Water quality is essential for lake systems, which are not only influenced by climate change and human activities but are also controlled by high-frequency hydrological rhythms. However, the differences in water quality during different hydrological periods have not been addressed in detail. Here, a 15-year water quality dataset (2004–2018) was selected to explore the variation trends and their relationship with water level in different hydrological periods in Dongting Lake, a typical river-connected lake in China. The hydrological periods were classified into hydrological years and hydrological phases based on the characteristics of water level fluctuations. The results showed that annual variation in the water level in Dongting Lake fluctuated between 23.63 and 25.81 m from 2004 to 2018, and also displayed considerable water level differences ranging from 7.66 m (dry years) to 9.97 m (wet years) within a year. The water level of the lake phase showed significant differences among the different hydrological years. The concentration of TP, CODMₙ, and NH₃-N showed significant decreasing trends, whereas that of TN showed a significant increasing trend from 2004 to 2018. The TN concentration in wet years was significantly higher than that in dry years, which could be attributed to sewage discharge and hydrological conditions. The contributions of the lake phase to the total sewage discharge successively decreased from 64.54% in wet years to 59.47% in dry years, while the river phase showed the opposite trends, ranging from 35.46% to 40.53%, reflecting the strong relationship between water regimes and pollutant fluxes. A regression analysis indicated the different responses of water quality to water level fluctuations over hydrological years, and water quality in different hydrological phases clearly separated the lake and river phases, highlighting the influence of water level fluctuations on water quality within a year. To maintain the water quality of Dongting Lake, the control of external load should not be relaxed, and hydrological regulation should be actively carried out within each year.

Polyethylene (PE) and polypropylene (PP) microplastics (MPs), as carriers, can bind with pesticides, which propose harmful impacts to aqueous ecosystems. Meanwhile, carbofuran and carbendazim (CBD), two widely used carbamate pesticides, are toxic to humans because of the inhibition of acetylcholinesterase activity. The interaction between two MPs and two pesticides could start in farmland and be maintained during transportation to the ocean. Herein, the adsorption behavior and mechanism of carbofuran and carbendazim (CBD) by PE and PP MPs were investigated via characterization and density functional theory (DFT) simulation. The adsorption kinetic and thermodynamic data were best described by pseudo-second-order kinetics and the Freundlich models. The adsorption behaviors of individual carbofuran/CBD on both MPs were very similar. The CBD adsorption rate and capacity of PE and PP MPs were higher than those of carbofuran. This phenomenon explained the lower negative effects of DOM (oxalic acid, glycine (Gly)) on CBD adsorption relative to those of carbofuran. The presence of oxalic acid and Gly decreased the PE adsorption by 20.40–48.02% and the PP adsorption by 19.27–42.11%, respectively. It indicated the significance of DOM in carbofuran cycling. The adsorption capacities were negatively correlated with MPs size, indicating the importance of specific surficial area. Fourier transformation infrared spectroscopy before and after adsorption suggested that the adsorption process did not produce any new covalent bond. Instead, intermolecular van der Waals forces were one of the primary adsorption mechanisms of carbofuran and CBD by MPs, as evidenced by DFT calculations. Based on the zeta potential, the electrostatic interaction explained the higher adsorption CBD by MPs than carbofuran.

In this work, we prepared nanocomposites of nickel-decorated manganese oxynitride on graphene nanosheets and demonstrated them as photocatalysts for degradation of acetylsalicylic acid (ASA). The catalyst exhibited a high degradation efficiency over ASA under visible light irradiation and an excellent structural stability after multiple uses. Compared to manganese oxide (MnO) and manganese oxynitride (MnON) nanoparticles, larger specific surface area and smaller band gap were observed for the nanocomposite accounting for the enhanced photocatalytic efficiency. Besides the compositional effect of the catalyst, we also examined the influence of various experimental parameters on the degradation of ASA such as initial concentration, catalyst dose, initial pH and additives. The best performance was obtained for the nanocomposite when the catalyst dose was 10 mg/mL and the initial pH 3. Detection of intermediates during photocatalysis showed that ASA undergoes hydroxylation, demethylation, aromatization, ring opening, and finally complete mineralization into CO₂ and H₂O by reactive species. For practical applications as a photocatalyst, cytotoxicity of the nanocomposite was also evaluated, which revealed its insignificant impact on the cell viability. These results suggest the nanocomposite of nickel-decorated manganese oxynitride on graphene nanosheets as a promising photocatalyst for the remediation of ASA-contaminated water.

