Silver nanoparticles (AgNPs) of both biologically and chemically origins trigger various physiological and metabolic processes through interaction with plant cells, exerting positive, negative and inconsequential effects. However, their impacts on plant systems must be critically investigated to guarantee their safe application in food chain. In this study, the effects of chemically synthesized (synthetic) AgNPs (sAgNPs) and biologically synthesized (biogenic) AgNPs (bAgNPs) on physiological and biochemical features of Eschscholzia californica Cham were evaluated at different concentrations (0, 10, 25, 50 and 100 mg L⁻¹). Plants exposed to bAgNPs (at 10 and 25 mg L⁻¹) and sAgNPs (at 10 mg L⁻¹) displayed relatively uniform deposition of AgNPs on leaf surface, however, the higher concentration (100 mg L⁻¹) was accompanied by aggregation of AgNPs, resulting in anatomical and physiological disorders. Foliar application of both AgNPs at lower concentrations resulted in significant (P < 0.01) improve in the content of photosynthetic pigments (chlorophylls a, b, a+b, and carotenoids) and total phenolics over the control in a dose-related manner. Leaf relative water content decreased steadily with increasing both sAgNPs and bAgNPs concentrations-with sAgNPs being more inhibitive. Both types of AgNPs at 100 mg L⁻¹ significantly (P < 0.05) increased electrolyte leakage index, level of lipid peroxidation product (malondialdehyde), and leaf soluble sugar content when compared to controls. No significant difference was found on cell membrane stability index among the plants exposed to bAgNPs and sAgNPs at the lowest concentration over the control. Californidine content was significantly (P < 0.01, by 45.1%) increased upon all the bAgNPs treatments (with a peak at 25 mg L⁻¹) relative to control. The obtained extracts from plants treated with bAgNPs at lower concentrations revealed a significant induction of antioxidant capacity (based on DPPH˙ free radical scavenging and ferrous ions-chelating activities) with lower IC₅₀ values compared to the other treatments. Conclusively, bAgNPs at lower concentrations are potent elicitors of pharmaceutically active compounds biosynthesis, which enhance physiological efficiency of E. californica, but at higher concentrations bAgNPs are equally toxic as sAgNPs.

River floodplain ecosystems host one of the highest freshwater molluscan biodiversity on Earth. However, multiple human disturbances, such as loss of hydrological connectivity and deterioration of water quality, are seriously threatening most floodplain lakes throughout the world. Given the high imperilment rate of freshwater molluscs but the scarcity of studies examining the anthropogenic effects on this fauna, we test the response of mollusc assemblages to river-lake disconnection and eutrophication in 30 lakes in the Yangtze River floodplain, China. The species richness of entire Mollusca, Gastropoda and Bivalvia and 6 dominant families were all much lower at disconnected lakes than that in connected lakes, and decreased with increasing water eutrophication. The assemblage structure differed significantly among four lake groups for datasets based on entire Mollusca, Gastropoda and Bivalvia, indicating the serious impacts of hydrological disconnection and eutrophication. Moreover, the connected lakes showed significantly lower values of average taxonomic distinctness (Δ⁺) but higher values of variation in taxonomic distinctness (Λ⁺) than disconnected lakes. Such variations were triggered by the extirpation of congeneric and endemic species (mainly from families Unionidae and Viviparidae), which giving a waring of the loss of mollusc endemism in this region. In general, the present study showed that river-lake disconnection and deterioration of water quality resulted in serious biodiversity declines of both gastropods and bivalves in the Yangtze River floodplain lakes. A systematic approach including restoration of river-lake connectivity and habitats and improvement of water quality should be implemented in the conservation planning in this large river floodplain.

