Plant uptake is an important process in determining the transfer of pesticides through a food chain. Understanding how crops take up and translocate pesticides is critical in developing powerful models to predict pesticide accumulation in agricultural produce and potential human exposure. Herein, wheat was selected as a model plant species to investigate the uptake and distribution of eleven widely used pesticides in a hydroponic system as a function of time for 144 h. The time-dependent uptake kinetics of these pesticides were fitted with a first-order 1-compartment kinetic model. During 144 h, flusilazole and difenoconazole, with relative high log Kₒw (3.87 and 4.36, respectively), displayed higher root uptake rate constants (k). To clarify the role of root lipid content (fₗᵢₚ) in plant accumulation of pesticides, we conducted a lipid normalization meta-analysis using data from this and previous studies, and found that the fₗᵢₚ value was an important factor in predicting the root concentration factor (RCF) of pesticides. An improved correlation was observed between log RCF and log fₗᵢₚKₒw (R² = 0.748, N = 26, P < 0.001), compared with the correlation between log RCF and log Kₒw (R² = 0.686, N = 26, P < 0.001). Furthermore, the hydrophilic pesticides (e.g. log Kₒw < 2) were found to reach partition equilibrium faster than lipophilic pesticides (e.g. log Kₒw > 3) during the uptake process. The quasi-equilibrium factor (αₚₜ) was inversely related to log Kₒw (R² = 0.773, N = 11, P < 0.001) suggesting a hydrophobicity-regulated uptake equilibrium. Findings from this study could facilitate crop-uptake model optimization.

Discharged carbon nanotubes (CNTs) likely interact with co-existing organic contaminants (OCs) and pose joint toxicity to environmental microbes. Herein, hydrophobic pentachlorophenol (PCP) and hydrophilic ciprofloxacin (CIP) were used as representative OCs and their joint toxicities with CNTs to Bacillus subtilis were systematically investigated at cellular, biochemical, and omics levels. The 3-h bacterial growth half inhibitory concentrations of CNTs, PCP, and CIP were 12.5 ± 2.6, 3.5 ± 0.5, and 0.46 ± 0.03 mg/L, respectively, and they all could damage cell membrane, increase intracellular oxidative stress, and alter bacterial metabolomics and transcriptomics; while CNTs-PCP and CNTs-CIP binary exposures exhibited distinct additive and synergistic toxicities, respectively. CNTs increased bacterial bioaccumulation of PCP and CIP via destabilizing and damaging cell membrane. PCP reduced the bioaccumulation of CNTs, while CIP had no significant effect; this difference could be owing to the different effects of the two OCs on cell-surface hydrophobicity and CNTs electronegativity. The additive toxicity outcome upon CNTs-PCP co-exposure could be a result of the balance between the increased toxicity from increased PCP bioaccumulation and the decreased toxicity from decreased CNTs bioaccumulation. The increased bioaccumulation of CIP contributed to the synergistic toxicity upon CNTs-CIP co-exposure, as confirmed by the increased inhibition of topoisomerase Ⅳ activity and interference in gene expressions regulating ABC transporters and lysine biosynthesis. The findings provide novel insights into environmental risks of CNTs.

The surface modifications of nanoparticles (NPs), are well-recognized parameters that affect the toxicity, while there has no study on toxicity of Al₂O₃ NPs with different surface modification. Therefore, for the first time, this study pays attention to evaluating the toxicity and potential mechanism of pristine Al₂O₃ NPs (p-Al₂O₃), hydrophilic (w-Al₂O₃) and lipophilic (o-Al₂O₃) modifications of Al₂O₃ NPs both in vitro and in vivo. Applied concentrations of 10, 20, 40, 80,100 and 200 μg/mL for 24 h exposure on Caenorhabditis elegans (C. elegans), while 100 μg/mL of Al₂O₃ NPs significantly decreased the survival rate. Using multiple toxicological endpoints, we found that o-Al₂O₃ NPs (100 μg/mL) could induce more severe toxicity than p-Al₂O₃ and w-Al₂O₃ NPs. After uptake by C. elegans, o-Al₂O₃ NPs increased the intestinal permeability, easily swallow and further destroy the intestinal membrane cells. Besides, cytotoxicity evaluation revealed that o-Al₂O₃ NPs (100 μg/mL) are more toxic than p-Al₂O₃ and w-Al₂O₃. Once inside the cell, o-Al₂O₃ NPs could attack mitochondria and induce the over-production of reactive oxygen species (ROS), which destroy the intracellular redox balance and lead to apoptosis. Furthermore, the transcriptome sequencing and RT-qPCR data also demonstrated that the toxicity of o-Al₂O₃ NPs is highly related to the damage of cell membrane and the imbalance of intracellular redox. Generally, our study has offered a comprehensive sight to the adverse effects of different surface modifications of Al₂O₃ NPs on environmental organisms and the possible underlying mechanisms.

