Geochemical Landscapes Research Articles

Evaluation of the geochemical background of soil in a hyper-arid zone using a multivariate statistical methodology: The case of the city of Antofagasta in the Atacama Desert

This study investigates the geochemical background and factors influencing the variability of 19 environmentally relevant elements in the soils of Antofagasta, Chile, a region known for its extensive mining activities. Employing robust multivariate statistical techniques on a dataset of 94 soil samples, we identified four main factors explaining 70% of the total variance in elemental concentrations. These four factors reflect the influence of Jurassic volcanic rocks, intrusive rocks, marine sediments, and mafic to intermediate intrusive rocks. Cluster analysis revealed three distinct geochemical populations, each reflecting a unique combination of natural and anthropogenic influences. We established background concentrations for each element within these clusters using robust statistical methods. Geostatistical analysis, employing inverse distance weighted interpolation, produced factor distribution maps that, when integrated with geological data, provided insights into lithological and anthropogenic influences on soil geochemistry. Our findings highlight the complex interplay between natural geological processes, the region's unique arid climate, and anthropogenic activities in shaping the geochemical landscape of Antofagasta. This study contributes to the understanding of geochemical backgrounds in mining-intensive, arid regions and provides a methodological framework applicable to similar environments worldwide.

Emergent ribozyme behaviors in oxychlorine brines indicate a unique niche for molecular evolution on Mars

Mars is a particularly attractive candidate among known astronomical objects to potentially host life. Results from space exploration missions have provided insights into Martian geochemistry that indicate oxychlorine species, particularly perchlorate, are ubiquitous features of the Martian geochemical landscape. Perchlorate presents potential obstacles for known forms of life due to its toxicity. However, it can also provide potential benefits, such as producing brines by deliquescence, like those thought to exist on present-day Mars. Here we show perchlorate brines support folding and catalysis of functional RNAs, while inactivating representative protein enzymes. Additionally, we show perchlorate and other oxychlorine species enable ribozyme functions, including homeostasis-like regulatory behavior and ribozyme-catalyzed chlorination of organic molecules. We suggest nucleic acids are uniquely well-suited to hypersaline Martian environments. Furthermore, Martian near- or subsurface oxychlorine brines, and brines found in potential lifeforms, could provide a unique niche for biomolecular evolution.

Investigations of Chemical Element Distributions in Soil, North Macedonia—A Review

This review article considers the following aspects: naturally distributed chemical elements and their enrichments, and the increased occurrence of PTEs due to anthropogenic and urban activities, as well as due to the geochemical uniqueness of certain geochemical landscapes, depending on the lithological environment. The review article is the result of many years of successful cooperation between the Geological Survey of Slovenia and the Faculty of Natural Sciences in Skopje, Ss. Cyril and Methodius University in Skopje, as well as several other institutions from North Macedonia, Russia and Romania but, also, through the voluntary and enthusiastic work of Prof. Trajče Stafilov’s PhD and Master’s students. To create the Geochemical Atlas, the territory of North Macedonia was covered with 995 sampling locations, but 16 separate areas with soil contamination were additionally sampled. The total sum of all collected soil samples was 3983 from 2449 different sampling sites in the period from 2006 to 2017. The analyses were performed at the Institute of Chemistry, Faculty of Natural Sciences in Skopje, at the Ss. Cyril and Methodius University in Skopje, North Macedonia, at the Research Institute for Analytical Instrumentation (ICIA), Cluj-Napoca, Romania, at the Joint Institute for Nuclear Research in Dubna, Moscow Region, Russia, and at Acme Labs in Vancouver, Canada. The sum of all analysed soil samples in all four mentioned laboratories was 7991 from 2006 to 2017. Using advanced mathematical methods such as multivariate statistical methods (HCA, FA, PCA) and artificial neural networks–multilayer perceptron (ANN-MP), predictions were made about the concentrations of potentially toxic elements (PTEs) and their distribution in real space. In less than two decades (2007–2023) of fruitful collaboration, a large number of scientific works have been published: 188 scientific publications, 8 geochemical atlases and 23 chapters in monographs.

