Fipronil is a broad-use insecticide with severe toxicity to fish. Biomarkers responses and bioaccumulation were evaluated on Prochilodus lineatus after exposure to environmentally relevant concentrations of fipronil (0.5 μg L⁻¹, 9 μg L⁻¹, and 100 μg L⁻¹) in a prolonged flow-through assay and ex vivo gills short-term exposition. Lipid peroxidation (LPO), oxidatively modified proteins (PO), the activity of superoxide dismutase (SOD), the content of reduced glutathione (GSH), antioxidant capacity against peroxyles (ACAP), and acetylcholinesterase (AChE) were evaluated. Besides, levels of fipronil and metabolites were analyzed by GC-ECD. At the end of the flow-through assay, fipronil, Fp. sulfone and Fp. desulfinyl were detected in fish, being liver the target organ. Fipronil prolonged exposition promoted oxidative damage in lipids and proteins, alterations in the defense system and low-antioxidant capacity in organs of P. lineatus. The brain AChE activity was affected after prolonged exposition. Ex vivo gills exposition to fipronil promoted changes in antioxidant capacity and damage to lipids, providing a fast and suitable test to assess the pesticide exposure in fish. The results revealed that fipronil at environmental concentrations would be an inducer of oxidative stress in this fish, becoming a vulnerable species to the effects of fipronil in aquatic environments.

Amphibians are the most important vulnerable non-target vertebrate group that are affected by pesticides. Most previous studies have confirmed the destructive effects of pesticides. But, so far, no comprehensive studies have been carried out in Iran. Therefore, to estimate the mortality rate of frogs during the growing season in different cultivating systems, we examined the presence of pesticides in water and substrate as indicators of habitat quality and in the liver tissue of Marsh frog Pelophylax ridibundus (Pallas, 1771), enclosed in the prepared cages at five rice paddy fields in Mazandaran province, Iran. The measurement of pollution was done using mass gas chromatography method and statistical analyses by Minitab software. Furthermore, the probable movement pattern of free frogs was analyzed using capture-mark-recapture method. Thirteen pesticides were detected both in the habitat and in frogs’ liver tissue. Among them ß-Mevinphos, Fenitrothion, Bromofos, and Trifluralin had the most frequent occurrence in liver tissue, and Diazinon with concentrations up to 517.8 μg/Kg had the highest concentration. Furthermore, there is a significant correlation (R² > 0.96) between water quality and frogs’ contamination, whereas, no correlation was observed between substrate pollution and frogs’ contamination. Pesticide concentrations were higher in two stations but lower than lethal doses to frogs, so that no mortality was observed at any of the stations. However, some specimens had a considerable muscle atrophy. Despite no significant movement pattern was detected, we can expect that if this trend continues, in a long term, they will face a reduction in the survival rate.

A dynamic kinetic model is presented for the UVC/H₂O₂-driven process. The model comprises 103 reactions, including background species, such as HCO₃–/CO₃²–, NO₂–, NO₃–, SO₄²⁻, Cl⁻, and H₂PO₄⁻/HPO₄²/PO₄³– anions, and effluent organic matter (EfOM) was validated based on experimental data obtained for the photooxidation of the nonribosomal peptide antibiotic zinc bacitracin (Zn-Bc, 34 μmol L⁻¹). The set of ordinary differential equations for 38 species was combined with the molar balances describing the recirculating tubular photoreactor used. Predictions for the photolytic and UVC/H₂O₂ processes confirmed the good agreement with experimental data, enabling the estimation of fundamental kinetic parameters, such as the direct photolysis quantum yield (Ф₂₅₄ ₙₘ, Zₙ₋Bc = 0.0143 mol Einstein⁻¹) and the second-order rate constants for the reactions of Zn-Bc with HO•, HO₂•, and O₂•⁻ radicals (2.64 × 10⁹, 1.63 × 10³, and 1.49 × 10⁴ L mol⁻¹ s⁻¹, respectively). The predicted optimum process conditions correspond to [H₂O₂]₀ = 6.8 mmol L⁻¹ and a specific photon emission rate of 11.1 × 10⁻⁶ Einstein L⁻¹ s⁻¹. Zn-Bc photooxidation was significantly impacted by wastewater constituents, particularly EfOM and HCO₃–/CO₃²– (i.e., alkalinity), resulting in a degradation rate about 32% lower compared to that obtained in deionized water. In particular, EfOM acts as a strong radical scavenger and inner filter. In addition, simulations pointed out the continuous tubular photochemical reactor as the best configuration for treating Zn-Bc-containing wastewater. This study hence provides a comprehensive modeling approach, especially useful for predicting the effect of complex water matrices on the performance of the UVC/H₂O₂ treatment process.

