The research team set out to study undisturbed soils, meaning soils unaffected by industrial activity, collected from areas in close proximity to industrial sites. The logic is elegant: by sampling near but not within anthropogenically affected zones, the investigators could assess whether human activity had spilled radionuclides into the surrounding environment. Four expeditions covered the liquidated Madzharovo lead-zinc mines, the Ada Tepe gold mine, the Kardzhali mining complex, the Neochim fertilizer plant, gneiss extraction sites and marble quarries. At each representative point, five samples were collected according to the Bulgarian standard BSS 17.4.5.01:1985, following ISO 18589-2,3 (2007) protocols. Surface layers from 0 to 5 centimeters were taken to monitor contamination, while samples down to 20 centimeters characterized the process in depth.

Preparation followed a rigorous pipeline. Soil samples were air-dried, homogenized, ground and sieved through a 2-millimeter mesh before being packed into 0.5-liter Marinelli containers with 4π geometry, a configuration that surrounds the detector and maximizes counting sensitivity. The analytical heart of the study was gamma spectrometry with a CANBERRA DSA 1000 multichannel analyzer coupled to an ultra-pure germanium detector with 35 percent efficiency and 1.8 keV resolution. This setup allows simultaneous and direct measurement of numerous gamma emitters across energies from 50 to 2000 keV. To achieve statistical reliability, each sample was measured for 19 to 24 hours, an unusually long acquisition time that tightens the uncertainty on every reported value.

The technique exploits the fact that each radionuclide emits gamma rays at characteristic energies. Uranium-238 was quantified through its daughter product thorium-234, detected at 63.3 keV and 92.3 keV. Radium-226 was determined from the peak at 186.3 keV, with careful correction for the overlapping uranium-235 line at 185.6 keV. Lead-210 was measured by its gamma line at 46.6 keV, thorium-232 through its daughter actinium-228 at 911.0 keV, and potassium-40 by the full energy peak at 1461 keV. The technogenic isotope cesium-137, the fingerprint of nuclear tests and the Chernobyl accident, was identified by its signature line at 661.6 keV. From these specific activities, expressed in becquerels per kilogram of dry soil, the team calculated two standard indicators of radiological risk.

The first is the radium equivalent activity, Ra_eq, computed as the sum of the radium-226 activity plus 1.43 times the thorium-232 activity plus 0.077 times the potassium-40 activity, following Beretka and Mathew’s 1985 formulation. The maximum permissible level is 370 Bq/kg. The second is the external hazard index, H_ex, defined by Krieger’s 1981 formula as the uranium-238 activity divided by 370, plus the thorium-232 activity divided by 259, plus the potassium-40 activity divided by 4810, with a limit of 1. Both indices assume uniform exposure to gamma radiation from the soil and are widely used to translate raw activity concentrations into a population-level hazard estimate.

The results span a wide but familiar range. Across the studied points, specific activities were: uranium-238 from 9 to 62 Bq/kg, radium-226 from 11 to 92 Bq/kg, thorium-232 from 16 to 82 Bq/kg, potassium-40 from 260 to 1432 Bq/kg, and lead-210 from 26 to 64 Bq/kg. Compared with the world averages reported by the United Nations Scientific Committee on the Effects of Atomic Radiation, roughly 35 Bq/kg for uranium-238 and radium-226, 30 Bq/kg for thorium-232 and 400 Bq/kg for potassium-40, the Eastern Rhodopes values sit within background amounts and are comparable to global averages. They also fall within the ranges cited for Bulgaria as a whole, which vary from 8 to 190 Bq/kg for uranium-238 and 40 to 800 Bq/kg for potassium-40.

Some of the highest potassium-40 values appeared near the Ada Tepe gold mine and the Madzharovo mine, where measured activities were twice the world average, reaching over 1400 Bq/kg. The explanation is geological rather than industrial: sedimentary rocks rich in organic remains, characteristic of the region’s past as a water basin with active underwater volcanism, concentrate potassium. The predominance of sedimentary rocks in the Eastern Rhodopes, especially those of biogenic origin with very low radioactive element content, also accounts for the differences observed between the Eastern and Western Rhodopes. The wide potassium-40 range is characteristic of the cinnamon forest soils predominant in the region, reflecting the great variety of soil-forming rocks.

One subtle geochemical signal emerged: a shift in the radioactive equilibrium between uranium-238 and radium-226, with higher radium content in some samples. This disequilibrium likely reflects the lower mobility of radium in soils, the low humus content, and the greater solubility of uranium salts, which allows uranium to migrate along the soil profile. Notably, no significant differences were found between arable and non-arable soils, and the measured radionuclide levels correspond to average or slightly above-average values typical for Bulgaria’s geographical latitude, within the values cited in the literature as normal for the respective regions.

The technogenic story is a Chernobyl echo. Cesium-137 entered the environment through nuclear tests in the 1960s and the 1986 accident, and southern Bulgaria was the most affected part of the country, with four to five times higher activity concentrations than the north. The isotope bound to the surface soil layer and persisted thanks to its long half-life. In the present study, 35 years after Chernobyl, cesium-137 ranged from less than 1 to 87 Bq/kg, confirming the strong spatial inhomogeneity documented previously, where values varied between 3 and 1700 Bq/kg even within tens of square meters. The decline in surface activity is mainly due to radioactive decay. For context, before 1986 the average in southern Bulgaria was 26 Bq/kg, and by 1996 averages varied between 160 and 280 Bq/kg there, with the highest regional values ever registered in the Western Rhodopes, up to 261 Bq/kg.

Crucially, the hazard indices stayed within safe limits. The external hazard index did not exceed the permissible upper bound of 1 at any sampling point, and the radium equivalent activity remained low relative to the 370 Bq/kg threshold. With both indicators below their limits, the study area of the Eastern Rhodopes is within normal background amounts and does not pose a radiation hazard for the population or the biota. No additional pollution or impact of industrial activities on radionuclide content was detected. Yet the authors caution that the region is one of the richest territories in biodiversity in Europe, home to many Balkan endemics and highly endangered species, close to Natura 2000 sites, and of growing interest for tourism. Because most industrial sites lie near surface water bodies, and migration of uranium, radium-226, lead-210 and thorium-232 through surface water is a major contamination pathway, the team recommends a radiological assessment of ground and surface water in the studied areas, particularly given the systematic use of unregulated drinking water sources in the region.

Subject of Research: Environmental radioactivity survey of soils in the Eastern Rhodopes, Bulgaria

Article Title: Radiation status of soils from the region of the Eastern Rhodopes (Southern Bulgaria)

Article References: Hristozova, M., & Lazarova, R. (2022). Radiation status of soils from the region of the Eastern Rhodopes (Southern Bulgaria). BioRisk, 17, 45-57. https://doi.org/10.3897/biorisk.17.77432

Image Credits: AI Generated

DOI: 10.3897/biorisk.17.77432

Keywords: Eastern Rhodopes, Bulgaria, gamma spectrometry, natural radionuclides, cesium-137, Chernobyl fallout, soil contamination, mining, radium equivalent activity, external hazard index, Radiation, status

A research team collected sand from 33 locations stretching along the entire 354-kilometre Bulgarian coastline, from the village of Durankulak near the Romanian border down to Rezovo at the Turkish frontier. Roughly 200 kilometres of this shore consists of sandy beaches, formed over millennia by the weathering and erosion of igneous and metamorphic rocks in the surrounding terrain. Because such sediments naturally carry traces of radioactive elements from the Earth’s crust, measuring them offers a direct window into the radiological environment that residents and tourists experience every day.

Each sample was cleaned and dried in a laboratory oven at temperatures up to 60 degrees Celsius, then sealed into cylindrical containers for gamma-spectrometric analysis. The measurements relied on a semiconductor detector with a 60-cubic-centimetre crystal, operating at 1 kilovolt with a relative efficiency of 4.5 percent for the caesium-137 gamma line. To keep ambient background radiation from contaminating the results, the detector was wrapped in layered shielding of lead, aluminium, cadmium and polyethylene, and the resulting spectra were processed with dedicated software that calculated each isotope’s specific activity from its characteristic gamma peaks.

The analysis identified the classic natural radioactive fingerprint of beach sands: isotopes from the uranium-radium and thorium decay series, detected through gamma lines of daughter products such as lead-214, bismuth-214, actinium-228 and thallium-208, plus the primordial isotope potassium-40, identified by its 1460.80-kiloelectronvolt gamma line. On average, the sands contained 11.62 becquerels per kilogram of uranium-238, 6.82 becquerels per kilogram of thorium-232 and 396.55 becquerels per kilogram of potassium-40. Every one of these figures falls below the global averages of 35, 30 and 370 becquerels per kilogram respectively, as compiled by the United Nations Scientific Committee on the Effects of Atomic Radiation.