Using iterative 2δ‐technique and 4δ‐outlier test for evaluating the geochemical background concentrations of trace elements in topsoil at Cao Bang province, Vietnam

AbstractThis study investigated the geochemical background values for seven trace elements in topsoil samples collected from highland areas within Cao Bang province, Vietnam. Total concentrations of these elements were determined, revealing the following order of mean concentration: Zn > Cr > Pb > Cu > As > Ni > Co. The background values were calculated using two different methods including iterative 2δ‐technique and 4δ‐outlier test. The 4δ‐outlier test yielded the following background concentrations (dry weight) for the seven elements: As (24.41 ± 12.42 mg kg−1), Co (15.64 ± 10.57 mg kg−1), Cr (49.31 ± 33.41 mg kg−1), Cu (29.77 ± 27.14 mg kg−1), Ni (22.52 ± 13.33 mg kg−1), Pb (38.06 ± 31.48 mg kg−1), Zn (71.79 61.09 mg kg−1). The 2δ‐technique, on the other hand, resulted in the following background concentrations (dry weight) for the same elements: As (8.41 ± 8.57 mg kg−1), Co (5.06 ± 4.31 mg kg−1), Cr (26.72 ± 26.20 mg kg−1), Cu (25.31 ± 24.81 mg kg−1), Ni (8.02 ± 7.83 mg kg−1), Pb (28.12 ± 27.58 mg kg−1), Zn (51.91 ± 49.44 mg kg−1). These results provide valuable baseline data for future environmental assessments and monitoring programs in the region. They also highlight the potential impact of human activities, such as mining, on the geochemical landscape of highland areas.

Geogas-Carried Metal Prospecting for Concealed Ore Deposits: A Review of Case Studies in China

Geogas-carried metal prospecting, an integral part of deep-penetrating geochemistry, is potentially effective in the geochemical exploration of concealed ore deposits. However, its principles and applicability remain controversial. This study summarizes and discusses the progress in geogas-carried metal prospecting in China. The method comprises three constituents: geogas, nanoparticles, and their vertical transportation. Researchers have failed to determine the exact contributions of different sources of geogas. Studies on Pb isotopes, rare earth element patterns of geogas, the comparisons between metals in soil, geogas, and ore geochemistry, and characteristics of nanoscale metals in earthgas (NAMEG), confirmed the relationship between NAMEG and concealed ore deposits. A statistical analysis of field experiments and applications showed that geogas-carried metal prospecting is applicable for the geochemical exploration of magmatic and hydrothermal Cu, Au, Zn, Pb, U, Sn, and Ag deposits and is suitable for most geochemical landscapes except deserts and cold swamps. Finally, genetic models of NAMEG anomalies were constructed. High-permeability migration channels are critical in the formation of NAMEG anomalies over concealed ore deposits. Future work entails applying geogas-carried metal prospecting to certain types of ore deposits and geochemical landscapes and studying NAMEG to provide quantitative information for targeting concealed ore deposits.

Agro-ecological processes under conditions of biogeochemical imbalance of molybdenum in agrolandscapes of the Forest-Step zone

A special place in the theory and practice of landscape geochemistry belongs to biogeochemical zoning. Biogenic migration of substances and chemical elements can rightfully be considered one of the criteria for the typological classification of geochemical landscapes, which is the basis for building a map of geochemical landscapes of Ukraine. The scientific result of zoning is the recognition of spatial boundaries and areas of the territory consisting of connected components with uniform conditions of geochemical migration of chemical elements. With a long-term violation of the ratio between microelements, various diseases appear, which are called endemic, and the phenomenon itself — biogeochemical endemics. The latter most often occur due to a lack or excess of some threshold value of the concentration of microelements or a violation of the ratio of other micro­elements associated with it. On the basis of landscape-geochemical analysis and zoning, the authors defined the territory of the biogeochemical provinces of the Forest Steppe, where a lack of molybdenum content in the soil for normal plant development was found. In addition, the features of the molybdenum province are determined by low biogenic accumulation and intensive physicochemical dispersion of essential trace elements, increased mobility of most toxic trace elements in natural waters, and the absence of conditions for the formation of barriers of hydroamphoteric elements, including Mo2+. Also, in the territories of biogeochemical provinces, there is a high probability of the development of certain endemic phytopathologies and microelement diseases due to the imbalance of biogeochemical food chains.