Sulfur-containing wastewater is very common as an industrial waste, yet a high-efficiency composite microbial agent for sulfur-containing wastewater treatment is still lacking. In this work, three novel and efficient desulfurizing bacteria were isolated from the sewage treatment tank of Zhejiang Satellite Energy Co., Ltd. They were identified as Brucella melitensis (S1), Ochrobactrum oryzae (S8), and Achromobacter xylosoxidans (S9). These three strains of bacteria were responsible for the oxidative metabolism of sodium sulfide via a similar polythionate pathway, which could be expressed as follows: S²⁻→S₂O₃²⁻/S⁰→SO₃²⁻→SO₄²⁻. Activated carbon, wheat bran, and diatomite at 1:1:1 ratio are used as carriers to construct a composite microbial agent containing the three bacteria. The desulfurization efficiency of 95% was predicted by response surface methodology under the following optimum conditions: the dosage of the inoculum was 3 g/L, pH 7.86, and temperature of 39 °C. Additionally, the impact resistance was studied in the anaerobic sequencing batch reactor. The removal capacity of microbial agent reached 98%. High-throughput analysis showed that composite microbial agent increased bacterial evenness and diversity, and the relative abundance of Brucellaceae increased from 5.04 to 8.79% in the reactor. In the process of industrial wastewater transformation, the transformation rate of sulfide by composite microbial agent was maintained between 70 and 81%. The composite microbial agent had potential for the treatment of sulfur-containing wastewater.

The studies related to air pollutants and their association with human health over the mountainous region are of utmost importance and are sparse especially over the Himalayan region of India. The linkages between various atmospheric variables and clinically validated data have been done using various datasets procured from satellite, model reanalysis, and surface observations during 2013–2017. Aerosol optical depth, air temperature, and wind speed are significantly related (p < 0.001) to the incidence of acute respiratory infections with its peak during winter. Model-derived particulate matter (PM₂.₅) shows high contributions of black carbon, organic carbon, and sulfate during winter. The wind roses show the passage of winds from the south–west and southern side of the region. Back trajectory density plot along with bivariate polar plot analyses have shown that most of the winds coming from the western side are taking a southward direction before reaching the study area and may be bringing pollutants from the Indo-Gangetic Plain and other surrounding regions. Our study shows that the accumulation of pollutants in the Himalayan valley is owing to the meteorological stability with significant local emissions from burning of biomass and biofuels along with long-range and mid-range transport during the winter season that significantly correlated with the incidence of acute respiratory infections in the region.

The organic integration of food security and agricultural mechanization has become a challenge to realize a low-carbon economy, which helps promote carbon peaking and carbon neutralization. In this work, a simultaneous equation model has developed to analyze the relationship between food security, agricultural automation, and agricultural carbon emissions in China. The ordinary least square method was used to verify the method. The logarithmic mean Divisia index decomposition was used to decompose further the influencing factors of agricultural carbon emissions. Results show that the organic coupling of a low-carbon economy, food security, and agricultural mechanization positively affects environmental protection. In which, unit fertilizer usage and crop sown area have the greatest impact on carbon emission intensity, followed by agricultural diesel fuel and agricultural plastic film. It is worth noting that the bottom line of the grain sown area cannot be touched. It is a prerequisite for ensuring grain production. Finally, this paper presents suggestions based on China’s achievements, where the top-level design is crucial.

Since conventional biological treatment methods are not sufficient alone to treat landfill leachate, this study investigated the efficacy of the heterogeneous Fenton process as a preliminary treatment technique. With this aim, a two-level factorial design combined with the response surface methodology (RSM) was used to optimize the operating parameters for the heterogeneous Fenton process used for treatment of leachate. The surface morphology and elemental analysis of Fe₃O₄ nanoparticles used in the heterogeneous Fenton process were completed with scanning electron microscope (SEM), energy dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FT-IR). In order to obtain maximum 75% chemical oxygen demand (COD) removal for treatment of leachate with the heterogeneous Fenton process, the optimum conditions for H₂O₂ and Fe₃O₄ dosages, stirring rate and initial pH parameters were 800 mg/L, 334.54 mg/L, 255 rpm and 3.34, respectively. The results obtained show the heterogeneous Fenton process abides by the second-order model (R² = 0.9896), and the variables mentioned above were confirmed to significantly affect the COD removal efficiency. Response surface graphs show the use of higher pH and chemical agents do not increase the COD removal efficiency. This study proves the applicability of the multi-response optimization program for treatment of leachate from a landfill site representing a serious problem in environmental terms.

