Determination of sediment metal background concentrations and enrichment in marine environments - A critical review

Heavy metals contamination in Jakarta Bay sediment: geoaccumulation assessment and implication for environmental health

Heavy metal contamination in marine environments has gained increasing attention due to their accumulation in edible marine organisms, posing potential risks to food safety and human health. This study examines heavy metal contamination in marine sediments from Jakarta Bay, focusing on cadmium (Cd), copper (Cu), iron (Fe), nickel (Ni), lead (Pb), and zinc (Zn). Environmental indices, including the enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (CF), and pollution load index (PLI), were used to assess contamination severity. Average metal concentrations were observed in the order Fe > Zn > Cu > Ni > Pb > Cd, with higher levels near coastal stations, indicating hotspots of pollution. Zn was identified as the primary pollutant, followed by Pb and Cd, likely due to anthropogenic runoff. Comparison with sediment quality guidelines indicated that the contamination poses significant risks to the local marine ecosystem, potentially disrupting biological functions and harming benthic organisms especially near coastal areas. Strong correlations with clay content and Fe suggest that most metals cycle with common geochemical phases, except Ni, which shows a different behavior probably due to its association with the crystalline structure of minerals and potential influences from sediment trapping in deeper areas or long-distance transport.

An insight into sediment fractionation analysis: from sampling to visualisation of results

This review is focused on the importance of operational conditions for metal fractionation and their influence on the results obtained, using both sequential and single step extractions. The discussion is about the different pathways by which metals are incorporated into aquatic systems and the relationship between the nature of sediments and their interaction with metals. In addition, the relevance of the so-called metal extraction methods, either sequential or single-step extractions, to obtain information about the bioavailability and mobility of metals in sediments is considered. Several aspects, such as sampling and sample storage, sediment processing (drying and sieving), sediment mass/extractant volume ratio and operational time, are reviewed since they can significantly affect the recoveries of metals associated with each geochemical phase. Finally, chemometric techniques are addressed as useful tools to visualise and interpret the data obtained and transform them into relevant information. Although a variety of reagents and operating conditions have been used with satisfactory results, there are no standardised protocols, with the exception of the BCR, which has undergone successive modifications. This shows that even the best combination of extractants can have advantages and limitations, and the use of one protocol or another will depend on the type of information required. In this sense, the experimental conditions play a relevant role in obtaining reliable information on the mobility and availability of metals.

Geospatial analysis of trace metal pollution and ecological risks in river sediments from agrochemical sources in Morocco's Sebou basin

Sediments in agricultural ecosystems serve as critical indicators of environmental pollution, particularly in regions subjected to intensive agricultural practices. This research evaluates the environmental hazards and implications of heavy metal (HM) contamination in river sediments from the Sidi Allal Tazi area within Morocco's Sebou basin. Twenty sediment samples were extracted from strategically designated locations, and the contamination levels were analyzed using a multi-index integration approach, multi-statistical analyses (MSA), and Geographic Information Systems (GIS). The results revealed considerable spatial variability in HM concentrations, with Cd and As displaying the highest contamination levels. Statistical analysis, incorporating Principal Component Analysis (PCA), identified anthropogenic activities as the primary contributors to contamination. Hierarchical Cluster Analysis (HCA) categorized metals based on common pollution pathways, while GIS mapping revealed the spatial distribution of contamination across vulnerable areas. Pollution indicators like the Geo-accumulation Index (Igeo) as well as the Pollution Load Index (PLI). revealed that 75% of sites were categorized under "very high pollution", emphasizing the severity of contamination. Contamination Factor (CF) classified 90% of Cd samples and 100% of As samples as "very high contamination". Risk indices indicated significant ecological threats, with Cd contributing to an RI exceeding 600 in many areas, signifying "very high risk". These findings highlight the urgent need for targeted mitigation strategies and sustainable agricultural practices. The integration of multi-index and GIS methodologies provides a comprehensive framework for assessing and managing sediment contamination, offering critical insights for policymakers and environmental managers.

Sediment quality and ecological risk assessment in Mediterranean harbors of Occitanie, France: implications for sustainable dredged material management

The Mediterranean coastal region of Occitanie (France) hosts numerous harbors with economic and touristic activities requiring periodic dredging that may release potentially toxic elements and organic pollutants into the marine environment. Monitoring sediment quality using Sediment Quality Guidelines (SQGs) is essential to assess contamination risks. This study summarizes the geochemical and physical characteristics of sediments from ten harbors of the Occitanie region and evaluates associated ecological risks to inform management strategies. Results are based on measurements required by the French regulation and showed that studied harbors are mostly composed of fine-grained sediments rich in organic matter (32 % on average), those accumulate few contaminants, mainly copper (38-123 mg/kg), zinc (66-156 mg/kg), and lead (15-48 mg/kg), as well as organic pollutants including polycyclic aromatic hydrocarbons (0.23-2.1 mg/kg), and polychlorinated biphenyls (0.05-0.3 mg/kg). Statistical analysis revealed strong correlations between sediment grain size and contaminants distribution. Ecological risk assessment indicated varying but low contamination levels. Copper emerged as the main contaminant, exceeding the threshold effect concentration in 77 % of samples and the probable effect concentration in 5 %. The mean probable effect quotient index suggested moderate ecological risks, with a 33-58 % probability of adverse effects on benthic organisms, emphasizing the need for regular monitoring to prevent potential increases in contamination. Results underlined the interest of adaptive sediment management approach, integrating chemical analyses, bioaccumulation studies, and toxicity testing. While French regulatory thresholds provide disposal guidelines, further studies are needed to refine risk assessments and support sustainable remediation strategies.

Unravelling the anthropogenic pressures in deep waters of the N Iberian Peninsula in the last centuries through the study of sediment cores

The greatest degradation of marine ecosystems has occurred in the last two centuries, coinciding with changes in economic and production models such as the industrialisation. We reconstructed the recent history (last centuries) of marine pollutants (metals and microplastics) in the deep sea of the NW Mediterranean and the Cantabrian Sea (NE Atlantic), analysing 8 sites (cores) at depths between 87 and 1151 m with different levels of terrestrial/oceanic influence. The 210Pb dating showed higher sedimentation rates (MAR) in the upper slope and/or closer to the mainland (0.063-0.078 g/cm2/yr off Barcelona; 0.107 g/cm2/yr in Mallorca at 420 m depth) than in deeper and more open marine stations (MAR = 0.054-0.035 g/cm2/yr), including the Valencia seamount (VS). In terms of metal pollution history, Hg and Pb were good markers of industrial activity, at all stations, including those at 1100-1150 m off Mallorca and on the VS summit. As (arsenic) peaked in the late 19th-early 20th centuries, due to the use of coal as a fuel in steamboats. The role of other metals (e.g. V, Cr, Cd, or Cu) is interpreted locally, depending on the type of industry developed in each area. The rapid and widespread emergence and use of microplastics also made them a good historical marker for sediments. The lithogenic metals Li and Al were good tracers of natural changes (freshwater input, precipitation regime) as their concentration in deep sediments is linked to advective fluxes reaching the seafloor. Both showed a general decline after the middle of the 20th century (1960s), due to a reduction in rainfall and river discharge, as well as an increase in river damming. The observed changes can therefore be explained by a combination of natural variability and the impact of human activities.

