Determination of radioactivity and heavy metals of Bakirçay river in Western Turkey

Oral and dermal exposure to natural radionuclides and heavy metals in water and sediments of Nile River, Qena, southern Egypt

This study assessed the levels of natural radionuclides (226Ra, 232Th, and 40K) and heavy metals (Hg, Fe, Cr, As, Zn, Cu, Cd, and Pb) in surface water and sediment samples from the Nile River in Qena Governorate, southern Egypt, using a gamma-ray spectrometer, 3" NaI (Tl) scintillation detector coupled with 1024 multi-channel analyzer, and an atomic absorption spectrometer. In surface water and sediments, the average activity concentrations of natural radionuclides were 40K (4.73 Bq L-1; 395.76 Bq kg-1) > 226Ra (0.41 Bq L-1; 18.14 Bq kg-1) > 232Th (0.30 Bq L-1; 17.98 Bq kg-1). The average heavy metal concentrations in surface water in µg L-1 were Fe (121.0) > Zn (33.80) > Cr (28.0) > Cu (8.62) > Pb (8.35) > As (1.19) > Hg (0.81) > Cd (0.12). In Nile sediments the concentrations in mg kg-1 were Fe (1670.0) > Zn (207.0) > Cr (29.40) > Cu (16.20) > Pb (4.32) > Hg (0.41) > Cd (0.31) > As (0.14). The heavy metal evaluation index (HMEI) calculations for water samples revealed that 31% of the samples were suitable for domestic use, while 69% were not. The geo-accumulation index, enrichment factor, and ecological risk factor for sediments were estimated, showing extreme enrichment for Hg and Zn with high ecological risk for Hg. Health risks for adults were evaluated due to oral and dermal exposure to Nile surface water and sediments from the study area, indicating minimal radiological risks and potential carcinogenic and non-carcinogenic risks from the metals.

Understanding water characteristics and arsenic contamination of Lower Bakırçay Basin (LBB) and its coastal wetland (Western Turkiye): from Bergama (Pergamum) to Çandarlı (Elaia) by hydrogeochemical tools and stable isotope signatures

Bakırçay Basin is one of the largest and most productive basins in Turkey in terms of geothermal energy, history, mining, agriculture, and tourism. In this study, the lower part of the Bakırçay Basin was extensively examined using hydrogeochemical tools, encompassing 27 different water sample points in the basin, in alignment with the United Nations' 2030 sustainable development goals that focus on access to safe drinking water for all and climate action for carbon emissions. From the higher zones of the basin towards the coastal wetland, EC values increase from 212 to 26500 µS/cm. Again in the same direction, water types are Ca-Mg-HCO3 in hilly areas and Na-Cl at the coastal wetland. Salt marshes, which are the silent heroes of carbon sequestration, are the most important element of the Bakırçay coastal wetland. Irrigation water evaluation has also been made for agriculture, which is widespread in the basin. Except for the salty waters in the wetland, waters are suitable for irrigation. A contamination investigation was conducted in the waters with the aim of clean drinking water. As and Mn contamination, which exceeds the standard values, has been detected in the Bakırçay river and its tributaries, especially from the mining sites in LBB. The arsenic content of water in the study area varies between 2 and 62.2 ppb. Additionally, the study identified As(III) species, which is 60 times more toxic than As(V), in the study area. Stable isotope values (δ18O and δD) of waters in the basin are from - 6.66 to 1.43‰ and - 36.4 to 5.8‰, respectively, and all waters are of meteoric origin. It is essential to emphasize the importance of controlling mining activities in the basin, halting the construction of the port that will destroy the carbon sequestration coastal wetland, and instead, transforming it into a recreation area, the significance of which is now understood during the COVID-19 pandemic.

