Abundant use of plastic materials has increased the amount of microplastics (MPs) and related hazardous chemicals in the marine environment. Hexabromocyclododecanes (HBCDs), brominated flame retardants added to expanded polystyrene (EPS), have been detected in biotic and abiotic samples. In this study, the partition constants of HBCDs between plastics and seawater (KPₛw) were determined. Fugacities of HBCDs in EPS, seawater, sediment, and mussels were obtained to determine the directions of the diffusive flux. The fugacities in EPS (fEPS) were greater than those in seawater (fₛw), sediment (fₛₑd), and mussels (fₛwₘᵤₛₛₑₗ₋EPS and fₘᵤₛₛₑₗ₋ᵣₒcₖ) by three orders of magnitude, indicating that EPS plastics are a significant source of HBCDs. The fₘᵤₛₛₑₗ₋ᵣₒcₖ of α-HBCD in rock mussels was greater than fₛw by factors of 1.7, whereas the fₘᵤₛₛₑₗ₋ᵣₒcₖ of γ-HBCD was smaller than fₛw by factors of 16, indicating the bioisomerization from γ-to α-HBCD. The relatively constant concentration ratio of β-HBCD to the total HBCDs indicated that β-HBCD is a sufficient tracer for determining the diffusive flux. The fₛₑd values of HBCDs were greater than fₛw by factors of 17–28, implying a probable advective vertical flow of HBCDs from the EPS plastics, which requires further investigation.

The green turtle (Chelonia mydas) is listed as a globally endangered species and is vulnerable to anthropogenic threats, including environmental pollution. This study investigated the antimicrobial resistance of Gram-negative bacteria isolated from wild green turtles admitted to a sea turtle rehabilitation center in Taiwan. For this investigation, cloacal and nasal swab samples were collected from 28 green turtles between 2018 and 2020, from which a total of 47 Gram-negative bacterial isolates were identified. Among these, Vibrio spp. were the most dominant isolate (31.91%), and 89.36% of the 47 isolates showed resistance to at least one of 18 antimicrobial agents tested. Isolates resistant to one (6.38%), two (8.51%), and multiple (74.47%) antimicrobials were observed. The antimicrobial agents to which isolates showed the greatest resistance were penicillin (74.47%), followed by spiramycin, amoxicillin, and cephalexin. The antimicrobial-resistance profiles identified in this study provide useful information for the clinical treatment of sea turtles in rehabilitation facilities. The results of our study also imply that wild green turtles may be exposed to polluting effluents containing antimicrobials when the turtles traverse migratory corridors or forage in feeding habitats. To benefit sea turtle conservation, future research should focus on (1) how to prevent pollution from antimicrobials in major green turtle activity areas and (2) identifying sources of antimicrobial-resistant bacterial strains in coastal waters of Taiwan.

Excessive nutrient discharges have resulted in pervasive water pollution and aquatic eutrophication. China has made massive efforts to improve water quality since 2000. However, how long-term policy interventions govern external and internal fluxes as well as nitrogen (N) concentrations is not well known. Here we examined the historical N concentration change and its key drivers in eutrophic Lake Dianchi (southwest China) over the period 2002–2018, based on monthly observations of water quality and external N fluxes, local surveys of mitigation measures, and process-based model simulations of internal N fluxes. Our data indicated that N concentrations peaked at 3.0 mg L⁻¹ in 2007–2010 but afterwards declined down to 1.2 mg L⁻¹ in 2018. Compared with 2010, the decline in lake N concentrations was attributed to reduced riverine N inflow decreasing by 0.20 g N m⁻³ month⁻¹ and the water-sediment exchange flux decreasing by 0.07 g N m⁻³ month⁻¹ from 2010 to 2018. Adoptions of wastewater treatment, pollution interception, and transboundary water transfer dominated the changes in external and internal fluxes of N and thereby the decline of lake N concentrations. These findings underscore the priority of reducing external discharge for historical lake water quality improvement and the need of enhancing internal N removal for future lake ecosystem restoration.