Nanoparticulate mineral UV filters, such as titanium dioxide (TiO₂) nanocomposites, are being increasingly used in sunscreens as an alternative to organic UV filters. However, there is still a lack of understanding regarding their fate and behavior in aquatic environments and potential environmental impacts after being released from a bather’s skin during recreational activities. In this work, we assessed the release, fate, and transformation of two commercial nanocomposite TiO₂ UV filters, one hydrophobic and one hydrophilic, in ultrapure water and simulated fresh- and seawater. The hydrophobic TiO₂ nanocomposite, T-SA, was coated with a primary Al₂O₃ photopassivation layer and a secondary stearic acid layer, while the hydrophilic TiO₂ nanocomposite, T-SiO₂, was coated with a single SiO₂ photopassivation layer. The influence of the sunscreen formulation was examined by dispersing the TiO₂ nanocomposites in their typical continuous phase (i.e., oil for T-SA and water for T-SiO₂) before introduction into the aqueous system. After 48 h of aqueous aging and 48 h of settling, 88–99% of the hydrophobic T-SA remained floating on top of the water column in all aqueous systems. On the other hand, 100% of the hydrophilic T-SiO₂ settled out of the water column in the fresh- and seawaters. With respect to the photopassivation coatings, no loss of the T-SA Al₂O₃ layer was detected after aqueous aging, but 99–100% dissolution of the SiO₂ layer on the T-SiO₂ nanocomposite was observed after 48 h in the fresh- and seawaters. This dissolution left behind T-SiO₂ by-products exhibiting a photocatalytic activity similar to that of bare rutile TiO₂. Overall, the results demonstrated that the TiO₂ surface coating and sunscreen formulation type drive environmental behavior and fate and that loss of the passivation layer can result in potentially harmful, photoactive by-products. These insights will help guide regulations and assist manufacturers in developing more environmentally safe sunscreens.

The importance of hydrochar properties for soil application is well known, but the effects of natural aging on hydrochar properties remain ambiguous. The present study aimed to determine the shift patterns in the physicochemical properties of hydrochar through a 16-month soil column aging experiment conducted in a rice-wheat rotation system with hydrochars derived from a wheat straw at 220 °C and 260 °C. Obvious decreasing hydrophilic/polarity indices and increasing porosity, ash content, and stability occurred in aged hyrdrochar, which were due to the dissolved organic matter (DOM) leaching and the interaction with mineral content and fertilizer during the 16-month aging process. Besides, fewer C–OH, slightly more CO, and higher aromaticity (C–C/CC) in aged hydrochar were observed. Meanwhile, the relative abundance of the compounds containing only C, H, and O atoms in water extract of aged hydrochar decreased, while that of the compounds containing C, H, O, and N atoms increased during aging; these findings were attributed to the less labile DOM and microbial degradation and the retention of some plant-derived dissolved organic carbon, respectively. This study provided 16-month aging characterization data regarding alteration in hydrochar physicochemical properties, which was conducive to make a better understanding of the use of hydrochars as sustainable soil amendments from agroecosystems and environmental perspective.

Effluent is often treated with ozone before being discharged into a natural water environment. This process will change the interaction between effluent organic matter and pollutants in aquatic environment. The impact of ozonation on complexation between dissolved organic matter in such wastewater and sulfadimidine often found in natural water was studied in laboratory experiments using four types of real wastewater. Ozonation was found to decrease the proportion of organic matter with a molecular weight greater than 5 kDa as well as protein-like, fulvic-like and humic-like components, but except the proportion of hydrophilic components. The aromaticity of the dissolved organic matter was also reduced after ozonation. The complexation of tryptophan and tyrosine with sulfadimidine mainly depends on their hydrophobicity and large molecular weight. Ozonation of fulvic and humic acid tends to produce small and medium molecular weight hydrophilics. The complexation of humic and fulvic acids with sulfadimidine was enhanced by ozonation. Dissolved organic matter, with or without oxidation, were found to weaken sulfadimidine’s inhibition of microbial growth, especially for Aeromonas and Acinetobacter species. This finding will expand our understanding about the impact of advanced treatment processes on the dissolved organic matters’ properties in effluent.

