One-third of maize cultivation in Turkey has been performed in nutrient-rich soils of the coastal agricultural lands of the Black Sea Region, which is among the country's granaries. However, the yield of this chief crop is affected by Cu toxicity due to a decades-long abandoned opencast Cu-mine. As part of the modern agenda, against this problem, we valorized one of the region's signature plant waste by synthesizing a tea-derived biochar (BC) and evaluated for remediation effect on maize Cu tolerance. Among other rates (0%, 0.4%, 0.8%, 1.6%), maximum Cu absorption (168.27 mg kg⁻¹) was found in the 5%BC in in-vitro spiking experiments where natural Cu contamination levels were mimicked. Obvious increasing trends in both root and shoot tissues of maize plantlets growing in Cu-spiked soil (260.26 ± 5.19 mg Cu kg⁻¹) were recorded with proportionally increasing BC application rates. The black tea waste-BC (5%) amendment remarkably reduced the Cu uptake from Cu spiked-soil and showed no phenotypic retardation in maize. Accordingly, it boosted the metabolic and transcriptomic profile owing to up-regulation in the aquaporin and defense genes (PIP1;5 and POD1) by 1.31 and 1.6 fold. The tea-BC application also improved the soil-plant water relations by minimizing cytosolic volume changes between 85 and 90%, increasing chlorophyll intactness (65%) and membrane stability up to 41%. The tea-BC could be a strong agent with potential agronomic benefits in the remediation of the cationic Cu toxicity that occurred in the mining-contaminated agricultural soils.

Biofilm-mediated bioremediation of xenobiotic pollutants is an environmental friendly biological technique. In this study, 36 out of 55 bacterial isolates developed biofilms in glass test tubes containing salt-optimized broth plus 2% glycerol (SOBG). Scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and Congo red- and Calcofluor binding results showed biofilm matrices contain proteins, curli, nanocellulose-rich polysaccharides, nucleic acids, lipids, and peptidoglycans. Several functional groups including –OH, N–H, C–H, CO, COO⁻, –NH₂, PO, C–O, and C–C were also predicted. By sequencing, ten novel biofilm-producing bacteria (BPB) were identified, including Exiguobacterium indicum ES31G, Kurthia gibsonii ES43G, Kluyvera cryocrescens ES45G, Cedecea lapagei ES48G, Enterobacter wuhouensis ES49G, Aeromonas caviae ES50G, Lysinibacillus sphaericus ES51G, Acinetobacter haemolyticus ES52G, Enterobacter soli ES53G, and Comamonas aquatica ES54G. The Direct Red (DR) 28 (a carcinogenic and mutagenic dye used in dyeing and biomedical processes) decolorization process was optimized in selected bacterial isolates. Under optimum conditions (SOBG medium, 75 mg L⁻¹ dye, pH 7, 28 °C, microaerophilic condition and within 72 h of incubation), five of the bacteria tested could decolorize 97.8% ± 0.56–99.7% ± 0.45 of DR 28 dye. Azoreductase and laccase enzymes responsible for biodegradation were produced under the optimum condition. UV–Vis spectral analysis revealed that the azo (−NN−) bond peak at 476 nm had almost disappeared in all of the decolorized samples. FTIR data revealed that the foremost characteristic peaks had either partly or entirely vanished or were malformed or stretched. The chemical oxygen demand decreased by 83.3–91.3% in the decolorized samples, while plant probiotic bacterial growth was indistinguishable in the biodegraded metabolites and the original dye. Furthermore, seed germination (%) was higher in the biodegraded metabolites than the parent dye. Thus, examined BPB could provide potential solutions for the bioremediation of industrial dyes in wastewater.

