Trophic Magnification of Organic Chemicals: A Global Synthesis

Bioaccumulation and Trophic Transfer of Organophosphate Esters (OPEs) in Arctic Terrestrial and Benthic Marine Ecosystems

The increasing prevalence of organophosphate esters (OPEs) in remote polar ecosystems has raised significant concerns; yet the bioaccumulation and trophic transfer dynamics of these compounds in polar regions remain poorly understood. This study investigated the occurrence and distribution of OPEs in soil, vegetation, marine sediment, and biota from Svalbard, Arctic. Σ10OPEs ranged from 1.12 to 236 ng/g dry weight (dw) and 1.96 to 255 ng/g dw in the Arctic terrestrial and benthic marine matrices, respectively. Triethyl phosphate (TEP), tris(1-chloro-2-propyl) phosphate (TCIPP), tris(2-chloroethyl) phosphate (TCEP), and tri-(2-butoxyethyl) phosphate (TBOEP) were the dominant congeners across all samples. OPEs exhibited bioaccumulation within the soil-vegetation system of the terrestrial environment, while significant trophic dilution occurred in the benthic marine food web. Interestingly, parabolic correlations were observed between log octanol-water partition coefficients (log KOW) and log-transformed bioconcentration factors (BCFs) in the terrestrial environment, as well as between log KOW and trophic magnification factors (TMFs) in the benthic marine food web, suggesting that congeners with moderate lipophilicity exhibit the highest potential for bioaccumulation. This study presents the first comprehensive assessment of the bioaccumulation and trophic transfer of OPEs in the Arctic ecosystem, providing critical insights into the environmental behaviors of OPEs in polar regions.

Integrating the Bright and Dark Sides of Aquatic Resource Subsidies-A Synthesis

Aquatic and terrestrial ecosystems are linked through the reciprocal exchange of materials and organisms. Aquatic-to-terrestrial subsidies are relatively small in most terrestrial ecosystems, but they can provide high contents of limiting resources that increase consumer fitness and ecosystem production. However, they also may carry significant contaminant loads, particularly in anthropogenically impacted watersheds. Global change processes, including land use change, climate change and biodiversity declines, are altering the quantity and quality of aquatic subsidies, potentially shifting the balance of costs and benefits of aquatic subsidies for terrestrial consumers. Many global change processes interact and impact both the bright and dark sides of aquatic subsidies simultaneously, highlighting the need for future integrative research that bridges ecosystem as well as disciplinary boundaries. We identify key research priorities, including increased quantification of the spatiotemporal variability in aquatic subsidies across a range of ecosystems, greater understanding of the landscape-scale extent of aquatic subsidy impacts and deeper exploration of the relative costs and benefits of aquatic subsidies for consumers.

Multi-cascade physiologically based kinetic (PBK) matrix model: Simulating chemical bioaccumulation across food webs

In modern ecosystems, many substances that biomagnify within food webs adversely affect organisms and ecological systems. To facilitate high-throughput screening of contemporary chemicals, we developed a multi-cascade physiologically-based kinetic (PBK) matrix model to simulate bioaccumulation and biomagnification along food chains. The model's validity is supported by the mean model bias (MB) values, which fall within the acceptable range when compared with measured biomagnification factors (BMFs) reported in the literature. Analyzing 3,074 organic chemicals, we estimated their biotransfer factors (BTFs)-the steady-state ratio of chemical concentrations in primary consumer tissues to those in their feed-and their BMFs-the steady-state ratio of chemical concentrations in predators to their prey. Our results reveal consistent BTF trends across different tissues within the same species for a given chemical. Chemicals with moderate lipophilicity and low diffusivity tend to be retained longer in organisms, leading to higher BMFs. Notably, mammals appear particularly sensitive to persistent organic pollutants, while birds and ectothermic species do not exhibit clear patterns. Overall, the study highlights that animal physiological parameters and chemical physicochemical properties are more critical in determining bioaccumulation and potential toxicity than an organism's trophic position. Future research should refine key physiological parameters, such as hepatic metabolic rate constants, account for life-stage variations, and evaluate multiple exposure pathways to further enhance model accuracy and real-world applicability.

Distinct trophic transfer of rare earth elements in adjacent terrestrial and aquatic food webs

Growing demand and usage of rare earth elements (REEs) lead to significant pollution in wildlife, but trophic transfer of REEs in different food webs has not been well understood. In the present study, bioaccumulation and food web transfer of 16 REEs (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, and Sc) were investigated in different terrestrial and aquatic species. Median concentrations of REEs in plant, invertebrate, fish, amphibian, reptile, bird, and vole samples were 488-6030, 296-2320, 123-598, 17.5-88.1, 88.0, 14.2-92.0, and 170 μg/kg, respectively. The REE concentrations decreased as plants > invertebrates > fishes > amphibians and snakes > birds. The biomagnification factors (BMFs) and trophic biomagnification factors of most REEs were lower than 1, indicating trophic dilution of REEs. Most poikilotherms including fishes, amphibians, and snakes presented higher BMFs of REEs than homotherms including birds and voles (p < 0.05). Negative correlations were observed between REE concentrations and δ13C (p < 0.01), not δ15N (p > 0.05) in terrestrial organisms, while REE concentrations were negatively correlated with δ15N (p < 0.05), not δ13C (p > 0.05) in aquatic organisms. The result implies diet source and trophic level as key factors affecting the cycling of REEs in terrestrial and aquatic food webs, respectively.

Bioaccumulation and potential human health risks of PAHs in marine food webs: A trophic transfer perspective

Polycyclic aromatic hydrocarbons (PAHs) are persistent pollutants in aquatic environments that can accumulate in marine organisms and pose potential health risks to humans through trophic transfer in the food webs. However, the accumulation and health risks of PAHs in organisms at different trophic levels remain unclear. This study investigated the accumulation and trophic transfer of PAHs in 40 marine organisms from Beibu Gulf (China), and assessed their health risks. Utilizing the trophic level spectrum constructed with stable isotope methods, the organisms were categorized into three trophic levels: Omnivorous (15.00 %), low-level carnivorous (67.50 %), and mid-level carnivorous (17.50 %). The contamination levels of total PAHs in these organisms ranged from "mild pollution" to "moderate pollution", with all organisms exhibiting significant PAH accumulation (Bioconcentration factor value > 2000). Total PAH concentrations increased with higher trophic levels, following the trend of mid-level carnivores > low-level carnivores > omnivores. Notably, only three PAH compounds (Nap, Fla and Phe) showed biomagnification effects, while the others exhibited trophic dilution. Carcinogenic risk assessment indicated an "Unacceptable risk" level for all populations, with the highest risk due to consumption of mid-level carnivorous. These findings offer new insights into the accumulation and health risks of PAHs from a trophic transfer perspective.

Persistent, bioaccumulative, and toxic pollutants in migratory waterbirds from Bohai Bay, China: Implications on distinct pollutant sources

Bohai Bay is an important stopover on the East Asian-Australasian flyway (EAAF) for migratory birds. In the present study, eggs of three migratory waterbird species, Little Terns (Sterna albifrons), Pied Avocets (Recurvirostra avosetta), and Black-winged Stilts (Himantopus himantopus), and local aquatic organisms from Bohai Bay (Nanpu and Dongying wetlands) were collected to determine stable isotope (13C, 15N, D) signature and concentrations of mercury (Hg), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDTs), and short-chain chlorinated paraffins (SCCPs). Organisms from Nanpu had significantly higher δD values than Dongying, which was related to local salinity. The pollution profiles showed species-specific difference in the same site, but no spatial difference for the same bird species from two wetlands. Positive correlations were observed between δ15N values and concentrations of Hg and PCBs, but not DDTs and SCCPs, because of the complex pollution sources in migration routes. The pollution exposure in the annual life cycle for Pied Avocets based on migration route information suggests that Hg and PCBs in eggs mainly originate from the breeding site (Bohai Bay), while DDTs are mainly from the wintering sites (the middle and lower reaches of the Yangtze River). Pollutants could pose considerable negative effect on eggshell thickness. The present study promotes the importance of pollutant exposure and risk assessment in the entire migration cycle for migratory birds.

Global occurrence, food web transfer, and human health risks of polycyclic aromatic hydrocarbons in biota

Polycyclic aromatic hydrocarbons (PAHs) are widespread organic pollutants that pose significant health risks due to their bioaccumulation in the biota. This study examines the global distribution of PAHs in biota, identifies key factors influencing using boosted regression tree (BRT) models, analyzes their transfer through trophic magnification factors (TMF), and evaluates health risks using the EPA risk assessment model. Research on PAHs has grown from 1978 to 2023, peaking in 2021, with 171 out of 241 studies (71.1 %) focusing on marine ecosystems. The highest PAH concentrations are observed in the Mediterranean Sea, Red Sea, and North American coastal regions, primarily influenced by industrial and human activities, such as factory emissions and ship transport. BRT analysis shows region factors and feeding habitats significantly influence PAH levels. TMF analysis shows that biodilution is the main mechanism for PAH attenuation, with concentrations decreasing as trophic levels increase. Additionally, health risk assessment further illustrate that toxicity equivalent (TEQ) values are highest in Egypt and Turkey. Across all populations in Egypt, the United States, Turkey, Portugal, and China, as well as children in Portugal and Sweden, there are potential risks from aquatic product consumption (10-6 < CRI < 10-4), with CRI values positively correlated with liver cancer incidence. While hazard quotients (HQ) < 1 suggest overall safety, higher obesity risks are noted, particularly among women and adolescents.

