modern Dental Plaque Microbial Profiles.

Recent advantages in paleomicrobiology have provided an opportunity to investigate the composition of ancient microbial ecologies. Here, using metagenome analysis, we investigated the microbial profiles of historic dental calculus retrieved from archaeological human remains from postmedieval Latvia dated 16–17th century AD and examined the associations of oral taxa and microbial diversity with specific characteristics. We evaluated the preservation of human oral microbiome patterns in historic samples and compared the microbial composition of historic dental calculus, modern human dental plaque, modern human dental calculus samples and burial soil microbiota. Overall, the results showed that the majority of microbial DNA in historic dental calculus originated from the oral microbiome with little impact of the burial environment. Good preservation of ancient DNA in historical dental calculus samples has provided reliable insight into the composition of the oral microbiome of postmedieval Latvian individuals. The relative stability of the classifiable oral microbiome composition was observed. Significant differences between the microbiome profiles of dental calculus and dental plaque samples were identified, suggesting microbial adaptation to a specific human body environment.

Application of laser-induced breakdown spectroscopy and neural networks on archaeological human bones for the discrimination of distinct individuals

The use of elemental analysis based on Laser-Induced Breakdown Spectroscopy (LIBS) combined with Neural Networks (NN) is being evaluated as a method for assigning archaeological bone remains to individuals. The bone samples examined originate from excavations of burials at the Cross Street Unitarian Chapel, Manchester (United Kingdom) tha date from the 17th to the 19th century. In this study, we critically assess the influence of soil contaminants, by separating the bone elemental fingerprint into two groups of different components prior to the NN analysis. The first group includes elements related to the bone matrix (Ca and P) as well as elements that are regularly incorporated in the living bone tissues (Mg, Na, Sr, and Ba). The second group includes metals with a low probability of accumulation in living bone tissues whose presence is more likely to be related to diagenesis and the chemical composition of the burial soil (Al, Fe, Mn). The NN analysis of the spectral data, based on the use of an open access software, provided accurate results, indicating that it can be a promising tool for enhancing LIBS applications in osteoarchaeology. The influence of bone diagenesis and soil contaminants is significant. False classifications occurred exclusively in the NN analyses that relied partially on elemental peaks from the second group of elements. Overall, the present study indicates that discrimination between individuals through LIBS and NN analysis of bone material in an archaeological setting is possible, but a targeted approach based on selected elements is required and the influence of bone diagenesis will have to be assessed on a case-by-case basis. The proposed LIBS-NN method has potential as a tool capable for distinguishing distinct individuals in disarticulated or commingled human skeletal assemblages particularly if combined with standard osteometric methods.

The Effects of Rice Husk Ashes Filled Recycled Polyethylene Composites towards Physical, Mechanical Properties and Its Degradation Characteristics

Plastic waste is dominated by 46% Low Density Polyethylene (LDPE) and High Density Polyethylene (HDPE). The plastics waste are persistent pollutants that is not biodegradable waste. Recycled polyethylene (RP) from the plastic waste would potentially be used as polymer composites for pavement or road construction application. In order to improve physical, mechanical and water absorption properties, some fillers need to be added. The agro-industrial waste of rice husk ashes (RHA) containing highly silica SiO2 may be utilized as filler in this composites. The objective of this research is to observe the effect of RHA addition in to the recycled plastic composites towards its physical, mechanical properties and degradation characteristics. The RHA loading was designed weight/weight of RP as follows 0%; 5%; 10%; 15%; 20%, while degradation duration was 0, 30 and 60 days. The recycled ethylene was smelted and mixed with the RHA at temperature 120 o C; and then pressed using 200 kg.cm2 hydraulic press as pavement block (20x10x6 cm dimension). The results showed that the addition of RHA leads to increase the water absorption capacity, whereas it reduces the compressive strength. The RHA filler addition into composites has less significantly effects on thickness and surface-physical appearance (cracking profile). The 60 days degradation at ambient temperature with the sun lighting in a burial soil has a slight effect on the decreasing of compressive strength, thickness, and physical appearance (small crack on the surface) due to the thermal oxidative degradation. In addition, the burial soil exacerbate the bio-degradation mechanism due to the presence of high water absorbed within the RP-RHA composites. To sum up, the RHA may be potentially used as filler to improve water absorption capacity. Anti-oxidant and plasticizer types need to be researched to improve its physical mechanical properties.

Influence of natural factors on the biodegradation of simple and composite bioplastics based on cassava starch and corn starch

The massive use of petrochemical plastics has become a real problem for health and the environment. This problem is related to the non-biodegradable character of a great majority of these plastics and to the presence of certain chemical substances sometimes toxic in their internal structures. The development of biodegradable and less dangerous plastics thus represents an alternative to the petrochemical plastics. Two types of bioplastics were elaborated from cassava starch and corn starch. The simple bioplastics were obtained from starch only. The composite bioplastics were obtained by adding a natural ingredient extracted from the species Cola cordifolia to the starch. The biodegradability was assessed through burial tests in soil. The biodegradation was confirmed by the burial soil pH measurement. The burials in soil were also carried out taking into account the influence of abiotic (humidity, temperature) and biotic (enrichment in microorganisms) factors. The study showed that biodegradability of bioplastics is linked to the nature of the starch used. The simple cassava-based bioplastic degraded faster than those based on corn. The addition of the Cola cordifolia's natural ingredient, significantly improves the biodegradability of composite bioplastics compared to simple bioplastics. However, variability of environmental factors can improve or disadvantage biodegradability. Humidity promotes the biodegradability of bioplastics, especially composite bioplastics, up to a maximum rate of 15%. Enrichment in microorganisms is unfavourable beyond 10% enrichment for simple corn bioplastic and beyond 20% enrichment for composite and simple cassava-based bioplastics. The burial temperatures above 30 °C lead to a decrease in the biodegradability of bioplastics.

