Sediment Contamination Research Articles

Evaluation and mitigation of potentially toxic elements contamination in mangrove ecosystem: Insights into phytoremediation and microbial perspective

Mangroves, essential coastal ecosystems, are threatened by human-induced Potentially-toxic-elements (PTEs) pollution. This study analyzed PTEs distribution, phytoremediation potential, and rhizosphere microbial communities in Taiwan's Xinfeng mangrove forest. Significant variations in physicochemical and PTEs concentrations were observed across adjacent water bodies, with moderate contamination in the river, estuary, and overlying water of mangroves sediment. The partition-coefficient showed the mobility of Bi, Pb, Co, and Sr at the water-sediment interface. The geochemical-indices revealed high Bi and Pb contamination and moderate Zn, Sr, Cu, and Cd contamination in sediment. The overall pollution indices indicated the significant contamination, while moderate ecological risk was found for Cd (40 ≤ Eri < 80). Mangroves Kandelia obovata and Avicennia marina exhibited promising PTEs phytoremediation potential (Bi, Cd, Mn, Sr, and Co). Metagenomics indicated a diverse microbial community with N-fixation, P-solubilization, IAA synthesis, and PTEs-resistance genes. These findings underscore the need for targeted conservation to protect these critical habitats.

Feeding of the crab Eriphia gonagra (Fabricius, 1781) (Decapoda: Brachyura: Eriphiidae) as a tool to assess the impacts of oil spills

ABSTRACT This study aimed to observe changes in the diet of crab Eriphia gonagra due to the oil spill that occurred in 2019 on two beaches on the Pernambuco coast (Gaibu and Carneiros Beach) Northeastern, Brazil. Changes in the species feeding were investigated considering the periods before, during, and after of the spill and correlated with the analysis of sediment contamination Polycyclic Aromatic Hydrocarbons (PAHs) and Trace Metals (TM). 160 specimens were analysed. 24 food items were found, with a prevalence of Mollusca (fragment) and Macroalgae in the diet. There was no detection of oil fragments in the stomachs of animals, however, different patterns were observed in the feeding of the species studied in the BEF, DUR, and AFT periods of the spill. A generalist habit, it was possible to observe changes in captured items, thus we observed a diet with low nutritional levels caused mainly in impacted environments. Two factors may be prevalent in explaining the impacts caused by the feeding of E. gonagra in Carneiros Beach. The first was the decrease in prey that died after the arrival of the oil, the second was the lasting effects of contaminants on the predation capacity of the species.

Environmental and human health risk associated with heavy metals in sediment of a tropical river in India

ABSTRACT Heavy metals persist in the sediment and can induce toxicological effects on living organisms. For analysing the risk of heavy metals, geochemical fractionation is beneficial. These geochemical fractions or speciations help to determine the heavy metals availability, mobility, toxicity, enrichment, and various risks. Here, we show how heavy metal contamination of sediment poses risks to both the ecosystem and human beings. We found significant Zn, Co and Cd contamination by analysing the geoaccumulation index. We also observed higher geoaccumulation index values for the pre-monsoon season than the post-monsoon one. Furthermore, pollution load index indicated gradual contamination of heavy metals in the sediments. This study's risk assessment and modified risk assessment codes showed low or no risk, but contamination factors indicated moderate to high risk. Our analysis of the effective range median mean quotient revealed some sampling stations as medium to high-priority sites. Similarly, probable effect level mean quotient designated some sampling stations as medium-low priority sites. We anticipated a moderate to significant mortality effect on the organisms from toxicity unit index values. Potential ecological risk index indicated a very high ecological risk on the Mahananda River. Furthermore, we predicted non-carcinogenic health hazards and carcinogenic health risks in the river's sediment.

