Contamination Trends Research Articles

Machine learning analysis of 137Cs contamination of terrestrial plants after the Fukushima accident using the random forest algorithm

Radioactive contamination of terrestrial plants was extensively investigated and quantitatively modeled after the Fukushima nuclear power plant accident. This phenomenon, which is important for ecosystem functioning and protection of human health, is influenced by multiple factors, including plant species, time after the accident, and climate. Machine learning algorithms such as random forests (RF) have a record of strong performance on large multi-dimensional data sets, but, to our knowledge, combined data on post-Fukushima plant contamination with radionuclides were not yet subjected to a machine learning analysis. Here we performed such analysis on two large published data sets: (1) 137Cs activity concentrations in four common Japanese forest tree species. (2) Plant/soil 137Cs concentration ratios in multiple perennial plant species. The goal was to show the usefulness of machine learning for identifying and quantifying the main trends of 137Cs contamination in terrestrial plants. Each data set was split randomly into training and testing parts, RF was fitted and tuned on the training parts, and its performance was assessed on the testing parts by three metrics: coefficient of determination (R2), root mean squared error, and mean absolute error. Synthetic noise variables and the Boruta algorithm were used in a customized procedure to identify the most important predictor variables, which consistently outperformed random noise. Good agreement between observations and RF predictions (e.g. R2∼0.9 on testing data) was obtained on both data sets. The effects of the most important predictors (e.g. time after the accident, 137Cs land contamination level, and plant species) and interactions between them were quantified by partial dependence plots. These results of machine learning analyses of large data collections can help to complement previous modeling efforts, and to clarify the patterns of 137Cs contamination of plants after the Fukushima accident.

(Invited) Cold Plasma As a Tool for a Removal of the Harmful Contaminants

Cold atmospheric pressure plasmas (CAP) represent an emerging technology that shows an enormous potential in removal of different hazardous contaminants relevant in the fields such as food and environmental technology and medicine [1]. In principle, plasma is the fourth state of matter; it can be created by applying the gas into a strong electrical field, which leads to the ionisation, dissociation and excitation of gaseous molecules. CAP generated using only air and electricity is a strongly non-equilibrium system, exhibiting striking physical and chemical characteristics; electron temperatures exceed 30,000 K, while the temperature of neutrals remains close to room temperature [2]. As a mixture of highly reactive particles, it represents a very promising, low-cost and eco-friendly method for decontamination with negligible effect on the treated substrate.To demonstrate its potential, we present a case study based on decontamination of mycotoxins using surface barrier discharge (SBD) CAP system, working at ambient air. Mycotoxins, the secondary metabolites produced by filamentous fungi, are toxic compounds that are found on over 70 % of global food and feed crop. Although many preventive measures are carried out, the trend of mycotoxin contamination is growing and affecting the health of more than a half of the human population [3]. Therefore, the development of a new and more effective method is necessary.We demonstrated that CAP was able to reach more than 90 % reduction of the treated mycotoxins. In comparison to commercially used UV irradiation, decontamination rate of CAP was a magnitude higher [4]. Furthermore, a detailed analysis based on CAP treatment of most potent mycotoxin aflatoxin B1 (AFB1) was performed, revealing that CAP induced degradation started at C8-C9 site of AFB1 molecule, which is also responsible for its toxicity. Further degradation led to the formation of 4 most important degradation products. Toxicity tests demonstrated that CAP induced complete removal of AFB1 toxicity [5]. According to these encouraging results, it can be concluded that CAP technology can be applied as a new efficient tool for decontamination of mycotoxins and also other emerging contaminants such as pesticides, pharmaceuticals, bisphenols etc.[1] M. Moreau, N. Orange, J.-L. Brisset, Ozone: Science and Engineering 2005, 27, 469-473.[2] A. Dickenson, Y. Morabit, M. I. Hasan, J. L. Walsh, Scientific Reports 2017, 7, 14003.[3] M. Eskola, G. Kos, C. T. Elliott, J. Hajšlová, S. Mayar, R. Krska, Critical Reviews in Food Science and Nutrition 2019, 1-17.[4] N. Hojnik, M. Modic, G. Tavčar-Kalcher, J. Babič, J. L. Walsh, U. Cvelbar, Toxins 2019, 11, 219.[5] N. Hojnik, M. Modic, J. L. Walsh, D. Žigon, U. Javornik, J. Plavec, B. Žegura, M. Filipič, U. Cvelbar, Journal of Hazardous Materials 2021, 403, 123593.

