Sediments: sink, archive, and source of contaminants

Baseline assessment of metal and microplastic pollution in sediments of a small-sized harbor in western Baltic Sea (Kalmar, Sweden)

This study provides a baseline analysis of sediment pollution in Kalmar Guest Harbor, Sweden, focusing on metals and microplastics. The study site, a bustling coastal area, was chosen to investigate the connections between anthropogenic activities, bioturbation, and environmental contaminants. The results revealed that the pollution extends beyond 30 cm of depth below the seafloor, with elevated levels of copper (Cu), tungsten (W), cadmium (Cd), zinc (Zn), lead (Pb), and microplastics. Significantly, there is no previous publication alarming the W contamination in the Baltic Sea sediment, and therefore, our findings highlight the need for further investigation into tungsten contamination in the region. Furthermore, we explored the distribution patterns, potential sources and relationships of different contaminants. The K-means cluster analysis revealed that bioturbation is speculated to influences the depth concentration of pollutants, particularly at shallow depths (0‬-18 cm). Metal contaminants do not appear to be predominantly bound to MP particles.

Polyhalogenated carbazoles contamination in East China Sea sediments: Spatial distribution, source apportionment, and ecological risk assessment

Polyhalogenated carbazoles (PHCZs), an emerging class of halogenated organic pollutants, have been widely detected in various environmental media, including sediments, soil, air, and organisms. The East China Sea (ECS) is a vital region for marine and fishery resource development in China, yet research on the pollution levels and sources of PHCZs in its sediments remains limited. This study reports the occurrence of seven PHCZs in the surface sediments of the ECS, with detection rates exceeding 90%. The concentrations of Σ7PHCZs ranged from 3.5 to 27 ng/g, with an average of 9.9 ng/g. The predominant congeners were 1368-BCZ and 3-ICZ. The sources of PHCZs included a non-specific source transported via terrestrial runoff (39%), industrial wastewater discharge (35%), and optoelectronic material pollution (26%), as identified by the positive matrix factorization model. The ecological risk assessment, based on TEQ, indicated a range of 0.18-5.0 pg TEQ/g across the study area. These findings highlight the potential ecological concerns associated with PHCZs in the ECS and emphasize the need for enhanced environmental monitoring and source mitigation efforts to reduce their potential environmental impacts.

Assessing sediment contamination status in Important Bird and Biodiversity Areas in Spain

River sediments constitute the physical habitat of aquatic ecosystems and are an important food resource for species and provide a source of life. Yet, sediments are also sinks of chemicals released from the many anthropogenic activities occurring along the river basin. The objective of this study is to determine the presence and risk of 52 legacy and emerging organic pollutants in sediments of 140 Important Bird and Biodiversity Areas (IBAs) located throughout the Spanish territory. In each IBAs, landscape observations including the existence of wastewater treatment plant (WWTP) discharges, picnic areas, landfills, agriculture, industry, urban areas, and human-generated waste (trash) abandoned in nature were recorded and served to determine the main pressures and impact. Sediments were analysed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). The total sum of contaminants in sediments ranged from 0.07 to 31076 ng/g and the most ubiquitous pollutants were polycyclic aromatic hydrocarbons (PAHs), DDTs, and polychlorinated biphenyls (PCBs), while plasticizers and organophosphate esters (OPEs) were detected at the highest concentration, likely due to their recent use and dumping of plastics associated with garbage. Currently used pesticides were seldom detected. The concentrations detected have been compared to sediment quality standards and Predicted No-Effect Concentrations (PNEC) to evaluate the potential risk for the aquatic ecosystem. Risk compounds and pollution hotspots have been identified and mapped. Threshold concentrations are provided to protect habitats and species that live in IBAs, and we highlight the need for sediment monitoring to preserve biodiversity.

Sedimentary co-exposure to bis(2-ethylhexyl) phthalate and titanium dioxide nanoparticles aggravate ecotoxicity and ecological risks through disrupted bioenergetics in Caenorhabditis elegans