The spread between individual beaches tells its own story. Uranium-238 activities ranged from 5.80 becquerels per kilogram at Rezovo Beach to 28.30 at Irakli Beach, while thorium-232 mostly stayed between 3 and 12 becquerels per kilogram, with Irakli again standing out at 19.06. Potassium-40, the most abundant of the three natural isotopes, varied from roughly 209 to 705 becquerels per kilogram, peaking at Rapongi Beach in Varna and dipping lowest near the village of Tyulenovo. Frequency analysis showed that 84 percent of uranium measurements clustered between 7 and 16 becquerels per kilogram, 87 percent of thorium values sat between 5 and 10, and 70.5 percent of potassium readings fell between 240 and 550.

One artificial isotope also made an appearance. Caesium-137, a fission product of atmospheric nuclear weapons tests and reactor accidents, was detected in 11 of the 33 samples at concentrations between 1.4 and 3.4 becquerels per kilogram, with the highest value at Kavarna Beach. That average of 3.16 becquerels per kilogram is modest by any measure, and consistent with recent regional surveys, which have recorded caesium-137 in Black Sea sands at anywhere from 0.8 to 12.3 becquerels per kilogram. Its presence is a faint echo of mid-twentieth-century fallout in a basin that has long been considered one of the more radioactively studied marine environments in the world.

Using the GPS coordinates of every sampling point, the team generated geostatistical distribution maps that reveal how radioactivity varies along the coast. Uranium-238 proved fairly uniform, with its maximum at Irakli. Thorium-232 showed its lowest values in the northern Black Sea, with a single pronounced hot spot at Irakli Beach. Potassium-40 peaked near Tyulenovo and the Rai campsite at Kamchiya, while caesium-137 reached its highest concentrations around Kranevo village and the central beach of Golden Sands, with levels gradually rising toward the southern stretch of the coast.

Beyond raw isotope counts, the researchers calculated a battery of internationally recognised radiation hazard indices, including radium equivalent activity, gamma index, external and internal hazard indexes, outdoor absorbed dose rate, annual effective dose, excess lifetime cancer risk and absorbed dose rate in air. The averages were unremarkable in the best sense: an absorbed dose rate in air of 26.32 nanogray per hour against a world average of 84, an annual effective dose of 0.16 millisieverts per year against a global benchmark of 0.48, and a radium equivalent activity of 51.90 becquerels per kilogram, far under the 370 limit. External and internal hazard indexes came in at 0.14 and 0.17, both well below the safety threshold of one, and the estimated excess lifetime cancer risk of 0.11 per thousand sat below the reference value of 0.29. The maps of these indices flagged mild hot spots at Tyulenovo, the Rai campsite and Primorsko’s southern beach, with the lowest readings at Rezovo.

The statistical treatment went further than simple averages. Pearson correlation analysis across twelve radiological variables showed that 83 percent of the coefficients fell into the high or very high correlation ranges, confirming that the calculated hazard indices move in lockstep with the underlying isotope concentrations. Notably, thorium-232 correlated only weakly with the radiological parameters, leading the authors to conclude that thorium and its decay products exert the least influence on the natural radioactivity of these beaches. A hierarchical cluster analysis reinforced this picture, grouping ten radiological factors together while potassium-40 stood apart in its own cluster, and linking uranium-238 and thorium-232 most closely to the overall radiological parameter levels.

For beachgoers, the practical takeaway is simple: the sands of the Bulgarian Black Sea coast deliver a radiation dose well within internationally published limits set by UNSCEAR, the NEA-OECD and the International Commission on Radiological Protection. For scientists, the study provides a detailed baseline, complete with distribution maps and statistical relationships, against which any future changes in the coastal radiological environment can be judged, whether they stem from erosion, coastal development or the slow decay of legacy fallout still working its way through the Black Sea ecosystem.

Subject of Research: Radioactivity levels and radiation hazard indices in beach sands along the Bulgarian Black Sea coast

Article Title: Investigation of the radioactivity of sands collected from Bulgarian Black Sea coast

Article References: Arhangelova, N., & Salim, S. (2026). Investigation of the radioactivity of sands collected from Bulgarian Black Sea coast. BioRisk, 24, 103-117. https://doi.org/10.3897/biorisk.24.178091

Image Credits: AI Generated

DOI: 10.3897/biorisk.24.178091

Keywords: radioactivity, Black Sea, Bulgaria, beach sand, gamma spectrometry, radionuclides, caesium-137, potassium-40, uranium-238, thorium-232, radiation hazard indices, radiological assessment

The radionuclides at the center of the investigation, radium-226 and radium-228, are decay products of the uranium-238 and thorium-232 series that occur naturally in the Earth’s crust. They matter for drinking water because of their chemistry and their biology. Radium is relatively soluble compared with its parent elements, so it leaches readily from minerals into groundwater. Its two isotopes have half-lives long enough to persist in aquifers, 1,600 years for radium-226 and 5.75 years for radium-228, and once ingested the body treats radium much like calcium, depositing it in bone. There, the alpha and beta radiation emitted by the isotopes and their short-lived progeny can irradiate bone tissue, a pathway historically linked to elevated risks of bone cancer and other malignancies. The WHO sets guidance levels of 1.0 becquerel per liter for radium-226 and 0.1 becquerel per liter for radium-228, values designed so that lifetime consumption at those levels would deliver an annual committed effective dose of roughly 0.1 millisieverts.

The analytical backbone of the study was high-purity germanium gamma spectrometry performed at the Radiation Protection Institute in Accra. One-liter samples were sealed in Marinelli beakers and stored for three to four weeks, allowing radium-226 to reach secular equilibrium with its short-lived progeny lead-214 and bismuth-214, and radium-228 to equilibrate with actinium-228. The detector, an N-type HPGe with 25 percent relative efficiency and a resolution of 1.8 kiloelectronvolts at 1332 kiloelectronvolts, was calibrated with a mixed radionuclide standard in identical geometry, and each sample was counted for a demanding 36,000 seconds, ten full hours, to push detection limits as low as possible. Radon-226 was quantified through the 609.3 and 351.9 kiloelectronvolt lines of its progeny, while radium-228 was measured through actinium-228 gamma lines at 911.2 and 968.9 kiloelectronvolts. Even so, the minimum detectable activities were 0.12 becquerels per liter for radium-226 and 0.14 becquerels per liter for radium-228.

That second detection limit turns out to be one of the study’s most consequential technical findings. Because the detection limit for radium-228, 0.14 becquerels per liter, sits above the WHO guidance level of 0.1 becquerels per liter, a non-detect cannot demonstrate compliance. Every sachet and tap water sample in the study, across all three regions and both seasons, returned results below the detection limits for both isotopes. For radium-226, whose detection limit is an order of magnitude below its guidance level, that genuinely establishes compliance. For radium-228, the honest reading is more cautious: the true activity could lie anywhere between zero and 0.14 becquerels per liter, a range that spans the guideline. Treating both detection limits as upper bounds yields a screening dose of 0.095 millisieverts per year, which falls just below, but not comfortably below, the WHO individual dose criterion of 0.1 millisieverts per year. The margin is roughly 5 percent, smaller than the analytical uncertainty of the measurement itself.

The untreated sources told a dramatically different story. Borehole water, the primary drinking supply for peri-urban and rural communities without piped infrastructure, contained 5.03 to 5.16 becquerels per liter of radium-226 and 5.06 to 5.34 becquerels per liter of radium-228, exceeding the WHO guidance levels by factors of roughly five and about 51 to 53 respectively. River water was higher still. Samples from the Densu, Kakum, Pra and Anankwar rivers, along with the Weija and Kpong reservoirs, registered 27.02 to 28.39 becquerels per liter of radium-226 and 29.01 to 30.09 becquerels per liter of radium-228, overshooting the guidance levels by factors of roughly 27 to 28 and 290 to 301. These river values are unusually high for surface water anywhere in the world, and the authors themselves flag that they require independent confirmation before being used for regulatory decisions.

Converting activity into dose, the researchers applied standard ingestion dose coefficients, 2.8 times ten to the minus four millisieverts per becquerel for radium-226 and 6.9 times ten to the minus four for radium-228, multiplied by an assumed consumption of two liters per day, or 730 liters per year. Under the deliberately conservative assumption that an adult drinks exclusively from a single source for an entire year, borehole water delivered a screening dose of 3.58 to 3.73 millisieverts per year, roughly 36 times the WHO criterion, while river water delivered 20.14 to 20.96 millisieverts per year, about 200 times that benchmark and twenty times the 1 millisievert per year reference level of the International Basic Safety Standards. Notably, radium-228 contributed about 70 percent of the total dose in both cases despite similar activity concentrations, because its dose coefficient is roughly 2.5 times larger. The authors stress these are screening values, not measured exposures; anyone who switches between sources would receive less, and no age-resolved estimates were made for children, infants or pregnant women.

