Sediment Contamination Research Articles

Potentially toxic elements contamination and health risk assessment of coastal sediments in Betoya Bay, Morocco.

This study investigated the potentially toxic elements (PTEs) contamination of Betoya Bay surface sediments to assess the degree of pollution and identify the source of these contaminants. Average PTE levels as mg/kg in Betoya Bay are ranked in descending order as Zn (22.68) > Cr (8.64) > Pb (7.24) > Ni (6.82) > As (6.62) > Cu (5.78) > Co (2.45) > Cd (0.20). The sampling sites show an increase in PTEs at station 5, probably due to runoff from the wadi, and at the first station, where fishing activity is particularly intense. At all stations throughout the year, PTE levels were unpolluted as evaluated by the geoaccumulation index (Igeo) and the pollution load index (PLI). Almost all PTEs showed a "low contamination factor" according to the contamination factor index (CF). As assessed by the contamination degree (CD), all PTE levels at all stations and seasons were "low contamination degree". The ecological risk indices (Eir and RI) indicated low to moderate ecological risk. In line with sediment quality requirements, the M-ERM-Q calculation suggests there is only a 9% chance that this particular combination of metals poses a threat. The non-carcinogenic health risk assessment showed that beach sand in the study area is entirely safe, presenting no additional health risk to children or adults. However, the carcinogenic risk showed a low to moderate carcinogenic risk for adults and a moderate to high carcinogenic risk for children. In addition, statistical analysis revealed that all PTEs are likely to have common sources, which may be related to the geology of the area.

Assessing the Interrelationship Between Microplastics and Polychlorinated Biphenyls Contamination in Chinese Mangrove Sediment

Mangrove ecosystems, critical intertidal zones at the land–ocean interface, are increasingly recognized for their role in microplastic (MP) pollution dynamics. Despite extensive research on the interaction of MPs with various chemical contaminants, the specific contamination levels of polychlorinated biphenyls (PCBs) associated with MPs in mangroves remain poorly understood. In this study, we quantified the concentrations of PCBs on MPs extracted from representative mangrove sediment samples across China, revealing values ranging from 9.80 to 13.91 ng/g. In contrast, PCB concentrations in sediment samples were found to vary between 25.67 and 69.85 ng/g. Our findings indicate a consistent level of PCB contamination on MPs across different sites, although these levels were marginally elevated compared to those in the surrounding sediments. Notably, Penta-PCBs were detected with the highest frequency across all samples analyzed. This study provides crucial insights into the occurrence and distribution of PCBs on MPs within the mangrove ecosystem, highlighting their significance in environmental contamination assessments.

Response of sediment with Ca/Al composites capping to cyanobacterial bloom decline: Blocking the formation and the release of sediment iron-bound phosphorus (Fe-P)

The immobilization of phosphorus (P) in sediments plays a pivotal role in managing lake eutrophication over the long term. Therefore, key factors that may cause uncertainties in P fixation are of increasing interest to researchers. Calcium‑aluminum composites (CA) can passivate sediment P well; however, the effect of cyanobacterial bloom decline on their sediment P remediation remains unclear. In this study, CA addition significantly reduced P equilibrium concentration as well as augmented P adsorption capacity of sediment characterized as cyanobacterial dominance zone (CDZ). The results of the simulated experiments on cyanobacterial bloom decline indicated that the algae decomposition led to a rapid decrease in dissolved oxygen (DO) level, and to release amounts of P, thus increasing the P concentration in the overlying water. The released algal P into the sediment primarily encouraged the formation of iron-bound phosphorus (Fe-P), followed by calcium-bound phosphorus (Ca-P). The subsequent anaerobic incubation led to a notable release of the newly formed Fe-P, strengthening the anaerobic P release from sediments. Conversely, CA-capping accelerated the adsorption of algal P by sediments, and promoted the formation of Ca-P in sediment from cyanobacterial P, hindering the generation of reactive Fe-P. Moreover, during subsequent anaerobic incubation, the P forms in sediments capped with CA remained stable, showing no obvious P release. These findings suggested that CA capping induced the formation of stable P from algal P and disrupted the positive feedback effect between P contamination in sediments and cyanobacterial blooms, which would provide valuable insights for the remediation of sediments in CDZ.

