Atmospheric Fallout Research Articles

Indoor microplastics and bacteria in the atmospheric fallout in urban homes

Humans may be exposed to microplastics (MPs) through food, drink, and air. Although several studies have examined indoor environmental MPs, none have yet compared atmospheric MP and bacterial deposition characteristics among rooms in homes. We investigated indoor airborne MPs and bacteria in five room types (bedroom, dining room, living room, bathroom, and study) based on the duration of usage of each room. We identified synthetic polymers (23,889 MP particles of 21 types) and bacterial communities (383 genera belong to 24 phyla) collected through atmospheric deposition in various rooms of 20 homes. The abundance and composition of MPs are related to the duration of usage, human activities, goods, cleanliness, and the composition of occupants (family members) in households. In addition, the homes of elderly families (age 68–81 years) showed higher bacterial concentrations than those of young families (age 28–35 years), indicating that age markedly affects the structure of household microbiota. Furthermore, a significant correlation between MP concentration and bacterial community structure was observed. The abundances of polyamide (PA), polyurethane (PU), and polyethylene (PE) showed positive correlations with the relative abundances of major bacterial phyla. Taken together, our results suggest that various rooms in the home exhibit distinct MP abundances and bacterial structures that may be affected by age, cleanliness, and human activities.

The Sedimentation Rate in the Crimean Hypersaline Lake Aktashskoye Estimated Using the Post-Chernobyl Artificial Radionuclide 90Sr as a Radiotracer

Artificial 90Sr is one of the most important long-lived radionuclides of global radioactive fallout from the atmosphere after the testing of nuclear weapons and the accident at the Chernobyl Nuclear Power Plant in 1986. In addition to fallout from the atmosphere, secondary radioactive contamination of Crimea was mainly from the Dnieper River and the North Crimean Canal, which occurred until 2014. 90Sr was used as the optimal radiotracer for estimating the rate of sedimentation in the Crimean hypersaline lake. Its vertical distribution in the bottom sediments was assessed. In the core of the bottom sediments, the detectable activity of 90Sr in layers 0–1.5 cm and 16.7–21.9 cm was absent, and it was determined again in the layer of 15.5 cm, which was associated with atmospheric fallout of the radionuclide after the Chernobyl NPP accident. There were well-isolated peaks of specific activity in layers at a depth of 4.6 and 13.3–14.3 cm. The calculated rate of sedimentation varied within 0.5–1.5 cm year−1: the minimum rate corresponded to the period 1971–2017, and the highest rate corresponded to the period 1954–1971.

The mass transfer of chemical elements and of their compounds in agrocenoses

The analysis of publications on the mass transfer of chemical elements in agrocenosis in the soil – plant system was carried out. Methods for estimating the content of mobile forms of chemical compounds coming from the soil into plants are considered. The phenomena of antagonism and synergism are characterized, and the necessity to consider them while planning fertilizer application is indicated. It is shown that the phenomena of synergism and antagonism of elements can be used in agriculture to regulate the flow of heavy metals or radionuclides into agricultural products. A balance model for mass transfer of chemical elements in agrocenosis is analyzed. It is shown that the introduction of organic fertilizers in soil mostly leads to a positive balance of microelements in the agrosystem. To characterize the efficiency of fertilizer use an assessment of the balance of nutrients in the agrosystem is required. The removal of trace elements by agricultural crops increases with the use of mineral fertilizers in doses that are optimal for the cultivation of crops in the region. In some cases, the input of heavy metals with technogenic fallout may exceed the removal of metals by plants from the soil. It may cause the accumulation of metals in the system. In uncontaminated background areas, the levels of microelement intake from fertilizers and atmospheric fallout in agrocenoses are comparable.