Distribution of heavy metals and radionuclides in the sediments and their environmental impacts in Nansha Sea area, South China Sea

Activity concentrations of radionuclides (²³⁸U, ²²⁶Ra, ²³²Th, and ⁴⁰K) in the sediments of eight sampling stations and heavy metal concentrations (Cr, Co, Ni, Cu, Zn, As, Cd, and Pb) in the sediments of two long cores from Nansha Sea area were obtained by high-purity germanium spectroscopy and inductively coupled plasma atomic emission spectrometry. In a correlation analysis between the radionuclides and heavy metals, ²³²Th was positively correlated with As and Pb. ²³⁸U demonstrated a significant positive correlation with Co, Ni, Cu, Zn, and Cd. ⁴⁰K was positively correlated with Co, Ni, and Cu. The geo-accumulation index, pollution load index, potential ecological risk index, and multivariate statistical techniques were used to evaluate the pollution degree and possible sources of heavy metals in the sediments. An ecological risk assessment suggested that Cr, Co, Ni, Cu, Zn, Cd, and Pb were primarily derived from natural processes, while the source of As may be related to natural processes and human activities.

Determination of uranium and thorium concentrations in sediment samples by using solid state nuclear track detectors

In this study, uranium and thorium concentrations in the sediment samples collected from the Gulf of Izmit in Marmara Sea were determined using neutron radiography method and alpha-autoradiography method. Mean uranium concentrations calculated for the sediment samples collected from the boreholes S2, S3, S5, S8 and KS-2 were found to be 5.99 μg/g (3.58-8.16 μg/g), 4,59 μg/g (2.54-8.22 μg/g), 4.03 μg/g (2.13-6.9 μg/g), 3.71 μg/g (2.36-4.48 μg/g) and 2.81 μg/g (2.16-4.06 μg/g), respectively. The highest uranium concentration in all borehole samples was obtained from borehole S3 with a value of 8.22 μg/g at a depth of 77.00 m, followed by borehole S2 with a value of 8.16 μg/g at 76.95 m depth. These results also confirms the possibility of thermal sources at boreholes S2 and S3. The mean thorium concentrations in boreholes S3 and S8 were found to be 15.26 μg/g (9.60-17.49 μg/g) and 15.76 μg/g (13.89-17.37 μg/g), respectively. The highest thorium concentration in obtained samples from all boreholes was obtained in borehole S3 with a value of 17.49 μg/g at a depth of 77.00 m.

Simple and sensitive determination of radium-226 in river water by single column-chromatographic separation coupled to SF-ICP-MS analysis in medium resolution mode

This article describes a novel and simple method to measure ultra-trace ²²⁶Ra in river water samples at fg L^-1 (mBq L^-1) levels as a means for surveying ²²⁶Ra in an unintended contamination in river water. To simplify the procedure, a single column was used for separation and purification; 10 mL of AG 50W-X8 resin was packed into a 10 mL Eppendorf pipette tip, which was used as a separation column. A 500 mL sample solution was loaded, and interfering elements were removed with 80 mL 4 M HCl in 20% ethanol. Subsequently, Ra together with Ba was eluted by 20 mL 5 M HNO₃ prior to SF-ICP-MS analysis; this allows the naturally existing Ba in water samples to be employed as a yield tracer for ²²⁶Ra analysis. Using the medium mode of SF-ICP-MS, the instrumental detection limit of 380 fg L^-1 (10 mBq L^-1) was obtained. An extremely low method detection limit of 0.46 fg L^-1 (0.02 mBq L^-1) was achieved with 500-fold pre-concentration. Finally, the developed technique was applied to analyze natural water samples collected from Japanese rivers, in which the ²²⁶Ra concentrations varied in the range of 0.7-49.6 fg L^-1 (0.03-1.82 mBq L^-1).