Occurrence and characteristics of microplastics across the watershed of the world’s third-largest river

While rivers as primary conduits for land-based plastic particles transferring to their "ultimate" destination, the ocean, have garnered increasing attention, research on microplastic pollution at the scale of whole large river basins remains limited. Here we conducted a large-scale investigation of microplastic contamination in water and sediment of the world’s third-largest river, the Yangtze River. We found concentrations of microplastics in water and sediment to be 5.13 items/L and 113.9 items/kg (dry weight), respectively. Moreover, microplastic pollution levels exhibited a clear decreasing trend from upstream to downstream. The detected microplastics were predominantly transparent in color, with fibrous shapes predominating, sizes mainly concentrated below 1mm and composed primarily of PP and PE polymers. Our analysis results indicated that compared to geographical and water quality parameters, anthropogenic factors primarily determined the spatial distribution pattern of microplastics. Moreover, the microplastic abundance in sediment upstream of the dam was significantly higher than that in the downstream sediment, while the trend of microplastic concentrations in water was opposite. Therefore, more effort is needed to monitor microplastic contamination and their ecological environmental effects of sediment before dams in future research.

Spatial distributions, potential sources, and ecological risks of heavy metals in stream sediments in Zambia

The ecological risk assessment and source identification of heavy metals (HMs) are significant for resource utilization and food security. This study aims to assess the spatial distributions, potential sources, and ecological risks of HMs in stream sediments in Zambia. Using 735 samples collected from stream sediments across the country and methods such as inductively coupled plasma mass spectrometry (ICP-MS), atomic fluorescence spectrometry (AFS), and X-ray fluorescence spectrometry (XRFS), this study determined the concentrations of the seven HMs, i.e., arsenic (As), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), and zinc (Zn). The spatial distributions of these HMs were determined using a Geographic Information System (GIS), and their ecological risks were accessed based on the analytical results of their potential sources. Additionally, this study explored the relationships between mining activities and regions with high heavy metal (HM) concentrations based on the statistical analysis of the HM concentrations and geology of the study area. The results indicate the stream sediments in Zambia exhibit average As, Cr, Cu, Hg, Ni, Pb, and Zn concentrations of 1.49 × 10−6, 19.34 × 10−6, 12.12 × 10−6, 12.70 × 10−9, 7.13 × 10−6, 12.52 × 10−6, and 16.30 × 10−6, respectively. The analytical results of the geoaccumulation index (Igeo) and potential ecological risk index (PERI) reveal the presence of relatively high As and Cu concentrations, especially in Copperbelt and North-Western provinces and areas surrounding Lusaka—the capital of Zambia. The HM contamination in stream sediments in Zambia is primarily caused by Cu and gold (Au) mining. This study exemplifies how to determine potential sources and ecological risks of HMs in stream sediments, holding important implications for nation-scale environmental contamination prevention and land utilization planning.

Assessment of heavy metal concentrations, environmental risks and human health implications in marine sediments along the coastal ecosystems of the Republic of Congo.

The aim of this study is to assess the level of heavy metals (HMs) in surface sediments along the coastal estuaries of the Republic of Congo. A variety of approaches were employed, integrating elemental analysis (Atomique Absorption Spectroscopy), environmental, ecological, health risk assessment, and source identification techniques to evaluate the distribution, origin, environmental, ecological and health risks of potentially toxic element (PTE) contamination in sediments. The ascending mean concentration (mg/kg) of Cd (0.4) < Cu (18.6) < Pb (28.8) < Zn (62.1) < Mn (107) < Mg (569.6) complied with the local background, except for Cd and Pb. However, notable variations across sampling points and sites were observed, with a strong relationship between metals and organic matter. The comparing of PTEs with USEPA international standards and sediment toxicity guidelines showed compliance. The assessment of environmental risk parameters, based on the calculation of the geo-accumulation index, concentration factor and pollutant load indices showed low pollution of sediments. The ecological risk assessment, on the other hand, revealed a low level of pollution of biota and a low toxicity risk of ecosystems related to Cd and Pb and then to Cu in some sites. Regarding human health risk assessment, related to the PTEs, the cancerogenic effect indices were calculated for Cd and Pb through ingestion and inhalation pathways, and the non-cancerogenic effect indices were calculated for all HMs through ingestion, inhalation, and cutaneous contact routes, for children and adults, and showed that the results comply with the international standards set by USEPA, ranging from 10-4 to 10-6 and less than 1, respectively, where children were more sensitive and vulnerable than adults to the effects of the PTEs. Ultimately, this study revealed sediment lithology, anthropogenic activities, and mixed origins of HMs, with a large contribution from industrial activities. However, no significant impacts are discernible in the study area. In addition to the importance of this study, it forms part of the region database and could serve as a reference for future monitoring studies, since no data are available in th Congolese coastal environment.

