This study investigated the feasibility and mechanism of sulfide-modified nanoscale zero-valent iron supported on biochar (S-nZVI@BC) for the removal of TCE in the scenario of groundwater remediation. The effects of some critical factors, including pyrolysis temperature of biochar, mass ratio of S-nZVI to BC, initial pH, typical groundwater compositions, co-contaminants, and particle aging time, on the TCE removal were examined. The results revealed that the different pyrolysis temperatures could change physicochemical properties of BC, which influenced the TCE adsorption and degradation by S-nZVI@BC. The mass ratio of S-nZVI to BC could determine the extent of adsorption and degradation of TCE. The total removal of TCE was not significantly influenced by the initial pH (3.0–9.0), but the degradation of TCE was enhanced at higher pH. Notably, the typical anions (SO₄²⁻, HCO₃⁻, and HPO₄²⁻), humic acid, and co-contaminants (Cr(VI) and NO₃⁻) in groundwater all slightly influenced the total removal of TCE, but markedly inhibited its degradation. Additionally, after exposure to air over different times (5 days, 10 days, 20 days, and 30 days), the reactivity of S-nZVI@BC composites was apparently decreased due to surface passivation. Nevertheless, the aged S-nZVI@BC composites still maintained relative high removal and degradation of TCE when the reaction time prolonged. Overall, the results showed that the S-nZVI@BC, combining the high adsorption capacity of BC and the high reductive capacity of S-nZVI, had a much better performance than the single S-nZVI or BC, suggesting that S-nZVI@BC is one promising material for the remediation of TCE-contaminated groundwater.

Sulfamethoxazole (SMX), a representative sulfonamide antibiotic, has been identified as a new kind of persistent pollutant with property of hard biodegradation and hydrolyzation. Conventional methods cannot remove it well. In this study, the performances and mechanisms for SMX degradation were examined by persulfate (PS) activation with nanoscale zero-valent iron (nZVI) at various conditions including dosages of nZVI and PS, pH value, and initial SMX concentration. Results showed that about 88.4% SMX (10 mg/L) was removed by nZVI/PS system (0.10 g/L nZVI, 1.0 mM PS) within 120 min compared to 63.1% by nZVI alone system under room temperature. Lower initial SMX concentration and higher PS concentration were beneficial to the degradation of SMX, while pH (from 3.11 to 9.33) and nZVI dosage (from 0.05 to 0.30 g/L) had little effect. Radical quenching experiment and electron spin resonance test demonstrated that the degradation of SMX was attributed to sulfate radicals (SO₄·⁻) and hydroxyl radicals (·OH) produced in this system. SMX reduction reaction by nZVI in nZVI/PS process was proved by reductive-oxidative degradation experiment and HPLC test, and the reduction product could be oxidized by SO₄·⁻ and ∙OH to other products even to H₂O and CO₂. Further, probable removal mechanisms have also been proposed. This study manifests that nZVI/PS system is effective for SMX removal and may provide some ideas for understanding the transformation process of antibiotic in iron-based advanced oxidation processes.

Biochar has been widely accepted as a soil amendment to improve nitrogen (N) use efficiency, but the effect of biochar on N transformation metabolic pathways is unclear. A field experiment was conducted to evaluate the effect of biochar on N transformation in drip-irrigated cotton field. Four treatments were set as (1) no N fertilization (CK), (2) N fertilizer application at 300 kg ha⁻¹ (N300), (3) N fertilizer application plus cotton straw (N300+ST), and (4) N fertilizer application plus cotton straw–derived biochar (N300+BC). Result showed that soil total N in N300+ST and N300+BC was 16.3% and 24.9% higher than that in N300, respectively. Compared with N300+ST, the nitrate N (NO₃⁻-N) in N300+BC was significantly increased. Acidolyzable N and non-acidolyzable N in N300+ST and N300+BC were higher than those in CK and N300, while N300+BC performed better than N300+ST. Furthermore, the N fertilizer use efficiency of cotton in N300+ST and N300+BC was 15.1% and 23.2% higher than that in N300, respectively. Both N fertilizer incorporations with straw and biochar significantly altered the microbial community structures and N metabolic pathways. Genes related to denitrification and nitrate reduction in N300+ST were higher than those in N300, and N300+BC significantly increased nitrification and glutamate synthesis genes. Therefore, N fertilizer application plus cotton straw–derived biochar changed the microbial community composition, increased nitrification and glutamate synthesis enzyme genes which were beneficial to the accumulation of soil N content, and improved soil N retention capacity thus to increase N fertilizer use efficiency.