Using magnetic susceptibility to evaluate pollution status of the sediment for a typical reservoir in northwestern China

Intensive anthropogenic activities may add to pollution risks to lakes and rivers, which can be revealed by the magnetic characteristics of sediments. The present study aims to assess the pollution status of the sediment of a typical reservoir in northwestern China by application of magnetic susceptibility. The values of magnetic susceptibility exhibited significant positive correlations with trace metals (Co, Cu, Mn, Ni, and V) and natural radionuclides (²³²Th and ⁴⁰K). Multivariate statistical analysis indicated common sources and similar deposition characteristics of magnetic particles and trace metals. It was conformed that magnetic susceptibility could be used as an indicator to identify industrial sources of trace metals, but was not suitable to indicate the traffic or natural sources. Linear regression equations between the low-frequency magnetic susceptibility and the integrated pollution index as well as annual effective dose rate indicated a potential for using magnetic susceptibility in semi-quantitative assessment of trace metal pollution and radiological hazard in sediments. A three-step procedure is proposed for the use of magnetic susceptibility in pollution monitoring, which provides a fast and effective method for estimating the pollution extent and tracing the major sources of trace metals in the sediment of lakes and rivers.

Distribution and environmental impacts of heavy metals and radioactivity in sediment and seawater samples of the Marmara Sea

In this study, the natural and anthropogenic radioactivity levels in the sediment samples collected from the Marmara Sea in Turkey were determined. The average activity concentrations (range) of (226)Ra, (238)U, (232)Th, (40)K and (137)Cs were found to be 23.8 (13.8-34.2) Bq kg(-1), 18.8 (6.4-25.9) Bq kg(-1), 23.02 (6.3-31.1) Bq kg(-1), 558.6 (378.8-693.6) Bq kg(-1) and 9.14 (4.8-16.3) Bq kg(-1), respectively. Our results showed that the average activity concentrations of (226)Ra, (238)U and (232)Th in the sediment samples were within the acceptable limits; whereas the average activity concentration of (40)K in the sediment samples was higher than the worldwide average concentration. The average radium equivalent activity, the average absorbed dose rate and the average external hazard index were calculated as 100.01 Bq kg(-1), 48.32 nGy h(-1) and 0.27, respectively. The average gross alpha and beta activity in the seawater samples were found to be 0.042 Bq L(-1) and 13.402 Bq L(-1), respectively. The gross alpha and beta activity concentrations increased with water depth in the same stations. The average heavy metal concentrations (range) in the sediment samples were 114.6 (21.6-201.7) μg g(-1) for Cr, 568.2 (190.8-1625.1) μg g(-1) for Mn, 39.3 (4.9-83.4) μg g(-1) for Cu, 85.5 (11.0-171.8) μg g(-1) for Zn, 32.9 (9.1-73.1) μg g(-1) for Pb and 49.1 (6.8-103.0) μg g(-1) for Ni. S5 station was heavily polluted by Cr, Cu, Ni and Pb. The results showed that heavy metal enrichment in sediments of the Marmara Sea was widespread.

Natural radioactivity levels of geothermal waters and their influence on soil and agricultural activities

All over the world geothermal sources are used for different purposes. The contents of these waters are important to understand positive/negative effects on human life. In this study, natural radioactivity concentrations of geothermal waters were investigated to evaluate the effect on soils and agricultural activities. Geothermal water samples were collected from the Seferihisar Geothermal Region, and the radon and radium concentrations of these waters were analysed using a collector chamber method. Also soil samples, which are irrigated with geothermal waters, were collected from the surroundings of geothermal areas, and natural radioactivity concentrations of collected samples (U, Th and K) were determined using an NaI(Tl) detector system. The activity concentrations of radon and radium were found to be 0.6-6.0 and 0.1-1.0 Bq l(-1), respectively. Generally, the obtained results are not higher compared with the geothermal waters of the world. The activity concentrations in soils were found to be in the range of 3.3-120.3 Bq kg(-1) for (226)Ra (eU), 0.3-108.5 Bq kg(-1) for (232)Th (eTh), 116.0-850.0 Bq kg(-1) for (40)K (% K).