Inland freshwater ecosystems are of increasing concerns in global methane (CH₄) budget in the atmosphere. Agricultural irrigation watersheds are a potential CH₄ emission hotspot owing to the anthropogenic carbon and nutrients loading. However, large-scale spatial variations of CH₄ concentrations and fluxes in agricultural catchments remain poorly understood, constraining an accurate regional estimate of CH₄ budgets. Here, we examined the spatiotemporal variations of dissolved CH₄ concentrations and fluxes from typical freshwater types (ditch, reservoir and river) within an agricultural irrigation watershed from Hongze catchment, which is subjected to intensive agricultural and rural activities in Eastern China. The dissolved CH₄ concentrations and fluxes showed similar temporal variations among the three freshwater types, with the highest rates in summer and the lowest rates in winter. The total CH₄ emission from this agricultural irrigation watershed was estimated to be 0.002 Gg CH₄ yr⁻¹, with annual mean CH₄ concentration and flux of 0.12 μmol L⁻¹ and 0.58 mg m⁻² d⁻¹, respectively. Diffusive CH₄ fluxes varied in samples taken from different freshwater types, the annual mean CH₄ fluxes for ditch, reservoir and river were 0.31 ± 0.06, 0.71 ± 0.13 and 0.72 ± 0.25 mg m⁻² d⁻¹, respectively. Among three freshwater types, the CH₄ fluxes were the lowest in ditch, which was associated with the lowest responses of CH₄ fluxes to water dissolved oxygen (DO), nitrate nitrogen (NO₃⁻-N) and sediment dissolved organic carbon (DOC) concentrations in ditch. In addition, water velocity and wind speed were significantly lower in ditch than in reservoir and river, suggesting that they also played important roles in explaining the spatial variability of dissolved CH₄ concentrations and fluxes. These results highlighted a need for more field measurements with wider spatial coverage and finer frequency, which would further improve the reliability of flux estimates for assessing the contribution of agricultural watersheds to the regional and global CH₄ budgets.

Hydrothermal carbonization is considered a powerful technology to convert sewage sludge (SS) into a valuable carbonaceous solid known as hydrochar (HC). Up to now criteria for landfill application of SS and HC are based only on physicochemical properties and levels of pollutant residues. Nevertheless, to ensure their safe environmental applications it is mandatory to develop biosensors which can provide relevant information on their toxic potential for natural ecosystems. Therefore, this study aimed to assess the suitability of a contact assay using zebrafish embryo/larvae combined with sub-lethal end-points to evaluate the hazard associated with SS and related HC exposure. A suite of biomarkers was also applied on larvae, related to detoxification and oxidative stress as the activity of Ethoxyresorufin-O-deethylase, glutathione-S-transferase, and catalase, the content of reactive oxygen species and the behavioral assay using the DanioVision™ chamber. Legacy priority pollutants were also measured either in SS and HC tested samples and in contact waters. The exposure to SS caused higher lethality compared to HC. No significant changes in the activity of oxidative stress markers was observed upon exposure to both matrices. The behavioral test showed a hypoactivity condition in larvae exposed to both SS and HC with the effects of SS stronger than HC. Chemical analysis revealed the presence of trace elements and halogenated compounds in either SS, HC. Heavy metals were also released in contact waters, while volatile hydrocarbons (C6–C10) and halogenated compounds resulted below LOD (<0.05 μ L⁻¹). Our study highlights the suitability of zebrafish embryotoxicity test, coupled with behavioral traits, as screening tool for assessing potential risks, associated with the landfill application of both SS and HC, for aquatic wildlife.