Season emerged as a meaningful variable. Wet-season activities exceeded dry-season values in every untreated source and region, with average increases of 1.8 to 4.9 percent. Statistical testing by one-way analysis of variance confirmed the seasonal effect was significant for borehole radium-228, river radium-226 and river radium-228, though not for borehole radium-226. The pattern is consistent with enhanced mineral dissolution, groundwater recharge and catchment runoff during the rains, which mobilize radionuclides from aquifer and catchment materials. Equally telling was what the regional comparison did not find: combined radium activities in river water were nearly identical across the three regions, 57.22, 57.26 and 57.24 becquerels per liter, with no statistically significant differences. The dataset therefore provides no basis for attributing regional variation to differences in underlying geology.

What explains the elevated activities in the untreated sources? The coastal belt is underlain by Precambrian crystalline rocks, Birimian metavolcanics, Tarkwaian sediments and coastal sedimentary basins, all of which host uranium- and thorium-bearing accessory minerals such as monazite, zircon and apatite. Weathering, dissolution and alpha-recoil release of radium from these minerals is the most plausible geogenic source, and the catchments of the Kakum, Pra and Anankwar rivers also host extensive artisanal gold mining that disturbs mineralized material and inflates suspended sediment loads. But the authors are careful: the study measured no hydrogeochemical parameters, performed no mineralogical characterization and conducted no source apportionment, so a geogenic origin remains a hypothesis rather than a demonstrated conclusion. A further technical caveat concerns the river samples themselves. They were collected as unfiltered whole-water samples and acidified to below pH 2, a procedure that leaches radium from suspended particles into solution. The reported values therefore represent total radium, dissolved plus particulate-bound, and likely overstate what a consumer actually absorbs.

The authors are equally explicit about what the exceedances do and do not mean. WHO guidance levels are conservative operational screening criteria, not thresholds of harm, and the 1 millisievert reference level is a trigger for planning protective action rather than a dose limit. The findings, they argue, call for confirmatory sampling by independent laboratories, source-specific investigation, and consideration of treatment, not a declaration of health detriment. Proven radium removal technologies exist, including ion exchange, reverse osmosis, activated alumina and lime softening, and the burden of exposure falls disproportionately on communities with the fewest alternatives to boreholes and rivers. The study also carries a regulatory message: Ghana’s national drinking water standards do not mandate routine radiological testing, and any future monitoring program must specify methods sensitive enough to detect activities below the guidance level, since a method whose detection limit exceeds the criterion cannot demonstrate compliance no matter how many samples are analyzed.

As a piece of baseline science, the work fills a genuine gap. Previous Ghanaian studies focused on mining-impacted areas or single municipalities and reported borehole radium-226 at or below 1 becquerel per liter, far lower than the values found here, which sit at or above the upper end of ranges typical of crystalline-basement aquifers worldwide. The recommended follow-up is concrete: paired raw and treated samples to quantify treatment removal, parallel filtered and unfiltered river sampling to separate dissolved from particulate radium, hydrogeochemical and mineralogical work to test the geogenic hypothesis, and an age-resolved dose assessment grounded in an actual consumption survey. Until then, the image that lingers is one of contrast, of city dwellers sipping radiologically quiet sachet water while, a few kilometers away, families draw water from boreholes and rivers that geology has quietly loaded with radium.

Subject of Research: Naturally occurring radium-226 and radium-228 contamination in drinking water sources along Ghana's coastal regions

Article Title: Assessment of 226Ra and 228Ra activity concentrations in drinking water sources along Ghana’s coastal communities

Article References: Agyeman, B. K., Adukpo, O. K., Adotey, D. K., & Serfor-Armah, Y. (2026). Assessment of 226Ra and 228Ra activity concentrations in drinking water sources along Ghana’s coastal communities. Discover Geoscience, 4(1), Article 397. https://doi.org/10.1007/s44288-026-00765-2

Image Credits: AI Generated

DOI: 10.1007/s44288-026-00765-2

Keywords: radium-226, radium-228, drinking water, Ghana, gamma spectrometry, WHO guidance levels, groundwater, natural radioactivity, radiological assessment, borehole water, river water, public health

The research, published in Environmental Monitoring and Assessment, was carried out by a team from Hassan II University, the Moroccan National Centre for Nuclear Energy, Science and Technology (CNESTEN) and the National Institute of Agricultural Research, working within an International Atomic Energy Agency coordinated research project on radionuclide transfer in arid and semiarid environments. Led by Zineb Elaboudi, the scientists sampled soil and nine commonly consumed crops, including coriander, red pepper, potato, onion, pomegranate, cardoon, beet, tomato and eggplant, from farmland in a semiarid Moroccan agricultural area. Their goal was to quantify activity concentrations, calculate soil-to-plant concentration ratios and estimate the potential annual effective dose that people could receive from eating locally grown food.

The analytical work relied on high-resolution alpha- and gamma-spectrometry using high-purity germanium detectors, instruments capable of distinguishing the characteristic energy signatures of individual isotopes even at very low concentrations. The team measured eight radionuclides in both soil and plants: polonium-210, thorium-234, radium-226, thorium-228, radium-228, lead-210, potassium-40 and cesium-137. Together these isotopes span the full spectrum of environmental radioactivity, from members of the uranium and thorium decay chains that have leached slowly through bedrock for millennia, to potassium-40 dispersed uniformly through all living tissue, to cesium-137, a fission product whose global fallout from mid-twentieth-century nuclear weapons testing still lingers in surface soils.

In the soil, activity concentrations painted a picture of typical natural background. Polonium-210 ranged from 16.37 to 39.59 becquerels per kilogram, thorium-234 from 6.21 to 29.15, radium-226 from 4.84 to 26.26, thorium-228 from 9.37 to 46.04, radium-228 from 10.10 to 51.04, and lead-210 from 5.92 to 31.39. Potassium-40, as expected, dominated with values between 107.21 and 434.20 becquerels per kilogram, while cesium-137, the sole anthropogenic contributor, registered only 1.15 to 2.98 becquerels per kilogram, a faint residue of atmospheric fallout rather than any local contamination source.

Inside the plants, the story changed dramatically. Activity concentrations were generally far lower than in the underlying soil, with polonium-210 between 0.12 and 4.76 becquerels per kilogram, radium-226 between 0.36 and 5.89, and thorium-228 between 0.22 and 1.61. Potassium-40, however, ran in the opposite direction, reaching 386.33 to 3265.53 becquerels per kilogram, sometimes exceeding its soil concentration. The reason is biochemical rather than radiological: potassium is an essential plant macronutrient, recruited in large quantities to regulate osmotic pressure and enzyme function, and potassium-40 constitutes a fixed fraction of all natural potassium. Because the isotope cannot be separated chemically from its stable siblings, plants that accumulate potassium necessarily accumulate its radioactivity. Meanwhile thorium-234, radium-228, lead-210 and cesium-137 mostly fell below detection limits in the crops, indicating that roots act as effective barriers against these species.

The concentration ratio, defined as the activity concentration in plant tissue divided by that in dry soil, is the single most important parameter in radiological dose models, and the Moroccan values revealed striking crop-specific differences. Ratios spanned 0.01 to 0.14 for polonium-210, 0.02 to 0.43 for radium-226, and 0.01 to 0.17 for thorium-228, but climbed as high as 20.03 for potassium-40. Two crops stood out as the strongest accumulators: cardoon, a thistle-like vegetable with deep roots and a place of honor in North African cuisine, and eggplant. Elevated transfer in these species suggests that rooting depth, plant family physiology and nutrient demand all shape which isotopes cross the root membrane, a finding consistent with observations from Syria, Saudi Arabia, Abu Dhabi and other dry regions where comparable studies have been conducted.

Perhaps the most scientifically valuable contribution lies in the correlation analysis linking radionuclide uptake to soil chemistry. The researchers found strong interrelationships among the measured isotopes and demonstrated that transfer processes are governed primarily by soil physicochemical properties, particularly organic matter content, cation exchange capacity and the suite of exchangeable cations held on clay and humus surfaces. These parameters control how tightly radionuclides are bound to soil particles and therefore how available they are for root uptake. In contrast, carbonate content and salinity tended to restrict radionuclide mobility, effectively locking the isotopes in place. This has a counterintuitive implication for semiarid agriculture: the very conditions that make soils challenging for crop productivity, including high carbonate levels and salt accumulation under intense evaporation, may also suppress the movement of radioactive elements into the food chain.