The trophodynamics of polycyclic aromatic hydrocarbons in marine food webs: The importance of trophic level span from insights into Liaodong Bay (China)

The occurrence and trophic transfer of polycyclic aromatic hydrocarbons (PAHs) in aquatic ecosystems is vital to assess ecological risks. PAHs concentrations were analyzed in seawater, sediment, plankton, and marine species (15 fish species, 8 invertebrate species, 3 marine mammals), collected from Liaodong Bay (China). Bioaccumulation and biomagnification were calculated to demonstrate the biotransfer pattern of PAHs from the environmental matrix to high-level predators through the food web. Total PAHs concentrations ranged from 81.2 to 197.6 ng/L in seawater, 51.4-304.8 ng/g (dw) in sediment, and 65.3 to 28,885 ng/g (lw) in all biota samples. Three- and four-ring PAHs constituted major components (>81% in each case) of PAH congener profiles. Lower biota-sediment accumulation factors (BSAFs) and bioaccumulation factors (BAFs) values indicated limited bioaccumulation of PAHs within marine organisms. Also, 77% of biomagnification factors (BMFTL) values of PAHs in spotted seal and finless porpoise were >1, whereas opposite transfer patterns of PAHs were observed in food webs with trophic values of 1.5-3.5 and 3.0-4.0; that is, trophic dilution (trophic magnification factor (TMF) < 1) and trophic magnification (TMF >1), respectively. This study provides novel insights into the importance of TL span for trophodynamics of PAHs within food webs.

Food web bioaccumulation model for ecological risk assessment of emerging organic pollutants in marine ecosystems: Principles, advances and challenges

The bioaccumulation and trophic transfer of pollutants in marine ecosystem members determine their ultimate ecological risks. Food web bioaccumulation models are widely used in scientific and regulatory programs to assess the bioaccumulation and ecological risks of pollutants at the ecosystem scale. The food web models are mainly established through concentration- and fugacity-based modeling approaches and include some chemical, food web-related, physiological and environmental factors. The models applied in the "forward approach" predict bioaccumulation and conduct internal exposure level-based ecological risk assessment (IEL-ERA), whereas those in the "reverse approach" are used to back-calculate the IEL-based predicted no-effect concentrations (PNECs) or environmental criteria. However, some challenges still exist in the application of food web model integrated risk assessment, including the lack of standardized/generalized frameworks, the lack of chemical- and species-specific toxicokinetic data and internal exposure (or tissue residue)-based toxicity data, and the lack of uncertainty-control methods in model estimation and parameterization. There are urgent requirements to improve models, integrate methods and update study designs in the assessment and prediction of "system-scale risks" of marine emerging organic pollutants.

Trace organic contaminants in U.S. national park surface waters: Prevalence and ecological context

Surface water samples were collected from 264 sites across 46 U.S national parks during the period of 2009-2019. The number of sites within each park ranged from 1 to 31 and the number of samples collected within each park ranged from 1 to 201. Samples were analyzed for up to 340 trace organic contaminants (TrOCs), including pharmaceuticals, personal care products, pesticides, and various contaminants indicative of anthropogenic influence (e.g., fragrances, surfactants, flame retardants). A total of 155 TrOCs was detected in at least one sample with concentrations ranging from the reporting level of 10 ng/L (multiple contaminants) to 11,900 ng/L (p-cresol). Except for bisphenol A, DEET, theobromine, and gabapentin, TrOCs were detected in <20% of samples. Despite the relatively low detection frequencies, when TrOCs were detected, concentrations were similar to those reported from other regional or national studies. We compared detected concentrations to bioactivity concentrations and water quality benchmarks, when available, to identify occurrences of elevated concentrations and to estimate the potential for biological effects to aquatic biota. Elevated concentrations of 27 TrOCs, mostly pesticides, were detected throughout the study. To gain insight regarding potential sources, we related watershed characteristics (e.g., land cover, presence of point sources) to the number of TrOCs detected at each site. We found that the presence of wastewater treatment plants and the proportion of the watershed classified as agricultural land were the most influential variables for describing the number of pharmaceuticals and the number of pesticides present, respectively. This study represents the largest-scale study characterizing the presence and magnitude of TrOCs in U.S. national park surface waters, to date. These data provide a baseline that can be used to inform future monitoring within the parks and to assess changes in water quality.

From Trophic Magnification Factors to Multimedia Activity Ratios: Chemometers as Versatile Tools to Study the Fate of Hydrophobic Organic Compounds in Aquatic Ecosystems

We applied passive equilibrium sampling using silicone-based chemometers to nine biota species, sediment, and water in a multimedia aquatic ecosystem. They allowed for direct comparison of the concentration of regulated and emerging hydrophobic organic compounds in the silicone across species as well as the comparison of biota with sediments and water. We derived chemometer-based trophic magnification factors (TMFs) of diverse compounds that agreed with the traditionally derived TMFs. Our exploratory work in water demonstrated that equilibrium with newly designed chemometers can be achieved in few days for compounds with a log KOW up to 6. We calculated activity ratios, dividing the concentrations in the silicone equilibrated with biota by those equilibrated with the abiotic exposure media (sediments and water), assessing the thermodynamics of bioaccumulation and the equilibrium state between the ecosystem compartments. They confirmed that the biota were below equilibrium partitioning relative to sediments and water, as other studies have described. Silicone-based chemometers open up new opportunities and applicability in multimedia aquatic ecosystems for studies that rely on equilibrium partitioning of the in-situ mixtures of chemicals, such as multimedia assessments or application of effect-based methods.

The persistent DDT footprint of ocean disposal, and ecological controls on bioaccumulation in fishes

Globally, ocean dumping of chemical waste is a common method of disposal and relies on the assumption that dilution, diffusion, and dispersion at ocean scales will mitigate human exposure and ecosystem impacts. In southern California, extensive dumping of agrochemical waste, particularly chlorinated hydrocarbon contaminants such as DDT, via sewage outfalls and permitted offshore barging occurred for most of the last century. This study compiled a database of existing sediment and fish DDT measurements to examine how this unique legacy of regional ocean disposal translates into the contemporary contamination of the coastal ocean. We used spatiotemporal modeling to derive continuous estimates of sediment DDT contamination and show that the spatial signature of disposal (i.e., high loadings near historic dumping sites) is highly conserved in sediments. Moreover, we demonstrate that the proximity of fish to areas of high sediment loadings explained over half of the variation in fish DDT concentrations. The relationship between sediment and fish contamination was mediated by ecological predictors (e.g., species, trophic ecology, habitat use), and the relative influence of each predictor was context-dependent, with habitat exhibiting greater importance in heavily contaminated areas. Thus, despite more than half a century since the cessation of industrial dumping in the region, local ecosystem contamination continues to mirror the spatial legacy of dumping, suggesting that sediment can serve as a robust predictor of fish contamination, and general ecological characteristics offer a predictive framework for unmeasured species or locations.

Biomagnification potential and health risks of organophosphate esters in prey to humpback dolphins based on dietary correction

Information on the biomagnification of organophosphate esters (OPEs) is limited, and the results are inconclusive, mainly because precise predatorprey relationships have not been determined. Herein, we first evaluated the biomagnification potential and dietary exposure risk of 15 OPEs in 14 prey species (n = 234) to Indo-Pacific humpback dolphins from the northern South China Sea using quantitative fatty acid signature analysis (QFASA). QFASA identified Chinese gizzard shad as the primary prey of dolphins. Among the 15 OPEs, 86.7 % (13/15) had a diet-adjusted biomagnification factor (BMFQFASA) greater than 1, indicating the biomagnification potential between dolphins and their diet. Moreover, BMFQFASA exhibited a considerable positive correlation with the log octanolwater partitioning coefficient of OPEs, indicating that lipophilicity may affect the bioamplification of OPEs. Risk assessments showed that although current OPE levels may not pose substantial health risks to dolphins via diet intake, the nondiet-adjusted hazard quotient/hazard index underestimated the exposure risk of OPEs to this vulnerable dolphin species. This study provides novel evidence regarding the biomagnification and dietary exposure risks of OPEs in cetaceans, emphasizing the importance of estimating the dietary composition of predators in such analyses.

