Pyrene (Pyr), a widely used tetracyclic aromatic hydrocarbon, enters soil in large quantities and causes environmental pollution due to its production and mining. In order to systematically study the biotoxicity of pyrene to model organisms Eisenia fetida in soil, experiments were carried out from four dimensions: animal, tissue, cell and molecule. Experimental results proved that the mortality rate increased with increasing concentration and time of exposure to pyrene, while the mean body weight and spawning rate decreased. Meanwhile, when the pyrene concentration reached 900 mg/kg, the seminal vesicle and longitudinal muscle of the earthworm showed obvious atrophy. Experimental results at the cellular level showed that pyrene induced cell membrane damage and Ca²⁺ influx triggered mitochondrial membrane depolarization and a surge in ROS levels. Oxidative stress causes damage to proteins and lipids and DNA inside cells. When the mortality rate was 91.67 %, the Olive Tail Movement (OTM) of the comet experiment reached 15. The results of molecular level tests showed that pyrene inhibited the activity of Cu/Zn-superoxide dismutase (Cu/Zn-SOD) mainly by changing the microenvironment and secondary structure of amino acid Tyr 108. The weakened function of direct antioxidant enzymes may be the root cause of the excessive increase of reactive oxygen species (ROS) in cells. The systematic approach used in this study enriches the network of toxic pathways in toxicological studies, and basic data on the biological toxicity of pyrene can provide support for future soil contamination detection.

Biochar amendment has the potential to reduce methylmercury (MeHg) uptake by rice grains in soil-rice ecosystem. Considering that sulfur can strongly bind Hg and thus reduce its bioavailability, S-modified biochar has been used to immobilize Hg in soils. However, whether natural S-enriched biochar can further reduce Hg and MeHg phytoavailability remains unknown. Moreover, the rhizosphere is one of the most important microbial hotspots regulating the pollutant dynamics in terrestrial ecosystems. Therefore, it is of greater practical significance to examine the impact of biochar amendment on MeHg production and phytoavailability in the rhizosphere versus nonrhizosphere. Here, by conducting a pot experiment, we evaluated the efficacy of biochar derived from sulfur-enriched oilseed rape straw to reduce MeHg accumulation in rice. The results demonstrated that: (1) biochar-induced enhancement of chloride ion and sulfate levels in the overlying water and pore water facilitate microbial methylation of Hg and thus MeHg production in rhizosphere soil. (2) biochar amendment increased rhizosphere soil sulfur content and humic acid-like substances, strengthening MeHg binding to soil, and thus reducing grain MeHg levels by 47%–75%. Our results highlight the necessity to applying natural sulfur-rich biochar accompanied with exogenous sulfur to further reduce MeHg phytoavailability.

Groundwater quality monitoring typically employs testing for the presence of E. coli as a fecal indicator of recent ingress of human or animal fecal material. The efficacy of fecal indicator organisms is based on the primary criteria that the organism does not reproduce in the aquatic environment. However, recent studies have reported that E. coli may proliferate (i.e., has adapted to) in the external environment, including soil and surface water. To date, the presence of environmentally-adapted E. coli in groundwater has not been examined. The current study employed Clermont phylotyping and the presence of six accessory genes to identify the likely presence of adapted E. coli in private groundwater sources. E. coli isolates (n = 325) from 76 contaminated private water wells located in a southeastern Ontario watershed were compared with geographically analogous human and animal fecal E. coli isolates (n = 234). Cryptic clades III-V, a well-described environmentally-adapted Escherichia population, were identified in three separate groundwater wells, one of which exclusively comprised this adapted population. Dimensionality reduction (via Principal Component Analysis) was used to develop an “E. coli adaptation model”, comprising three distinct components (groundwater, animal feces, human feces) and suggests adaptation occurs frequently in the groundwater environment. Model findings indicate that 23/76 (30.3%) wells had an entirely adapted community. Accordingly, the use of E. coli as a FIO returned a false positive result in these instances, while an additional 23/76 (30.3%) wells exhibited some evidence of adaptation (i.e., not all isolates were adapted) representing an over-estimate of the magnitude (concentration) of contamination. Study findings highlight the need to further characterize environmentally-adapted E. coli in the groundwater environment and the potential implications with respect to water quality policy, legislation and determinants of human health risk both regionally and internationally.

