Solutions with 0.65 mM of the antituberculosis drug isoniazid (INH) in 0.050 M Na₂SO₄ at pH 3.0 were treated by electro-Fenton (EF) and UVA photoelectro-Fenton (PEF) processes using a cell with a BDD anode and a carbon-PTFE air-diffusion cathode. The influence of current density on degradation, mineralization rate, and current efficiency has been thoroughly evaluated in EF. The effect of the metallic catalyst (Fe²⁺ or Fe³⁺) and the formation of products like short-chain linear aliphatic carboxylic acids were assessed in PEF. Two consecutive pseudo-first-order kinetic regions were found using Fe²⁺ as catalyst. In the first region, at short time, the drug was rapidly oxidized by ●OH, whereas in the second region, at longer time, a resulting Fe(III)-INH complex was much more slowly removed by oxidants. INH disappeared completely at 300 min by EF, attaining 88 and 94% mineralization at 66.6 and 100 mA cm⁻², respectively. Isonicotinamide and its hydroxylated derivative were identified as aromatic products of INH by GC-MS and oxalic, oxamic, and formic acids were quantified by ion-exclusion HPLC. The PEF treatment of a real wastewater polluted with the drug led to slower INH and TOC abatements because of the parallel destruction of its natural organic matter content.

This paper reports the degradation of 10 mg L⁻¹ Ametryn solution with different advanced oxidation processes and by ultraviolet (UV₂₅₄) irradiation alone with the main objective of reducing acute toxicity and increase biodegradability. The investigated factors included Fe²⁺ and H₂O₂ concentrations. The effectiveness of the UV₂₅₄ and UV₂₅₄/H₂O₂ processes were investigated using a low-pressure mercury UV lamp (254 nm). Photo-Fenton process was explored using a blacklight blue lamp (BLB, λ = 365 nm). The UV₂₅₄ irradiation process achieved complete degradation of Ametryn solution after 60 min. The degradation time of Ametryn was greatly improved by the addition of H₂O₂. It is worth pointing out that a high rate of Ametryn removal was attained even at low concentrations of H₂O₂. The kinetic constant of the reaction between Ametryn and HO● for UV₂₅₄/H₂O₂ was 3.53 × 10⁸ L mol⁻¹ s⁻¹. The complete Ametryn degradation by the Fenton and photo-Fenton processes was observed following 10 min of reaction for various combinations of Fe²⁺ and H₂O₂ under investigation. Working with the highest concentration (150 mg L⁻¹ H₂O₂ and 10 mg L⁻¹ Fe²⁺), around 30 and 70% of TOC removal were reached within 120 min of treatment by Fenton and photo-Fenton processes, respectively. Although it did not obtain complete mineralization, the intermediates formed in the degradation processes were hydroxylated and did not promote acute toxicity of Vibrio fischeri. Furthermore, a substantial improvement of biodegradability was obtained for all studied processes.

Our goal was to reconstruct soil recovery from Acid Rain based upon removal of stemflow at beech (Fagus sylvatica) stands of known historic and recent soil status. Fourteen beech stands in the Vienna Woods were selected in 1984 and again in 2012 to study changes in soil and foliar chemistry over time. A part of those stands had been strip cut, and to assess reversibility of soil acidification, we analyzed soils around beech stumps from different years of felling, representing the years when acidic stemflow ceased to affect the soil. Furthermore, it was hypothesized that changes of soil chemistry are reflected in the stemwood of beech. Half-decadal samples of tree cores were analyzed for Ca, Mg, K, Mn, Fe, and Al. Soil analyses indicated recovery in the top soil of the stemflow area but recovery was delayed in the between trees areas and deeper soil horizons. Differences in soil pH between proximal and distal area from beech stumps were still detectable after 30 years indicating that soils may not recover fully from acidification or do so at a rather slow rate. Stemwood contents indicated mobilization of base cations during the early 80s followed by a steady decrease thereafter. Backward reconstructions of soil pH and soil nutrients, building on regressions between recent stemwood and soil chemistry, could not be verified by measured soil data in 1984, but matched with declining cation foliar contents from 1984 to 2012. Dendrochemical reconstructions showed highest values in the 1980s, but measured soil exchangeable cation contents were clearly lower in 1984. Hence, we conclude that our reconstructions mimicked soil solution rather than soil exchanger chemistry.