Geochemical landscapes as drivers of wildlife reproductive success: Insights from a high-Arctic ecosystem

The bioavailability of essential and non-essential elements in vegetation is expected to influence the performance of free-ranging terrestrial herbivores. However, attempts to relate the use of geochemical landscapes by animal populations directly to reproductive output are currently lacking. Here we measured concentrations of 14 essential and non-essential elements in soil and vegetation samples collected in the Zackenberg valley, northeast Greenland, and linked these to environmental conditions to spatially predict and map geochemical landscapes. We then used long-term (1996–2021) survey data of muskoxen (Ovibos moschatus) to quantify annual variation in the relative use of essential and non-essential elements in vegetated sites and their relationship to calf recruitment the following year. Results showed that the relative use of the geochemical landscape by muskoxen varied substantially between years and differed among elements. Selection for vegetated sites with higher levels of the essential elements N, Cu, Se, and Mo was positively linked to annual calf recruitment. In contrast, selection for vegetated sites with higher concentrations of the non-essential elements As and Pb was negatively correlated to annual calf recruitment. Based on the concentrations measured in our study, we found no apparent associations between annual calf recruitment and levels of C, Mn, Co, Zn, Cd, Ba, Hg, and C:N ratio in the vegetation. We conclude that the spatial distribution and access to essential and non-essential elements are important drivers of reproductive output in muskoxen, which may also apply to other wildlife populations. The value of geochemical landscapes to assess habitat-performance relationships is likely to increase under future environmental change.

Estimating the silica content and loss-on-ignition in the North American Soil Geochemical Landscapes datasets: a recursive inversion approach

A novel method of estimating the silica (SiO 2 ) and loss-on-ignition (LOI) concentrations for the North American Soil Geochemical Landscapes (NASGL) project datasets is proposed. Combining the precision of the geochemical determinations with the completeness of the mineralogical NASGL data, we suggest a ‘reverse normative’ or inversion approach to first calculate the minimum SiO 2 , water (H 2 O) and carbon dioxide (CO 2 ) concentrations in weight percent (wt%) in these samples. These can be used in a first step to compute minimum and maximum estimates for SiO 2 . In a recursive step, a ‘consensus’ SiO 2 is then established as the average between the two aforementioned SiO 2 estimates, trimmed as necessary to yield a total composition (major oxides converted from reported Al, Ca, Fe, K, Mg, Mn, Na, P, S and Ti elemental concentrations + ‘consensus’ SiO 2 + reported trace element concentrations converted to wt% + ‘normative’ H 2 O + ‘normative’ CO 2 ) of no more than 100 wt%. Any remaining compositional gap between 100 wt% and this sum is considered ‘other’ LOI and likely includes H 2 O and CO 2 from the reported ‘amorphous’ phase (of unknown geochemical or mineralogical composition) as well as other volatile components present in soil. We validate the technique against a separate dataset from Australia where geochemical (including all major oxides) and mineralogical data exist on the same samples. The correlation between predicted and observed SiO 2 is linear, strong ( R 2 = 0.91) and homoscedastic. We also compare the estimated NASGL SiO 2 concentrations with a sparser, publicly available continental-scale survey over the conterminous USA, the ‘Shacklette and Boerngen’ dataset. This comparison shows the new data to be a reasonable representation of SiO 2 values measured on the ground over the conterminous USA. We recommend the approach of combining geochemical and mineralogical information to estimate missing SiO 2 and LOI by the recursive inversion approach in datasets elsewhere, with the caveat to always validate results.

Correction to: Otolith Sr/Ca ratio complements Sr isotopes to reveal fish migration in large basins with heterogeneous geochemical landscapes

Correction to: Otolith Sr/Ca ratio complements Sr isotopes to reveal fish migration in large basins with heterogeneous geochemical landscapes

The Current State of Irrigated Soils in the Central Fergana Desert under the Effect of Anthropogenic Factors

This article highlights the role of anthropogenic factors in the modern and stage-by-stage development of soils, using the meadow-marsh soils of Central Fergana as an example. Information on the anthropogenic evolution of desert subtropical soils under long-term irrigation is provided. Data on the component composition of readily soluble salts in soils are discussed. It has been revealed that marsh-meadow soils under the influence of long-term irrigation gradually evolve into the irrigated meadow-saz soils of deserts. It is necessary to organize and conduct monitoring, the results of which could be implemented for the selection of agricultural crops, the development of methods of their sowing and planting, and for development of soil protection methods. In the initial period of using hydromorphic soils for irrigation in desert landscapes, there is a decrease in humus and total nitrogen content. The agrogenic transformation of hydromorphic soils under long-term and intensive use leads to significant changes in a number of soil properties. Each region-specific, soil-climatic condition may have its own pattern of soil areal evolution which is closely linked with the geochemical landscapes and the dynamics of the soil fertility. It is therefore necessary to consider the trends of soil transformation and evolution to improve soil fertility.