Emerging contaminants in estuarine sediments, such as bis(2-ethylhexyl) phthalate (DEHP) and titanium dioxide nanoparticles (nTiO2), pose ecotoxicological risks that may be exacerbated by co-contamination. This study investigated the impacts of DEHP, nTiO2, and their combinations at environmentally relevant concentrations (1, 10, and 100 μg/g) on the soil nematode Caenorhabditis elegans in estuarine-like sediment (14.25‰ salinity). Life history traits and bioenergetics endpoints were examined, with a sample size of ≥ 45 worms or 9 technical repeats per treatment. While individual exposures did not affect growth, the combination of DEHP (1 μg/g) and nTiO2 (100 μg/g) significantly reduced body length by 19%. Single exposure reduced total offspring by 18-41%, whereas the combination of DEHP and nTiO2 synergistically worsened reproductive toxicity (52-74% inhibition), as revealed by Loewe's additivity model and Bliss's independence. DEBtox modeling revealed a shift in physiological mode of action from "increased reproductive costs" in singular exposures to "increased growth and reproductive cost" in co-exposure. Moreover, co-exposure significantly intensified the impacts on bioenergetics-related endpoints, including ATP level (single exposure: 33-34%; co-exposure: 56%), mitochondrial damage (single exposure: 15-17%; co-exposure: 40%), and oxidative stress (single exposure: 5-7%; co-exposure: 13%). Risk quotients based on reproductive toxicity EC10 and DEBtox-derived zb suggested that environmental concentrations of DEHP and nTiO2 pose high risks in global estuarine sediments, with a 2-fold increase during co-exposure. This study demonstrates that co-contamination of DEHP and nTiO2 synergistically aggravates ecotoxicities through disrupted energy allocation, highlighting the importance of assessing mixture toxicity in environmental risk assessment of estuarine sediments.

National scale assessment of the occurrence and risk of trace organic contaminants in Canadian Lake sediments

In Canada studies on the presence of trace organic contaminants (TrOCs) such as pharmaceuticals, personal care products, pesticides and flame retardants in lakes have primarily focused on the water column at localized scales. To address this gap, the occurrence of 44 TrOCs, representative of various types of human activities, was investigated in surface sediments (0-2 cm) from 193 lakes across Canada. A total of 28 targeted TrOCs were detected, with 99.5 % of the samples containing at least one detection, and one lake exhibiting up to 12 detections. The most frequently detected contaminants (> 20 % of samples) were the insect-repellent diethyltoluamide (DEET), the UV filter oxybenzone, the flame retardants tris(2-butoxyethyl) phosphate (TBEP), tris(2-chloroethyl) phosphate (TCEP), and triphenyl phosphate (TPP), the stimulant caffeine, and cotinine, a metabolite of the stimulant nicotine. Median reported concentrations of the targeted TrOCs ranged from 0.017 pg g-1 to 359 ng g-1, with a maximum value of 23,700 ng g-1 observed for DEET in one lake. The geographic distribution of analyte concentrations varied by compound class: pharmaceuticals and consumer product additives were predominantly found in the more urbanized regions of Ontario and Quebec, whereas personal care products such as DEET and oxybenzone were more frequently detected in the western provinces of Canada. An environmental risk assessment based on an additive model conducted on three aquatic organisms (algae, cladocerans, and fish) revealed that 4 % and 6 % of the lakes posed a potentially high risk for cladocerans and algae, respectively. A geographical analysis indicated that lakes in the south of the eastern provinces of Canada presented the highest risks for all three species. These findings represent the first large-scale results detailing the extent of contamination caused by TrOCs on Canadian lake sediments. They establish reference levels that can guide future monitoring efforts and inform policy discussions aimed at protecting lake ecosystems.

Diversity, composition, and assembly processes of bacterial communities within per- and polyfluoroalkyl substances (PFAS)-contained urban lake sediments

Per- and polyfluoroalkyl substances (PFAS) are widespread, highly persistent, and bio-accumulative compounds that are increasingly found in the sediments of aquatic systems. Given this accumulation and concerns regarding the environmental impacts of PFAS, their influence on sedimentary bacterial communities remains inadequately studied. Here, we investigated the concentrations of 17 PFAS in sediments from six urban lakes in Nanjing, China, and assessed their effects on the diversity, composition, potential interactions, and assembly mechanisms of sedimentary bacterial communities. Sediment concentrations of PFAS ranged from 4.70 to 5.28 ng·g-1 dry weight. The high concentrations of the short-chain perfluorobutanesulfonic acid (PFBS) suggested its substitution for the long-chain perfluorooctanesulfonic acid (PFOS). As alternatives to long-chain PFAS, short-chain PFAS had similar effects on bacterial communities. The short-chain perfluoropentanoic acid (PFPeA) and the long-chain perfluorotridecanoic acid (PFTrDA) were the most important PFAS related to the ecological patterns of the co-occurrence network and may alter the composition of the sedimentary bacterial communities in the urban lakes. The Anaerolineaceae family represented as keystone bacteria within the PFAS-affected bacterial co-occurrence network. Deterministic processes (65.9 %), particularly homogeneous selection (63.2 %), were the dominant process driving bacterial community assembly. PFAS promoted the phylogenetic clustering and influenced the community dispersal capabilities to shape bacterial community assembly. This study provides a comprehensive analysis of PFAS distribution in sediments across six urban lakes in Nanjing and provides novel insights into the effects of PFAS on sedimentary bacterial communities. Further research is required to elucidate the mechanisms underlying the impacts of PFAS on microbial communities and to evaluate their broader ecological consequences.

