Transport and Fate of 137Cs Released From Multiple Sources in the North Atlantic and Arctic Oceans

The North Atlantic and Arctic oceans, along with the North Pacific, are the main reservoirs of anthropogenic radionuclides introduced in the past 75 years. The POSEIDON-R compartment model was applied to the North Atlantic and Arctic oceans to reconstruct 137Cs contamination in 1945–2020 due to multiple sources: global fallout, exchange flows with other oceans, point-source inputs in the ocean from reprocessing plants and other nuclear facilities, the impact of the Chernobyl accident and secondary contamination resulting from river runoff and redissolution from bottom sediments. The model simulated the marine environment as a system of 3D compartments comprising the water column, bottom sediment, and biota. The dynamic model described the transfer of 137Cs through the pelagic and benthic food chains. The simulation results were validated using the marine database MARIS. The calculated concentrations of 137Cs in the seaweed and non-piscivorous and piscivorous pelagic fish mostly followed the concentration of 137Cs in water. The concentration in coastal predator fish lagged behind the concentration in water as a result of a diet that includes both pelagic and benthic organisms. The impact of each considered source on the total concentration of 137Cs in non-piscivorous fish in the regions of interest was analyzed. Whereas the contribution from global fallout dominated in 1960–1970, in 1970–1990, the contribution of 137Cs released from reprocessing plants exceeded the contributions from other sources in almost all considered regions. Secondary contamination due to river runoff was less than 4% of ocean influx. The maximum total inventory of 137Cs in the Arctic Ocean (31,122 TBq) was reached in 1988, whereas the corresponding inventory in the bottom sediment was approximately 6% of the total. The general agreement between simulated and observed 137Cs concentrations in water and bottom sediment was confirmed by the estimates of geometric mean and geometric standard deviation, which varied from 0.89 to 1.29 and from 1.22 to 1.87, respectively. The approach used is useful to synthesize measurement and simulation data in areas with observational gaps. For this purpose, 13 representative regions in the North Atlantic and Arctic oceans were selected for monitoring by using the “etalon” method for classification.

Accumulation of legacy fallout radionuclides in cryoconite on Isfallsglaciären (Arctic Sweden) and their downstream spatial distribution

The release of legacy contaminants such as fallout radionuclides (FRNs) in response to glacier retreat is a process that has received relatively little attention to date, yet may have consequences as a source of secondary contamination as glaciers melt and down-waste in response to a warming climate. The presence of FRNs in glacier-fed catchments is poorly understood in comparison to other contaminants, yet there is now emerging evidence from multiple regions of the global cryosphere for substantially augmented FRN activities in cryoconite. Here we report concentrated FRNs in both cryoconite and proglacial sediments from the Isfallsglaciären catchment in Arctic Sweden. Activities of some FRNs in cryoconite are 2 orders of magnitude above those found elsewhere in the catchment, and above the activities found in other environmental matrices outside of nuclear exclusion zones. We also describe the presence of the short-lived cosmogenic radionuclide 7Be in cryoconite samples, highlighting the importance of meltwater–sediment interactions in radionuclide accumulation in the ice surface environment. It is currently unknown whether high accumulations of fallout radionuclides in glaciers have the potential to impact local environmental quality through down-wasting and downstream transport of contaminants to the proglacial environment through interaction with sediments and meltwater. We thus recommend that future research in this field focusses on processes of accumulation of FRNs and other environmental contaminants in cryoconite and whether these contaminants are present in quantities harmful for downstream ecosystems.

Advances in the Application of Nanocatalysts in Photocatalytic Processes for the Treatment of Food Dyes: A Review

The use of food additives (such as dyes, which improve the appearance of the products) has become more prominent, due to the rapid population growth and the increase in demand for beverages and processed foods. The dyes are usually found in effluents that are discharged into the environment without previous treatment; this promotes mass contamination and alters the aquatic environment. In recent years, advanced oxidation processes (AOPs) have proven to be effective technologies used for wastewater treatment through the destruction of the total organic content of toxic contaminants, including food dyes. Studies have shown that the introduction of catalysts in AOPs improve treatment efficiency (i.e., complete decomposition without secondary contamination). The present review offers a quick reference for researchers, regarding the treatment of wastewater containing food dyes and the different types of AOPs, with different catalyst and nanocatalyst materials obtained from traditional and green chemical syntheses.

