Local Contamination Research Articles

An assessment of total coliforms and associated thresholds as water quality indicators using a large Ontario private drinking water well dataset

A spatiotemporally static total coliform (TC) concentration threshold of five colony-forming units (CFU) per 100 mL is used in Ontario to determine whether well water is of acceptable quality for drinking. The current study sought to assess the role of TC and associated thresholds as microbial water quality parameters as the authors hypothesized that, since static TC thresholds are not evidence-based, they may not be appropriate for all well water consumers. A dataset containing the microbial water quality information of 795,023 samples (including TC and Escherichia coli (E. coli) counts) collected from 253,136 private wells in Ontario between 2010 and 2017 was used. To accurately assess the relationship between E. coli and non-E. coli TC, “non-E. coli coliform” (NEC) counts were calculated from microbial water quality data and replaced TC throughout analyses. This study analysed NEC and E. coli detection rates to determine differences between the two, and NEC:E. coli concentration ratios to assess links, if any, between NEC and E. coli contamination. Study findings suggest that spatiotemporally static NEC thresholds are not appropriate because seasonal, spatial, and well-specific susceptibility factors are associated with distinct contamination trends. For example, NEC detection rates exhibited bimodality, with summer (29.4 %) and autumn (30.2 %) detection rates being significantly higher (p < 0.05) than winter (21.9 %) and spring (19.9 %). E. coli detection rates also varied seasonally, but peaked in summer rather than autumn. As such, it is recommended that these factors be considered during the development of private well water guidelines and that static thresholds be avoided. Furthermore, the authors propose that, because NEC:E. coli concentration ratios change in the context of the aforementioned factors, they may have a role in inferring groundwater contamination mechanisms, with high ratios being associated with generalized aquifer contamination mechanisms and low ratios with localized contamination mechanisms.

Genetic characterization of Toxoplasma gondii in meat-producing animals in Iran

BackgroundThe consumption of uncooked or undercooked food from infected intermediate hosts can result in Toxoplasma gondii infection in humans. However, few studies have investigated the genetic diversity of this protozoan parasite in Iran. The aim of the present study was to genetically characterize isolates of T. gondii from intermediate host animals in Mazandaran Province, Iran.MethodsBlood and heart tissue samples were collected from 204 ruminants, and brain tissue was collected from 335 birds. The prevalence of T. gondii infection in these samples was determined serologically using the modified agglutination test and by conventional PCR assays. Those PCR samples positive for T. gondii DNA and 13 DNA samples extracted from aborted fetuses in a previous study were genotyped with 12 genetic markers using the multilocus-nested PCR-restriction fragment length polymorphism (Mn-PCR–RFLP) technique.ResultsAntibodies for parasites were found in 35.7% of the ruminant (39.1% of sheep and 26.4% of goats) samples and in 51.3% of the bird (100% of geese, 52.3% of free-range chickens and 46% of ducks) samples. Molecular detection by PCR of the repetitive 529-bp DNA fragment revealed contamination of 13.2% of ruminant (14.6% of sheep and 9.4% of goats) samples and of 9.6% of bird (11.1% of chickens, 5.7% of ducks and 0% of geese samples). The results from 30 DNA samples revealed five ToxoDB (genome database for the genus Toxoplasma) PCR–RFLP genotypes, including #1 (Type II), #2 (Type III), #10 (Type I), #27 and #48, with genotype #1 the most predominant.ConclusionsAs evidenced by the results of this study, ruminants and birds are infected with T. gondii in the region, suggesting that they are likely to be involved in the transmission of T. gondii to humans through meat consumption. The identification of different genotypes may suggest a higher genetic diversity of this parasite in Mazandaran, reflecting local environmental contamination. These results have important public health implications for the prevention and control strategies of infection.Graphical

Excess Cr and Ni in top soil: Comparing the effect of geology, diffuse contamination, and biogenic influence