Continental-scale nutrient and contaminant delivery by Pacific salmon

The movement of large amounts of nutrients by migrating animals has ecological benefits for recipient food webs1,2 that may be offset by co-transported contaminants3,4. Salmon spawning migrations are archetypal of this process, carrying marine-derived materials to inland ecosystems where they stimulate local productivity but also enhance contaminant exposure5-7. Pacific salmon abundance and biomass are higher now than in the last century, reflecting substantial shifts in community structure8 that probably altered nutrient versus contaminant delivery. Here we combined nutrient and contaminant concentrations with 40 years of annual Pacific salmon returns to quantify how changes in community structure influenced marine to freshwater inputs to western North America. Salmon transported tonnes of nutrients and kilograms of contaminants to freshwaters annually. Higher salmon returns (1976-2015) increased salmon-derived nutrient and contaminant inputs by 30% and 20%, respectively. These increases were dominated by pink salmon, which are short-lived, feed lower in marine food webs than other salmon species, and had the highest nutrient-to-contaminant ratios. As a result, the delivery of nutrients increased at a greater rate than the delivery of contaminants, and salmon inputs became more ecologically beneficial over time. Even still, contaminant loadings may represent exposure concerns for some salmon predators. The Pacific salmon example demonstrates how long-term environmental changes interact with nutrient and contaminant movement across large spatial scales and provides a model for exploring similar patterns with other migratory species9.

Water temperature governs organophosphate ester dynamics in the aquatic food chain of Poyang Lake

Organophosphate esters (OPEs) are increasingly recognized as pervasive environmental contaminants, primarily from their extensive application in flame retardants and plasticizers. Despite their widespread presence, the intricacies of OPE bioaccumulation within aquatic ecosystems remain poorly understood, particularly the environmental determinants influencing their distribution and the bioaccumulation dynamics across aquatic food chains. Here we show that water temperature plays a crucial role in modulating the dispersion of OPE in the aquatic environment of Poyang Lake. We quantified OPE concentrations across various matrices, uncovering levels ranging from 0.198 to 912.622 ng L-1 in water, 0.013-493.36 ng per g dry weight (dw) in sediment, 0.026-41.92 ng per g wet weight (ww) in plankton, 0.13-2100.72 ng per g dw in benthic invertebrates, and 0.31-3956.49 ng per g dw in wild fish, highlighting a pronounced bioaccumulation gradient. Notably, the intestines emerged as the principal site for OPE absorption, displaying the highest concentrations among the seven tissues examined. Among the various OPEs, tris(chloroethyl) phosphate was distinguished by its significant bioaccumulation potential within the aquatic food web, suggesting a need for heightened scrutiny. The propensity for OPE accumulation was markedly higher in benthic invertebrates than wild fish, indicating a differential vulnerability within aquatic biota. This study lays a foundational basis for the risk assessment of OPEs as emerging contaminants and underscores the imperative to prioritize the examination of bioaccumulation effects, particularly in benthic invertebrates, to inform future environmental safeguarding strategies.

Fugacity- and biotransformation-based mechanistic insights into the trophic transfer of organophosphate flame retardants in a subtropical coastal food web from the Northern Beibu Gulf of China

The bioaccumulation and trophic transfer of organophosphate flame retardants (OPFRs) in marine ecosystems have attracted great attention in recent research, but our understanding of the trophic transfer mechanisms involved is limited. In this study, we investigated the trophodynamics of OPFRs and their metabolites in a subtropical coastal food web collected from the northern Beibu Gulf, China, and characterized their trophodynamics using fugacity- and biotransformation-based approaches. Eleven OPFRs and all seven metabolites were simultaneously quantified in the shellfish, crustacean, pelagic fish, and benthic fish samples, with total concentrations ranging from 164 to 4.11 × 104 and 4.56-4.28 × 103 ng/g lipid weight, respectively. Significant biomagnification was observed only for tris (phenyl) phosphate (TPHP) and tris (2-ethylhexyl) phosphate (TEHP), while other compounds except for tris(2-chloroethyl) phosphate (TCEP) displayed biomagnification trends based on Monte Carlo simulations. Using a fugacity-based approach to normalize the accumulation of OPFRs in biota to their relative biological phase composition, storage lipid is the predominant biological phase for the mass distribution of 2-ethylhexyl diphenyl phosphate (EHDPHP) and TPHP. The water content and structure protein are equally important for TCEP, whereas lipid and structure protein are the two most important phases for other OPFRs. The mass distribution of these OPFRs along with TLs can explain their trophodynamics in the food web. The organophosphate diesters (as OPFR metabolites) also displayed biomagnification trends based on bootstrapped estimation. The correlation analysis and Korganism-water results jointly suggested the metabolites accumulation in high-TL organisms was related to biotransformation processes. The metabolite-backtracked trophic magnification factors for tri-n‑butyl phosphate (TNBP) and TPHP were both greater than the values that accounted for only the parent compounds. This study highlights the incorporation of fugacity and biotransformation analysis to characterize the trophodynamic processes of OPFRs and other emerging pollutants in food webs.

Distribution and trophodynamics of substituted diphenylamine antioxidants and benzotriazole UV stabilizers in a freshwater ecosystem and the adjacent riparian environment

Substituted diphenylamine antioxidants (SDPAs) and benzotriazole UV stabilizers (BZT-UVs) are industrial additives of emerging environmental concern. However, little is known about their environmental fate and bioaccumulation. This study investigated the concentrations of SDPAs and BZT-UVs in the water, sediment and biota samples in the freshwater ecosystem and adjacent riparian environment using Hamilton Harbour in the Great Lakes of North America as a study site. The bioaccumulation factors and trophodynamics of these contaminants were studied using field-collected samples. Eight target SDPAs and two BZT-UVs (2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (UV234) and 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV328)) were frequently detected in the sediment, water and biota samples. UV328 showed significantly greater concentrations in water (0.28-2.8 ng L-1) and sediment (8.3-48 ng g-1, dry weight) than other target contaminants, implying greater contamination of UV328 in Hamilton Harbour. SDPAs exhibited trophic dilution in species living in the water, whereas UV234 was biomagnified in the same samples. No clear trophodynamic trend was found for UV328 for water-respiring species. Air-breathing invertebrates had higher concentrations of both SDPAs and BZT-UVs than water-respiring invertebrates, and biomagnification was observed particularly for adult dragonflies. These results suggest that the trophodynamics of SDPAs and BZT-UVs vary depending on whether the food web is terrestrial or aquatic. Future research should investigate the occurrence and partitioning of SDPAs and BZT-UVs in the air-water interface and evaluate the toxicities of these contaminants in air-breathing species.

Biomagnification of persistent organic pollutants (POPs) in detritivorous, phytophagous, and predatory invertebrates: How POPs enter terrestrial food web?

Invertebrates are primary contributors to fluxes of nutrients, energy, and contaminants in terrestrial food webs, but the trophodynamic of contaminants in invertebrate food chains is not fully understood. In this study, occurrence and biomagnification of persistent organic pollutants (POPs) were assessed in detritivorous, phytophagous, and predatory invertebrate food chains. Detritivorous species (earthworm and dung beetle) have higher concentrations of POPs than other species. Different composition patterns and biomagnification factors (BMFs) of POPs were observed for invertebrate species. Negative correlations were found between BMFs and log KOW of POPs for detritivorous and most phytophagous species. In contrast, parabolic relationships between BMFs and log KOW were observed in snails and predatory species, possibly attributed to the efficient digestion and absorption of diet and POPs for them. Bioenergetic characteristics are indicative of the biomagnification potential of POPs in terrestrial wildlife, as suggested by the significant and positive correlation between basal metabolic rates (BMRs) and BMFs of BDE 153 for invertebrates, amphibians, reptiles, birds, and mammals. The estimations of dietary exposure suggest that the terrestrial predators, especially feeding on the underground invertebrates, could be exposed to high level POPs from invertebrates.

Occurrence, bioaccumulation and trophodynamics of organophosphate esters in the marine biota web of Laizhou Bay, Bohai Sea

The trophodynamic of organophosphate esters (OPEs) has not been known well despite their widespread occurrence in the aquatic environments. In this study, ten species of crustacean, seven species of mollusk, and 22 species of fish were collected in the Laizhou Bay (LZB) to examine the occurrence, bioaccumulation, and trophic transfer, and health risk of eight traditional OPEs and three emerging oligomeric OPEs. The results showed that total concentration of OPEs was 2.04 to 28.6 ng g-1 ww in the muscle of crustacean, mollusk, and fish and 2.62 to 60.6 ng g-1 ww in the fish gill. Chlorinated OPEs averagely contributed to over 85% of total OPEs while oligomeric OPEs averagely accounted for approximate 4%. The average log apparent bioaccumulation factor (ABAF) ranged from - 0.4 L kg-1 ww for triethyl phosphate to 2.4 L kg-1 ww for resorcinol-bis (diphenyl) phosphate. Apparent trophic magnification factors (ATMF) of individual OPE were generally less than 1, demonstrating the biodilution effect of the OPEs in the organism web of LZB. Additionally, the log ABAF and ATMF of OPEs were significantly positively correlated to their log Kow but negatively correlated to their biotransformation rate constant (BRC). Therefore, the OPEs with high Kow and low BRC tend to more accumulate in the marine organisms. The health risks associated with OPEs through the consumption of the seafood from the bay were low, even at high exposure scenario.

