One possible way to reduce the environmental impacts of pesticides is by nanostructuring biocides in nanocarriers because this promotes high and localized biocidal activity and can avoid toxicity to non-target organisms. Neem oil (NO) is a natural pesticide with toxicity concerns to plants, fish, and other organisms. Thus, loading NO in a safe nanocarrier can contribute to minimizing its toxicity. For this study, we have characterized the integrity of a nanosilica-neem oil-based biocide delivery system (SiO₂NP#NO BDS) and evaluated its effectiveness in reducing NO toxicity by the Allium cepa test. NO, mainly consisted of unsaturated fatty acids, was well binded to the SiO₂NP with BTCA crosslinker. Overall, this material presented all of its pores filled with the NO with fatty acid groups at both the surface and bulk level of the nanoparticle. The thermal stability of NO was enhanced after synthesis, and the NO was released as zero-order model with a total of 20 days without burst release. The SiO₂NP#NO BDS was effective in reducing the individual toxicity of NO to the plant system. NO in single form inhibited the seed germination of A. cepa (EC₅₀ of 0.38 g L⁻¹), and the effect was no longer observed at the BDS condition. Contrarily to the literature, the tested NO did not present cyto- and geno-toxic effects in A. cepa, which may relate to the concentration level and composition.

Since the fifties, organochlorine pesticides (OCPs) had been used in agriculture to protect vegetables. Two decades after their ban by the Stockholm convention in 2001, OCPs are still present in agricultural soils inducing vegetable contamination with concentrations above Maximum Residue Level (MRL). This is a major concern for a 5 km² peri-urban vegetable growing valley located in the south west of France. In the present work, the sampling method was developed to clarify the spatial distribution of one OCP, Dieldrin, and its relationship with soil properties at the scale of study area. A total of 99 soil samples was collected for physicochemical analyses and Dieldrin concentrations. Results show Dieldrin concentrations in soils up to 204 μg kg⁻¹. The horizontal distribution of this pesticide is heterogeneous at the study area scale but homogeneous in each reference plot studied. About 85% of the contamination was located in the top soil layers (0–40 cm depth), but Dieldrin may still be quantified at a depth of 80 cm. Among all soil physicochemical parameters analysed, SOM was the most significantly related (P < 10⁻⁴) with Dieldrin concentrations, once different grain size fractions were considered. Moreover, results indicate a 33 times higher Dieldrin concentration and/or extractability for coarse sand than for other grain size fractions. These results show that the developed sampling method is adapted for the study area scale as it helps understanding the factors influencing the spatial distribution of Dieldrin. Historical amendments are the predominant factor for the horizontal contamination and deep ploughing for the vertical contamination. Also, the variations of coarse sand repartition in soils prevents identification of relationships between SOM and Dieldrin contamination in bulk soil. Further investigation is required to explain these relationships but these results highlight why no clear relationship between OCPs and SOM was previously identified.

Current approaches in chemical hazard assessment face significant challenges because they rely on live animal testing, which is time-consuming, expensive, and ethically questionable. These concerns serve as an impetus to develop new approach methodologies (NAMs) that do not rely on live animal tests. This study explored a molecular benchmark dose (BMD) approach using a 7-day embryo-larval fathead minnow (FHM) assay to derive transcriptomic points-of-departure (tPODs) to predict apical BMDs of fluoxetine (FLX), a highly prescribed and potent selective serotonin reuptake inhibitor frequently detected in surface waters. Fertilized FHM embryos were exposed to graded concentrations of FLX (confirmed at < LOD, 0.19, 0.74, 3.38, 10.2, 47.5 μg/L) for 32 days. Subsets of fish were subjected to omics and locomotor analyses at 7 days post-fertilization (dpf) and to histological and biometric measurements at 32 dpf. Enrichment analyses of transcriptomics and proteomics data revealed significant perturbations in gene sets associated with serotonergic and axonal functions. BMD analysis resulted in tPOD values of 0.56 μg/L (median of the 20 most sensitive gene-level BMDs), 5.0 μg/L (tenth percentile of all gene-level BMDs), 7.51 μg/L (mode of the first peak of all gene-level BMDs), and 5.66 μg/L (pathway-level BMD). These tPODs were protective of locomotor and reduced body weight effects (LOEC of 10.2 μg/L) observed in this study and were reflective of chronic apical BMDs of FLX reported in the literature. Furthermore, the distribution of gene-level BMDs followed a bimodal pattern, revealing disruption of sensitive neurotoxic pathways at low concentrations and metabolic pathway perturbations at higher concentrations. This is one of the first studies to derive protective tPODs for FLX using a short-term embryo assay at a life stage not considered to be a live animal under current legislations.