The global issue of metal contamination in sharks, rays and skates and associated human health risks

Elasmobranchs, including sharks, rays, and skates, are a global protein source but face threats from overfishing and population declines. Despite their lower market value, increased consumption raises sustainability and public health concerns. Commonly landed species like the Blue Shark, Shortfin Mako, and Spiny Dogfish are particularly vulnerable to bioaccumulation of metals such as mercury (Hg), lead (Pb), cadmium (Cd), and arsenic (As), posing health risks to consumers. Although metal and metalloid contamination levels in elasmobranchs are frequently reported, studies on specific human health risks remain limited. Sensitive populations, including pregnant women, fetuses, infants, the elderly, and individuals with pre-existing health conditions, face elevated risks from consuming contaminated seafood. Vulnerable communities, especially coastal populations and lower-income groups, encounter further exposure risks due to limited access to safer food alternatives and information. This review explores metal and metalloid contamination in commonly consumed elasmobranch species, associated health risks, and impacts on vulnerable groups, emphasizing the need for informed consumption and the role of contamination awareness in conservation efforts. Arsenic was the most commonly detected element in elasmobranch meat, followed by Se, Hg, Pb, and Cd, with Pb and Se consistently reported at safe levels. Arsenic levels exceeded safety thresholds in most studies, posing health risks, while THQ evaluations indicated significant risks, especially in sharks, where values often surpassed safe thresholds. For C. falciformis, THQ ranged from 5.7 in North America to 38 in Asia, making the consumption of this species inadvisable. Elevated HQ values suggest that cumulative risks likely exceed safe limits, highlighting the need for cautious consumption and further risk assessments.

Emerging organic compounds in surface and groundwater reflect the urban dynamics in sub-Saharan cities

Rapid and uncontrolled urbanization in sub-Saharan Africa has led to an increased production and expansion of synthetic chemicals, resulting in significant pollution of the aquatic environments, particularly by Emerging Organic Contaminants (EOCs). Due to the low income of the population in this region, there is often a lack of control over water and fishery resources prior to consumption. Therefore, the current study aims to use EOCs as markers of water resource quality degradation, and to assess the potential environmental risk of these compounds on some aquatic organisms. Among 120 targeted compounds, 66 were detected at 22 sites in Douala city, Cameroon, including 9 rivers and 13 groundwater samples. The detected EOCs were classified into three categories, including pharmaceuticals and personal care products (n = 55), lifestyle compounds (n = 7) and industrial compounds (n = 4). Surface water was highly impacted, with EOC total concentrations reaching 61,273 ng/L, versus 16,677 ng/L in groundwater. Contamination levels and the type of contaminants were closely linked to land use patterns in the study area. Contamination was mainly attributed to domestic, hospital and brewery's industry wastewaters, landfill and pit latrines. Consumption patterns and physicochemical properties of compounds, in particular their persistence, polarity and octanol/water gradient (Kow), explain their occurrence at high concentrations (up to μg/L) in groundwater. According to Risk Quotient (RQ) with a maximum of 93.4 in surface water and 8.5 in groundwater, about 1/3 of the identified compounds pose a serious threat to aquatic organisms, including algae, invertebrates and fish. For the first time in Central African, we revealed these high levels of water contamination by EOCs and identified the risk for the environmental health. Our study demonstrates the urgency to adopt sustainable water management strategies in large cities of the region.

Basal levels of biochemical biomarkers in the freshwater prawn Palaemon argentinus and their alterations due to the exposure of both insecticides cypermethrin and spirotetramat

