Search

Cryoconite, granule-shaped debris found on the surface of glaciers, is known for trapping substantial quantities of pollutants such as radioactive nuclides and heavy metals. This study investigates contamination levels, sources and spatial variability of natural and artificial radioisotopes in cryoconite from Mittivakkat Gletsjer in southeast Greenland by determining the activity and atomic ratios of selected radionuclides. The maximum activity concentrations of artificial radioisotopes were 1129 ± 34 Bq kg−1 for 137Cs, 3.75 ± 0.39 Bq kg−1 for 238Pu; 62.6 ± 6.1 Bq kg−1 for 239+240Pu, and 23.2 ± 2.4 Bq kg−1 for 241Am. For natural radionuclides, the maximum concentrations were 4900 ± 120 Bq kg−1 for 210Pb, 470 ± 17 Bq kg−1 for 40K, and 42.9 ± 1.7 Bq kg−1 for 228Ra. Statistically significant and positive correlations were found between altitude and activity concentrations of 137Cs, 238,239+240Pu, 241Am, and 210Pb. This linkage could be explained by lower ablation rates with altitude and higher presence of supraglacial channels near the glacier front. The major source of plutonium shown by 238Pu/239+240Pu activity ratios in the surveyed area can be attributed to global fallout and is consistent with the activity ratios of 241Am/239+240Pu. The 239+240Pu/137Cs activity ratio suggests that the main source of cesium is global fallout, but possible input from Chernobyl cannot be excluded. Lower values of 240Pu/239Pu atomic ratio indicate a mixture of possible sources, including fallout derived from low-yield nuclear detonations such as from the Novaya Zemlya Test Site or Semipalatinsk. Overall, the findings of this study show that the radionuclide contamination levels on glaciers in southeast Greenland are relatively normal compared to other glaciers worldwide and that the dominating source is global fallout. [Display omitted] • Spatial distribution of artificial radioisotopes is related to ablation rates and presence of supraglacial channels. • Activity concentrations of 40K in cryoconite are lower than average for continental crust. • Global fallout is a main source of plutonium and cesium in the surveyed area. • Low energy detonations (e.g. Novaya Zemlya or Semipalatinsk) might have influenced the 240Pu/239Pu ratio in cryoconite. [ABSTRACT FROM AUTHOR]

Nuclear waste management is a crucial aspect as the most significant threat to the ecosystem is caused by radioactive waste in which thorium contamination remains a prominent issue. This work represents an integrated approach for the elimination of thorium through the adsorption technique and subsequent electrochemical sensing using Magnetite@Graphene Oxide@Chitosan (M@GO@Cs). Moreover, the sorption of Th(IV) ions is optimized through batch studies, which are consistent with the results derived from ANOVA using the Box-Behnken Design model, and the ideal parameters resulted in 95.79% removal efficiency of Th(IV) ions using 6 mg of adsorbent in 10 mL of 50 mg/L Th(IV) ions solution at a pH of 5 within 20 min. Maximum adsorption capacity (833.33 mg/g) is obtained from Langmuir adsorption isotherm and process was aligned with the pseudo-second-order kinetic model. M@GO@Cs exhibited high recyclability sustaining high performance across nine consecutive adsorption-desorption cycles while maintaining excellent removal efficiency up to 85%. Furthermore, the electrochemical characterization of the synthesized M@GO@Cs nanoadsorbent was studied using the Cyclic Voltammetry, and Electron Impedance Spectroscopy techniques and quantification of Th(IV) ions was done utilizing the Differential Pulse Voltammetry method with the Limit of Detection (LOD) of 0.2 mg/L within a linear range of 10–100 mg/L. [Display omitted] • Engineering magnetite-based nanocomposite referred to as M@GO@Cs. • The synthesized nanocomposite is employed for selective adsorption of Th(IV) ions. • Box-Behnken Design model is used for the optimization of the adsorption parameters. • Quantification of Th(IV) ions using Electrochemical sensing approach. [ABSTRACT FROM AUTHOR]

The release of radionuclides, including Cesium-137 (137Cs), Strontium-90 (90Sr), Uranium-238 (238U), Plutonium-239 (239Pu), Iodine-131 (131I), etc., from nuclear contamination presents profound threats to both the environment and human health. Traditional remediation methods, reliant on physical and chemical interventions, often prove economically burdensome and logistically unfeasible for large-scale restoration efforts. In response to these challenges, bioremediation has emerged as a remarkably efficient, environmentally sustainable, and cost-effective solution. This innovative approach harnesses the power of microorganisms, plants, and biological agents to transmute radioactive materials into less hazardous forms. For instance, consider the remarkable capability demonstrated by Fontinalis antipyretica , a water moss, which can accumulate uranium at levels as high as 4979 mg/kg, significantly exceeding concentrations found in the surrounding water. This review takes an extensive dive into the world of bioremediation for nuclear contaminant removal, exploring sources of radionuclides, the ingenious resistance mechanisms employed by plants against these harmful elements, and the fascinating dynamics of biological adsorption efficiency. It also addresses limitations and challenges, emphasizing the need for further research and implementation to expedite restoration and mitigate nuclear pollution's adverse effects. [Display omitted] • Discussed the release of radionuclides which poses risks to environment & health. • Elaboration on bioremediation which is efficient, eco-friendly, and cost-effective. • Utilizes natural abilities of microorganisms and plants. • Discussed challenges include site complexity and long-term impacts. [ABSTRACT FROM AUTHOR]