Single‐element Anomaly Mapping from Stream Sediment Geochemical Landscapes Aided by Digital Terrain Analysis

AbstractThe identification of anomalies within stream sediment geochemical data is one of the fastest developing areas in mineral exploration. The various means used to achieve this objective make use of either continuous or discrete field models of stream sediment geochemical data. To map anomalies in a discrete field model of such data, two corrections are required: background correction and downstream dilution correction. Topography and geomorphology are important factors in variations of element content in stream sediments. However, few studies have considered, through the use of digital terrain analysis, the influence of geomorphic features in downstream dilution correction of stream sediment geochemical data. This study proposes and demonstrates an improvement to the traditional downstream dilution correction equation, based on the use of digital terrain analysis to map single‐element anomalies in stream sediment geochemical landscapes. Moreover, this study compares the results of analyses using discrete and continuous field models of stream sediment geochemical data from the Xincang area, Tibet. The efficiency of the proposed methodology was validated against known mineral occurrences. The results indicate that catchment‐based analysis outperforms interpolation‐based analysis of stream sediment geochemical data for anomaly mapping. Meanwhile, the proposed modified downstream dilution correction equation proved more effective than the original equation. However, further testing of this modified downstream dilution correction is needed in other areas, in order to investigate its efficiency further.

Geochemical characteristics of Late Glacial and Holocene biogenic sediments in central Poland and implications for reconstructing the palaeoenvironment

The chemical composition of lake and mire sediments can be used as proxies of past changes in different accumulation environments. Here, I present these proxies that can be used to reconstruct the palaeoenvironment of the past 16,000 years for many mineral-biogenic series from central Poland and establish regional similarities and differences. Past geochemical studies of biogenic sediments from this region were usually carried out in the context of the genesis of: individual accumulation reservoirs, the development of the relief of river valleys and watersheds; they were also used in combination with other methods of palaeoecological research also reconstruct climatic changes in individual phases of the Late Glacial and Holocene. However, due to the complexity of matter circulation in the lithological and hypsometrical diverse transitional zone between the belts of the Polish Uplands and the Polish Lowlands, an analysis was made to determine the relationship between the conditions of biogenic sedimentation at individual sites using selected statistical analyses. In addition to its description of the geochemical variability of biogenic sediments, this analysis was supplemented by its reference to the spatial differentiation in the relationships between geochemical landscapes and the landforms of various orders. In turn, the method of lithogeochemical facies used for several profiles along the transect from the west to the east of the region made it possible to determine: the origin of water supplying the studied biogenic accumulation reservoirs, the range of individual zones of their supply and the conditions of inflow of allochthonous mineral matter.

СОДЕРЖАНИЕ РТУТИ В ПОЧВЕННЫХ БЕСПОЗВОНОЧНЫХ РЕКРЕАЦИОННОЙ ЗОНЫ КРУПНОГО ПРОМЫШЛЕННОГО ГОРОДА (Г. ЧЕРЕПОВЕЦ)

Soil invertebrates are the main food resource for birds and small mammals. The migration of mercury into the food webs of terrestrial ecosystems is still poorly investigated. The mercury content in soil, earthworms, wolf spiders and harvesters of the forest park zone of Cherepovets (Vologda region) was determined. The collection of the material was carried out on 5 sites (birch-aspen forest, wet pine forest, dry pine forest, wet meadow, dry meadow) differing in the composition of vegetation and the position in the cascade of geochemical landscapes. The minimum mercury content was found in the soils of the dry meadow (eluvial landscape) – 25 ng/g, the maximum – in the soils of the wet meadow (accumulative landscape) – 188 ng/g. The maximum concentrations of mercury in all sites were found in earthworms – from 261 ng/g in the dry pine forest to 1095 ng/g in the wet meadow. The concentration of mercury in wolf spiders was lower than in earthworms. The minimum values were found in a dry meadow. In all sites, the mercury content in wolf spiders was significantly higher than in harvesters. There are no significant correlations between the mercury content in soils and the organism of the studied invertebrates.

