Redistribution Rates Research Articles

Methodology to address potential impacts of plastic emissions in life cycle assessment

PurposeProducts made of plastic often appear to have lower environmental impacts than alternatives. However, present life cycle assessments (LCA) do not consider possible risks caused by the emission of plastics into the environment. Following the precautionary principle, we propose characterization factors (CFs) for plastic emissions allowing to calculate impacts of plastic pollution measured in plastic pollution equivalents, based on plastics’ residence time in the environment.Methods and materialsThe method addresses the definition and quantification of plastic emissions in LCA and estimates their fate in the environment based on their persistence. According to our approach, the fate is mainly influenced by the environmental compartment the plastic is initially emitted to, its redistribution to other compartments, and its degradation speed. The latter depends on the polymer type’s specific surface degradation rate (SSDR), the emission’s shape, and its characteristic length. The SSDRs are derived from an extensive literature review. Since the data quality of the SSDR and redistribution rates varies, an uncertainty assessment is carried out based on the pedigree matrix approach. To quantify the fate factor (FF), we calculate the area below the degradation curve of an emission and call it residence time {tau }_{R}.Results and discussionThe results of our research include degradation measurements (SSDRs) retrieved from literature, a surface-driven degradation model, redistribution patterns, FFs based on the residence time, and an uncertainty analysis of the suggested FFs. Depending on the applied time horizon, the values of the FFs range from near zero to values greater than 1000 for different polymer types, size classes, shapes, and initial compartments. Based on the comparison of the compartment-specific FFs with the total compartment-weighted FFs, the polymer types can be grouped into six clusters. The proposed FFs can be used as CFs which can be further developed by integrating the probability of the exposure of humans or organisms to the plastic emission (exposure factor) and for the impacts of plastics on species (effect factor).ConclusionsThe proposed methodology is intended to support (plastic) product designers, for example, regarding materials’ choice, and can serve as a first proxy to estimate potential risks caused by plastic emissions. Besides, the FFs can be used to develop new CFs, which can be linked to one or more existing impact categories, such as human toxicity or ecotoxicity, or new impact categories addressing, for example, potential risks caused by entanglement.

Assessment of erosion rate in a rainfed agricultural area on the Northwestern coast of Egypt using 137Cs measurements

In the present work, the use of the fallout radionuclide 137Cs as a tracer for estimating soil redistribution rates over the past 60 years was tested in Egypt at an agricultural field with a smooth slope (0–10%) located in Ras El-Hekma on the Northwestern coast. The average annual soil erosion rate was derived from 137Cs inventories (Bq m−2) and by using the conversion Diffusion and Migration Model (DMM). The activity concentrations of 137Cs with uncertainty ranging between 7.5 and 20.9% were measured using HPGe gamma spectrometry. Approximately exponential shape for the distribution of 137Cs activity concentration was observed within the upper 20 cm of the soil profile associated with the reference site while for the study sites, the 137Cs depth distribution profiles indicate generally an increase of activity reaching a maximum peak of 137Cs usually at a depth of 10–15 cm followed by an abrupt exponential decrease of 137Cs activity concentration with depth. The measured average reference inventory for this area was 697 Bq m−2 with a coefficient of variation of 23%. This value is close to the estimated reference inventory using the conversion model, which was 744 Bq m−2. Transect sampling strategy was adopted at the study area where three parallel transects were chosen based on the common slope. The estimated average annual erosion rate for the three transects was found to be 7.5 t ha−1 y−1, and sediment delivery ratio was approximately 98%, which shows the moderate vulnerability of the Ras El-Hekma area to water erosion.

Practical considerations for feature assignment in high-speed AFM of live cell membranes.

