Variations of 210Po and 210Pb in various marine organisms from Western English Channel: contribution of 210Po to the radiation dose

Theoretical Prediction of the 210 Pb Burden in the Skeleton from Radon Exposure and Other Intake Routes

ABSTRACT

The 210 Pb burden in the skeleton is a measurement value suitable for the estimation of the cumulative exposure to radon, based on which the resultant risk of lung cancer can be derived. There have been a handful of studies that successfully measured 210 Pb activity in the bones of volunteers who had chronic exposure to high concentrations of radon occupationally or in their residences. However, the quantitative relationship between measured 210 Pb activity and radon exposure remains elusive. Herein, we investigate the origin of the skeletal burden by employing the biokinetic model recommended by the International Commission on Radiological Protection and modeling various routes of intake. First, the baseline 210 Pb burden for the general public regarding eating assorted foodstuffs and breathing normal air is obtained. It is found that this baseline burden ranges between 7.3 to 46.5 Bq for a 50-y-old (male) person, which characterizes a large variance due to the uncertainty of each route of intake. Next, we concentrate on radon exposure by referring to two experimental studies where the accounts of exposure and the measured 210 Pb burden for each volunteer are documented in detail. From comparing our prediction and measurements, it is found that exposure to higher concentration of radon is the most significant source of 210 Pb intake, and the quantitative differences can be reasonably explained by the uncertainty resulting from regular intake routes. This study establishes the theoretical foundation for assessing one's risk of lung cancer due to radon exposure by measuring the 210 Pb burden in bones.

Characteristics and radiological hazard assessment of 210Po in tilapia (Oreochromis niloticus) in Vietnam

210Po is one of the most toxic natural radionuclides. This isotope's characteristics and radiological hazard assessment have been concerned in different objects. In this study, the 210Po activities were determined in different tilapia organs/parts of 20 sample groups by alpha spectrometry. The 210Po activities in muscle, bone, intestine organs, and stomach contents unevenly distributed with a wide range from 0.5 ± 0.2 to 2.8 ± 0.4 and 1.4 ± 0.2 Bq·kg-1 wet.wt on average, from 0.6 ± 0.3 to 6.3 ± 0.7 and 3.5 ± 0.4 Bq·kg-1 wet.wt on average, from 46.3 ± 2.9 to 263 ± 9.7 and 115 ± 6 Bq·kg-1 wet.wt on average, and 20.9 ± 1.2 to 800 ± 29 and 197 ± 9 Bq·kg-1 wet.wt on average, respectively. The average 210Po activities in different parts of tilapia trend in order of CMuscle < CBone < CIntestine < CStomach contents. Insignificant correlations were observed between 210Po activities in tilapia organs with their total fish mass. The result could depend on feeding types, diet, different nutrient levels, metabolism, and excretion of 210Po in different ages. The concentration ratios (CRs) of tilapia muscle and bone organs were recorded with low values, while it was far greater than the CRs for the intestine organ. Annual committed effective doses contributing from 210Po concentration due to tilapia fish consumption were within the allowable limits for muscle and bone organs, while those values for intestine organs were far higher than the allowable limit value (assuming similar amount consumption of 30 kg·year-1 for each organ). The Erica tool was used to estimate the dose and risk to tilapia from 210Po exposure. Based on the calculated results, it can be seen that there was insignificant concern for tilapia due to ionizing radiation in the study area.

A review of 210Pb and 210Po in moss

Among environment contaminants, 210Pb and 210Po have gained significant research attention due to their radioactive toxicity. Moss, with its exceptional adsorption capability for these radionuclides, serves as an indicator for environmental 210Pb and 210Po pollution. The paper reviews a total of 138 articles, summarizing the common methods and analytical results of 210Pb and 210Po research in moss. It elucidates the accumulation characteristics of 210Pb and 210Po in moss, discusses current research challenges, potential solutions, and future prospects in this field. Existing literature indicates limitations in common measurement techniques for 210Pb and 210Po in moss, characterized by high detection limits or lengthy sample processing. The concentration of 210Pb and 210Po within moss display substantial variations across different regions worldwide, ranging from Collapse

Key Words

• (210)Pb
• (210)Po
• Environmental contamination
• Measurement method
• Moss bioindication

Collapse

MESH Headings

• Lead Radioisotopes/analysis
• Polonium/analysis
• Bryophyta/chemistry
• Radiation Monitoring/methods

Collapse

Grants Collapse

Affiliation(s)

Chenlu Ding College of Nuclear Technology and Automation Engineering, Chengdu University of Technology, Chengdu, 610059, Sichuan, PR China
Qiang Yang College of Nuclear Technology and Automation Engineering, Chengdu University of Technology, Chengdu, 610059, Sichuan, PR China; Sichuan Cancer Hospital & Institute, Affiliated Cancer Hospital of University of Electronic Science and Technology of China, Chengdu, 611731, PR China.
Xue Zhao Chongqing Radiation Environment Supervision and Management Station, Chongqing, 400015, PR China
Lipeng Xu Sichuan Cancer Hospital & Institute, Affiliated Cancer Hospital of University of Electronic Science and Technology of China, Chengdu, 611731, PR China
Hui Tang College of Nuclear Technology and Automation Engineering, Chengdu University of Technology, Chengdu, 610059, Sichuan, PR China; Sichuan Management and Monitoring Center Station of Radioactive Environment, Chengdu, 611139, PR China
Zhengshang Liu College of Nuclear Technology and Automation Engineering, Chengdu University of Technology, Chengdu, 610059, Sichuan, PR China
Juan Zhai College of Nuclear Technology and Automation Engineering, Chengdu University of Technology, Chengdu, 610059, Sichuan, PR China
Qingxian Zhang College of Nuclear Technology and Automation Engineering, Chengdu University of Technology, Chengdu, 610059, Sichuan, PR China

Collapse

Assessing Metal Toxicity on Crustaceans in Aquatic Ecosystems: A Comprehensive Review

Residual concentrations of some trace elements and lightweight metals, including cadmium, copper, lead, mercury, silver, zinc, nickel, chromium, arsenic, gallium, indium, gold, cobalt, polonium, and thallium, are widely detected in aquatic ecosystems globally. Although their origin may be natural, human activities significantly elevate their environmental concentrations. Metals, renowned pollutants, threaten various organisms, particularly crustaceans. Due to their feeding habits and habitat, crustaceans are highly exposed to contaminants and are considered a crucial link in xenobiotic transfer through the food chain. Moreover, crustaceans absorb metals via their gills, crucial pathways for metal uptake in water. This review summarises the adverse effects of well-studied metals (Cd, Cu, Pb, Hg, Zn, Ni, Cr, As, Co) and synthesizes knowledge on the toxicity of less-studied metals (Ag, Ga, In, Au, Pl, Tl), their presence in waters, and impact on crustaceans. Bibliometric analysis underscores the significance of this topic. In general, the toxic effects of the examined metals can decrease survival rates by inducing oxidative stress, disrupting biochemical balance, causing histological damage, interfering with endocrine gland function, and inducing cytotoxicity. Metal exposure can also result in genotoxicity, reduced reproduction, and mortality. Despite current toxicity knowledge, there remains a research gap in this field, particularly concerning the toxicity of rare earth metals, presenting a potential future challenge.