The aim of this study was to evaluate the sensitivity of the prawn Palaemon argentinus to the pyrethroid cypermethrin (CYP) and the tetramic acid spirotetramat (STM). These treatments were compared with prawns collected at a reference site to define their basal physiological state. Initially, physicochemical parameters and several pollutants at the selected site were analyzed. The LC50-96 h was determined in adult prawns. Then, prawns were exposed for 96 h to sublethal concentrations of CYP (0.0005 μg/l) and STM (0.44 mg/l) to evaluate the effects on some biochemical endpoints. A treatment combining both pesticides was also added at 5 % of these values. Controls with and without solvent (acetone) were included. The LC50-96 h values were 0.005 μg/l and 4.43 mg/l for CYP and STM, respectively. Moreover, some biomarkers linked to oxidative and energy metabolism were analyzed in the hepatopancreas and muscle of both essayed prawns and those at the basal state. The STM caused a significant decrease in total protein content (32 %) in contrast to the increase of protein carbonyl content (71 %) (p < 0.05). Also, glutathione S-transferase (52 %) and catalase (61 %) activities in the hepatopancreas of exposed prawns were higher compared to both the control and state basal groups (p < 0.05). In muscle, only a significant decrease in the lactate content (69 %) was caused by STM (p < 0.05). In addition, CYP caused a significant increase in the lactate dehydrogenase activity (110 %) in muscle and triacylglycerol content (73 %) in the hepatopancreas (p < 0.05). The integrated biomarker index (IBRv2) analysis showed that STM caused greater damage than CYP. Besides, the combined treatment showed an antagonistic interaction between both insecticides. The differential response of biomarkers to both CYP and STM exposure with respect to their basal levels shows a high sensitivity of P. argentinus demonstrating its potential role as a bioindicator organism.

Occurrence, sources and risk assessment of 12 dioxin-like polychlorinated biphenyls (DL-PCBs) in sediments from the Soummam River protected area, Algeria: A potential threat to the Mediterranean Sea

The levels, the sources and the potential risks associated with twelve dioxin-like PCBs were investigated in the sediments of the Soummam River in northeastern Algeria. Total dl-PCBs concentrations ranged from 3.64 ng/g to 9.38 ng/g with PCB 118 and PCB 105 being the predominant congeners. Principal component analysis suggested that commercial mixtures and municipal waste incineration could be responsible for the presence of PCBs in the region. TEQ values ranged from 12.93 pg/g to 60.98 pg/g indicating adverse effects on aquatic organisms. Moreover, cancer risk assessed via Total Lifetime Cancer Risk (TLCR) suggested that for all the stations, the risk was low but not negligible. Additionally, the non-cancer risk was significant at half of the stations for children but negligible for adults at all the stations. Consequently, measures must be taken by local authorities to protect the environment and the human health.

Levels of potentially toxic and essential elements in Tocantins River sediment: health risks at Brazil's Savanna-Amazon interface

The field study aims to address identified research gaps by providing valuable information on the concentration, spatial distribution, pollution levels, and source apportionment of toxic and essential elements in sediment samples from four sampling sites (P1: Beira Rio (urban area), P2: Bananal (rural area), P3: Embiral (rural area), P4: Cidelândia (rural area) distributed along the middle Tocantins River, Brazil. Samples were collected in 2023 from river sections and analyzed using various contamination índices (geoaccumulation index, contamination factor, enrichment factor, pollution load index, sediment pollution index, potential ecological risk coefficients, and integrated risk index). Results indicated that the levels of aluminum, iron, manganese, and selenium exceeded legal standards in that year. Chromium, nickel, copper, zinc, and lead exceeded guidelines, mainly in section P1 for aluminum and section P3 for nickel and lead. Rainy months showed increased presence, indicating seasonal variability. The geoaccumulation index indicated low pollution levels, with lead and nickel notably present near urban and industrial areas. The enrichment factor highlighted elevated concentrations of lead and zinc in industrial areas. Both PLI and SPI indices raise concerns regarding Pb (P4) and Zn (P3) concentrations at specific times of the year. Overall, potential ecological risks were deemed low for most sites. Continuous monitoring and interventions are crucial to preserve water and environmental quality in the region.

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.

Sediment Toxicity Tests: A Critical Review of Their use in Environmental Regulations