Bioaccumulation and Trophodynamics of Novel Brominated Flame Retardants (NBFRs) in Marine Food Webs from the Arctic and Antarctic Regions

The pervasive contamination of novel brominated flame retardants (NBFRs) in remote polar ecosystems has attracted great attention in recent research. However, understanding regarding the trophic transfer behavior of NBFRs in the Arctic and Antarctic marine food webs is limited. In this study, we examined the occurrence and trophodynamics of NBFRs in polar benthic marine sediment and food webs collected from areas around the Chinese Arctic Yellow River Station (n = 57) and Antarctic Great Wall Station (n = 94). ∑7NBFR concentrations were in the range of 1.27-7.47 ng/g lipid weight (lw) and 0.09-1.56 ng/g lw in the Arctic and Antarctic marine biota, respectively, among which decabromodiphenyl ethane (DBDPE) was the predominant compound in all sample types. The biota-sediment bioaccumulation factors (g total organic carbon/g lipid) of NBFRs in the Arctic (0.85-3.40) were 4-fold higher than those in the Antarctica (0.13-0.61). Trophic magnification factors (TMFs) and their 95% confidence interval (95% CI) of individual NBFRs ranged from 0.43 (95% CI: 0.32, 0.60) to 1.32 (0.92, 1.89) and from 0.34 (0.24, 0.49) to 0.92 (0.56, 1.51) in the Arctic and Antarctic marine food webs, respectively. The TMFs of most congeners were significantly lower than 1, indicating a trophic dilution potential. This is one of the very few investigations on the trophic transfer of NBFRs in remote Arctic and Antarctic marine ecosystems, which provides a basis for exploring the ecological risks of NBFRs in polar regions.

First Evidence of the Bioaccumulation and Trophic Transfer of Tire Additives and Their Transformation Products in an Estuarine Food Web

The discovery of the significant lethal impacts of the tire additive transformation product N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6PPD-Q) on coho salmon has garnered global attention. However, the bioaccumulation and trophic transfer of tire additives and their transformation products (TATPs) within food webs remain obscure. This study first characterized the levels and compositions of 15 TATPs in the Pearl River Estuary, estimated their bioaccumulation and trophic transfer potential in 21 estuarine species, and identified priority contaminants. Our observations indicated that TATPs were prevalent in the estuarine environment. Eight, six, seven, and 10 TATPs were first quantified in the shrimp, sea cucumber, snail, and fish samples, with total mean levels of 45, 56, 64, and 67 ng/g (wet weight), respectively. N,N'-Diphenyl-p-phenylenediamine (DPPD) and N,N'-bis(2-methylphenyl)-1,4-benzenediamine (DTPD) exhibited high bioaccumulation. Significant biodilution was only identified for benzothiazole, while DPPD and DTPD displayed biomagnification trends based on Monte Carlo simulations. The mechanisms of bioaccumulation and trophodynamics of TATPs could be explained by their chemical hydrophobicity, molecular mass, and metabolic rates. Based on a multicriteria scoring technique, DPPD, DTPD, and 6PPD-Q were characterized as priority contaminants. This work emphasizes the importance of biomonitoring, particularly for specific hydrophobic tire additives.

Global environmental and toxicological impacts of polybrominated diphenyl ethers versus organophosphate esters: A comparative analysis and regrettable substitution dilemma

The prevalence of organophosphate esters (OPEs) in the global environment is increasing, which aligns with the decline in the usage of polybrominated diphenyl ethers (PBDEs). PBDEs, a category of flame retardants, were banned and classified as persistent organic pollutants (POPs) through the Stockholm Convention due to their toxic and persistent properties. Despite a lack of comprehensive understanding of their ecological and health consequences, OPEs were adopted as replacements for PBDEs. This research aims to offer a comparative assessment of PBDEs and OPEs in various domains, specifically focusing on their persistence, bioaccumulation, and toxicity (PBT) properties. This study explored physicochemical properties (such as molecular weight, octanol-water partition coefficient, octanol-air partition coefficient, Henry's law constant, and vapor pressures), environmental behaviors, global concentrations in environmental matrices (air, water, and soil), toxicities, bioaccumulation, and trophic transfer mechanisms of both groups of compounds. Based on the comparison and analysis of environmental and toxicological data, we evaluate whether OPEs represent another instance of regrettable substitution and global contamination as much as PBDEs. Our findings indicate that the physical and chemical characteristics, environmental behaviors, and global concentrations of PBDEs and OPEs, are similar and overlap in many instances. Notably, OPE concentrations have even surged by orders of several magnitude compared to PBDEs in certain pristine regions like the Arctic and Antarctic, implying long-range transport. In many instances, air and water concentrations of OPEs have been increased than PBDEs. While the bioaccumulation factors (BAFs) of PBDEs (ranging from 4.8 to 7.5) are slightly elevated compared to OPEs (-0.5 to 5.36) in aquatic environments, both groups of compounds exhibit BAF values beyond the threshold of 5000 L/kg (log10 BAF > 3.7). Similarly, the trophic magnification factors (TMFs) for PBDEs (ranging from 0.39 to 4.44) slightly surpass those for OPEs (ranging from 1.06 to 3.5) in all cases. Metabolic biotransformation rates (LogKM) and hydrophobicity are potentially major factors deciding their trophic magnification potential. However, many compounds of PBDEs and OPEs show TMF values higher than 1, indicating biomagnification potential. Collectively, all data suggest that PBDEs and OPEs have the potential to bioaccumulate and transfer through the food chain. OPEs and PBDEs present a myriad of toxicity endpoints, with notable overlaps encompassing reproductive issues, oxidative stress, developmental defects, liver dysfunction, DNA damage, neurological toxicity, reproductive anomalies, carcinogenic effects, and behavior changes. Based on our investigation and comparative analysis, we conclude that substituting PBDEs with OPEs is regrettable based on PBT properties, underscoring the urgency for policy reforms and effective management strategies. Addressing this predicament before an exacerbation of global contamination is imperative.

Modelling microplastic bioaccumulation and biomagnification potential in the Galápagos penguin ecosystem using Ecopath and Ecosim (EwE) with Ecotracer

Bioaccumulation and biomagnification of anthropogenic particles are crucial factors in assessing microplastic impacts to marine ecosystems. Microplastic pollution poses a significant threat to iconic and often endangered species but examining their tissues and gut contents for contaminant analysis via lethal sampling is challenging due to ethical concerns and animal care restrictions. Incorporating empirical data from prey items and fecal matter into models can help trace microplastic movement through food webs. In this study, the Galápagos penguin food web served as an indicator species to assess microplastic bioaccumulation and biomagnification potential using trophodynamic Ecopath with Ecosim (EwE) modelling with Ecotracer. Empirical data collected from surface seawater near Galápagos penguin colonies, zooplankton, penguin prey, and penguin scat in October 2021 were used to inform the ecosystem model. Multiple scenarios, including a 99% elimination rate, were employed to assess model sensitivity. Model predictions revealed that microplastics can bioaccumulate in all predator-prey relationships, but biomagnification is highly dependent on the elimination rate. It establishes the need for more research into elimination rates of different plastics, which is a critical missing gap in current microplastic ecotoxicological and bioaccumulation science. Compared to empirical data, modelling efforts underpredicted microplastic concentrations in zooplankton and over-predicted concentrations in fish. Ultimately, the ecosystem modelling provides novel insights into potential microplastics' bioaccumulation and biomagnification risks. These findings can support regional marine plastic pollution management efforts to conserve native and endemic species of the Galápagos Islands and the Galápagos Marine Reserve.

The biological invasion of an apex predator (Silurus glanis) amplifies PCB transfer in a large lake food web

Invasive species can affect food web structure possibly modifying the transfer of pollutants in ecosystems but this facet of biological invasion remains largely unexplored. We examined how trophic and ontogenetic characteristics of the invasive European catfish could differ from its native counterpart, the Northern pike, possibly resulting in the amplification of PCB transfer to the higher trophic levels in a large lake food web. The PCB contents of catfish and pike were on average low (Ʃ7 PCBi 42.4 ± 38.6 ng g-1 ww and 37.9 ± 49.4 ng g-1 ww respectively) and dominated by PCB153 (~35 % of the PCB contamination). Only the largest pike (126 cm) slightly exceeded the European sanitary threshold of 125 ng g-1 ww Ʃ6 PCBi-NDL. Both species increased in trophic position with body size while catfish had clearly higher littoral reliance than pike indicating they exploited complementary trophic niches. PCB biomagnification was identified only for catfish (PCB153, Ʃ7 PCBi) leading to trophic magnification factor of ~5. PCB ontogenetic bioaccumulation was pervasive for catfish (PCB101, PCB118, PCB153, PCB138 and Ʃ7 PCBi) and identified for pike only regarding PCB101. The derived size accumulation factors (~1.02) indicated a size-doubling PCB contamination of ~40 cm for catfish. This finding suggested that catfish would exceed the European sanitary threshold at body size larger than 168 cm possibly constraining their commercial exploitation. Our results highlighted that the invasive catfish was a littoral-oriented apex predator occupying an alternative trophic niche as compared to pike thereby modifying the lake food web structure that resulted in an enhancement of PCB transfer to higher trophic levels. The biomagnification and ontogenetic bioaccumulation of catfish underlined the impact of this biological invasion on the fate of PCB in the ecosystem. Finally, the remarkable inter-individual PCB contamination suggested variable inter-individual PCB exposure likely associated to localized hotspots of PCB contamination in the lake.