Uranium is a naturally existing radioactive element present in the Earth's crust. It exhibits lithophilic characteristics, indicating its tendency to be located near the surface of the Earth and tightly bound to oxygen. It is ecotoxic, hence the need for its removal from the aqueous environment. This paper focuses on the variety of water treatment processes for the removal of uranium from water and this includes physical (membrane separation, adsorption and electrocoagulation), chemical (ion exchange, photocatalysis and persulfate reduction), and biological (bio-reduction and biosorption) approaches. It was observed that membrane filtration and ion exchange are the most popular and promising processes for this application. Membrane processes have high throughput but with the challenge of high power requirements and fouling. Besides high pH sensitivity, ion exchange does not have any major challenges related to its application. Several other unique observations were derived from this review. Chitosan/ Chlorella pyrenoidosa composite adsorbent bearing phosphate ligand, hydroxyapatite aerogel and MXene/graphene oxide composite has shown super-adsorbent performance (>1000 mg/g uptake capacity) for uranium. Ultrafiltration (UF) membranes, reverse osmosis (RO) membranes and electrocoagulation have been observed not to go below 97% uranium removal/conversion efficiency for most cases reported in the literature. Heat persulfate reduction has been explored quite recently and shown to achieve as high as 86% uranium reduction efficiency. We anticipate that future studies would explore hybrid processes (which are any combinations of multiple conventional techniques) to solve various aspects of the process design and performance challenges. [Display omitted] • U(VI) removal from water via various techniques was reviewed and compared. • Membrane filtration and ion exchange are the most promising processes for this application. • Membrane processes have high throughput but high power requirements and fouling. • Ion exchange lacks any major challenges besides pH sensitivity. • Hybrid processes could overcome process design and performance challenges. [ABSTRACT FROM AUTHOR]

Abstract This study investigates multi-element composition of soil, mosses and mushrooms from a pristine temperate rainforest (Prašnik, Croatia). Additionally, the activity levels of natural (238U, 235U and 232Th decay chains, 40K and 7Be) and anthropogenic (137Cs and 134Cs) radionuclides in the investigated soil samples, obtained by gamma spectrometry, provide baseline of environmental radioactivity levels in this area. The aim of investigation was to explore the uptake of metal(loid)s by bioindicator species (mosses, mushrooms) growing in a pristine environment characterized by naturally elevated concentration of metals. The calculated enrichment and bioaccumulation factors, correlations between different groups of elements and similar multi-element patterns in mosses, mushrooms and soil samples revealed the prevailing influence of the local substrate geochemistry on element concentrations in mosses and mushrooms. The results suggest atmospheric deposition of Bi, Cd and Pb, while radionuclide activities point to atmospheric fall-out (including global contamination by radiocaesium) and influence of the pedological substrate. The confined area of investigation, with limited variations in soil characteristics and geological composition, allowed clearer insight into the origin of metal(loid)s in mosses and mushrooms. On the other hand, using bioindicator species with different element uptake mechanisms enabled distinction between different sources of elements. Graphical abstract Image 1 Highlights • Multi-element composition of soil, mosses and mushrooms from a pristine forest. • Soil radioactivity levels (238U, 235U, 232Th, 40K, 7Be,137Cs, 134Cs) determined. • Element levels in mosses and mushrooms influenced by substrate geochemistry. • Indications of atmospheric deposition of Bi, Cd and Pb. [ABSTRACT FROM AUTHOR]

Heavy metals and radionuclides in water are a global environmental issue, which has been receiving considerable attention worldwide. Water-stable MOFs are green and recyclable materials to eliminate the environmental impacts caused by the hazardous heavy metal ions and radionuclides in water. This paper presents a systematical review on the current status of water-stable MOFs that capture and convert a wide range of heavy metal ions (e.g., As(III)/As(V), Pb(II), Hg(II), Cd(II), and Cr(III)/Cr(VI)) and radionuclides (e.g., U(VI), Se(IV)/Se(VI) and Cs(I)) in aqueous solution. Water-stable MOFs and MOF-based composites exhibit the superior adsorption capability for these metal species in water. Significantly, MOFs show high selectivity in capturing target metal ions even in the presence of multiple water constituents. Mechanisms involved in capturing metal ions are described. MOFs also have excellent catalytic performance (photocatalysis and catalytic reduction by formic acid) for Cr(VI) conversion to Cr(III). Future research is suggested to provide insightful guidance to enhance the performance of the MOFs in capturing target pollutants in aquatic environment. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive statistical analysis of the cosmogenic radioisotope 7 Be measured in surface air in ten stations over Spain for a 9 years period (from January 2006 to December 2014). Besides the analysis of 7 Be seasonal and inter-annual variability, 7 Be frequency distributions and its correlations with meteorological variables observed in the 10 sampling sites were investigated. The second part of this paper focuses on a feasibility study for the application of the Artificial Neural Networks (ANNs) to predict monthly 7 Be activity concentrations using meteorological variables, PM10 concentrations and the sunspot number as input parameters. Notwithstanding the low correlations found between 7 Be and input parameter, the performance of the ANNs, as evaluated by the relevant statistical parameters, demonstrates their capability to correctly predict 7 Be monthly activities in the 10 Spanish sampling sites. [ABSTRACT FROM AUTHOR]