Prioritizing Suitable Quality Assurance and Control Standards to Reduce Laboratory Airborne Microfibre Contamination in Sediment Samples

The ubiquity and distribution of microplastics, particularly microfibres, in outdoor and indoor environments makes it challenging when assessing and controlling background contamination, as atmospheric particles can be unintentionally introduced into a sample during laboratory analysis. As such, an intra-laboratory examination and literature review was completed to quantify background contamination in sediment samples, in addition to comparing reported quality assurance and control (QA/QC) protocols in 50 studies examining microplastics in sediment from 2010 to 2021. The intra-lab analysis prioritizes negative controls, placing procedural blanks in various working labs designed to prepare, process, and microscopically analyse microplastics in sediment. All four labs are subject to microfibre contamination; however, following the addition of alternative clean-air devices (microscope enclosure and HEPA air purifiers), contamination decreased by 66% in laboratory B, and 70% in laboratory C. A review of microplastic studies suggests that 82% are not including or reporting alternative clean-air devices in their QA/QC approaches. These studies are found to be at greater risk of secondary contamination, as 72% of them ranked as medium to high contamination risk. It is imperative that laboratories incorporate matrix-specific QA/QC approaches to minimize false positives and improve transparency and harmonization across studies.

Main tendencies of temporal changes for concentration of priority pollutants in sediments of the coastal areas at Vladivostok (Peter the Great Bay, Japan Sea)

Concentrations of hydrocarbons, phenols, DDT and its metabolites, Cu, Pb, Fe, Ni, DDD/DDE and DDD+DDE/DDT ratios, and total level of chemical contamination (TPF index) in the bottom sediments are traced for 16 stations in the coastal areas at Vladivostok in 1982−2017. Temporal variations of the concentrations and derived indices are classified to 4 types of dynamics, using the methods of exploratory and confirmatory factor analysis, crosscorrelation analysis, and fuzzy set classification procedure. They are: primary contamination; secondary contamination; exponential growth; and polymodal dynamics. These variations are induced by two main sources of pollution, such as the industrial influx including wastes from Vladivostok and nearby settlements, aeolian transfer and polluted precipitations, and the terrigenous influx with polluted freshwater discharge. Impact of the first source prevails in the Golden Horn Bay, Diomid Inlet and Eastern Bosphorus Strait, and the second source is important for the Amur and Ussuri Bays (the coast of Vladivostok in these bays is influenced by both sources with predominance of the second). The terrigenous impact has two modes depended on certain processes of contamination: the permanent pollution inherent in the types of secondary contamination and exponential growth and the extreme pollution that forms the polymodal dynamics. The secondary contamination follows the primary one with a lag of 6–7 years. The secondary contamination of terrigenous usually has inverse correlation with the Razdolnaya/Suifen River discharge; for instance, strengthening of the freshwater inflow causes lower concentrations of Cu and Pb in the bottom sediments due to dilution effect. On the contrary, contamination depends directly on the Razdolnaya/Suifen River discharge for the exponential growth of terrigenous — the stronger the freshwater inflow, the higher the concentrations of Fe, Ni, and phenols (the latter is a sign of eutrophication). The types of dynamics change following the balance between pollution and self-cleaning of the sediments that is determined by external factors, as a drop in economic activity and its subsequent recovery, limitation and finally ban for using of tetraethyl lead additive, extreme floods on rivers, etc.