Formation of Targeted and Novel Disinfection Byproducts during Chlorine Photolysis in the Presence of Bromide

Chlorine photolysis is an advanced oxidation process that relies on the combination of direct chlorination by free available chlorine, direct photolysis, and reactive oxidants to transform contaminants. In waters that contain bromide, free available bromine and reactive bromine species can also form. However, little is known about the underlying mechanisms or formation potential of disinfection byproducts (DBPs) under these conditions. We investigated reactive oxidant generation and DBP formation under dark conditions, chlorine photolysis, and radical-quenched chorine photolysis with variable chlorine (0-10 mg-Cl2/L) and bromide (0-2,000 μg/L) concentrations, as well as with free available bromine. Probe loss rates and ozone concentrations increase with chlorine concentration and are minimally impacted by bromide. Radical-mediated processes partially contribute to the formation targeted DBPs (i.e., trihalomethanes, haloacetic acids, haloacetonitriles, chlorate, and bromate), which increase with increasing chlorine concentration. Chlorinated novel DBPs detected by high-resolution mass spectrometry are attributable to a combination of dark chlorination, direct halogenation by reactive chlorine species, and transformation of precursors, whereas novel brominated DBPs are primarily attributable to dark bromination of electron-rich formulas. The formation of targeted and novel DBPs during chlorine photolysis in waters with elevated bromide may limit treatment applications.

Trophodynamics of halogenated organic pollutants (HOPs) in aquatic food webs

Halogenated organic pollutants (HOPs) represent hazardous and persistent compounds characterized by their capacity to accumulate within organisms and endure in the environment. These substances are frequently transmitted through aquatic food webs, engendering potential hazards to ecosystems and human well-being. The trophodynamics of HOPs in aquatic food webs has garnered worldwide attention within the scientific community. Despite comprehensive research endeavors, the prevailing trajectory of HOPs, whether inclined toward biomagnification or biodilution within global aquatic food webs, remains unresolved. Furthermore, while numerous studies have probed the variables influencing the trophic magnification factor (TMF), the paramount determinant remains elusive. Collating a compendium of pertinent literature encompassing TMFs from the Web of Science between 1994 and 2023, our analysis underscores the disparities in attention accorded to legacy HOPs compared to emerging counterparts. A discernible pattern of biomagnification characterizes the behavior of HOPs within aquatic food webs. Geographically, the northern hemisphere, including Asia, Europe, and North America, has demonstrated greater biomagnification than its southern hemisphere counterparts. Utilizing a boosted regression tree (BRT) approach, we reveal that the food web length and type emerge as pivotal determinants influencing TMFs. This review provides a valuable basis for gauging ecological and health risks, thereby facilitating the formulation of robust standards for managing aquatic environments.

Occurrence and Trophic Transfer of Polychlorinated Naphthalenes (PCNs) in the Arctic and Antarctic Benthic Marine Food Webs

Information about the occurrence and trophic transfer of polychlorinated naphthalenes (PCNs) in polar ecosystems is vital but scarce. In this study, PCNs were analyzed in benthic marine sediment and several biological species, collected around the Chinese polar scientific research stations in Svalbard in the Arctic and South Shetland Island in Antarctica. Total PCNs in biota ranged from 28 to 249 pg/g of lipid weight (lw) and from 11 to 284 pg/g lw in the Arctic and Antarctic regions, respectively. The concentrations and toxic equivalent (TEQ) of PCNs in polar marine matrices remained relatively low, and the compositions were dominated by lower chlorinated homologues (mono- to trichlorinated naphthalenes). Trophic magnification factors (TMFs) were calculated for congeners, homologues, and total PCNs in the polar benthic marine food webs. Opposite PCN transfer patterns were observed in the Arctic and Antarctic regions, i.e., trophic dilution and trophic magnification, respectively. This is the first comprehensive study of PCN trophic transfer behaviors in remote Arctic and Antarctic marine regions, providing support for further investigations of the biological trophodynamics and ecological risks of PCNs.

Phytoplankton Biological Pump Controls the Spatiotemporal Bioaccumulation and Trophic Transfer of Antibiotics in a Large Subtropical River

The spatiotemporal bioaccumulation, trophic transfer of antibiotics, and regulation of the phytoplankton biological pump were quantitatively evaluated in the Pearl River, South China. The occurrence of antibiotics in organisms indicated a significant spatiotemporal trend associated with the life cycle of phytoplankton. Higher temporal bioaccumulation factors (BAFs) were found in phytoplankton at the bloom site, while lower BAFs of antibiotics in organisms could not be explained by phytoplankton biomass dilution but were attributed to the low bioavailability of antibiotics, which was highly associated with distribution coefficients (R2 = 0.480-0.595, p < 0.05). Such lower BAFs of antibiotics in phytoplankton at higher biomass sites hampered the entry of antibiotics into food webs, and trophic dilutions were subsequently observed for antibiotics except for ciprofloxacin (CFX) and sulfamerazine (SMZ) at sites with blooms in all seasons. Distribution of CFX, norfloxacin (NFX), and sulfapyridine (SPD) showed further significant positive relationships with the plasma protein fraction (R2 = 0.275-0.216, p < 0.05). Both mean BAFs and trophic magnification factors (TMFs) were significantly negatively correlated with phytoplankton biomass (R2 = 0.661-0.741, p < 0.05). This study highlights the importance of the biological pump in the regulation of spatiotemporal variations in bioaccumulation and trophic transfer of antibiotics in anthropogenic-impacted eutrophic rivers in subtropical regions.

Metal-specific biomagnification and trophic dilution in the coastal foodweb of the California sea lion (Zalophus californianus) off Bahía Magdalena, Mexico: The role of the benthic-pelagic foodweb in the trophic transfer of trace and toxic metals

Trace metals concentrations along with stable isotopes ratios were measured in marine algae, sea grass, sponges, echinoderms, mollusks, crustaceans, fishes, and the California sea lion, to assess the bioaccumulation potential and detect potential risks for top predators off Bahia Magdalena, Mexico. We assessed the trophic magnification factor (TMF) to determine the potential for biomagnification of 11 trace metals. The concentrations of Fe and Zn were one order of magnitude higher than all other metals. Concentrations of As, Cu, Cd, Co, Cr, Fe, Mn and Ni correlated negatively with trophic level, supporting trophic dilution (TMF < 1, p > 0.05), while Zn and Hg had significant trophic magnification (TMF > 1, p < 0.05) when assessing only the benthic-pelagic foodweb. This research provides a baseline concentration of metals in multiple species, metal-specific foodweb bioaccumulation and biomagnification of mercury, underscoring the key role of the macrobenthic community as biovectors for trophic transfer of Hg through the foodweb to the California sea lion.

Legacy and novel brominated flame retardants in a lab-constructed freshwater ecosystem: Distribution, bioaccumulation, and trophic transfer

The extensive utilization of both legacy and novel brominated flame retardants (BFRs) leads to high environmental concentrations, which would be bioaccumulated by organisms and further transferred through the food webs, causing potential risks to humans. In this study, five BFRs, that showed high detection frequencies and concentrations in sediments from an e-waste dismantling site in Southern China, namely 2,3,4,5,6-pentabromotoluene (PBT), hexabromobenzene (HBB), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), decabromodiphenyl ethane (DBDPE), and decabromodiphenyl ether (BDE209), were selected as target pollutants in the lab-constructed aquatic food web as part of a micro-ecosystem, to investigate their distribution, bioaccumulation, and trophic transfer patterns. The significant correlations between different samples in the food web indicated that the dietary uptake appeared to influence the levels of BFRs in organisms. Significant negative correlations were observed between the trophic level of organisms and the lipid-normalized concentrations of BTBPE and DBDPE, indicating the occurrence of trophic dilution after 5-month exposure. However, the average values of bioaccumulation factors (BAFs) were from 2.49 to 5.17 L/kg, underscoring the importance of continued concern for environmental risks of BFRs. The organisms occupying higher trophic levels with greater bioaccumulation capacities may play a pivotal role in determining the trophic magnification potentials of BFRs. This research provides a helpful reference for studying the impacts of feeding habits on bioaccumulation and biomagnification, as well as for identifying the fate of BFRs in aquatic environment.

Role of Gastrointestinal Microbiota from Crucian Carp in Microbial Transformation and Estrogenicity Modification of Novel Plastic Additives

Ingestion is a major exposure route for hydrophobic organic pollutants in fish, but the microbial transformation and estrogenic modification of the novel plastic additives by the gut microbiota of fish remain obscure. Using an in vitro approach, we provide evidence that structure-related transformation of various plastic additives by the gastric and intestinal (GI) microbiota from crucian carp, with the degradation ratio of bisphenols and triphenyl phosphate faster than those of brominated compounds. The degradation kinetics for these pollutants could be limited by oxygen and cometabolic substrates (i.e., glucose). The fish GI microbiota could utilize the vast majority of carbon sources in a Biolog EcoPlate, suggesting their high metabolic potential and ability to transform various organic compounds. Unique microorganisms associated with transformation of the plastic additives including genera of Citrobacter, Klebsiella, and some unclassified genera in Enterobacteriaceae were identified by combining high-throughput genetic analyses and metagenomic analyses. Through identification of anaerobic transformation products by high-resolution mass spectrometry, alkyl-cleavage was found the common transformation mechanism, and hydrolysis was the major pathway for ester-containing pollutants. After anaerobic incubation, the estrogenic activities of triphenyl phosphate and bisphenols A, F, and AF declined, whereas that of bisphenol AP increased.