The study also estimated the potential annual effective dose from food ingestion, the standard metric used by the International Commission on Radiological Protection to translate environmental measurements into health-relevant terms. By combining crop activity concentrations with consumption rates and isotope-specific dose coefficients, the team could assess whether locally grown vegetables contribute meaningfully to the radiation burden that residents already receive from cosmic rays, radon and terrestrial gamma radiation. The dominance of potassium-40 in plant tissues means it inevitably drives much of the ingested dose, yet because the human body maintains potassium homeostasis, biologically regulated excretion keeps the internal burden from this isotope essentially constant regardless of dietary source, a nuance that distinguishes potassium-40 from radium or polonium, which follow bone and soft-tissue metabolism and are treated with greater regulatory caution.

For the wider scientific community, the Moroccan dataset fills a recognized gap. The IAEA has repeatedly noted that most soil-to-plant transfer parameters in its handbooks derive from temperate European and North American ecosystems, while arid and semiarid environments, home to a large share of the world’s irrigated agriculture, remain underrepresented. Studies from Turkey, Jordan, Nigeria, Vietnam, Australia and now Morocco are steadily building the evidence base needed to adapt radiological environmental impact assessment to dry climates. The finding that organic matter and cation exchange capacity promote transfer while carbonates and salinity suppress it offers modelers concrete, measurable soil descriptors that can be incorporated into transfer predictions without requiring site-specific experiments at every location.

The practical message for consumers is reassuring. Cesium-137 was barely detectable, the natural radionuclides were mostly well below levels of concern, and the estimated doses fall within the range regarded as normal background exposure from food. Yet the research carries lasting value beyond its immediate conclusions. As phosphate fertilizer use, water scarcity and climate change reshape agriculture across the semiarid world, understanding the soil chemistry that governs radionuclide mobility becomes essential for protecting both food safety and the environmental systems that sustain it. This Moroccan study, rooted in rigorous gamma and alpha spectrometry and framed by international collaboration, demonstrates that even the quiet radioactivity of an ordinary vegetable patch can be measured, modeled and managed with precision.

Subject of Research: Soil-to-plant transfer of natural and artificial radionuclides and associated radiological doses in semiarid Moroccan agriculture

Article Title: Radiological impact of radionuclides in Moroccan food crops under semiarid conditions

Article References: Elaboudi, Z., Aouidi, S. E., Saadi, R., Benkdad, A., Mouridi, Z. E., Laissaoui, A., Madinzi, A., & Souabi, S. (2026). Radiological impact of radionuclides in Moroccan food crops under semiarid conditions. Environmental Monitoring and Assessment, 198(11), Article 1160. https://doi.org/10.1007/s10661-026-15992-w

Image Credits: AI Generated

DOI: 10.1007/s10661-026-15992-w

Keywords: radionuclides, soil-to-plant transfer, concentration ratio, potassium-40, radium-226, polonium-210, cesium-137, semiarid agriculture, Morocco, gamma spectrometry, radiological dose, soil chemistry

The Okpara mine, also known as the Iva Valley mine, has stood unmanaged since its closure, with no post-closure environmental monitoring or containment strategy. That neglect matters because the geology of the Anambra Basin is unforgiving. The Enugu Shale that hosts the coal seams is naturally enriched in uranium and thorium decay chains, meaning the spoil heaps left behind are essentially uncontrolled deposits of naturally occurring radioactive material. When rainwater percolates through these dumps, it generates acid mine drainage, an acidic leachate that mobilizes radium, thorium and other radionuclides and carries them downslope into farmland and waterways. Wind adds a second dispersal pathway, lifting contaminated dust from the spoil piles and scattering it across the surrounding agricultural landscape.

To quantify the hazard, the team collected 24 environmental samples from across the affected area and analyzed them using certified gamma spectrometry, with measurements performed at Activation Analysis Laboratories in Ancaster, Canada, and at the Centre for Energy Research and Training at Ahmadu Bello University in Zaria, Nigeria. The technique identifies and quantifies gamma-emitting isotopes, allowing the researchers to determine activity concentrations of potassium-40, radium-226 and thorium-232 in each sample. From these measurements they derived eight separate hazard indices, all compliant with the assessment frameworks of the United Nations Scientific Committee on the Effects of Atomic Radiation and the International Commission on Radiological Protection, and they estimated dietary ingestion doses based on local cassava consumption, a staple crop grown throughout the valley.

The numbers are striking. Mean activity concentrations of radium-226 reached 51.23 plus or minus 11.79 becquerels per kilogram, exceeding the global average by a factor of 1.46, while thorium-232 averaged 68.86 plus or minus 16.45 becquerels per kilogram, a factor of 2.30 above the worldwide benchmark. The mean outdoor gamma dose rate of 75.64 nanograys per hour surpassed the world average in 87.5 percent of the samples collected. In practical terms, people living and farming in the valley are receiving measurably higher external gamma exposure than the global baseline, simply from the ground beneath their feet.

But the most alarming finding concerns what residents eat. The mean annual dietary ingestion dose was calculated at 2.43 millisieverts per year, exceeding the ICRP public exposure limit of 1 millisievert per year in every single sample, and radium-226 accounted for 68.8 percent of that total dose. Radium’s dominance on the ingestion pathway stems from its relatively high ingestion dose conversion factor, meaning each becquerel consumed delivers a larger effective dose than the same activity of thorium or potassium-40. Because cassava efficiently transfers radium from contaminated soil into its edible tubers, and because cassava forms such a large share of the local diet, the food chain acts as a powerful concentrating mechanism, funneling subsurface radioactivity directly into the bodies of the community.

The statistical structure of the hazard is also revealing. Thorium-232 emerged as the dominant contributor to the calculated outdoor gamma dose, accounting for roughly 55 percent of the outdoor dose rate with a strong correlation coefficient of R-squared equal to 0.804 and a p-value below 0.0001, while radium-226 dominates the ingestion pathway. This split reflects the different physics of the two exposure routes: thorium’s decay chain emits abundant gamma radiation that irradiates the body externally, whereas radium, chemically analogous to calcium, is readily absorbed through the gut and deposited in bone tissue, where its alpha emissions do the most biological damage. The excess lifetime cancer risk, calculated at a mean of 3.25 times ten to the minus four, exceeded global benchmarks in 66.7 percent of cases, translating into a measurable elevation of lifetime cancer probability for people who live and farm in the most contaminated zones.

Spatial analysis added a crucial layer of precision. Using cubic interpolation of the sample data, the researchers mapped contamination gradients across the valley and found that peak concentrations track the acid mine drainage axis in the central-eastern sector of the site. This pattern confirms the mechanistic picture: the acidic drainage channels act as radioactive highways, carrying radium and thorium from the spoil heaps outward into the fields where food is grown. The mapping also carries practical value for remediation, because it identifies exactly where containment and treatment efforts would deliver the greatest reduction in community dose.

The study also uncovered a regulatory blind spot with immediate construction implications. The representative level index, a screening tool used to judge whether earth materials are safe for building, exceeded the threshold value of 1.0 in 75 percent of samples, classifying those materials as unsuitable for unrestricted construction use. Yet in many Nigerian communities, mine spoil and local soil are routinely used for bricks, road fill and foundations, often without any radiological screening. The finding suggests that the hazard extends beyond farming into the built environment, and that material sourcing decisions in the valley may be compounding exposure without anyone realizing it.

What makes the Iva Valley case particularly significant is its comparative severity. According to the comparative data available at the time of writing, the authors identify the site as the most severe documented case of dietary radionuclide burden at a West African coal mine legacy site. It is also a warning about a broader, largely invisible class of risk. Coal mining worldwide disturbs formations that naturally contain uranium and thorium, and abandoned mines across Africa, Asia and Latin America sit unmonitored beside growing populations. Nigeria alone hosts numerous legacy extraction sites where naturally occurring radioactive materials have never been systematically surveyed, and previous studies have flagged elevated radioactivity around gold, tin and coal operations across the country.

The researchers call for immediate interventions, including treatment of the acid mine drainage, physical containment of the spoil heaps, agricultural restrictions in the most contaminated zones, and systematic monitoring of naturally occurring radioactive materials aligned with international safety standards. None of these measures currently exists at the site. The study’s message is ultimately about time: every year of inaction extends the exposure of 50,000 people through the food they eat, the dust they breathe and the ground they walk on. A mine that closed decades ago is still, in a very literal sense, radiating consequences into the present, and the Iva Valley results make a compelling case that legacy mining sites across the region deserve urgent radiological assessment before the hidden burden grows heavier still.