Lithogenic and anthropogenic contributions of trace metal(oid)s in coastal sediments near the Port of Trieste (northern Adriatic Sea): A geochemical normalisation approach based on regional background values

Metal(oid) concentrations in coastal sediments are often due to the contribution of anthropogenic inputs to the local geochemistry. This study aims to assess the source (lithogenic or anthropogenic) of metal(oid)s in the surface sediments of the eastern sector of the Gulf of Trieste, which is the area most impacted by urban and industrial activities. A comparison with the environmental quality standards (EQSs) defined by the legislation showed that threshold levels were exceeded for Cr, Ni, Hg, Pb, As and Cd. Since the EQS values do not take into account the natural site-specific geochemical features of sediments, a normalisation procedure was applied to quantify the real anomaly. Aluminium (Al) was identified as an ideal proxy element due to its excellent correlation with the muddy fraction and regional functions for metal(oid)s were determined using sediments from a core collected in the central sector of the Gulf as a baseline in order to calculate enrichment factors (EFs). Negligible or low contamination was found for sediments far from the urbanised and industrialised areas, whereas the EFs were higher near the coast, revealing notable isolated anomalies. The highest enrichment was found for Hg, whose average EF value was 14 times higher than the local baseline, followed by Cu > Cd > Mo > Pb > Zn. On the contrary, Cr and Ni are, in fact, not enriched although showing concentrations higher than the EQS values. This is due to the effectively lithogenic nature of these two elements which occur in the sediments of the Gulf in relation to the particular lithogenic characteristics of the area.

The challenge of establishing natural geochemical backgrounds in human-impacted mangrove soils of Northeastern Brazil

Mangroves are delicate ecosystems constantly pressured by urbanization, pollution, and climate change. Establishing natural geochemical backgrounds (GB) or geochemical baseline levels (GBL) for metals in these soils is challenging due to the dynamic coastal conditions and the combined influence of anthropogenic and natural geological factors. This study aims to establish the natural geochemical background of trace elements in mangrove soils, a more complex task than establishing GBL. A total of 360 soil samples were collected from the mangrove environments of Todos os Santos Bay, Northeast Brazil, specifically from the estuaries of the Jaguaripe, Paraguaçu, and Subaé rivers. The samples were analyzed using handheld X-ray fluorescence spectrometry (XRF), and the data were processed using the Tukey-Inner Fence (TIF) and Cumulative Distribution Function (CDF) methods, with results compared to the multiple regression method based on geochemical data. The Subaé estuary has the highest trace element concentrations, primarily due to its unique geological context, independent of diffuse metal contamination sources. CDF effectively proposed GBL values, providing a comprehensive view of trace element distribution. However, multiple regression outperformed both TIF and CDF methods in managing environmental complexity and modelled precise estimated individual background values, independently of anthropic contamination or variation of soil texture. The predicted background values were 19% and 43% lower than CDF and TIF values, respectively. Some samples showed particularly low modelled background values, up to 75, 25 or 11 times lower than CDF values for V, Mo, Pb respectively. This study enhances the understanding of geochemical dynamics in mangrove estuaries, demonstrating the potential to estimate reliable natural soil backgrounds using advanced statistical methods, even in contaminated and highly changing coastal environments. The findings provide valuable guidelines for assessing and preserving environmental quality in mangrove soils under anthropic pressures.

Application of novel background criteria for assessing metal contamination in sediments of the inner Gulf of Thailand

Establishing a new regional sediment background is crucial for improving the accuracy of assessments of metal contamination and ecological risk in marine environments, ensuring that current data reflects both natural conditions and recent anthropogenic impacts. This study used 210Pb dating techniques to determine new background levels and sediment accumulation rates (SAR) for metals of the inner Gulf of Thailand. Among the 13 sediment cores analyzed throughout the inner Gulf of Thailand, core GT6 was identified as the most representative reference for sediment accumulation in this region. The supported 210Pb level was determined to be .41 ± .04 dpm/g at 25-45 cm depth, indicating equilibrium with natural background levels. A strong exponential decay in the total 210Pb was observed in the upper layers (R2 = .778), and excess 210Pb showed a clear linear decline with depth. The SAR was estimated at .18 cm/year, providing insights into sedimentation processes in the region. The average sediment background concentrations of Al, As, Co, Cr, Cu, Fe, Li, Mn, Ni, Pb, Ti, V, and Zn were 26,479.46, 4.76, 4.14, 21.64, 5.61, 13,733.54, 23.91, 285.44, 15.68, 11.93, 1622.32, 19.16, and 13.11 mg/kg, respectively. Correlation analysis revealed Li to be a better normalizer for Cr, Cu, and Ni, and Ti to be more suitable for normalizing Pb, V, and Zn. This highlights the importance of considering regional characteristics to avoid misinterpreting anthropogenic impacts, making a local approach valuable when sediment quality guidelines are unavailable or unsuitable.

Integrated assessment of heavy metal pollution in the great bačka canal: Comparing active and passive sampling methods

This study investigates the environmental risks posed by heavy metals in sediment from the Great Bačka Canal using both active and passive sampling methods. The necessity of this research lies in the critical need to address sediment contamination in ecological hotspots and enhance sediment management practices. Active sampling revealed total heavy metal concentrations, while sequential extraction showed bioavailability varied across metal fractions. Passive sampling with SPeeper™ quantified freely dissolved metal concentrations in sediment pore water, identifying zinc (41 μg/L) as the most bioavailable metal. Risk indices, including Igeo (geo-accumulation index) and IWCTU (interstitial water criteria toxic units), revealed low to moderate contamination levels. Although copper content classified the sediment as extremely polluted (195.7 mg/kg), its low bioavailability (16 μg/L in pore water) mitigates immediate ecological risks. These findings emphasize the importance of integrating passive sampling in regulatory frameworks for a realistic environmental risk assessment of sediments.

An Over 30-Year Analysis of Heavy Metal Deposition in Daya Bay Sediments

Sediment cores were collected from the nearshore to bay mouth region in Daya Bay, aiming to describe the historical patterns of heavy metals deposition in the sediment. During the last 40 years, the heavy metals exhibited significant different deposition behaviors in the sediment, in which As, Zn, Cr were more enriched and contributed to metals pollution in this area. Moreover, heavy metals deposition exhibited completely opposite behaviors from the nearshore to bay mouth region. An increasing of pollution level and ecological risk was observed in the nearshore, whereas a decreasing trend was detected in the bay mouth. Principal component analysis suggested that heavy metals were possibly derived from anthropogenic activities in the nearshore, whereas natural sources were the main sources in bay mouth. The results indicated the urgency of implementing efficient measures to mitigate heavy metals contamination in the adjacent sea.

Distribution characteristics and ecological risk assessment of heavy metal pollution in seawater near the Yellow River Estuary of Laizhou Bay

To understand the characteristics and pollution status of heavy metals in the intersection areas of Laizhou Bay and the Yellow River Estuary in Shandong Province, the contents of various heavy metals in surface seawater samples collected from this area in August 2022 were detected. The spatial distributions of the heavy metals were analysed, which exhibits a general decreasing trend in the concentrations of Hg, As, Cr, and Pb from west to east, while Cd, Zn, and Cu show the opposite trend. The average single-factor index P values decrease in the following order Pb > Zn > Hg > Cu > As > Cd > Cr, among which Pb, Zn, Hg, and Cu caused pollution in this area. The potential ecological risk index values indicate that the main heavy metal pollutants in study area are Hg and Pb, with Hg having the highest value, accounting for 74.7%, and being the main potential ecological risk factor. Correlation analysis shows that the most significant environmental factor affecting heavy metal content is salinity. According to the interactive heatmap between cluster analysis and station classification, the heavy metals have originated from industrial, agricultural, and domestic sewage discharge, surface runoff, river inputs, seawater aquaculture, maritime transportation, and fuel exhaust emissions. This research hopes to provide some reference value for the protection of marine and estuarine ecosystems.