Assessment of potentially toxic element contamination in wetland sediments of Boracay Island, Philippines

Boracay Island, Philippines, famous for its white sand beaches, has wetlands increasingly threatened by human activities. This study evaluated the ecological state of Boracay Island's wetlands and assessed the consequences of anthropogenic activities on sediment quality. Results showed that sediments from Wetland Nos. 3 and 4 have higher concentrations of potentially toxic elements (PTEs) than Wetland No. 1. Comparative analysis with other Southeast Asian wetlands revealed that Boracay's sediments contain the highest average values of As, Cd, Cu, Ni, Zn. Enrichment factor values suggest that the moderate enrichment of Cd, Cr, Cu, Mo, Pb, and Zn in the wetland sediments can be attributed to anthropogenic activities on the island. Elevated concentrations of Cr, Cu, and Zn above interim sediment quality guidelines indicate occasional adverse biological effects on aquatic biota. These findings provide a crucial baseline for future pollution monitoring and highlight the need for ongoing conservation efforts in Boracay's wetlands.

Global patterns of lake microplastic pollution: Insights from regional human development levels

Microplastics have emerged as a pervasive pollutant across various environmental media. Nevertheless, our understanding of their occurrence, sources, and drivers in global lakes still needs to be completed due to limited data. This study compiled data from 117 studies (2016–May 2024) on microplastic contamination in lake surface water and sediment, encompassing surface water samples in 351 lakes and lake sediment samples in 200 lakes across 43 countries. Using meta-analysis and statistical methods, the study reveals significant regional variability in microplastic pollution, with concentrations ranging from 0.09 to 130,000 items/m3 in surface water and from 5.41 to 18,100 items/kg in sediment. Most microplastics were under 1 mm in particle size, accounting for approximately 79 % of lake surface water and 76 % of sediment. Transparent and blue microplastics were the most common, constituting 34 % and 21 % of lake surface water and 28 % and 18 % of sediment, respectively. Fibers were the dominant shape, representing 47 % of lake surface water and 48 % of sediment. The primary identified polymer types were polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET). Countries like India, Pakistan, and China had higher contamination levels. Positive correlations were found between microplastic abundance in surface water and factors like human footprint index (r = 0.29, p < 0.01), precipitation (r = 0.21, p < 0.05), and net surface solar radiation (r = 0.43, p < 0.001). In contrast, negative correlations were observed with the human development index (r = −0.61, p < 0.01) and wind speed (r = −0.42, p < 0.001). In sediment, microplastics abundance correlated positively with the human footprint index (r = 0.45, p < 0.001). This study underscores the variability in microplastic pollution in global lakes and the role of human activities and environmental factors, offering a valuable reference for future research.

Biodegradation of &lt;i&gt;n&lt;/i&gt;-Alkanes in Oil-Contaminated Bottom Sediments under Bioelectrochemical Stimulation

Degradation of oil hydrocarbons artificially introduced into bottom sediments in a bioelectrochemical system of a membrane-free (silt) type was studied. Passive bioelectrochemical stimulation by means of electrodes connected by an external circuit with a resistance of 1 kΩ, with an average electric current of ~85 µA was found to cause an increase in degradation during two months from 23.0 to 57.9%. Contamination of bottom sediments with oil (1.32 g/kg) slightly decreased the current in the external circuit of the bioelectrochemical system. The relationship was revealed between the degree of oil degradation and predominant utilization of the lighter n-alkanes in the C14H30–C30H62 series, compared with both the original oil and the residual hydrocarbons of the control. An increase in the representation of the alkB alkane monooxygenase genes relative to the 16S rRNA gene in the total DNA isolated from the sediments was induced by the introduction of hexadecane, both in the case of electrochemical stimulation and in the control. The results may be of interest for the development of new methods of bioelectrochemical removal of organic pollutants from anaerobic environments.