Atmospheric bioaerosols contain live and dead biological components that can enter the human respiratory tract (HRT) and affect human health. Here, the total microorganisms in a coastal megacity, Qingdao, were characterized on the basis of long-term observations from October 2013 to January 2021. Particular attention was given to the size dependence of inhalable bioaerosols in concentration and respiratory deposition in different populations on foggy and hazy days. Bioaerosol samples stained with 4,6-diamidino-2-phenylindole (DAPI) were selected to measure the total airborne microbe (TAM) concentrations with an epifluorescence microscope, while a multiple-path particle dosimetry model was employed to calculate respiratory deposition. The mean TAM concentrations in the particle size range of 0.65–1.1 μm (TAM₀.₆₅–₁.₁) were 1.23, 2.02, 1.60 and 2.33 times those on sunny reference days relative to the corresponding values on days with slight, mild, moderate and severe levels of haze, respectively. The mean concentration of TAMs in the particle size range of 0.65–2.1 μm (TAM₀.₆₅–₂.₁) on severely hazy days was (2.02 ± 3.28) × 10⁵ cells/m³, with a reduction of 4.16% relative to that on the reference days. The mean TAM₀.₆₅–₂.₁ concentration changed from (1.50 ± 1.37) × 10⁵ cells/m³ to (1.76 ± 1.36) × 10⁵ cells/m³, with TAM₀.₆₅–₁.₁ increasing from (7.91 ± 7.97) × 10⁴ cells/m³ to (1.76 ± 1.33) × 10⁵ cells/m³ on days with light fog days and medium fog, respectively. The modeling results showed that the majority of TAM₀.₆₅–₂.₁ deposition occurred in the extrathoracic (ET) region, followed by the alveolar (AL) region. When different populations were examined separately, the deposition doses (DDs) in adult females and in children ranked at the minimum value (6.19 × 10³ cells/h) and maximum value (1.08 × 10⁴ cells/h), respectively. However, the inhalation risks on polluted days, such as hazy, foggy and mixed hazy–foggy (HF) days, were still below the threshold for adverse impacts on human health.

Nanoplastics (NPs), the emerging contaminants in recent years, widely distributed in the environment and are bioaccumulated and biomagnified in organisms through food chain. A growing number of studies have detected plastic particulates in human placenta and blood. However, few studies have focused on their effects during human pregnancy. Herein, human trophoblast HTR-8/Svneo cells were used to evaluate the effects and the possible mechanism of 100-nm polystyrene NPs on placental trophoblasts at the maternal-fetal interface. The results showed that NPs entered the trophoblastic cytoplasm, decreased cell viability, caused cell cycle arrest, reduced the cell migration and invasion abilities, increased level of intracellular reactive oxygen species and the production of proinflammatory cytokines (TNF-α and IFN-γ) in a dose-dependent manner. Furthermore, global transcriptome sequencing (RNA-Seq) was performed on HTR-8/Svneo cells with or without 100 μg/mL PS-NP exposure for 24 h. A total of 344 differentially expressed genes were detected. The gene functions for regulation of leukocyte differentiation, response to stimulus, cell cycle, apoptotic process, and cell adhesion were enriched. Thyroid hormone, Hippo, TGF-β and FoxO signaling pathways were activated. Collectively, our data provided evidences for the adverse consequences of NPs on the biological functions of trophoblasts, which provided new insights into the potential trophoblast toxicity of NPs in mammals.

Marine sediments act as a sink for various heavy metals, which may have profound impact on sedimentary microbiota. However, our knowledge about the collaborative response of bacterial community to chronic heavy metal contamination remains little. In this study, concentrations of seven heavy metals (As, Cd, Cr, Cu, Hg, Pb, and Zn) in sediments collected from the East China Sea were analyzed and Illumina Miseq 16 S rRNA sequencing was applied to characterize the structure of bacterial community. Microbiota inhabiting sediments in the East China Sea polluted with heavy metals showed different community composition from relatively pristine sites. The response of bacterial community to heavy metal stress was further interrogated with weighted correlation network analysis (WGCNA). WGCNA revealed ten bacterial modules exhibiting distinct co-occurrence patterns and among them, five modules were related to heavy metal pollution. Three of them were positively correlated with an increase in at least one heavy metal concentration, hubs (more influential bacterial taxa) of which were previously reported to be involved in the geochemical cycling of heavy metals or possess tolerance to heavy metals, while another two modules showed opposite patterns. Our research suggested that ecological functional transition might have occurred in East China Sea sediments by shifts of community composition with sensitive modules majorly involved in the meaningful global biogeochemical cycling of carbon, sulfur, and nitrogen replaced by more tolerant groups of bacteria due to long-term exposure to low-concentration heavy metals. Hubs may serve as indicators of perturbations of benthic bacterial community caused by heavy metal pollution and support monitoring remediation of polluted sites in marine environments.