High speed atomic force microscopy (HS-AFM) is, in principle, capable of yielding nanometer level detail about the surface of static structures. However, for highly dynamic samples HS-AFM may struggle with the correct feature assignment both within and between frames. Feature assignment in HS-AFM is dependent on (i) the intrinsic sampling rate, and (ii) the rate of internal redistribution of the sample. Whilst the first quantity (the sampling rate) is defined by the device parameters, the second quantity is frequently unknown, and is often the desired target of the measurement. This work examines how, even in the absence of gross cell morphological change, the rapid dynamics of living cell membranes, may impose an upper spatial limit to the frame-to-frame assignment of cell micro-topography and other related properties (such as local elasticity) whose motion may be described stochastically. Such a practical maximum may prove useful in the setup of HS-AFM experiments involving dynamic surfaces thereby facilitating selection of the most parsimonious relationship between observation size, image pixilation and sampling rates. To assist with performing the described calculations a graphical user interface-based software package called HS-AFM UGOKU is made freely available.

Effects of temperature and salinity on the sub-Antarctic snail Xymenopsis muriciformis (King and Broderip, 1832): Medium-term exposure to different climate change scenarios

As a consequence of climate change, benthic marine species that inhabit the sub-Antarctic oceans could be impacted as a result of changes in temperature and salinity that are affecting areas of high latitudes, where stenoic marine species are common. Therefore, the physiological performance of the species is essential to understand the ability of species to persist within their current range and to predict their rates of redistribution in response to the impacts of climate change impact. Xymenopsis muriciformis, an endemic sub-Antarctic benthic snail of the Strait of Magellan (53° 47′S; 70° 58′W), was used as a model species to understand the physiological response of a species that inhabits the Southern Oceans, where environmental conditions are very stable. We tested a medium-term exposure to the effects of climate change, including changes in temperature and salinity. The organisms were acclimatized for three months in the laboratory, at a temperature of 9 °C and salinity of 30 psu (control). The experiment was carried out for 60 days, where the ingestion rate and oxygen uptake were measured every 10 days. At the end of the experiments, the physiological condition of the organisms was determined by applying the metabolic indicators: carbohydrate indices (CHI), total lipids (TLI) and lipofuscins (LI), which were obtained by histological-histochemical analysis. The results indicated that temperature had significant effects on the ingestion rate and oxygen consumption, while salinity and the interaction between salinity and temperature had no significant effects. Organisms exposed to low temperatures (1 °C) and (5 °C), expected for the southern hemisphere summer, exhibited cellular degradation, which would limit the access and colonization of Antarctic environments. The organisms exposed to the 15 °C treatment (expected for the Magellan region), presented a significantly higher amount of lipofuscins in the vesicular connective tissue cells with morphological characteristics in the autophagosomes. We concluded that the snail X. muriciformis is a characteristic stenoic species, highly sensitive to temperature variations, as those projected in climate change scenarios for the Antarctic and sub-Antarctic regions.

High-Voltage Nanosecond Discharge as a Means of Fast Energy Switching

The formation of a nanosecond discharge with the use of a Hamamatsu streak-camera and with simultaneously wideband (10 GHz) measurement of voltage and displacement current caused by a streamer in one pulse has been studied. Nanosecond voltage pulses of various amplitudes (16, 20, and 27 kV) were applied across a point-to-plane gap (8.5 mm) filled with air at various pressures (13, 25, 50, 100, and 200 kPa). It was found that the voltage across the gap drops as soon as a streamer appears in the vicinity of the pointed electrode. At the same time, a pre-breakdown current begins to flow. The magnitude of the pre-breakdown current, as well as the voltage drop, is determined by the rate of formation of dense plasma and, accordingly, by the rate of redistribution of the electric field in the gap. The streamer velocity determines the rise time and amplitude of the current. The higher the streamer velocity, the shorter the rise time and the higher the amplitude of the pre-breakdown current. The propagation of a backward and third ionization waves was observed both with the streak camera and by measuring the displacement current. As they propagate, the discharge current increases to its amplitude value.