A review of natural and anthropogenic radionuclide pollution in marine bivalves

Radionuclide contamination in food is a public health issue. Bivalves are known to accumulate relatively high levels of radionuclides. Despite many relevant reports, this information is poorly organized. Therefore, in this study, we conducted a comprehensive scientific review of radionuclides in marine bivalves. In general, the accumulation of radionuclides in bivalves is highly species and tissue-specific, which may be due to the different biological half-life of radionuclides in different species and tissues. The trophic pathway is the main pathway for the accumulation of most radionuclides in bivalves, with polonium-210 (210Po) and lead-210 (210Pb) potentially selectively accumulating in the digestive glands, while 134Cs and 137Cs selectively accumulating in the adductor muscle and mantle. Some other radionuclides (radium-226 (226Ra) and strontium-90 (90Sr)) are absorbed along with other minerals (e.g. Calcium) and selectively accumulate in bivalve shells. The information in this study can provide an overview of radionuclide contamination in marine bivalves.

Radiotoxic 210Po concentration in the Mediterranean Sea sediment and radiation risk assessment of biota

This research presents the levels and distribution of 210Po in different sediments of the northeastern coast of the Mediterranean Sea. The 210Po activity concentrations were measured using an alpha spectroscopy system. The activity concentrations of 210Po in the sediment samples were in the range between 20.5 ± 0.7 and 92.8 ± 1.6 Bq kg-1 dw with an average of 48.2 ± 1.4 Bq kg-1 dw. The microorganism-enriched sampling sites (bedrock sites) indicated low 210Po concentration than sandy coastal sites. As a result of these measurements, the RESidual RADioactivity (RESRAD) biota code was applied to calculate the tissue concentration rate (CR), internal dose rate, external dose rate, and total dose rate of the exposed tissues. The total dose rates of aquatic animals were found higher than that of riparian animals. The 210Po sediment resource doses to aquatic and riparian animals were found less than the dose level recommended by International Commission on Radiological Protection (ICRP).

Factors Contributing to Accumulation of 210Po in Freshwater Fishes in Dong Thai Lake, Vietnam and Radiological Hazard Assessment

210Po (polonium), one of the most toxic naturally occurring radionuclides, is well-known as a common natural radionuclide in fish species. Human consumption of 210Po-contaminated fish could result in a significant internal dose. This study determined by alpha spectrometry the 210Po activity in sixteen selected fish species with different living behaviors (pelagic, demersal), trophic positions (herbivores, carnivores, omnivorous), and masses in Dong Thai Lake, Hanoi, Vietnam. The min, max, and average of the 210Po concentration of sixteen fish species were 0.80 ± 0.44, 12.7 ± 0.20, and 3.54 ± 0.31 Bq kg-1, respectively. Regarding the different living behaviors, trophic positions, and masses, the results showed trending of 210Popelagic > 210Podemersal; 210Poherbivores < 210Pocarnivores < 210Poomnivorous and 210Po<0.2 kg > 210Po0.2-1 kg > 210Po>1 kg, respectively. The 210Po concentrations in muscle tissue were greater in fish species with a small mass, omnivorous trophic position, and pelagic living behavior relative to demersal fish with a larger mass that were herbivores or carnivores. In addition, the results showed an uneven distribution of 210Po activities in atmospheric aerosols, terrestrial soils, surface waters, and lake sediments in the study area. The primary source of 210Po could be supplied from atmospheric aerosols and/or terrestrial soils in the study area. The 210Po annual effective dose for adults due to fish consumption has been calculated with a range from 20 to 400 µSv y-1 and 111 µSv. y-1 on average, and it is far below the allowable limits of 1000 µSv y-1.

Characteristics of 210Po in Asian overbite clam (Potamocorbula laevis) from the coastal area at Thai Binh province, Vietnam

210Po concentration in the edible muscle tissue and digestive diverticulum organs of Asian overbite clam at the near-shore Thai Binh, Vietnam was analyzed using alpha detectors. The 210Po activity in muscle tissue and digestive diverticulum organs ranged from 5 ± 1 to 178 ± 10 and from 118 ± 7 to 812 ± 12 Bq.kg-1 with the average value of 25 and 324 Bq.kg-1, respectively. Results showed that 210Po activity in the digestive diverticulum was significantly higher than in the muscle tissue. There was a slightly inverse correlation between 210Po activity in muscle tissue, digestive diverticulum, and clam weight and size. The annual committed effective dose was calculated from 210Po due to the consumption of Asian overbite clam for adults in the study area was higher than the guideline value of 0.2 - 1 mSv.y-1.

Effect of Radionuclides and Trace Elements on Antioxidant System of Brown Seaweeds

Ecological effects in marine living can be understood via the determination of antioxidant molecules in aquatic organisms against pollutants. This study aims to evaluate the radionuclides and trace element stress with response molecules. Cystoseira crinita and Halopteris scoparia have been chosen as study materials because of their susceptibility to pollution. The radionuclides ²¹⁰Po, ²³⁸U, ²³²Th and ⁴⁰K and trace elements Al, Fe, Mn, Cr, As, Zn and Pb levels were analysed as well as antioxidants and antioxidant enzymes in two brown algae, seasonally. Marine pollutants in terms of radionuclides and trace elements were correlated with antioxidant molecules in these species and may be used as biomarkers for assessing the radioactive stress. The ²¹⁰Po and Mn concentrations in C. crinita seem to activate catalase (CAT) and superoxide dismutase (SOD) enzyme activities while ²¹⁰Po concentrations inclined the proline amount in H. scoparia. This study demonstrated the radiation stress-induced the antioxidant defence system in macroalgae, the primary producers of the marine environment.

Radiological dose and associated risk due to 210Po in commercial inter-tidal bivalves of southwest (Arabian Sea) coast of India

The activity concentration of ²¹⁰Po was determined in edible tissues of commercial bivalves on the southwest coast of India. The ²¹⁰Po activity ranged from 38.3 ± 6.9 Bq kg^-1 to 91.2 ± 18.6 Bq kg^-1. The annual committed effective dose (ACED) and lifetime carcinogenic risk (LCR) were calculated for different age groups to determine the potential health risk associated with bivalve consumption. The average ACED ranged from 81.5 to 194.1 μSv y^-1, with the 10th and 95th percentiles being 68 and 261 μSv y^-1, respectively. Lifelong mortality risk (LMTR) values ranged from 1.2 × 10^-3 to 2.9 × 10^-3, while lifetime morbidity risk (LMBR) values ranged from 1.9 × 10^-6 to 4.9 × 10^-6. The effective dose was found to be within the UNSCEAR limits.

Evaluation of the radiological dose due to 210Po in commercial clupeid fish collected in the near-shore environment of the high background natural radiation area (HBNRA) on the southwest coast of India

In this study, we quantified the tissue concentration of ²¹⁰Po in a variety of commercial sardine fish species of the family Clupeidae from an area of high background natural radiation area on the southwest coast of India. The smooth belly sardine Amblygaster leiogaster had the lowest ²¹⁰Po concentration in its muscle (45.6 ± 7.9 Bq kg^-1 fresh), while the goldstripe sardine Sardinella gibbosa had the highest (103.4 ± 10.1 Bq kg^-1 fresh). The Annual Committed Effective Dose (ACED) of fried sardine and sardine curry were 134.3-304.3 μSv y^-1 and 226.6-513.5 μSv y^-1, respectively. Of the ²¹⁰Po loss, 20 % was due to frying and 10 % to preparing sardine curry. The effective dose was found to be globally comparable and well below the world limit. Consumption of sardines containing ²¹⁰Po would not pose a health hazard to the residents of Manavalakurchi.