Wet deposition is a dominant removal pathway of carbonaceous particles from the atmosphere, but few studies have assessed the particulate carbon in precipitation in Chinese cities. To assess the characteristics and sources of particulate carbon, we measured the concentrations, fluxes, stable carbon isotopes, and radiocarbon of particulate carbon, and some cations concentrations in precipitation in Xi'an, China, in 2019. In contrast to rainfall samples, particulate carbon in snowfall samples in Xi'an showed extremely high concentrations and wet deposition fluxes. The concentrations as well as wet deposition fluxes showed no significant (p > 0.05) differences between urban and suburban sites, and they also exhibited low seasonality in rainfall samples. Water-insoluble organic carbon (WIOC) accounted for the majority (∼90%) of the concentrations and wet deposition fluxes of water-insoluble total carbon (WITC) in precipitation. The best estimates of source apportionment of WITC in precipitation showed that biological sources were the main contributor (80.0% ± 10.5%) in summer, and their contributions decreased to 47.3% ± 12.8% in winter. The contribution of vehicle exhaust emissions accounted for 11.7% ± 3.5% in summer and 39.0% ± 4.3% in winter, while the contributions of coal combustion were relatively small in summer (8.3% ± 7.0%) and winter (13.8% ± 8.5%). Biomass burning accounted for 25.7% ± 9.3% and 89.9% ± 0.7% of the biological sources in summer and winter, respectively, with the remainder comprising other sources of contemporary carbon. These results highlight the nonnegligible contributions of biogenic emissions and biomass burning to particulate carbon in precipitation in this city in summer and winter, respectively.

Understanding the metabolic defense and compensation to maintain homeostasis is crucial for assessing the potential health risk of organic pollutants in crops. Currently, limited understanding is available regarding the targeted metabolic pathways and response mechanism under contaminant stress. This study showed that ciprofloxacin (CIP) at the environmental concentrations (1, 5, 25, 50 mg/L) did not significantly inhibit growth or cause severe oxidative damage to rice (Oryza sativa L.). Instead, the increment in CIP concentration induced a series of sequential metabolic disorders, which were characterized predominantly by primary and secondary metabolic disturbances, including phenylpropanoid biosynthesis, the carbohydrate, lipid and amino acid metabolism. After CIP in vivo exceeded a certain threshold level (>0.29 mg/g dry weight), β-glucosidases (BGLUs) mediated the transition from the activation of the genes related to phenylpropanoid biosynthesis to the inhibition of the genes related to carbohydrate metabolism in rice. In particular, starch and sucrose metabolism showed the most profound perturbation stressed by environmental concentrations of CIP (5 mg/L) and other tested organic pollutants (10 μg/L of tricyclazole, thiamethoxam, polybrominated diphenyl ethers, and polychlorinated biphenyls). Besides, the key genes encoding endoglucanase and BGLU were significantly downregulated (|log₂FC| > 3.0) under 100 μg/L of other tested organic pollutants, supporting the transition from the activation of secondary defense metabolism to the disruption of primary energy metabolism. Thus, in addition to bioaccumulation, changes in BGLU activity and starch and sucrose metabolism can reflect the potential adverse effects of pollutants on rice. This study explained the stepwise metabolic and transcriptional responses of rice to organic pollutants, which provided a new reference for the comprehensive evaluation of their environmental risks.