Sand bed river dynamics controlling microplastic flux

Microplastic contamination of river sediments has been found to be pervasive at the global scale and responsive to plastic and sediment bed properties, the flow regime and the river morphology. The physical controls governing the storage, remobilization and pathways of transfer in sand bed rivers remain unquantified. This means it is not currently possible to determine the risks posed by microplastic contamination within these globally significant river systems. Using controlled flume experiments we show that sand bed rivers can store up to 40% of their microplastic load within the sediment bed indicating that these environments can act as resilient sinks of microplastics. By linking bedform dynamics with microplastic transport characteristics we show that similarities exist between granular transport phenomena and the behavior, and hence predictability, of microplastic flux. Specifically, we demonstrate the inverse relationship between bedform celerity and microplastic retention within the bed can be used to predict microplastic flux. Further, we show that, in these environments, microplastic shape is more important than previously thought in controlling the fate of microplastics. Together, these findings are significant since they have important implications for the prediction and hence management of microplastic contamination in sand bed environments.

Sediment contamination in two German estuaries: A biomarker-based toxicity test with the ragworm Hediste diversicolor under intermittent oxygenation

Toxicity testing is an important tool for risk assessment of sediment contamination in estuaries. However, there has been a predominant focus on fitness parameters as toxic endpoints and on crustaceans as test organisms, while effects at the sub-organismal level and on other benthic taxa have received less attention. Also, interactions between sediment contamination and natural stressors such as oxygen are often neglected in traditional toxicity tests. Here we conducted a toxicity test of sediments from the Elbe and Oder (Odra) estuaries under three weeks of continuous and intermittent oxygenation, using biomarkers in an annelid, the ragworm Hediste diversicolor. Contaminated sediments affected worm survival and some biomarkers of antioxidant defense, electrophilic stress, and energy status with response ratios of above 20%. Toxic effects were most pronounced in sediments from the upper Elbe estuary, which contained high levels of heavy metals and organic chemicals. Oxygen regimes hardly changed the sediment effects, suggesting the robustness of the biomarker-based toxicity test with ragworms.

Sediment TIE Validation Study Using South Korean Domestic Species Glyptotendipes tokunagai to Evaluate Contamination with Two Heavy Metals and Ammonia

Toxicity identification evaluation (TIE) is used to support sustainable soil management. However, TIE studies for sediment contamination have been limited and no previous study has validated its applicability to a species native to South Korea, to the best of our knowledge. Therefore, this study aims to validate the applicability of domestic species inhabiting East Asia to a TIE framework. We selected Glyptotendipes tokunagai, a common benthic invertebrate in urban areas. Contaminated sediment samples were generated using cadmium, copper, and ammonia, which are the major pollutants in sediment. Three different adsorbents were chosen as pollutant removal agents to validate the applicability of TIE using G. tokunagai. In the results, G. tokunagai exhibited a mortality rate that was dependent on the concentration of each pollutant. The mortality rate dramatically decreased after adding the chosen adsorbents to the contaminated sediments. Additionally, the observed reduction in toxicant concentrations suggests that these additives are efficient for toxicant removal. In contrast, WCA10L showed a mortality higher than 20% and seems not to be a proper additive for a toxicity assay. Through this study, G. tokunagai was demonstrated to be sufficiently sensitive to sediment contaminated with different pollutants and showed reproducible measurements, making it a suitable test organism for the TIE framework. Moreover, suitable adsorbents were suggested by measuring efficiency and toxicity after the toxicant removal procedure.