Chromium (Cr) and nickel (Ni) are among the elements that are most mined, processed and used in modern industry and society. A realistic estimate of the diffuse contamination that has left a footprint on soil during the last 200 years by worldwide industrialization requires recognition and assessment of the dominant natural and anthropogenic sources. The relations between geogenic, anthropogenic, and biogenic Cr and Ni sources are estimated from eight large-scale geochemical surveys, by comparing the cumulative distribution functions (CDF) of the elements in top- and sub soil using cumulative probability (CP) diagrams. This method makes it possible to estimate the effect of long-term diffuse contamination on soil without monitoring. The method offers a cheaper and more reliable method for estimating diffuse contamination at the continental to regional scale than classical monitoring methods. The impact of diffuse contamination can be recognized at the low-concentration end while strong local contamination is shown as a distort at the high-concentration end of the distribution. Chromium, due to its structural similarities with essential nutrients, shows a clear biological signal in the CP-diagram. The bio-adjustment of Cr and Ni limits the accuracy of the diffuse contamination estimates. Combining CDF analysis with spatial mapping provides insight into the dominant contamination processes that distort the top soil CDF relative to the sub soil CDF. For both elements, a diffuse contamination signal of <1 mg/kg is obtained for soils at the European scale. Agricultural soil is affected by contamination from farming practices and shows higher excess Cr and Ni in top soil than forest soil. Although the world has faced several centuries of industrial development and Cr and Ni are used “everywhere”, this is not reflected in surface soil at the continental to regional scale. The regional distribution of both elements is dominated by natural sources and processes.

Blood mercury concentrations in four sympatric gull species from South Western France: Insights from stable isotopes and biologging

Mercury (Hg) is a toxic trace element widely distributed in the environment, which particularly accumulates in top predators, including seabirds. Among seabirds, large gulls (Larus sp) are generalist feeders, foraging in both terrestrial and marine habitats, making them relevant bioindicators of local coastal Hg contamination. In the present study, we reported blood Hg concentrations in adults and chicks of four different gull species breeding on the French Atlantic coast: the European herring gull (Larus argentatus), the Lesser black-backed gull (L. fuscus), the Great black-backed gull (L. marinus) and the Yellow-legged gull (L. michahellis). We also investigated the potential role of foraging ecology in shaping Hg contamination across species, using the unique combination of three dietary tracers (carbon, nitrogen and sulfur stable isotopes) and biologging (GPS tracking). A high concentration of Hg was associated with high trophic position and a marine diet in gulls, which was corroborated by birds’ space use strategy during foraging trips. Adults of all four species reached Hg concentrations above reported toxicity thresholds. Specifically, adults of Great black-backed gulls had a high trophic marine specialized diet and significantly higher Hg concentrations than the three other species. Blood Hg was 4–7 times higher in adults than in chicks, although chicks of all species received mainly marine and high trophic position prey, which is expected to be the cause of blood Hg concentrations of toxic concern. By using both stable isotopes and GPS tracking, the present study provides compelling insights on the main feeding habits driving Hg contamination in a seabird assemblage feeding in complex coastal environments.

Spatial Variations of the Activity of 137Cs and the Contents of Heavy Metals and Petroleum Products in the Polluted Soils of the City of Elektrostal

The levels of specific activity of 137Cs and the contents of mobile forms (1 M ammonium acetate extraction) of heavy metals (Zn, Cu, Ni, Co, Cr, Pb) and petroleum products were studied in the upper soil horizon of urban landscapes of the city of Elektrostal under conditions of local radioactive and chemical contamination were studied. In the soils within a short radius (0–100 m) around the heavy engineering plant, the specific activity of 137Cs and the contents of mobile forms of Pb, Cu, and Zn were increased. The lognormal distribution law of 137Cs was found in the upper (0–10 cm) soil layer; five years after the radiation accident, the specific activity of 137Cs varied from 6 to 4238 Bq/kg. The coefficients of variation increased with an increase in the degree of soil contamination in the following sequence: Co < Ni < petroleum products < Cr < 137Cs < Zn < Pb < Cu ranging from 50 to 435%. Statistically significant direct correlation was found between the specific activity of 137Cs and the contents of mobile forms of Pb, Cu, and Zn in the upper horizon of urban soils, and this fact indicated the spatial conjugacy of local spots of radioactive and polymetallic contamination in the studied area. It was shown that the specific activity of 137Cs, as well as the content of heavy metals and petroleum products in the upper layer (0–10 cm) of the soils disturbed in the course of decontamination, earthwork and reclamation is reduced.