Impacts of Landscape Evolution on Heterotrophic Carbon Loss in Intensively Managed Landscapes

Soil respiration that releases CO2 into the atmosphere roughly balances the net primary productivity and varies widely in space and time. However, predicting its spatial variability, particularly in intensively managed landscapes, is challenging due to a lack of understanding of the roles of soil organic carbon (SOC) redistribution resulting from accelerated soil erosion. Here we simulate the heterotrophic carbon loss (HCL)—defined as microbial decomposition of SOC—with soil transport, SOC surface redistribution, and biogeochemical transformation in an agricultural field. The results show that accelerated soil erosion extends the spatial variation of the HCL, and the mechanical-mixing due to tillage further accentuates the contrast. The peak values of HCL occur in areas where soil transport rates are relatively small. Moreover, HCL has a strong correlation with the SOC redistribution rate rather than the soil transport rate. This work characterizes the roles of soil and SOC transport in restructuring the spatial variability of HCL at high spatio-temporal resolution.

Forest fires and climate-induced tree range shifts in the western US

Due to climate change, plant populations experience environmental conditions to which they are not adapted. Our understanding of the next century’s vegetation geography depends on the distance, direction, and rate at which plant distributions shift in response to a changing climate. In this study we test the sensitivity of tree range shifts (measured as the difference between seedling and mature tree ranges in climate space) to wildfire occurrence, using 74,069 Forest Inventory Analysis plots across nine states in the western United States. Wildfire significantly increased the seedling-only range displacement for 2 of the 8 tree species in which seedling-only plots were displaced from tree-plus-seedling plots in the same direction with and without recent fire. The direction of climatic displacement was consistent with that expected for warmer and drier conditions. The greater seedling-only range displacement observed across burned plots suggests that fire can accelerate climate-related range shifts and that fire and fire management will play a role in the rate of vegetation redistribution in response to climate change.

Evolutionary constraints on physiology confound range shift predictions of two nacellid limpets

Physiological comparisons are fundamental to quantitative assessments of the capacity of species to persist within their current distribution and to predict their rates of redistribution in response to climate change. Yet, the degree to which physiological traits are conserved through evolutionary history may fundamentally constrain the capacity for species to adapt and shift their geographic range. Taxa that straddle major climate transitions provide the opportunity to test the mechanisms underlying evolutionary constraints and how such constraints may influence range shift predictions. Here we focus on two abundant and shallow water nacellid limpets which have representative species on either side of the Polar front. We test the thermal thresholds of the Southern Patagonian limpet, Nacella deaurata and show that its optimal temperatures for growth (4 °C), activity (-1.2 to -0.2 °C) and survival (1 to 8 °C) are mismatched to its currently experienced annual sea surface temperature range (5.9 to 10 °C). Comparisons with the congeneric Antarctic limpet, N. concinna, reveal an evolutionary constraint on N. deaurata physiology, with overlapping thermal capacities, suggesting that a cold climate legacy has been maintained through the evolution of these species. These physiological assessments predict that the South American range of N. deaurata will likely decline with continued warming. It is, however, one of the first species with demonstrated physiological capacity to successfully colonize the cold Southern Ocean. With the expected increase in opportunities for transport within high southern latitudes, N. deaurata has the potential to establish and drive ecological change within the shallow Southern Ocean.

10Be and 14C data provide insight on soil mass redistribution along gentle slopes and reveal ancient human impact

PurposeSpatial and temporal patterns of past erosional events are a useful and needed information to explain observed soil patterns in different landscapes. Soil thickness reflects the overall expression of pedogenesis and erosion. Forested soils of Northern Germany exhibit varying soil thicknesses with thin soils on crest positions and buried soils at the footslope. The aim of this study is to reconstruct the complex soil mass redistribution and soil patterns of this forested area due to different periods of erosion and stability.MethodsWe explored the explanatory power of both 10Be (in situ and meteoric) on a hillslope and we 14C-dated buried horizons at different depths.ResultsThe 10Be depth profiles did not show an exponential decrease with depth. They had a ‘bulge’ shape indicating clay translocation and interaction with oxyhydroxydes (meteoric 10Be), bioturbation and soil mass redistribution (in situ 10Be). The combined application of both 10Be and 14C dating revealed progressive and regressive phases of soil evolution. Although Melzower Forest is protected (same vegetation) since the past 250 years, both 10Be clearly indicated major soil mass redistribution along the investigated catena.ConclusionA strong erosion impulse must have occurred between 4.5 and 6.8 kyr BP indicating an earlier human impact on soil erosion than previously postulated (~ 3 kyr earlier). Our findings correlate in fact with the first settlements reported for this region (~ 6.8 kyr BP) and show their immediate effect on soils. The overall soil redistribution rates in this forest are surprisingly similar to those obtained from a nearby agricultural area.

