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

Bioaccumulation and Transfer of Legacy and Emerging Per- and Polyfluoroalkyl Substances throughout the Lifecycle of a Tropical Amphibian Species Fejervarya limnocharis

Pollutant bioaccumulation in amphibians is complex owing to their unique physiological characteristics and biphasic lifecycle. This study investigated per- and polyfluoroalkyl substances (PFASs) in water, insects, and rice frogs (Fejervarya multistriata) throughout their entire lifecycle. The median total PFAS concentrations were 1.15-5.53, 65.6, 7.31, 7.33, and 2.24-31.6 ng/g dry weight in insect, egg, tadpole, juvenile frog, and adult frog samples, respectively. Concentrations of PFASs with protein-water distribution coefficients (log KPW) > 2 decreased from eggs to tadpoles and were constant from tadpoles to frogs. By contrast, concentrations of PFASs with log KPW < 2 reached apex concentrations in tadpoles and juvenile frogs. No growth dilution was observed for PFASs from juvenile to adult frogs. Stable isotope and fatty acid compositions in frog and insect samples indicated little change in diet sources during frog growth. The bioaccumulation factors of PFASs with log KPW < 3 were decreased in tadpoles and frogs, suggesting preferential accumulation of low-proteinphilic PFASs from water. The distinct bioaccumulation profiles of PFASs during rice frog development emphasize the need for ecological and toxicological studies conducted throughout the amphibian lifecycle.

Regional pollution and diet drive organohalogen contaminant accumulation in mangrove-settled spiders (Nephila pilipes)

Mangrove-settled spiders play a crucial role in maintaining the ecological balance of mangrove wetlands, yet organohalogen contaminants (OHCs) pose a significant threat to these species. This study evaluated the dietary composition (including 15 insect species) and OHC accumulation in Nephila pilipes, a dominant spider species, across two mangrove habitats, using data from 80 OHCs and quantitative fatty acid signature analysis (QFASA). Dichlorodiphenyltrichloroethane (DDT) accounted for over 50 % of the total OHCs in both spiders and insects, followed by polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), alternative halogenated flame retardants (AHFRs), and hexachlorocyclohexane (HCHs). Biomagnification and trophic magnification patterns of OHCs were consistent across both mangroves, suggesting that spatial variability did not significantly influence overall biomagnification. Carnivorous insects exhibited lower proportions of tetra- and penta-BDEs compared to phytophagous insects but had significantly higher total OHC concentrations. The presence of carnivorous insects, such as the ditch jewel, in the spider diet was negatively correlated with phytophagous insects, such as the common emigrant and tobacco cutworm, suggesting potential niche exclusivity. Spiders from more polluted mangroves accumulated higher OHC concentrations, with carnivorous insects contributing 64.9 ± 3.90 % and 67.9 ± 5.79 % to the total OHC load in Zhuhai and Shenzhen, respectively. The regional differences in OHC concentrations were primarily attributed to higher background pollution levels in Shenzhen rather than dietary composition alone. This study highlights the influence of regional pollution on OHC accumulation in mangrove spiders and underscores the importance of region-specific dietary assessments for accurate pollutant bioaccumulation evaluations.

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.

Occurrence, Bioaccumulation, and Trophic Transfer of Short-Chain Chlorinated Paraffins (SCCPs) in a Marine Food Web from Laizhou Bay, Bohai Sea (Eastern China)