Long-Term Effects of 90Sr and 239+240Pu Contaminated on the Seafloor Sediment on the Transfer through Marine Food Web: Sensitivity to the Physical Property- and Sediment-Related Parameters

This study, as a follow-up to the &lt;sup&gt;137&lt;/sup&gt;Cs study of Kim et al. (2023), performs a set of sensitivity experiments on ocean physical properties and sediment-related parameters based on initial bottom contamination of &lt;sup&gt;90&lt;/sup&gt;Sr and &lt;sup&gt;239+240&lt;/sup&gt;Pu in the upper sediment layer. Both studies utilizes the Extended BURN model proposed by Bezhenar et al. (2016). The initial contamination levels were set to 3 and 0.4 Bq/kg, respectively, based on observations off the coast of Fukushima. The sensitivity experiments were divided into EXP-WOHAD, which examined the effects of the vertical diffusion coefficient and vertical sediment flux, and EXP-WHAD, which investigated the effects of ocean currents. The results of the EXP-WOHAD experiments showed that both radionuclides are more sensitive to sediment fluxes than to vertical diffusion coefficients. For both &lt;sup&gt;90&lt;/sup&gt;Sr and &lt;sup&gt;239+240&lt;/sup&gt;Pu, transport was dominated by transport to the intermediate sediment layer rather than to seawater. Specifically, for &lt;sup&gt;239+240&lt;/sup&gt;Pu, transport to seawater was insignificant due to its strong sorption properties in sediments. In terms of bioaccumulation, &lt;sup&gt;90&lt;/sup&gt;Sr accumulated most in fish and invertebrates, while &lt;sup&gt;239+240&lt;/sup&gt;Pu accumulated most in invertebrates, followed by zooplankton. Notably, &lt;sup&gt;239+240&lt;/sup&gt;Pu showed high bioaccumulation despite its low initial sediment contamination. The changes in radioactivity concentrations in the EXP-WHAD experiments were similar to those in the EXP-WOHAD experiments, and the bioaccumulation trends in biota were also comparable. This study confirms that the accumulation of radionuclides in seawater, intermediate sediments, and biota is sensitive to the marine physical environment and varies by nuclide. When the sediment flux increased by a factor of 100, the remaining radioactivity levels of &lt;sup&gt;90&lt;/sup&gt;Sr and &lt;sup&gt;239+240&lt;/sup&gt;Pu in biota after 100 years showed a significant reduction, decreasing by more than 900 and 30,000 times, respectively; it highlighting the importance of parameterization according to the physical environment of the area of interest.

Legacy and emerging flame retardants in sediments and wastewater treatment plant-derived biosolids

A baseline assessment of legacy and emerging flame retardant chemicals was performed in inland and transitional sediments as well as biosolids emanating from a selection of wastewater treatment plants (WWTPs) in Ireland. A selection of 24 polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and chlorinated organophosphate esters (Cl-OPEs) were quantified in: 81 inland and transitional sediment samples collected during 2023; 39 transitional sediments collected between 2018 and 2022; and 21 biosolid samples collected from 7 WWTPs over 4-month intervals in January, May, and September 2023. Highest concentrations of BDE-209 and several Cl-OPEs were detected in both sediment and biosolid samples, while most PCBs and penta-/octa-BDEs were comparatively low. Moderate levels of PBDEs and Cl-OPEs were detected in Irish sediments compared to similar studies conducted internationally. In biosolid samples, levels of BDE-209 were on the higher end of figured reported worldwide while levels of Σ8Cl-OPEs were the highest relative to comparable international studies. PCBs meanwhile are on the lower end of international levels for both biosolids and sediments. Based on available predicted no-effect concentrations (PNECs), the majority of compounds assessed were found to be of low-risk based on their levels in sediments with the exception of TCIPP (Risk Quotient – RQ = 1.354 = high risk) as well as EHDPP, TEHP, PCB-118, and PCB-52 (RQ = 0.948, 0.576, 0.446, and 0.257 respectively = moderate risk). Similar risk assessment could not be performed on contaminants in biosolids, though levels of BDE-209 were on the higher end of figured reported worldwide (avg = 3155 ng/g) while levels of Σ8Cl-OPEs were the highest relative to comparable international studies (avg8 = 3290 ng/g). As the legacy PBDEs and PCBs have been listed as persistent organic pollutants (POPs) and replacement flame retardants such as Cl-OPEs have been flagged by programmes such as human biomonitoring for EU (HBM4EU) and the NORMAN Network as chemicals of emerging concern, continued monitoring of these moderate and high-risk contaminants in sediments, as well as an investigation of potential contamination of the food chain through land-spreading of biosolids on agricultural lands, would be warranted.

