Assessment of Be-7, Pb-210 and Po-210 Activities in Airborne Particulate Matter Over Istanbul, Türkiye

Airborne particulate matter is one of the air pollutants which can have detrimental health effects in the human body. Radionuclides adsorb onto air particles and make their way to humans primarily through inhalation. Naturally-occurring radionuclides, 210Pb and 210Po, are of notable health concern due to their relatively elevated ingestion and inhalation doses. In the current study, activity concentrations of 7Be, 210Pb and 210Po were determined in air particulate matter (PM). PM2.5 was collected on the European side, while PM10 was collected on the Anatolian side of Istanbul. Be-7, 210Pb and 210Po activities were found to be 5.17 ± 2.35, 0.96 ± 0.42; 0.25 ± 0.14 mBq m- 3 in Anatolian side, respectively. Be-7, 210Pb and 210Po activities were found to be 3.81 ± 2.27, 0.62 ± 0.29, 0.29 ± 0.26, mBq m- 3 in European side, respectively. The ratio of 210Po/210Pb was found to be higher (0.47 ± 0.31 for PM2.5 and 0.34 ± 0.27 for PM10) than the global average of 0.1. This result can be explained by the fact that Po is more volatile than Pb and enhanced in the air by the combustion process. Inhalation dose rates of 210Pb and 210Po due to PM10 exposure were calculated to be 7.70 ± 3.30 and 4.05 ± 2.31 µSv year- 1, respectively. Pb-210 bioaccessibility was assessed by the extraction of the particles in simulated lung fluids. Approximately 24.8% of inhaled 210Pb was estimated to be bioaccessible. This study suggests that 210Po and 210Pb activities are partially enhanced in the air particles in Istanbul and should be regularly monitored.

The combined effects of polyethylene microplastics and benzoanthracene on Manila clam Ruditapes philippinarum

Microplastic (MP) toxicity has recently been explored in various marine species. Along with the toxicity of plastics polymer itself, additional substances or pollutants that are absorbed onto it may also be harmful. In the present study, we investigated the combined impacts of polyethylene microplastics (PE MPs) and an organic pollutant (Benzo(a)anthracene, BaA) on Manila clam Ruditapes philippinarum during a one-week exposure. Two PE MPs concentrations (26 μg L^-1 and 260 μg L^-1) and one BaA concentration (3 μg L^-1) were tested. The clams were exposed to BaA and PE MPs either alone or in combination. BaA and PE MPs were incubated before the combined exposure. The biological effects of PE MPs and BaA on the clams were evaluated by considering several assays such as feeding rate, anti-oxidant enzyme activities, and the expression levels of stress-related genes. The feeding rate significantly decreased in individual PE MPs and individual BaA groups while it remained unchanged in combined groups. Superoxide dismutase (SOD) was the most affected among the biochemical parameters. Malondialdehyde (MDA), and glutathione peroxidase (GPx) activities were slightly affected, whereas no changes were observed in glutathione s-transferase (GST) activities. CYP1A1, CYP3A4, and HSP70 gene expressions displayed slightly significant changes. Considering all stressor groups, high PE MPs exposure (260 μg L^-1 PE MPs) more effectively altered the biological parameters in the clams compared to individual low PE MPs and BaA exposure, and their combination. The results also indicated the negligible vector role of PE MPs to transport BaA into the clam tissues.

Chronology of trace elements and radionuclides using sediment cores in Golden Horn Estuary, Sea of Marmara

Trace elements and radionuclides are substantial pollutants in marine environment since they are non-biodegradable and can be harmful even in minute concentrations. The Golden Horn estuary, where is an inlet of Bosphorus and two creeks, has been seriously polluted by untreated municipal and industrial dischargers for several decades. Since 1998, a large restoration and rehabilitation efforts have been undertaken in the estuary to mitigate the pollution. In the present study, four sediment cores were taken from the Golden Horn estuary to assess the historical accumulation of trace elements and radionuclides. Radiometric dating was implemented by ²¹⁰Pb and ¹³⁷Cs radionuclides and CRS model. Sedimentation rates were calculated in the range of 0.92-0.97 cm yr^-1 in the estuary. The distribution of radionuclides (⁴⁰K, ²²⁶Ra, and ²²⁸Ra) indicated some slight variations which ascribes to the geological characteristics of sediment along the cores. The concentrations of the anthropogenic elements were relatively higher in the intensive industrialization period. Their concentrations reduced in the latest 15-20 years thanks to the large-scale rehabilitation project in the estuary. The pollution indices, namely EF, Igeo, CF, and PLI showed that the concentrations of Cd, Cr, Cu, Pb, Sb, and Sn were above the world averages. Our results provide an insight on the long-term accumulation trends of trace element in the Golden Horn, which revealed that the estuary remains moderately polluted. We suggest that preventive countermeasures are much more important than post pollution remediation in the case of metallic pollution in the estuaries.

Microplastic inventory in sediment profile: A case study of Golden Horn Estuary, Sea of Marmara

Assessment of microplastics (MPs) in sediment cores is necessary to unveil global plastic pollution since most of the plastic litter might have been stored in sediment columns. In the current study, MPs inventory was determined in a 105 cm sediment core, collected in the Golden Horn Estuary, Sea of Marmara. Radiodating of sediment profile by using naturally occurring ²¹⁰Pb and fission product ¹³⁷Cs allowed us to couple the retrospective of global MP production to sediment MPs inventory. More than 90% of total MPs inventory was found in the deep layer of the sediment column (below 15 cm). Small MPs (20-200 μm) were more abundant than large ones (200-4000 μm). Elevated concentrations of MPs were attributed to industrial and municipal effluent of Istanbul metropolitan. On a local scale, this study suggests that the Golden Horn Estuary was polluted with MPs before the 1950s, and the abundance of MPs reached a maximum in the 1980s. We also propose on a global scale that "the missing" plastics might have been buried in deep sediment and radiodating of sediment is useful to reveal their historical input records.