Short-chain chlorinated paraffins (SCCPs) are a persistent organic pollutant, and limited information is available on their bioaccumulation and trophic transfer, which would be affected by carbon chain length, chlorine content, and hydrophobicity. In this study, relevant data on SCCPs in water, sediments, and organisms collected from Laizhou Bay were analyzed to investigate the specific distribution of SCCPs and their bioaccumulation and trophic transfer. In water and sediments, the average SCCP concentrations (ΣSCCPs) were 362.23 ± 81.03 ng/L and 609.68 ± 90.28 ng/g d.w., respectively. In 28 species of organisms, the ΣSCCPs varied from 70.05 to 47,244.13 ng/g l.w. (average = 648 ± 7360) and the predominant homologs were C13 (average = 34.91%) and Cl5-7 (average = 93.13%), differing from those in water (average = C11 32.75% and average = Cl5-7 88%) and sediments (average = C13 31.60% and average = Cl6-8 87.16%). The logarithm bioaccumulation factors (BAFs) of ΣSCCPs were 1.18-2.74 and were positively correlated with the log Kow. A significant negative linear relationship was observed between biota-sediment accumulation factors (BSAFs) and log Kow. It is suggested that the hydrophobicity may affect the bioaccumulation of SCCPs. SCCPs demonstrated a trophic magnification factor (TMF) ranging from 2.19 to 3.00 (average = 2.51) and exhibited a significant linear correlation with carbon chain length (p < 0.05) and log Kow values (p < 0.05), suggesting that SCCPs have biomagnification potential in Laizhou Bay that is affected by hydrophobicity and carbon chain length.

Impact of organic contaminants in soils from Important Bird and Biodiversity areas

Soils act as sinks for many organic contaminants, posing a threat to biodiversity and essential ecosystem services. In this study, we assessed the contamination status of soils in 140 Important Bird and Biodiversity Areas (IBAs) in Spain. Fifty-two organic contaminants including organochlorine pesticides (OCPs), organophosphorus pesticides (OPPs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and plasticizers or plastic related such as phthalates, bisphenol A, nonylphenol, and organophosphate esters (OPEs) were analyzed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). The mean soil concentration ranged from 1.41 to 917 ng/g and plasticizer and PAHs were detected at the highest concentrations, while OCPs were the most frequently detected. Hierarchical clustering on principal components (HCPC) and land use data associated PCBs with artificial land, phthalates with industrial sites and incineration plants and PAHs with burned areas, and in a lesser extent pesticides with agricultural activities. A tier I environmental risk assessment (ERA) was performed to identify the most impacted natural areas and the most concerning compounds. Out of the 140 IBAs, 95 presented at least one compound at high-risk concentrations (RQ > 1) for soil organisms. The OPPs chlorpyrifos and malathion, together with the PAH benzo[b]fluoranthene, were detected at high-risk concentrations. Overall, this study highlights the widespread presence of organic contaminants in areas of high natural value and the importance of implementing monitoring studies to identify potential contaminated sites that require conservation and remediation actions for the protection of biodiversity.

Microplastics' vector effect on Co-bioaccumulation of it and polychlorinated biphenyls in Crassostrea hongkongensis

Microplastics (MPs) and polychlorinated biphenyls (PCBs) are known with high persistence and toxicity, posing urgent threats to food safety and human health. However, little is known about the synergistic effect of MPs on PCBs bioaccumulation on Crassostrea hongkongensis. In the present study, diverse types of MPs were analyzed on sea water and C. hongkongensis sampled from three distinct estuary sites, and film-shaped MPs were discovered to be preferentially ingested by the oysters. Interestingly, the content of MPs and PCBs showed negative correlation (R2 = 0.452, p< 0.001) in the oysters sampled from site 2. Upon MPs and PCBs co-treatment, the in vivo accumulation of PCBs in C. hongkongensis was inhibited by 25.90 % when compared to the group treated with PCBs solely. PCBs stresses significantly induced the expression of genes of CYP2C31, GST, SOD and HSP70 in C. hongkongensis, while, the elevated state was compromised when co-treated with PCBs. The present research alleviates concerns about the potential effects of MPs on promoting PCBs bioaccumulation and provide a better understanding of the combined impact of MPs and PCBs on C. hongkongensis.