Risk assessment of potentially toxic elements in stream sediments around granite quarries, barite mines, and cultivation areas, Southeastern Nigeria.

This study assessed the contamination of streams with potentially toxic elements (PTEs) in sediments around mining, quarrying, and cultivation areas in Akamkpa and environs Southeastern Nigeria. Analysis done using ICP MS technique shows that barium (Ba) and lead (Pb) recorded mean concentrations above their average shale content (ASC) in stream sediments. Chromium (Cr) exceeded Canadian Interim Sediment Quality Guideline (ISQG) and US Environmental Protection Agency (USEPA) screening benchmark value. Pb exceeded Canadian ISQG value but tallies with USEPA benchmark value. Pearson's correlation exhibited significant correlation (p < 0.01) of molybdenum (Mo) with copper (Cu) and Pb; Cu with Pb, vanadium (V), and Ba; V with Cu, Pb, iron (Fe), Ba, and beryllium (Be); and Fe with Be and V. Principal component (PC 1) consists of Pb, Mo, cobalt (Co), Cu, arsenic (As), Cr, V, and nickel (Ni) and showed significant correlation. Geo accumulation index (I-geo) values for Mo, Cu, V, Pb, Zn, Ni, Co, Mn, and Ba fall under unpolluted (0) to moderately polluted (1-2) classes. Maximum enrichment factor (EF) values show extremely high and significant enrichment of Ba and Pb in few locations. Co, Cr, Cu, Mn, and Zn possess maximum EF values classified as moderate enrichment. Ni, Mo, As, and V obtained maximum EF values classified as depleted to minimal enrichment. Modified pollution index (MPI) values showed high PTEs contamination in mostly cultivation locations. Single element potential ecological risk (EiR) mean values trend EiR (As) > EiR (Pb) > EiR (Co) > EiR (Cr) > EiR (Cu) > EiR (V) > EiR (Ni) > EiR (Zn). Comprehensive potential ecological risk (RI) shows medium risk "B" and strong risk "C" levels in few locations. The use of multiple pollution indices such as I-geo, EF, EiR, and RI in pollution assessment indicated similar trend of PTEs contamination of stream sediments. Levels of PTEs contamination are elevated in cultivation areas more than in granite quarrying and mining areas. This study serves as a benchmark for conducting suitable environmental management strategies to scientists in Nigeria and other parts of the world.

Paleotoxicity of petrogenic and pyrogenic hydrocarbon mixtures in sediment cores from the Athabasca oil sands region, Alberta (Canada)

Despite the economic benefits of the oil and gas industry in Northern Alberta, significant concerns exist regarding the impacts of increased oil production on the environment and human health. Several studies have highlighted increases in the concentrations of polycyclic aromatic compounds (PACs) and other hydrocarbons in the atmosphere, water, soil and sediments, plants, wildlife and fish in the Athabasca Oil Sands Region (AOSR) as a result of oil sands industrial activity. Sediment cores can provide information on the temporal trends of contaminants to the environment and provide important baseline information when monitoring data are absent. Here we combined analytical chemistry and a mammalian cell-based bioassay in dated lake sediment cores to assess paleotoxicity in freshwater systems in the AOSR. Sediment intervals were radiometrically dated and subsequently analysed for PACs. PAC extracts from select dated intervals were used in cell-based bioassays to evaluate their endocrine disrupting properties. We demonstrated spatial and temporal variability in the PAC composition of sediment cores around the AOSR with some of the highest concentrations of PACs detected near oil sands industrial activity north of Fort McMurray (AB) in La Saline Natural Area. Recent sediment had positive enrichment factors across most PAC analytes at this site with heavier pyrogenic compounds such as benz(a)anthracene/chrysene and benzofluoranthene/benzopyrene dominating. Our study is the first to link chemical analysis of sediment cores with biological effect assessments of endocrine activity showing feasibility of extending the usefulness of sediment cores in monitoring programs interested in complex mixture assessments. While we observed no spatial or temporal differences in ERα mediated signaling, AhR CALUX results mirrored those of the chemical analysis, demonstrating the utility of coupling biological effects assessments to historical reconstructions of contaminant inputs to the natural environment.