Wastewater treatment plants (WWTPs) are among the main hotspots of antibiotic resistance genes (ARGs) in the environment. Previously, we demonstrated that, by increasing anthropogenic pollution, the antibiotic resistome persisted in the microbial community of rivers and lakes, independently by changes in community composition. In this study, we reanalysed the data to test for the relation of metal resistance genes (MRGs), plasmids, and integrons to the persistence of the antibiotic resistome. The experiment consisted in replicated co-cultures of riverine or lacustrine microbial communities and WWTP effluents in different proportions. Samples before (T0) and after a short period of incubation (TF) were collected and community metagenomic data were obtained by shotgun sequencing. The data were processed to annotate MRGs, plasmids, and integrases. The integrases stabilized in the aquatic environment following the degree of contamination with effluent water (in particular in one site), whereas MRGs and plasmids showed stochastic trajectories. These results confirm the potential correlation between integrons and anthropogenic pollution, and the reliability of intI1 as a pollution marker. Only in one site MRGs, plasmids, and ARGs were correlated, highlighting their partial contribution to the persistence of ARGs in surface waters.

Microplastics (MPs) have been reported to threaten a wide variety of terrestrial, marine, and freshwater organisms. However, knowledge about the effects of MPs on anuran amphibians, one of the most threatened taxa worldwide, is still limited. To assess the effects of MPs on the growth and survival of the Italian agile frog (Rana latastei) and green toad (Bufotes balearicus), we exposed tadpoles to three different concentrations (1, 7, and 50 mg L⁻¹) of an environmental relevant mixture of microplastics (HPDE, PVC, PS and PES), recording data on their activity level, weight and mortality rates. While the effects of MPs on green toad tadpoles were negligible, Italian agile frog tadpoles were severely affected both in terms of growth and activity level, with high mortality rates even at the lowest MP density (1 mg L⁻¹). Our results suggest that MP contamination of freshwater habitats may contribute to the ongoing decline of anuran amphibians.

Accurate prediction of the colloid-driven transport of radionuclides in porous media is critical for the long-term safety assessment of radioactive waste disposal repository. However, the co-transport and corelease process of radionuclides with colloids have not been well documented, the intrinsic mechanisms for colloids-driven retention/transport of radionuclides are still pending for further discussion. Thus the controlling factors and governing mechanisms of co-transport and co-release behavior of Eu(III) with bentonite colloids (BC) were discussed and quantified by combining laboratory-scale column experiments, colloid filtration theory and advection dispersion equation model. The results showed that the role of colloids in facilitating or retarding the Eu(III) transport in porous media varied with cations concentration, pH, and humic acid (HA). The transport of Eu(III) was facilitated by the dispersed colloids under the low ionic strength and high pH conditions, while was impeded by the aggregated colloids cluster. The enhancement of Eu(III) transport was not monotonically risen with the increase of colloids concentration, the most optimized colloids concentration in facilitating Eu(III) transport was approximately 150 mg L⁻¹. HA showed significant promotion on both Eu(III) and colloid transport because of not only its strong Eu(III) complexion ability but also the increased dispersion of HA-coated colloid particles. The HA and BC displayed a synergistic effect on Eu(III) transport, the co-transport occurred by forming the ternary BC-HA-Eu(III) hybrid. The transport patterns could be simulated well with a two-site model that used the advection dispersion equation by reflecting the blocking effect. The retarded Eu(III) on the stationary phase was released and remobilized by the introduction of colloids, or by a transient reduction in cation concentration. The findings are essential for predicting the geological fate and the migration risk of radionuclides in the repository environment.