Sediments are an integral component of aquatic systems, linking multiple water uses, functions, and services. Contamination of sediments by chemicals is a worldwide problem, with many jurisdictions trying to prevent future pollution (prospective) and manage existing contamination (retrospective). The present review assesses the implementation of sediment toxicity testing in environmental regulations globally. Currently, the incorporation of sediment toxicity testing in regulations is most common in the European Union (EU), North America, and Australasian regions, with some expansion in Asia and non-EU Europe. Employing sediment toxicity testing in prospective assessments (i.e., before chemicals are allowed on the market) is most advanced and harmonized with pesticides. In the retrospective assessment of environmental risks (i.e., chemicals already contaminating sediments), regulatory sediment toxicity testing practices are applied inconsistently on the global scale. International harmonization of sediment toxicity tests is considered an asset and has been successful through the widespread adoption and deployment of Organisation for Economic Co-operation and Development guidelines. On the other hand, retrospective sediment assessments benefit from incorporating regional species and protocols. Currently used toxicity testing species are diverse, with temperate species being applied most often, whereas test protocols are insufficiently flexible to appropriately address the range of environmental contaminants, including nanomaterials, highly hydrophobic contaminants, and ionized chemicals. The ever-increasing and -changing pressures placed on aquatic resources are a challenge for protection and management efforts, calling for continuous sediment toxicity test method improvement to insure effective use in regulatory frameworks. Future developments should focus on including more subtle and specific toxicity endpoints (e.g., incorporating bioavailability-based in vitro tests) and genomic techniques, extending sediment toxicity testing from single to multispecies approaches, and providing a better link with ecological protection goals. Environ Toxicol Chem 2024;43:1697-1716. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Metal-contaminated sediment toxicity in a highly impacted Neotropical river: Insights from zebrafish embryo toxicity assays

The Fundão dam collapse was one of the largest mining-related disasters globally. It resulted in the release of mining tailings containing heavy metals, which contaminated the Doce River in southeastern Brazil. This study assessed the effects of acute exposure of Danio rerio embryos to sediments contaminated by mine tailings six years after the Fundão dam collapse. The study sites included P2, P3, and P4 in the upper Doce River, as well as site P1 on the Piranga River, an uncontaminated river. Sediment samples were analyzed for 10 metals/metalloid by atomic absorption spectrometry. In the assays, embryos were exposed to sediment from P1-P4 sites, and uncontaminated quartz was used as control sediment. Various biomarkers were applied to assess biological responses, and the integrated biomarker response (IBR) index was calculated for each site. Sediment samples revealed elevated levels of As, Cr, Cu, Hg, and Ni beyond Brazilian legislation limits. At 96-h exposure, embryo mortality rates exceeded 20% in P1, P2, and P3, higher than the control and P4 (p < 0.0001). Hatching rates ranged from 60 to 80% in P1, P2, and P3, lower than the control and P4 (p < 0.001). Larvae exposed to P2 sediment (closest to the Fundão dam) exhibited skeletal, physiological, and sensory malformations. Neurotoxicity was indicated by increased acetylcholinesterase activity and reduced spontaneous movements in embryos exposed to Doce River sediment. Contamination also increased metallothionein and heat shock protein 70 levels, along with changes in cell proliferation and apoptosis. Principal component analysis showed a good correlation between metals/metalloid in the sediment and larval morphometric endpoints. The IBR index highlighted suitable biomarkers for monitoring metal contamination in fish embryos. Overall, our findings suggest that sediment toxicity following the Fundão dam failure may compromise the sustainability of fish communities in the Doce River.

The potential linkage between sediment oxygen demand and microbes and its contribution to the dissolved oxygen depletion in the Gan River

The role of sediment oxygen demand (SOD) in causing dissolved oxygen (DO) depletion is widely acknowledged, with previous studies mainly focusing on chemical and biological SOD separately. However, the relationship between the putative functions of sediment microbes and SOD, and their impact on DO depletion in overlying water, remains unclear. In this study, DO depletion was observed in the downstream of the Gan River during the summer. Sediments were sampled from three downstream sites (YZ, Down1, and Down2) and one upstream site (CK) as a control. Aquatic physicochemical parameters and SOD levels were measured, and microbial functions were inferred from taxonomic genes through analyses of the 16S rRNA gene. The results showed that DO depletion sites exhibited a higher SOD rate compared to CK. The microbial community structure was influenced by the spatial variation of Proteobacteria, Chloroflexi, and Bacteroidota, with total organic carbon (TOC) content acting as a significant environmental driver. A negative correlation was observed between microbial diversity and DO concentration (p < 0.05). Aerobic microbes were more abundant in DO depletion sites, particularly Proteobacteria. Microbes involved in various biogeochemical cycles, such as carbon (methane oxidation, methanotrophs, and methylotrophs), nitrogen (nitrification and denitrification), sulfur (sulfide and sulfur compound oxidation), and manganese cycles (manganese oxidation), exhibited higher abundance in DO depletion sites, except for the iron cycle (iron oxidation). These processes were negatively correlated with DO concentration and positively with SOD (p < 0.05). Overall, the results highlight that aerobic bacteria's metabolic processes consume oxygen, increasing the SOD rate and contributing to DO depletion in the overlying water. Additionally, the study underscores the importance of targeting the removal of in situ microbial molecular mechanisms associated with toxic H2S and CH4 to support reoxygenation efforts in rehabilitating DO depletion sites in the Gan River, aiding in identifying factors controlling DO consumption and offering practical value for the river's restoration and management.