Nghiên cứu quá trình sinh địa hóa trong hệ thống “thảm thực vật – vật rơi rụng – đất” tại rừng nhiệt đới thuộc Vườn Quốc gia Bidoup-Núi Bà

The study of geochemical processes is an urgent task for understanding the functioning of the little-studied system "vegetation-litter-soil" and the biosphere as a whole. In mountainous areas, the processes of soil formation acquire unique features and are complicated by the processes of redistribution of matter. This work introduces the results of studies of geochemical processes in 2018-2022 on the territory of the Bidoup-Nui Ba National Park (Central Vietnam) during the wet and dry seasons. The influence of the relief on the formation of plant mortmass and the change in the ash content of fallen branches and leaves is considered. The results of studies of vertical and horizontal migration of chemical elements in soils of mid-mountain primary tropical monsoon forests are presented. Regularities of geochemical migration of chemical elements within all types of elementary geochemical landscapes, from autonomous to accumulative, are revealed. The existence in soils of several geochemical barriers characteristic of zheltozems has been revealed. The study made it possible to clarify the elements that are most actively involved in biogeochemical migration and accumulation in different seasons of the year, to assess the biogeochemical mobility of elements and the intensity of the processes of their biological accumulation by bamboo organs growing in different landscape conditions in the wet and dry seasons of the year. The research results make it possible to identify the features and patterns of changes in the content of trace elements in the "vegetation-litter-soil-soil" system, their biological accumulation and biogeochemical mobility during the wet and dry seasons in the Bidoup-Nui Ba National Park. The paper also presents the results of a study of soil samples for the presence of heavy metals, taken in the Bidoup-Nui Ba National Park. In the course of this study, native Cd contamination was detected in concentrations typical for objects subjected to technogenic pollution.

Modelling spatial uncertainty of geochemical anomalies using fractal and sequential indicator simulation methods

Mapping of geochemical anomalies is crucial to exploration and environmental geochemistry. The complex geochemical landscape, multiple geological sources and various secondary surficial processes impose a certain degree of spatial uncertainty in mapping of geochemical anomalies. Quantifying this uncertainty is significant for improving the efficiency of environmental monitoring or mineral prospecting. In this paper, sequential indicator simulation (SISIM) was used to assess local and spatial uncertainties of geochemical anomalies, and the concentration–area (C–A) fractal model was employed to determine the geochemical threshold prior to SISIM analysis. To illustrate the uncertainty of Ag geochemical anomalies, Ag concentration data of 1880 soil samples collected from NE of the Dong Ujimqin Banner district of Inner Mongolia, North China, was used in this study. Based on a set of simulation realizations of Ag concentrations, it was concluded that areas with low local (i.e. single-location) uncertainty of Ag concentrations entail low risk for mineral exploration. However, the spatial uncertainty for multi-locations showed that the joint probability statistics were stricter than local uncertainty. Therefore, combining local probability and spatial joint probability for delineating geochemical anomalies of Ag is more acceptable and reliable. The hybrid approach using the C–A fractal model and SISIM provides a new way to delineate anomalous areas by considering the uncertainty of spatial distributions of geochemical elements. Thematic collection: This article is part of the Applications of Innovations in Geochemical Data Analysis collection available at: https://www.lyellcollection.org/topic/collections/applications-of-innovations-in-geochemical-data-analysis

DISTRIBUTION AND MIGRATION OF CHEMICAL ELEMENTS IN THE MINOR RIVER BASINS IN THE WEST OF THE SMOLENSK-MOSCOW UPLAND AS AN INDICATOR FOR ASSESSING LANDSCAPE STABILITY