Late phase radiocesium dynamics in Fukushima forests post deposition

The long term dynamics of radiocesium in typical forest ecosystems was studied in the radioactive contaminated areas in Fukushima Prefecture. Six observations sites located in Yamakiya Village (Kawamata Town; since 2014), Tsushima Village (Namie Town, since 2015), and Tomioka Town (since 2017) were monitored. The forests consisted of artificial plantations of Japanese cedar (Cryptomeria japonica) at Yamakiya Village, Tsushima Village, and Tomioka Town. Tsushima Village also had a natural mixed forest dominated by Japanese red pine (Pinus densiflora), and Tomioka Town had a young and a mature artificial plantation of Japanese cypress (Chamaecyparis obtuse). Concentrations of 137Cs were monitored in the samples collected from the main aboveground biomass compartments, fresh litterfall, forest litter, and soil. Concentrations of exchangeable forms of 137Cs and stable K were measured in soil samples. During the observation period, the litter radiocesium inventories at all sites decreased significantly to approximately 1% or less of the total ground deposition. Approximately 80% of the total radiocesium inventory is localized in the upper 5-cm layer of soil and there is little downward migration of radiocesium. At the sites with the longest monitoring series (Yamakiya and Tsushima), the radiocesium expectation depths and expectation mass depths were relatively constant at 2–3 cm and 5–6 kg m−2, respectively. Aboveground biomass compartments showed similar decreasing trends in radiocesium aggregated transfer factors, Tag, in the compartments that were exposed to atmospheric fallout in March 2011 (old foliage, small branches, and outer bark). The mean Tag in cedar stand compartments currently are in the range of 10−3-10−2 m2 kg−1 dw. However, the mean Tag and their dynamic trend significantly differed in the wood compartments of the cedar stands, which may indicate root uptake differences of orders of magnitude between observation sites. The difference in radiocesium concentration in wood between the sites becomes less pronounced when normalized by the ratio of exchangeable 137Cs/K in the soils.

Research on the Physicochemical Properties of Fine Particulate Matter in Changchun, Northeast China

Objective: Air particulate matter concentrations in Changchun City, Jilin Province, may change around the autumn heating day. The aim of this study was to provide data references for environmental protection, detection and regulation in Changchun. Methods: Atmospheric particulate matter samples were collected using an airborne particulate matter sampler on the roof top of the Civil Engineering Teaching Hall on the campus of Jilin University of Construction; free settling dust of Atmospheric particulate matter was collected using metal trays. Atmospheric particulate matter concentrations were analysed by manual detection methods (weight method), carbonaceous fractions by total organic carbon analyser, and atmospheric fallout material composition and crystal structure by XRD diffractometer. The physicochemical properties of fine particulate matter around the autumn heating day in Changchun were investigated. Conclusions: (1) The daily average concentrations of various types of atmospheric particulate matter PM1, PM2.5 and PM10 generally increased after the start of the heating period. However, air quality is influenced by a combination of meteorological factors, of which emissions of air pollutants from urban heat generating plants during the heating period is only one aspect. So there is a situation where the average daily concentration of atmospheric particulate matter is lower after heating than before. (2) Analysis of the atmospheric its particulate matter PM2.5 samples collected around the heating day showed that the daily average concentrations of organic carbon (OC) and elemental carbon (EC) of atmospheric its particulate matter PM2.5 increased significantly after the heating day. (3) There was no significant difference in the main components of atmospheric dust fall before and after the heating day in Changchun, with the main components being crystalline SiO2 and a small Number of impurities.

SOIL AND ATMOSPHERIC AEROSOL CONTAMINATION AT THE TERRITORIES OF INFLUENCE OF FORMER URANIUM PRODUCTION FACILITIES “PRIDNIPROVSKY CHEMICAL PLANT”