Key factors influencing metal concentrations in sediments along Western European Rivers: A long-term monitoring study (1945–2020)

Since 1945, a large amount of heterogeneous data has been acquired to survey river sediment quality, especially concerning regulatory metals such as Cd, Cr, Cu, Hg, Ni, Pb, and Zn. Large-scale syntheses are critical to assess the effectiveness of public regulations and the resiliency of the river systems. Accordingly, this data synthesis proposes a first attempt to decipher spatio-temporal trends of metal contamination along seven major continental rivers in Western Europe (France, Belgium, Germany, and the Netherlands). A large dataset (>12,000 samples) from various sediment matrices (bed and flood deposits – BFD, suspended particulate matter – SPM, dated sediment cores – DSC) was set up based on monitoring and scientific research from the 1950s to the 2010s. This work investigates the impact of analytical protocols (matrix sampling, fractionation, extraction), location and time factors (related to geology and anthropogenic activities) on metal concentration trends. Statistical analyses highlight crossed-interactions in space and time, as well as between sediment matrices (metal concentrations in SPM ≃ DSC > BFD) and extraction procedures (also related to river lithology). Major spatio-temporal trends are found along several rivers such as (i) an increase of metal concentrations downstream of the main urban industrial areas (e.g. Paris-Rouen corridor on the Seine River, Bonn-Duisburg corridor on the Rhine River), (ii) a long-term influence of former mining areas located in crystalline zones, releasing heavily contaminated sediments for decades (Upper Loire River, Middle Meuse section), (iii) a decrease of metal concentrations since the 1970s (except for Cr and Ni, rather low and stable over time). The improvement of sediment quality in the most recent years in Europe reflects a decisive role of environment policies, such as more efficient wastewater treatments, local applications of the Water Framework Directive and urban industrial changes in the river valleys.

Chronological Trends and Mercury Bioaccumulation in an Aquatic Semiarid Ecosystem under a Global Climate Change Scenario in the Northeastern Coast of Brazil.

Simple SummaryManaging aquatic systems is becoming increasingly complex due to human impacts, multiple and competing water needs and climate variability. Considering the Hg concentration present in the top layers of sediment (~20 cm around 30 to 40 years) with the outer layers in the tree cores tree rings cores and in the sediment’s cores from Pacoti estuary and the Ceará estuary, overall data indicate an increase in mercury in recent years. A positive and significant correlation (p < 0.05) was revealed between Hg trends in sediments and Hg trends in annular tree rings. This shared Hg pattern reflects local environmental conditions. The results of this work reinforce the indicators previously described in the semiarid NE region of Brazil, showing that global climate change and some anthropogenic factors are key drivers to Hg exposure and biomagnification for wildlife and humans. Possible climate-induced shifts in these aquatic systems highlight the need for accurate and regionally specific metrics of change in the past in response to climate and for improved understanding of response to climate factors. These processes are inducing a greater mobilization of bioavailable Hg, which could allow an acceleration of the biogeochemical transformation of Hg.Due to global warming, in the northeastern semiarid coastal regions of Brazil, regional and global drivers are responsible for decreasing continental runoff and increasing estuarine water residence time, which promotes a greater mobilization of bioavailable mercury (Hg) and allows increasing fluxes and/or bioavailability of this toxic trace element and an acceleration of biogeochemical transformation of Hg. In this work, an application of dendrochemistry analysis (annular tree rings analysis) was developed for the reconstruction of the historical pattern of mercury contamination in a contaminated area, quantifying chronological Hg contamination trends in a tropical semiarid ecosystem (Ceará River Estuary, northeastern coast of Brazil) through registration of mercury concentration on growth rings in specimens of Rhizophora mangle L. and using the assessment in sediments as a support for the comparison of profiles of contamination. The comparison with sediments from the same place lends credibility to this type of analysis, as well as the relationship to the historical profile of contamination in the region, when compared with local data about industries and ecological situation of sampling sites. In order to evaluate the consequences of the described increase in Hg bioavailability and bioaccumulation in aquatic biota, and to assess the biological significance of Hg concentrations in sediments to fish and wildlife, muscle and liver from a bioindicator fish species, S. testudineus, were also analyzed. The results of this work reinforce the indicators previously described in the semiarid NE region of Brazil, which showed that global climate change and some anthropogenic factors are key drivers of Hg exposure and biomagnification for wildlife and humans. Considering the Hg concentration present in the top layers of sediment (~20 cm around 15 to 20 years) with the outer layers in the tree ring cores and in the sediment’s cores from Pacoti estuary and the Ceará estuary, overall the data indicate an increase in mercury in recent years in the Hg surface sediments, especially associated with the fine sediment fraction, mainly due to the increased capacity of small particles to adsorb Hg. There was revealed a positive and significant correlation (p < 0.05) between Hg trends in sediments and Hg trends in annular tree rings. This shared Hg pattern reflects local environmental conditions. The Hg concentration values in S. testudineus from both study areas are not restrictive to human consumption, being below the legislated European limit for Hg in foodstuffs. The results from S. testudineus muscles analysis suggest a significant and linear increase in Hg burden with increasing fish length, indicating that the specimens are accumulating Hg as they grow. The results from both rivers show an increase in BSAF with fish growth. The [Hg] liver/[Hg] muscles ratio >1, which indicates that the S. testudineus from both study areas are experiencing an increase in Hg bioavailability. Possible climate-induced shifts in these aquatic systems processes are inducing a greater mobilization of bioavailable Hg, which could allow an acceleration of the biogeochemical transformation of Hg.