Assessment of Sargassum sp., Spirulina sp., and Gracilaria sp. as Poultry Feed Supplements: Feasibility and Environmental Implications

Eutrophication, coupled with ocean acidification and warming, results in an increased concentration of marine algae, severely impacting some regions. Several algae are a rich source of protein and minerals. Marine algae are rich in bioactive molecules with antioxidants, anti-inflammatory, anti-fungal, and antimicrobial properties. These properties make them attractive for usage in the pharmaceutical industry. This study evaluated Sargassum sp., Spirulina sp., and Gracilaria sp. for use as poultry feed. Chemical analyses show that crude protein (CP) in analyzed algae was 9.07–63.63%, with a fiber content of 0.15–17.20%, and a crude fat range of 0.152–2.11%, suggesting that algae can partially substitute imported protein sources used for poultry feed. A rapid impact assessment matrix (RIAM) was used to assess the environmental footprint of algae usage in poultry feed. The environmental assessment results show promising opportunities to help harvest the algae from the marine area. However, the feasibility of establishing outdoor algal ponds is not environmentally viable in the Middle East.

Background 210Po activity concentrations in Greenland marine biota and dose assessment

Polonium-210 (²¹⁰Po) is a radionuclide sentinel as it bioaccumulates in marine organisms, thereby being the main contributor to committed dietary doses in seafood consumers. Although seafood and marine mammals are an important part of the traditional Inuit diet, there is a general lack of information on the ²¹⁰Po concentrations in the Greenlandic marine food chain leading to the human consumer. Here, we determine background ²¹⁰Po concentrations in edible parts of different marine organisms from Greenland and provide a dose assessment. Blue mussels (Mytilus edulis), organs of ringed seal (Pusa hispida) and polar bear (Ursus maritimus) displayed significantly elevated ²¹⁰Po concentrations in respect to all other studied organisms (p < 0.001). ²¹⁰Po concentrations ranged from 0.02 Bq kg^-1, w.w. in Greenland halibut (Reinhardtius hippoglossoides) muscle to 78 Bq kg^-1, w.w. and 202 Bq kg^-1, w.w. in ringed seal muscle and kidneys, respectively. ²¹⁰Po concentration ratio for edible parts increases in the order bladderwrack (Fucus Vesiculosus), northern shrimp (Pandalus borealis), blue mussels, and from fish species to ringed seal and polar bear. ²¹⁰Po distribution in fish, ringed seal, and polar bear follows a general pattern, the lowest concentrations were in muscle, and the highest concentrations were in the organs involved in metabolism. The derived ²¹⁰Po annual absorbed dose in edible parts of studied marine organisms are several orders of magnitude lower than the recommended dose rate screening value of 10 μGy h^-1. Effective doses from intake of ²¹⁰Po to Greenland average children (1.4 mSv y^-1), and high seafood and marine mammal consumers (2 mSv y^-1 for adults and 3.6 mSv y^-1 for children) are higher than the world average annual effective dose due to ingestion of naturally occurring radionuclides.

Distribution, annual committed effective dose, and health safety assessment of 210Po in marine biota from Kalpakkam coast, Bay of Bengal

Seafood, intertidal biota, beach sediment, and seawater from Kalpakkam coast, Bay of Bengal were analyzed for ²¹⁰Po to evaluate the internal exposure and other radiological safety aspects. Kalpakkam houses various nuclear power generation facilities on its coast. The activity concentration of ²¹⁰Po was more pronounced in the intertidal organisms. Pelagic planktivorous fishes have the highest activity of the non-technogenic radionuclide, followed by the detrital feeders, benthic planktivores, benthic carnivores, and pelagic carnivore fishes. The affinity of ²¹⁰Po to organic detrital matter and planktonic organisms has led to a higher accumulation of radionuclide in planktivorous fishes. Activity concentration of ²¹⁰Po in seafood ranged between 1.13 ± 0.3 and 96.71 ± 1.6 Bq kg^-1 (Becquerel/kilogram). In seaweeds and gastropods, it ranged from 2.09 ± 0.2 to 8.21 ± 0.6 and from 9.31 ± 0.7 to 21.58 ± 1.2 Bq kg^-1, respectively. The committed effective dose (CED) of ²¹⁰Po in seafood varied from 31.18 to 456.68 μSv yr^-1 (microSievert/year). Radiological hazard parameters, such as activity intake, CED in consumption, of the seafood from this coast are within the acceptable levels prescribed by the International Commission on Radiological Protection and US Environmental Protection Agency.

Correlation of phytoplankton satellite observations and radiological doses in molluscs

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.

Distribution and annual committed effective dose assessment of 210Po in popular marine species at the near-shore Binh Thuan province, Vietnam

²¹⁰Po concentration in thirty popular marine species (twenty five fishes, four bivalves and one crab) with different habitats, feeding types, and trophic levels at the near-shore Binh Thuan, Vietnam was analyzed using the alpha detectors. The ²¹⁰Po activities were widely ranged from 3.07 ± 0.18 in a fish species (Bumpnose trevally) to 78.6 ± 5.3 Bq/kg w.w in a bivalve species (Green mussel) with the average value of 16.6 Bq/kg w.w. The results showed that the species with lower trophic level value have higher ²¹⁰Po concentration. Regarding the feeding types, the ²¹⁰Po concentration in the omnivorous species is about 2.9 times higher than in the carnivorous species. The species living in demersal zone accumulated a high ²¹⁰Po in comparison with species living in reef-associated and pelagic-neritic zones. The calculated annual committed effective dose from ²¹⁰Po due to the ingestion of seafood from demersal zone and bivalve species of the area was significant high.

Natural Polonium-210 in Bivalve Species in Peninsular Malaysia Waters as Recent Pollution Indicator

Po-210 is an alpha rays emitter in U-238 decay series and a natural radionuclide found in the ocean, and bivalve is the best biological indicator compared to the other organisms because of their feeding methods that are filter-feeding and suspension-feeding. They are able to accumulate toxic substances from marine environment in their tissue and researches were conducted in edible tissues of Meretrix meretrix, Perna virid, Glauconome virens, Anadara granosa, Anadara ovalis, Pholas orientalis, Donax sp., Polymesoda bengalensis, Phapia undulata, and Tellina virgate. Result showed Po-210 activity distributions were ranging from 2.61 ± 1.50 to 517.46 ± 56.64 Bq/kg. The lowest value of Po-210 activity recorded in Anadara granosa and the highest value recorded in Donax sp. Small-sized of bivalve species contained higher Po-210 activity than the larger one. Higher Po-210 contents in bivalve obtained from the west coast of Peninsular Malaysia might be closely related to anthropogenic factors from the coastline. This study also found that Donax sp. is able to be a good indicator of environmental pollutants as it accumulates Po-210 in higher concentrations than other bivalve species. Donax sp. can be found in several parts of Malaysia and available in large quantities but it appears to be seasonal. While for seafood safety monitoring, Anadara granosa is capable of becoming a good benchmark for seafood security as it found in most parts of Malaysia. It is not seasonal and a kind of Malaysian favorite seafood.