Problems Statement and Purpose. The territory of the former Uranium production facility “Prydniprovsky Chemical Plant” (“PChP”) are located in Kamensky city, Dnipropetrovsk region, occupy the area of the upper and lower terraces of the Dnieper River (more than 300 hectares), where the remained legacy facilities and residues of the former uranium ore processing are located. After 1991 the production of Uranium concentrates ceased without remediated. Thus, up to 40 million tons of radioactive and chemical mineral residues of uranium production have accumulated within its industrial site and at the adjacent territories. Systemic monitoring studies began only in 2005. The studied environment characteristics were soils contamination, the tailings facilities where Uranium ore processing residues had accumulated, as well as atmospheric contamination by airborne aerosols. The purpose of this study stage is a comprehensive analysis of the spatial distribution of radionuclides of Uranium series at the legacy site territory and factors that can lead to a significant expansion of the contaminated area and scale of chronic environmental pollution under the influence of atmospheric transport and human exposure by inhalation. Data & Methods. The field sampling and analytical methods (gamma, alpha spectrometry and liquid scintillation counting methods) for determination of radionuclides of U-Th decay series were in use for this study. Soils samples from the top layers (0–5 cm) and gamma-dose rate surveys performed. A two-week continues integrated sampling data on the radioactive aerosols ambient activity concentrations and radioactive atmospheric fallout from 7-th locations at the legacy site and adjacent areas used for the environment radioactivity site-specific analyses. For determination of radionuclides in the environment samples (aerosols, soils and in the raw ore mineral residues) the low background gamma-spectrometry method with HPGe detectors have been in use. The content of metals associated with aerosols measured on filters using atomic absorption spectrometry methods. The data analysis for longterm series of observations (2005–2017) carried out using statistical methods. The compliance environment contamination analyses for the legacy site were carried comparing averaged observed data with the established safety criteria and regional background observation data. Results. The main current sources of radiation emission to the environment at the legacy site are open dispersed residues of Uranium production accumulated at the tailings facilities and at the former U‑extraction infrastructure. The spatial analyses of the gamma dose rate at the U‑production legacy site and its soil chemical contamination showed that about 30% of its territory requires decontamination. It is shown that the effects of aerosol radioactive particles dispersion from the contaminated “hot spots” at the territory such as tailings and former U‑production infrastructure are local and do not extend significantly beyond the industrial site. The greatest effects of wind re-suspension and propagation observed during the period of earthworks during construction of the U‑tailings covers and residues management at the contaminated facilities. In worst cases during earthwork at the U‑tailings facilities specific activity concentrations of 238U, 226Ra associated with aerosols (dust) nearby the tailings facilities may exceed 100 times above background radioactivity concentrations level observed at the distance about 10 km from the legacy site in the Kamyanske city. However, the air contamination with radioactive dusts in the worst meteorological conditions (dry windy period observation) did not exceed safe level of air concentrations according national radiation safety standards of Ukraine. The content of metals associated with aerosol particles can also increase by 2–10 times, but also their transfer by wind at the site is local and does not have a significant impact on residential areas of the city. Significant inhalation risks may arise during the dismantling of production equipment and buildings of former uranium production. Therefore, during implementation of any engineering remediation works, it is advisable to provide dust suppression control and to remove all dispersed materials from the former Uranium extraction before dismantling of the contaminated buildings and U‑production equipment. The introduced methods of air sampling at the PChP legacy site and low background analytical methods for radionuclide determination in the laboratories allow to recommend them for site specific environment monitoring programs bringing the radioactive contamination PChP site in a safe state

Distribution and characteristics of microplastics in beach sand near the outlet of a major reservoir in north Mississippi, USA

Plastic debris both affects and is affected by the beaches it accumulates on. Most studies of microplastics (MPs) in beach sand are focused on coastal beaches or beaches of large lakes near population centers. Here, we assessed MP pollution at a sandy beach near the outlet of a major flood control reservoir (Sardis Lake) in a relatively unpopulated area in north Mississippi, USA, focusing on two prominent wrack zones and areas in-between. Putative MPs were isolated by density separation and matrix digestion, and then examined using stereomicroscopy, with a subset of samples additionally analyzed by µ-FTIR. MP abundance (particles/kg ± 1 standard error (SE), n = 15) averaged of 590 ± 360, with 950 ± 100 in the lower wrack zone, 540 ± 40 in the upper wrack zone, and 270 ± 30 in areas between; these differences were statistically significant (p < 0.01). The MPs generally had similar size and shape characteristics across sites. The majority were fibers (64%), followed by fragments (23%), beads (7%) and films (6%), with a slightly greater proportion of fibers in the wrack zones compared to areas in-between. The number of MPs rose dramatically with decreasing size. Beads were only found in the < 500 µm size fraction. Clear and blue were the predominant colors for all MPs. A total of 29 different types of polymers were detected, with more than half of the particles being composed of polyethylene and polyamide, followed by poly(methyl methacrylate), polyethylene terephthalate, polycarbonate, polypropylene, and others; although this distribution varied some depending on size fraction and location. Because there are no major wastewater discharges into Sardis Lake, the source of the MPs is likely degradation of carelessly discarded plastic, as well as atmospheric fallout. Overall, we found that MP concentrations were highest in the wrack zones and influenced by rates and duration of discharge from the reservoir. Thus, like coastal beaches, wrack zones on freshwater beaches along or downstream of reservoirs accumulate both macro- and micro-plastics and are prime locations for plastic cleanup. Finally, we show that MPs made from naturally weathered LDPE plastic film are prone to fragmentation during pretreatment procedures, which may result in its overestimation.