Environmental degradation and recovery after termination of whaling in sub-Antarctic fjord, South Georgia

Polar ecosystems are considered very fragile, however, due to the short observation record it is hard to assess the recovery processes of the coastal and fjord environments after a major disturbance. Here, we provide a unique case study from South Georgia (sub-Antarctic), an area seriously affected by the whaling industry. The study focuses on King Edward Cove, serving as a sheltered harbor for the former whaling station at Grytviken, as well as other parts of Cumberland Bay considered to represent generally pristine areas. We studied 210Pb dated sediment cores, which were subjected to analysis of sediment geochemical composition, concentrations of anthropogenic organic markers and biomarkers, foraminiferal assemblage changes, as well as sedimentary ancient DNA. Three distinct phases have been identified. The oldest one, predating ca. 1970, recorded the whaling period, and was characterized by anoxic conditions, high organic carbon content, contamination with heavy metals, organic markers, distinct DNA signature and lack of foraminiferal microfossils. It took only a few years to establish a new ecosystem with a fully developed foraminiferal assemblage and decreased contamination characteristic for the middle phase (ca. 1970-2000). Ancient DNA suggests macro-zoobenthic recovery being delayed by a several years in comparison to benthic foraminifera. In the youngest period, around Cumberland Bay, the increase of iceberg rafted debris from rapidly retreating tidewater glaciers was noted, while the improved oxygen availability in bottom waters in King Edward Cove can be likely ascribed to frequent water mixing due to increasing traffic of large cruise vessels. The recorded pace of ecosystem recovery from major anthropogenic disturbance appears similar to that observed in the temperate fjords from the Northern Hemisphere, however, the effects of new anthropogenic threat and the ongoing climate change are already resulting in the new ecosystem disturbance.

Comparative metagenomics highlights the habitat-related diversity in taxonomic composition and metabolic potential of deep-sea sediment microbiota

Sediment plays a pivotal role in deep-sea ecosystems by providing habitats for a diverse range of microorganisms and facilitates the cycling processes of carbon, sulfur and nitrogen. Beyond the normal seafloor (NS), distinctive geographical features such as cold seeps (CS) and hydrothermal vent (HV) are recognized as life oases harboring highly diverse microbial communities. A global atlas of microorganisms can reveal the notable association between geological processes and microbial colonization. However, a comprehensive understanding of the systematic comparison of microbial communities in sediments across various deep-sea regions worldwide and their contributions to Earth's elemental cycles remains limited. Analyzing metagenomic data from 163 deep-sea sediment samples across 73 locations worldwide revealed that microbial communities in CS sediments exhibited the highest richness and diversity, followed by HV sediments, with NS sediments showing the lowest diversity. The NS sediments were predominantly inhabited by Nitrosopumilaceae, a type of ammonia-oxidizing archaea (AOA). In contrast, CSs and HVs were dominated by ANME-1, a family of anaerobic methane-oxidizing archaea (ANME), and Desulfofervidaceae, a family of sulfate-reducing bacteria (SRB), respectively. Microbial networks were established for each ecosystem to analyze the relationships and interactions among different microorganisms. Additionally, we analyzed the metabolic patterns of microbial communities in different deep-sea sediments. Despite variations in carbon fixation pathways in ecosystems with different oxygen concentrations, carbon metabolism remains the predominant biogeochemical cycle in deep-sea sediments. Benthic ecosystems exhibit distinct microbial potentials for sulfate reduction, both assimilatory and dissimilatory sulfate reduction (ASR and DSR), in response to different environmental conditions. The presence of nitrogen-fixing microorganisms in CS sediments may influence the global nitrogen balance. In this study, the significant differences in the taxonomic composition and functional potential of microbial communities inhabiting various deep-sea environments were investigated. Our findings emphasize the importance of conducting comparative studies on ecosystems to reveal the complex interrelationships between marine sediments and global biogeochemical cycles.

Decoupling Sources of Anthropogenic Influences on Sediments of the Visovac Lake (Krka National Park, Croatia) Using Multiparametric Approach

Historical changes of sediment characteristics and levels of inorganic and organic contaminants were studied in dated sediment cores from the Visovac Lake, situated in the Krka National Park, Croatia, to identify the main sources of anthropogenic pressures on this highly protected system. Depth distributions of lithogenic elements showed a steady decrease of terrigenous inputs due to the reduction in agricultural activities in the area, which was particularly pronounced during the 1991-1995 war in Croatia. Vertical and longitudinal distributions of Cd and Zn indicated that they are predominately of anthropogenic origin. The historical profiles of these toxic metals coincide well with the recorded production of metal industry in the upper reach of the Krka River with a sharp decrease reflecting the interruption by the war and slow recovery afterwards. By contrast, the recovery of the tourist industry in Krka NP after the war was accompanied by increasing contamination by elements characteristic of boat and car traffic (Sn, Cu, Pb) as well as oil pollution. The contamination with polycyclic aromatic hydrocarbons and polychlorinated biphenyls was only moderate. Although levels of metallic and organic contamination can be considered relatively low, the observed shift from industrial to tourism-related sources indicated that touristic activities should also be regarded as a possible threat for this vulnerable karst aquatic ecosystem.

Microbial communities as indicators of marine ecosystem health: Insights from coastal sediments in the eastern Adriatic Sea

Considering the adaptability and responsiveness of microorganisms to environmental changes, their indicator potential is still not acknowledged in European directives. This comprehensive study examined the changes of microbial communities in sediments and a range of geochemical parameters from pristine and anthropogenically impacted coastal areas in the eastern Adriatic Sea. Various analytical methods found evidence of sediment contamination (high toxicity level, enrichments of metals, tributyltin) in certain areas, leading to the categorization of sediments based on the level of anthropogenic disturbance. Prokaryotes were identified as the most promising group of microbes for further research, with specific bacterial families (Rhodobacteraceae, Ectothiorhodospiraceae, Cyclobacteriaceae) and genera (Boseongicola, B2M28, Subgroup 23, Sva0485, Thiogranum) proposed as potential indicators of environmental status. Finally, predictive models were developed to identify key indicator variables for assessing anthropogenic impact in sediments. This research represents an essential step toward incorporating microbial communities into assessments of benthic environmental health.

Metal record of copper-based antifouling paints in sediment core following marina construction and operation

Marinas are central hubs of global maritime leisure and transport, yet their operations can deteriorate the environmental quality of sediments. In response, this study investigated the metal contamination history associated with antifouling paint uses in a sediment core collected from Bracuhy marina (Southeast Brazil). Analysis target major and trace elements (Cu, Zn, Pb, Cd and Sn), rare earth elements (REEs), and Pb isotopes. The modification in Pb isotopic ratios and REEs pattern unequivocally revealed sediment provenance disruption following the marina construction. Metal distribution in the sediment core demonstrates that concentrations of Cu and Zn increased by up to 15 and 5 times, respectively, compared to the local background. This severe Cu and Zn contamination coincides with the onset of marina operations and can be attributed to the use of antifouling paints.

Estimation of the level of anthropogenic impact based on the determination of radionuclides and heavy metals in sediments taken from Rybnik reservoir, Poland

The aim of the study was to estimate the degree of anthropogenic risk by evaluating the level of the contamination of sediments collected from the Rybnik reservoir. The results of the determination of radionuclides (137Cs, 40K, 228Th, 228Ra, 226Ra, 210Pb, 238U) and heavy metals (Zn, Cd, Pb, Cu, Cr, Ni) were presented. The Rybnik reservoir is located in a highly urbanised area, the Lower Silesian Voivodeship in Poland. Radionuclides (137Cs, 40K, 228Th, 228Ra, 226Ra, 210Pb, 238U) were measured using gamma spectrometry. The heavy metal (Zn, Cd, Pb, Cu, Ni and Cr) content was determined using an inductively coupled plasma optical emission spectrophotometer (ICP-OES). The classification of sediment pollution was made on the basis of geochemical and ecotoxicological indices. Radioactivity was varied with the highest for 40K (more than 200 Bq·kg-1). The concentrations for the remaining radionuclides were mostly below 20 Bq·kg-1. At the inlet zone (no. 9) an increase in radioactivity of each radioisotope was observed. The values of heavy metals from the lowest to the highest total amount in the sediments were as follows: Cd < Cr < Pb < Ni < Cu < Zn. The sediments of the reservoir are largely contaminated with Cu, but the sediments generally are contaminated to an average degree. Most pollutants accumulate in the inlet zone and near the dam wall. The content of artificial radionuclides, as well as the geochemical and ecological indicators used, can serve as an indicator of the level of anthropopressure in the vicinity of the Rybnik reservoir.