A review of radioactivity in the Gulf region

The region around the Gulf is moving toward a nuclear energy option with the first nuclear power plant now operational in Bushehr, Iran. Others are soon to be commissioned in Abu Dhabi and in Saudi Arabia. For this reason, radiological safety is becoming a prime concern in the region. This review compiles published data on radionuclide concentrations in seawater, sediment, and biota that have been analyzed in the Gulf countries, along with spatial distribution patterns to enable a synoptic view of the available datasets. The seawater concentrations of ³H, ²¹⁰Po, ²¹⁰Pb, ¹³⁷Cs, and ⁹⁰Sr varied between 130 and 146, 0.48-0.68, 0.75-0.89, 1.25-1.38, 0.57-0.78 mBq L^-1, respectively. The ²²⁶Ra concentration in seawater varied between 0.26 and 3.82 Bq L^-1. Extremely high ⁴⁰K concentrations between 132 and 149 Bq L^-1 have been reported from the Iranian coast compared to 8.9-9.3 Bq L^-1 from the western side of the Gulf. Concentrations of ⁴⁰K, total ²¹⁰Pb, ¹³⁷Cs, ⁹⁰Sr, ²²⁶Ra, ²²⁸Ra, ²³⁸U, ²³⁵U, ²³⁴U, ^239+240Pu, and ²³⁸Pu were determined in sediment and ranged between 353 and 445, 23.6-44.3, 1.0-3.1, 4.8-5.29, 17.3-20.5, 15-16.4, 28.7-31.4, 1.26-1.30, 29.7-30.0, 0.045-0.21 and 0.028-0.03 Bq kg^-1 dry weight, respectively. Significantly higher ¹³⁷Cs values have been reported from the Iranian coast compared to the western coast of the Gulf. Whole fish concentrations of ⁴⁰K, ²²⁶Ra, ²²⁴Ra, ²²⁸Ra, ¹³⁷Cs, ²¹⁰Po and ⁹⁰Sr ranged between 230 and 447, 0.7-7.3, <0.5-6.6, <0.5-15.80, <0.17, 0.88-4.26 and 1.86-5.34 Bq kg^-1 dry weight, respectively. ²¹⁰Po was found to be highly concentrated in several marine organisms with the highest ²¹⁰Po concentration found in the clam Marcia marmorata (193.5-215.6 Bq kg^-1 dry weight). The review highlights the overall paucity of data and inconsistencies in the measurement of radionuclides throughout the Gulf region. Further, since the region is moving toward nuclear energy to meet its increasing energy demand, and coupled with the environmental effects from offshore oil exploration and the heavy impact of climate change, there is a pressing need to undertake a comprehensive marine radioactivity monitoring and assessment effort by conducting a joint cruise in the Gulf with participation of all the adjoining countries. Several recommendations on sampling marine matrixes in the Gulf are given with the aim of improving comparability of radionuclide data from the various studies undertaken in the Gulf region.

Assessment of the annual committed effective dose due to the 210Po ingestion from selected sea-food species in Vietnam

Activity concentration of ²¹⁰Po in the edible muscle tissues of twelve sea-food species (the most common marine food consumed of population in Vietnam) were analyzed using the PIPS detectors ORTEC Alpha-Ensemble spectrometer. The ²¹⁰Po activity concentration in studied samples was found to vary from 0.82 ± 0.47 to 70.3 ± 8.5 Bq/kg fresh weight. The highest activity concentration was recorded for the Blood cockle (Anadara granosa) and the lowest for Silver pomfret (Pampus argenteus). The annual committed effective dose (CED) of ²¹⁰Po to humans (the local residents) due to ingestion of each studied species was calculated from 18.5 to 1586 μSv/y. The average annual committed effective dose value was reported 394 μSv/y, which is marginally higher than the average CED contributed from ingestion of food and water total in global background (290 μSv/y).

The fate of the main naturally occurring radionuclides in mussels (Mytilus edulis) and their radiological impact on human beings

A comprehensive study was made on the activity concentrations, concentration factors, and radiation exposure impact of the main naturally occurring radionuclides in blue mussels collected in the Mediterranean Sea. The results showed that the concentrations of the measured radionuclides were site-specific and all detectable in gram-size samples of the soft tissues of the mussels, especially, some activity concentrations can reach as high as 16.8-102 Bq kg^-1 for ²¹⁰Po, 16.7-66.8 Bq kg^-1 for ⁴⁰K and 0.602-3.21 Bq kg^-1 for ²¹⁰Pb. The obtained mean concentration factors in the soft tissues of the mussel samples are 6.30 ± 2.40 for ²³⁸U and ²³⁴U, 4.68 ± 1.73 for ²³⁵U, (2.72 ± 1.73) × 10⁴ for ²³²Th and ²³⁰Th, 480 ± 265 for ²²⁸Th, 33.3 ± 13.3 for ²²⁶Ra, 100 ± 52 for ²²⁴Ra and 29.0 ± 14.7 for ²²⁸Ra, (1.22 ± 0.72) × 10⁴ for ²¹⁰Po, 517 ± 280 for ²¹⁰Pb and 2.57 ± 0.80 for ⁴⁰K. The estimated mean committed effective doses of ²³⁸U, ²³⁴U, ²³⁵U, ²³²Th, ²³⁰Th, ²²⁸Th, ²²⁶Ra, ²²⁴Ra, ²²⁸Ra, ²¹⁰Po, ²¹⁰Pb and ⁴⁰K to an adult due to mussel ingestion are 0.073 ± 0.027, 0.089 ± 0.035, 0.0030 ± 0.0011, 0.128 ± 0.098, 0.117 ± 0.081, 0.056 ± 0.031, 0.145 ± 0.058, 0.0487 ± 0.0250, 0.395 ± 0.200, 352 ± 209, 6.00 ± 3.25 and 1.74 ± 0.54 μSv a^-1, respectively. Among the elements or nuclides, ²¹⁰Po is the dominant dose contributor which contributes 96.9% of total dose fraction, and the relative dose contribution is in the order of ²¹⁰Po > ²¹⁰Pb > ⁴⁰K > radium ≥ thorium ≥ uranium.

Spatial variability in Polonium-210 and Lead-210 activity concentration in New Zealand shellfish and dose assessment

The activity concentrations of Polonium-210 (²¹⁰Po) and Lead-210 (²¹⁰Pb) were determined in shellfish (Perna canaliculus and Paphies subtriangulata) sampled bimonthly from March 2018 to February 2019 from 14 sites around New Zealand. Activity concentrations of ²¹⁰Po ranged from 4.7 ± 1.1 to 324 ± 17 Bq. kg^-1 with a mean value of 57 ± 72 Bq. kg^-1 (wet weight). The activity concentrations of ²¹⁰Pb were lower than those for ²¹⁰Po (0.1 ± 0.4 and 1.9 ± 0.4 Bq. kg^-1, with a mean value of 0.7 ± 0.4 Bq. kg^-1, wet weight). The calculated ²¹⁰Po/²¹⁰Pb activity concentration ratios were higher than unity in all samples indicating that radionuclides are not in equilibrium in shellfish and most of the ²¹⁰Po was unsupported by its grandparent ²¹⁰Pb. No significant difference was noted in ²¹⁰Po activity concentration between different seasons, species or shellfish condition index. Significant spatial variability in ²¹⁰Po activity concentration was observed with elevated ²¹⁰Po activity concentration in two sampling sites: Ninety Mile Beach (mean 257 ± 47 Bq. kg^-1) and Maunganui Bluff (mean 127 ± 22 Bq. kg^-1). Elevated ²¹⁰Po is hypothesised to be related to an increase of ²¹⁰Po accumulation through diet. Individuals who consume large quantities of shellfish (10 g per day or more) from areas affected by elevated ²¹⁰Po activity concentration may be exposed to an annual committed effective dose from ²¹⁰Po in shellfish in excess of 1 mSv.