Estimation of plutonium 241Pu budget in the Gulf of Gdańsk and the Gdańsk Basin (the southern Baltic Sea)

Presented have been the results of inventory estimation of anthropogenic beta-emitting 241Pu, in different components in the southern Baltic Sea ecosystem. The total 241Pu activity present in the Gulf of Gdańsk and the Gdańsk Basin for 2021 was estimated at 1.99 TBq and 7.82 TBq, respectively, of which 1.59 TBq and 6.38 TBq in the sediments. The Vistula and the Neman River and the atmospheric fallout were distinguished as the primary sources of plutonium in these basins. In seawater of the Gulf of Gdańsk, there was about 0.40 TBq 241Pu (20.1% of total activity) and 1.44 TBq 241Pu (18.4% of total activity) in the Gdańsk Basin. The 241Pu accumulated in living organisms in 2021 was 1.13 GBq in the Gulf of Gdańsk and 3.96 GBq in the Gdańsk Basin. In the Gulf of Gdańsk biota, 55.7% was accumulated in zoobenthos, while in the Gdańsk Basin, 48.3% was in zoobenthos.

Occurrence and human exposure risks of atmospheric microplastics: A review

Microplastics have attracted global attention as an emerging and ubiquitous contaminant in the environment. There are several pathways of human microplastic exposure, however, atmospheric microplastic pollution has yet rarely been elucidated systematically, especially the impact of atmospheric microplastics on human health. This review summarizes the current state of knowledge about microplastic pollution in atmosphere based on sample types, and the factors affecting microplastic transport or deposition as well as human exposure and potential risks on humans are discussed. Microplastics have been reported in suspended particular particles, atmospheric fallout, road dust and wet precipitation around the world, but the abundance of atmospheric microplastics varies in different regions. The abundance of microplastics in the atmosphere is greatly affected by human activities and meteorological factors, but the influence mechanisms on the transport and deposition processes remain to be clarified. Furthermore, atmospheric microplastics can pose potential health threats once inhaled, and the intake is age-related, with probably less intake for adults than children. Knowledge gaps and perspectives for further studies of atmospheric microplastic pollution status and human risk assessments are also proposed.

Suitability of surficial media for Ni–Cu–PGE exploration in an established mining camp: a case study from the South Range of the Sudbury Igneous Complex, Canada

A geochemical study over the southwestern part of the South Range of the Sudbury Igneous Complex was completed to assess the suitability of surficial media (humus, B-horizon soil and C-horizon soil) for delineating geochemical anomalies associated with Ni–Cu–PGE (platinum group element) mineralization. Another objective was to test whether Na pyrophosphate can eliminate the effects of anthropogenic contamination in humus. Results of this study suggest that the natural geochemical signature of humus is strongly overprinted by anthropogenic contamination. Despite no indication of underlying or nearby mineralization, metal concentrations in humus samples by aqua regia collected downwind from smelting operations are higher compared to background, including up to 13 times higher for Pt, 12 times higher for Cu and nine times higher for Ni. The high anthropogenic background masks the geogenic signal such that it is only apparent in humus samples collected in the vicinity of known Ni–Cu–PGE deposits. Results of this study also demonstrate that anthropogenically derived atmospheric fallout also influences the upper B-horizon soil; however, lower B-horizon soil (at &gt;20 cm depth) and C-horizon soil (both developed in till) are not affected. Glacial dispersal from Ni–Cu–PGE mineralization is apparent in C-horizon till samples analysed in this study. Compared to the background concentrations, the unaffected C-horizon till samples collected immediately down-ice of the low-sulfide, high precious metal Vermilion Cu–Ni–PGE deposit are enriched over 20 times in Pt (203 ppb), Au (81 ppm) and Cu (963 ppm), and over 30 times in Ni (1283 ppm). Supplementary material: supplementary tables and figures are available at https://doi.org/10.6084/m9.figshare.c.5691080

On the use of 210Pb-based records of sedimentation rates and activity concentrations for tracking past environmental changes

Lead-210 from natural atmospheric fallout is widely used in multidisciplinary studies to date recent sediments. Some of the 210Pb-based dating models can produce historical records of sediment accumulation rates (SAR) and initial activity concentrations (A0). The former have been profusely used to track past changes in the sedimentary conditions. Both physical magnitudes are differently affected by model errors (those arising for the partial or null accomplishment of some model assumptions). This work is aimed at assessing the effects on SAR and A0 of model errors in the CRS, CS, PLUM and TERESA dating models, due to random variability in 210Pb fluxes, which is a usual sedimentary condition. Synthetic cores are used as virtual laboratories for this goal. Independently of the model choice, SARs are largely affected by model errors, resulting in some large and spurious deviations from the true values. This questions their general use for tracking past environmental changes. A0 are less sensitive to model errors and their trends of change with time may reflect real changes in sedimentary conditions, as it is shown with some real cores from varved sediments.