Distribution, levels, sources and risk assessment of polycyclic aromatic hydrocarbons in the bottom sediments of a Mediterranean river under multiple anthropopressures (Soummam River), Algeria

The Soummam River, a vital watercourse in Algeria is threatened by anthropogenic activities despite its protected wetland status. This study is the first to assess sediment pollution in the Soummam River, examining levels, compositions, sources of 16 PAHs and their effects on the environment and human health. Analysis employing Principal Component Analysis (PCA) and molecular diagnostic ratios pointed to petrogenic sources, likely stemming from petroleum leaks originating from aging pipeline and vehicles, as well as pyrogenic sources arising from vehicle exhaust and biomass combustion. Environmental and health risks were assessed through risk quotients (RQ), Sediments Quality Guidelines (SQG) and Total Lifetime Cancer Risk (TLCR). Ecological risk was found to range from moderate to high, with anticipated biological impacts, while cancer risk was deemed low. Toxicity assessment, measured by TEQ, revealed that the majority of monitoring stations exceeded safe levels. Consequently, urgent action by local authorities is warranted to implement ecosystem rehabilitation measures.

Bacterial community in the metal(loid)-contaminated marine vertical sediments of Jinzhou Bay: Impacts and adaptations

Metal(loid) discharge has led to severe coastal contamination; however, there remains a significant knowledge gap regarding its impact on sediment profiles and depth-resolved bacterial communities. In this study, geochemical measurements (pH, nutrient elements, total and bioavailable metal(loid) content) consistently revealed decreasing nitrogen, phosphorus, and metal(loid) levels with sediment depth, accompanied by reduced alpha diversity. Principal coordinate analysis indicated distinct community compositions with varying sediment depths, suggesting a geochemical influence on diversity. Ecological niche width expanded with depth, favoring specialists over generalists, but both groups decreased in abundance. Taxonomic shifts emerged, particularly in phyla and families, correlated with sediment depth. Microbe-microbe interactions displayed intricate dynamics, with keystone taxa varying by sediment layer. Zinc and arsenic emerged as key factors impacting community diversity and composition using random forest, network analysis, and Mantel tests. Functional predictions revealed shifts in potential phenotypes related to mobile elements, biofilm formation, pathogenicity, N/P/S cycles, and metal(loid) resistance along sediment profiles. Neutral and null models demonstrated a transition from deterministic to stochastic processes with sediment layers. This study provides insights into the interplay between sediment geochemistry and bacterial communities across sediment depths, illuminating the factors shaping these ecosystems.

Multiresidue determination and predicted risk assessment of emerging contaminants in sediments from Kongsfjorden, Svalbard

The present work provides the first data on the occurrence of different classes of pharmaceuticals and personal care products (PPCPs) in surface marine sediments from an Arctic fjord (Kongsfjorden, Svalbard Islands, Norway). The target compounds included: ciprofloxacin; enrofloxacin; amoxicillin; erythromycin; sulfamethoxazole; carbamazepine; diclofenac; ibuprofen; acetylsalicylic acid; paracetamol; caffeine; triclosan; N,N-diethyl-meta-toluamide; 17β-estradiol; 17α-ethinyl estradiol and estrone. Sampling was performed in the late summer, when high sedimentation rates occur, and over 5 years (2018-2022). Based on the environmental concentrations (MECs) found of emerging contaminants and the relative predicted no-effect concentrations (PNECs), an environmental risk assessment (ERA) for sediments was performed, including the estimation of the Risk Quotients (RQs) of selection and propagation of antimicrobial resistance (AMR) in this Arctic marine ecosystem. Sediments were extracted by Pressurized Liquid Extraction (PLE) and the extracts were purified by Solid Phase Extraction (SPE). Analytical determination was conducted with liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS). PPCPs were detected in the sediments along the fjord in all the years investigated, with overall concentrations similar in most cases to those reported in urbanized areas of the planet and ranging from a minimum of 6.85 ng/g for triclosan to a maximum of 684.5 ng/g for ciprofloxacin. This latter was the only antibiotic detected but was the most abundant compound (32 %) followed by antipyretics (16 %), hormones (14 %), anti-inflammatories (13 %), insect repellents (11 %), stimulants (9 %), and disinfectants (5 %). Highest concentrations of all PPCPs detected were found close to the Ny-Ålesund research village, where human activities and the lack of appropriate wastewater treatment technologies were recognized as primary causes of local contamination. Finally, due to the presence in the sediments of the PPCPs investigated, the ERA highlights a medium (0.1 < RQ < 1) to high risk (RQ > 1) for organisms living in this Arctic marine ecosystem, including high risk of the spread of AMR.