The status and trends in radioactive contamination of groundwater at a LLW-ILW storage facility site near Sosnovy Bor (Leningrad region, Russia)

The article presents results of field studies at a site of radioactive waste storage and disposal facilities (the so-called LD RosRAO site, Sosnovy Bor, Leningrad region, Russia). The objective of the study is to overview the history and occurrence of groundwater contamination to answer the question whether the radioactive plume is historical (formed due to accidents, which happened at the beginning of the operations with the radioactive waste) or the release of radioactive solutions to groundwater is still occurring. The main method used to study the evolution of radioactive contamination is to analyze long-term observations of tritium, total alpha, and total beta activities in groundwater samples. The role of the hydrogeological conditions of the site, such as flow parameters, groundwater flow pattern, inter-aquifer downward groundwater leakage, and water-table fluctuations, in the evolution of contamination plumes has also been analyzed. In the field investigations, the integrity of the storage buildings to potential leaks was confirmed by different indirect methods. It was concluded that there is currently no significant release of radioactive components into groundwater at the LD RosRAO site and that the present conditions correspond to the stage of rehabilitation of the groundwater environment.

Assessing the contamination level, sources and risk of potentially toxic elements in urban soil and dust of Iranian cities using secondary data of published literature.

Research in urban geochemistry has been expanding globally in recent years, following the trend of the ever-increasing human population living in cities. Environmental problems caused by non-degradable pollutants such as metals and metalloids are of particular interest considering the potential to affect the health of current and future urban residents. In comparison with the extensive global research on urban geochemistry, Iranian cities have not received sufficient study. However, rapid and often uncontrolled urban expansion in Iran over recent years has contributed to an increasing number of studies concerning contamination of urban soil and dust. The present work is based on a comprehensive nationwide evaluation and intercomparison of published quantitative datasets to determine the contamination levels of Iranian cities with respect to potentially toxic elements (PTEs) and assess health risks for urban population. Calculation of geoaccumulation, pollution, and integrated pollution indices facilitated the identification of the elements of most concern in the cities, while both carcinogenic and non-carcinogenic risks have been assessed using a widely accepted health-risk model. The analysis of secondary, literature data revealed a trend of contamination, particularly in old and industrial cities with some alarming levels of health risks. Among the elements of concern, As, Cd, Cu, and Pb were found to be most enriched in soils and dusts of the studied cities based on the calculated geochemical indices. The necessity of designing strategic plans to mitigate possible adverse effects of elevated PTE concentrations in urban environments is emphasized considering the role of long-term exposure in the occurrence of chronic carcinogenic and non-carcinogenic health problems.

Wastewater monitoring in support of health surveillance of the COVID-19 pandemic

Surveillance of infectious disease pandemics is traditionally carried out by the inventory of individual clinical cases, mortality, and biological testing. Collective monitoring through the analysis of biomarkers in wastewater is a new complementary approach developed due to progress in analytical chemistry. It supports epidemiological studies for the estimation of the prevalence of viral infectious diseases within communities connected to the same wastewater sewage network. In the context of the COVID-19 pandemic, this type of approach has developed widely and rapidly around the world, due to its anticipated benefits. The article builds on early work published since January 2020 in a rapidly evolving literature. It shows that the method has limitations related in particular to the sampling strategy, analytical matrix effects, interlaboratory variability of results, and also uncertainties about individual viral excretion in feces. In almost all cases, it uses genomic detection of SARS-CoV-2 virus by quantitative PCR and is therefore unable to characterize its infectivity. The results showed a relatively good relation between genome concentrations in wastewater and numbers of confirmed cases. The virus detections seemed to appear a few days before the changes observed on the basis of the clinical and test screenings and can alert the health authorities to the geographical progression of an expected epidemic or to anticipate their reaction in the event of a new spike of the current epidemic. Knowledge of the evolutionary trends of wastewater virus contamination in cities, or even in city districts, also makes it possible to better target geographically and over time the public health management actions intended to prevent the circulation of the virus in the population served by their sewerage systems. In connection with health surveillance, the method is intended to contribute to the development of epidemiological models to predict the evolution of the pandemic at the local level. It is expected to develop into a permanent surveillance network over the territories, providing early, real-time epidemiological indications. Wastewater monitoring could also feed a pool of control samples to determine retrospectively when a new outbreak of viral infection has entered a territory.