As a common fungicide, tebuconazole are ubiquitous in the natural environment and poses many potential risks. In this study, we examined the effects of exposure to tebuconazole on colitis in mice and explored its underlying mechanism. Specifically, exposure to tebuconazole could cause structural damage and inflammatory cell infiltration in colon tissue, activate the expression of inflammation-related genes, disrupt the expression of barrier function-related genes, and induce the colonic inflammation in mice. Similarly, exposure to tebuconazole could also exacerbate DSS-induced colitis in mice. In addition, we found that tebuconazole also could change the composition of the gut microbiota. In particular, tebuconazole significantly increases the relative abundance of Akkermansia of mice. Moreover, tebuconazole resulted in metabolic profiles disorders of the serum, leading to significant changes in the relative contents of metabolites involving glycolipid metabolism and amino acid metabolism. Particularly, the results of the gut microbiota transplantation experiment showed that exposure to tebuconazole could induced colonic inflammation in mice in a gut microbiota–dependent manner. Taken together, these results indicated that tebuconazole could induce colitis in mice via regulating gut microbiota. Our findings strongly support the concept that the gut microbiota is a key trigger of inflammatory bowel disease caused by pesticide intake.

Nitrogen (N) and phosphorous (P) enrichment play an important role in regulating soil N₂O emission, but their interactive effect remains elusive (i.e. whether the effect of P or N enrichment on soil N₂O emission varies between ambient and elevated soil N or P conditions). Here, we conducted a Bayesian meta-analysis across the global natural ecosystems to determine this effect. Our results showed that P enrichment significantly decreased soil N₂O emission by 13.9% at ambient soil N condition. This N₂O mitigation is likely due to the decreased soil NO₃⁻-N content (−17.6%) derived by the enhanced plant uptake when the P limitation was alleviated by P enrichment. However, this P-induced N₂O (and NO₃⁻-N) mitigation was not found at elevated soil N condition. Additionally, N enrichment significantly increased soil N₂O emission by 101.4%, which was associated with the increased soil NH₄⁺-N (+41.0%) and NO₃⁻-N (+82.3%). However, the effect of N enrichment on soil N₂O emission did not differ between ambient and elevated soil P subgroups, indicating that the P-derived N₂O mitigation could be masked by N enrichment. Further analysis showed that manipulated N rate, soil texture, soil dissolved organic nitrogen, soil total nitrogen, soil organic carbon, soil pH, aboveground plant biomass, belowground plant biomass, and plant biomass nitrogen were the main factors affecting soil N₂O emission under N enrichment. Taken together, our study provides evidence that P enrichment has the potential to reduce soil N₂O emission from natural ecosystems, but this mitigation effect could be masked by N enrichment.

The real-time textile dyes wastewater contains hazardous and recalcitrant chemicals that are difficult to degrade by conventional methods. Such pollutants, when released without proper treatment into the environment, impact water quality and usage. Hence, the textile dye effluent is considered a severe environmental pollutant. It contains mixed contaminants like dyes, sodium bicarbonate, acetic acid. The physico-chemical treatment of these wastewaters produces a large amount of sludge and costly. Acceptance of technology by the industry mandates that it should be efficient, cost-effective and the treated water is safe for reuse. A sequential anaerobic-aerobic plant-microbe system with acclimatized microorganisms and vetiver plants, was evaluated at a pilot-scale on-site. At the end of the sequential process, decolorization and total aromatic amine (TAA) removal were 78.8% and 69.2% respectively. Analysis of the treated water at various stages using Fourier Transform Infrared (FTIR), High Performance Liquid Chromatography (HPLC)) Gas Chromatography-Mass Spectrometry (GC-MS) Liquid Chromatography-Mass Spectrometry (LC-MS) indicated that the dyes were decolourized and the aromatic amine intermediates formed were degraded to give aliphatic compounds. Scanning Electron Microscope (SEM) and Atomic Force Microscopy (AFM) analysis showed interaction of microbe with the roots of vetiver plants. Toxicity analysis with zebrafish indicated the removal of toxins and teratogens.