Sediment record of heavy metals in Xincun Lagoon indicating anthropogenic impact over the last 200 years

Anthropogenic metal pollution is a leading environmental problem in southern China, especially in remote regions where its impact remains poorly understood. This study investigates the historical variation of heavy metal pollution over the last 200 years using a sediment core from Xincun Lagoon, Hainan Island, South China. The temporal evolution of heavy metal pollution aligns with China's socioeconomic development. Prior to the 1950s, heavy metal concentrations were at geochemical background levels, reflecting China's agrarian status. Since the 1950s, the increased heavy metal accumulation may be attributed to intensified human activities linked to rapid urbanization and industrialization. Despite the increase in heavy metal enrichments since the 1950s, Xincun Lagoon currently faces a low ecological risk.

Human health risk assessment of metal-contaminated soils in Sydney estuary catchment (Australia)

Sydney estuary catchment supports the largest city in Australia and provides essential eco-social and environmental services; however, the region has been influenced by extensive anthropogenic modification. Soil metal concentrations in the catchment had been studied previously; however, the current investigation was designed to determine the risk posed by these contaminants to human health. Soil metal concentrations were higher than observed in most global capitals and increased substantially in the south and south-east of the catchment and close to the central business district. Road-side soils and road dust contained the highest concentration of metals in the catchment. Lead in catchment soils was closely related to traffic density and sourced from the historic use of Pb in petrol. A human health assessment indicated that soil Cd, Ni and Zn posed no non-carcinogenic risk (NCR), or carcinogenic risk (CR) for children, or adults in Sydney estuary catchment and that Cu and Cr may pose minor NCR for children. Vehicle-related Pb raised the greatest human health risk in catchment soils and may pose NCR at 32% and 4.3% of sites for children and adults, respectively. Inconsistent analytical techniques used in CR and NCR evaluations produce incomparable assessments and a consistent` methodology is suggested to improve interpretation. Human health risk may well be higher than commonly calculated due to pollutants present in urban soil not being included in assessments.

Applying new regional background concentration criteria to assess heavy metal contamination in deep-sea sediments at an ocean dumping site, Republic of Korea

It is crucial to establish appropriate background concentrations to discern heavy metal pollution in the marine environment. In this study, we analyzed heavy metals in deep-sea sediment cores to determine regional background concentrations at the East-Sea Byeong Ocean dumping site. The vertical profiles of heavy metals were categorized into three groups based on their contamination characteristics, and regional background levels for 12 metals were determined using pre-1900 averages. The enrichment factor, contamination factor, and pollution load index, calculated using regional background concentrations, indicated significant contamination by Cr, Co, Cu, Zn, Cd, Hg, and Pb during the ocean dumping period. These results differ from those obtained using global average concentrations. This underscores the importance of considering regional characteristics to minimize the risk of misinterpreting anthropogenic impacts. The approach based on local information is considered useful when sediment quality guidelines are absent or inapplicable.

Spatiotemporal ecological risk evaluation and source identification of heavy metals and nutrients in the water and lake surface sediment in a protected catchment area of a volcanic lake

Indonesia has numerous lakes; however, research on the spatiotemporal sediment quality and source identification in lakes remains limited. The overaccumulation of heavy metals and nutrients in lakes severely threatens aquatic ecosystems. This study aims to identify potential sources of metallic deposits (Cu, Pb, Cr, Fe, Al, and Cd) and nutrients (TN and TP) in lake-surface sediment, utilizing enrichment factors (EF), geoaccumulation indices (Igeo), potential ecological risk indices (Er), and risk indices (RI). Multivariate statistical analyses, including principal component analysis (PCA) and Pearson's correlation analysis, were conducted to pinpoint pollution sources linked to land use. Eight sampling sites for surface sediment and water were examined in both wet and dry seasons at Menjer Lake, chosen for its diverse applications in tourism, hydropower, floating net cages, and extensive agriculture in its catchment. Correlation and PCA results indicated that Pb, Fe, and Al mainly originate from tourism, while Al, Fe, TN, and TP are associated with agriculture. The highest average loading from land use was observed in agriculture (> 0.8), floating net cages (> 0.76), and tourism (> 0.68). Furthermore, the highest loading from nutrients and all metals were TP (> 0.71) and all metals (> 0.35), respectively. Ecological risk assessment revealed low to moderately polluted EFs and Igeo in the dry season. However, Menjer Lake's Er and RI for heavy metals were generally classified as unpolluted.

Trace metals and pesticides in water-sediment and associated pollution load indicators of Netravathi-Gurupur estuary, India: Implications on coastal pollution

Various environmental indicators were used to evaluate the water and sediment quality of the Netravathi-Gurupur estuary, India, for trace metals and pesticide pollution. The descended order of studied metal concentrations (μg/L) in the water was Fe (592.71) > Mn (98.35) > Zn (54.69) > Cu (6.64) > Cd (3.24) > Pb (2.38) > Cr (0.82) and in sediment (mg/kg) was Fe (11,396.53) > Mn (100.61) > Cr (75.41) > Zn (20.04) > Cu (12.77) > Pb (3.46) > Cd (0.02). However, pesticide residues were not detected in this estuarine environment. The various metal indexes categorised the water as uncontaminated, whereas contamination factor, enrichment factor, geo-accumulation index, degree of contamination and pollution load index indicated low to moderate sediment contamination. Multivariate statistics showed that the dominance of natural sources of trace metals with little anthropogenic impact. Improvement in water/sediment quality during the study period might be due to COVID-19 imposed lockdown.

Elemental composition and metal pollution in Egyptian Red Sea mangrove sediments: Characterization and origin

The present work was conducted to characterize the mangrove sediments along the Egyptian Red Sea in terms of elemental composition and to assess the extent of pollution and its sources. A total of 26 samples of mangrove sediments were collected from three different areas: Sharm El Madfea, Sowmaa Mangrove and Abu Fasi. The samples were analyzed using the inductively coupled plasma - mass spectrometry ICP-MS and atomic-emission spectrometry ICP-AES. Mass fractions of a total of 58 major and trace elements were determined in the mangrove samples. Univariate and multivariate statistical analyses were performed to determine the origin of trace and major elements in the mangrove sediments. The normalized values show that the elements above the background can be indicated in descending order as follows: P > Cd > Sr > Ca > U > Se > As > Sn > Cu > Sb > Pb > Mo > Ag. Several pollution indices were also calculated. Principal component analysis revealed three clusters of the studied sediment samples. The analysis of the ratio indicators shows that the origin of the sediments mostly falls near continental island arcs (CIA). The pollution indices show remarkable pollution levels and enriched elements. The data obtained can serve as baseline data for the sediments of the mangrove environment and can be used to study possible changes in the future.

How Biological Activity in Sea Cucumbers Changes as a Function of Species and Tissue

Biological activity and bioactive compound content in sea cucumbers was assessed, considering Parastichopus regalis, Holothuria mammata, Holothuria forskali, and Holothuria arguinensis as species and intestine, muscle band, respiratory tree, body wall, and gonads as tissues. P. regalis had the lowest content in phenolic compounds and antioxidant activity in contrast to Holothuria species. In the respiratory tree, the highest phenolic concentration was recorded in H. arguinensis, 76.4 ± 1.2 mg GAE/100 g dw vs. 21.0-49.0 mg GAE/100 g dw in the other species. H. arguinensis had the highest DPPH and FRAP results in the gonads, 13.6 ± 0.7 mg AAE/100 g dw vs. 2.6-3.5 mg AAE/100 g dw and 27.1 ± 0.3 μmol Fe2+/g dw vs. 8.0-15.9 μmol Fe2+/g dw, respectively. Overall, P. regalis biomass presented the highest anti-inflammatory activity levels and H. arguinensis the lowest anti-inflammatory levels. The respiratory tree was the most anti-inflammatory (measured by the inhibition of cyclooxygenase-2, COX-2) tissue in H. mammata and H. forskali (also the muscle band in this case), 76.3 ± 6.3% and 59.5 ± 3.6% COX-2 inhibition in 1 mg/mL aqueous extracts, respectively. The results demonstrated a variable bioactive potential and advantage in targeting antioxidant properties in the muscle band and anti-inflammatory activity in the respiratory tree, which may constitute a starting point for a biorefinery approach envisaging multiple applications.