Overland flow caused by rainfall is one of the critical factors influencing soil erosion and loss of soil nutrients. Therefore, the study on the mechanism and controlling measures of soil nutrient transport proposed is considered important. A simulation experiment was performed to investigate the effects of polyacrylamide application rates (0, 1, 2, 4, and 8 g/m²) and flow rates (400 ml/min, 600 ml/min, and 800 ml/min) on runoff, infiltration rate, soil losses, and the concentration of ammonium nitrogen (NH₄⁺) in runoff at loess slope (0.8 m (width) × 1.5 m (length) and 5°). As the results suggest runoff, sediment loss, and soil nutrient loss increased by increasing flow rate. Applicable amount of polyacrylamide (PAM) can effectively increase infiltration and reduce soil erosion, but excess amount of dissolved PAM would plug porosity of soil which could decrease the infiltration. The ammonia nitrogen loss amount was decreased with the increase of the PAM application rate. The ammonia nitrogen loss amount respectively decreased by 40.0%, 57.0%, 59.1%, and 63.4% with the PAM application rate of 1, 2, 4, and 8 g/m². The best performance with the coefficient of determination (R²) showed that the ammonium transport with runoff can be well described by the proposed model in flow scour experiments of this study. Furthermore, the model parameter b has a significant positive exponential relation with the total amount of sediment.

The intensity and frequency of cyanobacteria-dominated harmful algal blooms (cHABs) has been increasing. A key issue associated with cHABs is the potential to release cyanotoxins, such as microcystin. One of the primary methods for addressing cHABs in a reservoir is the application of algaecides. This research evaluated the impact of common environmental factors (i.e., Fe, total organic carbon) on the efficacy of a hydrogen peroxide-based algaecide to attain control of a targeted cyanobacterial population. The results found that sodium carbonate peroxydrate (SCP, trade name PAK®27) at half the manufacturer’s suggested application was effective at suppressing cyanobacteria for 2 weeks. For example, reactors that contained a full level of TOC and 1 mg/L Fe significantly decreased by 89% from 21,899 to 2437 ± 987 cells/mL (p < 0.05) by 2 days after treatment with half-dose SCP while reactors that contained the full-dose TOC and no SCP treatment depicted an increase in cyanobacteria population over the first week. Furthermore, as the cyanobacteria population decreased, the algal assemblage began to switch to being green algae dominant. Under the experimental conditions evaluated, Fe and total organic content did not interfere with the efficacy of SCP. SCP can provide effective control of cyanobacteria in a variety of environmental conditions.

With increasing concern related to sustainable chemistry, we investigated the biosorption of Pb²⁺ ions from aqueous medium using an environmental friendly and economic biosorbent Bougainvillea spectabilis (BS). The BS was modified effectively using citric acid by hydrothermal method. The biosorbent(s) was characterized by scanning electron microscope (SEM), energy dispersion X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), and point of zero charge (pHₚzc). Various process parameters including biosorbent dosage, time of contact, temperature, solution pH, and initial Pb²⁺ ions concentration were studied in batch mode. Kinetic modeling was performed to evaluate the kinetic data and results showed that the studied process followed the pseudo second order (PSO) kinetics. Equilibrium modeling was done using famous equilibrium models, i.e., Langmuir, Freundlich, Dubinin-Kaganer-Radushkevish, and Temkin in non-linear fashion to evaluate equilibrium data by varying initial Pb²⁺ ions concentration from 20 to 180 mg/L. Based on RMSE values, Langmuir model fits best. This paper also discusses thermodynamic parameters (i.e., enthalpy, entropy, and free energy) showing that the process was spontaneous and endothermic in nature. In comparison with BS (B. spectabilis), an appreciable increase in uptake capacity of CABS (citric acid modified B. spectabilis) was observed in sequestration of Pb²⁺ ions from aqueous medium showing advantage of citric acid modification making it industrially favorable and socially acceptable biosorbent for efficient removal of lead from water.