Applications of Mercury Stable Isotopes in Environmental Forensics

Mercury is a globally distributed toxic trace metal, which can travel long distances in the atmosphere and bioaccumulate to elevated levels in ecosystem food webs. Since 2013, various parts of the mercury life cycle, including the production, use, emissions, releases, as well as the environmental and ecosystem fate, have been governed via the global treaty on mercury, the Minamata Convention of Mercury. The convention also calls attention to the application of mercury stable isotopes for distinguishing between various mercury sources in environmental media and for identifying sources, which require targeted risk management. Here, we introduce ways in which mercury stable isotopes can be applied in the field of environmental forensics to identify sources responsible for local contamination and global cycling that require international governance. This review is divided into: 1) the general overview on the mercury speciation and cycling, 2) the nomenclature of mercury stable isotope systems, and 3) the introduction of case studies that have successfully utilized mercury isotopes to interpret legacy and recent mercury sources in atmospheric and freshwater environments. We conclude the review by making specific recommendations as to how mercury stable isotopes can be better utilized in the field of local and global environmental forensics. These recommendations include the development of comprehensive anthropogenic mercury source inventories and isotopic-based evidence on the transboundary transport of mercury.

Electrolytic cleaning study of cold rolled steel using scanning Kelvin probe

ABSTRACT Oils and iron fines deposit on carbon steel during cold rolling and are removed by an electrolytic cleaning line (ECL). Sometimes localized contamination is observed on the ECL samples. No reliable tests are available for on-line measurement and the off-line tests demand samples with a large surface area. SKP addresses this issue effectively. SKP shows ∼390 mV potential difference between the clean and the uncleaned surface, with the cleaned surface potential being more positive. This indicates that the oil on the steel acts as a Lewis base, whereas the steel surface acts as a Lewis acid. Hence, the potential of the sample increases after cleaning. FTIR confirmed the absence of oil peaks on the cleaned samples. Deposition of an optimum thickness of the silicate layer is another important aspect of the ECL. It was measured by AES which displayed 2.3 nm of the silicate layer deposited on the cleaned steel surface.

Using epibenthic fauna as biomonitors of local marine contamination adjacent to McMurdo Station, Antarctica

Ten benthic fauna taxa in a polluted marine area adjacent to McMurdo Station, Antarctica were deemed to be potential biomonitors because PCBs, DDTs, PAHs, copper, lead and/or zinc in their tissues were significantly higher than in tissues of taxa living in reference areas (p < 0.05). Concentrations of PCBs and DDT were highest in Trematomus (fish). Total PAH concentrations were highest in Alcyonium antarcticum (soft coral), Isotealia antarctica (anemone) and L. elliptica. Copper and lead concentrations were highest in Laternula elliptica (bivalve) and Flabegraviera mundata (polychaete), and lowest in Trematomus and Parbolasia corrugatus (nemertean). However, copper concentrations were even higher in the asteroids Perknaster fuscus antarcticus, Odontaster validus and Psilaster charcoti. Bioaccumulation factors for different species were highest for PCBs and DDT, and lowest for lead. Bioaccumulation of some contaminants are likely prevalent in benthic taxa at McMurdo Station, but concentrations are usually low relative to human consumption standards.

Marine plastics in Mediterranean islands: Evaluating the distribution and composition of plastic pollution in the surface waters along four islands of the Western Sea Basin

To study the spatial distribution of sea surface plastics in marine protected and non-protected areas, 65 sea surface trawls were carried out using a Hydro-bios manta net coupled with a 335-μm mesh. A total of 19 sampling sites along the coastal waters of Mallorca, the “Parque Nacional Marítimo-Terrestre del Archipiélago de Cabrera” and Menorca in the Balearic Islands as well as along coastal waters of The Natural Park of Columbretes Islands (NW Mediterranean Sea) were sampled.A total of 10,637 plastic items were identified and a subset of these items was categorized by shape, color, size and polymer composition. Plastic particles were found at each sampling site and in all samples. No microscale nor mesoscale variability in floating marine plastics abundance (particles/m2) was encountered throughout the study area where similar values were found in protected areas with no local land-based contamination sources, such as Columbretes [0.04 (±0.03) particles/m2], and in high anthropized areas, such as the island of Mallorca [0.04 (±0.07) particles/m2]. However, differences were found in characteristics of plastic items (shape, polymer, and size range), with the protected area of Columbretes characterized by the presence of the highest density of very small plastic items composed mainly of fragments (93%). Quantified plastics from the marine environment were composed mainly of polyethylene (PE, 63.3%), polypropylene (PP; 24.9%), polycarbonate (PC; 4.6%) and polystyrene (PS, 3.3%). The polymer composition showed a homogenous composition between islands and differences were detected only amongst Columbretes and the other islands.Results from this study provide further evidence of the ubiquity of plastics in the marine environment and highlight that remote and protected areas, such as Columbretes, are not exempt from plastic pollution, but receptor areas for small and aged floating plastics composed mainly by fragments, which might have potentially harmful effects on protected ecosystems.