Transition metals (TMs) (e.g. copper (Cu) and iron (Fe)) and certain organic compounds are known active constituents causing oxidative potential (OP) by inhaled ambient fine particulate matter (PM₂.₅) in lung fluid. Humic-like substances (HULIS), isolated from atmospheric PM₂.₅, are largely metal-free and contain mixtures of organics that are capable of complexing TMs. TMs and HULIS co-exist in the water-extractable part of PM₂.₅. In this work, we used a solid phase extraction procedure to isolate the water-soluble TMs in the hydrophilic fraction (HPI) and HULIS in the hydrophobic fraction (HPO) and carried out this isolation procedure to a set of 32 real-world PM₂.₅ samples collected in Beijing and Hong Kong, China. We quantified two OP endpoints, namely hydroxyl radical formation (denoted as OP•OH) and ascorbic acid depletion (denoted as OPAA), by the two fractions separately and combined, as well as by the bulk water-soluble aerosols. OP•OH and OPAA were well-correlated in both separate fractions and their combined mixtures or bulk water-soluble aerosols. OP by HPI far exceeded that by HPO. On a per unit PM₂.₅ mass basis, the Hong Kong samples on average had a higher OPAA and OP•OH than the Beijing samples due to more water-soluble Cu. For HPI, Cu was a dominant OP•OH and OPAA contributor (>80%), although water-soluble Fe was present at a concentration approximately one order of magnitude higher. Suppression effects on OP•OH were observed through comparing the OP of the bulk water-soluble aerosol with that of HPI. Our work reveals the importance of monitoring PM₂.₅ chemical compositions (especially water-soluble redox active metals). Furthermore, we demonstrate the need to consider metal-organic interactions when evaluating the aggregate OP by PM₂.₅ from individual components or apportioning OP by PM₂.₅ to specific chemical components.

Polyvinyl chloride (PVC) is the third one after polyethylene and polypropylene in the production demand. It intends to grow further, causing an increase in the risk of health and ecological problems due to environmental accumulation and incineration. In the present study, we determined the biodegradative abilities of marine bacteria for PVC. Three potential marine bacterial isolates, T-1.3, BP-4.3 and S-237 (Vibrio, Altermonas and Cobetia, respectively) were identified after preliminary screening. They led to active biofilm formation, viability and protein formation on the PVC surface. The highest weight loss (1.76%) of PVC films was exhibited by BP-4.3 isolate after 60 days of incubation. Remineralization of PVC film was confirmed by CO₂ assimilation assay. Change in surface topography was confirmed by field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). The functional group peak intensity was decreased for the terminal chlorine group at the region 1000–1300 cm⁻¹, which indicated the dechlorination. Thermogravimetric, tensile strength and contact angle analysis showed a decline in the mechanical properties and a rise in PVC film's hydrophilic nature after biodegradation. These results demonstrated promising evidence of PVC degradation by marine bacteria.

Increasing human activities have caused the accumulation of dissolved organic nitrogen (DON) in the ocean, which can alter dominant coastal phytoplankton species. However, insights into DON's effects on marine phytoplankton growth are insufficient compared with those of dissolved inorganic nitrogen (DIN), especially regarding the role of specific DON components. Therefore, in this study, the effects of the hydrophilic (Hic) and low molecular weight (LMW) components of two anthropogenic DON sources on the growth and bioavailable nitrogen uptake of phytoplankton were studied using in situ cultural experiments conducted in Jiaozhou Bay, China. Animal-derived DON from domestic and livestock breeding showed a higher bioavailability compared with that of vegetal DON derived from agricultural sources, with bioavailable component proportions of 76% ± 4% and 66% ± 3%, respectively. Both forms of DON could be absorbed by Skeletonema costatum, stimulating it to become the dominant species in the mesocosm ecosystem; the hydrophilic components of DON contributed approximately 75% of the uptake of DON by S. costatum. The bioavailability of LMW DON was significantly (p < 0.05) lower than that of the Hic DON. The high bioavailability of the Hic DON was mainly associated with its protein-like T1 and T2 components, identified using parallel factor analysis on the excitation-emission-matrix spectra, while the low bioavailability of LMW DON was mainly associated with the humus-like A component. The protein-like T2 components may be directly absorbed by algae, while T1 may be transformed through mineralization and algal absorption. Understanding the impacts of anthropogenic DON and its components on phytoplankton will help improve coastal environmental management. More knowledge of the effect of anthropogenic DON on the phytoplankton community structure in coastal waters should be accumulated in the future.

This article provides an overview of the impacts of climate change stressors (temperature, ocean acidification, sea-level rise, and hypoxia) on estuarine and marine biota (algae, crustaceans, molluscs, corals, and fish). It also assessed possible/likely interactive impacts (combined impacts of climate change stressors and pollutants) on pollutants mobilization, pollutants toxicity (effects on growth, reproduction, mortality) and pollutants bioaccumulation in estuarine and marine biota. An increase in temperature and extreme events may enhance the release, degradation, transportation, and mobilization of both hydrophobic and hydrophilic pollutants in the estuarine and marine environments. Based on the available pollutants' toxicity trend data and information it reveals that the toxicity of several high-risk pollutants may increase with increasing levels of climate change stressors. It is likely that the interactive effects of climate change and pollutants may enhance the bioaccumulation of pollutants in seafood organisms. There is a paucity of literature relating to realistic interactive effects of climate change and pollutants. Therefore, future research should be directed towards the combined effects of climate change stressors and pollutants on estuarine and marine bota. A sustainable solution for pollution control caused by both greenhouse gas emissions (that cause climate change) and chemical pollutants would be required to safeguard the estuarine and marine biota.