PAH contamination in coastal surface sediments and associated bacterial communities

Polycyclic aromatic hydrocarbons (PAH) are semi-volatile, lipophilic, and harmful compounds that can persist for decades in a range of marine environments. There are several marine and soil microorganisms that possess enzymes involved in arene degradation. Here, we analyzed the structure (16S rRNA amplicons) and metabolic potential (inferred using phylogenetic placement) of the bacterial community in surface marine sediments from coastal waters off Concepción, Chile, and describe how microbial community patterns are shaped and altered by PAH contamination. Two depositional zones were identified, a “High PAH” area containing a mix of high and low molecular weight PAH of up to 10,350 ng∑PAH gdw−1 and with high organic matter content; and a “Low PAH” zone mostly characterized by low molecular weight PAH of up to 1810 ng∑PAH gdw−1 and lower levels of organic matter. We identified 53 hydrocarbonoclastic bacteria genera, with eight showing relatively high abundances at High PAH sites, although known PAH degrader clades were also present at Low PAH sites. With potential enzymes inferred in almost all samples, we suggest that breakdown of PAH is widespread in this area, likely resulting from the long history of local PAH emissions that may have promoted a stored microbial capacity for these degradation processes.

Potential of fishing nets for adsorption of inorganic (Cu and Pb) and organic (PAHs) pollutants

This study aimed to evaluate metals and polycyclic aromatic hydrocarbons (PAHs) adsorption on new plastic fishing nets in both laboratory and quasi-real scenario (nets submersed in marina seawater) experiments as well as in situ monitoring of these contaminants in water and sediments in lost fishing gears hotspots. The latter was inconclusive as environmental contaminants levels were very low. Laboratory experiments showed metals (copper and lead) and PAHs adsorption depended on the thickness and polymeric composition of the net, being lower in thinner nylon nets. Experiments in the marina, also showed significant contaminants adsorption, which increased over time, probably due to biofilm formation on net surface. This work showed the potential role of fishing gears as skins of pollutants, increasing organisms' exposition to contaminants present in the environment. So, initiatives to prevent the loss of fishing gear and to retrieve them are needed to reduce and/or eliminate their environmental impact.

Status of Trace Metals Contamination and Ecological Risk Assessment in Intertidal Sediments Along the Gulf of Guinea

Surface sediments from the intertidal area of Côte d’Ivoire were sampled to investigate trace metals (Hg, Cd, Cr, Cu, Pb, Zn, and As) concentrations to illustrate their spatial distribution and ecological risk of pollution. The average total organic carbon content was 2.04 ± 0.01%. Except for Cr and Zn, the spatial distribution exhibited a similar pattern for TOC, Hg, Cd, Cu, Pb, and As. The average concentrations of trace metals were less than their corresponding upper continental crust (UCC) values, except for Cd and Cr. The pollution indices indicated that sediment quality in the studied area has been impacted by Cd and the Assinie and Bleron sites were the most contaminated. A few ecological risks were posed by Hg, Cd, Cr, and Cu, based on sediment quality guidelines (SQGs). The Pearson correlation showed a significant (p < 0.05) correlation between As, Cd, Pb, Cr, and Hg, suggesting a common origin in sediments. The principal component analysis (PCA) identified As, Cr, Pb, Zn, and Hg might originate from natural source, Cd and Cu might be from natural and anthrogenic sources. Although this study presents the current status of littoral trace metals contamination level in sediments, further studies should integrate the statistical multivariate approach to determine the anthropogenic sources of the trace metals in the intertidal area of Côte d’Ivoire.

Refinement and Validation of the SPEcies at Risk Index for Metals (SPEARmetal Index) for Assessing Ecological Impacts of Metal Contamination in the Nakdong River, South Korea

The SPEcies At Risk index for metals (SPEARmetal index) was refined using updated physiological sensitivity data and validated to assess the ecological impact of metal contamination on benthic macroinvertebrate communities in the upper Nakdong River, near a Zn smelter in Korea. Biosurvey and chemical monitoring data were collected at 18 sites surrounding the smelter and nearby mines. Acute ecotoxicity tests on 20 indigenous species from the Korean peninsula were conducted and used to update taxon-specific metal sensitivity data. The refined SPEARmetal index, based on this updated sensitivity, was significantly lower than previous versions, with most values below the severe impact threshold (0.5) in the main stream. The correlation between hazard quotients in water and the SPEAR index improved, with the correlation coefficient increasing from 0.63 to 0.70. Despite consistently high benthic macroinvertebrate indices (BMIs) across the study area, generic ecological indices, such as total richness, EPT (Ephemeroptera, Plecoptera, and Trichoptera taxa richness), and Shannon’s diversity index, showed correlations with metal contamination levels. Principal component analysis identified the SPEARmetal index as the primary indicator associated with metal contamination in both water and sediment. These findings highlight the improved performance of the refined SPEARmetal index as a more sensitive and specific tool for assessing the ecological status of metal-impacted aquatic ecosystems compared to traditional indices.