The adsorption of microplastic (MPs) on aquifer media is affected by their own properties and environmental factors. Research results have shown that the adsorption capacity of MPs on the three media has the following order: fine sand > medium sand > coarse sand, and the adsorption equilibrium times are 8 h, 12 h and 24 h, respectively. The adsorption process has three stages (fast linear distribution, slow adsorption and equilibrium stability), and the action law is compounded by the pseudo-second-order kinetic equation. After adsorption, MPs were observed on the three media, and there were single existence and aggregation phenomena. The energy spectrum analysis indicates that elemental carbon (C) appears on the surface of the medium after the action occurs, and the surface of the media adsorbs MPs to varying degrees. According to the results of infrared spectroscopy, after action, the peak areas of the absorption peaks at 680-880 cm⁻¹ and 1450-1620 cm⁻¹ increase. The absorption peaks are mainly C–H out-of-plane bending vibrations from aromatic hydrocarbons and C–H stretching vibrations on the benzene ring skeleton. As the initial concentration increases, the equilibrium adsorption capacity increases linearly. The isothermal adsorption of MPs in porous media conforms to the Freundlich model. The adsorption process is also affected by different anions and cations. The higher the ionic strength of NH₄⁺ is, the weaker the electrostatic effect of negatively charged MPs, thereby increasing the adsorption capacity of microplastics on porous media. Ca²⁺ can promote the adsorption of MPs by the media through the formation of ternary complexes between cations, MPs and surface functional groups. The increase in SO₄²⁻ and HCO₃⁻ concentrations gradually inhibits the adsorption of MPs.

The removal of antibiotics in subsurface flow constructed wetlands is performed through various removal mechanisms, such as adsorption, hydrolysis, microbial degradation and plant uptake. However, the contribution rates of the removal mechanisms in constructed wetlands are still not well studied. This study conducted a series of experiments and used multivariate statistical analysis to determine contribution rates for substrate adsorption, hydrolysis, and microbial degradation. Multiple stepwise regression analysis indicated that specific surface area and salt content were the main factors influencing sulfonamide adsorption, while temperature and pH were the main factors influencing sulfonamide hydrolysis. Variance partitioning analysis showed that the influence of physical-chemical factors was greater than that of nutrients on the microbial community. Partial least squares path analysis showed that the path coefficients of microbial degradation, adsorption and hydrolysis for sulfonamides removal in vertical subsurface flow constructed wetlands were 0.6339, 0.3608 and 0.0351, respectively, while the corresponding path coefficient were 0.5658, 0.4707 and 0.1079 in horizontal subsurface flow constructed wetlands, respectively. This means that microbial degradation contributes the most to the removal of sulfonamides in subsurface flow constructed wetlands. Enhanced microbial degradation may be a powerful measure to improve the removal of sulfonamides. These results will be helpful for understanding the removal mechanism of antibiotics and will provide a definite direction for pertinently improving sulfonamide removal efficiency in constructed wetlands.

The environmental risks of microplastics (MPs) have raised an increasing concern. However, the effects of MPs in anaerobic digestion (AD) systems of waste activated sludge (WAS), especially on the fate of antibiotic resistance genes (ARGs), have not been clearly understood. Herein, the variation and interaction of digestion performance, microbial communities and ARGs during AD process of WAS in the presence of polyethylene (PE) MPs with two sizes, PE MPs-180μm and PE MPs-1mm, were investigated. The results showed that the presence of PE MPs, especially PE MPs-1mm, led to the increased hydrolysis of soluble polysaccharides and proteins and the accumulation of volatile fatty acids. The methane production decreased by 6.1% and 13.8% in the presence of PE MPs-180μm and PE MPs-1mm, respectively. Together with this process, hydrolytic bacteria and acidogens were enriched, and methanogens participating in acetoclastic methanogenesis were reduced. Meanwhile, ARGs were enriched obviously by the presence of PE MPs, the abundances of which in PE MPs-180μm and PE MPs-1mm groups were 1.2–3.0 times and 1.5–4.0 times higher than that in the control by the end of AD. That was associated with different co-occurrence patterns between ARGs and bacterial taxa and the enrichment of ARG-hosting bacteria caused by the presence of PE MPs. Together these results suggested the adverse effects of PE MPs on performance and ARGs removal during AD process of WAS through inducing the changes of microbial populations.