Organophosphate esters in Arctic air from 2011 to 2019: Concentrations, temporal trends, and potential sources

Concentrations of seven organophosphate ethers (OPEs) were quantified in passive air samples deployed for eight consecutive one-year periods from August 2011 to August 2019 at seven sampling sites in the area of Ny-Ålesund, Svalbard, Arctic. Non-chlorinated and chlorinated OPEs were approximately equally abundant and the mean atmospheric concentration for the sum of OPEs was around 300 pg/m3. Levels of OPEs were two orders of magnitude higher than those of polybrominated diphenyl ethers in the sampling regions, likely a result of efficient long-range transport and higher environmental release rates. For the two most abundant compounds, tris(2-chloroethyl) phosphate and tris-n-butyl phosphate, increasing temporal trends in atmospheric concentrations were observed, with estimated doubling times of 2.9 and 4.2 years, respectively. Slightly elevated OPE levels at two sampling sites in the vicinity of a research station and the local airport suggest the possible influence of local contamination sources. Re-volatilization from glaciers may also influence levels of OPE in the Arctic atmosphere.

The impact assessment of desalination plant discharges on heavy metal pollution in the coastal sediments of the Persian Gulf

In recent decades the development of desalination plants (DPs) for desalination of seawater has increased dramatically, while little attention has been paid to the effects of this activity on the accumulation of heavy metals (HMs) in the sediments of affected ecosystems. The present study was implemented to evaluate (1) heavy metal accumulation in sediments impacted by DPs discharges, (2) spatial and temporal changes of HMs and the contamination degree by different types of pollution indexes (single and integrated indices), and (3) ecological risk assessment of cadmium (Cd), lead (Pb), zinc (Zn) and copper (Cu) in sediments affected by DPs discharges. A total of 288 sediment samples were collected seasonally at 24 stations from November 2019 to October 2020. Analysis of HMs concentrations in sediments near the desalination plant discharge provided evidence of local contamination. Maximum concentration of Cu and Pb elements were found in sediments near the desalination plant discharge point. Hierarchical cluster analysis revealed clear segregation of stations impacted by desalination plant discharges and away from discharges. The values of PLI index in sediments of all sampling stations were < 1, indicating that there was no metal pollution by this index. The potential ecological risk index (PERI) ranged from 5.33 ± 0.51 to 11.81 ± 4.98 in sampling sediments and were classified as “low potential ecological risk”. These results demonstrate that the DPs discharge increased HMs concentrations in the sediments in close proximity to outlets. The necessary and practical regulations and policies regarding the rejection of the DPs discharge and disposal of chemical compounds must be implemented and enforced.

Frequency and characteristics of bacterial and viral low-grade infections of the intervertebral discs: a prospective, observational study

Study designMonocentric, prospective, observational study.ObjectiveThe clinical relevance of bacterial colonization of intervertebral discs is controversial. This study aimed to determine a possible relationship between bacterial and viral colonization and low-grade infection of the discs.MethodsWe investigated 447 disc samples from 392 patients. Microbiological culture was used to examine the samples for bacterial growth, polymerase chain reaction (PCR) was used for detection of herpes simplex virus types 1 and 2 (HSV-1, HSV-2) and Cytomegalovirus (CMV), and histopathological analysis was used to detect signs of inflammation. The results were compared between subgroups organized according to gender, age, location of the samples, surgical approach, preoperative C-reactive protein (CRP), preoperative and 6 months postoperative Oswestry Disability Index (ODI) and Neck Disability Index (NDI), and Modic changes (MC) of the corresponding endplates. Also, we assessed the occurrence of postoperative infections within 6 months.ResultsMicrobiological culture was positive in 38.78% of the analyzed intervertebral discs. Altogether, 180 bacteria were isolated. Coagulase-negative staphylococci (CONS) (23.41%) and Cutibacterium acnes (18.05%) were the most frequently detected microorganisms. None of HSV-1, HSV-2, or CMV were detected. Male patients (p = 0.00036) and cervical segments (p = 0.00001) showed higher rates of positive culture results. Ventral surgical approaches ( p < 0.001) and Type 2 MC (p = 0.0127) were significantly associated with a positive microbiological result ( p< 0.001). Neither pre- nor postoperative ODI and NDI are associated with positive culture results. In 4 (1.02%) patients, postoperative spondylodiscitis occurred.ConclusionsWith 447 segments from 392 patients, we present one of the largest studies to date. While disc degeneration caused by HSV-1, HSV-2, and CMV seems unlikely, we found positive microbiological culture results in 38.78% of all discs. The role of local skin flora and sample contamination should be the focus of further investigations.Level of EvidenceIII.Trial registration: The study was registered at ClinicalTrials.gov (ID: NCT04712487, https://www.clinicaltrials.gov/ct2/show/study/NCT04712487).