A REVIEW ON 210Po AND 210Pb IN INDIAN SEAFOOD AND DOSE TO CONSUMERS

India is the second largest seafood producer in the world marketing more than 7000 edible species. In this regard, commendable studies have been conducted since the 1970s by different research groups and more data are reported. In this work, all the studies on 210Po and 210Pb measurements in abiotic and biotic components of India have been combined and reviewed. The concentrations of 210Po and 210Pb are estimated by radiochemical separation followed by alpha counting. Grain size, season, Tsunami waves and place of sampling have a decisive bearing on 210Po and 210Pb concentration in abiotic components. Plankton shows a higher Kd factor (104) compared to seaweeds and sea grass (103). Pond ecosystems recorded the highest Kd factor (4·3 × 104) compared to other freshwater and marine ecosystems. Bioaccumulation of 210Po and 210Pb varies with respect to variety of seafood. The committed effective dose (CED) calculated for shellfish species maintained a higher range of 2.5 × 10-2 mSv/y to 9.8 × 10-1 mSv/y and for fish species fluctuated from 3.8 × 10-4 mSv/y to 2.0 × 10-1 mSv/y. The studies conducted so far are scattered, and need to be gathered for future reference and planning (i.e. There is not much information available for Kerala, Karnataka, Maharashtra, Gujarat, Andhra, West Bengal and Odessa coast). Therefore, it is strongly recommended that further and more complete research is undertaken to study the bioaccumulation of 210Po and 210Pb from seafood. Overall, the present review concludes that Indian seafood is radiologically safe.

Mercury and Po-210 in mollusc species in the island of Gökçeada in the north-eastern Aegean Sea: Bioaccumulation and risk assessment for human consumers

Among the radioactive pollutants ²¹⁰Po is the most substantial one in terms of seafood safety due to its efficient accumulation in marine animals and high irradiation of its alpha emission. Mercury is a highly toxic metal for both marine organisms and human beings. Biomagnification of MeHg (methylmercury) through marine food chains has made Hg concern of ecotoxicology and seafood safety. In the current study, the bioaccumulation of ²¹⁰Po and THg (total mercury) were determined in 20 mollusc species, including 8 bivalves, 7 gastropods and 5 cephalopods collected from the island of Gökçeada in the north-eastern Aegean Sea. The highest accumulation of ²¹⁰Po and Hg was seen in bivalves and cephalopods, respectively. Elevated Hg concentrations in all body parts (arms, mantle and viscera) were observed in octopus' species. The results of this study suggests that filter feeder bivalves and gastropods have a capacity to concentrate ²¹⁰Po in their bodies, whereas predator gastropods and cephalopods have a capacity to concentrate Hg in their bodies. 7.0 kg (3.2-14.2) bivalve flesh intake is adequate due to ²¹⁰Po ingestion in the studied region to reach 1 mSv which is the annual committed effective dose. Octopus consumption of 705 g in a week alone is needed to reach Provisional Tolerable Weekly Intake (PTWI) of mercury, 5 μg kg^-1 body weight. Due to very low non-fish seafood consumption in Turkey there is no risk of Hg intake and alpha radiation of ²¹⁰Po above the limit values through mollusc consumption.

Enrichment effect of Hypnum plumaeforme on 210Po and 210Pb

The mosses have been widely used as bioindicators to investigate pollution and changes of heavy metals in different countries and regions. In this research, the field surveys were carried out for understanding the moss community and enrichment effects of the dominant species of mosses around the uranium mill tailings impoundment in South China, especially for the enriched contentions of ²¹⁰Pb and ²¹⁰Po in soil and Hypnum plumaeforme. The results showed that the maximum concentrations of U and ²²⁶Ra in the study sites were 93 mg kg^-1 and 1130.8 Bq kg^-1, respectively. The exhalation rate of ²²²Rn (ER_Rn), soil U, and ²²⁶Ra contents in SS₁, SS₂, and SS₃ were higher than CKS. With the increase of the distance from the central well, the contents of nuclides (U and ²²⁶Ra) in soils and H. plumaeforme were both decreased. And, the bioconcentration factors of H. plumaeforme for ²¹⁰Pb and ²¹⁰Po ranged from 1.05 to 1.49, and 1.25 to 1.40, respectively, indicating an accumulation of ²¹⁰Po and ²¹⁰Pb from soil by H. plumaeforme. These results indicated that H. plumaeforme is hopeful to become an accumulator plant for remediation of radon pollution, and also can be used as a potential indicator plant for radon pollution monitoring.

Concentration of 210Po and 210Pb in macroalgae from the northern Gulf

This baseline study highlights the 210Po and 210Pb concentration in seven macroalgae species from the northern Gulf that are frequently washed ashore during the bloom season from February to April. The highest concentrations of 210Po and 210Pb were 2.947 ± 0.032 and 1.057 ± 0.145 Bq kg-1 wwt, respectively, in brown algae Sargassum boveanum, and the lowest in green algae Ulva prolifera with 1.533 ± 0.058 and 0.170 ± 0.069 Bq kg-1 wwt, respectively. A 210Po enrichment was observed in both brown and green algae species, with the 210Po/210Pb ratio being >1 for all the samples. The mean concentration of 210Po in all species was an order of magnitude higher than 210Pb, and the difference in mean concentration is statistically significant (p < 0.001). At the same time, the mean concentration of dissolved 210Po and 210Pb in seawater was 0.28 ± 0.01 and 0.52 ± 0.01Bq m-3 with a 210Po/210Pb ratio of 0.54 ± 0.02 indicating that 210Po was absorbed from water and more concentrated by macroalgae. The measured concentration factor (CF) for 210Po in these macroalgae for the northern Gulf varied between 5 × 103-1 × 104, higher than the IAEA recommended value of 1 × 103 which suggests that a revision of that value may be needed. The field derived CFs for 210Pb vary between 3 × 102-1.8 × 103, comparable to the ICRP recommended value of 2 × 103.

Geographical origin of bivalve molluscs in coastal areas using natural radioactivity fingerprinting and multivariate statistical analyses: Andalusian coast as case of study

The presence of natural and artificial radionuclides in the marine environment produces the accumulation of radionuclides in bivalve molluscs consumed by humans, and therefore it could result in a radiological hazard. In this study, the activity concentrations of ²¹⁰Po, ⁴⁰K, ²¹⁰Pb and ²³⁴Th were determined in different types of bivalve molluscs sampled during the period of May 2014-June 2015, along coastal areas from the Andalusian region (South of Spain), through alpha-particle spectrometry and low-level gamma-ray spectrometry. The activity concentrations of ²¹⁰Po; ⁴⁰K; ²¹⁰Pb and ²³⁴Th varied between 40 ± 2 and 515 ± 9 Bq kg^-1 dry weight (d.w.); 121 ± 7 and 674 ± 34 Bq kg^-1 d.w.; ND (lower than limit of detection) and 73 ± 10 Bq kg^-1 d.w.; and ND and 126 ± 27 Bq kg^-1 d.w., respectively. The committed effective dose to humans was calculated to range from 41 to 479 μSv year^-1. Both activity concentrations and dose levels were comparable to previous studies from other countries. Finally, a multivariate statistical analysis of natural radioactivity content allowed the discrimination between bivalve molluscs from Atlantic and Mediterranean coasts.