Subject of Research: Radiological hazard assessment of natural radionuclide contamination from a legacy coal mine in Enugu Iva Valley, Nigeria

Article Title: Elevated radiological hazards in a legacy coal mining area: unveiling hidden cancer risks from natural radionuclides in Enugu Iva Valley, Southeast Nigeria

Article References: Omeje, M., Sabri, S., Owusu-Appiah, J., Gyaase, D., & Orosun, M. M. (2026). Elevated radiological hazards in a legacy coal mining area: unveiling hidden cancer risks from natural radionuclides in Enugu Iva Valley, Southeast Nigeria. Environmental Geochemistry and Health, 48(15), Article 624. https://doi.org/10.1007/s10653-026-03502-3

Image Credits: AI Generated

DOI: 10.1007/s10653-026-03502-3

Keywords: natural radioactivity, radium-226, thorium-232, coal mining legacy, acid mine drainage, cancer risk, Enugu Shale, cassava, gamma spectrometry, Nigeria, ICRP, radiological hazard

The team collected thirty-eight soil samples from across the district, preparing them under controlled laboratory conditions before analysis. The measurement technique of choice was gamma ray spectrometry using a high-purity germanium detector, an instrument prized in radiation science for its exceptional energy resolution. Unlike simpler sodium iodide detectors, high-purity germanium crystals can separate the closely spaced gamma ray lines emitted by different radionuclides, allowing researchers to identify and quantify specific isotopes with confidence. In this study, the detector was calibrated and used to measure the activity concentrations of three radionuclides that dominate the natural radiation environment: potassium-40, thorium-232, and radium-226, the latter serving as a proxy for the uranium decay chain in soil.

The results reveal a clear hierarchy among the three isotopes. Potassium-40, a long-lived isotope that makes up a tiny fraction of all natural potassium, showed the highest activities, ranging from 342 plus or minus 10 to 760 plus or minus 16 becquerels per kilogram, with an average of 568 becquerels per kilogram. Thorium-232 activities ranged from 35 plus or minus 1.0 to 83 plus or minus 3.4 becquerels per kilogram, averaging 55 becquerels per kilogram, while radium-226 ranged from 48 plus or minus 1.9 to 90 plus or minus 3.7 becquerels per kilogram, with a mean of 65 becquerels per kilogram. These values sit within the ranges typically reported for soils worldwide, though the upper end of the potassium-40 distribution is notable, reflecting the mineralogy of the local geological formations from which the soils derive.

What makes the study more than a simple catalog of numbers is its statistical treatment of the data. Because environmental radioactivity measurements are frequently skewed by outliers and by the heterogeneous nature of soil, the authors first applied the Shapiro-Wilk test to assess whether the activity distributions followed a normal distribution. This test, widely regarded as one of the most powerful normality tests for moderate sample sizes, informs which subsequent statistical tools are appropriate. The researchers then employed the Spearman rank correlation test, a non-parametric method that measures monotonic relationships without assuming linearity or normality, to probe whether the three radionuclides vary together across sampling sites. Strong positive correlations between radionuclides can indicate a shared mineralogical origin, for example when uranium, thorium, and potassium-bearing minerals are concentrated together in the same parent rocks and weathering products.

To investigate whether the underlying geology, or lithology, exerts a measurable influence on radionuclide levels, the team turned to the Kruskal-Wallis test, a non-parametric analysis of variance that compares multiple groups without requiring normally distributed data. Gurugram’s geology is diverse, with the Aravali hill range skirting the district and alluvial plains covering much of its area, so differences in radionuclide concentrations between zones with different geological character are scientifically expected. The combination of these tests, descriptive statistics, normality assessment, rank correlation, and group comparison, represents a methodologically rigorous framework that is increasingly standard in environmental radioactivity studies, allowing researchers to distinguish genuine geological signals from random spatial variation.

Beyond characterizing the distribution of radionuclides, the study translated its measurements into quantities that matter for human health. From the measured activity concentrations, the authors calculated the absorbed gamma dose rate in air, which describes the energy deposited by gamma radiation per unit mass of air at ground level, and from that the annual effective dose rate for both indoor and outdoor exposure scenarios. Indoor doses are typically weighted more heavily in radiological assessments because people spend the majority of their time inside buildings, where gamma rays from construction materials derived from soil add to the outdoor background. The comparison of these derived doses with reference values established by international agencies such as the United Nations Scientific Committee on the Effects of Atomic Radiation provides the practical yardstick for judging whether the measured levels pose any concern to the public.

The team also computed two widely used screening indices. The gamma index, which ranged from 0.48 to 0.95 across the sampled soils, is designed to flag materials whose gamma radiation could become significant if used in building construction; values below unity are generally considered acceptable under international guidance. The alpha index, which ranged from 0.24 to 0.45, serves as a screening tool for potential radon inhalation hazards associated with radium-226 content, since radon-222 is a radioactive gas in the uranium decay chain that can accumulate in enclosed spaces. Both indices remained below their conventional thresholds across all thirty-eight samples, indicating that the natural radioactivity of Gurugram’s soils falls within the range considered safe for ordinary exposure and typical construction use.

The Gurugram survey is the latest entry in a growing body of work on natural radioactivity across northern India, much of it involving overlapping research groups. Previous studies by the same lead author and collaborators have examined radon and thoron exhalation from Gurugram soils, radionuclides in the soils of neighboring Palwal district, seasonal and geological influences on gamma radiation in Faridabad, and radon doses from groundwater in the same region. Parallel investigations elsewhere in Haryana and Punjab, including assessments of Rohtak, Jind, Bathinda, and Sirsa, and geospatial surveys of urban soils in Chennai, contribute to a national picture in which terrestrial gamma dose varies principally with local geology rather than with human activity. Such baseline datasets are valuable not only for radiation protection but also as reference points against which any future anthropogenic contamination, whether from industrial activity, construction, or accidents, could be detected and quantified.

For the residents of Gurugram, the practical message of the study is reassuring: the natural radioactivity of the district’s soils, from the potassium-rich alluvium to the thorium-bearing sediments near the Aravalis, produces radiation doses that international agencies would classify as within normal background levels. But the scientific significance runs deeper. As urbanization transforms land use across the National Capital Region, soils that once lay undisturbed are being excavated, processed into building materials, and incorporated into the homes and offices of millions. Understanding the radiological properties of that raw material, and the geological factors that control its variability, is a quiet but essential piece of public health infrastructure. With rigorous measurement, transparent statistics, and comparison against international standards, this study demonstrates how even an invisible, omnipresent hazard can be brought into sharp, quantifiable focus.

Subject of Research: Measurement of natural radionuclides and radiological hazard assessment in soils of Gurugram district, India

Article Title: Monitoring of natural radionuclides in soil of District Gurugram, Haryana (India), by gamma spectrometry and statistical analysis

Article References: Singh, B., Gupta, U., Kant, K., Yadav, S., & Tanwer, N. (2026). Monitoring of natural radionuclides in soil of District Gurugram, Haryana (India), by gamma spectrometry and statistical analysis. Environmental Monitoring and Assessment, 198(10), Article 1106. https://doi.org/10.1007/s10661-026-15925-7

Image Credits: AI Generated

DOI: 10.1007/s10661-026-15925-7

Keywords: natural radioactivity, gamma spectrometry, potassium-40, thorium-232, radium-226, soil, Gurugram, Haryana, radiation dose, gamma index, statistical analysis, environmental monitoring

The study, published in the journal Discover Oceans, involved measuring gamma radiation at thirty locations spread across an area of roughly two kilometres by six hundred metres, arranged on an imaginary grid with two hundred metres between adjacent points. The researchers used a portable sodium iodide detector sealed inside a PVC pipe to record total gamma counts directly on the beach, logging each position with a handheld GPS receiver. Back in the laboratory, sediment collected from the same thirty sites was dried, sieved and analysed with a high-resolution germanium detector to quantify specific radionuclides. The in-situ counts ranged from 1800 to 6498 counts per minute, and the interpolated map showed that radioactivity was noticeably higher toward the south-west of the beach than the north-east.

What makes the pattern scientifically interesting is that different radionuclides behave in opposite ways depending on the size of the sand grains they inhabit. In the finest fraction studied, grains between 53 and 100 micrometres, the mean activity concentrations of radium-226, radium-228 and potassium-40 were 151.2, 369.4 and 209.7 becquerels per kilogram respectively. In the dominant medium fraction, between 101 and 250 micrometres, the same isotopes averaged just 28.7, 60.6 and 272.6 becquerels per kilogram. In other words, radium concentrates in fine grains while potassium-40 favours coarse ones, a split that reflects two entirely different geochemical stories.

The radium story is one of surface chemistry. Radium-226 and radium-228 are daughter products of the uranium-238 and thorium-232 decay chains, and both isotopes are strongly adsorbed onto particle surfaces. Fine grains carry far more surface area per unit mass than coarse grains, so they adsorb more radium from seawater and pore fluids. Potassium-40 behaves differently: it is an integral constituent of silicate minerals derived from igneous rocks, and its compatibility with silica means it travels locked inside the mineral lattice rather than clinging to grain surfaces. Coarse sediments, being richer in such minerals and less easily washed back out by the tide, end up enriched in potassium-40. The tidal sorting mechanism is simple but effective: waves wash lighter fine grains away and leave heavier particles behind on the beach.