Depth-wise elemental contamination trend in sediment cores of the Sundarbans mangrove forest, Bangladesh

In this study, depth-wise concentration variations of twenty-five elements (Na, Al, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Zn, As, Sb, Cs, La, Ce, Sm, Eu, Dy, Yb, Lu, Hf, Th and U) and their contamination levels were studied using two sediment cores from two different Ranges of the Sundarbans mangrove forest, Bangladesh. It was observed that there was a decreasing trend in concentrations of most of the studied elements from surface to the deeper layers and the rate of concentration decrement at the core from Satkhira Range was less than that of the core from Chandpai Range, indicating a more anthropogenic effect on the Chandpai range near Mongla seaport area. Different pollution indices (Igeo and EF) indicate that sediments of the Sundarbans are minor to moderately contaminated by As, Sb, Cs, REEs, Th and U. Therefore, this study suggests that proper steps should be taken to save the sensitive mangrove forest from elemental pollution.

Rapid determination of femtomolar methylmercury in seawater using automated GC-AFS method: Optimisation of the extraction step and method validation

Among ionic mercury species methyl mercury (MMHg) is the most toxic form present in the environment, which is known to be bio-accumulative neurotoxin in the aquatic food chain and could provide the major route of exposure for humans to mercury through consumption of marine food products. The availability of reliable analytical methods for evaluating spatial and temporal contamination trends of MMHg in the ocean is an important prerequisite for marine monitoring. Sound strategies for marine monitoring call also for measurement systems capable of producing comparable analytical results with demonstrated quality.A sensitive analytical procedure for environmental monitoring of MMHg content in seawater, based on specific extraction and Gas Chromatography Atomic Fluorescence Spectrometry validated according to the requirements of international guidelines and standards, ISO 17025 and Eurachem guidelines, is presented in this study.The entire measurement process was described by mathematical equations and all factors influencing the results were systematically investigated. Selectivity, working range, linearity, recovery (94 ± 4%), repeatability (3.3%–4.5%), intermediate precision (2.9%), limits of detection (0.0004 ng kg−1as Hg) were systematically assessed. The relative expanded uncertainties obtained were in the range from 16% to 25%, (k = 2).Modelling of the entire measurement process related obtained values for MMHg in seawater to the International System of units (Kg). The potential of this analytical procedure was tested and additionally validated via inter laboratory comparison exercise organised under the Geotraces programme. Obtained results were in excellent agreement with the assigned values.The proposed analytical procedure from the sample preparation to the measurement step combined with the high efficiency of the new generation of the automated MMHg analyzers is fit for purpose for routine monitoring studies on the dissolved MMHg in the costal and open ocean seawaters.

Is it safe to eat fish from the Great Lakes? An adaptive modelling-monitoring framework to assess compliance with consumption advisories

In this study, we conducted a retrospective analysis of the spatio-temporal trends of fish contamination in the Canadian Great Lakes. We subsequently formulated consumption advisories that explicitly account for all sources of uncertainty, such as model error, sampling bias, and natural variability of fish assemblages. Our analysis generated exceedance frequency maps of the tolerable daily intakes (TDIs), which showed that mercury (Hg) concentrations are generally at a safer level for consumption, whilst polychlorinated biphenyls (PCBs) continue to result in restrictive advisories. Specifically, the initial decline in PCBs has transitioned into a steady state, possibly due to the combined effects of external contamination sources and internal abiotic and biotic factors. Our assessment of the PCB decline rates required to comply with TDI thresholds over the next twenty years suggest that a small degree of reduction is needed for Walleye (Sander vitreus) across all sampled sites, whereas much faster decay rates are needed for Lake Trout (Salvelinus namaycush), especially in lower Lake Huron, Lake Erie, and Lake Ontario. We also detected a distinct Hg gradient whereby the southernmost waterbody, Lake Erie, had the lowest average concentrations, whereas the highest levels amongst the fish species sampled were registered in St. Lawrence River. Finally, we show the ability of our Bayesian approach to fish consumption advisories to produce time-specific, highly customizable, risk-assessment statements that account for the inherent variability in natural fish communities and the variant degree of empirical evidence about the contamination history in different locations around the Great Lakes.