Brain Doppler abnormalities in fetuses with open spina bifida

Background To describe the brain Doppler changes in fetuses with isolated open spina bifida (OSB). Study design Doppler ultrasound measurements including the umbilical artery (UA) pulsatility index (PI), middle cerebral artery (MCA) PI, and their combination into the cerebroplacental ratio (CPR) and umbilicocerebral ratio (UCR) were performed in a cohort of fetuses with OSB. Included patients were individually matched to a control group without structural anomalies and similar gestational ages. MCA-PI and/or CPR values below the 5th centile were considered abnormal and indicative of cerebral blood redistribution, while UCR and UA-PI above the 95th centile were considered abnormal. Results During the study period, 266 fetuses were recruited, 133 normally grown fetuses with OSB and 133 matched controls. Doppler recordings were successfully obtained in all fetuses at a median gestational age of 30.9 weeks. All cases showed UA-PI within normal ranges, but fetuses with OSB showed significantly higher frequency of cerebral blood redistribution (15.0 vs. 3.0%, p < .01), MCA-PI <5th centile (10.5% vs. 3.0%, p = .01), decreased CPR (9.8% vs. 2.3%, p = .01) and increased UCR (17.2 % vs 7.5 %, p =.02). The rate of cerebral blood redistribution was significantly higher in the OSB group with ventriculomegaly in comparison to those with OSB and normal lateral ventricle diameter (18.6% vs. 3.2%, respectively; p <.05). Conclusion A proportion of fetuses with isolated open spina bifida showed cerebral blood redistribution.

Investigation of the effect of anthropogenic land use on the Pănăzii Lake (Romania) catchment area using Cs-137 and Pb-210 radionuclides.

The problem of soil degradation has accentuated over recent decades. Aspects related to soil erosion and its relation to changes in land use as well as anthropogenic influence constitute a topic of great interest. The current study is focused on a soil erosion assessment in relation to land use activities in the Pănăzii Lake catchment area. Fallout radionuclides were used to provide information on soil erosion as well as redistribution rates and patterns. Variations in the sedimentation rate of the lake were also investigated as these reflect periods in which massive erosion events occurred in the lake catchment area. The novelty of this study is the construction of a timescale with regard to the soil erosion events to better understand the relationship between soil erosion and land use activities. In this study, 10 soil profiles and one sediment core from the lake were taken. Soil parameters were determined for each sample. The activities of 210Pb, 137Cs and 226Ra were measured by gamma spectroscopy. For low 210Pb activities, measurements via 210Po using an alpha spectrometer were performed. Soil erosion rates were determined by the 137Cs method and the sedimentation rate calculated by the Constant Rate of Supply (CRS) model. A soil erosion rate of 13.5 t·ha-1·yr-1 was obtained. Three distinct periods could be observed in the evolution of the sedimentation rate. For the first period, between 1880 and 1958, the average deposition rate was 9.2 tons/year, followed by a high deposition period (1960–1991) of 29.6 tons/year and a third period, consisting of the last 30 years, during which the sedimentation rate was 15.7 tons/year. These sedimentation rates fluctuated depending on the main land use activity, which can also be seen in the soil erosion rates that had almost doubled by the time agricultural activities were performed in the area.