Persistent organic pollutants in feathers of various terrestrial and aquatic bird species: Interspecies difference and source apportionment

Feathers are regarded as important nondestructive biomonitoring tools for bird pollutants. However, external contamination of feathers by different pollutants in different bird species remains unclear. In the present study, the feathers of 16 bird species, including terrestrial, freshwater, and marine birds, were analyzed for persistent organic pollutants (POPs). Bird feathers from an abandoned e-waste recycling site had higher POP concentrations and were more correlated with the POP muscle concentrations than those from the less polluted areas. The significant and positive POP correlations between the feathers and muscles of different species indicate that feathers are a good indicator of inter-species and spatial pollution. For individual species, the most hydrophobic POPs in feathers, such as hepta- to deca-polybrominated diphenyl ethers, had higher proportions than in muscles and worse correlations with muscle POPs compared with other POPs. Results of the chemical mass balance (CMB) model revealed that the gaseous phase, internal pollution, and atmospheric particle phase were the main contributors to low-, medium-, and high-hydrophobicity POPs in feathers, respectively. Overall, this study provides a preliminary but meaningful framework for distinguishing between internal and external contamination in feathers and gives information concerning the fitness of feathers as POP indicators with specific physicochemical properties.

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.

Mechanistic and data-driven perspectives on plant uptake of organic pollutants

Establishing reliable predictive models for plant uptake of organic pollutants is crucial for environmental risk assessment and guiding phytoremediation efforts. This study compiled an expanded dataset of plant cuticle-water partition coefficients (Kcw), a useful indicator for plant uptake, for 371 data points of 148 unique compounds and various plant species. Quantum/computational chemistry software and tools were utilized to compute various molecular descriptors, aiming to comprehensively characterize the properties and structures of each compound. Three types of models were developed to predict Kcw: a mechanism-driven pp-LFER model, a data-driven machine learning model, and an integrated mechanism-data-driven model. The mechanism-data-driven GBRT-ppLFER model exhibited superior performance, achieving RMSEtrain = 0.133 and RMSEtest = 0.301 while maintaining interpretability. The Shapley Additive Explanation analysis indicated that pp-LFER parameters, ESPI, FwRadicalmax, ExtFP607, and RDF70s are the key factors influencing plant uptake in the GBRT-ppLFER model. Overall, pp-LFER parameter, ESPI, and ExtFP607 show positive effects, while the remaining factors exhibit negative effects. Partial dependency analysis further indicated that plant uptake is not solely determined by individual factors but rather by the combined interactions of multiple factors. Specifically, compounds with ppLFER parameter >4, ESPI > -25.5, 0.098 < FwRadicalmax <0.132, and 2 < RFD70s < 3, are generally more readily taken up by plants. Besides, the predicted Kcw values from the GBRT-ppLFER model were effectively employed to estimate the plant-water partition coefficients and bioconcentration factors across different plant species and growth media (water, sand, and soil), achieving an outstanding performance with an RMSE of 0.497. This study provides effective tools for assessing plant uptake of organic pollutants and deepens our understanding of plant-environment-compound interactions.

Organochlorine pesticides in Ethiopian waters: Implications for environmental and human health

Despite the global ban on organochlorine pesticides (OCPs) since the 1970s, their use continues in many developing countries, including Ethiopia, primarily due to the lack of viable alternatives and weak regulations. Nonetheless, the extent of contamination and the resulting environmental and health consequences in these countries remain inadequately understood. To address these knowledge gaps, we conducted a comprehensive analysis of reported concentrations (n=398) of OCPs (n=30) in distinct yet interconnected water matrices: water, sediment, and biota in Ethiopia. Our analysis revealed a notable geographical bias, with higher concentrations found in sediments (0.074-1161.2 µg/kg), followed by biota (0.024-1003 µg/kg) and water (0.001-1.85 µg/L). Moreover, DDTs, endosulfan, and hexachlorohexenes (HCHs) were among the most frequently detected OCPs in higher concentrations in Ethiopian waters. The DDT metabolite p,p'-DDE was commonly observed across all three matrices, with concentrations in water birds reaching levels up to 57 and 143,286 times higher than those found in sediment and water, respectively. The findings showed a substantial potential for DDTs and endosulfan to accumulate and biomagnify in Ethiopian waters. Furthermore, it was revealed that the consumption of fish contaminated with DDTs posed both non-carcinogenic and carcinogenic risks while drinking water did not pose significant risks in this regard. Importantly, the issue of OCPs in Ethiopia assumes even greater significance as their concentrations were found to be eight times higher than those of currently used pesticides (CUPs) in Ethiopian waters. Consequently, given the ongoing concerns about OCPs in Ethiopia, there is a need for ongoing monitoring, implementation of sustainable mitigation measures, and strengthening of OCP management systems in the country, as well as in other developing countries with similar settings and practices.