Hyper-accumulation of legacy fallout radionuclides in cryoconite on Isfallsglaciären (Arctic Sweden) and their downstream distribution

The release of legacy fallout radionuclides (FRNs) in response to glacier retreat is a process that has received relatively little attention to date, yet may have important consequences as a source of secondary contamination as glaciers melt and down-waste in response to a warming climate. The prevalence of FRNs in glacier-fed catchments is poorly understood in comparison to other contaminants, yet there is now emerging evidence from multiple regions of the global cryosphere for substantially augmented FRN activities in cryoconite. Here we report concentrated FRNs in both cryoconite and proglacial sediments from the Isfallsglaciären catchment in Arctic Sweden. Activities of some FRNs in cryoconite are two orders of magnitude above those found elsewhere in the catchment, and above the activities found in other environmental matrices outside of nuclear exclusion zones. We also describe the presence of the short-lived cosmogenic radionuclide 7Be in cryoconite samples, highlighting the importance of meltwater-sediment interactions in radionuclide accumulation in the ice surface environment. The presence of fallout radionuclides in glaciers may have the potential to impact local environmental quality through both isolated hotspots of radioactivity caused by glacier down-wasting, and downstream transport of contaminants to the proglacial environment through interaction with sediments and meltwater. We thus recommend that future research in this field focusses on processes of accumulation of FRNs and other environmental contaminants in cryoconite, and whether these contaminants are present in quantities harmful for both local and downstream ecosystems.

FEATURES OF TECHNOGENIC RADIONUCLIDES IN PRIVATE SECTOR OF SEMEY TOWN

This article considers the issues of contamination with man-made radionuclides in the land of the city of Semipalatinsk. The purpose of accounting for the impact of land contamination with radionuclides is the assessment of the degree of impact of secondary contamination of urban areas and the definition of the boundary of this contamination, affecting the cadastral value. Factors contributing to the spread of pollution, such as in a coal warehouse, as well as in the burning of coal, during delivery, on automobile roads, which delivers coal to industrial enterprises, boiler-houses and the consumer sector. The sources of secondary pollution, which are located in the city, are considered. It has been established that the cadastral value will have an impact on the level of contamination of the land plot with man-made radionuclides. It is proposed to supplement the boundary plan of contaminated land plots.

Controlled Cracking of Large Size Concrete Structures by a Steam Pressure Cracking Agent

The dismantling of large concrete structures causes environmental pollution due to the dispersion of polluted micro-particles. The purpose of this study is to develop an environmentally friendly demolition method. Steam pressure cracking (SPC) is a method that can safely and quickly separate concrete because there is less vibration compared to the explosion method. To date, the authors have shown that the direction of cracking in a small sample can be controlled by an induction hole. The principle of control is that the elastic wave of compression stress generated from the SPC reaction changes to a tensile elastic wave at the induction hole, and a crack is initiated. In this study, it was shown that the direction of crack propagation can be controlled by using induction holes in large concrete structures that are 1m on each side. Further, in the SPC method, the large amount of concrete powder generated by the explosion method is not produced, and there is no risk of secondary contamination by fine concrete powder. It was also possible to separate small pieces from the end face of the large concrete by SPC and induction holes. The area over which the crack propagated depends on the energy generated from the SPC agent, and the relationship was linear. By applying an SPC agent to dismantling large concrete structures, we can achieve controlled cracking safely and quickly without any environmental pollution.

Comparison of the disinfecting effect of sodium hypochlorite aqueous solution and surfactant on hospital kitchen hygiene using adenosine triphosphate swab testing

The Japanese Ministry of Health requires large-scale cooking facilities to use sodium hypochlorite aqueous solution (HYP) on food preparation tools, equipment, and facilities to prevent secondary contamination. This study aimed to compare the disinfecting effect of HYP and surfactant using adenosine triphosphate (ATP) swab testing on large-scale equipment and facilities that could not be disassembled and disinfected in hospital kitchen. From May 2018 to July 2018, ATP swab tests were performed on the following six locations in the Shizuoka Cancer Centre Dietary Department Kitchen: cooking counter, mobile cooking counter, refrigerator handle, conveyor belt, tap handle, and sink. Six relative light unit (RLU) measurements were taken from each location. The log10 values of the RLU measurements were evaluated by dividing the samples into two groups: the control group (surfactant followed by HYP swabbing) and the HYP group (HYP swabbing only). The results showed that the RLUs (log10 values) in both the groups improved after disinfection (p<0.05), except for the RLUs (log10 values) of the mobile cooking counter, tap handle, and sink in the control group after the HYP swab. The changes in the RLU (log10 value) did not differ between the two groups for all locations of the kitchen. Hence, HYP swabbing of large-scale equipment and facilities provides the same level of disinfection as surfactants and can be as beneficial.