Spatial distribution and pollution evaluation in dry riverbeds affected by mine tailings

The objective of this study was to evaluate the level of pollution, sources and potential risk of heavy metals (Zn, Cu, Mn, Cd, Cr, Ni, Fe and Pb) and arsenic (As) in four dry riverbeds affected by mine tailing, which drain into one of the biggest coastal lagoon of Europe (Mar Menor). El Beal, La Carrasquilla, Las Matildes and Ponce dry riverbeds sediments were sampled along its course (20, 18, 13, 19 samples were collected, respectively), and total/soluble metal(loid)s, water soluble ions, nitrogen, and organic/inorganic carbon contents were analyzed. Spatial distribution, principal component analysis (PCA), hierarchical cluster analysis (HCA), contamination factor (Cf), pollution load index (PLI) and potential ecological risk index (RI) were used to identify the possible sources of metal(loid)s and to assess the sediment pollution status. The results showed that the mean total concentrations of As, Cu, Cd, Mn, Zn and Pb exceeded the natural background levels of the study area, with the highest values located close to the mining areas. Correlation and cluster analysis identified that Cd and Zn were associated mainly with anthropogenic activities for all riverbeds, while Cr and Ni come from parent. PLI graded the four riverbeds as contaminated by heavy metals, while RI manifested that 100% of samples located in El Beal, La Carrasquilla and Las Matildes had a significantly high ecological risk. Therefore, this study suggests that mine wastes are the main source of metal(loids) contamination in the dry riverbeds, which results can be used to design actions and measures to reduce the environmental impact of metal(loid)s in the Mar Menor coastal lagoon.

Do the individual and population-level traits of Donax trunculus reflect the effects of metal contamination in aquatic environments?

Heavy metals are considered a major threat to aquatic ecosystems, due to their ability to penetrate and accumulate through the food chain, putting marine organisms and the ecosystem at risk. This research presents a case study of the Taghazout coast, located in the central Atlantic of Morocco, which has become the focal point of various development projects, including the Taghazout Bay tourist resort. The study aimed to gain a deeper understanding of the harmful effects of these metals on the reproductive cycle and population dynamics of the bivalve Donax trunculus. The assessment of cadmium (Cd), lead (Pb), and copper (Cu) levels in D. trunculus bivalves and sediment at the research location provides evidence of exposure to these metal sources by these bivalves. The analysis of the reproductive cycle revealed a balanced sex ratio of males to females. The Sexual Maturity Index (SMI) and Condition Index (CI) of the bivalves were found to be significantly influenced by trace elements Pb and Cu, as well as environmental factors like temperature, dissolved oxygen, and salinity. The maturity stages of the gonads were classified into five stages: undifferentiated, developing, mature, spawning, and spent. Two spawning periods were observed aligning with the population dynamics study that identified a bimodal recruitment (early autumn and spring) in D. trunculus. The population was found to have 11 size cohorts, with a maximum length of 37.96 cm, a yearly growth rate of 1.93 cm, and a short lifespan of 1.5 years. The high mortality rate of 3.30 per year was attributed to the presence of trace elements in Taghazout coast. These findings shed light on heavy metal's impact on the population of D. trunculus, revealing that a sole emphasis on its physiological or cellular effects may overlook its larger impact.

Comparison of spatiotemporal burial and contamination of heavy metals in core sediments of two plateau lakes with contrasting environments: implication for anthropogenic-driven processes

Investigating the impacts of climatic factors and human activities on sedimentary records of heavy metal (HM) contamination in lakes is essential for decision-making in global environmental monitoring and assessment. Spatiotemporal distributions of grain size (GS) and HM (Al, Cr, Mn, Ni, Cu, Zn, As, and Pb) concentrations have been conducted in core sediments that are collected from two adjacent plateau fault-bound lakes in southwest China with contrasting environments, i.e., deep oligotrophic Lake Fuxian (FX) and shallow hypertrophic Lake Xingyun (XY). Results showed that the average value of d50 in FX (4.61 μm) was lower than that in XY (8.35 μm), but the average concentrations of HMs (except Cr and Mn) in XY were higher than those in FX. Heavy metal burial rates (HMBR) were mainly controlled by sediment accumulation rates (SARs) rather than HM concentrations. The correlation coefficients between GS and HM concentrations became strong as the increasing water depths were associated with a stable sedimentary environment. Time-integrated enrichment factors (EF) and source identification of HMs between FX and XY represented that Cr, Ni, and Cu originated from natural sources but Mn, Zn, As, and Pb from anthropogenic sources, respectively. Regardless of FX and XY, the transition times of HMs from natural to anthropogenic sources occurred in the mid-1960s. Comparison of qualification impacts of climatic factors and human-induced factors on increased anthropogenic HMBR by the partial least squares path modeling (PLS-PM) implied that socio-economic activities, such as population density (PD) and gross domestic product (GDP), provided higher contributors to increased anthropogenic HMBR in XY (0.23/0.71) than FX (0.11/0.18). The comparative results of this study provided new insights into environmental monitoring and management of HM contamination for adjacent lakes with contrasting environments.

Benthic foraminifera as proxies for assessing the effects of a pier marina construction: A case study in the naturally stressed environment of the Saco da Ribeira (Flamengo Bay, SE Brazil)

Brazilian coastal areas have been exposed to various anthropic influences including physical alteration such as marina construction. To assess the impact of the pier marina construction in the Saco da Ribeira cove (Flamengo Bay, SE Brazil), sedimentological (grain size), geochemical (organic and trace elements) parameters and benthic foraminifera were analyzed on a 50-cm-long dated sediment core covering the last century. The multiproxy approach applied to a numerical hydrodynamic model shows that the circulation in the study area underwent an overall reduction (ca. 30 %) after the pier marina construction in the 1970s, promoting an increase of mud accumulation and higher concentrations of total organic carbon and trace elements (i.e., Enrichment Factor Cu from 0.80 to 1.4) as well as a shift in the benthic foraminiferal assemblages (i.e., foraminiferal density from 63 to 23.20 specimens per 10 cm3 and dominance from 0.13 to 0.73). On the basis of these integrated data, better environmental conditions occurred before the 1970s, then an overall increase in environmental stress took place after the pier's marina construction. Our results provide a baseline for future biomonitoring projects in a stressed region and exemplify the strong capability and reliability of benthic foraminifera as bioindicators of paleoenvironmental changes in coastal environments and for understanding how human pressure might induce such changes.

Marine Pollution and Advances in Biomonitoring in Cartagena Bay in the Colombian Caribbean

Coastal zones sustain extensive biodiversity, support key processes for ocean dynamics, and influence the balance of the global environment. They also provide resources and services to communities, determine their culture, and are the basis for their economic growth. Cartagena Bay in the Colombian Caribbean is the place of the establishment of one of the country's main cities, which has a great historical and tourist attraction, and it is also the location of the main commercial port and a great variety of industries. Historically, it has been affected by several environmental impacts and intense pollution. This situation has gained the attention of different researchers, so herein is presented a literature review with a systematic approach using RStudio's bibliometrix on the presence of pollutants and the impact on biodiversity in recent decades, providing a critical analysis of the state of Cartagena Bay and its future needs to ensure its recovery and conservation. In addition, the socioeconomic dynamics related to the environmental state of Cartagena Bay are presented from the framework drivers, pressures, status, impacts, and responses (DPSIR). The update and critical understanding of the sources, fate, and effects of pollution are important not only for the knowledge of the status of this singular ecosystem but also to encourage future research and entrench evidence to support decision makers' actions. This review highlights that several pollutants that have been detected exceeding sediment quality guidelines, like As, Cd, Hg, and PAH, are also reported to bioaccumulate and cause damage throughout the trophic levels of the coastal environment. In addition, the potential use of sentinel species and biomarkers for their monitoring is discussed. Finally, the factors that cause pollution and threaten the state of the bay continue to exert pressure and impact; thus, there is a call for the further monitoring of this ecosystem and the strengthening of policies and regulations.