Soil microorganisms represent one of the largest biodiversity reservoirs. However, most low-abundance, slow-growing or dormant microorganisms in soils are difficult to capture with traditional enrichment culture methods. These types of microorganisms represent a valuable “microbial seed bank”. To better exploit and utilize this “microbial dark matter”, we developed a novel strategy that integrates single-cell-level isolation with microfluidics technology and culture with resuscitation-promoting factor (Rpf) to isolate biphenyl-degrading bacteria from four typical soils (paddy soil, red soil, alluvial soil and black soil) in eastern China. Multitudinous bacteria were successfully isolated and cultured; some of the identified clades have not been previously linked to biphenyl biodegradation, such as Actinotalea, Curtobacterium and Rothia. Soil microcosmic experiments validated that some bacteria are responsible for biphenyl degradation in soil. In addition, genomic sequencing and Illumina MiSeq sequencing of 16S rRNA genes indicated that exogenous Rpf mainly promotes the recovery and growth of bacteria containing endogenous Rpf-encoding genes. In summary, this study provides a novel strategy for capturing target functional microorganisms in soils, indicates potential bioresources for the bioremediation of contaminated soils, and enhances our current understanding of the mechanisms involved in the response to exogenous Rpf.

In recent years, the application of green rusts (GRs) for water purification has received significant attention, but its full understanding has not been well achieved. Then, the comprehension about the synthesis and characteristics of GRs can highly favor their decontamination performances for the site-specific conditions. This review comprehensively summarized the synthesis, characteristics and performances of GRs including the GR (Cl⁻), GR (CO₃²⁻) and GR (SO₄²⁻) for sequestration of various aqueous pollutants (e.g., tetrachloride, Cr(VI), Se(VI), and U(VI), etc.). Generally, the different reactivity of GRs toward contaminants is strongly dependent on the GRs’ characteristics (e.g., interlayer distance, specific surface area, and Fe(II) content) and solution chemistry (e.g., pH, background electrolytes, dissolved oxygen, and contaminant concentration, etc.). In addition, the reaction mechanisms of GRs with the contaminants involve the redox reactions, adsorption, catalytic oxidation, interlayer and octahedral incorporation, which can mutually or singly contribute to the decontamination to varying degrees. Particularly, this review addressed the transformation pathways of GRs under various solution chemistry conditions and clarified that the stability of GRs should be the key challenge for the real application. Finally, how to effectively use the GRs for water decontamination was proposed, which will significantly benefit the rational control of environmental pollution.

Scientific literature is full of works studying the removal of different pollutants from water through different Advanced Oxidation Processes (AOPs). Many of them only suggest it is reused for agricultural purposes or for small crops in pots. This study is based on the reuse of reclaimed agricultural wastewater contaminated with four insecticides (chlorantraniliprole, imidacloprid, pirimicarb and thiamethoxam) for growing lettuce in field conditions. First, solar photocatalysis with TiO₂/Na₂S₂O₈ was used on a pilot plant in a sunny area (Murcia, SE of Spain) as an environmentally friendly technology to remove insecticide residues and their main reaction intermediates from contaminated water. The necessary fluence (H, kJ m⁻²) to accomplish 90% removal (H₉₀) ranged from 0.12 to 1212 kJ m⁻² for pirimicarb and chlorantraniliprole, respectively. Only six (derived from imidacloprid, pirimicarb and thiametoxam) of 18 transformation intermediate products studied were detected in reclaimed water during the photoperiod (2000 kJ m⁻² of accumulated UVA radiation) although all of them were totally photodegraded after a fluence of 1250 kJ m⁻². Secondly, reclaimed agro-wastewater was used to irrigate two lettuce crops grown under greenhouse conditions and under agricultural field conditions. In no cases, insecticide residues nor their TIPs were noticed above their respective LOQs (limits of quantification) in soil and lettuce samples (between 0.03 and 0.04 μg kg⁻¹ for pirimicarb and 2.49 and 2.23 μg kg⁻¹ for thiamethoxam, respectively) when they were irrigated with reclaimed water, while residues of the four insecticides and some of their intermediates were found in soil and lettuce by the end of cultivation when they were irrigated with non-reclaimed contaminated water. According to the results, this technology can be applied in a sustainable way, mainly in areas with water scarcity and high solar radiation, contributing to water utilisation in drought areas and the use of renewable energy.