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.

PCB169 exposure aggravated the development of non-alcoholic fatty liver in high-fat diet-induced male C57BL/6 mice

Polychlorinated biphenyls (PCBs) are lipophilic environmental toxicants. Epidemiological studies have established a link between PCBs and both metabolic syndrome and nonalcoholic fatty liver disease (NAFLD). Multiple studies have reported that exposure to both PCB156 and PCB126 among the 12 dioxin-like PCBs leads to the development of NAFLD. However, studies to elucidate whether PCB169 induces the development of NAFLD by constructing in vivo models have not been reported. Therefore, we evaluated the effects of exposure to PCB169 (5 mg/kg-bw) on hepatic lipid metabolism in C57BL/6 mice from control diet and high-fat diet cohorts. The results showed that PCB169 exposure reduced body weight and intraperitoneal fat mass in mice on the control diet, but the liver lipid levels were significantly increased, exacerbating NAFLD in mice on a high-fat diet. Through transcriptomics studies, it was found that PCB169 exposure induced significant up-regulation of Pparγ, Fasn, and Aacs genes involved in hepatic lipogenesis, as well as remarkable up-regulation of Hmgcr, Lss, and Sqle genes involved in cholesterol synthesis. Additionally, there was notable down-regulation of Pparα and Cpt1 genes involved in lipid β-oxidation, leading to abnormal lipid accumulation in the liver. In addition, we found that PCB169 exposure significantly activated the Arachidonic acid metabolism, PPAR signaling pathway, Metabolism of xenobiotics by cytochrome P450, and Retinol metabolism pathways, and so on. Our study suggests that PCB169 can modify gene expression related to lipid metabolism, augument lipid accumulation in the liver, and further contribute to the development of NAFLD, thereby revealing the detrimental effects associated with PCB exposure on animal growth and metabolism.

Developmental toxicity of short-chain chlorinated paraffins on early-stage chicken embryos in a shell-less (ex-ovo) incubation system

Short-chain chlorinated paraffins (SCCPs) are listed as a category of globally controlled persistent organic pollutants (POPs) by the Stockholm Convention in 2017. However, SCCP toxicity, particularly their developmental toxicity in avian embryos, has not been well studied. In this study, we observed the early development of chicken embryos (Gallus gallus domesticus) by applying a shell-less (ex-ovo) incubation system developed in our previous studies. After exposing embryos at Hamburger Hamilton stage (HHS) 1 to SCCPs (control, 0.1% DMSO; SCCPs-L, 200 ng/g; SCCPs-M, 2000 ng/g; SCCPs-H, 20,000 ng/g), we observed the development of embryos from the 3rd to 9th incubation day. Exposure to SCCPs-M and -H induced a significant reduction in survival, with an LD50 of 3100 ng/g on the 9th incubation day. Significant dose-dependent decreases in body length were observed from days 4-9. We also found that SCCPs-H decreased the blood vessel length and branch number on the 4th incubation day. Additionally, SCCPs-H significantly reduced the heart rate on the 4th and 5th incubation days. These findings suggest that SCCPs may have potential of developmental and cardiovascular toxicity during the early stages of chicken embryos. Quantitative PCR of the mRNA of genes related to embryonic development showed that SLC16A10 (a triiodothyronine transporter) level decreased in the SCCPs-H group, showing a significant positive correlation with the body length of embryos. THRA level, a thyroid hormone receptor, was significantly decreased in the SCCPs-H group, whereas that of DIO3 level, a deiodinase was significantly increased. These results suggest that SCCPs exposure induces developmental delays via the thyroxine signaling pathway. Analysis of thyroid hormones (THs) in blood plasma also indicated a significant reduction in thyroxine (T4) levels in the SCCPs-H group on the 9th incubation day of embryos. In conclusion, SCCPs induce developmental toxicity by disrupting thyroid functions at the early-life stage of chicken embryos.