Geochemical controls on the distribution and bioavailability of heavy metals in sediments from Yangtze River to the East China Sea: Assessed by sequential extraction versus diffusive gradients in thin-films (DGT) technique

This study conducted a comprehensive investigation on the distribution and bioavailability of heavy metals (Cr, Co, Ni, Cu, Zn, Cd and Pb) in sediments along two typical transects from Yangtze River to the East China Sea continental shelf that spanning large physicochemical gradients. Heavy metals were mainly associated with the fine-grained sediments (enriched with organic matter), exhibiting decreasing trends from nearshore to offshore sites. The turbidity maximum zone showed the highest metal concentrations, which evaluated as polluted for some tested metals (especially Cd) using the geo-accumulation index. Based on the modified BCR procedure, the non-residual fractions of Cu, Zn and Pb were higher within the turbidity maximum zone, and significantly negatively correlated with bottom water salinity. The DGT-labile metals all positively correlated with the acid-soluble metal fraction (especially for Cd, Zn and Cr), and negatively correlated with salinity (except Co). Therefore, our results suggest salinity as the key factor controlling metal bioavailability, which could further modulate metal diffusive fluxes at the sediment-water interface. Considering that DGT probes could readily capture the bioavailable metal fractions, and reflect the impacts of salinity, we suggest DGT technique can be used as a robust predictor for metal bioavailability and mobility in estuary sediments.

Industrial impacts on vanadium contamination in sediments of Chinese rivers and bays

Vanadium, like many trace metals, is persistent and detrimental to ecosystems at elevated concentrations. Likewise, it is versatile, functional, and used in many industries. Jiaozhou Bay (JZB) and Laizhou Bay (LZB) are valuable coastal ecosystems in China coexisting with several of these vanadium-related industries; however, limited studies have been conducted regarding vanadium occurrence, distribution, sources and risks in sediments. 208 surface sediment samples were collected from rivers and bays over two years and analyzed using inductively coupled plasma optical emission spectrometry. Overall, sediments near vanadium-related industries have significantly higher vanadium concentrations than those near traditional industries, with 30.3% and 22.9% higher average concentrations of vanadium in sediments of JZB and LZB, respectively. Vanadium accumulation at LZB is positively correlated with fine sediment, oxides (e.g., Fe, Ti, Mn), and organic matter content, while temporal changes in parts of JZB highlight the impacts of oxides, pH, and redox conditions on its accumulation. After geochemical normalization, the concentrations in marine samples from LZB showed slightly polluted sediments under the Modified Nemerow pollution index. Likewise, the elevated concentrations of vanadium in JZB, rivers and bay, were classified as slightly polluted and correlated with anthropogenic activities, such as the coal and petrochemical industries. Temporal changes indicated higher enrichments in 2019. Last, humans could be responsible for up to 46.8% and 16.2% of the vanadium accumulation in JZB and LZB, respectively, yet risks to species remain limited.

Available and total phosphorus background levels in soils: a calcareous and semi-arid region

It is critical to understand the risk of element pollution in soils by evaluating their background levels. Phosphorus (P) content in agricultural soils needs to be assessed from agronomic and environmental standpoints. The current study intended to calculate the background levels of available and total P in soils. To achieve this goal, 50 sites without human activities were selected. Soils were sampled from the surface and subsurface of each site (100 soil samples). The available P forms in soils were extracted using the water-extractable P (WEP), calcium chloride-extractable P (CCEP), and Olsen-extractable P (OEP) methods. The first two extractants are being used to evaluate P leaching from soils, while the last one is being used as an agronomic indicator. The methods used to calculate background levels were the iterative 2-δ technique (2-δ) and the calculated distribution function (CDF). Results showed that the upper limits of background levels using 2-δ method were 1.45, 0.92, 8.12, and 424.4 mg kg^-1 for WEP, CCEP, OEP, and total P, respectively. Also, the upper limits of background levels using CDF method were 1.42, 1.15, 12.09, and 447.6 mg kg^-1, for WEP, CCEP, OEP, and total P, respectively. It can be concluded that using these background levels, which for the first time were calculated for P, would enable us to have an accurate examination of P excess as a result of human activities.

Human-induced metals accumulation in sediments of an industrialized bay of northern Chile. An enrichment and ecological risk assessment based on preindustrial values

Environmental assessment in marine systems is difficult because most of the time their preindustrial characteristics are not available. Four sediment cores taken in Mejillones bay (northern Chile) were used to establish preindustrial metals concentrations, and to assess the environmental status of this industrialized zone. According to historical documents, the beginning of the industrial era start in 1850 CE. Considering this, the preindustrial concentration of some metals was established, by mean of a statistical approach. Most of the metals increase their concentration from the preindustrial to the industrial period. Environmental assessment showed an enrichment of Zr and Cr, a moderately polluted condition, and a low probability of toxic effect on the biological communities. The preindustrial values derived from sediment cores are a good tool to evaluate the environmental condition of Mejillones bay. However new information (backgrounds with a higher spatial representativity, toxicological threshold, and others) it is necessary to improve the environmental assessment of this environment.

Metal(oid)s content in High-Andean aquatic systems of the Atacama Desert, Chile: environmental assessment of extreme ecosystems

The high-Andean mountain of northern Chile host numerous water systems that is in risk due to increased mining activities. Total and dissolved Cd, Cr, Cu, Hg, Ni, Pb, Se, and Zn in water, and Cd, Cu, Fe, Ni, Pb, Zn, As, Mo, Al, and V in sediments of 21 aquatic systems (rivers, saline lakes, salt flats), were studied. The presence of Pb, Cd, and As in waters and sediments could be explained, in part, by mining activities. Waters are not suitable for human consumption or irrigation due to high content of Cu and As and high pH that exceed Chilean water quality guideline values. The use of different background reference values influences noticeably the conclusion related to environmental quality of sediments, measured with different environmental indexes. The local geological background suggest that Cd, Mo, Pb, and As generate some degree of contamination, while the use of unpolluted systems as background suggest that all metals measured in sediments represent a low contamination risk. The use of background values of local unpolluted systems seems to be more realistic than geological formation or Upper Continental Crust reference values to assess the environmental condition. The ecological risk assessment suggests that Cd and As are threat for communities living in these aquatic environments. However, these systems support abundant wildlife, developing unique extreme ecosystems with great potential for non-consumptive use such as special interest tourism and conservation.

Assessment of heavy metal pollution in marine sediments from southwest of Mallorca island, Spain

Anthropogenic activities in urban, agrarian, or industrial areas are the main cause of heavy metals in sediments worldwide. Since the 1960s, there have been submarine discharges through outfalls of poorly treated or untreated wastewater on the south coast of Mallorca island (Mediterranean Sea). In this study, the pollution of marine sediments is analyzed at a great number of points on the south of the seacoast. Heavy metal concentrations of As, Ba, Cd, Cr, Cu, Hg, Ni, Pb, Se, V, and Zn, total inorganic carbon (TIC), sulfur, mineralogy, and grain size were analyzed. The objective is to evaluate the concentrations of toxic substances and their spatial distribution and ranges that can negatively affect marine ecosystems and human health. In addition, the results obtained have been compared with standardized indices for marine sediments, and a regional index has been developed with the background values of heavy metals obtained in the sediments of the study area. To obtain consistent conclusions, concentrations of heavy metals were classified with the Igeo Index. The concentrations of heavy metals obtained show that a great number of samples exceeded the limits considered for uncontaminated sediments according to the index applied. Elements such as Hg, Ba, Pb, and Cu showed high concentrations close to the outfalls and lower concentrations in zones far from these points. To support the assessment, chemical processes such as dissolution or chemical precipitation have been studied. The results also show that marine sediments can be a good trap for chemical elements and a good proxy to analyze the impact of anthropogenic activities in areas heavily pressured by humans, and the risk to the environment and human health.