Polyethylene microplastics induced lipidomic responses in Chironomus tepperi: A two-generational exploration

Microplastics (MPs) accumulating in freshwater sediment have raised concerns about potential risks to benthic dwelling organisms, yet few studies have examined the long-term impacts caused by MP exposure. This study investigated alterations to lipid profiles in an Australian freshwater invertebrate, Chironomus tepperi, induced by polyethylene MP fragments (1-45 μm) at environmentally relevant concentrations (125, 250, 500 and 1000 MPs/kg sediment), using a two-generational experimental design. In the parental generation, the relative abundance of triacylglycerols, total fatty acids and unsaturated fatty acids exhibited apparent hormetic patterns, with low-concentration stimulation and high-concentration inhibition observed. The overall trend in these lipid classes is consistent with previously observed changes to polar metabolite profiles, indicating that ingestion of MPs could inhibit nutrient assimilation from food leading to disruption of energy availability. In the first filial generation continuously exposed to MPs, however, abundance of cholesterol and total fatty acids increased with increasing exposure concentrations, suggesting different effects on energy metabolism between the parental generation and offspring. No differences in the lipidome were observed in first filial larvae that were not exposed, implying that MPs pose negligible carry-over effects. Overall, the combined results of this study together with a preceding metabolomics study provide evidence of a physical effect of MPs with subsequent impacts to bioenergetics. Nevertheless, future research is required to explore the potential long-term impacts caused by MPs, and to unravel the impacts of the surfactant control as a potential contributor to the observed hormetic response, particularly for studies exploring sub-lethal effects of MP exposure using sensitive omics techniques.

Occurrence and partitioning of p-phenylenediamine antioxidants and their quinone derivatives in water and sediment

p-Phenylenediamine antioxidants (PPDs) and PPDs-derived quinones (PPDQs) may pose a threat to the river ecosystem. However, the knowledge on the occurrence and environmental behaviors of PPDs and PPDQs in the natural river environment remains unknown. In this study, we collected paired water (n = 30) and sediment samples (n = 30) from Jiaojiang River, China and analyzed them for nine PPDs and seven PPDQs. Our results showed that target PPDs and PPDQs are frequently detected in water samples, with the dominance of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD; mean 12 ng/L, range 4.0-72 ng/L) and 6PPD-derived quinone (6PPDQ; 7.0 ng/L, Collapse

Key Words

• PPDQs
• PPDs
• Partitioning
• Sediment
• Water

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Affiliation(s)

Jianqiang Zhu Department of Environmental Engineering, Taizhou University, Taizhou, Zhejiang 318000, PR China
Ruyue Guo Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, PR China
Fangfang Ren Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, PR China
Shengtao Jiang Department of Environmental Engineering, Taizhou University, Taizhou, Zhejiang 318000, PR China
Hangbiao Jin Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, PR China; Innovation Research Center of Advanced Environmental Technology, Eco-Industrial Innovation Institute ZJUT, Quzhou, Zhejiang 324400, PR China.

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Stream ecosystem puzzle: understanding how water column and sediment variables shape macroinvertebrate patterns in some Afrotropical streams

Although the interaction of water column and sediment variables in streams is intricate, minimal studies have been conducted on how they influence macroinvertebrate community patterns. This study, therefore, aimed to evaluate the influence of water column and sediment variables on macroinvertebrate community patterns in selected Afrotropical streams. Spatiotemporal scales of water column and sediment variables were analysed following standard methods while macroinvertebrates were sampled using the kick sampling technique. Redundancy analysis (RDA) and variation partitioning were used to assess the relationship of macroinvertebrates with water column and sediment variables. Significant differences were observed between seasons amongst water column variables such as total dissolved solids (p=0.046), turbidity (p=0.027), dissolved oxygen (p=0.011), chemical oxygen demand (p=0.002), bank vegetation (p=0.013), velocity (p=0.04), phosphates (p=0.031), and sediment variables such as total organic matter (p=0.01), pH (p=0.024), electrical conductivity (p=0.014). This accounted for the shift in biotic communities across the two seasons. In the studied area and seasons, Baetidae, Chironomidae, and Thiaridae were the most abundant families of macroinvertebrates representing 21.5%, 17.8%, and 6.9% of the 5266 recorded individuals belonging to 68 families. The water column was the most important predictor of macroinvertebrate community patterns (57%) compared to sediments (35%). Therefore, the use of both water column and sediment variables in ecological studies and biomonitoring should be emphasised because the two compartments provide complementary information. This enables researchers to gain a more complete understanding of the ecological health of aquatic habitats, useful in the development of effective management strategies.