The Dammam Formation in the southern and western deserts of Iraq is an important aquifer because it contains a huge groundwater reserve suitable for various uses. In the Karbala-Najaf plateau and the neighboring areas of the middle of Iraq, the drilling of groundwater wells usually fails due to the contamination of this aquifer with hydrocarbon from the deep oil reservoirs. This work suggests a method for the spatial delineation of groundwater contamination in this aquifer. Three machine learning classifiers, backpropagation multi-layer perceptron artificial neural networks (ANN), support vector machine with radial basis function (SVM-radial), and random forest (RF) with GIS, were used to map the probability of contamination in this aquifer. An inventory map of 139 groundwater boreholes (contaminated and non-contaminated) was utilized for building the models with seven factors that are considered to control contamination: fault density, distance to faults in general and the Abu Jir fault in particular, groundwater depth, hydraulic conductivity, aquifer saturated thickness, and land-surface elevation. The Relief-F feature selection method indicated that all factors were relevant. Five statistical measures were used for comparing the model performance: accuracy, sensitivity, specificity, kappa, and the area under the receiver operating characteristics curve (AUC). Applying the models using the R statistical package indicated that all models had excellent goodness-of-fit (accuracy > 90%), but the ANN (accuracy = 97%, sensitivity = 1.00%, specificity = 96%, kappa = 0.93, and AUC = 0.97) and RF (accuracy = 95%, sensitivity = 1.00%, specificity = 93%, kappa = 0.88, and AUC = 0.98) outperformed SVM-radial (accuracy = 92%, sensitivity = 1.00%, specificity = 90%, kappa = 0.82, and AUC = 0.95). The contamination probability values produced by these three models were categorized into different contamination zones range from very low to very high. The finding of this analysis may be used as a guide for drilling uncontaminated wells of groundwater.

Municipal solid waste (MSW) is regarded to be an important source of greenhouse gas emissions, which could result in a significant impact on climate change. This study conducted analyses of both cumulative energy demand (CED) and carbon footprint (CF) indicators per reference flow (RF) and identified the relationship between both the indicators, and additionally, it made some recommendations for MSW management strategies in Pyongyang, DPR Korea, based on life cycle thinking. This present study suggested using a hybrid CED indicator and the energy-related CF indicator for the analysis of the existing MSW management system, while applying system expansion for crediting the recycled materials, the energy recovery, and the compost/fertilizer. The result showed that the CED indicator in the MSW management system accounted for − 9,569.8 MJ/RF of primary energy savings in total, corresponding to the avoided emissions of − 1,522.89 kg CO₂eq/RF. The recycling and composting of waste presented energy savings due to the recycled materials and the avoided production of mineral fertilizers replaced with the compost, respectively. In addition, the incineration had some potential for energy recovery from waste, and it could result in crediting energy further, while the landfill should be improved in a more sustainable way of making use of the landfill gas and/or replacing the landfill with incineration with energy recovery. The results also indicated that the CED indicator was closely related to the CF indicator, valued as global warming potential, throughout the MSW management options/processes, and both the indicators could serve as an appropriate proxy of the environmental impacts on a life cycle phase.

Waste printed circuit boards (WPCBs) were co-pyrolyzed with iron oxides and iron salts. Solid, liquid, and gaseous products were collected and characterized. Co-pyrolysis with FeCl₂, FeCl₃, or FeSO₄ was able to increase the yield of liquid product which was rich in phenol and its homologues. Also, the addition of co-pyrolysis reagents reduced the release of brominated organics to liquid as Br was either fixed as FeBr₃ in solids or released as HBr. In particular, FeCl₂ showed the best ability to reduce the release of Br-containing organics to liquid compared with FeCl₃ and FeSO₄. Solid residuals were rich in iron oxides, glass fibers, and charred organics with surface areas of 20.6–26.5 m²/g. CO₂ together with a small amount of CH₄ and H₂ were detected in the gaseous products. Overall, co-pyrolysis could improve the quantity and quality of liquid oil which could be reused as chemical or energy sources. Pyrolysis of waste printed circuit board was promising as a method for recycling.