Ecological disturbances and abundance of anthropogenic pollutants in the aquatic ecosystem: Critical review of impact assessment on the aquatic animals

Anthropogenic toxins are discharged into the environment and distributed through a variety of environmental matrices. Trace contaminant detection and analysis has advanced dramatically in recent decades, necessitating further specialized technique development. These pollutants can be mobile and persistent in small amounts in the environment, and ecological receptors will interact with it. Despite the fact that few researches have been undertaken on invertebrate exposure, accumulation, and biological implications, it is apparent that a wide range of pollutants can accumulate in the tissues of aquatic insects, earthworms, amphipod crustaceans, and mollusks. Due to long-term stability during long-distance transit, a number of chemical and microbiological agents that were not previously deemed pollutants have been found in various environmental compartments. The uptake of such pollutants by the aquatic organism is done through the process of bioaccumulation when dangerous compounds accumulate in living beings while biomagnification is the process of a pollutant becoming more hazardous as it moves up the trophic chain. Organic and metal pollution harms animals of every species studied so far, from bacteria to phyla in between. The environmental protection agency says these poisons harm humans as well as a variety of aquatic organisms when the water quality is sacrificed in typical wastewater treatment systems. Contrary to popular belief, treated effluents discharged into aquatic bodies contain considerable levels of Anthropogenic contaminants. This evolution necessitates a more robust and recent advancement in the field of remediation and their techniques to completely discharge the various organic and inorganic contaminants.

Soil and plant contamination by potentially toxic and emerging elements and the associated human health risk in some Egyptian environments

The aim of this work was to assess the origins, mobility, bioavailability and potential health risks of V, Cr, Co, As, Se, Mo, Cd, Sn and Sb, which are not sufficiently studied in the terrestrial environment of Egypt. This has been carried out by employing a combination of chemical fractionation, plants uptake, mathematical modeling and risk assessment approaches on a wide range of soils and plants sampled from industrial, urban and agricultural locations across Egypt. The contents of As, Cd, Sn and Sb were elevated in the soils of some urban and industrial locations within Cairo, although their soil geo-accumulation (I_geo) indices remained ≤ 2, indicating only moderate contamination. Selenium showed moderate to heavy contamination levels (I_geo up to 4.7) in all sampling locations, and Sb was highly elevated (I_geo = 7.1; extreme contamination) in one industrial location. Therefore, Se was the most important contributor to the pollution load followed by Sb and Cd. Both principle component analysis (of total content) and geochemical fractionation (by sequential extraction) suggested that V, Cr and Co are mostly of geogenic origin, while Se and Sb contents appear to be highly influenced by anthropogenic inputs. The most mobile and bioavailable element was Cd with a large non-residual fraction in all soils (76% of total Cd). The bio-concentration factors of Cd in leafy and fruiting plants were 50 times larger than other elements (except Mo) indicating preferential systematic plant uptake of Cd. Risk assessment models showed an overall low noncarcinogenic and carcinogenic risks to the population of Egypt due to the studied elements with only a few anomalies.

Paleolimnological evaluation of metal(loid) enrichment from oil sands and gold mining operations in northwestern Canada

Abundant reserves of metals and oil have spurred large-scale mining developments across northwestern Canada during the past 80 years. Historically, the associated emissions footprint of hazardous metal(loid)s has been difficult to identify, in part, because monitoring records are too short and sparse to have characterized their natural concentrations before mining began. Stratigraphic analysis of lake sediment cores has been employed where concerns of pollution exist to determine pre-disturbance metal(loid) concentrations and quantify the degree of enrichment since mining began. Here, we synthesize the current state of knowledge via systematic re-analysis of temporal variation in sediment metal(loid) concentrations from 51 lakes across four key regions spanning 670 km from bitumen mining in the Alberta Oil Sands Region (AOSR) to gold mining (Giant and Con mines) at Yellowknife in central Northwest Territories. Our compilation includes upland and floodplain lakes at varying distances from the mines to evaluate dispersal of pollution-indicator metal(loid)s from bitumen (vanadium and nickel) and gold mining (arsenic and antimony) via atmospheric and fluvial pathways. Results demonstrate 'severe' enrichment of vanadium and nickel at near-field sites (≤20 km) within the AOSR and 'severe' (near-field; ≤ 40 km) to 'considerable' (far-field; 40-80 km) enrichment of arsenic and antimony due to gold mining at Yellowknife via atmospheric pathways, but no evidence of enrichment of vanadium or nickel via atmospheric or fluvial pathways at the Peace-Athabasca Delta and Slave River Delta. Findings can be used by decision makers to evaluate risks associated with contaminant dispersal by the large-scale mining activities. In addition, we reflect upon methodological approaches to be considered when evaluating paleolimnological data for evidence of anthropogenic contributions to metal(loid) deposition and advocate for proactive inclusion of paleolimnology in the early design stage of environmental contaminant monitoring programs.

Regional background determination and pollution assessment of heavy metals in the semi-closed Bohai Sea sediments

Background metal concentrations are important in assessing pollution level of marine sediments; however, they can be significantly altered by local depositional environments, resulting in significant errors in regional pollution assessment. This study was based on the investigation of the background levels of heavy metals in the Bohai Sea sediments using sediment core, 2-sigma outlier, and regression methods. We also estimate the ecological risks of heavy metals for surface sediments collected from the Bohai Sea using the three methods mentioned above. Ecological risks of heavy metals calculated using the regression method show wide disparities and significant differences from those calculated using the sediment core and 2-sigma methods, indicating that the regression method is not suitable for the Bohai Sea, likely as a result of its complex sources. Conversely, the estimated ecological risks using the sediment core method are moderate, and most heavy metals, except for Hg and Cd, have negligible contamination.

Metal contamination in sediments of dam reservoirs: A multi-facetted generic risk assessment

The quality of bottom sediments is a key factor for many functions of dam reservoirs, which include water supply, flood control and recreation. The aim of the study was to combine different pollution indices in a critical generic risk assessment of metal contamination of bottom sediments. Both geochemical and ecological indices reflected that sediment contamination was dominated by Zn, Pb and Cd. The ecological risk indices suggested a high riks for all three metals, whereas human health risks were high for Pb and Cd. An occasional local contamination of sediments with Cr and Ni was revealed, although at levels not expected to cause concerns about potential ecological or health risk. Sediments from the Rybnik reservoir for Cu only revealed a high potential ecological risk. EF turned to be as being the most useful, whereas TRI (∑TRI) was the most important ecological index. All multi-element indices suggested similar trends, indicating that Zn, Pb and Cd taken altogether had the greatest impact on the level of sediment contamination and posed the greatest potential ecological and health risks to organisms. The use of sequential BCR extraction and ecotoxicity analyses allowed for a multi-facetted generic risk assessment of metals in sediments of dam reservoirs.

Trace metals in urbanized coasts: The central Atlantic of Morocco as a case study

This study describes the contamination, accumulation, and ecological risk assessment of five trace metals (Cd, Pb, Cu, Zn, and Cr) in sediments of an urbanized beach in the central Atlantic coastline of Morocco. The two-year investigation (2018 and 2019) included six sampling sites along a 6 km coastal reach. In both years, none of the studied trace metals exceeded the background or the sediment quality guidelines (SQGs). The eco-toxicological indices revealed low degree of contamination, unpolluted ecosystem, and low ecological risk of metals. However, Cd exceeded the background value and some SQGs following the increase of anthropogenic activities in 2019. Likewise, it indicated unpolluted to moderately polluted sediment as well as moderate ecological risk. Overall, it is highly recommended to mitigate the avoidable anthropogenic activities (marine litter generation, sewage discharge, intense urbanization, and vehicle traffic on the beach) that lead to the elevation of metal pollution in the study area.