Assessment of metal-associated health risk in different trophic levels in tropical estuary on the southeast coast of India

Metal contamination in coastal and marine ecosystems has become a significant global concern due to its hazardous characteristics, environmental persistence, and ability to bioaccumulate in aquatic ecosystems. This poses a serious threat to the environment and the health of humans worldwide. To address these concerns, this study estimated the concentrations of metals in various trophic levels, including phytoplankton, zooplankton, bivalve, and fish. Monthly sampling was carried out in Pondicherry Fishing Harbor (PFH) and Pondicherry Open Sea (POS) between January 2017 and December 2018. The value of Cd, Pb, Cr, Co, Ni, Cu, Zn, and Mn in sediment at the PFH was considerably higher compared to the POS, indicating the impact of human activity there. The contamination factor (CF) for other metals was <0.5, suggesting minor contamination in the Pondicherry coastal sediment, the CF value for Cd was higher at PFH. Comparably, the risk index (RI) at the PFH was likewise greater because of Cd, leading to an overall risk grade of “considerable” at the PFH whereas it was “low” at the POS. The marine pollution index (MPI) showed minimal values in fish regardless of the collection sites, which was calculated based on the values of all metals. The estimated daily intake, target hazard quotient, and hazard index assessed for potential human health risk suggest that the values were within acceptable thresholds for adults and children for fish consumption from POS. However, the direct consumption of bivalve for the long term poses significant non-carcinogenic health risks in both age groups, particularly in children, who are 1.31 times more susceptible than adults. These findings highlight the need to evaluate the presence of metals in the food chain to determine their transfer to the different trophic levels, which can help mitigate the associated risks for sustainable coastal ecosystem management.

Assessment of heavy metal contamination and trophic status of coral reef sediments of the Lakshadweep Archipelago, Arabian Sea

This study investigated the distribution, contamination status, and ecological implications of heavy metals in the Lakshadweep Archipelago corals and coral reef sediments and the role of labile organic matter on metal accumulation in sediments. Heavy metal concentrations were relatively higher in the inter-tidal sediments than in the lagoon and the corals. The geochemical indices generally indicated the low anthropogenic contribution of heavy metals in sediments, and according to the sediment quality guidelines, there are no adverse effects on the biota. Sedimentary biochemical constituents are dominated by carbohydrates (CHO) followed by Lipids (LPD) and Proteins (PRT), and the low values of PRT: CHO and LPD: CHO ratios indicated aged, refractory organic matter with low nutritional quality. A portion of CHO may be derived from terrestrial sources, and statistical analyses revealed that CHO and LPD are the potential carriers of toxic metals such as Cd, Co and As into the coral reef environment. The biota-sediment accumulation factor (BSAF) showed Cd as a macro concentrator and Zn, Ni, V and As as micro-macro concentrators in Lakshadweep corals.

Quantification of heavy metal contamination and source in urban water sediments using a statistically determined geochemical baseline

Geochemical baselines (GBs) play a crucial role in discerning natural variability from anthropogenic impacts on elemental composition within the environment. However, their applicability in quantifying the contribution of pollution sources to heavy metal contamination in sediments remains understudied. This research aimed to assess the degree of contamination and local pollution source attribution by leveraging geochemical baselines derived from statistical techniques, specifically the relative cumulative frequency (RCF) and 2σ-iterative (2σ-I) methods. In the urban water systems of Ma’anshan City, the major iron ore centre in eastern China, we observed concentration ranges of Cr, Cu, Ni, Pb and Zn in 36 sediment samples ranging from 66.89 to 352.08 mg/kg, 22.01 to 133.37 mg/kg, 22.66 to 50.80 mg/kg, 14.66to 264.37 mg/kg and 73.30 to 2707.46 mg/kg, respectively. RCF and 2σ-I techniques yielded similar GBs with no significant differences (p > 0.05). The geo-accumulation index and contamination factor analysis showed a sediment heavy metal accumulation rank of Zn > Pb > Cr > Cu > Ni. The contribution percentage of pollution sources varied with land functional type of watershed. For industry-influenced sediments, the contribution of local sources to Cr, Cu, Pb and Zn was significant, with shares of 43%–88%. Overall, this study highlights the valuable insights provided by GBs for effective management of urban aquatic environments.