Heavy metals and metalloid levels in the tissues of yellow-legged gulls (Larus michahellis) from Spain: sex, age, and geographical location differences

In the present study, mercury (Hg), cadmium (Cd), lead (Pb), selenium (Se), and arsenic (As) were measured in liver, kidney, and feathers of adult, juvenile, and chick seagulls (Larus michahellis) collected from the northwest of Spain. Age, sex, and the geographical location of samples were considered variables that can influence metal bioaccumulation, for which concentrations were determined by means of ICP-MS. The mean concentrations (dry weight) found in seagulls were 7.01 ± 0.37 mg Hg/kg, 22.82 ± 2.83 mg Cd/kg, 7.36 ± 1.36 mg Pb/kg, 18.64 ± 0.63 mg Se/kg, and 10.64 ± 0.59 mg As/kg. Regarding the different factors analyzed, Hg was the only metal showing sex-related differences, being significantly higher (p < 0.05) the concentrations found in feathers of males (1.26 ± 0.12 mg/kg) than those in females (0.99 ± 0.11 mg/kg). A highly significant (p < 0.01) increase in levels of some metals was found in liver related to the increase of age: Hg (adults (A) 3.33 ± 0.22 mg/kg vs chicks (C) 1.76 ± 0.28 mg/kg), Cd (A 4.74 ± 0.62 mg/kg vs C 1.79 ± 0.2), Pb (A 0.65 ± 0.12 mg/kg vs juveniles 0.4 ± 0.11 mg/kg), and Se (A 7.56 ± 0.43 mg/kg vs C 5.24 ± 0.53 mg/kg). Positive correlations between Cd-Hg and Se–Hg were found in liver (p < 0.001), kidney (p < 0.001), and feathers (p < 0.05 and p < 0.001, respectively). The associations found may reflect antagonistic interactions between Se and Cd on Hg toxicity. The results suggest that L. michahellis can reveal local contamination around the foraging and breeding sites and can be a very useful monitoring instrument for assessing heavy metal contamination and sentinel species of environmental health.

Walking survey technique for ambient gamma dose rate measurement established in Fukushima Medical University

ABSTRACT This study aimed to establish a walking survey technique for rapidly determining the distribution of the ambient gamma dose rate. The measurement system consists of a scintillation spectrometer and a Global Positioning System receiver, which are controlled using a laptop. In addition to locality information, the ambient gamma dose rates were measured continuously and corrected based on shielding by the measurer body. The measurement interval was optimized at 12 s based on the locality resolution and fluctuations of the measured dose rates. A comparison was also made between the dose rate distribution maps depicted by the walking survey technique and spot measurements at fixed points. Based on the measurement data selected for the comparison, it was found that the values of 80% of the data obtained using the walking survey technique deviated within ±20% relative to those obtained by spot measurements. Compared to the spot measurements, the time taken to depict the map was reduced to one-fifth, and the localized contamination points could be depicted.