This article studies sorption regularities and estimates the strength of 137Cs fixation by various soil horizons in peaty-podzolic-gleyic soils under a model experiment. The interaction time varied from 1 week to 3 months while Cs concentration varied from trace to micromolar concentrations. To understand the interaction mechanisms of cesium with individual soil components, we used the method of sequential removal of organic matter and non-silicate iron compounds from the soil before the sorption experiment. Illite and vermiculite were found to be the main soil components for radiocesium sorption in the mineral soil horizons. The highly selective positions (FES – frayed edge sites) of the abovementioned minerals fixed radiocesium so strongly that even strong acid solutions could not extract it from soil. Organic matter significantly contributed to the fixation of radiocesium in the soil only in the ELih horizon which contained 4.71% C org. In the ELg horizon, a small amount of organic matter was able to inhibit sorption by blocking highly selective to radiocesium FES. The Tessier sequential extraction method of radiocesium revealed that all the studied soil samples could strongly fix the radionuclide. Increasing the interaction period up to three months under periodic wetting and drying contributed to the increased proportion of strongly bound 137Cs. The results of sorption experiments carried out before and after the removal of non-silicate iron compounds from the soil indicate that 137Cs has little or no sorption on the surface of iron hydroxides. [Display omitted] • The patterns of interaction of cesium with peaty-podzolic-gleyic soil was established. • In the upper horizon, soil organic matter takes part in Cs sorption. • In the underlying soil horizons, SOM block the most Cs-selective FES. • The main mineral soil components for Cs sorption are illites and vermiculites. [ABSTRACT FROM AUTHOR]

Following the Fukushima Dai-ichi Nuclear Power Station accident, regional road dust, heavily contaminated with radiocesium, now represents a potential source of radiocesium pollution in river water. To promote effective countermeasures for reducing the risk from radiocesium pollution, it is important to understand its sources. This study evaluated the utility of metals, including Al, Fe, and Zn as road dust tracers, and applied them to analyze sources of 137 Cs in rivers around Fukushima during wet weather. Concentrations of Zn in road dust were higher than agricultural and forest soils, whereas concentrations of Fe and Al were the opposite. Concentrations of Zn were weakly but significantly correlated with benzothiazole, a molecular marker of tires, indicating Zn represents an effective tracer of road dust. Al, Fe, and Zn were frequently detected in suspended solids in river water during wet weather. Distribution coefficients of these metals and 137 Cs exceeded 10 4 , suggesting sorptive behavior in water. Although concentrations of Al, Fe, Zn, and 137 Cs were higher in fine fractions of road dust and soils than in coarse fractions, use of ratios of 137 Cs to Al, Fe, or Zn showed smaller differences among size fractions. The results demonstrate that combinations of these metals and 137 Cs are useful for analyzing sources of radiocesium in water. These ratios in river water during wet weather were found to be comparable with or lower than during dry weather and were closer to soils than road dust, suggesting a limited contribution from road dust to radiocesium pollution in river water. [ABSTRACT FROM AUTHOR]

Organic sediments in aquatic ecosystems are well known sinks for nutrients, silicon, and metal(loid)s. Organic matter-consuming organisms like invertebrate shredders, grazers, and bioturbators significantly affect element fixation or remobilization by changing redox conditions or binding properties of organic sediments. Little is known about the effect of filter feeders, like the zebra mussel Dreissena polymorpha , an invasive organism in North American and European freshwater ecosystems. A laboratory batch experiment exposing D . polymorpha (∼1200 organisms per m 2 ) to organic sediment from a site contaminated with arsenic, copper, lead, and uranium revealed a significant uptake and accumulation of arsenic, copper, iron, and especially uranium both into the soft body tissues and the seashell. This is in line with previous observations of metal(loid) accumulation from biomonitoring studies. Regarding its environmental impact, D . polymorpha significantly contributed to mobilization of silicon, iron, phosphorus, arsenic, and copper and to immobilization of uranium ( p < 0.001), probably driven by redox conditions, microbial activity within the gut system, or active control of element homeostasis. No net mobilization or immobilization was observed for zinc and lead, because of their low mobility at the prevailing pH of 7.5–8.5. The present results suggest that D . polymorpha can both ameliorate (nutrient mobilization, immobilization of toxicants mobile under oxic conditions) or aggravate negative effects (mobilization of toxicants mobile under reducing conditions) in ecosystems. Relating the results of the present study to observed population densities in natural freshwater ecosystems suggests a significant influence of D . polymorpha on element cycling and needs to be considered in future studies. [ABSTRACT FROM AUTHOR]

Procedures for removing harmful radiation from interior and exterior surfaces of homes and businesses after a nuclear or radiological disaster may generate large volumes of radiologically contaminated waste water. Rather than releasing this waste water to potentially contaminate surrounding areas, it is preferable to treat it onsite. Retention barrels are a viable option because of their simplicity in preparation and availability of possible sorbent materials. This study investigated the use of aluminosilicate clay minerals as sorbent materials to retain 137 Cs, 85 Sr, and 152 Eu. Vermiculite strongly retained 137 Cs, though other radionuclides displayed diminished affinity for the surface. Montmorillonite exhibited increased affinity to sorb 85 Sr and 152 Eu in the presence of higher concentrations of 137 Cs. To simulate flow within retention barrels, vermiculite was mixed with sand and used in small-scale column experiments. The GoldSim contaminate fate module was used to model breakthrough and assess the feasibility of using clay minerals as sorbent materials in retention barrels. The modeled radionuclide breakthrough profiles suggest that vermiculite-sand and montmorillonite-sand filled barrels could be used for treatment of contaminated water generated from field operations. [ABSTRACT FROM AUTHOR]