Geochemistry of trace metals in surface sediments from the continental slope of the states of Sergipe and Alagoas, Northeastern Brazil

Geochemical analyses were used to determine the origin and identify the main factors that lead to the metal trace distribution on the surface sediments from the continental slope of Sergipe in Brazil. Sediment samples were collected during the dry and rainy periods, from 36 sampling points distributed at water depths from 400 to 3000 m. In general, no effect of seasonality was observed on the metal concentrations and no significant differences were observed between the depth ranges. The correlation analysis indicated the continental origin as the most predominant, followed by authigenic deposition. Anthropogenic enrichment was not noted, nor was the possibility of adverse aquatic biota effects. The results made it possible to understand the contribution of rivers in the transport and transfer of particulate matter to the coastal region, in addition to providing new information on the content of trace metals in tropical Atlantic sediments.

Historical mercury contamination in a major Latin American industrial and port complex: The case of the Santos estuary, Southeastern Brazil

The present study determined total mercury (Hg) in four ²¹⁰Pb dated sediment cores to assess the historical anthropogenic Hg accumulation in the Santos estuary, Southeastern Brazil. Background levels were identified using the deepest sections of the cores, corresponding to pre-industrial ages. Mercury distribution in the sediment cores (0.02-2.64 mg kg^-1) presented a large spatial and temporal variation. Contamination is highest in the upper estuary and indicates that the industrial hub, especially a chlor-alkali plant is the primary source of Hg. A contaminant trap effect is observed in this area associated with high fine sediment accumulation and Hg fluxes. The contamination pattern indicates that the regions not affected by direct inputs are influenced by reworking, resuspension, and transport of contaminated sediments by tidal flows. The Hg enrichment in the upper layers of the sediment cores demonstrates that the environmental actions fulfilled in the 1980s were insufficient to control Hg pollution in the Santos estuary.

Factors driving sediment compositional change in the distal area of the Ria de Vigo (NW Spain): oceanographic processes vs. paleopollution

We analyze potential Late Holocene metal contamination along a sediment core collected in the distal zone of Ria de Vigo (North Spain). Statistical treatment of the dataset based on a multiproxy approach enabled us to identify and disentangle factors influencing the depositional processes and the preservation of the records of this activity in the area over the last ≈3000 years BP. Some layers of the analyzed core have significant enrichment in Cu and a moderate enrichment in Ag, Mo, As, Sb, S, Zn, Ni, Sn, Cd, Cr, Co, Pb, and Li. The enrichment of these elements in some layers of this core may be related to mining activities that have taken place since classical times in the region. Successive phases of pollution were identified along the core KSGX24 related to the Late Bronze Age (≈3000-2450 years BP), Iron Age (≈2450-1850 years BP), Roman times (≈1850-1550 years BP), Middle Ages (≈1250-500 years BP), and industrial and modern (≈250-0 years BP) anthropic activities. The protection of the Cies Islands, the erosive and transport capacity of the rivers in the region, oscillations of the oceanographic and climatic regime, atmospheric contamination, and diagenetic sedimentary processes might have contributed to the accumulation and preservation of this record in the distal region of the Ria de Vigo. The studied core shows that the industrial and preindustrial anthropic impacts caused an environmental liability and contributed to the presence of moderate to heavy pollution of various metals in surface and subsurface sediment layers in the distal sector of the Ria de Vigo, which could be a hazard to biota.

Establishment of background pollution levels and spatial analysis of moss data on a regional scale

The determination of background pollution levels is fundamental for the interpretation of the results obtained from environmental biomonitoring. In this paper we propose a new probabilistic method, based on a Gaussian mixture model, for determining the distribution of regional background levels of different pollutants. The distribution of the reference level is used to categorize the observations as "background" or "above-background" and spatial statistical techniques are then applied to determine the probability of the background level being exceeded. To exemplify its use, we applied the method to concentrations of five potentially toxic elements (Cd, Cu, Hg, Pb and Zn) measured in the moss Pseudoscleropodium purum. The proposed method was applied to data resulting from sampling at ca. 150 sampling stations in a regular grid (15 × 15 km) in Galicia (NW Spain). Sampling was carried out in June in 2000 and 2002, and in March and September in 2004, 2006, 2008 and 2014. The proposed method yielded consistent results for all of the different sampling surveys, and the pollution levels were found to be closely related to the sources of pollution identified in the study region. In short, although not an optimal solution, the proposed method seems to be suitable and realistic for the qualitative assessment of regional pollution.

A 140-year record of environmental changes in São Sebastião, Brazil

Over the past two centuries, coastal and estuarine areas have experienced environmental stress due to rapid population growth, leading to higher demand, overexploitation, habitat transformation, and pollution, which have severe consequences on the overall ecosystem and human health. This work aims to understand historical perspectives of such environmental stress in a coastal area of São Sebastião city in the São Paulo State of Brazil, which has witnessed rapid changes in land use over the past 60-70 years. We collected eleven surface sediments and one 64 cm long core from the shallow water depth sector of the São Sebastião Channel (SSC), adjacent to the Araçá Bay region. Sediments were dominantly composed of terrestrial siliciclastic material carrying signatures of both local inputs (i.e., weathered granitic and gneissic rocks of Serra do Mar Mountain ranges) and Plata Plume sediments brought by Brazilian coastal currents. Low sediment accumulation (avg. = 0.10 cm yr^-1) between 1880 and 1947 showed a stable environment followed by an abrupt increase in sedimentation (avg. = 0.84 cm yr^-1) from 1947 to 2017. This approximate eight-fold increase in sedimentation after 1947 marked significant anthropogenic changes in the region, which is coincidental with major changes in land use through the construction of the port of São Sebastião (1930s) and BR-101 Highway (1980s). While recent surface sediments showed no pollution of heavy metals, anthropogenic Zn enrichment was found between 1880 and 2000. Zn enrichment was from the combined sources, e.g., agriculture activities, domestic sewage, and possibly Zn coated ship paints. Our study also indicates that planned future expansion of São Sebastião port may further increase the sedimentation rate in SSC and impact the ecosystem of Araçá Bay and SSC.

Integrating indices based on different chemical extractions and bioaccumulation in Bellamya aeruginosa to assess metal pollution and ecological risk in sediment

Various indices based on metal chemical data are used to evaluate pollution and ecological risk, but the consistency of the assessment results is usually unsatisfactory, and it is unclear if the ecological risk from sediment metals is accurately represented in in situ zoobenthos. Herein, the pollution and ecological risk associated with As, Cd, Cr, Cu, Ni, Pb and Zn in the sediments of two adjacent lakes (Datun (DT) and Changqiao (CQ)) were comprehensively evaluated by integrating metal concentrations, chemical forms and bioaccumulation in Bellamya aeruginosa (B. aeruginosa). The metal concentrations and chemical compositions varied widely in the sediments. Over 50% of the Cd, Pb and Zn in the sediments was present in bioavailable forms, followed by 28% of Cu and less than 25% of As, Cr and Ni. According to the enrichment factor (EF) and concentration enrichment ratio (CER) assessments, Cr and Ni were natural in origin, while the other metals were at minor to extremely high pollution levels, with average EFs of 1.5-77.6 and CERs of 1.1-113.4. The pollution levels for Cd, Cu and Pb from the EF and CER assessments were similar, while those for As and Zn were higher according to CER than EF (p = 0.05), likely due to the baseline underestimation associated with the potential diagenetic remobilization of bioavailable metals. The ecological risk index (Er), sediment quality guidelines (SQGs) and risk assessment code (RAC) showed a high eco-risk for Cd, while no similar risk was found for the other metals. By integrating risk indices with the chemical forms and pollution levels of metals, we deduced high eco-risks for As and Pb and moderate eco-risks for Cu and Zn in DT Lake and moderate eco-risks for As, Pb and Zn in CQ Lake. The other metals in the sediments of the two lakes presented low eco-risks. No significant positive correlations (p = 0.05) between metal accumulation in B. aeruginosa and the indices of pollution and eco-risk were observed except for the case of As, implying that measuring the metal concentrations in B. aeruginosa would not accurately characterize the metal pollution and ecological risk of sediments.