Organophosphate esters (OPEs) in the marine environment: Spatial distribution and profiles in French coastal bivalves

Organophosphate esters (OPEs), chemicals widely used in industrial production, electronics and domestic products, have become ubiquitous environmental contaminants. In this study, the levels and spatial distribution of 11 OPEs (aryl, alkyl and halogenated) were investigated in over 100 samples of filter-feeding bivalves collected yearly between 2014 and 2021 at sites of contrasted pressure along the French coasts. OPEs were found in virtually all samples, indicating their widespread spatial and temporal occurrence in coastal bivalves and the relevance of their biomonitoring. The median concentrations were between 0.4 (TMPP) and 4.9 ng g-1 dry weight (TCIPP), with TCIPP, TNBP and EHDPP found at the highest median values. TCEP and TBOEP were not frequently detected overall, but each year, the same sites showed repeatedly high concentrations. Structurally-related OPEs generally correlated, but the geographical distributions were not predictable from known anthropogenic pressures (population in the catchment area, industry), with little comparability with other hydrophobic contaminants. If the relation between sources of OPEs and bioaccumulated levels remains uncertain, local hotspots, rather than riverine/atmospheric transportation, could account for their geographical distribution. A systematic review of the levels of OPEs found in filter-feeding bivalves worldwide revealed comparable levels in our study with those reported elsewhere; however, the levels across and within (when available) studies generally spanned several orders of magnitude, indicating high spatial and temporal heterogeneity. In view of the growing concerns regarding OPEs, this study provides essential reference data for future studies of their occurrence on European coasts and supports the need for a more systematic (bio)monitoring of this class of contaminant.

Aquatic-terrestrial transfer of neonicotinoid insecticides in riparian food webs

Current-use pesticides are ubiquitous in freshwaters globally, often at very low concentrations. Emerging aquatic insects can accumulate pesticides during their aquatic development, which can be retained through their metamorphosis into terrestrial adults. Emerging insects thus provide a potential, yet largely understudied linkage for exposure of terrestrial insectivores to waterborne pesticides. We measured 82 low to moderately lipophilic organic pesticides (logK_ow: -2.87 to 6.9) in the aquatic environment, emerging insects and web-building riparian spiders from stream sites impacted by agricultural land use. Insecticides, mainly neuro-active neonicotinoids were ubiquitous and had the highest concentrations in emerging insects and spiders (∑ insecticides: 0.1-33 and 1-240 ng/g, respectively), although their concentrations in water were low, even when compared to global levels. Furthermore, neonicotinoids, although not considered to be bioaccumulative, were biomagnified in riparian spiders. In contrast, concentrations of fungicides and most herbicides decreased from the aquatic environment to the spiders. Our results provide evidence for the transfer and accumulation of neonicotinoids across the aquatic-terrestrial ecosystem boundary. This could threaten food webs in ecologically sensitive riparian areas worldwide.

Trophodynamic of endocrine disrupting compounds in the aquatic food webs: Association with hydrophobicity and biota metabolic rate

Increasing concentration of endocrine disrupting compounds (EDCs) are released into the aquatic environment, resulting in irreversible effects on the endocrine and reproductive systems of biota. How the liver enzymes affect metabolic rate of these compounds and thus their structure-related trophic transfer in aquatic food webs remains largely unknown. In this study, the concentrations of seven common EDCs were measured in 15 species of fish, 7 invertebrate species and plankton collected from Liuxi River to Pearl River, South China. The mean ΣEDC concentrations generally were found to increase as follows: plankton (29.59 ng g^-1 dw) < invertebrate species (50.69 ng g^-1 dw) < fish (122.56 ng g^-1 dw), with 4-nonylphenol (4-NP) and bisphenol S (BPS) as the predominant components. Trophic magnification factors (TMFs) values were >1.0 ranged from 1.30 (BPS) to 4.07 (4-NP), indicating trophic magnification potential. Measurement of metabolism and activities of microsomal CYP450 enzymes were performed in the fish liver microsomes of Hypophthalmichthys molitrix ([TL] = 2.27), Cirrhinus mrigala (TL = 3.87) and Odontamblyopus rubicundus (TL = 4.73). TMFs were significantly negatively correlated with the obtained in vitro biotransformation clearance rates (CL _{in vitro}) of EDCs and CYP450 enzymes activities. A multiple linear regression model indicated that biotransformation clearance is a more powerful predictor for TMFs than the hydrophobicity (Kow) to drive changes in the studied aquatic food web trophodynamics.

Bioaccumulation and Trophic Transfer of Organophosphate Flame Retardants and Their Metabolites in the Estuarine Food Web of the Pearl River, China

The accumulation and trophodynamics of organophosphate flame retardants (OPFRs) and their metabolites were investigated in the estuarine food web of the Pearl River, China. The mean ∑OPFR concentration among the investigated species increased in the following order: fish [431 ± 346 ng/g lipid weight (lw)] < snail (1310 ± 621 ng/g lw) < shrimp (1581 ± 1134 ng/g lw) < crab (1744 ± 1397 ng/g lw). The di-alkyl phosphates (DAPs) of di-(n-butyl) phosphate (DNBP), bis(2-butoxyethyl) phosphate (BBOEP), and diphenyl phosphate (DPHP) were the most abundant metabolites, with concentrations same as or even higher than their corresponding parent compounds. The log bioaccumulation factors for most OPFRs were lower than 3.70, and significant biomagnification was only found for trisphenyl phosphate [TPHP, with the trophic magnification factors (TMFs) > 1]. The TMFs of OPFRs, except for TPHP and tributyl phosphate had a positive correlation with lipophilicity (log K_OW, p ≤ 0.05) and a negative correlation with the biotransformation rate (log K_M, p ≤ 0.05). The mean TMF > 1 was observed for all of the OPFR metabolites based on the bootstrap regression method. The "pseudo-biomagnification" of OPFR metabolites might be attributed to the biotransformation of OPFRs in organisms at high trophic levels.

Improving the qualities of the trophic magnification factors (TMFs): A case study based on scaled Δ15N trophic position framework and separate baseline species

Scientific understanding of trophic magnification factors (TMFs) is conducive to formulating environmental management measures. Trophic position (TP) of species is the key parameter in TMFs assessment. Nitrogen stable isotopes (δ¹⁵N) provide a powerful tool to estimate TP. However, some limitations could introduce considerable uncertainty into TP and TMFs assessment which mainly includes: 1) determination of Δ¹⁵N between two adjacent trophic positions; 2) determination of baseline species. Different from the widely used constant Δ¹⁵N (3.4 ‰) between two adjacent trophic positions, which is called additive Δ¹⁵N framework, Δ¹⁵N gradually decreases as trophic position increases under scaled Δ¹⁵N framework, which has been confirmed by more and more laboratory studies and meta-analyses. In this study, we sampled in two similar littoral ecosystems separated by one natural dam, which is called Small Xingkai Lake and Xingkai Lake, analyzed the δ¹⁵N and total mercury (THg) of each species. On the one hand, we compared the TP of species under the additive Δ¹⁵N framework and scaled Δ¹⁵N framework with the White shrimp (Exopalaemon modestus) as baseline species in two lakes respectively. On the other hand, we explored the possible changes in TMFs based on TP. Our results show, under the scaled Δ¹⁵N framework, the trophic position of the same species is higher, while TMFs is lower compared with the additive Δ¹⁵N framework; even if in the two interconnected lakes, distributed the same baseline species, in the similar ecosystem, separate baselines should also be used. In this study, two frameworks of the food chain were compared in two interconnected freshwater ecosystems for the first time. The difference between TMFs of two lakes was obvious under scaled framework but not under additive framework. We also recommend that future TMFs assessments should be based on the scaled Δ¹⁵N framework because it has improved the accuracy of trophic position assessment.