Surface of glaciers is covered by mineral and organic dust, together with microorganisms forming cryoconite granules. Despite fact that glaciers and ice sheets constitute significance part of land surface, reservoir of freshwater, and sites of high biological production, the knowledge on the cryoconite granules still remain unsatisfactory. This study presents information on radionuclide and heavy metal contents in cryoconites. Cryoconites collected from the Hans Glacier in SW Spitsbergen reveal high activity concentrations of anthropogenic ( 238,239,240 Pu, 137 Cs, 90 Sr) and natural ( 210 Pb) radionuclides. The 238 Pu/ 239+240 Pu activity ratios in these cryoconites significantly exceed the mean global fallout ratio (0.025). The 238 Pu/ 239+240 Pu ranged from 0.064 to 0.118. The 239+240 Pu/ 137 Cs varied from 0.011 ± 0.003 to 0.030 ± 0.007. Such activity ratios as observed in these cryoconites were significantly higher than the values characterizing global fallout, pointing to possible contributions of these radionuclides from other sources. Heavy metals (Pb, Cd, Cu, Zn, Fe, and Mn) in cryoconites exceed both UCC concentrations and local rocks’ concentrations, particularly for cadmium. The concentration ratios of stable lead isotopes ( 206 Pb/ 207 Pb, 208 Pb/ 206 Pb) were determined to discriminate between the natural and anthropogenic sources of Pb in cryoconites and to confirm the strong anthropogenic contribution to heavy metal deposition in the Arctic. In investigated cryoconite holes, two groups of invertebrates, both extremophiles, Tardigrada and Rotifera were detected. Our study indicate that cryoconites are aggregates of mineral and organic substances on surfaces of glaciers are able to accumulate large amounts of airborne pollutants bound to extracellular polymeric substances secreted by microorganisms. [ABSTRACT FROM AUTHOR]

The concentrations of radionuclides, polycyclic aromatic hydrocarbons (PAHs) and heavy metals were measured in soil samples collected from school backyards and playgrounds in Kragujevac, one of the largest cities of Central Serbia. The activity concentrations of 226 Ra, 232 Th, 40 K and 137 Cs were determined using the HPGe semiconductor detector. The average values were 34.6, 44.7, 428.9 and 45.1 Bq kg −1 , respectively. The correlation between the activity concentrations of 226 Ra in the soil samples and the results of the previous measurement of 222 Rn concentrations in the indoor air was examined. The absorbed dose rates, the annual effective doses and excess lifetime cancer risk were also estimated. The activity concentrations of 226 Ra and 232 Th have shown normal distribution. The collected soil samples were analysed for PAHs by HPLC. All analysed soil samples contained PAHs, and their total amounts (for 15 measured compounds) were found to be between 0.038 and 3.136 mg kg −1 of absolutely dry soil (a.d.s). In addition the concentrations of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn were measured in the fourteen soil samples collected from the playgrounds of kindergartens. [ABSTRACT FROM AUTHOR]

Water consumption has grown in recent years due to rising urbanization and industry. As a result, global water stocks are steadily depleting. As a result, it is critical to seek strategies for removing harmful elements from wastewater once it has been cleaned. In recent years, many studies have been conducted to develop new materials and innovative pathways for water purification and environmental remediation. Due to low energy consumption, low operating cost, and integrated facilities, membrane separation has gained significant attention as a potential technique for water treatment. In these directions, MXene which is the advanced 2D material has been explored and many applications were reported. However, research on MXene-based membranes is still in its early stages and reported applications are scatter. This review provides a broad overview of MXenes and their perspectives, including their synthesis, surface chemistry, interlayer tuning, membrane construction, and uses for water purification. Application of MXene based membrane for extracting pollutants such as heavy metals, organic contaminants, and radionuclides from the aqueous water bodies were briefly discussed. Furthermore, the performance of MXene-based separation membranes is compared to that of other nano-based membranes, and outcomes are very promising. In order to shed more light on the advancement of MXene-based membranes and their operational separation applications, significant advances in the fabrication of MXene-based membranes is also encapsulated. Finally, future prospects of MXene-based materials for diverse applications were discussed. [Display omitted] • Structure of MXene is briefly presented. • A comprehensive elaboration of synthesis of MXene and preparation of MXene-based membrane. • Properties of MXene and effect of properties on the performance of MXene, along with a comparison with other nanomembranes. • Removal of organic pollutants, heavy metals, and radionuclides from water by MXene. • Current challenges and future scope of MXene in the purification of water. [ABSTRACT FROM AUTHOR]

Abstract: The release of radioactive materials from the Fukushima nuclear power plant after the Great East Japan Earthquake on 11 March 2011 poses health risks. In this study, the intake of iodine 131 (I-131) in drinking water and foods (milk, dairy products, and vegetables) by citizens of Tokyo was estimated. The effects of countermeasures (restrictions on the distribution of foods and the distribution of bottled water for infants) on reducing intake were also evaluated. The average thyroid equivalent doses without countermeasures from 21 March 2011 were 0.42mSv in adults, 1.49mSv in children, and 2.08mSv in infants. Those with countermeasures were 0.28, 0.97, and 1.14mSv respectively, reductions of 33%, 35%, and 45%. Drinking water contributed more to intake by adults and children than foods. The intake of I-131 within the first 2weeks was more than 80% of the estimated intake, owing to its short half-life, indicating that rapid countermeasures are important in reducing intake. The average risks of cancer incidence and mortality due to I-131 for infants were estimated to be 3×10−5 and 0.2×10−5, respectively, lower than the annual risks of traffic accidents, naturally occurring radioactive material (potassium 40), and environmental pollutants such as diesel exhaust particles. [Copyright &y& Elsevier]