ЭКОЛОГИЧЕСКИЙ МОНИТОРИНГ АТМОСФЕРНЫХ ОСАДКОВ (СНЕГА) В ЗАПОВЕДНИКЕ «БАСТАК»

In the paper, the authors consider the results of atmospheric fallout study in the Bastak nature reserve over a 10-year period. They show that the atmospheric air in the protected area is not polluted by natural or by anthropogenic impurities. Even single bursts of elevated concentrations of elements did not exceed either their background levels or permissible values.

Anthropogenic 236U and 233U in the Baltic Sea: Distributions, source terms, and budgets

The Baltic Sea receives substantial amounts of hazardous substances and nutrients, which accumulate for decades and persistently impair the Baltic ecosystems. With long half-lives and high solubility, anthropogenic uranium isotopes (236U and 233U) are ideal tracers to depict the ocean dynamics in the Baltic Sea and the associated impacts on the fates of contaminants. However, their applications in the Baltic Sea are hampered by the inadequate source-term information. This study reports the first three-dimensional distributions of 236U and 233U in the Baltic Sea (2018–2019) and the first long-term hindcast simulation for reprocessing-derived 236U dispersion in the North-Baltic Sea (1971–2018). Using 233U/236U fingerprints, we distinguish 236U from the nuclear weapon testing and civil nuclear industries, which have comparable contributions (142 ± 13 and 174 ± 40 g) to the 236U inventory in modern Baltic seawater. Budget calculations for 236U inputs since the 1950s indicate that, the major 236U sources in the Baltic Sea are the atmospheric fallouts (∼1.35 kg) and discharges from nuclear reprocessing plants (> 211 g), and there is a continuous sink of 236U to the anoxic sediments (589 ± 43 g). Our findings also indicate that the limited water renewal endows the Baltic Sea a strong "memory effect" retaining aged 236U signals, and the previously unknown 236U in the Baltic Sea is likely attributed to the retention of the mid-1990s' discharges from the nuclear reprocessing plants. Our preliminary results demonstrate the power of 236U-129I dual-tracer in investigating water-mass mixing and estimating water age in the Baltic Sea, and this work provides fundamental knowledge for future 236U tracer studies in the Baltic Sea.

Modelling the kinetic reactive transport of pollutants at the sediment-water interface. Applications with atmospheric fallout radionuclides

Understanding the behaviour of particulate matter and chemicals at the sediment-water interface (SWI) is of interest in environmental studies and risk assessments. These processes are still poorly understood, and this work aims to gain relevant insights by using a kinetic reactive transport model. It merges early diagenetic processes and box models for the uptake kinetics. Numerical solutions have been found for synthetic scenarios and for studying real cases from the literature (210Pb and Chernobyl fallout radionuclides in Lake Sniardwy, Poland, and 7Be in sediments from Tema Harbour, Ghana). The study identifies a series of factors that dynamically interact to govern the final fate of tracers in the SWI region, leading to a wide diversity of behaviours. When a term of eddy diffusivity is included in the upper regions of the pore fluid, which seems feasible for some energetic scenarios, it is possible to explain the observed large penetration depths for Cs and Be, while high particle-reactive elements are retained in thinner sediment layers. Desorption from the sediment occurs through the pore fluid as diffusive fluxes. Transient depth profiles of tracer concentrations can last from months up to a year, and they can show subsurface maxima at positions unrelated with the accretion rate. In the application cases, the model explained a wide set of observational data that was beyond the capabilities of other approaches involving physical mixing of solids and equilibrium kd. This modelling study could provide useful guidance for future research works.