In the developing world, rapid urbanization and industrialization produces an enormous volume of wastes daily. This study was aimed to explore the potential and risks associated with sewage sludge through the characterization and fractionation technique. Sewage sludge samples were collected from various wastewater treatment in five different cities of Pakistan. Considerable amounts of macro-elements were detected in all types of sewage sludge samples. The pHw of all sewage sludge were neutral to slightly alkaline in reaction. Total organic carbon (TOC) was maximum (18.73%) with Coca-Cola sewage sludge (CSS) while the minimum (14.69%) was with Water and Sanitation Agency (WASA) sewage sludge (WSS). Percent relative distribution of cadmium (Cd) was higher in residual fraction (F4) up to 52% in the Nestle wastewater treatment plant, Sheikhupura (NSS). The chromium (Cr) concentration in Kasur sewage sludge (KSS) was extremely in mobile fraction (exchangeable) as compared with all other sludge samples, therefore showing a higher level of risk assessment code. While in the case of Iron (Fe), mobility was less and its maximum portion was noted in residual fraction (F4) of all sewage sludge samples. Percent distribution of manganese (Mn) showed variable trends for different sewage sludge samples. Zinc (Zn) concentration showed high mobility (exchangeable fraction) in case of NUST wastewater treatment plant, Islamabad (NTS) (31.16%) and WSS (37.83%) as compared with other sewage sludges. The risk assessment code indicated that Zn and Ni had a medium level of risk with I-9 Sector wastewater treatment plant, Islamabad (ISS), CSS, KSS, and NSS whereas these pose a high risk with NTS and WSS. Based on physicochemical properties, nutrients, trace elements, mobility, and risk assessment code, it was concluded that KSS should not be recommended at any application rate while NTS and WSS may be used at low application rates whereas ISS, CSS, and NSS may be used for agricultural crop production.

The impact of soil lead (Pb) pollution on survival, growth, and reproduction of the collembolan, Folsomia candida, and Pb compartmentation in its gut and remaining body parts were studied by exposing animals to laboratory-spiked soil. The survival, growth, and reproduction of F. candida were significantly reduced by increasing soil Pb concentration. The LC₅₀ values of survival based on total and CaCl₂-extractable Pb concentration in soil were 2562 mg kg⁻¹ and 351 mg kg⁻¹, respectively. The EC₅₀ values of reproduction were 1244 mg kg⁻¹ and 48 mg kg⁻¹, respectively. The Pb concentration in whole body, gut, and remaining body parts was significantly increased with the increase of soil Pb concentration and followed an exponential increase when the soil Pb concentration was equal to or above a threshold (1000 mg kg⁻¹ for whole body and remaining body part, 500 mg kg⁻¹ for gut). Below this threshold, these relationships were linear. The Pb concentration in the gut was higher than whole body and remaining body part of F. candida, and the threshold of internal Pb concentration at which F. candida can compensate was in the range 7–13 mg Pb kg⁻¹ dry animal (corresponding to soil Pb concentration 500–1000 mg Pb kg⁻¹ dry soil). The results indicate that reproduction of F. candida was a more sensitive indicator of lead toxicity than survival and growth. Pb was mainly accumulated in the gut of F. candida. We discuss the internal Pb concentration as an indicator of adverse effects in the risk assessment of soil Pb pollution.

Carps belonging to species Cyprinus carpio (carp) were fed on organic and inorganic selenium forms for 60 days to enable evaluating the biochemical profile of tissues exposed to fipronil (FPN) insecticide. Diphenyl diselenide [(PhSe)₂] (3.0 mg/kg) and sodium selenite (Na₂SeO₃) (0.75 mg/kg) were used as organic and inorganic selenium forms, respectively. Overall, the adopted organic and inorganic selenium forms were similarly capable of reestablishing oxidant and antioxidant stress parameters close to control levels. Fish exposed to fipronil have shown decreased acetylcholinesterase (AChE) activity in brain and muscle tissues. Brain tissues of fish supplemented with Na₂SeO₃ or (PhSe)₂ diets presented reestablished AChE levels in comparison to those of fish fed on standard diet. Liver tissues of fish fed on standard diet presented decreased δ-ALA-D activity after their exposure to FPN, whereas diets added with two selenium forms were efficient in reestablishing the levels of standard diets. Therefore, (PhSe)₂ and Na₂SeO₃ have potential to be used as supplementation factors in diets to feed C. carpio.

