In the present study, the endocrine activity of the antiepileptic pharmaceutical carbamazepine (CBZ) in the crustacean Daphnia magna was assessed. To assess the hormonal activity of the drug, we exposed maternal daphnids and embryos to environmental relevant concentrations of CBZ (ranging from 10 to 200 μg/L) and to mixtures of CBZ with fenoxycarb (FEN; 1 μg/L). Chronic exposure to CBZ significantly decreased the reproductive output and the number of molts of D. magna at 200 μg/L. This compound induced the production of male offspring (12 ± 1.7 %), in a non-concentration-dependent manner, acting as a weak juvenile hormone analog. Results showed that this substance, at tested concentrations, did not antagonize the juvenoid action of FEN. Further, CBZ has shown to be toxic to daphnid embryos through maternal exposure interfering with their normal gastrulation and organogenesis stages but not producing direct embryo toxicity. These findings suggest that CBZ could act as an endocrine disruptor in D. magna as it decreases the reproductive output, interferes with sex determination, and causes development abnormality in offspring. Therefore, CBZ could directly affect the population sustainability.

Hydrocarbons are ubiquitous and persistent organic pollutants in the environment. In wetlands and marine environments, particularly in mangrove ecosystems, their increase and significant accumulation result from human activities such as oil and gas exploration and exploitation operations. Remediation of these ecosystems requires the development of adequate and effective strategies. Natural attenuation, biostimulation, and bioaugmentation are all biological soil treatment techniques that can be adapted to mangroves. Our experiments were performed on samples of fresh mangrove sediments from the Cameroon estuary and mainly from the Wouri River in Cameroon. This study aims to assess the degradation potential of a bacterial consortium isolated from mangrove sediment. The principle of our bioremediation experiments is based on a series of tests designed to evaluate the potential of an active indigenous microflora and three exogenous pure strains, to degrade diesel with/without adding nutrients. The experiments were conducted in laboratory flasks and a greenhouse in microcosms. In one case, as in the other, the endogenous microflora showed that it was able to degrade diesel. Under stress of the pollutant, the endogenous microflora fits well enough in the middle to enable metabolism of the pollutant. However, the Rhodococcus strain was more effective over time. The degradation rate was 77 and 90 % in the vials containing the sterile sediments and non-sterile sediments, respectively. The results are comparable with those obtained in the microcosms in a greenhouse where only the endogenous microflora were used. The results of this study show that mangrove sediment contains an active microflora that can metabolize diesel. Indigenous and active microflora show an interesting potential for diesel degradation.

The effect of direct current (DC) on phenol biodegradation under aerobic/anaerobic condition was investigated in this study using a bioelectrochemical reactor. It was found that phenol biodegradation was inhibited with current ranged from 10 to 40 mA. The growth of biomass was reduced to 43.2 ± 6.6 % for aerobic sludge and 38.6 ± 7.3 % for anaerobic sludge, but the loosely bound extracellular polymer substances (LB–EPS) were increased 91.2 ± 1.3 % for aerobic sludge and 62.8 ± 0.8 % for anaerobic sludge as the current increased from 10 to 40 mA. Adenosine triphosphate (ATP) content of aerobic sludge was also reduced 0.481 ± 0.04-fold and 0.512 ± 0.05-fold lower and 1.34 ± 0.13-fold higher than that of the control when the current was increased from 10 to 40 mA. The results of phosphate buffer saline adding treatment indicated that lower pH caused by a DC above 10 mA was responsible for the reduced phenol biodegradation, leading to the reduction of biomass. However, lower intensity of current (5 mA) had no significant impact on phenol degradation rate, pH, LB–EPS, ATP content, and cell growth of aerobic/anaerobic sludge. These results give us a more detailed understanding of the effects of electricity on the treatment of phenol containing wastewater.

Adsorption of arsenic (III, V) from aqueous solution onto the synthesized α-Fe₂O₃/MCM-41 nanocomposite adsorbent, as function of contact time, initial concentration of the solution, temperature, pH, and presence of other anionic species, has been investigated. Characterization of adsorbent was performed via XRD, FT-IR, TGA, TEM, and N₂ adsorption–desorption techniques. The synthesized adsorbent belonged to the group of mesoporous materials with the mean pore diameter of 2.37 nm, specific surface area of 507.5 m² g⁻¹, and total pore volume of 0.571 cm³ g⁻¹. The experimental data were analyzed by Langmuir, Freundlich, and Dubinin-Radushkevich (D–R) adsorption isotherms. Based on Langmuir isotherm, the maximum adsorption capacities at 298 K in the concentration range of 2–200 ppm were 133.3 and 102.1 mg g⁻¹ for As(ш) and As(v), respectively. The adsorption experiments at different contact times indicated that the kinetics of adsorption accurately followed the pseudo-second-order rate equation. Thermodynamics parameters were calculated, and it was found that the adsorption process was spontaneous, exothermic, and favored at lower temperatures. The capability of regeneration and reusability of adsorbent was also examined in alkaline solutions.