Anaerobic digestion (AD) with thermal hydrolysis pre-treatment (THP) is an effective sludge treatment method which provides several advantages such as enhanced biogas formation and fertilizer production. The main limitation to THP-AD is that hazardous odors, including NH₃ and volatile sulfur compounds (VSCs), are emitted during the sludge treatment process. In order to develop strategies to eliminate odors, it is necessary to identify the key odors and emissions sites. This study identified production of NH₃ (741.60 g·dry sludge t⁻¹) and VSCs (277.27 g·dry sludge t⁻¹) during sludge AD after THP, and measured emissions in each of the THP-AD sludge treatment sites. Odor intensity, odor active values, permissible concentration-time weighted average, and non-carcinogenic risks were also assessed in order to determine the sensory impact, odor contribution, and health impacts of NH₃ and VSCs. The results revealed that odor pollution existed in all of the test sites, particularly in the sludge pump room and pre-dehydration workshop. NH₃, H₂S, and methyl mercaptan caused very strong odors, and levels of NH₃ and H₂S were enough to impact the health of on-site employees.

This is a research comment on the ochratoxin A (OTA) degradation mechanism by Lysobacter sp. CW239 regarding the previous publication in Environmental Pollution (Wei et al., 2020). Three possible degradation mechanisms were discussed in the referred publication, but without definite evidences, it was not clear which one worked actually. Here, the gene cp4 deficient mutant CW239Δᶜᵖ⁴ was successfully constructed, and the carboxypeptidase CP4 role on OTA degradation in strain CW239 was validated in vivo. As a result, the mutant CW239Δᶜᵖ⁴ without gene cp4 showed less than 10% reduction of 24 hrs degradation ratio compared to wide-type strain CW239. After the gene cp4 complemented to CW239Δᶜᵖ⁴, the complementary strain (+)cp4 recovered the degradation ability to wide-type. The validation result indicated that the third degradation mechanism (i.e., OTA is degraded by joint action of multiple enzymes in CW239) proposed previous (Wei et al., 2020) was correct route for the degradation strain. This commentary was significant to the following studies on the pollutant detoxify strains with similar degradation characters between identified enzyme and the host strain.

Various chemicals containing pesticides can induce adipogenesis and cause obesity. Organophosphorus pesticides have been used for pest control. Here, we investigated the estrogen receptor (ER)-dependent adipogenesis-inducing effect of representative organophosphorus pesticides (OPs), diazinon, phoxim, terbufos and tolclofos-methyl in 3T3-L1 adipocytes. Four OPs exhibited ER agonistic effect, determined using the OECD Performance Based Test Guideline No. 455; in vitro ER stably transfected transactivation assay using ERα-HeLa-9903 cell line, through binding affinity to ERα. Additionally, they increased lipid droplet accumulation in a dose-dependent manner, which was suppressed by ICI182,780, a well-known ER antagonist. Four OPs treatment induced peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), and perilipin expression. Furthermore, PPARγ, C/EBPα and perilipin expression was inhibited by co-treatment with ICI182,780. The increased mRNA expression of lipoprotein lipase and fatty acid synthase by four OPs was suppressed by co-treatment with ICI182,780. These results indicated that diazinon, phoxim, terbufos, and tolclofos-methyl might have adipogenesis-inducing effect mediated by interacting with ER.

With the exploitation of lead-zinc deposits, lead content around mining areas has seriously exceeded the recommended level. The most challenging problem is how to reduce lead contamination in soil efficiently. In this study, we developed a method to remediate lead-contaminated soil by adding Morchella mycelium. First, we compared the repair effects of mycelium and hyperaccumulator by conducting pot experiments. Then, we investigated the mechanism through which mycelium repairs lead-contaminated soil by conducting simulation experiments. Results showed that using mycelium was a more efficient way to repair soil than using hyperaccumulator. Compared with the untreated group, mycelium reduced the lead content of crops by 34.83 % and raised dry biomass by 134.05 % when lead addition was 800 mg/kg. After mycelium fixation, soil catalase, urease, cellulase, and sucrase activities were significantly enhanced, and the bioavailability of lead decreased significantly. The lead solution exposure simulation test showed that Morchella mycelium immobilized lead due to its extracellular secretions. That is, mycelium secreted metabolites and lead to form salt crystals, reducing bioavailable lead content. In addition, Morchella mycelium restoration may effectively improve soil fertility and increase crop yields. Thus, mycelium may be used successfully in alternative green repair methods for environmental heavy metal remediation.