Abstract: Earthworms were exposed for 56d to a contaminated soil, from an abandoned uranium mine, and to the natural reference soil LUFA 2.2. Histological changes in earthworm’s body wall (epidermis, circular and longitudinal muscles) and gastrointestinal tract (chloragogenous tissue and intestinal epithelium) were assessed, after 0, 14 and 56d of exposure. Results have shown alterations in all the studied tissues after 14d of exposure (except for the intestinal epithelium), yet more severe effects were registered after 56d of exposure. Herein we report histopathological alterations as a good biomarker for the evaluation of soil quality. We also demonstrate that morphological changes in the body wall and gastrointestinal tract, are important endpoints that could be added to earthworm’s standardized tests, for the evaluation of soil toxicity, as part of the risk assessment of contaminated areas. [Copyright &y& Elsevier]

Contamination of water sources with various organic and inorganic non-biodegradable pollutants is becoming a growing concern due to industrialization, urbanization, and the inefficiency of traditional wastewater treatment processes. Transition Metal Carbides/Nitrides (MXenes) are emerging as advanced nanomaterials of choice for treating contaminated water owing to their excellent conductivity, mechanical flexibility, high specific surface area, scalable production, rich surface functionalities, and layered morphology. MXenes have demonstrated enhanced ability to adsorb various organic and inorganic contaminants depending upon their surface terminal groups (-OH, –F, and –O) and interlayer spacing. Titanium carbide (Ti 3 C 2 T x) is most researched to date due to its ease of processing and stability. Ti 3 C 2 T x has shown excellent performance in absorbing heavy metal ions and radioactive heavy metals. This review summarizes state-of-the-art Ti 3 C 2 T x synthesis, including selective etching techniques, optimization of the desired adsorption features (controlling surface functional groups, intercalation, sonication, and functionalization), and regeneration and adsorption mechanism to remove contaminants. Furthermore, the review also compares the adsorption performance of Ti 3 C 2 T x with other commercial adsorbents (including chitosan, cellulose, biomass, and zeolites). Ti 3 C 2 T x has been found to have an adsorption efficiency of more than 90% in most studies due to its layered structure, which makes the functional groups easily accessible, unique and novel compared to other conventional nanomaterials and adsorbents. The challenges, potential solutions, and prospects associated with the commercial development of Ti 3 C 2 T x as adsorbents are also discussed. The review establishes a framework for future wastewater treatment research using MXenes to address the global problem of water scarcity. [Display omitted] • Strategies and optimization techniques to control Ti 3 C 2 T x properties are summarized. • Ti 3 C 2 T x performance for heavy metal ion and radionuclide recovery is discussed. • Mechanism leading to excellent adsorption performance of Ti 3 C 2 T x is presented. • Ti 3 C 2 T x absorption performance comparison with commercial adsorbents is presented. • Bottlenecks, possible solutions, and industrial prospects of Ti 3 C 2 T x as adsorbent are discussed. [ABSTRACT FROM AUTHOR]

Exposure to radionuclides, especially in food, can endanger the health of consumers. In this study, a systematic review and meta-analysis were performed regarding the concentration of radionuclides in tuna fish muscle. International databases including PubMed, Scopus, and Embase were searched to find articles regarding the concentration of radionuclides in tuna fish muscle from 1 January 2000 to 20 February 2021. The lowest and highest concentration of radionuclides was related to Caesium-137 (137Cs) and Potassium-40 (4 K), respectively. The rank order of radionuclides based on their pooled concentration was 4 K (370.157 Bq/kg) > 210Po Polonium-210 (26.312 Bq/kg) > 210Pb (5.339 Bq/kg) > 226Ra (4.005 Bq/kg) > 137Cs (0.415 Bq/kg). The health risk assessment based on annual effective dose indicates that consumers are at the safe range of health risk (H < 1 mSv/y). The continuous monitoring concentration of radionuclides in seafood and health risk assessment should be recommended. [Display omitted] • The rank order of radionuclides based on their pooled concentration was 4 K > 210Po > 210Pb > 226Ra >137Cs. • Annual effective dose indicates is lower than 1 mSv/y. • Consumers are at the safe range of health risk. [ABSTRACT FROM AUTHOR]

The adsorptive removal performance of strontium (Sr) through bio-mineralization metabolism under various parameters was evaluated in this study. The primary mechanism of bio-mineralization used in this study was the urea hydrolysis process through bacterial enzymatic catalysis. Bacillus sp, which was isolated from river sediment, was used as a ureolytic bacteria. Various environmental conditions were set as different initial concentrations of Sr (10, 50, 100, 200, and 500 mg/L), and various ratios of Mg/Ca (4, 2, 1, 0.5, and 0.25). The concentrations of Sr2+, Ca2+, and Mg2+ in the solution of the batch experiment were measured to identify the bio-mineralization performance and the removal rate of Sr. In addition, the main Sr removal mechanism of ureolytic bacteria was identified. As a result, for Sr removal of bacteria, the bio-mineralization mechanism was more predominant than the adsorption of Sr. The rapid growth and high nucleation site production were observed when the initial concentration of Sr2+ increased and the Mg/Ca ratio was lowered, resulting in high biomineralization performance and Sr removal rate. The main phases of carbonate minerals formed in the presence of Sr, Ca, and Mg were SrCO 3 and SrCa(CO 3) 2. Mg2+ could retard the bacterial growth and participate in the formation of carbonate minerals, when a large amount of Mg2+ was present. Furthermore, the desorption rate of Sr2+ from bacterial pastes containing the carbonate minerals increased as the concentration of HCl increased, although the carbonate minerals were in a stable state. [Display omitted] • The cell surface area of bacteria can be a decisive factor for removal rate of Sr. • The Sr adsorptive removal rate can be influenced by various environmental factors. • For the Sr removal process, bio-mineralization is more predominant than adsorption. • Mg2+ only participate in carbonate mineral formation when present in large amounts. • The co-existing cations can change the interaction between bacterial cell surfaces. [ABSTRACT FROM AUTHOR]