Microplastics contamination through a mighty estuarine island: Distribution, influencing factors, and risk assessment

The global concern over microplastic (MP) contamination in diverse ecosystems is well-established, yet Nijhum Dwip Island (NDI), known for its ecological diversity, has not undergone a comprehensive study addressing the extent of MP pollution. This research aims to evaluate the spatial distribution, influencing factors, and ecological risks of MPs in both sediment and surface water surrounding NDI, situated in the Northern Bay of Bengal. A meticulous collection of 40 sediment and 40 tidal water samples from various sites facilitated a detailed analysis. The mean abundance of MPs in sediment was 138.39 ± 34.15 pieces/kg, while in water, it was 72.83 ± 30.76 pieces/m³. Various shapes observed on NDI included films, fragments, fibers, and foams, with fragments dominating in sediment (64.05 %) and water (61.51 %). Analysis of FTIR spectra identified two primary polymer types, namely polyethylene (PE) at 57 % and polypropylene (PP) at 40 %. The results indicated elevated pollution levels on NDI, with sediment and water pollution load index measuring 1.32 and 2.01, respectively, signifying significant MP contamination in both compartments. Given the island's rare biodiversity, the vicinity of wastewater sewages, anthropogenic activities, and atmospheric deposition, could be behind MP contamination in water and sediments. No strong correlation between MP and physiochemical properties in water and PCA biplots showed their similar distribution, whereas MP abundances in sediment were significantly correlated with pH and organic matter (p<0.05), signifying a pivotal role in transporting MPs in the aquatic environment. Two canonical variables were identified as important by canonical correlation analysis, demonstrating the interdependence of MP contamination at the sample sites. This research contributes to better insights into the occurrence of MP in the rare islands, which are ecosystems that have been hardly examined for this type of pollution, and it can report sustainable interventions to lessen MP inputs to the Bay of Bengal.

Status, Sources, and Risks of Heavy Metals in Surface Sediments of Baiyangdian Lake and Inflow Rivers, North China

Baiyangdian Lake, recognized as the largest freshwater body in northern China, plays a vital role in maintaining the regional eco-environment. Prior studies have pointed out the contamination of sediments with heavy metals, raising concerns about eco-environmental challenges. Therefore, it is imperative to evaluate the current pollution levels and ecological threats related to heavy metals found in the sediments of Baiyangdian Lake as well as in its inflow rivers. In May 2022, surface sediments with a depth of less than 20 cm were analyzed for Cu, Zn, Pb, Cr, Ni, As, Cd, and Hg to determine the pollution status, identify sources of pollution, and evaluate potential ecological risks. A range of evaluation methods used by predecessors such as geo-accumulation index (Igeo), enrichment factor (EF), ecological risk index (RI), sediment quality guidelines (SQGs), positive matrix factorization (PMF), absolute principal component score-multiple linear regression model (APCS-MLR), chemical mass balance (CMB), and UNMIX model were analyzed. After comparison, multi-methods including the geo-accumulation index (Igeo), absolute principal component score-multiple linear regression model (APCS-MLR), ecological risk index (RI), and sediment quality guidelines (SQGs) were utilized this time, leading to a better result. Findings reveal that pollution levels are generally low or non-existent, with only 1.64% of sampling sites showing close to moderate pollution levels for Cu, Pb, and Zn, and 4.92% and 1.64% of sites exhibiting close to moderate and moderate pollution levels for Cd, respectively. The main contributors to heavy metal presence are pinpointed as industrial wastewater discharge, particularly Cu, Zn, Pb, Cd, and Hg. The ecological risks are also relatively low, with 4.92%, 1.64%, and 1.64% of sampling sites demonstrating close to moderate, moderate, and strong risks in the inflow rivers, respectively. Additionally, only one site shows moderate potential biological toxicity, while the rest display non-toxicity. These findings will update our cognition and offer a scientific basis for pollution treatment and ecosystem enhancement for government management.