Investigation of environmental and land use influence on watershed bacterial contamination using E. coli quantification and 16s identification

Wheeling Creek in the Northern Panhandle of West Virginia was monitored for fecal indicator bacterium Escherichia coli (E. coli). Since Wheeling Creek is used recreationally, elevated fecal coliform levels pose potential human health risks including gastrointestinal or respiratory illness. The current study included 12 sites spanning 18 stream km. For each site, weekly or bi-weekly bacteria samples were collected from the water column and water chemistry parameters were recorded. Seasonal trends in bacterial contamination and correlations with site parameters including rainfall, water chemistry, and land use were recorded. Additionally, monthly water samples from each site were enriched for coliform bacteria, amplified using 16s rRNA primers, and sequenced using Oxford Nanopore’s Flongle technology. Metagenomic analysis was used to determine patterns in the microbial community and note correlations between indicator bacteria and pathogens. Concentration of E. coli regularly exceeded the USEPA recommendation of 235 CFU/100 mL at many sites. Two sites averaged over 3,000 CFU/100 mL, while five sites averaged less than 126 CFU/100 mL. Development in the watershed correlated with E. coli concentration. Within the water chemistry parameters measured, turbidity, rainfall, pH, and temperature were the best predictors of site-level E. coli concentration, while pH, temperature, and percent developed land use were the best predictors of watershed E. coli levels. Collectively, these data can elucidate human health risk and inform remediation efforts in the Wheeling Creek watershed. This research was made possible by NASA West Virginia Space Grant Consortium, NASA Agreement # # 80NSSC20M0055, and the Wheeling Water Pollution Control Dept.

MICROBIOLOGICAL MONITORING OF HONEY

The article presents the results of determination the microbiological parameters of honey as one of the important factors which influence on the quality and safety of food.. Therefore. It was determined the quantitative and qualitative composition of honey microflora from different regions of Ukraine and also was studied the sensitivity of isolated cultures to antibiotics. The main microbiological risks are the increased level of mesophilic anaerobic facultative anaerobic microorganisms, contamination of honey with pathogenic and opportunistic microorganisms (Coliforms, Staphylococcus aureus, Salmonella, Clostridium perfringens, B. cereus) and microscopic fungi. It was found that total bacteria count was from 70 to 6,9 · 103 CFU/g. Molds were detected in 35,2 % cases, and their amount was from 50 to 320 CFU/g. Yeast-like fungi were detected in 29,4 % of samples and their amount was from 80 to 2.8 · 103 CFU/g. When identifying, the isolated microorganisms in the studied samples of honey was found microorganisms of the genus Staphylococcus, in particular, S aureus, S. vitulinis, S. simulans, S. hominis, S. cohni and also Sphingomonas paucimobilis and Streptomices spp.&#x0D; In the study of washes from hives found that total bacteria count was from 2,8 · 104 to 1,4 · 106, mold fungi from 6,9 · 103 to 6,9 · 104 CFU/cm3, yeast-like fungi from 1,4 · 102 to 2,6 · 102 CFU/cm3. In results of conducted studies was found that staphylococci of S. simulans, S. hominis, S. cohni and S. aureus were not sensitive or poorly sensitive to streptomycin, amoxicillin and cephalexin, except for the strain S. vitulinis.&#x0D; The analysis of the results of monitoring of honey by microbiological indicators revealed negative trends in general microbial contamination and contamination by certain types of microorganisms, in particular Coliforms, staphylococci and microscopic fungi.&#x0D; To prevent the emergence of microbiological risks, it is necessary to establish microbiological criteria for safety of honey, to develop methodological approaches to the bacteriological studies of honey and bees products.