Breast milk monitoring studies of persistent and toxic environmental contaminants are of primary importance for carrying out an adequate risk assessment at the actual levels of human exposure and represent a major source of information on infant perinatal exposure. Milk specimens from mothers of the general population of the Venice and Rome areas were collected over the 1998–2001 period, pooled, and analyzed for selected persistent organic pollutants such as polychlorodibenzodioxins (PCDDs), polychlorodibenzofurans (PCDFs), polychlorobiphenyls (PCBs), organochlorinated pesticides (p,p′-DDE, p,p′-DDT, hexachlorobenzene), and polybromodiphenyl ethers (PBDEs), and the heavy metals Cd, Co, Cu, Hg, Mn, Pb, Sn, and Zn. The goal was to verify whether mother milk from the Venice area, whose lagoon is partly under direct industrial impact, had a contaminant load greater than that from the Rome area, primarily urban. For mothers from the Venice area, the correlation between fish and fishery product consumption and contaminant concentrations in milk was also explored, with however inconclusive results. The concentrations of PCDDs, PCDFs, dioxin-like PCBs, and organochlorinated pesticides determined in this study were compared with those available from a previous analytical work carried out on 1987 human milk pools of domestic origin: the declining trend of the aforesaid contaminants in milk is confirmed to be in agreement with what was observed in other European countries. The breast milk content of 137Cs and 40K radionuclides was also determined and compared with data obtained in other research programmes carried out in Italy: the health risk for breastfed infants was deemed to be not significant. [Copyright &y& Elsevier]

Abstract: The objective of the study was to provide global probability density functions (PDFs) representing the uncertainty of distribution coefficients (Kds) in freshwater for radioisotopes of Co, Cs, Sr and I. A comprehensive database containing Kd values referenced in 61 articles was first built and quality scores were affected to each data point according to various criteria (e.g. presentation of data, contact times, pH, solid-to-liquid ratio, expert judgement). A weighted bootstrapping procedure was then set up in order to build PDFs, in such a way that more importance is given to the most relevant data points (i.e. those corresponding to typical natural environments). However, it was also assessed that the relevance and the robustness of the PDFs determined by our procedure depended on the number of Kd values in the database. Owing to the large database, conditional PDFs were also proposed, for site studies where some parametric information is known (e.g. pH, contact time between radionuclides and particles, solid-to-liquid ratio). Such conditional PDFs reduce the uncertainty on the Kd values. These global and conditional PDFs are useful for end-users of dose models because the uncertainty and sensitivity of Kd values are taking into account. [Copyright &y& Elsevier]

Abstract: The influence of two types of colloids (natural organic matter, NOM), a colloid with high affinity for radionuclides (RN(s)), and hydrophilic synthetic latex (SHL), a colloid with low affinity for RN(s) on the transfer of 60Co and 85Sr in a silica sand column was studied under different physicochemical conditions : pH (4.9), ionic strength (10−3 M and 10−2 M), concentration of colloids (100mgl−1, 10mgl−1), flow velocity (12.4cmh−1 and 3.7cmh−1), water saturation of the column (100% and 70%). In the absence of colloids, the transfer of 60Co and 85Sr was retarded compared to the transfer of the conservative tracer. In the presence of colloids and according to the specific physicochemical conditions, an acceleration or retardation of 60Co and 85Sr transfer was observed compared to their transfer in the absence of colloids. Our results evidenced that any colloids even with low reactivity could significantly modify the RN transfer. However, the extent to which the transfer was influenced differs according to the colloid type; the NOM exhibiting higher impact than SHL. Batch experiments helped in interpreting of the interactions between the colloids, RN(s) and solid phase observed in column. [Copyright &y& Elsevier]

An empirical method was applied to estimate the 222Rn fluxes distribution across the Campania region (Italy) by using both gamma-rays and U, Th, K concentrations in soils. As a first step, K, Th and U soil concentrations and 4 K, 238U and 232Th activity have been converted into their own specific activity to calculate the Terrestrial Gamma Dose Rate (TGDR). This latter has been then used to determine the 222Rn fluxes across the region. Regardless of the radiometric or geochemical origin, 222Rn fluxes reached, as expected, their maximum values in correspondence with the volcanic centres of Campania (Mt. Somma-Vesuvius, Phlegrean Fields, Mt. Roccamonfina). However, comparing the results obtained from the two different datasets, it was also possible to infer the existence of contributions to surficial 222Rn fluxes proceeding from both some underlying geological bodies and active seismogenic sources. In line with some national regulations, the 222Rn flux esteemed from gamma radiations was also used to assess the possible regional distribution of risk deriving from the indoor environmental exposure to 222Rn; results were compared with standardized incidence rates (SIRs) of lung cancer for an area on the south-western sector of Mt. Somma-Vesuvius showing a potential spatial relationship among flux data and SIRs. [Display omitted] • Elemental concentrations and activity values of radionuclides were used to calculate the terrestrial gamma dose rate (TGDR). • 222Rn fluxes released from the ground were estimated using terrestrial gamma dose rate for Campania region (Italy). • Spatial patterns of 222Rn fluxes show connections with regional geolithological variability and some seismogenic sources. • 222Rn fluxes from radiometric data were used to assess the risk. [ABSTRACT FROM AUTHOR]