Formation of Zn and Pb sulfides in a redox-sensitive modern system due to high atmospheric fallout

Human activities have led to a considerable increase in trace metal cycling in recent times. The mobilized elements get subjected to a variety of processes leading eventually to their re-concentration. The polluted sites, transformed by Earth's surface processes, become similar to metal accumulations known from geological records. This study examines authigenic metal sulfide mineralization in two peatlands polluted by atmospheric deposition from a nearby Pb-Zn smelter. We use the polluted peatlands as a small-scale model of Zn-Cd-Pb sulfide deposit to determine the role of organic matter in ore genesis and the textural and structural organization of biogenic precipitates.The study shows that the air-derived metal enrichment (up to 2.3 g Zn kg−1, 1.1 g Pb kg−1, and 62 mg Cd kg−1) is retained in a thin layer (∼30 cm) around 10–15 cm below the peat surface. A combination of focused ion beam (FIB) technology and scanning (SEM) and transmission (TEM) electron microscopy reveals that micrometric spheroids are most characteristic for ZnS and (Zn,Cd)S, although the sulfides readily form pseudomorphs after different plant tissues resulting in much larger aggregates. The aggregates have a complex polycrystalline sphalerite structure much more advanced than typically obtained during low-temperature synthesis or observed in other modern occurrences. Platy highly-disordered radially-aggregated submicrometre crystals develop within the time constraints of several decades in the cold (∼15 °C) and acid (pH 3.4–4.4) peat. The less abundant Pb sulfides occur as small cube-like crystals (<1µm) between ZnS or as flat irregular or square patches on plant root macrofossils. All PbS are crystalline and defect-free. Pb ion complexation with dissolved and solid organic matter is probably responsible for the low number and equilibrium shape of PbS crystals. Iron is absent in the authigenic sulfide mineralization and occurs entirely as organically bound ferric iron (Fe3+), as revealed by Mössbauer spectroscopy. The different affinity of metals to organic matter enhances the precipitation of Zn and Cd as sulfides over Pb and Fe. Our findings demonstrate that human activities lead to the formation of near-surface stratiform metal sulfide accumulations in peat, and the polluted sites can be of use to understand and reconstruct ancient ore deposits' genesis and mechanisms of formation.

Radiological hazard assessments of radionuclides in building materials, soils and sands from the Gaza Strip and the north of Sinai Peninsula

Radiological hazards to the residents of the Gaza Strip, Palestine and the north of the Sinai Peninsula, Egypt, were determined using the naturally occurring radionuclides (226Ra, 232Th and 40K) in 69 samples of building materials (demolition debris, plasters, concretes, from recycling plants and raw cements from suppliers), soils and sands collected in the field. The radiological hazard indices and dose rates calculated with the activity concentrations of radionuclides in those materials determined by gamma-ray spectrometry indicate that the values are all within the global limits recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation 2000 and European Commission 1999. The results of Spearman's correlation and hierarchical cluster analysis for 210Pb in the building materials, soils and sands suggest that the samples include 210Pb from the atmospheric fallout. The medium correlation between 232Th and 40K in demolition debris implies that their activity concentrations are characteristic of the building materials and constituents of the demolition debris. Non-natural ratio of 238U/235U was found in the soil and sand samples collected in the Gaza Strip. Furthermore, 137Cs and 241Am were detected in some soil, sand and demolition debris samples analyzed in this study. The origins of those anthropogenic radionuclides were considered.

Black Carbon and Its Effect on Carbon Sequestration in Soil

The properties of black carbon (BC) are described very differently in the literature, even when determined by the same methodological procedure. To clarify this discrepancy, BC was investigated in the clay Cambisols of southern Bohemia, Czech Republic, in groups of soils with lower and higher deposition of its atmospheric fallout. The BC determination was performed according to a modified method of Kuhlbusch and Crutzen (1995). The amount of the free light fraction, the occluded light fraction of soil organic matter and its ratio, the amount of heavy soil fraction DF, and its soil organic matter DFOM were determined. Other soil characteristics were identified. It was found that there are two very different types of BC in soils. Historical BC from biomass fires, and new, anthropogenic, from the furnace and transport fumes. Historical BC has a significant effect on the organic matter of the heavy soil fraction, on the ratio of the free and occluded soil organic matter fraction, and the number of water-resistant soil aggregates. Anthropogenic BC does not have this effect. Because this form of BC is not significantly stabilized by the colloidal mineral fraction, it is necessary to take general data on BC’s high stability and resistance to mineralization in the soil with circumspection.