Predicting the toxicity of effluent exposures, which vary in duration, composition, and concentration, poses a challenge for ecological risk assessments. Effluent discharges may frequently result in the exposure of aquatic organisms to high concentrations of mixed contaminants for short durations. In the receiving environment effluents will undergo dilution and physical or chemical processes that further reduce contaminant concentrations at varying rates. To date, most studies comparing toxicity risks of continuous and pulsed contaminant exposures have focused on individual contaminants. In this study, the toxicity to the tropical euryhaline copepod Acartia sinjiensis of two complex effluents was assessed, comparing 6- and 18-h pulses and 78-h continuous exposures. Observations of larval development success and population size were completed after a 78-h incubation period, to observe for latent effects after pulse exposures. The chemical compositions of the effluents were assessed over time and different contaminants (i.e., metals, ammonia or organics) declined at differing rates. These were characterized as either a minimal, steady, or rapid decline. Nauplii development and population after 78 h were more impacted by effluent exposures following an 18-h pulse, compared to a 6-h pulse. Based on pulse-exposure concentrations, the 50% effect concentrations (EC50) were similar for continuous and 18-h exposures but up to 3-fold greater (lower toxicity) for the shorter 6-h exposures. Time-weighted average concentrations did not accurately predict toxicity from pulse exposures of the effluents. Concentration-addition toxicity modelling using toxicity data from pulse exposures of single contaminants was useful for predicting the toxicity of chemical mixtures exposed for varying durations. Recommendations for modified approaches to assessing risks of short-term effluent discharges are discussed.

Total suspended particulate (TSP) and PM₁₀ filters collected from two ambient air monitoring stations in Port Pirie were analysed to determine the impact of a lead (Pb) smelter redevelopment on air quality parameters including total elemental concentration, Pb isotopic ratio, Pb bioaccessibility and Pb speciation. Filters from 2009 to 2020 were analysed with a focus on samples from 2017 (immediately prior to smelter redevelopment) and 2020 (post-smelter redevelopment). Lead concentration in 2009–2020 TSP was variable ranging up to 6.94 μg m⁻³ (mean = 0.57 μg m⁻³), however, no significant decrease in Pb concentration was observed at either Port Pirie West (p = 0.56, n = 34) or Oliver Street (p = 0.32, n = 28) monitoring stations when 2017 and 2020 TSP values were compared. Similarly, no significant difference (p = 0.42) in PM₁₀ Pb concentration was observed in 2017 (mean = 0.80 μg m⁻³) and 2020 (0.60 μg m⁻³) Oliver Street filters. Although no change in percentage Pb bioaccessibility was observed when 2017 and 2020 Port Pirie West TSP samples were compared (mean of 88.7% versus 88.0%), Pb bioaccessibility was lower (p < 0.005) in both 2020 TSP (mean of 83.9% versus 62.9%) and PM₁₀ (mean of 70.8% versus 58.3%) Oliver Street filters compared to 2017. While scanning electron microscopy, energy dispersive x-ray spectroscopy identified a number of Pb phases within filters (galena, anglesite, cerussite, conglomerates), differences in Pb speciation between 2017 and 2020 filters could not be identified although it was presumed that this influenced Pb bioaccessibility outcomes at Oliver Street. Data from this study suggests that recent smelter redevelopments have not significantly decreased the concentrations of airborne Pb in Port Pirie although re-entrainment of soil-Pb from historical impact may also be a contributing Pb source.