Transcription factors including pregnane X receptor (Pxr) and nuclear factor-erythroid 2-related factor-2 (Nrf2) are important modulators of Adenosine triphosphate-binding cassette (ABC) transporters in mammalian cells. However, whether such modulation is conserved in zebrafish embryos remains largely unknown. In this manuscript, pxr- and nrf2-deficient models were constructed with CRISPR/Cas9 system, to evaluate the individual function of Pxr and Nrf2 in the regulation of ABC transporters and detoxification of heavy metal ions like Cd²⁺ and Ag⁺. As a result, both Cd²⁺ and Ag⁺ conferred extensive interactions with ABC transporters in wild type (WT) embryos: their accumulation and toxicity were affected by the activity of ABC transporters, and they significantly induced the mRNA expressions of ABC transporters. These induction effects were reduced by the mutation of pxr and nrf2, but elevations in the basal expression of ABC transporters compensated for the loss of their inducibility. This could be an explanation for remaining transporter function in both mutant models as well as the unaltered toxicity of metal ions in pxr-deficient embryos. However, mutation of nrf2 disrupted the production of glutathione (GSH), resulting in the enhanced toxicity of Cd²⁺/Ag⁺ in zebrafish embryos. In addition, elevated expressions of other transcription factors like aryl hydrocarbon receptor (ahr) 1b, peroxisome proliferator-activated receptor (ppar)-β, and nrf2 were found in pxr-deficient models without any treatment, while enhanced induction of ahr1b, ppar-β and pxr could only be seen in nrf2-deficient embryos after the treatment of metal ions, indicating different compensation phenomena for the absence of transcription factors. After all, pxr-deficient and nrf2-deficient zebrafish embryos are useful tools in the functional investigation of Pxr and Nrf2 in the early life stages of aquatic organisms. However, the compensatory mechanisms should be taken into consideration when interpreting the results and need in-depth investigations.

The bacterial communities and ecological contribution of biofilm-leaves of the Vallisneria natans (VN), Hydrilla verticillata (HV) and artificial plant (AP) settled in sediments with different polluted levels of phenanthrene were investigated by high-throughput sequencing in different growth periods. There was no significant difference among the detected Alpha diversity indices based on three classification, attached surface, spiking concentration and incubation time. While Beta diversity analysis assessed by PCoA on operational taxonomic units (OTU) indicated that bacterial community structures were significantly influenced in order of attached surface > incubation time > spiking concentration of phenanthrene in sediment. Moreover, the results of hierarchical dendrograms and heat maps at genus level were consistent with PCoA analysis. We speculated that the weak influence of phenanthrene spiking concentration in sediment might be related to lower concentration and smaller concentration gradient of phenanthrene in leaves. Meanwhile, difference analysis suggested that attached surface was inclined to influence the rare genera up to significant level than incubation time. In general, the results proved that phenanthrene concentrations, submerged macrophytes categories and incubation time did influence the bacterial community of biofilm-leaves. In turn, results also showed a non-negligible ecological contribution of biofilm-leaves in dissipating the phenanthrene in sediments (>13.2%–17.1%) in contrast with rhizosphere remediation (2.5%–3.2% for HV and 9.9%–10.6% for VN).

Thallium (Tl) is a well-recognized hazardous heavy metal with very high toxicity. It is usually concentrated in sulfide minerals, such as pyrite (FeS₂), sphalerite (ZnS), chalcopyrite (CuS) and galena (PbS). Here, this study was carried out to investigate the indigenous microbial communities via 16S rRNA gene sequence analysis in typical surface sediments with various levels of Tl pollution (1.8–16.1 mg/kg) due to acid mine drainage from an active Tl-containing pyrite mining site in South China. It was found with more than 50 phyla from the domain Bacteria and 1 phyla from the domain Archaea. Sequences assigned to the genera Ferroplasma, Leptospirillum, Ferrovum, Metallibacterium, Acidithiobacillus, and Sulfuriferula manifested high relative abundances in all sequencing libraries from the relatively high Tl contamination. Canonical correspondence analysis further uncovered that the overall microbial community in this area was dominantly structured by the geochemical fractionation of Tl and geochemical parameters such as pH and Eh. Spearman's rank correlation analysis indicated a strong positive correlation between acidophilic Fe-metabolizing species and Tlₜₒₜₐₗ, Tlₒₓᵢ, and Tlᵣₑₛ. The findings clarify potential roles of such phylotypes in the biogeochemical cycling of Tl, which may facilitate the development of in-situ bioremediation technology for Tl-contaminated sediments.