Pesticide residues with hazard classifications relevant to non-target species including humans are omnipresent in the environment and farmer residences

Intensive and widespread use of pesticides raises serious environmental and human health concerns. The presence and levels of 209 pesticide residues (active substances and transformation products) in 625 environmental samples (201 soil, 193 crop, 20 outdoor air, 115 indoor dust, 58 surface water, and 38 sediment samples) have been studied. The samples were collected during the 2021 growing season, across 10 study sites, covering the main European crops, and conventional and organic farming systems. We profiled the pesticide residues found in the different matrices using existing hazard classifications towards non-target organisms and humans. Combining monitoring data and hazard information, we developed an indicator for the prioritization of pesticides, which can support policy decisions and sustainable pesticide use transitions. Eighty-six percent of the samples had at least one residue above the respective limit of detection. One hundred residues were found in soil, 112 in water, 99 in sediments, 78 in crops, 76 in outdoor air, and 197 in indoor dust. The number, levels, and profile of residues varied between farming systems. Our results show that non-approved compounds still represent a significant part of environmental cocktails and should be accounted for in monitoring programs and risk assessments. The hazard profiles analysis confirms the dominance of compounds of low-moderate hazard and underscores the high hazard of some approved compounds and recurring "no data available" situations. Overall, our results support the idea that risk should be assessed in a mixture context, taking environmentally relevant mixtures into consideration. We have uncovered uncertainties and data gaps that should be addressed, as well as the policy implications at the EU approval status level. Our newly introduced indicator can help identify research priority areas, and act as a reference for targeted scenarios set forth in the Farm to Fork pesticide reduction goals.

Uncertainties in Pollution and Risk Assessments of Heavy Metals in Lake Sediments Using Regional Background Soils in China

Background soils are frequently utilized as a surrogate to assess pollution levels and environmental risks of heavy metals in Chinese lakes. However, there remains a lack of understanding regarding the reliability and uncertainty of such assessments. Here, we determined heavy metals (As, Cd, Co, Cr, Cu, Hg, Ni, Pb, and Zn) in sediment cores from five rural lakes in North China to evaluate the reliability and uncertainty of the assessments using background soils by comparing them with assessments based on background sediments. Comparative studies reveal large uncertainties in the assessments using background soils. Among these metals, uncertainties for Hg and Cd are relatively large, whereas those for the other metals are minor. This discrepancy is due to the considerably higher natural variability of Hg and Cd in soils and sediments in comparison to the other metals. Generally, assessments utilizing background soils underestimate pollution levels and risks of Hg but overestimate those of Cd in these lakes. Despite limited human activities around the lakes, they still received a considerable influx of heavy metals via regional atmospheric transport. Assessments of the nine metals indicate moderate to considerable ecological risks in these lakes. The risks are contributed primarily (78-89%) by Hg and Cd. This study underscores the substantial uncertainties in assessing heavy metal pollution and risks using regional background soils and emphasizes the importance of controlling atmospheric emissions of Hg and Cd to mitigate pollution in rural and remote water bodies in China.

Geochemical fractionation, mobility of elements and environmental significance of surface sediments in a Tropical River, Borneo

Miri River is a tropical river in Borneo that drains on flat terrain and urbanised area and debauches into the South China Sea. This paper documents the environmental status of this river, and provides an insight into the provenance using bulk chemistry of the sediments, and brings out the geochemical mobility, bioavailability, and potential toxicity of some critical elements based on BCR sequential extraction. The sediments are intense to moderately weathered and recycled products of Neogene sedimentary rocks. The hydrodynamic characteristics of the river favoured an upstream section dominated by fine sand, while the downstream sediments are medium silt. Based on the bulk geochemistry, the Miri River sediments are moderate to considerably contaminated by Cu, Mo, and As in the upstream and by Sb, As and Cu in the downstream. The potential ecological risk values are low except Cu and a significant biological impact is expected in downstream due to Cu, As, Zn and Cr. The mobility, bioavailability and Risk Assessment Code values for Zn and Mn are higher and thus may pose moderate to very high risk to aquatic organisms. Though a high bulk concentration of Cu is observed, the association of Cu with the bioavailable fraction is low.