Investigating the levels, spatial distribution, and trophic transfer patterns of short-chain chlorinated paraffins in the Southern Bohai Sea, China

The marine environment of the southern Bohai Sea is severely polluted by short-chain chlorinated paraffins (SCCPs). To improve understanding of how SCCPs occur and of how they migrate, are transformed, and transferred in this area, we collected seawater, sediment, and organism samples, and determined the SCCP contents using a new approach based on high-resolution mass spectrometry. The ΣSCCP concentrations in the seawater, sediment, and organism samples ranged from 57.5 to 1150.4 ng/L, 167.7-1105.9 ng/g (dry weight), and 11.4-583.0 ng/g (wet weight), respectively. Simulation of the spatial distribution of SCCPs using Kriging interpolation showed that SCCPs were markedly influenced by land-based pollution. Substantial quantities of SCCPs were transported to the marine environment via surface runoff from rivers that passed through areas of major SCCP production. Once discharged from such rivers into the Bohai Sea, these SCCPs were further dispersed under the influence of ocean currents. Furthermore, the logarithmic bioaccumulation factor that varied from 2.12 to 3.20 and the trophic magnification factor that reached 5.60 (r2 = 0.750, p < 0.01) suggest that organisms have the ability to accumulate and biomagnify SCCPs through the food chain, which could potentially present risks to both marine ecosystems and human health.

Proteomic analysis of the hepatic response to a pollutant mixture in mice. The protective action of selenium

Metals and pharmaceuticals contaminate water and food worldwide, forming mixtures where they can interact to enhance their individual toxicity. Here we use a shotgun proteomic approach to evaluate the toxicity of a pollutant mixture (PM) of metals (As, Cd, Hg) and pharmaceuticals (diclofenac, flumequine) on mice liver proteostasis. These pollutants are abundant in the environment, accumulate in the food chain, and are toxic to humans primarily through oxidative damage. Thus, we also evaluated the putative antagonistic effect of low-dose dietary supplementation with the antioxidant trace element selenium. A total of 275 proteins were affected by PM treatment. Functional analyses revealed an increased abundance of proteins involved in the integrated stress response that promotes translation, the inflammatory response, carbohydrate and lipid metabolism, and the sustained expression of the antioxidative response mediated by NRF2. As a consequence, a reductive stress situation arises in the cell that inhibits the RICTOR pathway, thus activating the early stage of autophagy, impairing xenobiotic metabolism, and potentiating lipid biosynthesis and steatosis. PM exposure-induced hepato-proteostatic alterations were significantly reduced in Se supplemented mice, suggesting that the use of this trace element as a dietary supplement may at least partially ameliorate liver damage caused by exposure to environmental mixtures.

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.