Temporal change of 236U/238U and 235U/238U isotopic ratios in atmospheric deposition in Tokyo and Akita from 1963 to 1979

We examine the temporal changes of 236U/238U and 235U/238U in atmospheric deposition from samples collected in Tokyo and Akita from 1963 to 1979 and elucidate the spatial distribution and historical changes of the anthropogenic sources of uranium in Japan. The 236U/238U ratio of atmospheric deposition in Tokyo peaked in 1963 and again during the 1970s, while the corresponding 235U/238U ratios of atmospheric deposition during the second peak period were lower than that of natural uranium. The 236U/238U ratios of atmospheric deposition in Akita samples peaked in 1963. The 235U/238U ratios in Akita samples were almost identical to that of the natural uranium ratios. These results suggest that the peak of 236U/238U in 1963 corresponds to what is recognized as representative for global fallout. The increase of 236U/238U and the decrease of 235U/238U observed simultaneously in the 1970s indicate that depleted uranium has subsequently been released into the environment around Tokyo. The cumulative deposition density of 236U for atmospheric fallout samples collected in Tokyo from 1968 to 1979 is an order of magnitude larger than that of the global fallout, suggesting that the depleted uranium in the 1970s is a major component of 236U in Tokyo and should be considered as an end-member when using 236U as an environmental tracer in the industrial city. This knowledge can facilitate future research using 236U as an effective environmental tracer.

Geographical drivers of geochemical and mineralogical evolution of Motianling peatland (Northeast China) exposed to different sources of rare earth elements and Pb, Nd, and Sr isotopes

Geochemical shifts triggered by surface runoff and atmospheric fallout in a Chinese peatland were investigated by using Pb, Sr, and Nd, REE and by SEM mineralogical analysis. Motianling peatland (Northeast China) is located at 1670 m a.s.l., near the China–Mongolia border. Based on division of profile into two phases of different trophy, the total ∑REE value determined for the minerotrophic part of the profile (from 62 to 46 cm) varied from 67 to 31 mg·kg−1 and mineralogical analysis revealed the occurrence of weathered volcanic rocks, supported by a high εNd value (−3.26). After the transition from minerotrophic to more ombrotrophic conditions, the peatland became independent of the local bedrock weathering, which was manifested by a much lower concentration of REE (7–20 mg·kg−1) and lower εNd values (−7.37; −8.11). Moreover, PAAS-normalized pattern of REE distribution in the bottom part revealed the highest Eu/Eu* value (1.24), as well as a slight enrichment in Eu. The anthropogenic effect was visible from 1964, during which period the spheroidal aluminosilicate particles (SAP), produced by coal-fired power-plant activity, appeared for the first time, followed by an abrupt decrease in 206Pb/207Pb isotopic signature to 1.167. The dimensions of SAP (~1.5 μm), as well as the time of first appearance, indicated long-range transport. The REE ratios obtained in this study are characteristic of the eolian deposition signature, which is like the Gobi and northern Chinese deserts. The anthropogenic activity was manifested by a slight enrichment in Gd during reduced delivery of natural dust. Both, North Chinese and Asian part of the Russian industry supply anthropogenic dust. Topography, wind direction, and patterns of precipitation, as well as the initial phases of Asian industrial development, are the most important drivers promoting the deposition of chemical elements.

Organic Constituents and Biota in the Urban Atmospheric Solid Aerosol: Potential Effects on Urban Soils

The main components of solid atmospheric aerosol are soil and rock particles raised from the earth’s surface by wind erosion, and primary biological aerosol particles. In the composition of atmospheric aerosol, many pollutants, both mineral and organic, appear in areas with intensive human activity. Summer dust (solid atmospheric fallouts) that fell out of atmosphere was collected at two sites in Moscow (the territory of the Leo Tolstoy Museum-Estate in Khamovniki and the Botanical Garden of the Biological Faculty of Moscow State University). Morphological and microbiological studies were carried out in order to characterize the composition of the organic part of urban solid atmospheric fallouts and its possible impact on soils and the urban ecosystem as a whole. It has been found that the composition of the organic part of the samples was identical and included: the representatives of aeroplankton and other particles of biological origin, and also fragments of oil films, plastic fibers, carbon particles, etc., which indicated the hydrocarbon and microplastic pollution brought from the atmosphere. The composition of the studied groups of microorganisms in atmospheric fallouts and in urban soils was similar and indicated close ecological links between urban dust aerosol and soils. The biomass of the studied groups of microorganisms of atmospheric solids was dominated by fungi, many of which are potentially pathogenic and allergenic organisms. Apparently, atmospheric solid aerosols are carriers of microbiological pollution associated with animal feces in the city. The presence of such particles in the air indicates insufficient soil activity as a “bacterial filter”.