Assessment of Heavy Metal Contamination in Water, Crab (Scylla senrata) and Sediments in Oil and Non-Oil Producing Communities in Akulga Local Government Area, Rivers State, Nigeria

Assessment of Heavy Metal Contamination in Water, Crab (Scylla senrata) and Sediments in Oil and Non-Oil Producing Communities in Akulga Local Government Area, Rivers State, Nigeria

A stringent failure: Regulators do not use available tools to protect aquatic ecosystems from clearcut forestry impacts in New Zealand

Effective regulation of land-use activities in steepland areas is crucial to protect downstream ecologies and human life as intense rainfall disturbances become more frequent globally. In Aotearoa New Zealand extensive synchronous clear-cutting of Pinus radiata monocultures on steep convergent landforms, and associated earthworks, causes ongoing accelerated erosion, excessive sedimentation, and debris-laden landslides after adverse weather events. This study examines the implementation of national forestry regulations established in 2018, which also enable regional councils to create more stringent rules to protect aquatic ecosystems. All sixteen councils were surveyed in 2021 and 2022 for stringency in planning provisions; and four regions seriously affected by Cyclone Gabrielle in 2023 were resurveyed in 2024. The cyclone caused loss of human life and calamitous damage to housing, infrastructure, and productive land uses from floods exacerbated by clearcut logging debris. All councils had administratively adopted the national regulations into their existing freshwater and coastal resource management plans. Twelve councils retained existing rules that conflicted with the regulations, but these rules do not protect all regionally significant aquatic ecosystems nor minimise landslide risks. No council, except Gisborne, had instigated the expensive and lengthy statutory resource management plan change process, nor taken a ‘strategic and principled’ approach to develop more stringent regulations, such as tougher restrictions on clear-cutting, earthworks, and replanting on steep erosion-prone convergent landforms to protect aquatic ecosystems and vulnerable communities. The government did tighten the management of logging debris after the cyclone, but the national regulations remain ineffective in addressing clear-cut practices maladaptive to intense rainfall and continue to permit replanting on convergent landforms. The regulations need urgent amendment to require councils to develop and implement a strategic and principled approach to stringency to better protect aquatic ecosystems, human life, economic livelihoods, and public infrastructure. Water quality monitoring is also currently inadequate, as no council systematically monitors the effects of forestry activities on sedimentation rates, which inhibits the ability to compare across and between regions. Foresters are not required to monitor water quality, which also stymies assessments of compliance and policy effectiveness. Councils regularly monitor rivers, lakes, and estuaries, but rarely the effects of individual land uses. This means that sediment or other contaminants cannot be parsed to different land use activities, undermining attempts to set catchment limits. It can also take decades at current monitoring levels to defensibly show any water quality improvements after changes to land use regulations. The current environmental limits approach of setting individual water quality attribute targets is highly unlikely to drive changes to maladaptive and ecologically degrading land uses. A new environmental management approach is needed that prohibits or effectively constrains hazardous and adverse activities.

Microplastic and heavy metal contamination in sediments of the high-altitude Nundkol Lake of northwestern Himalayas-Kashmir

