The aim of this paper is to assess the radon concentration of surface and ground waters around Bismuth mining site located in Edu, Kwara State, Nigeria, in order to ascertain its radiological risk. Seventeen (17) water samples were collected and analyzed for radon concentration using a calibrated Rad7-Active Electronic Detector Durridge. The Radon concentration for surface water ranged from 16.23±3.45 Bq/l to 24.71±4.51 Bq/l with a mean of 19.14±3.98 Bq/l while that of ground water ranged from 21.59±3.29 to 27.93±5.74 Bq/l with a mean of 24.16±4.21 Bq/l. The concentration results were used to estimate the annual effective doses. The mean total annual effective dose obtained by summing the dose due to inhalation and ingestion for surface water samples were 187.97 μSvy-1, 257.84 μSvy-1 and 292.77 μSvy-1 for adult, children and infants respectively. Also, the mean effective doses for ground water samples were of 237.25 μSvy-1, 325.44 μSvy-1 and 369.53 μSvy-1 for adult, children and infants respectively. Both the radon concentration and the effective dose due to its inhalation and ingestion were higher than the recommended limit of 11.1 Bq/l and 100 μSvy-1 respectively for all samples. Therefore, consumption of the water in this area poses serious health risk as the water is not safe for all age groups considered. Therefore, it is advised that the water from both sources be treated before consumption.

2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) was difficult to degrade in sediments. In this study, the environmental behavior of BDE-47 with/without the effect of benthos (Tubificidae Limnodrilus) and electron acceptors in sediments was investigated using C-14 tracer. Generally, extractable residues of BDE-47 were dominant in sediment and posed high environment risk. The amount of non-extractable residues (NERs) accounted for 39.0% of initial radioactivity in oxic sediments was significantly higher than those in anoxic sediments (17.6%). Most of NERs were localized in the humin fraction and presented as sequestrated forms. Under oxic conditions, the present of Limnodrilus significantly increased the proportion of NERs in sediment. Limnodrilus accumulated 34.2% of initial radioactivity. Under anoxic conditions, the addition of iron (Ⅲ) [Fe(III)], sulfate and nitrate reduced the environmental risk of BDE-47 with the increase of NERs formation, while manganese (IV) [Mn(IV)] addition had no effect on the formation of NERs. The present of Limnodrilus and electron acceptors promoted the production of metabolites. Meanwhile, BDE-47 changed the microbial community structure of sediments. These findings indicated that the environmental behavior and risk of BDE-47 was affected by benthos and electron acceptors, and the high proportion of sequestrated NERs posed high bioactivity and toxic threat to ecological environment.

Surface sediment from the Boka Kotorska Bay (Adriatic Sea) was analyzed for the content of technogenic cesium (¹³⁷Cs) and naturally occurring (⁴⁰K, ²²⁶Ra, ²³²Th, ²³⁸U) radionuclides. The activity concentrations of the radionuclides have been correlated with the major elements (Si, Al, Ca, Fe, K, Mg, Ti, P, Mn) content of sediment samples. The spatial interpolation identified primordial radioactivity more pronounced in the inland of the bay. Correlation and hierarchical cluster analyses clearly distinguished ²²⁶Ra, ²³²Th, and ²³⁸U from ¹³⁷Cs. In addition, a strong association between primordial radionuclides and most major elements was found. Positive matrix factorization apportioned technogenic and natural radionuclides sources, while Si and Ca were separated from other elements. Radiological hazard parameters (Raₑq, D, AEDE, Hᵢₙ, Hₑₓ, AGDE, AUI) that include the doses and indices, and the excess lifetime cancer risk indicate that the risk in the studied area due to gamma radiation is within the acceptable level.

In this paper, a marine environmental sensitivity index system was constructed based on three factors: the marine biological species sensitivity, the marine ecological value sensitivity and the social and economic sensitivity. Combined with numerical simulations of ¹³⁷Cs in the Beibu Gulf under the condition of a level-7 nuclear accident, a comprehensive risk assessment of marine radioactivity under the simulated accident in the Beibu Gulf was carried out. The results show that the areas at high risk and medium-to-high risk to marine radioactivity are mainly concentrated within 30 km of the Fangchenggang Nuclear Power Plant. The medium-risk areas are mainly distributed in sea areas within 30–50 km of the nuclear power plant, and the other sea areas are low-risk areas. The distribution of the risk sources and the characteristics of the regional tidal currents are the main factors affecting the magnitude and distribution of the comprehensive risk of regional marine radioactivity.