Riparian Spiders: Sentinels of Polychlorinated Dibenzo-p-dioxin and Dibenzofuran-Contaminated Sediment

Polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran (PCDD/F) are persistent, toxic, and bioaccumulative. Currently, PCDD/F monitoring programs primarily use fish and birds with potentially large home ranges to monitor temporal trends over broad spatial scales; sentinel organisms that provide targeted sediment contaminant information across small geographic areas have yet to be developed. Riparian orb-weaving spiders, which typically have small home ranges and consume primarily adult aquatic insects, are potential PCDD/F sentinels. Recent studies have demonstrated that spider tissue concentrations indicate the source and magnitude of dioxin-like chlorinated compounds in contaminated sediments, including polychlorinated biphenyls (PCBs). Our aim in the present study was to assess the utility of riparian spiders as sentinels for PCDD/F-contaminated sediments. We measured PCDD/F (total [Σ] and homologs) in surface sediments and spiders collected from three sites within the St. Louis River basin (Minnesota and Wisconsin, USA). We then compared (1) patterns in ΣPCDD/F concentrations between sediment and spiders, (2) the distribution of homologs within sediments and spiders when pooled across sites, and (3) the relationship between sediment and spider concentrations of PCDD/F homologs across 13 stations sampled across the three sites. The ΣPCDD/F concentrations in sediment (mean ± standard error 286 591 ± 97 614 pg/g) were significantly higher than those in riparian spiders (2463 ± 977 pg/g, p < 0.001), but the relative abundance of homologs in sediment and spiders were not significantly different. Spider homolog concentrations were significantly and positively correlated with sediment concentrations across a gradient of sediment PCDD/F contamination (R²  = 0.47, p < 0.001). Our results indicate that, as has been shown for other legacy organic chemicals like PCBs, riparian spiders are suitable sentinels of PCDD/F in contaminated sediment. Environ Toxicol Chem 2023;42:414-420. © 2022 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Organophosphate esters (OPEs) in a coral reef food web of the Xisha Islands, South China Sea: Occurrence, trophodynamic, and exposure risk

Despite organophosphate esters (OPEs) are widely prevalent in the environment, however, limited information is available regarding their occurrence, trophodynamics, and exposure risks in coral reef ecosystems. In this study, 11 OPEs were investigated in a tropical marine food web (7 fish species and 9 benthos species) from the Xisha (XS) Islands, South China Sea (SCS). The ∑₁₁OPEs were 1.52 ± 0.33 ng/L, 2227 ± 2062 ng/g lipid weight (lw), 1024 ± 606 ng/g lw, and 1800 ± 1344 ng/g lw in seawater, fish, molluscs, and corals, respectively. Tris (2-chloroisopropyl) phosphate (TCIPPs) were the dominant OPEs in seawater, fish, and molluscs, while tris (2-butoxyethyl) phosphate (TBOEP) predominated in coral tissues. Abiotic and biotic factors jointly affect the OPEs enrichment in marine organisms. Trophic magnification factors (TMFs) (range: 1.31-39.2) indicated the biomagnification potency of OPEs. A dietary exposure risk assessment indicated that OPEs at current levels in coral reef fish posed a low risk to human health but were not negligible. Overall, this study contributes to a further understanding of the environmental behaviors of OPEs in coral reef ecosystems.

Seasonal and plurennial changes of POPs repository in freshwater zooplankton: A 10-year study in the large deep subalpine Lake Maggiore (Italy)

Determining the concentration of POPs (Persistent Organic Pollutants) such as total dichlorodiphenyltrichloroethane (DDT_tot) and polychlorinated biphenyls (PCBs) in the zooplankton is essential for evaluating the level of toxicity in the environment and the risk to ecosystem health. The extent to which POPs persist in the environment and affect human health depends on accumulation in the different components of the zooplankton community such as particle feeders and/or predators and their subsequent consumption by fish, which varies seasonally. We analyzed ten-years (2011-2020) of seasonal data on POPs in the crustacean zooplankton community of Lake Maggiore (Italy). The concentration of total DDTs, as sum of all congeners ranged between 23.5 and 156.9 ng/g dry weight, while sumPCB₁₄ ranged from 24.4 and 133.6 ng/g dry weight. We traced particle feeders' vs predatory taxa within the zooplankton community using carbon and nitrogen stable isotopic values. POPs concentration was significantly related to the nitrogen isotopic values. The zooplankton biomass increase in Spring was important, both through this being a period of increased metabolism and activity of planktivorous fish and also as it was the period when the zooplankton repository of POPs was at a maximum. DDT_tot stocked in zooplankton ≥450 μm was up to 275 ng/m², while sumPCB₁₄ was 285 ng/m² in 2013. A decrease of DDT_tot stocked in the zooplankton repository characterized the last five years examined, when mean annual values (14.8-56.9 ng/m²) were less than half those of the previous period (50.7-128.6 ng/m²).

Distinct biomagnification of chlorinated persistent organic pollutants in adjacent aquatic and terrestrial food webs

Biomagnification of persistent organic pollutants (POPs) in food webs has been studied for many years. However, the different processes and influencing factors in biomagnification of POPs in aquatic and terrestrial food webs still need clarification. Polychlorinated biphenyls (PCBs) and short-chain chlorinated paraffins (SCCPs) were measured in organisms from adjacent terrestrial and aquatic environment in this study. The median levels of PCBs in terrestrial and aquatic organisms were 21.7-138 ng/g lw and 37.1-149 ng/g lw, respectively. SCCP concentrations were 18.6-87.3 μg/g lw and 21.4-93.9 μg/g lw in terrestrial and aquatic organisms, respectively. Biomagnification factors (BMFs) of PCBs increased with higher log K_OW in all food chains. BMFs of SCCPs were negatively correlated with log K_OW in aquatic food chains, but positively correlated with log K_OW in terrestrial food chains. The terrestrial food web had similar trophic magnification factors (TMFs) of PCBs, and higher TMFs of SCCPs than the aquatic food web. Biomagnification of PCBs was consistent in aquatic and terrestrial food webs, while SCCPs had higher biomagnification potential in terrestrial than aquatic organisms. The distinct biomagnification of SCCPs was affected by the respiratory elimination for terrestrial organisms, the different metabolism rates in various species, and more homotherms in terrestrial food webs. Fugacity model can well predict levels of less hydrophobic chemicals, and warrants more precise toxicokinetic data of SCCPs.

Trace elements, dioxins and PCBs in different fish species and marine regions: Importance of the taxon and regional features

Chemical contaminant concentrations in wild organisms are used to assess environmental status under the European Marine Strategy Framework Directive. However, this approach is challenged by the complex intra- and inter-species variability, and the different regional features. In this study, concentrations in trace elements (As, Cd, Hg and Pb), polychlorinated biphenyls (PCBs), polychlorodibenzo-para-dioxines (PCDDs) and polychlorodibenzofuranes (PCDFs) were monitored in 8 fish species sampled on the continental shelf of three French regions: the Eastern English Channel (EEC) and Bay of Biscay (BoB) in the Northeast Atlantic Ocean, and the Gulf of Lions (GoL) in Western Mediterranean Sea. Our objectives were to identify species or regions more likely to be contaminated and to assess how to take this variability into account in environmental assessment. While concentrations were higher in benthic and demersal piscivores, PCB and PCDD/F concentrations (lipid-weight) were similar in most teleost species. For Cd, Hg and Pb, the trophic group accumulating the highest concentrations depended on the contaminant and region. Concentrations in Hg, PCBs and PCDD/Fs were higher in the EEC and/or GoL than in BoB. Cadmium and Pb concentrations were highest in the BoB. Lipid content accounted for 35%-84% of organic contaminant variability. Lipid normalisation was employed to enhance robustness in the identification of spatial patterns. Contaminant patterns in chondrichthyans clearly differed from that in teleosts. In addition, trophic levels accounted for ≤1% and ≤33% of the contaminant variability in teleost fishes in the EEC and BoB, respectively. Therefore, developing taxa-specific thresholds might be a more practical way forward for environmental assessment than normalisation to trophic levels.

Comprehensive non-target screening of biomagnifying organic contaminants in the Baltic Sea food web

High-resolution mass spectrometry (HRMS) based non-target screening (NTS) is a powerful approach for the simultaneous determination of multiple environmental contaminant classes in complex biota samples. In this study, trophic biomagnification factor (TMF) directed NTS was performed to find and (tentatively) identify known, emerging, and new chemical contaminants that are persistent and biomagnify in Baltic Sea biota. The investigated food web included seven species: one filter feeder (blue mussel, Mytilus edulis), two fish (eelpout, Zoarces viviparous; herring, Clupea harengus), two marine mammals (harbor porpoise, Phocoena phocoena; grey seal, Halichoerus grypus) and two birds (guillemot, Uria aalge; white-tailed sea eagle, Haliaeetus albicilla). The NTS procedure included extraction with organic solvent mixtures, two-step high-resolution gel permeation chromatography clean-up, Florisil® fractionation, gas chromatography (GC) HRMS analysis in electron ionization (EI) and electron capture negative ion chemical ionization (ECNI) modes, and NTS data processing. The latter was performed differently for the EI and ECNI data: the EI data were treated using a flexible and highly automated TMF-directed NTS workflow, whereas the ECNI data were treated with a simpler and less automated workflow that specifically screened for brominated compounds. The two workflows collectively revealed biomagnification (statistically significant TMF values) of >250 tentatively identified compounds, including legacy persistent organic pollutants (POPs), such as PCBs and PCB-related compounds, DDT and its metabolites, and organochlorine pesticides (OCPs), contaminants of emerging concern (CECs), and halogenated natural products (HNPs). Among the tentatively identified CECs, nine have not previously been reported in environmental biota samples. These included four polymer additives (used as antioxidants, rubber additives or plasticizers) and two cosmetic product additives (ethyl myristate and isopropyl palmitate). The CECs should be prioritized for future structure verification and quantification using reference standards.