To characterise the sediments chemically, the team used energy-dispersive X-ray fluorescence on the medium grain fraction, which makes up more than seventy percent of the sediment by weight at most locations. The dark grey sand proved mineral-rich, with iron, aluminium, calcium, magnesium, titanium, potassium, vanadium, manganese, zirconium, chromium and lanthanum as the major elements. Mean iron concentration reached about 84,900 parts per million, with aluminium near 54,000 and calcium around 50,000 parts per million. This composition points to substantial heavy-mineral content, the kind of material that waves and currents concentrate into placers and that can markedly raise local radioactivity, as seen dramatically in the monazite-rich black sands of Kerala on India’s south-west coast.

Compared with other Indian and international beaches, Jampore sits in a middle ground. Kerala’s high-background radiation area shows thorium-232 activities that can reach thousands of becquerels per kilogram, far beyond anything measured at Daman. Tamil Nadu beach sands typically report radium-226 between 13 and 198 becquerels per kilogram, while the Odisha and Andhra coasts fall in the tens to low hundreds. Globally, beaches in Ghana, Turkey and Thailand report broadly similar values, with radium isotopes in the tens and potassium-40 in the low hundreds of becquerels per kilogram. Jampore’s fine fraction is moderately elevated relative to many of these sites, but remains well below the classical high-background zones, meaning the beach is radiologically ordinary while still being dynamically informative.

The most consequential finding concerns the ratio of the two radium isotopes. Across the fine fraction the radium-226 to radium-228 ratio ranged from 0.29 to 0.55, and in the medium fraction from 0.39 to 0.61. Crucially, zones with lower ratios coincided with higher total gamma counts. Building on earlier work in the Yangtze Estuary, where smaller radium ratios were linked to sediment accretion, the researchers interpret the low-ratio, high-count areas of Jampore beach as zones where sand is accumulating. The strong linear correlation between the two radium isotopes, with a coefficient of determination of 0.9878, suggests they share a common origin and are governed by the same adsorption and desorption processes, which makes their ratio a stable and interpretable indicator.

The in-situ measurements also proved to be a surprisingly faithful proxy for laboratory analysis. Correlation plots showed that the spatial pattern of total gamma counts closely mirrors the distributions of both radium-226 and radium-228, but not potassium-40. The reason lies in nuclear structure: the uranium and thorium series emit multiple high-intensity gamma lines, including strong peaks at 609.3 and 1764.5 kiloelectronvolts for the radium-226 chain and at 583.2 and 2614.5 kiloelectronvolts for the radium-228 chain, whereas potassium-40 emits only a single gamma ray at 1460.82 kiloelectronvolts with a modest ten percent emission probability. The integrated field signal is therefore dominated by the radium chains, which is precisely what makes a rapid field survey with a portable detector a viable stand-in for detailed laboratory spectrometry when the goal is mapping sediment regimes.

The broader motivation is methodological. Since 1954, investigations of coastal sediment dynamics have relied on artificial radiotracers produced in nuclear reactors, materials that are effective but burdened by public concern and strict regulatory clearance requirements from nuclear safety authorities. Natural radionuclides embedded in the sediment offer an alternative that requires nothing to be released. Researchers in Spain, the Canary Islands, South Africa and elsewhere have already proposed radium isotopes and lead-210 as tracers of erosion and accretion, and the Indian team frames its Jampore survey as a first step toward establishing a radiometric database and a methodology for using natural isotopes as tracers along Indian coasts. The data could also serve as benchmarks against which numerical sediment transport models can be validated, increasing confidence in their predictions.

For a beach flanked by the mouths of the Daman Ganga and Kolak rivers, where fluvial supply, wave sorting and monsoon-driven erosion continuously redistribute the sand, the ability to read accretion and erosion directly from the sediment’s own radioactivity is a genuinely practical tool. Harbour dredging, dumping-site selection and coastal protection all depend on knowing where sediment goes, and a technique that replaces costly and regulated artificial tracers with a portable detector and a GPS unit could change how coastal engineers gather that knowledge. The Jampore map is a modest survey of one four-and-a-half-kilometre beach, but it demonstrates a principle with wide reach: every shoreline already carries its own radioactive diary of movement, and learning to read it may be as simple as walking the sand with a detector in hand.

Subject of Research: Spatial distribution of natural radioactivity in beach sediments as a tracer of coastal sediment dynamics

Article Title: Investigation of distribution pattern of natural radioactivity in the sediments of Jampore beach, Daman, India

Article References: Biswal, J., Goswami, S., Yadav, V. B., Sartandel, S. J., Samantray, J. S., Pulhani, V., & Sharma, V. K. (2026). Investigation of distribution pattern of natural radioactivity in the sediments of Jampore beach, Daman, India. Discover Oceans, 3(1), Article 12. https://doi.org/10.1007/s44289-026-00124-6

Image Credits: AI Generated

DOI: 10.1007/s44289-026-00124-6

Keywords: natural radioactivity, Jampore beach, Daman, sediment dynamics, gamma spectrometry, radium-226, radium-228, potassium-40, heavy minerals, coastal erosion, accretion, EDXRF

The review, led by S. Veerasingam and colleagues at Qatar University’s Environmental Science Center, followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, searching Google Scholar alongside Web of Science, PubMed, and Scopus for peer-reviewed studies and national monitoring reports. The team compiled data across an unusually diverse set of environmental matrices: terrestrial soils, marine sediments, seawater, groundwater, building materials ranging from cement to steel slag, and marine organisms as varied as pearl oysters, shrimp, sponges, mangroves, and even the dugong, the region’s iconic sea cow. Measurements were dominated by high-purity germanium gamma spectrometry, often supplemented by sodium iodide detectors for screening and, in some studies, inductively coupled plasma mass spectrometry for ultra-trace analysis of plutonium isotopes and strontium 90.

Qatar’s radiological character is written in its geology. The peninsula sits on carbonate-rich Eocene formations, principally the Rus and Dammam formations, whose limestones and evaporites host the primordial radionuclides uranium 238, thorium 232, and potassium 40, along with decay products such as radium 226. Carbonate rocks tend to immobilize uranium and radium through co-precipitation with calcium carbonate, while clay-rich and phosphatic strata preferentially hold thorium and potassium isotopes. The hyper-arid climate amplifies these geochemical controls: with minimal rainfall, leaching is negligible, so radionuclides accumulate in surface soils and sabkha salt flats rather than migrating downward. High evaporation rates raise salinity and ionic strength, further fixing radium and uranium onto carbonate and sulfate minerals.

The numbers tell a consistent story. Mean uranium 238 activities in Qatari soils ranged from 2.46 to 213.9 becquerels per kilogram depending on location, radium 226 typically averaged around 17.2 becquerels per kilogram, thorium 232 spanned 0.42 to 20 becquerels per kilogram, and potassium 40 ranged from 10 to 327 becquerels per kilogram. Compared with the global averages reported by the United Nations Scientific Committee on the Effects of Atomic Radiation, 33 becquerels per kilogram for uranium 238, 45 for thorium 232, and 420 for potassium 40, Qatar’s natural background sits comfortably low. Marine sediments echoed this pattern, with cesium 137, the fingerprint of mid-twentieth-century atmospheric nuclear weapons testing, detected at a maximum of only 0.66 becquerels per kilogram, and many samples falling below detection limits altogether.

Artificial radionuclides across the country are essentially relics of global fallout rather than evidence of local contamination. Cesium 137 in surface soils ranged from below detection to 7.99 becquerels per kilogram, strontium 90 averaged just 3.364 becquerels per kilogram, and plutonium isotopes appeared only at trace levels. In seawater within Qatar’s Exclusive Economic Zone, cesium 137 concentrations of roughly 1.5 to 1.65 becquerels per cubic meter align closely with measurements from Kuwaiti waters and the Indian Ocean, confirming their origin in historic weapons testing dispersed through the stratosphere before the Partial Nuclear Test Ban Treaty of 1963. Notably, a meta-analysis of depleted uranium in the Middle East found no contamination in Qatar, in contrast to several neighboring countries affected by the Gulf wars.

Groundwater tells a more nuanced story. A nationwide survey of 48 wells measured radon 222, a short-lived gaseous decay product of uranium 238, at concentrations ranging from 2.7 to 60.7 becquerels per liter, with a mean of 20.65. Nearly half of the analyzed drinking water samples exceeded the United States Environmental Protection Agency’s maximum contamination level of 11.1 becquerels per liter. Yet the estimated total annual effective dose from radon inhalation and ingestion, 0.056 millisieverts per year, remained below the World Health Organization’s recommended limit of 0.1 millisieverts per year. Intriguingly, inhalation contributed more than ingestion, a reminder that radon’s volatility makes indoor air, not drinking water, the dominant exposure route in confined spaces.