Evaluation of 210Po, 210Pb, and potentially toxic element concentrations in aquatic environments and polychaetes along the southeast coast of Chennai, Tamil Nadu: a baseline report

ABSTRACT The activity concentrations of radionuclides (210Po and 210Pb) and the concentrations of potentially toxic elements (PTEs) in water, sediment, and two polychaete species (Marphysa madrasi and Namalycastis jaya) collected from 12 stations, denoted as S1 to S12, along the coast of Tamil Nadu, Chennai, in southeast India has been investigated. The average activity concentrations of 210Po and 210Pb were 0.39 ± 0.01 mBq/L and 3.30 ± 0.06 mBq/L in water, and 0.80 ± 0.02 Bq/kg and 4.21 ± 0.19 Bq/kg in sediment, respectively. Marphysa madrasi exhibited higher 210Po and 210Pb activity concentrations (37.78 ± 0.43 Bq/kg and 17.25 ± 0.22 Bq/kg, respectively) compared to Namalycastis jaya (34.40 ± 0.42 Bq/kg and 15.91 ± 0.26 Bq/kg, respectively). Maximum activity concentrations for both radionuclides in water were observed at Kalpaakam (S11) and Nemmeli (S7), while maximum sediment activity concentrations were found at Nemmeli (S7). The elevated activity concentrations in polychaetes from Nemmeli (S7) likely reflect the significantly higher 210Po and 210Pb activity concentrations observed in sediments from this site when compared to other sites. Bioaccumulation values for 210Po and 210Pb averaged 6.89 × 101 and 4.20 for M. madrasi, and 6.17 × 101and 3.84 for N. jaya , respectively. Sediment PTE concentrations followed the order: Fe > Zn > Mn > Ni > Co > Cr > Pb > Cd > Cu. Risk assessment indicated alarming levels of PTE contamination in sediments, suggesting severe anthropogenic impacts. In contrast, average PTE concentrations in polychaetes followed the order: Fe > Cu > Zn > Mn> Cr > Ni > Co > Cd > Pb. Statistical analysis revealed strong and significant correlations (p < 0.05) between PTE concentrations in sediments and polychaetes. The present study offers baseline data for evaluatingthe levels of 210Po and 210Pb in water, sediment, and polychaetes in selected locations along Chennai, Tamil Nadu, India’s southeast coast. These findings lay the groundwork for further studies of polychaetes, specifically the ecological effects of PTEs and radionuclides on coastal creatures and biomagnification.

Spatial distribution of heavy metal contamination and risk indices of surface sediments in high-altitude lakes.

Lake ecosystems in northern Pakistan are the most critical resources that maintain and regulate water flow for downstream agricultural, domestic, industrial, and ecological processes. One consequence of these processes is that ecosystems deposit heavy metals (HMs), where lake stagnant conditions result in high vulnerability of water resources. For this purpose, the present study examined HMs such as cadmium (Cd), chromium (Cr), cobalt (Co), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) concentrations in high-altitude lakes (HAL) sediments of Mansehra district, northern Pakistan. Sediment samples were collected from the five HAL. This study used HM concentrations in lake sediments for the pollution factors such as contamination factor (Cf), pollution load index (PLI), sediment pollution index (SPI), ecological risk assessment (ERA), and risk index (RI). Among HMs, Fe showed the uppermost levels of 1410mg/kg in lake sediment, while Cd with lowermost levels of 1.05mg/kg. Results revealed that most HM concentrations in HAL sediments were within the threshold of sediments quality guidelines (SQGs), except for Cd. Among lakes, the sediments of Siri Lake showed higher contamination of HMs than others. Siri Lake sediments also showed higher Cf, PLI, ERA, and RI values than others. The majority of HMs in HAL sediments showed no contamination, except for Cd (considerable) and Pb (moderate) levels to the exposed aquatic ecosystem. This study revealed that 95% of sediment samples in HAL were noted low to medium-level risks to the exposed aquatic communities. Statistical and geospatial analyses revealed that geogenic sources of contamination are a significant contributor to HM contamination of HAL sediments compared to others.