Assessment of the committed effective dose due to the 210Po intake from fish consumption for the Arabian Gulf population

This study aims to assess the committed effective dose due to the intake of ²¹⁰Po from the consumption of fish in Arabian Gulf countries. Twenty different kinds of fish, which represent the most common fish species consumed in the Arabian Gulf countries, were analyzed using alpha spectrometer technique. ²¹⁰Po activity concentrations in fish samples were found to vary over a wide range from 0.1 to 14.7 Bq kg^-1 fresh weight. This variation of ²¹⁰Po concentrations between various type of fish samples might be attributed to the feeding type pattern and the size of fish. The annual committed effective dose due to ingestion of ²¹⁰Po in fish species for adults in the Arabian Gulf countries was estimated and found to vary from 38 μSv in Bahrain to 85 μSv in Oman with an average value of 59 μSv. These values are considered relatively high compared to those reported in some other regions. However, it is still much lower than the world average ingestion dose due to natural radiation sources.

An investigation on the seasonal variations of the biomarkers of oxidative stress response and their correlations to Polonium-210 in mussel (Mytilus galloprovincialis) and common sole (Solea solea) from İzmir Bay, Turkey

It is well known that the marine organisms are used as biological indicators for environmental pollution studies. Among these studies, the research on oxidative stress has been increasing in recent years. In this study, mussels (Mytilus galloprovincialis) and fish (Solea solea) samples were collected seasonally from İnciraltı, İzmir, Turkey. This station was in an area where fishing is carried out for human consumption. The relationship between ²¹⁰Po and oxidative stress markers (lipid peroxidation (LPO), H₂O₂ and proline) was investigated in the mussel tissue (digestive gland, gills) and fish tissue (liver, gills) samples. The present study indicated that H₂O₂ accumulated with increasing ²¹⁰Po concentration in mussel samples. Statistically significant correlation were found between H₂O₂ and ²¹⁰Po and LPO and proline in mussel samples. This correlation between LPO and proline can be attributed to common environmental parameters (other than ²¹⁰Po) affecting expression of both LPO and proline levels. There was not a significant correlation between ²¹⁰Po and LPO levels. Similarly, a significant correlation was not found between ²¹⁰Po and proline.

Baseline activity concentration of 210Po and 210Pb and dose assessment in bivalve molluscs at the Andalusian coast

In this study, the activity concentrations of ²¹⁰Po and ²¹⁰Pb were determined in different types of bivalve molluscs sampled during the period of May 2014-June 2015 along the Andalusian littoral. Radioactivity concentrations of ²¹⁰Po were determined through alpha-particle spectrometry using ²⁰⁹Po as an internal tracer. Radioactivity concentrations of ²¹⁰Pb were determined through low-level gamma-ray spectrometry. The activity concentrations of ²¹⁰Po and ²¹⁰Pb varied between 40 ± 2 and 515 ± 9 Bq kg^-1 dry weight (d.w.), and ND (lower than limit of detection) and 73 ± 10 Bq kg^-1 d.w., respectively. The committed effective dose to humans was calculated to range from 39 to 477 μSv year^-1. Radioactivity and dose levels were compared with previous studies from other countries.

210Po in the marine biota of Korean coastal waters and the effective dose from seafood consumption

The activity concentrations of ²¹⁰Po were determined in plankton and selected species of macroalgae, crustaceans, molluscs, and fish from Korean coastal waters to understand ²¹⁰Po distribution in these trophic levels and to assess the effective dose of ²¹⁰Po from seafood ingested by the average Korean. The activity concentration of ²¹⁰Po in macroalgae, mixed plankton, anchovy (whole body), abalone muscle, and abalone viscera was 0.97-1.43, 32-137, 59-392, 2.93 ± 0.86, and 1495 ± 484 Bq kg^-1 (w.w.), respectively. Polonium-210 concentration in the whole flesh of mussel and oyster were 47.8 ± 5.9 and 45.3 ± 7.1 Bq kg^-1 (w.w.), respectively. Polonium-210 concentration in the muscle of the five tested species of fish other than anchovy ranged from 0.51 to 5.56 Bq kg^-1 (w.w.), with the lowest amount in a demersal species. In fish, ²¹⁰Po activity concentration was as much as three orders of magnitude higher in viscera than in muscle. The average annual effective ²¹⁰Po dose per average Korean adult, who consumes 42.8 kg of seafood a year (excluding anchovy), was estimated to be 94 μSv y^-1, with 42-71% of this attributed to shellfish. Further studies are required to assess the dose of ²¹⁰Po from anchovy owing to its high activity concentration and the manner in which anchovy is consumed.

Occurrence of 210Po in marine macroalgae inhabiting a coastal nuclear zone, southeast coast of India

The activity concentration of ²¹⁰Po in 26 species of marine macroalgae found along coast near to a nuclear installation in southeast coast of India was studied. Phaeophytes were found to accumulate the maximum ²¹⁰Po concentration and chlorophytes the minimum. The average ²¹⁰Po activity concentration values in the three groups were 6.2 ± 2.5 Bq kg^-1 (Chlorophyta), 14.4 ± 5.2 Bq kg^-1 (Phaeophyta) and 11.3 ± 3.9 Bq kg^-1 (Rhodophyta). A statistically significant variation in accumulation was found between groups (p < 0.05). The un-weighted dose rate to these algae due to ²¹⁰Po was calculated to be well below the benchmark dose limit of 10 μGy h^-1.

Bioaccumulation of natural radionuclides in molluscs from the Ebro Delta area

²¹⁰Po, ²¹⁰Pb, ²³⁴U, ²³⁸U, ²³²Th and ²³⁰Th were analysed in the edible part of four different species of bivalves typically produced and consumed in the Ebro Delta area. The results show that the main contributor to the radioactive content in these species was ²¹⁰Po, with values ranging between 263.1 ± 26.6 and 813.0 ± 72.9 Bq/kg (d.w.), which are higher than the usual reported activity levels in other geographical areas. This can probably be attributed to the activities of a phosphate industrial plant located upstream on the Ebro River, which may lead to enhanced levels of naturally occurring radioactive isotopes in the aquatic ecosystem. To determine the possible impact on health, the committed effective doses through the consumption of the different species were evaluated and the cumulative total annual effective dose for their consumption was estimated to 187.6 μSv/year, which is in the range of 200-1000 μSv/year given by UNSCEAR.

Baseline concentration of Polonium-210 ((210)Po) in tuna fish

Several species of tuna fish were analyzed for (210)Po content in their edible muscle tissues. This study was carried out as a part of baseline data generation around a large nuclear power plant situated at Kudankulam, southeast coast of India. The concentration of (210)Po in the muscle tissue ranged from 40.9±5.2 to 92.5±7.9Bq/kg of fresh fish, and the highest activity was recorded for the tuna Euthynnus affinis and the lowest for Auxis thazard. The committed effective dose to the local residents was calculated to be 62.7-141.8μSvyear(-1).