Application of amino acids nitrogen stable isotopic analysis in bioaccumulation studies of pollutants: A review

Accurately quantifying trophic positions (TP) to describe food web structure is an important element in studying pollutant bioaccumulation. In recent years, compound-specific nitrogen isotopic analysis of amino acids (AAs-N-CSIA) has been progressively applied as a potentially reliable tool for quantifying TP, facilitating a better understanding of pollutant food web transfer. Therefore, this review provides an overview of the analytical procedures, applications, and limitations of AAs-N-CSIA in pollutant (halogenated organic pollutants (HOPs) and heavy metals) bioaccumulation studies. We first summarize studies on the analytical techniques of AAs-N-CSIA, including derivatization, instrumental analysis, and data processing methods. The N-pivaloyl-i-propyl-amino acid ester method is a more suitable AAs derivatization method for quantifying TP. The AAs-N-CSIA application in pollutant bioaccumulation studies (e.g., Hg, MeHg, and HOPs) is discussed, and its application in conjunction with various techniques (e.g., spatial analysis, food source analysis, and compound tracking techniques, etc.) to research the influence of pollutant levels on organisms is summarized. Finally, the limitations of AAs-N-CSIA in pollutant bioaccumulation studies are discussed, including the use of single empirical values of β_glu/phe and TDF_glu/phe that result in large errors in TP quantification. The weighted β_glu/phe and the multi-TDF_glu/phe models are still challenging to solve for accurate TP quantification of omnivores; however, factors affecting the variation of β_glu/phe and TDF_glu/phe are unclear, especially the effect of pollutant bioaccumulation in organisms on internal AA metabolic processes.

Biomagnification and elimination effects of persistent organic pollutants in a typical wetland food web from South China

This study investigated the quantitative sources of persistent organic pollutants (POPs), their biomagnification factors, and their effect on POP biomagnification in a typical waterbird (common kingfisher, Alcedo atthis) food web in South China. The median concentrations of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in kingfishers were 32,500 ng/g lw and 130 ng/g lw, respectively. The congener profiles of PBDEs and PCBs showed significant temporal changes because of the restriction time points and biomagnification potential of different contaminants. The concentrations of most bioaccumulative POPs, such as CBs 138 and 180 and BDEs 153 and 154, decreased at lower rates than those of other POPs. Pelagic fish (metzia lineata) and benthic fish (common carp) were the primary prey of kingfishers, as indicated by quantitative fatty acid signature analysis (QFASA) results. Pelagic and benthic prey species were the primary sources of low and high hydrophobic contaminants for kingfishers, respectively. Biomagnification factors (BMFs) and trophic magnification factors (TMFs) had parabolic relationships with log K_OW, with peak values of approximately 7. Significant negative correlations were found between the whole-body elimination rates of POPs in waterbirds and the log-transformed TMFs and BMFs, indicating that the strong metabolism of waterbirds could potentially affect POP biomagnification.

Levels and diverse composition profiles of chlorinated paraffins in indoor dust: possible sources and potential human health related concerns

Chlorinated paraffins (CPs), a group of mixtures with different carbon chain lengths and chlorine contents, are widely used as plasticizers and flame retardants in various indoor materials. CPs could be released from CP-containing materials into the ambient environment and then enter the human body via inhalation, dust ingestion and dermal absorption, resulting in potential effects on human health. In this study, we collected residential indoor dust in Wuhan, the largest city in central China, and focused on the co-occurrence and composition profiles of CPs as well as the resultant human risk via dust ingestion and dermal absorption. The results indicated that CPs with C_9-40 were ubiquity in indoor dust with medium-chain CPs (MCCPs, C_14-17) as the main components (6.70-495 μg g^-1), followed by short-chain CPs (SCCPs, C_10-13) (4.23-304 μg g^-1) and long-chain (LCCPs, C_≥18) CPs (3.68-331 μg g^-1). Low levels (not detected-0.469 μg g^-1) of very short-chain CPs (vSCCPs, C₉) were also found in partial indoor dust. The dominant homolog groups were C₉ and Cl_6-7 groups for vSCCPs, C₁₃ and Cl_6-8 groups for SCCPs, C₁₄ and Cl_6-8 groups for MCCPs, and C₁₈ and Cl_8-9 groups for LCCPs. Based on the measured concentrations, vSCCPs, SCCPs, MCCPs, and LCCPs posed limited human health risks to local residents via dust ingestion and dermal absorption.