Parameter estimation in fluorescence recovery after photobleaching: quantitative analysis of protein binding reactions and diffusion

Fluorescence recovery after photobleaching (FRAP) is a common experimental method for investigating rates of molecular redistribution in biological systems. Many mathematical models of FRAP have been developed, the purpose of which is usually the estimation of certain biological parameters such as the diffusivity and chemical reaction rates of a protein, this being accomplished by fitting the model to experimental data. In this article, we consider a two species reaction–diffusion FRAP model. Using asymptotic analysis, we derive new FRAP recovery curve approximation formulae, and formally re-derive existing ones. On the basis of these formulae, invoking the concept of Fisher information, we predict, in terms of biological and experimental parameters, sufficient conditions to ensure that the values all model parameters can be estimated from data. We verify our predictions with extensive computational simulations. We also use computational methods to investigate cases in which some or all biological parameters are theoretically inestimable. In these cases, we propose methods which can be used to extract the maximum possible amount of information from the FRAP data.

Impacts of oak deforestation and rainfed cultivation on soil redistribution processes across hillslopes using 137Cs techniques

BackgroundAs one of the main components of land-use change, deforestation is considered the greatest threat to global environmental diversity with possible irreversible environmental consequences. Specifically, one example could be the impacts of land-use changes from oak forests into agricultural ecosystems, which may have detrimental impacts on soil mobilization across hillslopes. However, to date, scarce studies are assessing these impacts at different slope positions and soil depths, shedding light on key geomorphological processes.MethodsIn this research, the Caesium-137 (137Cs) technique was applied to evaluate soil redistribution and soil erosion rates due to the effects of these above-mentioned land-use changes. To achieve this goal, we select a representative area in the Lordegan district, central Iran. 137Cs depth distribution profiles were established in four different hillslope positions after converting natural oak forests to rainfed farming. In each hillslope, soil samples from three depths (0–10, 10–20, and 20–50 cm) and in four different slope positions (summit, shoulder, backslope, and footslope) were taken in three transects of about 20 m away from each other. The activity of 137Cs was determined in all the soil samples (72 soil samples) by a gamma spectrometer. In addition, some physicochemical properties and the magnetic susceptibility (MS) of soil samples were measured.ResultsErosion rates reached 51.1 t·ha− 1·yr− 1 in rainfed farming, whereas in the natural forest, the erosion rate was 9.3 t·ha− 1·yr− 1. Magnetic susceptibility was considerably lower in the cultivated land (χhf = 43.5 × 10− 8 m3·kg− 1) than in the natural forest (χhf = 55.1 × 10− 8 m3·kg− 1). The lower soil erosion rate in the natural forest land indicated significantly higher MS in all landform positions except at the summit one, compared to that in the rainfed farming land. The shoulder and summit positions were the most erodible hillslope positions in the natural forest and rainfed farming, respectively.ConclusionsWe concluded that land-use change and hillslope positions played a key role in eroding the surface soils in this area. Moreover, land management can influence soil erosion intensity and may both mitigate and amplify soil loss.

Redistribution of chlorides in concrete specimens occurring during storage

It has been observed that storage of specimens with chloride gradients before determining the chloride profile can lead to changes in the shape of the chloride profile. An experimental study to quantify the influence of the duration of the storage period and the storage temperature has been carried out. It comprised three storage periods (7, 28 and 91 days) and two storage temperatures (+ 5 °C and + 20 °C). The specimens had previously been immersed in a 15% NaCl solution for 56 days and were sealed in plastics during storage. The results show that a temperature of + 5 °C diminishes the rate of redistribution considerably, compared to a storage carried out at + 20 °C, and the longer the storage period is, the more redistribution will take place. It is also shown that it is of importance to assure that the sealing of the specimens during storage is capable of maintaining the relative humidity at the surface, so that local redistribution of chlorides close to the surface will not take place.