Hydrological objects link the landscape into connected basins of the paragenetic system through energy and matter migration. It determines the relevance of geochemical monitoring of minor river basins as a condition for designing an effective ecological framework for the territory. We tried to identify regularities of the spatial distribution and migration of chemical elements in the basins of minor rivers in the west of the Smolensk-Moscow Upland. The method of cross-spectrum geochemical analysis helped us to study the river basins of the Vop-Dnieper hydrological region. We compiled 47 complex landscape descriptions. Thus, the maximum calcium and movable magnesium cations values are determined in the super-aqual landscapes of the river basins under study. In the minor river valleys, we find outwash of organic compounds from the outer layers of the geochemical landscape. The research determines the maximum values of the studied elements in the soils of super-aqual landscapes through migration with subsurface and surface run-off. The minimum values are in the eluvial landscape, where there is a partial loss of geochemically movable forms of metals, which increases due to acid and weak-acid reactions of the environment. Partial outwash of metals, in particular copper and zinc, happens to organic compounds of soils. Trans-eluvial landscape loses trace elements. However, some of them are retained due to falling out of solutions and suspensions. Calculations have shown that copper (conjugation coefficient is 2–3) and zinc (conjugation coefficient is approximately 2) are most actively involved in the migration. In contrast, manganese is less active. The research results present an assessment of the features related to the landscape-geochemical differentiation of the territory of the west of the Smolensk-Moscow Upland from the upper areas of watersheds to the lower elements of landscape-geochemical catenae, including simple drainage basins of minor rivers. The research shows that the active migration of chemical elements characterizes the minor river basins. They are indicators of the geochemical state of the landscape. One can use the research results to assess a landscape-ecological condition, improve an environmental management system, and optimize the natural environment.

Geochemical features of the accumulation and migration of heavy metals in the peats of the Lviv region

Problem formulation. Study and interpretation of geochemical characteristic, component composition, content of macro- and microelements in peat has both a general scientific fundamental character and an applied one. Its results used for various purposes: quality assessment of peat, determination of the possibility of their use in industry etc. The article is devoted to study of the elements and microelements distribution in the peat of the Lviv region. The study of peatlands in western Ukraine and their component composition carried out only during geological exploration aimed at assessing the regions potential to produce own peat fertilizers or fuel. Article purpose. The aim of the work is to present an extended geochemical characteristic of Lviv’s region peats, to determine peats typical microelement composition and geochemical specialization, to establish regional regularities of distribution and accumulation of elements using methods of mathematical and statistical analysis, and to study the factors controlling the content, distribution and genesis of microelements in the region peatlands. Object, subject, factual material and research methods. The object of research is peat and its ash from peatlands of the Lviv region. The subject of research is geochemical characteristic of this peat, regional patterns of distribution and accumulation of chemical elements, components and geological and geochemical indicators in peats. The ashes of 248 peat samples taken in 110 representative areas were analyzed by spectral semi-quantitative analysis for the content of 21 chemical elements and other geochemical characteristics of peat (pH, ash content, etc.). Discussion. An integrated approach to the study of the geochemical characteristics of peat made it possible to identify the spatial geochemical features of peats in the territory of the Lviv region, to determine their typical microelements composition, to establish regional regularities of their distribution and accumulation (changes) - significant unevenness of the concentration of microelements by area of distribution, high indicators of the content of Mo, Yt, Sr, Co, Ag, Ba, Be, Pb in relation to the clarks of the lithosphere, soils, and plants. According to the results of correlation, factor and cluster analyzes, the following typomorphic geochemical associations of peats of the Lviv region can be distinguished: Ti-Ga-Cu-Y-Pb-Sc-V-Yb-Be is associated with the features of natural soil-forming processes of geochemical landscapes; Ni-Mo-Zn is possibly of technogenic origin and is associated with the accumulation of heavy metals in soils due to the development of mineral deposits. Conclusion. The analysis of the spatial distribution, mathematical and statistical processing of the geochemical characteristics and the composition and given varimax factor features and other integral and single-component parameters of peats described in the study indicates their satisfactory condition and can be to conclude that there is no regional pollution of peats in the Lviv region with heavy metals (except for Mo) or that the regional impact of such pollution is completely insignificant.

The Volchia Griva mineral oasis as unique locus for research of the mammoth fauna and the late Pleistocene environment in Northern Eurasia

AbstractThis paper describes the results of research at Volchia Griva, the largest site in Asia containing mammoth fauna in situ. It is situated in the south of the West Siberian Plain in the Baraba forest-steppe zone, and occupies an area of several hectares. Analysis of sediments and taphonomy of the site allows us to suggest that thousands of megafaunal remains were buried here in mud pits and erosional depressions. The favorable geochemical landscape of Volchia Griva attracted animals during periods of mineral starvation. This is reflected in the high mortality in two intervals, ca. 20–18 14C ka BP and ca. 17–11 14C ka BP. The results of palynological analysis of samples from the upper part of the Volchia Griva section made it possible to reconstruct the history of landscape changes of the Baraba Lowland during the MIS 2. Forb-mesophytic meadows were common at the beginning of this period, with taiga type forests. At ca. 20 14C ka BP, an abrupt and significant aridization of the climate occurred, which led to the degradation of forests. The mammoth steppe was widely developed, dominated by forb-grass association and with areas of alkali meadows and soils. Such conditions existed probably until the mid-Holocene.