The Hooghly River (HR) estuary is the first deltaic off-shoot of the perennial and transboundary river, Ganga, India. HR receives industrial and domestic waste along with storm-water run-off from Kolkata city and the adjoining districts. Organic micropollutants (OMPs) have been collectively termed for plasticizers, pharmaceuticals and personal care products, which are extensively consumed and disposed in the waste streams. Hence emerging OMPs were investigated to obtain the first baseline data from the Hooghly riverine sediment (HRS) along urban and suburban transects using gas chromatography mass spectrometry (GC-MS). The concentration range of OMPs in the HRS varied between 3 and 519 ng/g for carbamazepine, 5–407 ng/g for non-steroidal anti-inflammatory drugs (NSAIDs), 2–26 ng/g for musk ketone, 2–84 ng/g for triclosan, 2–199 ng/g for bisphenol A (BPA), 2–422 ng/g for plasticizers (phthalic acid esters (PAEs) and bis (2-ethylhexyl) adipate (DEHA)) and 87–593 ng/g for parabens. Carbamazepine concentration in sediment was an useful marker for untreated wastewater in urban waterways. High concentrations of BPA and PAEs in the suburban industrial corridor together with significant correlation between these two type of OMPs (r2 = 0.5; p < 0.01) likely reflect a common source, possibly associated with the plastic and electronic scrap recycling industries. Among all the categories of OMPs, plasticizers seems to exhibit maximum screening level ecological risk through out the study area.

Release of phosphorus (P) from sediment to overlying water has to be dealt with to address algal blooms in eutrophic lakes. In this study, the sediment from the Lake Taihu was amended with lanthanum modified zeolite (LMZ) to reduce P release under different pH, temperature and anaerobic conditions. LMZ performed well, to decreasing P concentration in Lake Taihu water in the presence of sediment. The EPC₀ value, the critical P concentration at which there was neither P adsorption nor P release, was lowered by adding LMZ, suggesting that amendment with LMZ could diminish the risk of P release from the sediment. From the Langmuir isotherm model, the adsorption capacity of phosphate by LMZ was estimated to be 64.1 mgP/g. The LMZ-amended sediment had a higher content of stable P forms (HCl-P and Res-P) and a lower content of P forms with a high (NH₄Cl-P and BD-P) or medium-high (NaOH-P and Org-P) risk of release, when compared with the original sediment. The fractionation simulates conditions which release potentially mobile P which can then be simply re-bound to LMZ. At high pH (>9.0), anaerobic condition or high temperature promoted the liberation of P from sediment. However, P release could be greatly inhibited by LMZ. In addition, although Mn²⁺ and NH₄⁺ ions were released from sediment under the anaerobic condition, the release could also be hindered by adding LMZ. LMZ is a promising P inactivation agent to manage eutrophication in the sediment of Lake Taihu.

The effects of exposure to some environmental chemicals on blood pressure have been determined, but the association between non-occupational exposure to perfluoroalkyl substances (PFASs) and blood pressure in adolescents remains unknown. The association between blood pressure and PFAS concentrations was studied by analysing data from 2251 participants filtered from the population enrolled in the National Health and Nutrition Examination Survey (NHANES) from 2003 to 2012. After adjusting for age, sex, race, BMI, cotinine level, dietary intake of calcium, caloric intake, sodium consumption, potassium consumption and sampling year, we estimated the coefficients (betas) and 95% confidence intervals (CIs) for the relationship between PFAS concentrations and blood pressure with multiple linear regression models. Potential non-linear relationships were assessed with restricted cubic spline models. Blood levels of perfluorooctane sulfonic acid (PFOS) had a strong positive association with diastolic blood pressure (DBP) in adolescents in the linear model, while the result was not significant in the non-linear model. No significant association was observed between the concentration of any other PFASs and blood pressure. According to the fully adjusted linear regression model (P = 0.041), the mean DBP values in boys in the higher PFOS quintile were 2.70% greater than the mean DBP values of boys in the lowest PFOS quintile. Furthermore, serum PFOS concentrations predominantly affected blood pressure in male adolescents compared with female adolescents. These results provide epidemiological evidence of PFOS-related increases in DBP. Further research is needed to address related issues.

Endocrine disrupting compounds (EDCs) are becoming an increasing concern regarding bioaccumulation in aquatic biota. However, the effects of regional pollution levels and specific feeding habits on the bioaccumulation of EDCs in fish are rarely reported. 4-Nonylphenol (4-NP), bisphenol A (BPA), 4-tert-octylphenol (4-t-OP), triclocarban (TCC) and triclosan (TCS) were determined in abiotic compartments [water, sediment, suspended particulate matter (SPM)] and fish with different feeding habits along the Pearl River, China. EDCs in abiotic compartments exhibited significant (p < 0.05) spatial variations, forming five zones clustered based on site-specific EDC concentrations. 4-NP was the dominant compound, contributing 58–98% of the EDCs in fish, followed by BPA (<41%), 4-t-OP (<13%), and TCC and TCS (<4.7%). The concentrations of 4-NP and 4-t-OP, BPA, and TCC and TCS were the highest in brackish carnivorous, planktivorous, and detritivorous fish, respectively. The bioaccumulation factors (BAFs) showed that 4-NP accumulated (BAF > 5000) in all fish except for suck-feeding detritivores, while 4-t-OP and TCC accumulated in filter-feeding planktivores. The concentration of 4-NP in carnivores was significantly higher than that in detritivores, indicating the potential biomagnification of 4-NP along food chains. EDCs in sediment and SPM and those in water were most positively correlated with those in detritivores and planktivores, respectively, suggesting the potential of fish with these two feeding habits to act as bioindicators of EDC pollutants.