Accumulation of metals by plants is an important area of investigation in plant ecology and evolution as well as in soil contamination/phytoremediation practices. This paper reports that hormetic-biphasic dose-response relationships were commonly observed for multiple agents (i.e. arsenic, cadmium, chromium, fluoride, lead, and zinc) and 20 species in plant (hyper)accumulator studies. The hormetic stimulation was related to metal accumulation in affected tissues, with the metal stimulation concentration zone unique for each metal, species, tissue, and endpoint studied. However, quantitative features of the hormetic dose response were similar across all (hyper)accumulation studies, with results independent of plant species, endpoints measured, and metal. The dose-dependent stimulatory and inhibitory/toxic plant responses were often associated with the up- and down-regulation of adaptive mechanisms, especially those involving anti-oxidative enzymatic processes. These findings provide a mechanistic framework to account for both the qualitative and quantitative features of the hormetic dose response in plant (hyper)accumulator studies.

Isoflavones (ISOs) are naturally occurring endocrine-disrupting compounds. Few human studies have evaluated the effects of ISO exposure on neonatal anthropometry. This study aimed to examine the associations of maternal soy product consumption and urinary ISO concentrations, including genistein, daidzein, glycitein, and equol, with neonatal anthropometry, based on a Chinese cohort study. In Shanghai-Minhang Birth Cohort Study, pregnant women at 12–16 weeks of gestation were recruited, and they completed a structured questionnaire to assess soy product consumption during pregnancy. They also provided a single spot urine sample for the ISO assay. Neonatal anthropometric indices (birth weight; arm, waist, and head circumference; and triceps, back, and abdominal skinfold thickness) were measured at birth. Multivariable linear regression analysis was performed among the 1188 mother-infant pairs to examine the associations between maternal soy product consumption and neonatal anthropometry. The same statistical model was applied to examine the associations between maternal ISO exposure and neonatal anthropometry among 480 mother-infant pairs. Neonate girls born to mothers who “sometimes” and “frequent” consumed soy products had 169.1 g (95% confidence interval [CI], −68.9–407.1) and 256.5 g (95% CI, 17.1–495.8) higher birth weight, respectively, than those born to mothers who “never” consumed soy products during pregnancy. We observed consistent associations between higher maternal urine ISO concentrations and increased anthropometric indices (birth weight, arm and waist circumference, and triceps and abdominal skinfold thickness) in neonate girls, while no association was observed among boys. The findings suggested that maternal dietary ISO intake during pregnancy is associated with fetal development in a sex-specific pattern. In addition, follow-up studies are required to evaluate whether the observed changes in anthropometric indices at birth are associated with health conditions later in life.

Tea plant is capable of hyper-accumulating fluoride (F) in leaves, suggesting drinking tea may cause excessive F intake in our body and threaten the health. This study investigated the changes in the structure, composition, and F content in the leaf cell wall of the tea (Camellia sinensis) under different F conditions to demonstrate the role of cell wall in F enrichment in tea plants. The cell wall was shown as the main part for F accumulation (67%–92%), with most of F distributed in the pectin fraction (56%–71%). With increasing F concentration, a significant increase (p < 0.05) was observed in the F content of cell wall and its components, the level of cell wall metal ions (i.e. Cu, Mg, Zn, Al, Ca, Ba, Mn), as well as the content of total cell wall materials, cellulose, and pectin. Meanwhile, the level of Cu, Mg, Zn, pectin, and cellulose was significantly positively correlated with the F content in the leaf cell wall. F addition was shown to increase the fluorescence intensity of LM19 and 2F4 antibody-labeled low-methylesterified homogalacturonans (HGs), while decrease LM20-labeled high-methylesterified HGs, coupled with an increase in the activity and gene expression of pectin methyl esterases (PMEs) in tea leaves. All these results suggest that F addition can increase pectin content and demethylesterification, leading to increased absorption of metal cations and chelation of F in the cell wall through the action of metal ions.