When assessing oil spills in marine environments, focus has often been on describing degradation and removal of hydrocarbons. However, more and more attention is now given to the formation of mineral oil transformation products, and their potential toxicity and persistency in the environment. The aim of this study was to investigate the formation of dissolved acidic degradation products from crude oil in sea water from the Persian Gulf in a lab-experiment. A super-complex mixture of acidic degradation products was formed in the water phase and compound groups of aliphatic acids, monocyclic aromatic acids-, and polycyclic aromatic acids were identified. More specifically, alkylated PAHs were biodegraded to a high number of aromatic, carboxylic acids by hydroxylation of the alkyl side chains. These degradation products are more bioavailable than their parent compounds, and may therefore constitute a new group of contaminants that should be considered in oil spill assessments.

Per- and polyfluoroalkyl substances (PFASs) are environmentally and biologically persistent anthropogenic chemicals linked to adverse health outcomes. Epidemiological data have revealed association between exposure to specific PFAS and disruption of insulin level in bodies. However, the effect of PFASs on insulin secretion and the responsible molecular mechanism are poorly understood. In the present study, we used perfluorooctane sulfonate (PFOS) as a representative PFAS family member to investigate its effect on the insulin secretion in mouse pancreatic β cells (β-TC-6). Our results showed that exposure to PFOS inhibited silent information regulator 1 (SIRT1) activity, and molecular simulation showed PFOS could fit into the pocket overlapped with the nicotinamide adenine dinucleotide (NAD⁺) binding cavity in SIRT1. PFOS exposure upregulated uncoupling protein 2 (UCP2) expression, and this upregulation was blunted in the presence of Ex-527, a SIRT1 specific inhibitor. The mitochondria membrane potential (ΔΨm), as well as the glucose-induced ATP production and Ca²⁺ influx decreased under PFOS treatment. PFOS continual exposure (48 h) impaired glucose stimulated insulin secretion (GSIS), while the gene expression of insulin was not significantly altered. Importantly, the SIRT1 activator and UCP2 inhibitor could partly reverse the PFOS-induced impairment of GSIS. Taken together, the results suggested that PFOS continual exposure could inhibit SIRT1 activity, and the SIRT1-UCP2 pathway mediated, at least partially, the PFOS induced GSIS impairment.

Associations between polycyclic aromatic hydrocarbons (PAHs) and respiratory diseases have been widely studied, but the effects of PAH on liver toxicity in adolescents are unclear. Here, 3194 adolescents with NHANES data from 2003 to 2016 were selected. PAH exposure was assessed by measuring PAH metabolites in urine. The outcome variables were the levels of alanine aminotransferase (ALT), aspartate amino transferase (AST) and gamma-glutamyl transpeptidase (GGT). The association between PAH exposure and liver function was evaluated by the weighted quantile sum (WQS) and logistic regression, and the associations between PAHs and inflammation and blood lipids were evaluated by linear regression. Covariates were adjusted for age, ethnicity, BMI, physical activity, family income, cotinine, and urinary creatinine. The results showed that for females, mixed PAH exposure was related to an increased ALT level (OR = 2.33, 95% CI 1.15, 4.72), and 2-fluorene contributed the most (38.6%). Urinary 2-fluorene was positively associated with an elevated ALT level (OR = 2.19 95% 1.12, 4.27, p for trend = 0.004). Mechanistically, 2-fluorene can cause a 3.56% increase in the white blood cell count, a 6.99% increase in the triglyceride level, and 1.70% increase in the total cholesterol level. PAHs may have toxic effects, possibly mediated by inflammation and blood lipids, on the adolescent female liver. Additional confirmatory studies are needed.

Copper-based (nano)pesticides in agroecosystems may result in unintended consequences on non-target soil microbial communities, due to their antimicrobial broad spectrum. We studied the impact of a commercial Cu(OH)₂-nanopesticide, over 90 days, at single and season agricultural application doses, in the presence and absence of an edaphic organism (the isopod Porcellionides pruinosus), on microbial communities’ function, structure and abundance. Results were compared to the effects of Cu(OH)₂-ionic. The nanopesticide application resulted in significant changes on both bacterial and fungal communities’ structure, particularly at the season application. The exposed bacterial community presented a significantly lower richness, and higher diversity and evenness while the exposed fungal community presented lower diversity and richness. At the functional level, a significant increase on microbial ability of carbon utilization and a significant decrease on the β−glucosidase activity was observed for communities exposed to the nanopesticide. Regarding Cu forms, less pronounced effects were observed in soils spiked with Cu(OH)₂-ionic, which might result from lower Cu concentration in porewater. The presence of P. pruinosus did not induce significant changes in diversity indexes (fungal community) and community-level physiological profiling, suggesting an attenuation of the nanopesticide effect. This study revealed that Cu(OH)₂-nanopesticide, at doses applied in agriculture, impact the soil microbial community, possibly affecting its ecological role. On the other hand, invertebrates may attenuate this effect, highlighting the importance of jointly including different interacting communities in the risk assessment of nanopesticides in soils.