Development of efficient, green and low-cost natural mineral-based reductive materials is promising to remediation of hexavalent chromium(Cr(VI))-contaminated soil. Considering the synergetic effect between pyrite and zerovalent iron (ZVI), an activated pyrite supported ZVI(ZVI/FeS₂) with high reducing activity was developed by ball milling activation of natural pyrite and sulfidation of ZVI. The remediation property of ZVI/FeS₂ for Cr(VI)-contaminated soil was evaluated with different ZVI/FeS₂ dosage, soil-water ratio, initial pH, time and temperature, as well as the stability of Cr. The results showed that ZVI/FeS₂ possessed high reduction activity with soil Cr(VI) removal rate up to 99 % even under alkaline condition, and soil with different pH values eventually converged to neutral after 90 days, indicating that ZVI/FeS₂ has a good self-regulating alkaline ability. The reduction process conformed to Langmuir-Hinshelwood first-order kinetics and was a spontaneous and endothermic process. The lower activation energy of 17.97 kJ mol⁻¹ (usually 60–250 kJ mol⁻¹) indicated that the reduction reaction of Cr(VI) was particularly easy to occur. The speciation change of Cr in soil within 30 days demonstrated that the Cr in the soil was converted from a readily migratable state to a more stable state, where the Fe–Mn oxide bound fraction reached 85.03 % due to the generation of Cr(III)/Fe(III) co-precipitation. The results of long-term stability experiments showed that the leaching concentrations of Cr(VI) and total Cr decreased significantly after the ZVI/FeS₂ treatment and remained stable at very low levels for 180 days. This study provided a sustainable way to fully utilize natural pyrite minerals to obtain iron-bearing reductive materials for feasible, effective and long-term stable immobilization of Cr(VI) in soil.

Chlorinated polyfluoroalkyl ether sulfonates (Cl-PFESAs), are ubiquitous alternatives to perfluorooctane sulfonate (PFOS), a widely used poly- and perfluoroalkyl substance (PFAS). Despite in vivo and in vitro evidence of metabolic toxicity, no study has explored associations of Cl-PFESAs concentrations with metabolic syndrome (MetS) in a human population. To help address this data gap, we quantified 32 PFAS, including 2 PFOS alternative Cl-PFESAs (6:2 and 8:2 Cl-PFESAs) in serum from 1228 adults participating in the cross-sectional Isomers of C8 Health Project in China study. The odds ratios (ORs) and 95% confidence intervals (CIs) of MetS and its various components were estimated using individual PFAS as a continuous or categorical predictor in multivariate regression models. The association between the overall mixture of PFAS and MetS was examined using probit Bayesian Kernel Machine Regression (BKMR-P). Greater serum PFAS concentrations were associated with higher odds of MetS and demonstrated a statistically significant dose-response trend (P for trend < 0.001). For example, each ln-unit (ng/mL) increase in serum 6:2 Cl-PFESA was associated with a higher prevalence of MetS (OR = 1.52, 95% CI: 1.25, 1.85). MetS was also 2.26 (95% CI: 1.59, 3.23) times more common in the highest quartile of serum 6:2 Cl-PFESA concentration than the lowest, and particularly high among women (OR = 6.41, 95% CI: 3.65, 11.24). The BKMR-P analysis showed a positive association between the overall mixture of measured PFAS and the odds of MetS, but was only limited to women. While our results suggest that exposure to Cl-PFESAs was associated with MetS, additional longitudinal studies are needed to more definitively address the potential health concerns of these PFOS alternatives.

The main objective of the Marine Strategy Framework Directive (MSFD) was to achieve a Good Environmental Status (GES) in European waters by 2020, according to 11 descriptors. Descriptor 10 is related to marine litter and envisages that the properties and quantities of marine litter are at a level that does not cause harm to the coastal and marine environment. Even if GES was not achieved by 2020, the first MSFD implementation cycle filled many gaps in knowledge. Here we present the first data (2015–2018) on beach litter densities along Italian coasts and discuss lessons learnt and future perspectives. The beach litter median density was 477 items/100 m (interquartile range: 261–934 items/100 m), but subregional differences emerged both in terms of litter quantities and composition. The Adriatic Sea was the most polluted subregion (590 items/100 m), followed by the Western Mediterranean Sea (491 items/100 m) and the Ionian Sea and Central Mediterranean Sea subregion (274 items/100 m). A high presence of aquaculture-related litter (mainly mussel nets) characterised beaches in the Adriatic Sea. At the same time, the numbers of cotton bud sticks were extremely high in some beaches of the Western Mediterranean Sea. General litter (items discarded or left by the public on the coast or inland and carried by winds and rivers or objects originating from tourism and recreation at land or sea, poor waste management practices, etc.) was the most common litter typology (38.8%). The results of this study represent the first baseline to compare achievement towards GES in the next years and the efficacy of the program of measures which entered into force in 2016, concerning beach litter densities and composition. They also highlight the necessity of a joint effort for deploying harmonised marine litter monitoring methodologies across the European Member States to obtain comparable results.