Deca-bromodiphenyl ether (BDE-209) regulates various aspects of spermatogenesis and male fertility through its effect on estrogen receptor α (ERα), but the underlying mechanism remains unclear. Because molecular mechanisms such as remodeling of the blood-testis barrier (BTB) play crucial roles in spermatogenesis, we investigated the disruptive effects of ERα agonists on the BTB in spermatogenesis. In this study, 0, 300, and 500 mg/kg/day of BDE-209 were administered to pregnant adult mice by oral gavage from gestation day 7 to postnatal day 21. SerW3 cells were treated with methylpiperidino pyrazole (MPP) for 30 min before being treated with 50 μg/mL of BDE-209. BDE-209 increases ERα in time- and dose-dependent manners and decreases formin 1 and BTB-associated protein in F1 male mice. Furthermore, BDE-209 impairs the structure and function of the BTB. Activation of ERα signaling could disrupt the BTB, leading to spermatogenesis dysfunction. The results identified the role of ERα in BTB disruption during spermatogenesis and suggested that BTB disruption occurs because of exposure to BDE-209, which could potentially affect spermatogenesis. In conclusion, Sertoli cells seem to be the primary target of BDE-209 in the perinatal period, and this period constitutes a critical window of susceptibility to BDE-209. Also, the SerW3 cell model may not be a particularly useful cell model for studying the function of the cytoskeleton.

Many recent studies have focused on the influencing factors of the ecological footprint, but less attention has been given to human capital. Human capital, which is based on education and rate of return on education, may reduce the ecological footprint since environmental issues are human-induced. The current study investigates the impact of human capital on the ecological footprint in India for the period 1971 to 2014. The outcomes of the newly developed combined cointegration test of Bayer and Hanck disclose the long-run equilibrium relationship between variables. The findings reveal a significant negative contribution of human capital to the ecological footprint. The results of the causality test show that human capital Granger causes the ecological footprint without any feedback. In addition, energy consumption adds to the ecological footprint, while the relationship between economic growth and ecological footprint follows an inverted U-shaped pattern. The findings unveil the potential to reduce the ecological footprint by developing human capital.

Denitrifying bioelectrochemical system provided an alternative technology for nitrogen removal, even power recovery from wastewater, and its nitrogen removal performance and intermediate accumulation were affected by the extracellular electron transfer modes and rate-limiting steps in denitrifying biocathodes. In the current study, the extracellular electron transfer modes and rate-limiting steps for nitrate reduction and nitrite reduction of denitrifying biocathode were investigated through cyclic voltammetry. When the cathode potential swept from 0.003 to − 0.897 V (vs. Ag/AgCl), denitrifiers were indispensable for electrochemical denitrification. Three peak potentials were found in the cyclic voltammogram of denitrifying biocathode, where E₁ (− 0.471 to − 0.465 V) and E₂ (− 0.412 to − 0.428 V) represented respectively nitrate reduction and nitrite oxidation while E₃ (− 0.822 to − 0.826 V) represented nitrite reduction. Nitrate reduction involved the direct electron transfer mode while nitrite reduction involved the mediated electron transfer mode. Intracellular catalytic reaction was the rate-limiting step for nitrate reduction, independent on the electrochemical activity of denitrifying biocathode and the nitrate supply. The nitrate supply posed an effect on the rate-limiting step for nitrite reduction. The mediator transfer was the rate-limiting step for nitrite reduction in the absence of nitrate. But both mediator transfer and intracellular catalytic reaction became the rate-limiting steps for nitrite reduction in the presence of sufficient nitrate.

1,3,5-Tris-(2,3-dibromopropyl)-1,3,5-triazine-2,4,6-trione (TDBP-TAZTO) is an emerging brominated flame retardant which is widely used in several plastic materials (electric and electronic equipment, musical instruments, automotive components). However, until today, no photochemical studies as well as the identification of possible phototransformation products (PTPs) were described in literature. Therefore, in this study, UV-(C) and simulated sunlight irradiation experiments were performed to investigate the photolytic degradation of TDBP-TAZTO and to identify relevant PTPs for the first time. The UV-(C) irradiation experiments show that the photolysis reaction follows a first-order kinetic model. Based on this, the photolysis rate constant k as well as the half-life time t₁/₂ were calculated to be k = (41 ± 5 × 10⁻³) min⁻¹ and t₁/₂ = (17 ± 2) min. In comparison, a minor degradation of TDBP-TAZTO and no formed phototransformation products were obtained under simulated sunlight. In order to clarify the photochemical behavior, different chemicals were added to investigate the influence on indirect photolysis: (i) H₂O₂ for generation of hydroxyl radicals and (ii) two quenchers (2-propanol, sodium azide) for scavenging oxygen species which were formed during the irradiation experiments. Herein, nine previously unknown PTPs of TDBP-TAZTO were detected under UV-(C) irradiation and identified by HPLC-(HR)MS. As a result, debromination, hydroxylation, and dehydrobromination reactions could be presumed as the main degradation pathways by high-resolution mass spectrometry. The direct as well as the OH radical-induced indirect photolysis were observed. Graphical abstract .