Agricultural production has a major impact on the environment. Indeed, the emissions from agricultural machinery have a significantly negative impact on ambient air, thereby contributing to Climate Change. This study analyses combine harvesters and justifies their optimization in order to increase resource efficiency as well as reduce any negative impact on the environment. Data from 90 combine harvesters in Lithuania and Latvia from 2016 to 2018 is collected using telematics, and the parameters that directly influence engine exhaust emissions are analyzed, such as operation time, grain unloading method, fuel consumption, and auto-steering, according to the engine-operating modes of harvesting, transportation, and idling. Statistically reliable strong correlations can be found between harvesting time and idling time, as well as between fuel consumption during harvesting and idling modes. On average, roughly 20% of the operating time consists of idling and roughly 15% of transportation; moreover, roughly 14% of the diesel fuel is used per year in the aforementioned engine modes. In addition, the auto-steering function enables the efficient use of diesel fuel (average cost per combine harvester is reduced by 0.2 t year⁻¹), thereby reducing air pollution (pollution per combine harvester is reduced on average by 0.6 t year⁻¹). The results suggest telematics system data can be effectively used for data analysis, problem identification, and decision-making with respect to pollution prevention and optimizing combine harvester operation. Graphical Abstract

To assess the ecological risk resulting from an accidental gasoline spill upstream from a wetland, groundwater and sediment sampling was carried out during two campaigns at the 48th and 52nd months after the spill had occurred. In total, 21 groundwater monitoring wells in the affected area were sampled plus an additional reference well located upstream from the accident location. Seven sediment sampling points were selected inside the wetland, plus a reference point upstream from the accident. Physicochemical parameters, BTEX (benzene, toluene, ethylbenzene, m-xylene, p-xylene and o-xylene) and metal concentrations were analysed to estimate the chemical risk. Acute (Allivibrio fischeri, Daphnia similis, Hyalella azteca) and chronic (Artemia salina and Desmodesmus subspicatus) toxicity assays were performed with groundwater and sediments elutriate to determine the ecotoxicological risk. Results from groundwater indicated an extreme chemical level of risk in14 out of 21 monitoring wells. These 14 wells also exhibited free-phase gasoline and lead (Pb) concentrations above the threshold values adopted by this study. The presence of Pb, however, could not be associated with the gasoline accident. High acute and chronic toxicities were reported for the majority of wells. Conversely, the risks associated with the sediments were considered low in most sampling points, and the ecotoxicity found could not be related to the presence of gasoline. Groundwater flow modelling results have evidenced the migration of the contamination plume towards the wetland. Thus, to prevent contamination from reaching the protected area, more effective groundwater clean-up techniques are still required.

Diclofenac has been detected in water and terrestrial matrices, causing severe changes in the environment. This is due to the fact that it is one of the most widely used nonsteroidal anti-inflammatory drugs in the world. The advanced oxidation processes (AOPs) of photo-peroxidation and heterogeneous photocatalysis were tested in this work using UV-C and solar radiation to degrade diclofenac in aqueous solutions. To monitor the efficiency of the degradation processes an ultrahigh performance liquid chromatography with ultraviolet detection at a wavelength of 285 nm was applied. Both processes were found to be efficient (> 78%) after 60 min of treatment, being possible to determine the reaction kinetics for each one of them. Intermediate formation was also observed after 60 min which were also degraded by increasing the treatment time to 120 min. For the treatments using UV-C radiation, an order of 1.0 was observed, while the treatments that applied solar radiation obtained an order of 0.2 for the photocatalysis and 0.8 for photo-peroxidation.

Alkylphenols (APₛ)—nonylphenol (NP) and octylphenol (OP)—are well-known environmental contaminants due to their widespread application and have been identified as endocrine-disrupting chemicals. A novel APₛ-tolerant fungus designated F6 was isolated from the bottom sediments of the coastal part of the Eastern Gulf of Finland (Neva Bay) and was identified as Aspergillus tubingensis F6 based on ITS sequencing and morphological analysis. The APₛ presence caused morphological and ultrastructural changes in fungal cells. Major differences were detected in mitochondria, vacuoles, and cell walls. Nonenzymatic antioxidants—pigments, reduced glutathione, exopolysaccharides—played important roles in A. tubingensis F6 resistance to APₛ toxicity. A low level of lipid peroxidation showed that the protective effects of the antioxidant system were sufficient despite the fact that antioxidant enzymes activity levels were low. Another defense response employed by A. tubingensis F6 against the tNP- and 4-tert-OP-induced stress was based on the ability of the strain to efficiently utilize xenobiotics. After 120 h of cultivation, < 10% of APₛ (initially added to the culture at 100 mg/l) remained in the culture medium of A. tubingensis F6. The APₛ degradation by A. tubingensis F6 led to the formation of nontoxic products. These data indicate the potential role for A. tubingensis F6 in APₛ degradation in natural environments, as well as its possible biotechnological application in wastewater treatment to remove xenobiotics with endocrine activity. To our knowledge, this is the first report demonstrating that marine-derived fungus A. tubingensis strain is capable of utilizing branched-chain NP and OP.