Introduced alien, range extension or just visiting? Combining citizen science observations and expert knowledge to classify range dynamics of marine fishes

AbstractAimDespite the unprecedented rate of species redistribution during the Anthropocene, there are few monitoring programmes at the appropriate spatial and temporal scale to detect distributional change of marine species and to infer climate‐ versus human‐mediated drivers of change. Here, we present an approach that combines citizen science with expert knowledge to classify out‐of‐range occurrences for marine fishes as potential range extensions or human‐mediated dispersal events.InnovationOur stepwise approach includes decision trees, scoring and matrices to classify citizen science observations of species occurrences and to provide a measure of confidence and validation using expert knowledge. Our method draws on peer‐reviewed literature, knowledge of the species (e.g. contributing to its detectability, and potential to raft with, or foul, man‐made structures or debris) and information obtained from citizen science observations (e.g. life stage, number of individuals). Using a case study of suspected out‐of‐range marine fishes in Aotearoa New Zealand, we demonstrate our approach to defining species’ ranges, assigning confidence to these definitions and considering the species detectability to overcome the data deficiencies that currently hinder monitoring the range dynamics of these species. Our classification of citizen science observations revealed that six of ten species had out‐of‐range occurrences; one of these was classified as an extralimital vagrant, four species had potentially extended their ranges and one species occurrence was likely due to human‐mediated dispersal.ConclusionThe case study of marine fishes in New Zealand validates our approach combining citizen science observations with expert knowledge to infer species range dynamics in real time. Our stepwise approach helps to identify data deficiencies important in informing scientific inferences and management actions and can be refined to suit other data sources, taxonomic groups, geographic settings or extended with new steps and existing tools.

Climate-Driven Range Shifts Are Rapid Yet Variable Among Recreationally Important Coastal-Pelagic Fishes

Shifts in species distributions are occurring globally in response to climate change, but robust comparisons of redistribution rates among species are often prevented by methodological inconsistencies, challenging the identification of species that are most rapidly undergoing range shifts. In particular, comparable assessments of redistributions among harvested species are essential for identifying climate-driven changes in fishing opportunities and prioritising the development of management strategies. Here we utilise consistent datasets and methodologies to comparably analyse rates of climate-driven range shifts over 21 years for four recreationally important coastal-pelagic fishes (Australian bonito, Australian spotted mackerel, narrow-barred Spanish mackerel, and common dolphinfish) from the eastern Australian ocean warming hotspot. Latitudinal values corresponding to the poleward edge of species’ core oceanographic habitats were extracted from species distribution models (SDMs). Rates of poleward shifts in core oceanographic habitats ranged between 148.7 (i.e., common dolphinfish) and 278.6 (i.e., narrow-barred Spanish mackerel) km per decade over the study period. However, rates of redistribution varied by approximately 130 km per decade among species, demonstrating that subtle differences in species’ environmental responses can manifest in highly variable rates of climate-driven range shifts. These findings highlight the capacity for coastal-pelagic species to undergo rapid, yet variable, poleward range shifts, which have implications for ecosystem structure and the changing availability of key resources to fisheries.

On Trade, Distributional Conflict, and Endogenous Regime Change

Can we expect shocks in trade openness to affect the quality of the domestic political process, and in what way? Isolating cross-country heterogeneity in the distributional effects of trade shocks for different relative factor endowments as a critical element for theory development, the paper tackles the puzzle by formally developing and solving a new probabilistic model to link the distributional effects of shocks to endogenous institutional change via induced conflict between a capital-intensive and a labour-intensive coalition. The model of distributional conflict combines a political selection stage to select the rate of income redistribution by majority voting and a constitutional conflict stage among factor-intensive coalitions whose steady state outcome determines the level of institutional inequality assigning the “rules“ of political selection. The former is modelled via a canonical weighted median voter setup with the (infinitely many) weights-distributions induced by the value of the steady state outcome of the constitutional conflict stage, while the latter is modelled as a Tullock contest with an endogenous contest success function and the heterogeneous coalition prizes equalling the expected value of the contest to each coalition as a function of the coalitions' efforts. Closed form solutions are derived for (i) the expected outcome of distributional conflict in terms of institutional quality and (ii) the intensity of conflict. Via comparative static analysis based on the Stolper Samuelson theorem in Heckscher-Ohlin trade theory, it is formally shown that positive shocks in trade openness always induce higher institutional inequality irrespective of heterogeneity in the underlying distributional effects, but that the expected mechanisms driving the drop in quality differ across capital-abundant and labour-abundant countries.