The review’s most consequential findings concern technologically enhanced naturally occurring radioactive material, or TENORM, generated by Qatar’s hydrocarbon industry. Oil and gas operations, particularly at the onshore Dukhan field, produce scales, drilling muds, and sludges in which radium isotopes concentrate during extraction and processing. Soil near Dukhan showed radium 226 values up to 342 becquerels per kilogram, nearly ten times the global average, and sludge collected from oil-field separation tanks reached a radium equivalent activity of 14,678 becquerels per kilogram, against a recommended safety threshold of 370. Calculated absorbed dose rates in this sludge hit 6,778 nanograys per hour, the annual effective dose equivalent reached 8.313 millisieverts per year, roughly seven times the public dose limit, and the external hazard index climbed to 39.67. The authors stress these figures represent localized occupational and waste-management scenarios, not public exposure, but they underscore why handling, storage, transport, and disposal of TENORM residues require stringent controls.

Industrial by-products recycled into construction raise parallel concerns. Steel slag used in road construction exhibited radium 226 concentrations of 273.2 becquerels per kilogram and thorium 232 of 135.2, pushing its radium equivalent activity to between 467 and 522 becquerels per kilogram, above the safety threshold, with hazard indices exceeding unity. By contrast, conventional materials such as cement, sand, gypsum, clinker, and gabbro aggregates all fell well within international limits, with hazard indices between 0.03 and 0.31 and excess lifetime cancer risk estimates for natural soils averaging 0.12 per thousand, below the global average of 0.29 per thousand. The message is clear: Qatar’s buildings are radiologically safe, but screening of recycled industrial residues before reuse is essential to prevent long-term indoor exposure.

Dust storms add a dynamic dimension to the picture. Winds sweeping from local sabkhas and deserts, and from as far as northern Saudi Arabia and Iraq, transport fine mineral particles enriched in adsorbed radionuclides, with airborne dust showing uranium 238, thorium 232, and potassium 40 concentrations two to three times higher than local soils. Prevailing northwesterly Shamal winds can also carry trace cesium 137 from distant sources, and the semi-enclosed circulation of the Arabian Gulf allows limited marine redistribution near the boundaries of Qatar’s Exclusive Economic Zone. Although these transboundary inputs remain radiologically insignificant, the authors argue they justify regional cooperation, particularly given operational and planned nuclear power plants in neighboring countries and the potential for atmospheric or marine transport following any incident.

Looking forward, the review lays out an ambitious research and policy agenda aligned with Qatar National Vision 2030. Priorities include a long-term nationwide monitoring program spanning terrestrial, freshwater, coastal, and marine ecosystems; isotopic fingerprinting to distinguish natural, technologically enhanced, and anthropogenic radionuclides; site-specific transfer coefficients for arid environments, since most existing parameters derive from temperate ecosystems; and formal ecological risk assessments using frameworks such as the International Atomic Energy Agency’s ERICA approach. The authors also champion emerging digital tools, artificial intelligence, machine learning, geographic information systems, remote sensing, and Internet of Things sensor networks, for near-real-time surveillance and automated risk mapping, alongside integration with the IAEA’s International Radiation Monitoring Information System. For now, the baseline is established: Qatar’s natural environment radiates little more than gentle desert sunshine in particle form, while its industrial wastes, if left unmanaged, could tell a very different story.

Subject of Research: Environmental radioactivity and radiological risk assessment of natural and artificial radionuclides across environmental matrices in Qatar

Article Title: Risk assessment of radionuclides in different environmental matrices in the State of Qatar, Arabian Gulf

Article References: Veerasingam, S., Vinothini, V., Ranjani, M., Mohammad, R. E. A., Suresh, G., Rajendran, S., Sadasivuni, K. K., Ghani, S., & Al-Khayat, F. (2026). Risk assessment of radionuclides in different environmental matrices in the State of Qatar, Arabian Gulf. Environmental Geochemistry and Health, 48(14), Article 582. https://doi.org/10.1007/s10653-026-03469-1

Image Credits: AI Generated

DOI: 10.1007/s10653-026-03469-1

Keywords: radionuclides, Qatar, environmental radioactivity, TENORM, radiological risk assessment, gamma spectrometry, oil-field sludge, cesium-137, radon, Arabian Gulf, building materials, dust storms

Every beach on Earth carries a faint trace of the planet’s geological origins. Primordial radionuclides, including uranium-238, radium-226, thorium-232 and potassium-40, have existed since the formation of the Earth and are incorporated into the minerals that make up sand, rock and soil. In most coastal environments, these isotopes occur at modest concentrations that pose little concern. But where heavy minerals accumulate, sands can become strikingly radioactive. The Visakhapatnam coast, with its complex geology and active sediment transport, proved to be exactly such a place, and measuring it required laboratory instrumentation of the highest sensitivity.

The research team collected beach sand samples from locations along the coastline and analysed them using a high-purity germanium gamma spectrometry system, a technique prized for its ability to resolve the characteristic gamma-ray signatures emitted by individual radionuclides. High-purity germanium detectors, cooled to reduce thermal noise, can distinguish the faint energy lines of uranium, radium, thorium and potassium decay chains from the background of ambient radiation, allowing precise quantification of each isotope’s activity concentration in units of becquerels per kilogram. The researchers also measured ambient radiation levels directly on the beaches to connect their laboratory findings to real-world exposure conditions.

The results were remarkable. Activity concentrations of uranium-238 ranged from 8.9 to 868 becquerels per kilogram, with a mean of 167. Radium-226 spanned from 2.8 to 1,282.8, averaging 292. The most dramatic findings concerned thorium-232, which ranged from 6.9 to a staggering 13,691.7 becquerels per kilogram, with a mean of 2,614, while potassium-40 ranged from 77.2 to 1,191.1 with a mean of 449. Each of these mean values exceeds the global averages reported for ordinary soils and sediments, and the thorium figures in particular place the most enriched samples firmly in the territory of monazite-bearing sands, the mineral that has made parts of the Indian coastline famous among radiation scientists for decades.

Thorium’s dominance in these sands is no accident. Monazite, a phosphate mineral rich in thorium and rare earth elements, is a hallmark of India’s eastern and southwestern coastal placer deposits. When waves and longshore currents sort sediments by density and grain size, heavy resistant minerals such as monazite, zircon and ilmenite become concentrated into placer deposits, while lighter quartz is winnowed away. Because thorium and its decay products are locked into monazite’s crystal lattice, these deposits act as natural concentrators of radioactivity. The measured absorbed gamma dose rates on the Visakhapatnam beaches, the study found, are comparable to those in monazite-rich high background radiation areas in India and worldwide, confirming that the same mineralogical processes are at work here.

One of the study’s most valuable contributions is its mapping of spatial variability. Rather than presenting a single average figure, the researchers generated spatial distribution maps that visualize the heterogeneity of radionuclide concentrations along the entire study area. These maps revealed a clear pattern: radioactivity levels rise consistently toward the northern sector of the coastline. This gradient likely reflects the interplay of sediment sources, wave-driven transport directions and the geomorphology of the coast, which ranges from sandy beaches to rocky headlands between Visakhapatnam and Bhimunipatnam. The authors also observed that radioactivity varied across the width of individual beaches, meaning that a visitor standing at the waterline may be on sand with a different radiological character than sand collected near the dunes or backshore.

To translate raw activity concentrations into statements about human risk, the team computed a battery of internationally recognized radiological hazard indices. These included radium equivalent activity, which combines the contributions of the uranium and thorium series and potassium into a single comparable quantity; the absorbed gamma dose rate, which estimates the energy deposited in air per unit time; the annual effective dose equivalent, which converts that dose into a projection of yearly health-relevant exposure; the gamma level index; and the external and internal hazard indices used in building-material and land-use assessments. Together, these indices allow the Visakhapatnam data to be compared directly with safety benchmarks established by bodies such as the United Nations Scientific Committee on the Effects of Atomic Radiation and the International Commission on Radiological Protection.

The researchers went beyond measurement and mapping by applying statistical analyses to the relationships among the radionuclides themselves. Correlation analysis indicated a strong relationship between the radium series and the thorium series, a signature that the authors interpret as evidence of a common geological origin for the two decay chains. This makes geochemical sense: both uranium and thorium series isotopes tend to reside in the same heavy mineral phases, so their concentrations rise and fall together as those minerals are concentrated or diluted in the sand. Such correlations transform a set of isolated numbers into a coherent narrative about where the sand comes from and how the coast has sorted it over time.