Integrated Assessment of Metal Contamination of Soils, Sediments, and Runoff Water in a Dry Riverbed from a Mining Area Under Torrential Rain Events

Dry riverbeds can transport mining waste during torrential rain events, disseminating pollutants from mining areas to natural ecosystems. This study evaluates the impact of these mine wastes on soils, sediments, and runoff/pore water in the La Carrasquilla dry riverbed (southeastern Spain). An integrated approach utilizing geochemical and mineralogical techniques was employed, analyzing water, soil, and sediment samples from both the headwater and mouth of the riverbed. Soil profiles and pore water were collected at 30 cm, 60 cm, and 90 cm deep, alongside sediment and runoff water samples. The assessment of metal(loid) contamination focused on arsenic, cadmium, chromium, copper, iron, nickel, manganese, zinc, and lead, utilizing sequential extraction to evaluate metal partitioning across soil phases. Various pollution indices, including the contamination factor (Cf), pollution load index (PLI), potential ecological risk index (RI), and metal(loid) evaluation index (MEI), were employed to classify contamination levels. The highest level of contamination was reported in the headwater, which suggested anthropogenic activities linked to the presence of mining residues as the major source of metal(loid)s. However, an active deposition of As, Cd, Cu, Fe, Mn, and Zn was reported in the topsoil at the mouth. In the headwater, a quartz and muscovite-rich zone exhibited the highest Cf for Pb (1022), primarily bound to the soil residual fraction (62.8%). At the headwater and mouth, pore water showed higher concentrations of sulfate, Ca, Na, Cl, Mg, and Mn and higher salinity than acceptable limits for drinking water or irrigation established by the World Health Organization. Runoff-water metal concentrations surpassed established guidelines, with MEI values indicating significant contamination by cadmium (36.1) and manganese (19.0). These findings highlight the considerable ecological risk of Pb and underscore the need for targeted remediation strategies to mitigate environmental impacts in the Mar Menor coastal lagoon.

Distribution and sources of polycyclic aromatic hydrocarbons in cascade reservoir sediments: influence of anthropogenic activities and reservoir hydrology.

The construction of dams has caused disruptions to river connectivity, leading to alterations in the deposition of hydrophobic organic contaminants in reservoir sediments. Further investigation is warranted to explore the impact of cascade reservoirs with differing hydrological characteristics on polycyclic aromatic hydrocarbons (PAHs) distribution in sediment. This study examines the presence of 30PAHs in the sediments collected from six cascade reservoirs situated in the Wujiang River basin during January and July 2017. The results showed that Σ30PAHs ranged from 455-3000ng/g dw (mean 1030ng/g dw). Anthropogenic activities and reservoir hydrology determined the distribution trend of PAHs in sediments, with an overall increase from upstream to midstream and then a decrease downstream. The PAH levels were highly linked to the secondary industry (P < 0.05). This was further supported by the relationship between the PAH emissions from coal combustion and traffic sources analyzed by the positive matrix factorization model and economic parameters in the wet season (P < 0.01). At the same time, reservoir age (RA) showed a positive correlation with PAH concentrations (P < 0.05), while hydraulic retention time (HRT) exhibited a negative correlation with PAH levels (P = 0.03). The relationship between total organic carbon (TOC) and PAHs in stream sediments worldwide was nonlinear (P < 0.01), with PAH concentrations initially rising and then falling as TOC levels increased. Concerns regarding carcinogenic risk were raised due to contributions from coal and vehicular sources, with the risk increasing with RA.

Pollution and Ecological Risk Assessment of Potentially Toxic Elements in Sediments Along the Fluvial-to-Marine Transition Zone of the Don River