This study investigates heavy metal and microplastic contamination in the sediment of Nundkol Lake, a high-altitude glacial lake in the northwestern Himalayas. Sediment analysis revealed heavy metal concentrations significantly exceeding background levels, with average concentrations of cobalt (Co), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), zinc (Zn), and chromium (Cr) recorded at 40.991 ppm, 54.434 ppm, 87,843.59 ppm, 1544.566 ppm, 83.288 ppm, 16.312 ppm, 104.571 ppm, and 106.514 ppm, respectively. Notably, the highest levels of Cu, Fe, Mn, and Pb were observed in sample GL2, indicating potential local geochemical anomalies. The trace elements were quantified using a Graphite Furnace - Atomic Absorption Spectrophotometer (Perkin Elmer-PinAAcle 900AA) for high precision.Microplastic analysis revealed an average abundance of 76±12.08 items/kg dry weight, predominantly fibers. The microplastics were mostly red (55.26 %), blue (36.84 %), orange (5.26 %), and green (2.63 %). Raman spectroscopy identified Polyamides (PA) as the predominant type (86.5 %), with the remainder being Polyethylene (PE) and Polypropylene (PP). The results suggest tourism, fishing, and trekking activities as major contributors to microplastic presence. This study uniquely combines the assessment of heavy metal and microplastic contamination in a high-altitude lake, providing a comprehensive view of pollutant dynamics. The findings highlight the need for tailored mitigation strategies and comprehensive monitoring programs to protect this fragile region. Applications include informing environmental policy, guiding pollution mitigation efforts, and promoting sustainable tourism practices. This study offers valuable insights into the environmental health of high-altitude lakes and underscores the need for efforts to mitigate anthropogenic impacts.

Assessing Trace Metal Contamination and Associated Risks in the Kossan River Ecosystem, Southern Côte d'Ivoire

Trace metals accumulate in aquatic systems and can pose a threat to human health and wildlife. In recent decades, human activity has become the main source of metals in the environment. In order to gain a better understanding of metal contamination in Ivorian rivers impacted by human activity, and to help set up a database, we studied the distribution of arsenics (As), cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) in the Kossan River. A total of 21 surface water and sediment samples were taken at 7 stations along the River Kossan between March 2019 and July 2020. Total concentrations of the metals were analyzed by atomic absorption spectroscopy (AAS). Carcinogenic and non-carcinogenic risks were assessed in surface water. Contamination indices such as EF, CF; Igeo and PLI were calculated to determine the level of sediment contamination. Ecological risk indices Er and RI were used to assess the potential risks associated with metals. The concentrations of As, Pb, Cd, Cu and Zn found in surface water samples fell within the following ranges: 2.03 - 17.19, 1.752 - 13.264, 0.067 - 0.774, 17.44 - 2369.11 and 136.72 - 3669.37 µg/L, respectively and in sediment: 0.69 - 4.60, 2.10 - 11.30, 0.13 - 5.00, 1.70 - 28.20 and 4.10 - 90.30 µg/g, respectively. The results showed high levels of As, Cu, Pb and Zn contamination in places, above WHO limits. The calculation of non-carcinogenic and carcinogenic risk indices revealed that arsenic and copper can present major health risks for humans through the consumption of water. Cd concentrations exceeded geochemical background values. The results suggest moderate to very severe Cd contamination of the sediments by anthropogenic origin at certain sampling points. In general, the results of the ecological risk indices revealed low to moderate levels of contamination for metals, with the exception of heavy cadmium contamination in the river. The highest concentrations of trace metals were observed in water and sediment samples collected from stations with high anthropogenic pressure. The continuing intensification of human activity may in the long term present a major risk to man and his environment, hence the need to set up a system for monitoring river watercourses and to develop a system for remediating trace metals in river water such as phytoremediation.

Трансформация радиоактивного загрязнения донных отложений Калининградского залива в период 2011–2023 гг.

The article presents the data of radioecological research of the bottom sediments in the Russian zone of the Vistula Lagoon in 2011–2023. According to research, the specific activity of 137Cs in the bottom sediments of the Lagoon was in the range of 3,9–165 Bq/m3. 137Cs is the main technogenic radionuclides that makes the greatest contribution to the pollution of the Lagoon. Contamination of the bottom sediments with 137Cs is determined by the redistribution of mainly post-Chernobyl fallout. The 137Cs accumulation was recorded in the northern deep-water part of the Primorskaya Bay. According to observations, the effective half-life of 137Cs activity in the sediments of the Lagoon is 10,4–42 years. The content of natural radionuclides is: 226Ra – from 9,0 to 35,3; 232Th – from 3,8 to 43,2; 40K from 227 to 715 Bq/kg. The NRN specific activity in the sediments of the Lagoon did not exceed 153 Bq/kg, which was significantly lower than the established safe level (370 Bq/kg), allowing their handling without restrictions. The correlations between the content of 40K, 226Ra, 232Th in the bottom sediments of the Lagoon were established with the type of sediment