Vertical profiles of trace elements in a sediment core from the Lambro River (northern Italy): Historical trends and pollutant transport to the Adriatic Sea

River sediments generally act as a sink for trace elements but, when resuspended, they contribute to long-term downstream transport of contamination, which may finally reach the marine environment. This study analyzed these processes in a complex aquatic system that includes a contaminated tributary, the Lambro River (Northern Italy) and its recipient and main Italian watercourse, the Po River, with the prodelta in the Adriatic Sea. The study was conducted from a historical perspective which, covering the last 50 years, examined the main driving events such as the inputs of contaminants, the construction of WWTPs and the evolution of environmental legislation. The time trend of trace element contamination was analyzed in a sediment core collected in the Lambro River and dated 1962–2011. The highest enrichments were found for Hg, Zn, Cu, Pb and Cd, which showed similar trends, with EF maxima in the '60s–'90s (172, 56, 40, 28 and 21, respectively), following industrial and urban development, and a general decreasing pattern after the late ‘90s. Only in the 2000s the ecological risk associated with metal contamination showed mean PEC Quotients stably below 1. The results of a literature survey on sedimentary trace elements in the Po River and the prodelta for the last 50 years were then compared to the Lambro sediment core. A significant contribution to Cu, Zn, Pb, Hg and Cd contamination was proved to derive from Lambro sediment transport. In the prodelta, increasing Ni and Cr concentrations were also evidenced, likely as a result of enhanced soil erosion in the Po basin. This study highlights the key role of WWTPs, of lower-impact industrial processes and of environmental legislation in reducing contaminant inputs. It also emphasizes the active contribution of riverine sediment-bound contamination to long-distance marine sediment quality.

Non-targeted screening of trace organic contaminants in surface waters by a multi-tool approach based on combinatorial analysis of tandem mass spectra and open access databases

Non-targeted screening (NTS) in mass spectrometry (MS) helps alleviate the shortcoming of targeted analysis such as missing the presence of concerning compounds that are not monitored and its lack of retrospective analysis to subsequently look for new contaminants. Most NTS workflows include high resolution tandem mass spectrometry (HRMS2) and structure annotation with libraries which are still limited. However, in silico combinatorial fragmentation tools that simulate MS2 spectra are available to help close the gap of missing compounds in empirical libraries. Three NTS tools were combined and used to detect and identify unknown contaminants at ultra-trace levels in surface waters in real samples in this qualitative study. Two of them were based on combinatorial fragmentation databases, MetFrag and the Similar Partition Searching algorithm (SPS), and the third, the Global Natural Products Social Networking (GNPS), was an ensemble of empirical databases. The three NTS tools were applied to the analysis of real samples from a local river. A total of 253 contaminants were identified by combining all three tools: 209 were assigned a probable structure and 44 were confirmed using reference standards. The two major classes of contaminants observed were pharmaceuticals and consumer product additives. Among the confirmed compounds, octylphenol ethoxylates, denatonium, irbesartan and telmisartan are reported for the first time in surface waters in Canada. The workflow presented in this work uses three highly complementary NTS tools and it is a powerful approach to help identify and strategically select contaminants and their transformation products for subsequent targeted analysis and uncover new trends in surface water contamination.

Twenty-year sediment contamination trends in some tributaries of Lake Maggiore (Northern Italy): relation with anthropogenic factors.

Lake tributaries collect contaminants from the watershed, which may accumulate in lake sediments over time and may be removed through the outlets. DDx, PCB, PAH, PBDE, and trace element (Hg, As, Cd, Ni, Cu, Pb) contamination was analyzed over 2001-2018 period in sediments of the 5 main tributaries and of the outlet of Lake Maggiore (Northern Italy). Sediment cores were collected in two points of the lake, covering 1995-2017 period. Concentrations were compared to Sediment Quality Guidelines (PECs), potential sources and drivers (land use, population numbers, industrial activities, hydrology) were analyzed, and temporal trends were calculated (Mann-Kendall test). PCB, PBDE, Pb, Cd, and Hg contamination derives mainly from heavy urbanization and industry. Cu and Pb show a temporal decreasing trend in the basin, likely as result of improved wastewater treatments and change in use. A recent PAH increase in the whole lake may derive from a single point source. A legacy DDx and Hg industrial pollution is still present, due to high persistence in sediments. Values of DDx, Hg, Pb, and Cu above the PECs in lake sediments and/or in the outlet show potential risk for aquatic organisms. Results highlight the key role of tributaries in driving contamination from the watershed to the lake through sediment transport.