Influence of submarine groundwater discharge on (210)Po and (210)Pb bioaccumulation in fish tissues

This study presents the results of the accumulation of (210)Po and (210)Pb in fish tissues and organs in a brackish-water marshland that is characterized by high concentrations of (222)Rn and (226)Ra supplied by submarine groundwater discharge (SGD). Tissues and organs from Cyprinus carpio, Chelon labrosus and Carassius auratus in the wetland were significantly enriched by both (210)Pb and (210)Po (up to 55 and 66 times, respectively) compared to blanks. The major input route of (210)Pb and (210)Po into the fish body seems to be through ingestion, due to the high levels of (210)Pb and (210)Po found in the gut content as well as in organs involved in digestion and metabolism (i.e. gut, kidney and hepatopancreas). Results showed that (210)Po was more accumulated in all fish tissues and organs except for the spine, which showed a higher affinity for (210)Pb, due to its capacity to replace Ca from apatite in bones. Over all the variables analyzed, fish tissues/organs and, secondarily, fish species were the most important factors explaining the concentration of radionuclides, whereas fish length and the sampling location played a minor role. The relationship of the two radionuclides varied markedly among tissues and their concentration levels were only correlated in gills, gut and, marginally, in spines. In general, the highest values of (210)Pb and (210)Po concentrations in tissues were found on C. labrosus tissues rather C. auratus and C. carpio. This study demonstrates that inputs of natural radionuclides supplied by SGD to coastal semi-enclosed areas (such as marshlands, lagoons or ponds) may significantly increase the contents of (210)Pb and (210)Po in fish tissues/organs. Thus, this study represents one of the first evidences of direct ecological effects derived from SGD.

Radioactivity in the Kuwait marine environment--Baseline measurements and review

The Arabian Gulf region is moving towards a nuclear energy option with the first nuclear power plant now operational in Bushehr, Iran, and others soon to be constructed in Abu Dhabi and Saudi Arabia. Radiological safety is becoming a prime concern in the region. This study compiles available data and presents recent radionuclide data for the northern Gulf waters, considered as pre-nuclear which will be a valuable dataset for future monitoring work in this region. Radionuclide monitoring in the marine environment is a matter of prime concern for Kuwait, and an assessment of the potential impact of radionuclides requires the establishment and regular updating of baseline levels of artificial and natural radionuclides in various environmental compartments. Here we present baseline measurements for (210)Po, (210)Pb, (137)Cs, (90)Sr, and (3)H in Kuwait waters. The seawater concentration of (3)H, (210)Po, (210)Pb, (137)Cs, and (90)Sr vary between 130-146, 0.48-0.68, 0.75-0.89, 1.25-1.38 and 0.57-0.78 mBq L(-1), respectively. The (40)K concentration in seawater varies between 8.9-9.3 Bq L(-1). The concentration of (40)K, total (210)Pb, (137)Cs, (90)Sr, (226)Ra, (228)Ra, (238)U, (235)U, (234)U, (239+240)Pu and (238)Pu were determined in sediments and range, respectively, between 353-445, 23.6-44.3, 1.0-3.1, 4.8-5.29, 17.3-20.5, 15-16.4, 28.7-31.4, 1.26-1.30, 29.7-30.0, 0.045-0.21 and 0.028-0.03 Bq kg(-1) dry weight. Since, radionuclides are concentrated in marine biota, a large number of marine biota samples covering several trophic levels, from microalgae to sharks, were analyzed. The whole fish concentration of (40)K, (226)Ra, (224)Ra, (228)Ra, (137)Cs, (210)Po and (90)Sr range between 230-447, 0.7-7.3, <0.5-6.6, <0.5-15.80, <0.17, 0.88-4.26 and 1.86-5.34 Bq kg(-1) dry weight, respectively. (210)Po was found to be highly concentrated in several marine organisms with the highest (210)Po concentration found in Marica marmorata (193.5-215.6 Bq kg(-1) dry weight). (210)Po in most dissected fish samples shows increasing concentrations in the following order: edible tissue, gills, digestive system, liver and fecal matter. Fish fecal pellets had (210)Po concentrations several orders of magnitude higher than the seawater, fish muscle, and the fishes' ingested food. The high (210)Po concentration in fish fecal matter, suggest that the bulk of (210)Po content in fish was eventually excreted back into the environment as fecal pellets. In most fish high concentrations were noted in liver, with the highest (210)Po concentration recorded in shark liver (126.2-141.5 Bq kg(-1) wet). Moreover, (210)Po concentration in the soft tissue of molluscs (10.36-215.60 Bq kg(-1) dry weight) was far higher than that in fish muscle (0.05-7.49 Bq kg(-1) wet weight). A seasonal drop in (210)Po concentration in seawater was observed to vary with the abundance of phytoplankton and macroalgae due possibly to biological dilution. (137)Cs concentration in all the fish sampled was below the detection limit, and the concentration in seawater was also low; hence such low levels provide an opportunity to use this radionuclide as an indicator for any future radiocesium releases in this region.

The English Channel: Contamination status of its transitional and coastal waters

The chemical contamination (organic compounds, metals, radionuclides, microplastics, nutrients) of English Channel waters has been reviewed, focussing on the sources, concentrations and impacts. River loads were only reliable for Pb, whereas atmospheric loads appeared robust for Cd, Pb, Hg, PCB-153 and γ-HCH. Temporal trends in atmospheric inputs were decreasing. Contaminant concentrations in biota were relatively constant or decreasing, but not for Cd, Hg and HBCDD, and deleterious impacts on fish and copepods were reported. However, data on ecotoxicological effects were generally sparse for legacy and emerging contaminants. Intercomparison of activity concentrations of artificial radionuclides in sediments and biota on both Channel coasts was hindered by differences in methodological approaches. Riverine phosphate loads decreased with time, while nitrate loads remained uniform. Increased biomass of algae, attributable to terrestrial inputs of nutrients, has affected benthic production and shellfisheries. A strategic approach to the identification of contaminant impacts on marine biota is recommended.

Assessment of Radiation and Heavy Metals Risk due to the Dietary Intake of Marine Fishes (Rastrelliger kanagurta) from the Straits of Malacca

The environment of the Straits of Malacca receives pollution as a result of various industrial and anthropogenic sources, making systematic studies crucial in determining the prevailing water quality. Present study concerns concentrations of natural radionuclides and heavy metals in marine fish (Rastrelliger kanagurta) collected from the Straits of Malacca, since aquatic stock form an important source of the daily diet of the surrounding populace. Assessment was made of the concentrations of key indicator radionuclides (226Ra, 232Th, 40K) and heavy metals (As, Mn, Fe, Cr, Ni, Zn, Cu, Co, Sr, Al, Hg and Pb) together with various radiation indices linked to the consumption of seafish. The annual effective dose for all detected radionuclides for all study locations has been found to be within UNSCEAR acceptable limits as has the associated life-time cancer risk. The overall contamination of the sampled fish from heavy metals was also found to be within limits of tolerance.

Assessment of committed effective dose due to the ingestion of (210)Po and (210)Pb in consumed Lebanese fish affected by a phosphate fertilizer plant

Ingestion of radionuclides through seafood intake is a one of the sources contributing to the internal effective dose in the human organism. In order to evaluate the internal exposure and potential risks due to (210)Po and (210)Pb associated with fish consumption, these radionuclides were measured in commonly consumed fish species from a clean area and an area subjected to the impact of a Lebanese phosphate fertilizer plant. The highest concentration of (210)Pb was 98.7 Bq/kg fresh weight while (210)Po activity concentrations varied from 3.6 Bq/kg to 140 Bq/kg. A supplementary radiation exposure was detected; the highest committed effective dose due to (210)Po and (210)Pb was found to be 1110 μSv/y and 450 μSv/y, respectively. Moreover, the average mortality and morbidity risks due to the fish consuming were estimated.