Uncovering sediment pollution sources: A comparative assessment of two South African Estuaries

Richards Bay Harbour is South Africa's largest and busiest deep-water port by tonnage, and this ongoing shipping and port activities will expectedly result in metal contamination issues. The adjacent Mhlathuze Estuary is a nature reserve with a long history with Richards Bay Harbour and may be prone to metal contamination from multiple sources. The study investigates the sources of contaminated sediments in these two South African estuaries arising from their proximity to various anthropogenic activities. Investigating these sources of contamination is crucial for developing effective pollution control strategy since Richards Bay Harbour and Mhlathuze Estuary are regarded as estuaries of national conservation importance in South Africa. To provide further insights, sediment samples were acid digested and quantified for metal concentrations using Inductively coupled plasma-optical emission spectrometry (ICP-OES). Multivariate (SIMPROF and cluster) analysis was used to identify how sampling sites in Richards Bay Harbour and Mhlathuze Estuary were grouped based on sediment metal concentrations. Results of pollution load index for Richards Bay Harbour showed site 4 to be heavily polluted, while site 3 in Mhlathuze Estuary showed moderate pollution. Multivariate analysis (SIMPROF and cluster) further revealed sites related to anthropogenic activities and those that were unpolluted. Engaging this advanced analysis enhanced the ability to delineate potential pollution sources and further helped in the identification of the main contributors to sediment pollution. The findings indicate that port and industrial activities are the major contributors to sediment contamination at the estuaries. The results provide specific insights into the sources of pollution, informing targeted environmental management and policy-making efforts to protect and improve the estuarine environments.

Heavy metals and metalloid contamination and risk evaluation in the surface sediment of the Bakkhali River estuary in Bangladesh

Current state of contamination and subsequent risk of contaminated sediment of a tidal river of Bangladesh was evaluated in the present study. Sediment samples were collected from five locations in the tributary of Bakkhali River estuary during summer (April) and winter (December) season, 2020. Collected samples were processed using standard protocol and the content of heavy metals (Cd, Cr, Cu, Pb and Zn) and metalloid (As), were analyzed by the Flame Atomic Absorption Spectrometer. Sediment contamination was evaluated by pollution load index (PLI), contamination factor (CF), degree of contamination (Cd), potential ecological risk index (PERI), non-carcinogenic and carcinogenic risk (CR) due to the dermal contact of the sediment. Multivariate statistical analysis such as principal component analysis (PCA) and cluster analysis (CA) were also applied to find out the possible sources of the contaminant in the sediment. Results showed the average concentration of As, Cd, Cr, Pb, Cu and Zn was 9.74 ± 3.57, 2.00 ± 0.85, 48.75 ± 8.92, 29.78 ± 8.39, 5.44 ± 2.03 and 56.94 ± 8.57 mg/kg, respectively. Concentration of Cu, Pb and Zn were within the recommended level whereas the concentration of As, Cd and Cr were suppressed the recommended level of WHO and FAO/WHO standards. PLI, CF and Cd revealed considerably low degree of contamination of the sediment. Geo-accumulation index indicated uncontaminated to moderately contaminated condition of the sediment. Although the values of enrichment factor revealed no potential enrichment for most of the metals, Cd showed a minor enrichment during the winter season. Based on the ecological risk assessment, the sediment from all of the sample locations was found to be of moderate to low risk. PCA and CA analysis revealed the origin of contaminants mainly from anthropogenic sources. Although different metals showed non-carcinogenic risk to the inhabitants, cancer risk values for dermal contact (CRderm) were much lower than 10−6 indicating no cancer risk for adult and child. However, the findings also revealed that children were more susceptible to CRderm compared to adults. The present study concluded that long term dermal contact of the sediment of Bakkhali River estuary will be contagious to the people. Therefore, regular monitoring of the estuarine environment is necessary so that contamination does not get worse.