ENVIRONMENTAL LEVELS OF RADIOCARBON IN LUND, SWEDEN, PRIOR TO THE START OF THE EUROPEAN SPALLATION SOURCE

ABSTRACTThe European Spallation Source (ESS) is a neutron-based research facility under construction in Lund in southern Sweden. The spallation reactions will generate not only the desired neutrons, but also many radioactive by-products, including 14C. As part of the licensing process, and as recommended by the IAEA, various preoperational studies are being carried out, including mapping the “zero-point” radiation environment around the site. As the city of Lund hosts several facilities using 14C-labeled substances, and since temporary and local 14C contamination have been observed in the past, 14C mapping is an important part of these baseline assessments. We here present a summary of 14C levels in various terrestrial environmental samples in Lund and in southern Sweden during the years 2012 to 2020. These environmental F14C do not display significantly elevated levels compared to sites located remote from Lund. We also describe a local 14C contamination event that was detected at the Lund Radiocarbon Dating Laboratory in 2009. Horse-chestnut leaves collected close to the laboratory exhibited F14C values of up to ∼25% above the clean air background. Elevated values of F14C were also found in a short tree-ring series, especially in 2007. The source of this contamination was identified and successfully removed.

Local melt contamination and global climate impact: Dating the emplacement of Karoo LIP sills into organic-rich shale

The emplacement of Large Igneous Provinces (LIPs) is commonly correlated with global climate change, and environmental and biological crises. To establish this complex causative link, chemical proxies from marine sedimentary sections must be temporally tied to LIP activity through high-precision geochronology. The temporal link is often ambiguous, especially as periods of environmental change are commonly shorter than the full duration of magmatic and volcanic activity in a LIP. Most importantly, temporal relations need to be established through precise and accurate U-Pb geochronology; however, mafic rocks are often undersaturated in zircon or baddeleyite. New U-Pb age determinations of pegmatitic pods from Karoo LIP dolerite sills into the Ecca Group of the Karoo Basin yield single crystal dates with uncertainties below 50 ka, which allow for a new, detailed assessment of this intrusive event. These samples yield complicated age spectra and Hf geochemistry, which indicate that localized assimilation of sedimentary rocks enabled zircon saturation within these mafic melts. Zircon crystallization age interpretations from these data indicate that sill emplacement within the Ecca Group was coeval across the basin within uncertainty of U-Pb dating, and therefore represents a period of particularly high magma flux. Since the Ecca Group is locally exceptionally rich in organic matter, the widespread and rapid sill-related contact metamorphism generated a significant volume of thermogenic volatiles. Given the temporal overlap of the emplacement of sills between 183.147 ± 0.059 Ma and 183.187 ± 0.133 Ma and the timing of the global Toarcian Oceanic Anoxic Event (TOAE), our data support a causal link between this discrete period of high flux emplacement of Karoo sills into the Ecca Group and the global climate change that took place during the Early Jurassic.

Mercury concentrations in coastal Elasmobranchs (Hypanus guttatus and Rhizoprionodon porosus) and human exposure in Pernambuco, Northeastern Brazil.

Elasmobranchs are long-lived predatory fish that show high Hg concentrations generally reflecting environmental levels, notwithstanding they are widely consumed in Brazil increasing Hg exposure to humans. This study reports on Hg concentrations in largely consumed sharks (Rhizoprionodon porosus) and rays (Hypanus guttatus) from the Pernambuco coast, NE Brazil and the risk associated with their consumption. Muscle tissue concentrations of Hg in H. guttatus and R. porosus varied from 40 to 1,020 ng.g-1 w.w. (median = 125; mean = 124 ± 48 ng.g-1 w.w.) in sharks and from 129 to 2,130 ng.g-1 w.w. (median = 976; mean = 919 ± 139 ng.g-1 w.w.) in rays. Concentrations of Hg positively correlated with size in sharks, but not in rays. Concentrations reflect the local environmental contamination of a large urban center and industrial park concentrated in a short extension of mangrove-dominated coastline (50 km) and are higher compared to other Brazilian sites where Hg concentrations in these species have been reported. Sharks had a risk coefficient (HQ) range of 0.04 to 1.1, not surpassing the reference level of exposure. On the other hand, rays' HQ ranged from 0.14 to 2.3, and exceeds the reference level of exposure and suggests adverse effects to consumers.