Spatiotemporal Variations of Plague Risk in the Tibetan Plateau from 1954-2016.

Simple SummaryClimate variability has influence on plague outbreaks worldwide. Usually, plague cases increase with increasing precipitation. Currently there are many studies on the epidemics of plague in human beings, whereas there are few studies on the dynamic of plague in animal. Nevertheless, animal plague is key in the natural epidemiological cycle of plague. We identified spatiotemporal changes of the plague territories in the Tibetan Plateau only using animal plague records. Our risky plague maps are far superior to the county-based maps used currently and have valuable applications for directly informing conservation and management decisions locally and regionally.Plague persists in the plague natural foci today. Although previous studies have found climate drives plague dynamics, quantitative analysis on animal plague risk under climate change remains understudied. Here, we analyzed plague dynamics in the Tibetan Plateau (TP) which is a climate-sensitive area and one of the most severe animal plague areas in China to disentangle variations in marmot plague enzootic foci, diffusion patterns, and their possible links with climate and anthropogenic factors. Specifically, we developed a time-sharing ecological niche modelling framework to identify finer potential plague territories and their temporal epidemic trends. Models were conducted by assembling animal records and multi-source ecophysiological variables with actual ecological effects (both climatic predictors and landscape factors) and driven by matching plague strains to periods corresponding to meteorological datasets. The models identified abundant animal plague territories over the TP and suggested the spatial patterns varied spatiotemporal dimension across the years, undergoing repeated spreading and contractions. Plague risk increased in the 1980s and 2000s, with the risk area increasing by 17.7 and 55.5 thousand km2, respectively. The 1990s and 2010s were decades of decreased risk, with reductions of 71.9 and 39.5 thousand km2, respectively. Further factor analysis showed that intrinsic conditions (i.e., elevation, soil, and geochemical landscape) provided fundamental niches. In contrast, climatic conditions, especially precipitation, led to niche differentiation and resulted in varied spatial patterns. Additionally, while increased human interference may temporarily reduce plague risks, there is a strong possibility of recurrence. This study reshaped the plague distribution at multiple time scales in the TP and revealed multifactorial synergistic effects on the spreading and contraction of plague foci, confirming that TP plague is increasingly sensitive to climate change. These findings may facilitate groups to take measures to combat the plague threats and prevent potential future human plague from occurring.

Geochemical anomaly definition using stream sediments landscape modeling

Geochemical anomaly mapping is a crucial part of environmental and mineral exploration projects. Stream sediments are the most frequently sampling medium for geochemical mapping in regional scales, resulting from various geological processes. To enhance geochemical anomaly in stream sediments, the geochemical landscape, including topographic factors and drainage catchment basin extracted from a digital elevation model (DEM), and average precipitations, were applied. These factors were taken into consideration in this research to investigate the influence of the geochemical landscape constraints on the Mo polymetallic mineralization anomaly of stream sediments in a typical hilly area of Jining, Inner Mongolia, China, using Bayesian Maximum Entropy (BME) approach. Geographically weighted regression was applied to construct probability density function of soft data based on slope, aspect, drainage catchment basin and precipitation. Stream sediment data, at a scale of 1:200,000 (hard data), was integrated with the soft data to map stream sediment anomalies associated with molybdenum-polymetallic mineralization. Considering the influences of geochemical landscape during stream sediment anomaly identification can make up the shortage of missing and incomplete observations in regional geochemical data. By integrating the geochemical landscape factors during the stream sediment anomaly identification process, the impacts of the geochemical landscape on sediment dispersion halos were addressed, and the anomaly identification accuracy was improved. The anomaly areas defined by the BME model demonstrated that 31.41% of the study area contained 75% of the known mineral deposits and consequently the uncertainty of geochemical anomalies was reduced.