Baseline concentration of ²¹⁰Po and ²¹⁰Pb in Sargassum from the northern Gulf

This baseline study highlights the (210)Po and (210)Pb concentration in two species of the benthic macroalgae Sargassum from northern Gulf, also known as the ROPME Sea Area (RSA). Within the marine environment, (210)Po is initially absorbed from water and concentrated by phytoplankton and macroalgae, and this concentrated (210)Po can then readily be passed along to the higher trophic level of the marine food web. The (210)Po concentration measured in Sargassum boveanum (22.5-25.6 Bq kg(-1)) was higher than that in Sargassum oligocystum (20.2-22.5 Bq kg(-1)), but is not statistically significant (p>0.064), where as the difference between (210)Pb concentrations in Sargassum boveanum (15.3-16.8 Bq kg(-1)) and Sargassum oligocystum (18.4-22.0 Bq kg(-1)) was statistically significant (p>0.019). The measured concentration factor for (210)Po in Sargassum in the northern Gulf varied between 0.55 and 1.2×10(4), values higher to the IAEA recommended value of 1×10(3). The (210)Po enrichment is observed in both the species of Sargassum,(210)Po/(210)Pb ratio was >1 at all the stations for all the samples.

Polonium-210 and selenium in tissues and tissue extracts of the mussel Mytilus galloprovincialis (Gulf of Trieste)

Marine organisms such as mussels and fish take up polonium (Po) and selenium (Se), and distribute them into different cellular components and compartments. Due to its high radiotoxicity and possible biomagnification across the marine food chain Po-210 is potentially hazardous, while selenium is an essential trace element for humans and animals. The aim of this study was to investigate and compare the presence and extractability of the elements in the mussels Mytilus galloprovincialis collected in the Gulf of Trieste. The levels of Po-210 in the samples ranged from 220 to 400 Bq kg(-1) and of Se from 2.6 to 8.2 mg kg(-1), both on a dry matter basis. Using various extraction types and conditions in water, buffer or enzymatic media, the best extractability was obtained with enzymatic extraction (Protease XIV, 1h shaking at 40 °C) and the worst by water extraction (24 h shaking at 37 °C). 90% of Po-210 and 70% of Se was extractable in the first case versus less than 10% of Po-210 and less than 40% of Se in the second. Such evident differences in extractability between the investigated elements point to different metabolic pathways of the two elements. In enzymatic extracts Se speciation revealed three Se compounds (SeCys2, SeMet, one undefined), while Po-210 levels were too low to allow any conclusions about speciation.

Polonium-210 in marine mussels (bivalve molluscs) inhabiting the southern coast of India

The present study focused on the determination of the alpha-emitter, (210)Po, in two species of marine mussels (bivalve molluscs) commonly available in the southern coastal region of India. The brown mussel, Perna indica was collected from the west coast and the green mussel, Perna viridis from the east coast. The concentration of (210)Po was related to the allometry (length of shell, wet/dry weight of shell/soft tissue) of the mussels and significant results were found. The study period focused on three seasons namely, pre-monsoon, monsoon and post-monsoon for a 1-year period (2010-2011). The results revealed higher activity levels in smaller-sized mussels compared to larger ones. Marked variation in (210)Po activity concentration was noted in the whole-body soft tissues between seasons and sampling site (p < 0.05). The dose rate assessment for mussels was performed using the ERICA Assessment tool. The chronic exposure to mussels due to (210)Po was found to be lesser than the global benchmark dose rate of 10 μGy h(-1). The effective ingestion dose to adults who intake mussels was estimated to be in the range 5.1-34.9 μSv y(-1). The measurement contributes to the furthering of knowledge of (210)Po, since no data exist in this region.

Investigation of the radiological impact on the coastal environment surrounding a fertilizer plant

This investigation was carried out in order to assess the marine environmental radioactive pollution and the radiological impact caused by a large production plant of phosphate fertilizer, located in the Lebanese coastal zone. Natural radionuclides ((238)U, (235)U, (232)Th, (226)Ra, (210)Po, (210)Pb, (40)K) and anthropogenic (137)Cs were measured by alpha and gamma spectrometry in seawater, sediment, biota and coastal soil samples collected from the area impacted by this industry. The limited environmental monitoring program within 2 km of the plant indicates localized contamination with radionuclides of the uranium decay chain mainly due to the transport, the storage of raw materials and the free release of phosphogypsum waste.

Seasonal and spatial variations of 210Po and 210Pb activity concentrations in Mytilus galloprovincialis from Croatian coast of the Adriatic Sea

Results of 2 years monitoring of (210)Po and (210)Pb activity concentrations in soft tissue of the species Mytilus galloprovincialis from Croatian part of the Adriatic coast are presented. The samples were collected at thirteen coastal stations (some of which are also a part of the Mediterranean Mussel Watch Project) in spring and autumn of 2010 and 2011. The collected mussels were ranging between 4 cm and 6 cm in shell length. After sample pre-treatment lead and polonium were radiochemically separated on Sr resin. (210)Po was determined by alpha-particle spectrometry and (210)Pb was determined, via (210)Bi, by a low-level gas proportional counter. The results of (210)Po activity concentrations were found to vary between (104±11) and (1421±81) Bq kg(-1) dry weight while (210)Pb activity concentrations were much lower and in range (8.2±5.3)-(94.1±29.8) Bq kg(-1) dry weight. Higher (210)Po and (210)Pb activity concentrations were determined in spring period. The inter-site differences seen in their activity concentrations can be due to natural background levels of sites. The (210)Po/(210)Pb activity concentration ratios in all cases exceeded unity for all mussel samples and ranged between 4.0 and 47.9.

Occurrence of 210Po in periwinkle (Littorina undulata, Gray, 1839) collected from Kudankulam (Gulf of Mannar (GOM), Southeast coast of India)

Polonium-210 activity concentration was analysed in the whole body tissue of periwinkle Littorina undulata collected from intertidal rocky shore along Kudankulam coast. We carried out the study for a period of 12 months (2011-2012) focusing on three seasons. (210)Po was found non-uniformly distributed among the periwinkles depending on the allometry. The (210)Po accumulation showed a significant difference between seasons (p<0.05). Smaller sized winkles registered higher activity of (210)Po compared to larger ones (p<0.05). The overall activity range of (210)Po varied from 13.5 to 58.9 Bq/kg (wet). The activity of (210)Po was also quantified in seawater and intertidal sediments to calculate the biological concentration factor (BCF) and radiation dose rate. The dose rate to the winkles was performed using ERICA Assessment Tool and it was within the prescribed limit. The intake of (210)Po through periwinkles delivered an effective dose in the range of 2.2-9.6 μSv/y to human beings.

Levels of (210)Po in some commercial fish species consumed in the Aegean Sea coast of Turkey and the related dose assessment to the coastal population

Concentrations of (210)Po were determined in the edible muscle tissue of five species of marine fish: Sardine (Sardine plichardus) and Anchovy (Engraulis encrasicolus), Red mullet (Mullus barbatus), Horse mackerel (Trachurus trachurus) and Gilt-head sea bream (Sparus aurata) collected from five stations in the Aegean Sea Region of Turkey during the fishery season 2010. The (210)Po concentrations in the fish samples were found to vary from not detected levels to 389 ± 45 Bq kg(-1) dry wt. These variations in (210)Po content in different species are probably due to differences in metabolism and feeding patterns. The highest levels for (210)Po were observed in Anchovy (E. encrasicolus) species.