It is necessary to understand the interactions between different pesticides in ecotoxicology because pesticides never appear as individual compounds but rather in combinations with other compounds. In this study, we planned to explicate the combined toxic effect of myclobutanil (MYC) and thiamethoxam (THI) on the zebrafish (Danio rerio) by adopting multiple biomarkers. Results unraveled that the 96-h LC₅₀ values of MYC to D. rerio at various life phases ranged from 5.2 to 10.3 mg L⁻¹, which were lower than those of THI ranging from 147 to 246 mg L⁻¹. Combinations of MYC and THI exhibited synergetic toxicity to zebrafish embryos. The activities of antioxidative enzymes (T-SOD, Cu/Zn-SOD and POD) and detoxification enzyme (GST) were obviously varied in most of the MYC, THI and combined exposures compared to the control. The mRNA expressions of eight genes (Cu-sod, cas3, il-8, cxcl, erα, crh, cyp17 and dio1) involved in antioxidation, apoptosis, immunity and endocrine were obviously altered in the combined exposure of MYC and THI compared to their individual exposures. Our findings hinted the threats when YMC and THI co-existed, which would be beneficial for the risk assessments of pesticide mixtures.

The majority of experimental studies carried out to date, regarding the effects of pollutants on meiofauna have been conducted by means of closed systems, and rarely using open ones. The current work explored the impact of three Polycyclic Aromatic Hydrocarbons (PAHs), anthracene, pyrene and benzo[a]pyrene, applied alone or combined, on meiobenthic nematodes using both systems. The results revealed that single PAHs impacted the nematofauna similarly in closed or open systems with a higher toxicity observed for benzo[a]pyrene. However, the closed microcosms contaminated with PAHs became organically enriched, resulting in more non-selective deposit feeders and omnivores-carnivores. Taxonomic and functional effects related to combinations of PAHs were close to those of individual treatments in closed systems, however, for open ones, the outcomes were different. The caudal morphology influenced the response of taxa during their avoidance/endurance of hydrocarbons in open systems where the effects of PAHs mixtures appeared not only additive but also synergetic. Based on the results of the study, the use of open systems is preferred to closed ones as the research outcomes were more accurate and representing better conditions prevailing in nature.

Small extracellular vesicles (sEV) are small lipid bilayer particles released by cells. sEV have been shown to play critical roles in intercellular communication. Di (2-ethylhexyl) phthalate (DEHP), widely used as plasticizers, has been detected in the environment and human beings. DEHP was found to exist in the air particles and showed pulmonary toxicity. However, there’s little knowledge about the role of sEV in mediating the toxicity of DEHP-induced lung toxicity. We hypothesized that sEV mediated the toxicity of DEHP through their cargo. To validate this, lung epithelial cells (A549) were exposed to various concentrations (0, 0.2, 2 and 20 μM) of DEHP for 48 h. sEV extracted from DEHP-exposed A549 cells were cultured with unexposed A549 cells. Results showed that DEHP induced the epithelial-mesenchymal transition (EMT) and promoted the migration and invasion ability of A549 cells. The number of released sEV significantly increased in the culture media in DEHP-exposed groups compared to unexposed groups. The sEV can enter the unexposed A549 cells and enhance its EMT and the ability of migration and invasion. Treatment with GW4869 in DEHP-exposed A549 cells almost blocked the effects of DEHP-elicited sEV in normal A549 cells. Sequencing and functional analysis showed that the enrichment of significantly differentially expressed sEV miRNAs were related to tumor etiology. MiR-26a-5p was significantly enriched in DEHP-elicited sEV. Inhibition of miR-26a-5p in DEHP-exposed cells led to the downregulation of miR-26a-5p in sEV, and thus abolished the effects of DEHP-elicited sEV in normal A549 cells, whereas overexpression of miR-26a-5p restored the effects. The transcription factors twist is one of the downstream targets in the effects of sEV-miR-26a-5p on EMT process. In all, our results showed that DEHP exposure promoted the secretion of miR-26a-5p in sEV, which subsequently enhanced the EMT, migration and invasion ability in neighboring normal cells via the twist.