MXene, comprised of two-dimensional transition metal carbides/nitride, has emerged as a novel material suitable for environmental remediation of toxic compounds. Due to their inherent and superior physical and chemical properties, MXene is employed in separation techniques like photocatalysis, adsorption, and membrane separation. MXene is equipped with a highly hydrophilic surface, ion exchange property, and robust surface functional groups. In this review paper, a comprehensive discussion on the structural patterns, preparation, properties of MXene and its application for the removal of toxic pollutants like Radionuclide, Uranium, Thorium, and dyes is presented. The mechanism of removal of the pollutants by MXene is extensively reviewed. Synthesis of MXene based membranes, their properties, and application for water purification and properties were also discussed. This review will be highly helpful to understand critically the methods of synthesis and use of MXene material for priority environmental pollutants removal. In addition, the challenges behind the synthesis and use of MXene for decontamination of pollutants were reviewed and reported. • The structural patterns of MXene and its different formula are reviewed. • The synthesis of 2D MXenes by primary techniques (Top-down and Bottom-up) was briefly reviewed. • Mechanical, Electronic, Optical, Oxidative stability, Magnetic nature and Hydrogen storage properties of MXene are reviewed. • This review emphasis the environmental application of toxic pollutant removal on MXene. [ABSTRACT FROM AUTHOR]

MXenes are a rapidly expanding and large family of two-dimensional (2D) materials that have recently garnered incredible research interests for diverse applications domains in various industrial sectors. Owing to unique inherent structural and physicochemical characteristics, such as high surface area, biological compatibility, robust electrochemistry, and high hydrophilicity, MXenes are appraised as a prospective avenue for environmental-clean-up technologies to detect and mitigate an array of recalcitrant hazardous contaminants from environmental matrices. MXene-based nanoarchitectures are thought to mitigate inorganic pollutants via interfacial chemical transformation and sorption, while three different mechanisms, including i) surface complexation and sorption (ii) catalytic activation and removal and (iii) radical's generation-based photocatalytic degradation, are involved in the removal of organic contaminants. Considering the application performance of MXenes on the incessant rise to expansion, in this review, we discuss the wide-spectrum applicability of diverse MXenes-based hybrid nanocomposites in environmental remediation. A brief description related to environmental pollutants, structural properties, chemical abilities, and synthesis route of MXenes is delineated at the start. Afterwards, the adsorption and degradative robustness of MXene-based designer nanomaterials for various contaminants including organic dyes, toxic heavy metals, pesticide residues, phenolics, antibiotics, radionuclides, and many others are thoroughly vetted to prove their potentiality in the arena of wastewater purification and remediation. Lastly, challenges and trends in assessing the wide-range applicability and scalability of MXenes are outlined. Seeing encouraging outcomes in plenty of reports, it can be concluded that MXenes-based nanostructures could be considered the next-generation candidates for water sustainability. • MXenes and MXene-based designer nanomaterials for pollutant mitigation. • Structural characteristics, synthesis route and catalytic properties of MXenes. • MXenes as nano-adsorbents to remediate environmentally toxic pollutants. • Current challenges and future prospect of MXenes are highlighted. [ABSTRACT FROM AUTHOR]

In the middle of May 2018, an unprecedented dust storm occurred in the Shiraz metropolis. After the storm, several samples were collected from dust that settled around the city. These dust samples were analysed for potentially toxic elements (PTEs), rare earth elements (REEs), and radionuclides. This work is the first study that considered rare earth elements (REEs) for source identification and radionuclide contamination of Shiraz dust event. Hysplit model analysis and NASA and NOAA satellite maps illustrated that the air mass affecting Shiraz was moving mainly through the Saudi Arabian deserts. In addition, REE results of the dust that settled in Shiraz showed a trend similar to shale, sandstone, and especially Saudi Arabian soils. Ti/Al (0.01), Fe/Al (0.92), and Mg/Al (0.55) ratios and the values of LaN/SmN (0.91–0.98), GdN/YbN (1.8–2), LaN/YbN (1.7–1.9), HREE/LREE (0.52–0.6), Ce/Ce∗ (1.09–1.13), Eu/Eu∗ (1.03–1.18), Pr/Pr∗ (0.85–0.87), Gd/Gd∗ (1.1–1.15), and MREEs/MREE∗ (4.3–4.5) ratios provided insights into dust sources. These values indicated that Shiraz dust was affected by Asaluyeh and Iraq soils during transport and the main source of the dust that settled in Shiraz on the May 13, 2018 was Saudi Arabian soil. The concentrations of Mo, Cu, Pb, Zn, Ni, Co, Mn, As, Cd, Ti, Al, Sc, and Fe in the settled dust were 0.24, 47.67, 67.33, 244, 70.27, 19.33, 664, 8.39, 0.65, 537.33, 40933.33, 11.54, and 37800 mg/kg, respectively. According to the enrichment factor (EF), coefficient variation, and Positive Matrix Factorization (PMF) model the Mo, Cu, Pb, Zn, and Cd mainly originated from exhaust emissions and industrial activities. The activity concentrations of the radionuclides 7Be, 4 K, 137Cs, and 235U in the Shiraz-settled dust were 814, 421, 14, and 5.4 Bq kg−1, respectively and the activity concentration of 4 K was higher than the crustal average. Health risk assessment indices for the elements considering all three pathways revealed the following trend: dermal contact (HQ derm)< inhalation (HQ inh)< ingestion (HQ ing). The values of HQ inh and HQ ing for children were higher than adults, while the values for the skin adsorption pathway for adults were higher than for children. [Display omitted] • Settled dust was used to assess the Shiraz dust event (May 13th, 2018). • The source was mainly Saudi Arabia with contributions from Iran and Iraq. • Mo, Cu, Pb, Zn, and Cd originated from anthropogenic sources. • Children were more at risk than adults. The main source of the unprecedented dust storm in the Shiraz metropolis on May 13, 2018 was Saudi Arabia. [ABSTRACT FROM AUTHOR]