Stable nitrogen isotope (δ¹⁵N) technology has often been used as a powerful tool to separate nitrogen oxides (NOₓ) produced by residential combustion (i.e., biomass burning and coal combustion) from other sources. However, the insufficient measurement of δ¹⁵N-NOₓ fingerprints of these emissions limits its application, especially in North China where residential emissions are significant. This study conducted combustion experiments to determine the δ¹⁵N-NOₓ of typical residential fuels in North China, including ten biomass fuels and five types of coal. The results showed that the δ¹⁵N of biomass varied between −6.9‰ and 2.3‰, which was lower than the δ¹⁵N of residential coal (−0.2‰–4.6‰). After combustion, the δ¹⁵N of biomass residues increased greatly, while that of coal residues showed no significant upward trend (p > 0.05). The δ¹⁵N-NOₓ produced by biomass burning ranged from −5.6‰ to 3.2‰ (−0.4‰ ± 2.4‰), showing a significant linear relation with δ¹⁵N-biomass. Comparatively, the δ¹⁵N-NOₓ derived from residential coal combustion was much higher (16.1‰ ± 3.3‰), ranging from 11.7‰ to 19.7‰. It was not well correlated with δ¹⁵N-coal, and only slightly lower than the estimated δ¹⁵N-NOₓ of industrial coal combustion (17.9‰, p > 0.05). These observations indicate that the δ¹⁵N-NOₓ of residential coal combustion is a result of the mixture of thermal- and fuel-released NOₓ. Based on the isotopic characteristics observed in this study, we analyzed the reported δ¹⁵N-NOₓ, and provided more statistically robust δ¹⁵N-NOₓ distributions for biomass burning (1.3‰ ± 4.3‰; n = 101) and coal combustion (17.9‰ ± 3.1‰; n = 26), which could provide guidance for scientific studies aiming to quantify the origin of NOₓ in North China and in other regions.

Endocrine disrupting chemicals (EDCs) are a matter of great concern. They are ubiquitous in the environment, are considered harmful to humans and wildlife, yet remain challenging to identify based on current international test guidelines and regulatory frameworks. For a compound to be identified as an EDC within the EU regulatory system, a plausible link between an endocrine mode-of-action and an adverse effect outcome in an intact organism must be established. This requires in-depth knowledge about molecular pathways regulating normal development and function in animals and humans in order to elucidate causes for disease. Although our knowledge about the role of the endocrine system in animal development and function is substantial, it remains challenging to predict endocrine-related disease outcomes in intact animals based on non-animal test data. A main reason for this is that our knowledge about mechanism-of-action are still lacking for essential causal components, coupled with the sizeable challenge of mimicking the complex multi-organ endocrine system by methodological reductionism. Herein, we highlight this challenge by drawing examples from male reproductive toxicity, which is an area that has been at the forefront of EDC research since its inception. We discuss the importance of increased focus on characterizing mechanism-of-action for EDC-induced adverse health effects. This is so we can design more robust and reliable testing strategies using non-animal test methods for predictive toxicology; both to improve chemical risk assessment in general, but also to allow for considerable reduction and replacement of animal experiments in chemicals testing of the 21st Century.