It is important to keep the findings in perspective. Natural radioactivity in beach sand is not the same as contamination from human activity; these radionuclides are part of the Earth’s crust and have always been present. Millions of people worldwide live safely in high background radiation areas, including the well-studied monazite sands of Chhatrapur in Odisha and regions of Brazil, China and Kerala. What the Visakhapatnam study provides is a rigorous, spatially resolved baseline against which any future changes, whether from coastal engineering, sediment redistribution, or industrial development, can be judged. Baseline data of this quality are the foundation of long-term environmental monitoring and credible radiological risk assessment in coastal ecosystems.

The study also carries a broader message about how science sees ordinary landscapes. A beach that appears uniform to the eye is, to a gamma spectrometer, a patchwork of geological history written in decaying atoms. By combining sensitive nuclear instrumentation, spatial mapping and statistical interpretation, the researchers have shown that radioactivity along a single coastline can vary by three orders of magnitude within short distances. For coastal managers, public health authorities and the millions who visit these shores, the work of Ramesh and his colleagues offers both a caution about localized hotspots and a model of how careful, transparent measurement can turn invisible hazards into mapped, understood and monitorable features of the environment.

Subject of Research: Natural radionuclide distribution and radiological hazard assessment in beach sands of the Visakhapatnam coast, India

Article Title: Spatial distribution of natural radionuclides and radiological hazard assessment in beach sands of the Visakhapatnam coast, Eastern India

Article References: Ramesh, B., Savitri, P. P., Sudhakar, J., Kumar, R. B., Sahoo, S. K., Saradhi, I. V., & Pulhani, V. (2026). Spatial distribution of natural radionuclides and radiological hazard assessment in beach sands of the Visakhapatnam coast, Eastern India. Environmental Monitoring and Assessment, 198(10), Article 1113. https://doi.org/10.1007/s10661-026-15926-6

Image Credits: AI Generated

DOI: 10.1007/s10661-026-15926-6

Keywords: natural radioactivity, gamma spectrometry, beach sand, thorium-232, radium-226, monazite, Visakhapatnam, radiological hazard, spatial distribution, coastal environment, high background radiation, Environmental Monitoring and Assessment

The research, conducted by Blessing N. Ben-Festus and Festus Ben of the Centre for Advanced Materials Research and Development at Federal Polytechnic Ede in Nigeria, with Ben also affiliated with the Centre for Nanoengineering and Advanced Materials at the University of Johannesburg, focused on sediments within a tropical river estuarine system in southwestern Nigeria. The fieldwork was carried out in a waterway shaped by seasonal rainfall and runoff, artisanal and urban pressures, and the steady downstream delivery of weathered material from the surrounding landscape. Regions of this kind are often underrepresented in global radiological databases, which historically have emphasized temperate environments, making the new dataset a valuable reference point not only for Nigeria but for comparative assessments of depositional environments worldwide.

Technically, the study relied on gamma-ray spectrometry, the workhorse technique of environmental radiochemistry. Sediment samples collected from the estuary were prepared, sealed to allow radioactive equilibrium to be established, and then quantified using a calibrated sodium iodide detector, a scintillation-based instrument that records the characteristic gamma-ray energies emitted by decaying nuclides. Sodium iodide spectrometers are prized in field-adjacent laboratories for their high detection efficiency and relatively low cost, although they demand careful energy and efficiency calibration to resolve the photopeaks of interest. The authors followed established calibration practice, drawing on the well-documented performance characteristics of 3-inch by 3-inch NaI(Tl) detectors, to convert counts into activity concentrations expressed in becquerels per kilogram, a unit that describes the number of radioactive decays per second in each kilogram of dry sediment.

The measured activity concentrations told a consistent story. Potassium-40, the primordial isotope that has persisted since the formation of the Earth and pervades virtually all crustal material, averaged 490.50 plus or minus 7.66 becquerels per kilogram across the samples. Uranium-238, the head of the uranium decay series, averaged just 5.67 plus or minus 0.20 becquerels per kilogram, and thorium-232, the progenitor of the thorium series, registered 4.81 plus or minus 0.26 becquerels per kilogram. Benchmarked against the reference values published by the United Nations Scientific Committee on the Effects of Atomic Radiation, the potassium result ran about 16.79 percent above the global average, a modest elevation the authors attribute to the potassium-rich minerals weathered from the catchment’s bedrock and soils. By contrast, the uranium and thorium figures sat far below the corresponding global thresholds, at 82.82 percent and 89.31 percent below them, respectively, underscoring how strongly the local geology, rather than industrial contamination, controls the radiological signature of these deposits.

Raw concentrations, however, are only the starting point of a radiological risk assessment. Because potassium-40, uranium-238 and thorium-232 differ in the energy and intensity of the gamma radiation they emit, regulators and researchers combine them into derived indices that better approximate real-world exposure. The study calculated the radium equivalent activity, a composite quantity that weights the three nuclides according to their relative gamma dose contributions, and obtained a mean value of 50.32 becquerels per kilogram, well under the widely cited 370 becquerels per kilogram ceiling that marks the threshold above which structural or land-use restrictions might be considered. This single number already suggests that neither beachcombers nor construction workers handling dredged sediment would encounter unusual radiation fields at the site.

The dose-based indicators reinforce that conclusion. The absorbed gamma dose rate in air at one meter above the sediment surface averaged 26.13 nanogray per hour, translating into an annual effective dose of roughly 0.03 millisievert per year for a member of the public spending typical time near or on the sediments. For context, the global average outdoor terrestrial dose attributable to natural radionuclides is generally estimated at around 0.07 millisievert per year, meaning the Nigerian estuary delivers less than half of that conventional background. The team also evaluated the annual gonadal dose, a quantity used to approximate the genetically significant dose to reproductive organs, obtaining 191.64 microsieverts per year, again comfortably below the internationally recognized screening level of about 300 microsieverts per year. Taken together, these parameters indicate that external exposure pathways linked to the estuary’s sediments pose no significant radiological risk to the surrounding communities.

The findings matter for reasons that extend beyond a single river. Sediments are the memory of a river system: they trap not only radionuclides but also heavy metals, nutrients and pollutants, and their radioactive inventory reflects the interplay of bedrock composition, weathering intensity, grain-size sorting and hydrodynamic energy. In tropical climates, intense rainfall and episodic flooding periodically resuspend and redistribute these deposits, meaning that a baseline established today is the essential yardstick against which future disturbance, whether from mining, dredging, dam construction or land-use change, can be judged. Comparable investigations along the Arvand River in Iran, the Pashur River in Bangladesh, the Ravi River in Pakistan and the coastal wetlands of southern Taiwan have revealed that fluvial radioactivity can vary enormously with geology, and in some industrialized estuaries technogenic nuclides from mining discharges or phosphogypsum releases dominate the picture. Against that backdrop, the low uranium and thorium readings in this Nigerian system signal an environment whose radiological profile remains essentially natural.

The study also contributes methodological value to the radiological sciences. Gamma spectrometry with sodium iodide detectors requires meticulous attention to detection efficiency, coincidence summing effects and source-to-detector geometry, and the growing literature on detector calibration offers practical guidance for laboratories working with modest infrastructure. By demonstrating that credible, standards-aligned hazard assessments can be produced with such instrumentation, the research lowers the barrier for similar monitoring programs in other data-poor tropical basins. The authors acknowledge research assistants Miss Daud Ajarat Olaide and Mr. Adeyeni Tunmise Afolabi for their contributions during the field study, and the work was funded by the Centre for Advanced Materials Research and Development, highlighting the role of institutionally supported, locally grounded science in filling global environmental data gaps.

Looking ahead, the researchers position their dataset as a foundation for longitudinal monitoring. Natural radioactivity is not static: sediments are eroded, redeposited and chemically transformed, and the same estuary measured after a decade of accelerated development could present a different signature. The measured values, now archived in the peer-reviewed literature and available upon reasonable request, give regulators in Osun State and beyond a defensible pre-disturbance benchmark. They also give residents a rare piece of quantified good news: the muds beneath their river, far from being a hidden radiological hazard, are among the quieter sediments on the planet, holding only a whisper of the uranium and thorium that Earth’s crust normally carries, and a dose burden that any international safety authority would judge unremarkable.

Subject of Research: Measurement of natural radionuclide activity concentrations and radiological hazard indices in sediments of a tropical river estuarine system

Article Title: Sediment-associated natural radionuclide and radiological risk indicators in a tropical river estuarine system

Article References: Ben-Festus, B. N., & Ben, F. (2026). Sediment-associated natural radionuclide and radiological risk indicators in a tropical river estuarine system. Environmental Monitoring and Assessment, 198(10), Article 1069. https://doi.org/10.1007/s10661-026-15895-w

Image Credits: AI Generated

DOI: 10.1007/s10661-026-15895-w

Keywords: natural radionuclides, gamma spectrometry, estuarine sediments, radiological risk, potassium-40, uranium-238, thorium-232, tropical river, environmental monitoring, radiation dose, Nigeria, radium equivalent activity