PIV study of directional solidification of a binary metal alloy analogue

Flows driven by double-diffusive convection during alloy solidification strongly influence the macroscopic solute redistribution, localized remelting and solidification rates which play a dominant role in determining the mechanical, electrical and thermal properties of the final product. This experimental study is carried out to investigate the effect of initial concentration and initial cavity height on the development of double-diffusive convection and on the real-time solidification interface growth during solidification of aqueous sodium chloride solution in a top-cooled rectangular cavity. Aqueous sodium chloride solution is widely used as an analogues model system for most of the alloys to study their solidification behaviour because of its transparency that enables the flow visualization using optical techniques. In the present work, particle image velocimetry (PIV) method is used for the velocity measurement during solidification. PIV measurements show that on increasing the initial concentration and the initial cavity height, the strength of the convection flow increases. The evolution of solidification is also captured using a high-speed (HS) camera. The images captured during solidification indicates that the wavy interface formed due to remelting phenomena caused by double-diffusive convection. Further, we also noticed that the solidification rate decreases by increasing the initial concentration and decreasing the initial cavity height.

In English

Nowadays nanocomposites based on magnetite doped with noble metal cations or core&amp;shell type nanocomposites including superparamagnetic core and precious metal shells are widely used in new kinds of biocompatible materials creation. The following structures are characterized by unique complexes of physical-chemical properties. The noble metal coatings formed on the magnetite nanoparticles surface supply their corrosive biological media stabilization and effects on electrical, magnetic, catalytic, optical properties of core&amp;shell type nanocomposites as well. This work studies the effect of UV irradiation (253 nm) on the paramagnetic characteristics of biocompatible core&amp;shell type nanocomposites based on magnetite and precious metals (silver, gold). Nanoparticles of magnetite and core&amp;shell type composites Fe3O4&amp;Ag0 and Fe3O4&amp;Au0 were formed under the rotation-corrosion dispergation conditions on the steel 3 (St3) surface contacting with distilled water and aqueous solutions of silver nitrate and tetrachloroauric acid at a free flow of oxygen into the reaction zone. Solutions of precious metals contained from 0.5 to 20 mg/dm3 of Ag(I) and Au(III) aquaforms. The composite nanoparticles were characterized using X-ray diffraction data, scanning electron microscopy and electron paramagnetic resonance spectroscopy. Because of expecting photocatalytic activity of as-prepared nanocomposites, we performed their illumination by ultraviolet irradiation. The effect of UV irradiation (253 nm) on the paramagnetic characteristics of biocompatible core&amp;shell nanocomposites based on magnetite and precious metals (silver, gold) was studied by EPR analysis. The obtained data suggests that after UV irradiation the contribution of Fe2+ spins increases, the band gap for Fe3O4 decreases, the rate of charge redistribution at the oxide-metal interface increases, the number of spins in the composite increases. The study of the occurrence of paramagnetic centers mechanism in the nanocomposites based on magnetite and precious metals may be relevant for determining their bactericidal and photocatalytic activity. Also, such nanocomposites can be used in the creation of technical means for prevention of the spread of infectious diseases in the transport, public places, and hospitals.

Analysis and technology to reduce the impact of tailings on the ecology of local water bodies

An integral part of the technological chain in the processing of uranium ores is a tailing dump designed for organizational disposal and long-term storage of tailings. There are up to 170 production and monitoring wells around the tailings for comprehensive monitoring of the impact of the tailings on groundwater. Wastewater is discharged from the industrial site into the Aksu riverbed after preliminary complex biological treatment at the sanitary treatment facilities. This article provides an analysis of pollutants from the processing of uranium ores. Studies have found that arsenic, molybdenum, uranium, and radium are the main pollutants that affect surface and groundwater. Under the influence of precipitation, the oxidation of ore minerals, many radioactive and chemical elements transform into more mobile forms and enter the environment. The main accumulator of radionuclides is bottom sediments. It is this component of the aquatic ecosystem that determines the mechanism and rate of redistribution of radionuclides. The analysis of water samples from the tailing dump itself and from surface water bodies in the area of the GMZ industrial site in the direction of thalwegs was carried out.