Analysis of narwhal tusks reveals lifelong feeding ecology and mercury exposure

The ability of animals to respond to changes in their environment is critical to their persistence. In the Arctic, climate change and mercury exposure are two of the most important environmental threats for top predators.1-3 Rapid warming is causing precipitous sea-ice loss, with consequences on the distribution, composition, and dietary ecology of species4-7 and, thus, exposure to food-borne mercury.8 Current understanding of global change and pollution impacts on Arctic wildlife relies on single-time-point individual data representing a snapshot in time. These data often lack comprehensive temporal resolution and overlook the cumulative lifelong nature of stressors as well as individual variation. To overcome these challenges, we explore the unique capacity of narwhal tusks to characterize chronological lifetime biogeochemical profiles, allowing for investigations of climate-induced dietary changes and contaminant trends. Using temporal patterns of stable isotopes (δ13C and δ15N) and mercury concentrations in annually deposited dentine growth layer groups in 10 tusks from Northwest Greenland (1962-2010), we show surprising plasticity in narwhal feeding ecology likely resulting from climate-induced changes in sea-ice cover, biological communities, and narwhal migration. Dietary changes consequently impacted mercury exposure primarily through trophic magnification effects. Mercury increased log-linearly over the study period, albeit with an unexpected rise in recent years, likely caused by increased emissions and/or greater bioavailability in a warmer, ice-free Arctic. Our findings are consistent with an emerging pattern in the Arctic of reduced sea-ice leading to changes in the migration, habitat use, food web, and contaminant exposure in Arctic top predators.

Spatial distribution and risk assessment of agricultural soil pollution by hazardous elements in a transboundary river basin.

The present study aimed to evaluate the sources of pollution and the potential human and ecological risks of hazardous elements (HEs) in 40 hotspot sites of the agricultural soil around the Arvand River, Iran. The mean concentrations of As, Cd, Co, Cr, Ni, Pb, Zn, and Hg were measured to be 7.2, 0.8, 14.0, 67.9, 69.5, 63.0, 296, and 0.66 (mg kg-1), respectively. With the exception of Ni, the mean concentrations of all the elements were found to be higher than those in the background. The spatial distribution of HEs in the study area indicated an increasing trend of contamination from the north to the south. Pb, Zn, and Hg were the most enriched elements, resulting in a high pollution load. Moreover, the agricultural soil of the study area was threatened by a very high ecological risk due to the contribution of Hg, Cd, and Pb. Multivariate statistical analyses determined that the pollution sources are specified by the oil refinery emissions and effluents, irrigation with polluted water, fertilizers, dust storms, and airport emissions. The carcinogenic risk of HEs in both adults and children revealed an acceptable level; however, children faced a great chance of non-carcinogenic risk. The results provide a scientific basis for monitoring HEs and managing health risks via effective methods in the agricultural areas of the Arvand River basin.

The formation of Neoarchean continental crust in the south-east Superior Craton by two distinct geodynamic processes

The formation of the continental crust in the early Earth, and the geodynamics that drove it, are fundamental to understanding the evolution of our planet, but remain intensely debated. Here, we analysed 148 archived zircon separates of magmatic rocks for in-situ zircon U-Pb-Hf-O-trace element data, and compiled published geochronological, whole-rock geochemical and Sm-Nd isotopic data from across the south-east Superior Craton, Canada. We combine these data spatially and temporally to investigate the crustal evolution of this part of the craton in the Neoarchean, with a view to understanding its tectonic setting. In terms of zircon data, at >2704–2695 Ma, the central and north-west Abitibi demonstrate more juvenile εHf, light to mantle-like δ18O, lower (Eu/Eu*)/Y (drier/shallower crust), reduced ΔFMQ, less continental initial-U (Ui)/Yb, and more mantle-like Ui/Nb, relative to surrounding crust, which contains older, ca. 2800–2750 Ma inherited and magmatic zircon ages. Furthermore, whole-rock Sr/Y and La/Sm demonstrate the presence of a high Sr/Y TTG component (mainly intrusive) surrounding zones of low Sr/Y (mainly volcanic) component, the latter of which shows contamination trends with Mesoarchean crust. We interpret this to represent a continental-rift setting, driven by plume magmatism as represented by multiple komatiite suites. At ca. 2704–2695 Ma, there is a marked transition in multiple datasets, including; increases in δ18O, (Eu/Eu*)/Y, ΔFMQ, Ui/Yb and Ui/Nb data, together with more distinct arc-like trace element trends, suggesting a transition to north-dipping subduction. This process closed the rift system and initiated orogenesis. Subsequently, this study constrains the geodynamic setting which formed the majority of Neoarchean continental crust in the south-east Superior Craton, and the timing at which it transitioned to subduction. If these findings are replicated in other cratons, it suggests that plate tectonics was active by, or started at, ca. 2.7 Ga.