Anthropogenic radionuclides are among those human impacts, which can be seen widely in the marine and terrestrial ecosystems. Fallout from the 1986 Chernobyl nuclear power plant accident has rendered the Baltic Sea as the most polluted marine body in the world with respect to ¹³⁷Cs. This research investigated sediment cores from 56 sites around the Gulf of Bothnia, Baltic Sea. Radioactivity from ¹³⁷Cs in sediments has generally declined due to natural/radioactive decay of ¹³⁷Cs over the last decades. However, ¹³⁷Cs contents in subsurface sediments remain at elevated levels compared to pre-Chernobyl levels. The highest ¹³⁷Cs activity contents in subsurface sediments (>4000 Bg kg⁻¹) occur in coastal areas including estuaries. These areas often experience severe anthropogenic pressure. The southern Bothnian Sea, Kvarken archipelago, and southern Bothnian Bay all show elevated ¹³⁷Cs values in subsurface sediments. Sedimentary ¹³⁷Cs can also help constrain recent rates of sedimentation. Post-Chernobyl sedimentation rates in the Gulf of Bothnia varied from 0.1 to 4.8 cm/year with an average sedimentation rate of 0.54 cm/year.

In this work data of salinity, temperature, suspended particulate matter (SPM), chlorophyll-a, and phytoplankton concentration in the Gibraltar Strait coast, in the confluence of the Mediterranean Sean and the Atlantic Ocean, were analyzed together with ²¹⁰Po, ⁴⁰K, ²¹⁰Pb and ²³⁴Th activity concentration in different types of bivalve molluscs at the same time-period. The physicochemical parameters were evaluated using the Copernicus Marine Environment Monitoring Service (CMEMS) products based on satellite observations. A multivariate statistical analysis, including contrasted natural radioactivity contents, allowed the discrimination of bivalve molluscs from Atlantic and Mediterranean coasts. Additionally, a cluster analysis determined a highly significant negative correlation ²¹⁰Po concentration in molluscs and phytoplankton concentration suggesting that phytoplankton concentration in the water column is a determinant factor to regulate ²¹⁰Po concentration in those animals. These results introduce a useful tool to calculate the radiological doses in seafood from chlorophyll satellite image.

This paper studies the activity of natural and technogenic radionuclides in bottom sediments and surface water of the Pechora River estuary, which is the largest Arctic river within the European part of Russia. The relevance of conducting radioecological studies of this region is associated with active oil and gas activities in the Pechora basin and the presence of potential sources of radiation hazard. The average activities of ¹³⁷Cs, ²²⁶Ra, ²³²Th, and ⁴⁰K in bottom sediments were 0.16, 18.72, 13.36, and 373.59 Bq·kg⁻¹, respectively. The average activity of ²²⁶Ra in the bottom sediments of the Pechora delta was two times higher than in other rivers of the Arctic basin of the European part of Russia, which is associated with oil and gas activities that are carried out in the Pechora basin. This is due to the fact that the decay products of uranium are the main by-products of oil and gas production. The specific activity of technogenic ¹³⁷Cs in bottom sediments of the Pechora River delta was low and did not exceed 2.2 Bq·kg-1. We did not detect any radioactive ⁹⁰Sr in bottom sediments. The low ¹³⁷Cs activity in the bottom sediments of the Pechora delta was associated with both the larger granulometric composition of the sediments in comparison with the estuaries of the Siberian rivers, and with low concentrations of ¹³⁷Cs in the terrigenous material (soil) entering the river from the catchment area. This was due to the low levels of ¹³⁷Cs contamination in the soil of the Pechora river basin. We did not find any negative radiation effects of the underground nuclear explosion “Pyrite” carried out in the northern part of the delta, since there were no other technogenic radionuclides. The values of the radionuclides ³H, ¹³⁷Cs, ²²⁶Ra, ²³²Th and ⁴⁰K, as well as the total alpha activity in the surface waters of the Pechora River delta, turned out to be below the detection limit. In surface waters, we were able to determine only the total beta activity, which varied over a range from 19.6 to 59.6 Bq·m⁻³ with an average value of 33.9 Bq·m⁻³, which was significantly lower than the radiation safety standards. The values of the radiation hazard parameters were below the world average levels and were not significantly hazardous to the health of people living in the area of the Pechora River delta. We concluded that at present, in the Pechora River delta, there are pastures for reindeer with low levels of natural and man-made radioactivity. These conducted studies are the source material in a series of comprehensive studies of the current radioecological state of the tundra territories of the European part of Russia.