The quality of sediments in the mixing zone of river freshwater and marine saline water as an important geochemical barrier for potentially toxic elements (PTEs) remains poorly understood. This study aims to analyze the current pollution with PTEs and associated ecological risks in sediments of the Don River delta and the surrounding area of the Taganrog Bay of the Sea of Azov (Russia). The PTE content was determined in fifty-four collected samples using the WDXRF and assessed using geochemical and ecotoxicological indicators. The source of Cr, Mn, Ni and Pb is mainly river runoff, and Cu, Zn and Cd are from a variety of anthropogenic sources. As shown by the assessment of the geoaccumulation index (Igeo), single pollution index (PI) and contamination factor (CF), these elements are the priority pollutants. According to these estimates, high and very high contamination of sediments in the estuarine zone of the Don River with Cd and Pb was detected in 72–94% and 2–57% of samples, respectively. However, environmental risks are determined almost exclusively by the level of Cd. Total contamination as assessed by the Nemerow pollution index (NPI), modified degree of contamination (mCd) and metal pollution index (MPI) is of concern in 83–98% of the samples studied. The most heavily polluted sediments are in the vicinity of residential areas of the Taganrog Bay. Despite the lower average pollution levels of deltaic sediments, freshwater biota are exposed to higher potential toxic risks of adverse effects by PTE, particularly from Ni and Pb. Thus, the complex hydrological regime and uneven anthropogenic impact predetermine the geochemical state of the sediments of the estuarine zone of the Don River.

Method development and comprehensive study of matrix effects for the determination of trace organic contaminants in lake sediments

The presence of trace organic contaminants (TrOCs), such as pharmaceuticals, personal care products, additives, and polar pesticides in sediments of rivers and lakes highly impacted by anthropogenic activities makes sediments a secondary source of contamination for aquatic ecosystems. Considering this, a method for analyzing 44 TrOCs of diverse nature (including five transformation products, 13 pharmaceuticals, five personal care products, 14 pesticides, and seven additives) was developed and validated. It is based on extraction by pressurized liquid extraction (PLE), followed by purification and pre-concentration by solid phase extraction (SPE) and quantification by liquid chromatography coupled to a triple quadrupole mass spectrometer (LC-QqQMS). The method was optimized according to dispersant type, temperature, and extraction solvent. The influence of organic matter in sediments on quantitative analysis was also investigated in detail. Matrix effects were highly and significantly correlated (r=-0.9146, p < 0.0001) with retention time. Using internal standards showed the best results for effectively correcting matrix effects without affecting method sensitivity. The method was then validated according to key figures of merit: linearity (R2 > 0.990), extraction recoveries (> 60 % for 34 compounds), trueness (bias % < 15 %), precision (relative standard deviation < 20 %) and matrix effects (between -13.3 % and 17.8 %). This method can be applied for routine analysis of TrOCs in different sediment matrices. The method was applied to ten lake sediment samples collected in Québec, Canada. Results demonstrated the presence of 17 compounds in at least one lake at concentrations between 0.07 to 1531 ng g-1. The reported concentrations provide a first picture of the occurrence of chemical stressors in sediments of small lake highly anthropized ecosystems in Eastern Canada.

Pollution status of microplastics in the sediments of warm monomictic Dal lake, India: Abundance, composition, and risk assessment

This report presents the first investigation of microplastic (MP) contamination in the shoreline sediments of Dal Lake, Jammu and Kashmir, India. The MP concentrations ranged from 503 to 3154 MP/kg, with a notable seasonal variation. The highest concentrations of microplastics occurred in the Spring, ranging from 467 to 3445 MP/kg. Microplastics were identified using optical microscopy, Fourier Transform Infrared spectroscopy, and thermogravimetric analysis. Polymer analysis revealed that the Gagribal basin was contaminated with polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyamide (PA), and polyethylene terephthalate (PET). In contrast, the Nigeen basin mainly comprises PE, PP, and PS. The significantly elevated Polymer Hazard Index (PHI) values, exceeding 1000 in the Gagribal basin, were attributed to the presence of PVC. Sediment quality was assessed using Pollution Load Index (PLI), Potential Ecological Risk Index (PERI), and PHI. Health risk metrics, such as estimated daily intake (EDI) and microplastic carcinogenic risks (MPCR), were also evaluated. There is a positive correlation between microplastic abundance and total organic carbon (TOC), total phosphorus (TP), and total nitrogen (TN). The Nigeen basin, characterized by a higher proportion of less hazardous polymers like PP, exhibited greater TOC levels due to enhanced microbial degradation of microplastics. Conversely, the Gagribal basin, with its higher presence of toxic polymers like PVC, had lower TOC levels, likely due to these compounds' inhibition of microbial activity. This study provides crucial insight into the spatial distribution and ecological impact of MPs in Dal Lake, setting the stage for future research on their effects on aquatic ecosystems.