Distribution and provenance of heavy metals in sediments of the Vrbas River, Bosnia and Herzegovina

Heavy metals are naturally occurring elements, but they are regarded as significant environmental pollutants due to their high density and high toxicity even at low concentrations. The aim of this paper is the evaluation of the pollution level of heavy metals in the river and riverbank sediments, as well as the estimation of their origin and spatial differences along the course of the Vrbas River through Banja Luka. The concentrations of metals have been assessed using the Inductively coupled plasma ? optical emission spectrometry and Advanced mercury analyzer for mercury determination. The anthropogenic impact on heavy metal concentration in sediments was estimated by the calculating of pollution indices: geoaccumulation index (Igeo), contamination factor (Cf), pollution load index (PLI) and potential ecological risk index (Er). Obtained results indicate that there is no statistically significant spatial difference in metal concentration, indicating that heavy metals in sediments have a constant source. The anthropogenic impact expressed by the values of pollution indices showed that sites are generally uncontaminated by Co, Cr and V and moderately contaminated by Zn, Cu and Ni. On the contrary, lead, mercury and cadmium pose the highest ecological risk. The anthropogenic source of Pb, Hg and Cd is industry, municipal waste and the combustion of fossil fuels. The obtained results demonstrate the high ecological risk and the need for environmental monitoring, with the aim to support an efficient strategy to reduce local pollution and contamination of the investigated system.

Оценка радиационной обстановки в районе расположения АО «ГНЦ НИИАР» до начала эксплуатации ИЯУ МБИР. Часть 2. Водные экосистемы

The analysis of the radiation survey results of freshwater ecosystems of three rivers and the Cheremshansky Bay of the Kuibyshev Reservoir in the vicinity of State Scientific Centre “Research Institute of Atomic Reactors” (SSC RIAR, Institute) before the start of the MBIR fast neutron reactor operation was carried out. The content of natural (K-40, Ra-226, Th-232) and artificial (Sr-90, Cs-137) radionuclides in the main components of freshwater ecosystems: surface and underground waters, bottom sediments, floodplain soils and vegetation, and ichthyofauna was estimated. It has been shown that the specific activity of Cs-137 in the waste water of industrial storm sewerage (PLK-1) of the enterprise is 10-70, Sr-90 2-10 times higher compared to the surface waters of reservoirs of its zone of influence. This is due to the removal of radionuclides from the site of local contamination in the sanitary protection zone of SSC RIAR. In Cheremshansky Bay, downstream, the concentration of radioisotopes decreases by 8-50 times due to dilution processes and their sorption by bottom sediments and hydrobionts. It is noted that the sorption properties of bottom sediments are determined by the presence of organic compounds in their composition. The multidirectional nature of the accumulation of artificial radionuclides in floodplain soils and plants is shown. In some cases, it is determined by the distance from the source of gas-aerosol emissions of radioisotopes and affects the secondary pollution of freshwater ecosystems. Monitoring data demonstrate a stable decrease in the content of artificial radionuclides in surface waters. In Cheremshansky Bay in 2005-2020 for Cs-137 it was 5 times, for Sr-90 it was 3 times. It has been noted that in recent years, the specific activity of artificial radionuclides in sewage of SSC RIAR, surface and underground waters, as well as fish in the zone of enterprise influence is at the level of the regional background and is 1-3 orders of magnitude lower than the current radiological standards. The importance of further radioecological monitoring of freshwater ecosystems in the SSC RIAR location area after the commissioning of the MBIR for assessing the impact of the new reactor on humans and the environment is shown.

Difficult to treat esophageal perforation after endoscopic balloon dilation for stenosis due to endoscopic submucosal dissection followed by chemoradiotherapy: A case report.

Introduction and importanceThere is no clear consensus on a specific treatment for esophageal perforation. The surgical approach is deemed necessary for local severe infection and pleural contamination requiring debridement.Presentations of caseWe have reported herein the case of a patient with esophageal perforation with severe mediastinal and thoracic abscess after endoscopic balloon dilation for stenosis due to endoscopic submucosal dissection and chemoradiotherapy. A surgical approach with primary closure was performed, but not found effective; while conservative treatment with mediastinal drainage via posterior neck and recovery of nutritional status was found to be effective. For the recovery of nutritional status, enteral nutrition was assessed using a polymeric formula through a percutaneous endoscopic gastrojejunostomy tube.DiscussionEsophageal perforation is a life-threatening condition. Iatrogenic injuries are the frequent cause of esophageal perforation. For esophageal perforation, not only surgical interventions but also conservative treatments including various endoscopic approaches have been performed. If the inflammation is not localized, surgical intervention is often needed; however, if the patient's general condition is stable, conservative treatment with drainage, antibiotics, and nutritional management may be considered, even in cases of esophageal perforation.ConclusionsEsophageal perforation with a large perforation site with widespread inflammation can be improved with proper thoracic and mediastinal drainage and adequate nutrition support if the patient's condition is mild.