A Review of Hydroxylated and Methoxylated Brominated Diphenyl Ethers in Marine Environments

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) and methoxylated polybrominated diphenyl ethers (MeO-PBDEs) are present in the marine environment worldwide. Both OH-PBDEs and MeO-PBDEs are known natural products, whereas OH-PBDEs may also be metabolites of PBDEs. There is growing concern regarding OH-PBDEs as these compounds seem to be biological active than PBDEs. In the present study, we reviewed the available data on the contamination of OH/MeO-PBDEs in the marine environment worldwide, including seawater, marine sediment, marine plants, invertebrates, fish, seabirds and mammals. Bioaccumulation and biomagnification of OH/MeO-PBDEs in the marine food web were summarized as well. This study also proposes the future research of OH/MeO-PBDEs, including the production and the synthesis pathway of OH/MeO-PBDEs, the toxicokinetics of OH/MeO-PBDEs and the toxicology and human exposure risk assessment.

Bioaccumulation and trophic transfer of PAHs in tropical marine food webs from coral reef ecosystems, the South China Sea: Compositional pattern, driving factors, ecological aspects, and risk assessment

Multiple environmental pressures caused by global warming and human activities have aroused widespread concern about PAHs pollution in tropical marine coral reef regions (CRRs). However, the trophodynamics of PAHs in the food webs of the CRRs and the related influence factors have not been reported. This study investigated the occurrence, trophic amplification, and transmission of PAHs in various organisms selecting between at least representative species for each level in CRRs of the South China Sea (SCS); revealed their driving mechanisms; and explored the trophodynamics of PAHs in the food web of the coral reef ecosystem. Results showed that more PAHs can be accumulated in the mantle tissue of Tridacnidae, and the proportion of mantle tissue of Tridacnidae increases with the increase of latitude (y = 0.01x + 0.17, R² = 0.49, p < 0.05). Latitude drives the differential occurrence level and bioaccumulation of PAHs in tropical marine organisms, and also affects the trophodynamics of PAHs in aquatic ecosystem food webs. PAHs undergo trophic amplification in the food webs of tropical marine ecosystems represented by coral reefs, thus further aggravating the negative environmental impact on coral reef ecosystems. The cancer risk caused by accidental ingestion of PAHs by humans through consumption of seafood in CRRs is very low, but we should be alert to the biomagnification effect of PAHs.

A large diversity of organohalogen contaminants reach the meso- and bathypelagic organisms in the Bay of Biscay (northeast Atlantic)

Deep-sea ecosystems play a key role in the cycling and vertical transfer of matter and energy in oceans. Although the contamination of deep-sea demersal and benthic organisms by persistent organic pollutants has been proven, deep pelagic species have been far less studied. To fill these gaps, we studied the occurrence of a large variety of hydrophobic organic contaminants including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), legacy and alternative brominated flame retardants (BFRs) and per- and polyfluoroalkyl substances (PFASs) in crustaceans and fish species collected in the Bay of Biscay, northeast Atlantic. The results highlighted the global predominance of PCBs in fish, followed by OCPs, PFASs and PBDEs, with highly variable concentrations among species. Most of the chlorinated or brominated contaminants showed increasing concentrations with increasing δ¹⁵N values, while most PFASs showed inverse trends. The contaminant profiles and diagnostic ratios revealed species-specific metabolic capacities and peculiar contribution of highly-brominated BFRs.

Bioamplification and Biomagnification of Polycyclic Aromatic Hydrocarbons and Halogenated Organic Pollutants in Moths from an Electronic Waste Recycling Site

Samples of Asota caricae (larvae, pupae, and adults) and its host plant leaf (Ficus hispida), larvae of Aloa lactinea, and mixed adult moths were collected from an electronic waste (e-waste) recycling site in south China. Polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and polybrominated diphenyl ethers were found to exhibit concentrations of 420-1300, 100-860, and 7.6-49 ng/g dry weight, respectively. The different chemical compositions among the samples of the three groups indicated that at least two exposure scenarios occurred among the moths in the study area. A complex relationship between bioamplification factors and the octanol-water partition coefficient (log K_OW ) was observed during metamorphosis, in which a positive relationship was evident for 5 < log K_OW  < 7, whereas an inverse relationship occurred for log K_OW values outside of this range. The biomagnification factors (BMFs) calculated from the larvae of Asota caricae to the host plant were negatively correlated with log K_OW for all chemicals, differing completely from those obtained in previous studies. However, after metamorphosis, the correlation between BMF and log K_OW was found to coincide with that in previous studies. These results indicate that the biotransformation of pollutants in organisms played a key role in determining whether or not biomagnification occurred in organisms and highlight the potential application of the metabolic rate of chemicals in screening-level risk assessments of new chemicals. Environ Toxicol Chem 2022;41:2395-2403. © 2022 SETAC.

Biomagnification of Persistent Organic Pollutants from Terrestrial and Aquatic Invertebrates to Songbirds: Associations with Physiochemical and Ecological Indicators

Biomagnification of persistent organic pollutants (POPs) is affected by physiochemical properties of POPs and ecological factors of wildlife. In this study, influences on species-specific biomagnification of POPs from aquatic and terrestrial invertebrates to eight songbird species were investigated. The median concentrations of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in birds were 175 to 13 200 ng/g lipid weight (lw) and 62.7 to 3710 ng/g lw, respectively. Diet compositions of different invertebrate taxa for songbird species were quantified by quantitative fatty acid signature analysis. Aquatic insects had more contributions of more hydrophobic POPs, while terrestrial invertebrates had more contributions of less hydrophobic PCBs in songbirds. Biomagnification factors (BMFs) and trophic magnification factors had parabolic relationships with log K_OW and log K_OA. The partition ratios of POPs between bird muscle and air were significantly and positively correlated with log K_OA of POPs, indicating respiratory elimination as an important determinant in biomagnification of POPs in songbirds. In this study, the species-specific biomagnification of POPs in songbird species cannot be explained by stable isotopes of carbon and nitrogen and body parameters of bird species. BMFs of most studied POPs were significantly correlated with proportions of polyunsaturated fatty acids in different species of songbirds.

Exploring the partitioning of hydrophobic organic compounds between water, suspended particulate matter and diverse fish species in a German river ecosystem

BACKGROUND

Bioaccumulation of hydrophobic organic compounds (HOCs) along freshwater food chains is a major environmental concern as top predators in food webs are relevant for human consumption. To characterize and manage the associated risks, considerable numbers of organisms are sampled regularly for monitoring purposes. However, ethical and financial issues call for an alternative, more generic and more robust approach for assessing the internal exposure of fish that circumvents large variability in biota sampling due to interindividual differences. Passive sampling devices (PSDs) offer a fugacity-based approach for pollutant enrichment from different abiotic environmental compartments with a subsequent estimation of bioaccumulation in fish which we explored and compared to HOC concentrations in fish as determined using traditional approaches.

RESULTS

In this study, concentrations in silicone-based PSDs applied to the water phase and suspended particulate matter (SPM) of a river polluted with HOCs were used to estimate the concentration in model lipids at thermodynamic equilibrium with either environmental compartment. For comparison, muscle tissue of seven fish species (trophic level 1.8 to 2.8) was extracted using traditional exhaustive solvent extraction, and the lipid-normalized concentrations of HOCs were determined. The PSD-based data from SPM proved to be a more conservative estimator for HOCs accumulated in fish than those from water. Body length of the fish was found to be more suitable to describe increasing accumulation of HOCs than their trophic level as derived from stable isotope analysis and might offer a suitable alternative for future studies.

CONCLUSIONS

By combining fugacity-based sampling in the abiotic environment, translation into corresponding concentrations in model lipids and body length as an indicator for increasing bioaccumulation in fish, we present a suggestion for a robust approach that may be a meaningful addition to conventional monitoring methods. This approach potentially increases the efficiency of existing monitoring programs without the need to regularly sacrifice vertebrate species.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1186/s12302-022-00644-w.

Passive Sampling Helps the Appraisal of Contaminant Bioaccumulation in Norwegian Fish Used for Regulatory Chemical Monitoring

Hexachlorobenzene (HCB), listed on the Stockholm Convention on persistent organic pollutants and regulated as a hazardous priority pollutant by the Water Framework Directive (WFD), is ubiquitously distributed in the environment and assumed to mildly biomagnify in aquatic foodwebs. The proposal to include trophic magnification factors (TMFs) in the procedure for comparing contaminant levels in biota at different trophic levels (TLs) with WFD environmental quality standards requires adequate selection of TMFs. In the first step of our study, we compared two independently obtained datasets of pentachlorobenzene (PeCB) and HCB concentration ratios from passive sampling (PS) in water and in fish through routine monitoring programs in Norway to evaluate possible biomagnification. In this procedure, PeCB is used for benchmarking the bioconcentration in fish, and the observed HCB/PeCB ratios in fish are compared with ratios expected in the case of (i) HCB bioconcentration or (ii) biomagnification using published TMF values. Results demonstrate that it is not possible to confirm that HCB biomagnifies in fish species that would be used for WFD monitoring in Norway and challenges the proposed monitoring procedures for such compounds in Norwegian or European waters. In the second step, fish-water chemical activity ratios for HCB and PeCB as well as for polychlorinated biphenyls where biota and PS were conducted alongside were calculated and found to rarely exceed unity for cod (Gadus morhua), a fish species with a TL of approximately 4.