Potentially toxic Cylindrospermopsis raciborskii blooms are of emerging concerns, as its scale is spreading from tropical regions to high latitudes, increasing the risk of aquatic biota being exposed to cylindrospermopsin (CYN). So far, CYN-producing C. raciborskii strains have only been reported in tropical waters which are commonly phosphorus (P)-deficient, where they can dominate phytoplankton communities. However, the influence of CYN on phytoplankton communities under different P status remains unclear. In this study, we first analyzed the summer observations of 120 tropical reservoirs in Guangdong Province. The proportion of potential CYN-producers was significantly higher in P-deficient and CYN-present reservoirs than that in P-sufficient or CYN-absent ones. This suggested that in P-deficient condition, the potential CYN producers might gain more advantages by the help of CYN. Then, in laboratory experiments we found that upon P deprivation, CYN did not inhibit the cell growth of other algal cells, but significantly stimulates them to secret more alkaline phosphatase (ALP) than in P-sufficient condition. Through transcriptomics, we further revealed that under such P-deficient condition, CYN remarkably induced intracellular nitrogen allocation and protein export system by activating the PIK3/Akt-cGMP/PKG signaling pathways in Scenedesmus bijugatus, thus enhancing its ALP secretion. Our study implies that CYN-induced ALP secretion is facilitated upon P deficiency, thus supporting the dominance of its producers C. raciborskii.

Since early 2020, the world has faced an unprecedented pandemic caused by the novel COVID-19 virus. In this study, we characterize the impact of the lockdown associated with the pandemic on air quality in six major cities across the state of Florida, namely: Jacksonville, Tallahassee, Gainesville, Orlando, Tampa, and Miami. Hourly measurements of PM₂.₅, ozone, NO₂, SO₂, and CO were provided by the US EPA at thirty sites operated by the Florida Department of Environmental Protection during mid-February to mid-April from 2015 through 2020. To analyze the effect of the pandemic, atmospheric pollutant concentrations in 2020 were compared to historic data at these cities during the same period from 2015 to 2019. Reductions in NO₂ and CO levels were observed across the state in most cities and were attributed to restrictions in mobility and the decrease in vehicle usage amid the lockdown. Likewise, decreases in O₃ concentrations were observed and were related to the prevailing NOₓ-limited regime during this time period. Changes in concentrations of SO₂ exhibited spatial variations, concentrations decreased in northern cities, however an increase was observed in central and southern cities, likely due to increased power generation at facilities primarily in the central and southern regions of the state. PM₂.₅ levels varied temporally during the study and were positively correlated with SO₂ concentrations during the lockdown. In March, reductions in PM₂.₅ levels were observed, however elevations in PM₂.₅ concentrations in April were attributed to long-range transport of pollutants rather than local emissions. This study provides further insight into the impacts of the COVID-19 pandemic on anthropogenic sources from vehicular emissions and power generation in Florida. This work has implications for policies and regulations of vehicular emissions as well as consequences on the use of sustainable energy sources in the state.

Bisphenol A and its alternatives are frequently detected in environmental and human samples, but studies associated with the pattern of combined health hazards from the exposure to the bisphenol mixtures are lacking, particularly for pregnant women. Here, we recruited 941 pregnant women with a full set of urine samples in the three trimesters collected under a cohort study project in Wuhan, China, between 2014 and 2015. We measured the concentrations of 8 bisphenols in 2823 urine samples, and calculated the average concentrations of bisphenols, which were detected in over 50% of samples, once during each trimester of pregnancy. We calculated the maximum cumulative ratio (MCR) on basis of estimated daily intake (EDI), hazard quotient (HQ), hazard index (HI) of three major bisphenols, including bisphenol A (BPA), bisphenol F (BPF), and bisphenol S (BPS), to find which one or mixtures drive risks. Participants were categorized into four groups according to their maximum HQ, HI and MCR values. We found negative relationships between log(MCR-1) and log(HI) with the slope (−0.6431). Percentage of HQ of BPA in HI ranged from 37.1% (<25th percentiles of HI) to 75.5% (>95th percentiles of HI) indicating the upward trend of dominance by BPA at increasing HI ranges. The cumulative health risks of bisphenol exposures largely originated from the health hazards of BPA and BPS, particularly BPA. The intervention for regulation on the production and application of BPA and its alternatives are urgent, and China should consider national regulation on these chemicals based on its risk to human health.