Areas in central Norway were heavily contaminated with fallout from the Chernobyl accident in 1986. In this study, we assess ¹³⁷Cs in surface sediments and sediment cores collected in the Vefsnfjord in Nordland county. Concentrations of ¹³⁷Cs in surface sediments ranged from 159 to 191 Bq kg⁻¹ dry weight (d.w.). Sub-surface peaks of ¹³⁷Cs were observed in all cores, with a maximum concentration of 432 Bq kg⁻¹ d.w. Given that little is known about the distribution of naturally occurring radionuclides in Norwegian fjords and coastal areas, a better understanding of the total burden of radioactivity is important for the Norwegian fishing and aquaculture industries. Therefore, analyses of the natural radionuclides ⁴⁰K, ²²⁶Ra, ²²⁸Ra and ²¹⁰Pb were included in the study. Analyses of total sulphur (TS), total carbon (TC), total organic carbon (TOC) and grain size distribution have been performed to provide a sedimentologic context for interpreting the radionuclide results.

Impact assessment of building materials is a focused topic in the field of radioecology. A radiological survey has conducted to monitor radioactivity of most common building materials in Semnan Province, Iran, and assess the radiation risk. Activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K were measured in 29 samples including nine commonly used building materials that were collected from local suppliers and manufacturers, using a high purity germanium gamma-ray detector. The activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K varied from 6.7±1 to 43.6±9, 5.9±1 to 60±11, and 28.5±3 to 1085±113 Bq kg⁻¹ with averages of 26.8±5, 22.7±4, and 322.4±4 Bq kg⁻¹, respectively. By applying multivariate statistical approach (Pearson correlation, cluster, and principal component analyses (PCA)), the radiological health hazard parameters were analyzed to obtain similarities and correlations between the various samples. The Pearson correlation showed that the ²²⁶Ra distribution in the samples is controlled by changing the ²³²Th concentration. The variance of 95.58% obtained from PCA resulted that the main radiological health hazard parameters exist due to the concentration of ²²⁶Ra and ²³²Th. The resulting dendrogram of cluster analysis also shows a well coincidence with the correlation analysis.

Acid mine drainage (AMD) remediation by red mud (RM) can benefit process sustainability and waste valorization. Though the AMD properties upon using RM have been broadly investigated, the key features and the environmental stability of spent RM are poorly defined. The current study aimed to compare the AMD neutralization and metal removal potential of the fresh (FRM) and aged (ARM) Bayer red mud and evaluate the textural, mineralogical, chemical, radiological properties of solid residues, and the stability of toxic elements. The FRM had larger particles and exhibited higher pH, iron oxide content, and radioactivity than ARM, which could be driven by ARM leaching and settling inside the tailings pond. FRM displayed marginally higher neutralization and metal removal capacity than ARM. Reaction with AMD led to partial dissolution of cancrinite minerals without significant changes in the particle size distribution. The leachability of investigated toxic elements (As, Ba, Cd, Cr, Cu, Ni, Pb, Se, Zn) from neutralization residues complied with the limits set for inert waste by the EN 12457–2 test. Owing to the RM neutralization, the leachability of Al, As, Cr, and V decreased with respect to pristine samples. While Zn and Mn sorbed from AMD were stable following SPLP and EN 12457–2 tests, the sequential extraction revealed increased environmental availability, posing a potential risk during disposal or application if accompanied by a decline in pH. The slight increase in radioactivity upon RM neutralization indicates that changes in radionuclide inventory should be monitored when using RM in neutralization.