Treatability studies in real contaminated soils are essential to predict the feasibility of microbial consortium augmentation for field-scale bioremediation of contaminated sites. In this study, the biodegradation of a mixture of seven PAHs in a manufactured gas plant (MGP) soil contaminated with 3967 mg kg⁻¹ of total PAHs using novel acid-, metal-tolerant, N-fixing, P-solubilizing, and biosurfactant-producing LMW and HMW PAH-degrading bacterial combinations as inoculums was compared in slurry- and solid-phase microcosms over natural attenuation. Bioaugmentation of 5 % of bacterial consortia A and N in slurry- and solid-phase systems enhanced 4.6–5.7 and 9.3–10.7 % of total PAH degradation, respectively, over natural attenuation. Occurrence of 62.7–88 % of PAH biodegradation during natural attenuation in soil and slurry illustrated the accelerated rate of intrinsic metabolic activity of the autochthonous microbial community in the selected MGP soil. Monitoring of the total microbial activity and population of PAH degraders revealed that the observed biodegradation trend in MGP soil resulted from microbial mineralization. In the slurry, higher biodegradation rate constant (k) and lower half-life values (t ₁/₂) was observed during bioaugmentation with consortium N, highlighting the use of bioaugmentation in bioslurries/bioreactor to achieve rapid and efficient bioremediation compared to that of a static solid system. In general, natural attenuation was on par with bioaugmentation. Hence, depending on the type of soil, natural attenuation might outweigh bioaugmentation and a careful investigation using laboratory treatability studies are highly recommended before the upscale of a developed bioremediation strategy to field level.

Selective adsorbent of benzene, toluene, ethylbenzene, and xylenes (BTEX) was developed based on mesoporous silica materials, RH-MCM-41. It was synthesized from rice husk silica and modified by silane reagents. The silane reagents used in this study were trimethylchlorosilane (TMS), triisopropylchlorosilane (TIPS), and phenyldimethylchlorosilane (PDMS). Physiochemical properties of synthesized materials were characterized by small-angle X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), and surface area analysis. Materials packed in passive air sampler were tested for BTEX uptake capacity. The tests were carried out under an influence of relative humidity (25 to 99 %). Overall, RH-MCM-41 modified by TMS outperformed compared to those modified by other silane agents. The comparative BTEX adsorption on this material and commercial graphitized carbon black was reported.

Combining bioassays and analytical chemistry screenings is a powerful approach to assess emerging organic micropollutants which are the main contributors to toxic potentials in complex mixtures of water matrices. The aim of this study was to assess the cytotoxic effect of the occurrence of emerging organic micropollutants discharged into river water through industrial wastewater and treated effluents. The cytotoxic effects of surface water, treated effluents, and industrial wastewater were assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Then, organic micropollutants of various chemical groups were identified using a detailed non-target screening based on gas chromatography coupled with a mass spectrometry detector (GC/MS). A significant cytotoxic effect on human intestinal epithelial Caco-2 cells was observed for all the samples. Caco-2 cell viability decreased by 17.99, 33.77, and 24.54 % for surface water, treated wastewater, and industrial water, respectively. The organic chemical compounds responsible for this toxic potential were identified using non-target chemical screening. Statistical correlation between cytotoxicity and the presence of emerging contaminants revealed that the cytotoxic effect was mainly due (r ≥ 0.42) to the occurrence of cyclopentasiloxane, decamethyl and cyclohexasiloxane, dodecamethyl, D-limonene, and ergoline-8-methanol, 8,9-didehydro-6-methyl while cytotoxicity was highly negatively correlated (r ≤ −0.42) to 2-ethylhexyl salicylate, 3-isopropoxy-1,1,1,7,7,7-hexamethyl-3,5,5-tris(trimethyl siloxy)tetrasiloxane, 6-acetyl-1,1,2,4,4,7-hexamethyltetralin, and (3-aminopropyltriethoxysilane. Seventy-six other compounds detected by GC/MS showed no correlation to cytotoxicity.