Genotoxic and cytotoxic effects of polyethylene microplastics on human peripheral blood lymphocytes

Currently, we need emerging initial data regarding how plastic exposures affect cellular and molecular components and how such interactions will be crucial for human health. We aimed to determine the genotoxic and cytotoxic effects of microplastic (MPs,10-45 μm, polyethylene) on human peripheral lymphocytes by using the cytokinesis-block micronucleus cytome (CBMN) assay, which is a comprehensive method to reveal a range of mechanisms, not only diseases but also response to environmental exposures. We measured micronucleation (MN), nucleoplasmic bridge formation (NPB), and nuclear bud formation (NBUD) in human peripheral blood lymphocytes. We also measured the cytokinesis-block proliferation index (CBPI) to calculate cytostasis, which indicates cytotoxicity in lymphocytes treated with five different MPs concentrations for 48 h. Even lower concentrations of MPs increased the level of genomic instability. We found that the in vitro MP exposure significantly increased MN, NPB, and NBUD frequencies. Since we investigated the effect of larger particles relative to the lymphocytes, mechanic interaction of MPs with cells, the release of monomer and additives from MPs could be suggested as possible mechanisms accounting for increasing genomic instabilities. We did not observe a decrease in the cell proliferation index, indicating a lack of MPs' cytotoxic potential. To the best of our knowledge, our study is the first to identify MPs' genotoxic potential in human peripheral blood lymphocytes. We suggested further studies to investigate the genotoxic and cytotoxic potential of smaller plastics and the chronic effect of MP on the human population.

Impacts of elevated pCO2 on Mediterranean mussel (Mytilus galloprovincialis): Metal bioaccumulation, physiological and cellular parameters

Ocean acidification alters physiology, acid-base balance and metabolic activity in marine animals. Near future elevated pCO₂ conditions could be expected to influence the bioaccumulation of metals, feeding rate and immune parameters in marine mussels. To better understand such impairments, a series of laboratory-controlled experiment was conducted by using a model marine mussel, Mytilus galloprovincialis. The mussels were exposed to three pH conditions according to the projected CO₂ emissions in the near future (one ambient: 8.10 and two reduced: 7.80 and 7.50). At first, the bioconcentration of Ag and Cd was studied in both juvenile (2.5 cm) and adult (5.1 cm) mussels by using a highly sensitive radiotracer method (^110mAg and ¹⁰⁹Cd). The uptake and depuration kinetics were followed 21 and 30 days, respectively. The biokinetic experiments demonstrated that the effect of ocean acidification on bioconcentration was metal-specific and size-specific. The uptake, depuration and tissue distribution of ^110mAg were not affected by elevated pCO₂ in both juvenile and adult mussels, whereas ¹⁰⁹Cd uptake significantly increased with decreasing pH in juveniles but not in adults. Regardless of pH, ^110mAg accumulated more efficiently in juvenile mussels than adult mussels. After executing the biokinetic experiment, the perturbation was sustained by using the same mussels and the same experimental set-up, which enabled us to determine filtration rate, haemocyte viability, lysosomal membrane stability, circulating cell-free nucleic acids (ccf-NAs) and protein (ccf-protein) levels. The filtration rate and haemocyte viability gradually decreased by increasing pCO₂ level, whereas the lysosomal membrane stability, ccf-NAs, and ccf-protein levels remained unchanged in the mussels exposed to elevated pCO₂ for eighty-two days. This study suggests that acidified seawater partially shift metal bioaccumulation, physiological and cellular parameters in the mussel Mytilus galloprovincialis.

Effects of microplastics and mercury on manila clam Ruditapes philippinarum: Feeding rate, immunomodulation, histopathology and oxidative stress

Plastic pollution, which is one of the most important environmental problems at the present time, has been understood recently, and the effects of this pollution on ecosystem and biota are becoming a growing problem, especially in the aquatic ecosystems. Direct or indirect exposure to those particles leads to adverse effects on marine organisms. In the marine environment, plastic materials interact with other pollutants such as metals, thereby affecting the uptake levels of those pollutants in marine organisms. In the present study, the Manila clam Ruditapes philippinarum was exposed to polyethylene microbeads and mercury chloride in single, combined and incubated form at environmentally relative concentrations for one week in controlled laboratory conditions. The uptake and tissue distribution of both stressors as well as the vector role of microplastics on mercury uptake in the organisms were investigated. Filtration rates, biomarkers for immunomodulation and oxidative stress, and histological alterations were also evaluated. Microplastics were ingested by the clams, and translocated to the various tissues. However, contaminated microplastics displayed a negligible vector role in terms of mercury bioaccumulation in the clams. The single and interactive exposure of the stressors reduced the filtration rate in the clams. Both pollutants affected the immune system of the organisms. Histological alterations were determined in the gill and digestive gland tissues of the clams among the treatment groups, although oxidative stress biomarkers remained unchanged. This study suggests that the vector role of polyethylene microplastics in mercury uptake is negligible and reveals that the single and interactive one-week exposure of two pollutants induce toxicity in the manila clams.