The application of biochar in remediation and recovery of heavy metals and/or organic contaminants in water and soil is increasing. However, the adverse effect of biochar to aquatic organisms has not received enough attention. In this study, we conducted a study on the biotoxicity of biochar pyrolyzed from pine needle under oxygen-limited conditions. The toxicity of biochar was expressed with the following endpoints: cell growth, chlorophyll-a (Chl-a), reactive oxygen species (ROS), superoxide dismutase (SOD) content of Scenedesmus obliquus (S. obliquus) and the luminescence of Photobacterium phosphoreum (P. phosphoreum). Here, the effect of free radicals (FRs) contained in biochar was stressed. Our results show that the toxicity of biochar is significantly correlated with the concentration of FRs in biochar particles. Meanwhile, we found the FRs-containing biochar could induce the production of acellular ROS (such as ·OH) in water, which would also induce the production of interior cellular ROS in aquatic organisms. Our findings provide a new insight into the mechanism of toxicity aroused by biochar applications and aid in understanding its potential ecological risk.

Nitrogen (N) deposition poses a severe risk to global terrestrial ecosystems, and managing this threat is an important focus for air pollution science and policy. To understand and manage the impacts of N deposition, we need metrics which accurately reflect N deposition pressure on the environment, and are responsive to changes in both N deposition and its impacts over time. In the UK, the metric typically used is a measure of total N deposition over 1–3 years, despite evidence that N accumulates in many ecosystems and impacts from low-level exposure can take considerable time to develop. Improvements in N deposition modelling now allow the development of metrics which incorporate the long-term history of pollution, as well as current exposure. Here we test the potential of alternative N deposition metrics to explain vegetation compositional variability in British semi-natural habitats. We assembled 36 individual datasets representing 48,332 occurrence records in 5479 quadrats from 1683 sites, and used redundancy analyses to test the explanatory power of 33 alternative N metrics based on national pollutant deposition models. We find convincing evidence for N deposition impacts across datasets and habitats, even when accounting for other large-scale drivers of vegetation change. Metrics that incorporate long-term N deposition trajectories consistently explain greater compositional variance than 1–3 year N deposition. There is considerable variability in results across habitats and between similar metrics, but overall we propose that a thirty-year moving window of cumulative deposition is optimal to represent impacts on plant communities for application in science, policy and management.

The growing production and extensive use of organophosphate flame retardants (OPFRs) have led to an increase in their environmental distribution and human exposure. Developmental toxicity is a major concern of OPFRs' adverse health effects. However, the impact of OPFRs exposure on vascular development and the toxicity pathway for developmental defects are poorly understood. In this study, we investigated the effects of exposure to tris(1,3-dichloro-2-propyl) phosphate (TDCPP), a frequently detected OPFR, on early vascular development, and the possible role of nuclear factor erythroid 2-related factor (Nrf2)-dependent angiogenic pathway in TDCPP's vascular toxicity. TDCPP exposure at 300 and 500 μg/L impeded the growth of intersegmental vessels (ISV), a type of microvessels, as early as 30 hpf. Consistently, a similar pattern of decreased extension and remodeling of common cardinal vein (CCV), a typical macrovessel, was observed in zebrafish at 48 hpf and 72 hpf. Developing vasculature in zebrafish was more sensitive than general developmental parameters to TDCPP exposure. The expression of genes related to VEGF signaling pathway dose-dependently decreased in TDCPP-treated larvae. In in vitro experiments using human umbilical vein endothelial cells (HUVECs), the increased cell proliferation induced by VEGF was suppressed by TDCPP exposure in a dose-dependent fashion. In addition, we found a repression of Nrf2 expression and activity in TDCPP-treated larvae and HUVECs. Strikingly, the application of CDDO-Im, a potent Nrf2 activator, enhanced VEGF and protected against defective vascular development in zebrafish. Our results reveal that vascular impairment is a sensitive index for early exposure to TDCPP, which could be considered in the environmental risk assessment of OPFRs. The identification of Nrf2-mediating VEGF pathway provides new insight into the adverse outcome pathway (AOP) of OPFRs.