Permeable pavements mitigate the impacts of urbanization on surface waters through pollutant load reduction, both by sequestration of pollutants and stormwater volume reduction through exfiltration. This study examined the non-winter water quality performance of two side-by-side permeable pavements in the Ohio snowbelt. The permeable interlocking concrete pavements were designed to drain impervious catchments 2.2 (large) and 7.2 (small) times larger than their surface area, were located over clay soils, and incorporated the internal water storage design feature. Nutrient reduction was similar to past studies—organic nitrogen and particulate phosphorus were removed through filtration and settling, while dissolved constituents received little treatment. Because of 16 and 32 % volume reductions in the small and large installations, respectively, nutrient loads were often significantly reduced but generally by less than 50 %. Aluminum, calcium, iron, magnesium, lead, chloride, and total suspended solids (TSS) concentrations and loads often increased after passing through the permeable pavements; effluent TSS loads were three- to five-fold higher than influent TSS loads. This was apparently due to seasonal release of clay- and silt-sized particles from the soils underlying the permeable pavement and inversely related to elapsed time since winter. The application of de-icing salt is thought to have caused deflocculation of the underlying soils, allowing particulates to exit with stormwater as it discharged from the underdrain of the permeable pavements. By autumn, both permeable pavements discharged metals and TSS concentrations similar to others in the literature, suggesting the de-icing effects lasted 3–6 months post-winter. Sodium may substantially affect the performance of permeable pavements following winter de-icing salt application, particularly when 2:1 clay minerals, such as vermiculites and smectites, predominate.

This work reported a comparative study on the electrochemical incineration of nitrilotriacetic acid (NTA) in the presence of different supporting electrolytes (Na₂SO₄ and NaCl). Galvanostatic electrolyses were conducted in an undivided electrochemical cell containing boron-doped diamond (BDD) anode and platinum cathode. Initial solution pH, flow rate, applied current density, and supporting electrolyte concentration were selected as variables, besides the mineralization efficiency of NTA that was selected as response. Central composite rotatable design and response surface methodology were employed here to examine the statistical significance of the selected variables, as well as to determine the optimal conditions of the degradation process. Under the same operating conditions, two regression models were thus constructed to illustrate the differing impact of supporting electrolytes in BDD anode cells. The kinetics for NTA degradation followed different reaction orders for the two scenarios (in the absence and presence of NaCl), indicating the complex interaction between hydroxyl radicals and active chlorine. Despite this, the experimental results demonstrated that effective mineralization of NTA might also be achieved in the presence of chlorides (of lower concentrations). Besides, in the case of chlorides, the average mass transfer coefficient of the system was found to be strongly dependent on the initial solution pH. Lastly, a plausible reaction sequence concerning the electrolytic oxidation of NTA in chloride media was also proposed.

Phosphorus (P) loss from diffuse sources remains as the main cause of freshwater eutrophication in agricultural regions. The amount of land used for different agricultural practices may be a strong explanatory factor for the P loading to runoff waters. A prerequisite is that the effect of changes in land use on P levels in surface waters needs to be ascertained and quantified. In this study, a comprehensive approach has been developed to explore the environmental consequences of P levels in receiving water with corresponding land use change in a heavily agriculturally influenced watershed. A coupled simulation using Dyna-CLUE model with grey relational analysis (GRA) and grey model GM (1,1) model was employed to stimulate spatial distribution and area demand. Besides, a comprehensive land use index with degree of P saturation (DPS%) as weight coefficient was developed to examine the statistical and spatial relationships of land use and P levels in receiving waters on regional watershed. Moreover, in order to evaluate the practical impact of land use change on water quality, a planned emigration and watershed ecological reconstruction planning were designed into the scenarios. The potential of changes in land use as an abatement action to curb eutrophication was evaluated by modelling the effect of issued emigration and ecological restoration programs in the local watershed of the Yuqiao water reservoir in northeastern China. Kappa indexes above 0.85 for the validation period verify that the coupled land use change model is able to simulate the effect of the abatement actions on land use. Scenario predictions reveals that local emigration and a comprehensive ecological restoration project as abatement actions could significantly decrease contents of P in receiving surface waters: Relative to year 2012, total P and orthophosphate could be reduced by 36 and 45 %, respectively, by the end of year 2018. This modelling approach can, with moderate modifications, also be adapted to other watersheds. The model developed in this study can thus be used by environmental managers as a tool to identify risk for P loss from diffuse sources within a watershed and assist policy makers to assess the effect on P losses by implementing abatement actions that changes land use.