In this study, a new adsorbent, polyvinyl alcohol (PVA) and graphene oxide (GO), was prepared, characterized and used for the removal of Sr2+ from aqueous solution. In PVA/GO composite, the inter-lamellar spacing of adjacent GO layers was dramatically enlarged due to the intercalation of PVA molecules, such a unique architecture significantly mitigated the aggregation of GO layers, which facilitated the accessible exposure of active sites and the mass transfer of strontium ions (Sr2+), thus enhancing the adsorption capacity toward Sr2+. The adsorption of Sr2+ by PVA/GO composite conformed to the pseudo second-order kinetic model (R 2 = 0.9994), the Langmuir model (R 2 = 0.9042), and the Freundlich model (R 2 = 0.9598). The complexation interaction between Sr2+ and oxygen atoms/π-electron domain of PVA/GO composite was primarily responsible for the adsorption mechanism, based on the characterization results of X-ray photoelectron spectroscopy (XPS), scanning electron microscope equipped with energy dispersion spectroscopy (SEM-EDS) and powder X-ray diffraction (PXRD). • PVA/GO aerogel was prepared, characterized and used for Sr(II) sorption. • Hydrogen bond was primary driving force in the fabrication of PVA/GO aerogel. • PVA/GO aerogel exhibited good adsorption performance for Sr(II). • PVA/GO aerogel with a monolith morphology can be readily separated from solution. • The interaction between Sr(II) and –COOH/π-electron was responsible of Sr sorption. [ABSTRACT FROM AUTHOR]

Various environmental pollutants (e.g., air, water and solid pollutants) are discharged into environments with the rapid development of industrializations, which is presently at the forefront of global attention. The high efficient removal of these environmental pollutants is of important concern due to their potential threat to human health and eco-diversity. Advanced nanomaterials may play an important role in the elimination of pollutants from environmental media. MXenes as the new intriguing class of graphene-like 2D transition metal carbides and/or carbonitrides have been widely used in energy storage, environmental remediation benefitting from exceptional structural properties such as highly active sites, high chemical stability, hydrophilicity, large interlayer spacing, huge specific surface area, superior sorption-reduction capacity. However, the comprehensive investigation concerning the removal of various environmental pollutants on MXenes is yet not available up to date. In this review, we summarized the synthesis and properties of MXenes to demonstrate the key roles in ameliorating their adsorption performance; then the recent advances and achievements in environmental application of MXenes on the removal of gases, organics, heavy metals and radionuclides were comprehensively reviewed in details; Finally, the formidable challenges and further perspectives regarding utilizing MXene in environmental remediation were proposed. Hopefully, this review can provide the useful information for environmental scientists and material engineers on designing versatile MXenes in actual environmental applications. [Display omitted] • The synthesis and properties of MXene was briefly summarized. • The removal of environmental pollutants on MXene was detailed reviewed. • This review is crucial for application of MXene in actual remediation. [ABSTRACT FROM AUTHOR]

The Arctic region is substantially a pristine area, but this unique part of the globe has also been contaminated by anthropogenic radioactive nuclides, and now there is still measurable activity of anthropogenic isotopes, even though more than 50 years have passed since the main source. Radionuclides in the Arctic, especially 90Sr have seldom been studied despite their considerable environmental importance. This manuscript covers the results of 90Sr and 137Cs measurements in soil and lichen Cetrariella delisei collected from the Svalbard in 2012. In both lichen thalli and surface soils high activities of 90Sr and 137Cs were recorded and ranged between 3.69 and 28.1 Bq kg−1 90Sr and 5.38–280.1 Bq kg−1137Cs in thalli and between 4.53 and 12.78 Bq kg−1dw 90Sr and 60.6–426.1 Bq kg−1dw 137Cs in surface soil layer. The activity of 90Sr and 137Cs in lichen thalli was influenced by distance from the glacier. This showed that during radionuclide biomonitoring of particular area with the use of lichens, it is important to take into account influence of environmental variability on radionuclides contents. • 90Sr and 137Cs were investigated in soil and Cetrariella delisei from the Arctic. • Activity in Cetrariella delisei were dependent of distance from the glacier. • 137Cs and 90Sr activity in surface soil did not present clear pattern. • Environmental variability may impact accumulation of 137Cs and 90Sr by lichens. [ABSTRACT FROM AUTHOR]

Sorption of radionuclides on mineral surfaces retards their migration in the environment of a repository. Presence of organic ligands, however, affects sorption and consequently influences their transport behavior. In this study, we quantify the sorption of Eu(III) onto quartz surfaces as a function of pH in the absence and presence of diethylenetriaminepentaacetic acid (DTPA). Batch sorption experiments show a pH-dependent sorption of Eu(III) on quartz. The presence of DTPA results in slightly higher sorption of Eu(III) at neutral to slightly acidic pH and considerably lower sorption at alkaline conditions. Sorption experiments were simulated using the Diffuse Double Layer Model (DDLM) with single sorption sites (≡QOH) and monodentate surface complexation. The reactions were established based on the aqueous speciation calculation under the experimental conditions, and the thermodynamic constants of surface reactions were obtained and refined by numerical optimization. Results of surface complexation modeling show the formation of a surface species ≡QOHEuDTPA 2- , explaining the elevated sorption of Eu(III) at neutral to slightly acidic pH. In contrast, dissolved EuDTPA 2- complex species are present at alkaline pH, resulting in an enhanced mobility of Eu(III)., (Copyright © 2019 Elsevier Ltd. All rights reserved.)