Metals and Environment: Chemical Outputs From the Interaction Between Gilded Copper-Based Objects and Burial Soil

Three-dimensional chemical mapping was adopted to investigate an ancient fire-gilded buckle found in Rome. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) were used to detect and locate degradation products aiming to identify the alteration processes. Inorganic and organic compounds present in the outermost part of such a class of cultural heritage objects can be considered the result of long-term interaction with the burial environment. ToF-SIMS depth profiling experiments can provide chemical information at the molecular level and high resolved spatial information (about 1 μm laterally, and 1 nm in depth). In this work, the attention was focused on the identification and localization of the ionic and molecular species involved in the degradation process. Results showed the presence of copper oxides, chlorides, and sulfides as common corrosion products but also the presence of species related to copper and bronze corrosion process such as atacamite and its polymorphs. 3D maps for all the relevant molecular species allowed to visualize at the same time the eruption of copper chlorides throughout the micro/nanochannels present on the gold surface, the recrystallization of compounds of minor elements from the substrate, a pathway followed by silico-aluminates from the surface towards the internal corrosion layers, but mostly the evidence of biological activity of Sulphur Reducing Bacteria (SRB) living in anaerobic conditions.

Seismic response of large diameter buried concrete pipelines subjected to high frequency earthquake excitations

Buried pipelines are tubular structures that cross large areas with different geological conditions. During an earthquake, imposed loads from soil deformations on pipelines may cause drastic damages. In this study two dimensional finite element models of pipelines and surrounding soils are used for simulation of seismic waves that propagate from the bedrock through the soil. The models describe both longitudinal and transverse cross-sections of pipelines and the soil-pipe interaction is described as a nonlinear behaviour. The effects of uniform ground with different burial depth and soil layer thickness, soil stiffness and non-uniform ground on the seismic response of reinforced concrete pipelines is studied. Two earthquakes, with high and low frequency contents, are employed for the dynamic analysis. The results show a significant effect on the response due to non-uniform ground caused by inclined bedrock, especially for high frequency earthquake excitations.

Analysis of the bacterial communities in ancient human bones and burial soil samples: Tracing the impact of environmental bacteria

In our attempts to reveal the hidden fragments of the history of the natural world, ancient DNA (aDNA) is the precious missing key that allows us to discover hidden truths about ourselves and the world around us. Not only does aDNA encrypt genetic data from a particular individual, it also carries information about the microbial communities that were present in the individual. However, the process of such data mining has many intrinsic challenges. One of the main challenges in aDNA research is the contamination of archaeological material with environmental bacteria from the surrounding soil and postmortem microbial sources.The goal of this study was to identify the microbial communities in human archaeological bone samples dated 15th - 17th century AD and to compare the microbiome patterns with the corresponding soil samples of the burial environment. Samples were analysed by 16S rRNA-based profiling of bacterial communities using Ion Torrent technology. The results showed that the most represented phyla in the bone samples were Firmicutes followed by Proteobacteria, Actinobacteria, Acidobacteria, Chloroflexi, Nitrospirae, Planctomycetes, Gemmatimonadetes and Bacteroidetes.All identified microbial taxa of the bone samples coincided with the corresponding soil samples, indicating significant infiltration and contamination of archaeological remains with microbial species of the burial environment. However, differences in microbial community composition between the bone and soil samples were observed at both the phylum and genus levels, as indicated by statistically significant beta-diversity analysis results. A deeper investigation of the Firmicutes phylum showed significant differences between the bone and soil samples by alpha- and beta-diversity analyses. Several genera belonging to Firmicutes were significantly more abundant in the soil samples than in the bone samples and vice versa.In conclusion, the analysis of the microbiome profiles of archaeological bone and corresponding soil samples revealed significant diversity in microbial compositions. It appeared that some bacteria may infiltrate the bone matter through the process of tissue decomposition and remain trapped inside for a longer period of time. Archaeological human bone samples might provide significant data on the investigation of ancient human microbiomes; however, environmental bacteria from the surrounding soil must be considered an important contamination factor.

Surface chromium on Terracotta Army bronze weapons is neither an ancient anti-rust treatment nor the reason for their good preservation

For forty years, there has been a widely held belief that over 2,000 years ago the Chinese Qin developed an advanced chromate conversion coating technology (CCC) to prevent metal corrosion. This belief was based on the detection of chromium traces on the surface of bronze weapons buried with the Chinese Terracotta Army, and the same weapons’ very good preservation. We analysed weapons, lacquer and soils from the site, and conducted experimental replications of CCC and accelerated ageing. Our results show that surface chromium presence is correlated with artefact typology and uncorrelated with bronze preservation. Furthermore we show that the lacquer used to cover warriors and certain parts of weapons is rich in chromium, and we demonstrate that chromium on the metals is contamination from nearby lacquer after burial. The chromium anti-rust treatment theory should therefore be abandoned. The good metal preservation probably results from the moderately alkaline pH and very small particle size of the burial soil, in addition to bronze composition.