Nanoparticles are among the particular materials produced by industrial activities; the release of these nanoparticles in natural ecosystems interacts with living organisms. Aquatic environment is the most common estuary waste medium for industrial and all human activities, the consequences may be highly effective on sea food species. Moreover, the potential in situ reduction of metallic ions by preexistent agents leads to nanoparticles which may cause hazardous effects. Many organisms become at risk especially those that use gills during respiration process such as bivalves. The study undertaken investigates the potential effect of silver nanoparticles obtained by green synthesis method on the gills of Ruditapes decussatus as a model. Nanoparticles have been synthesized using Ceratonia siliqua fruit extract as a reducing agent. The organisms have been chronically exposed to silver nanoparticles and the effects were biochemically evaluated. The tests performed show a typical behavior of catalase, glutathione reductase, and glutathione S-transferase activities that give information about the oxidative stress-induced malondialdehyde quantification, which reveals a possible membranous deterioration of the gills. Acetylcholinesterase expression has been qualified to be at a safe rate which implies the capacity of the animal to protect the cholinergic system.

In this study, an iron oxide-coated zeolite (IOCZ) nanocomposite was synthesized and used for the removal of U(VI) and As(III) from aqueous solutions using a batch system. Parameters such as various contact times, pH, competing ions (Cd²⁺, Co²⁺, and Cr³⁺), temperature, and initial concentrations of uranium(VI) and arsenic(III) were investigated. The experimental results were fitted to the Langmuir, Freundlich, and Dubinin–Radushkevich isotherms to obtain the characteristic parameters of each model. Results suggested that adsorption of U(VI) and As(III) by IOCZ was best modeled with the Freundlich isotherm. The kinetic experimental data fitted the pseudo second-order model better than the pseudo first-order model for both elements. Using the thermodynamic equilibrium constants obtained at different temperatures, various thermodynamic parameters, such as ΔG ᵒ, ΔH ᵒ, and ΔS ᵒ, were calculated. These parameters indicated that the process is spontaneous and exothermic in nature. It was noted that an increase in temperature resulted in a decrease of 8.5 and 27.5% for U and As removal, respectively. An increase in initial concentrations of U(VI) and As(III) from 10 to 100 mg L⁻¹ at pH 3 resulted in increased adsorption capacities (q ₑ) for both elements. The increases were from 1.247 to 20.10 mg g⁻¹ for U(VI) and from 3.115 to 54.18 mg g⁻¹ for As(V). The presence of competing ions such as Cd²⁺, Co²⁺, and Cr³⁺ enhanced the removal of As by 9.2% whereas the adsorption capacity of uranium decreased by 13.8%. This research demonstrated that IOCZ is a potential adsorbent for the removal of U(VI) and As(III) from aqueous solutions.

The promotive effect of constructed wetlands (CWs) with polyculture on treatment efficiency is still a controversial problem. Additionally, there is limited information regarding the influence of temperature on CWs. In this study, the influence of vegetation type, different NH₄ ⁺-N loading rates, and environmental temperatures on performance of CWs were investigated. Results of different vegetation type indicated that removal of NH₄ ⁺-N and total phosphorus (TP) in polyculture was higher than other CWs. In polyculture, tested nutrients had removal percentages greater than 94.5%. Results of different NH₄ ⁺-N loading rates demonstrated that NH₄ ⁺-N was almost completely removed (around 99.5%) in polyculture under both NH₄ ⁺-N loading rates. Temperature could substantially influenced the performance of CWs and the removal percentages of NH₄ ⁺-N, NO₃ ⁺-N, total nitrogen (TN), and TP in all CWs tended to decrease with a decline of temperature. Especially, a sharp decline in the removal percentage of NO₃ ⁻-N of all CWs (greater than 39%) was observed at low temperature (average temperature of 8.9 °C). Overall, the polyculture also showed the best performance with the decline of temperature as compared to other CWs. This study clearly documented that polyculture was an attractive solution for the treatment of domestic sewage and polyculture systems were effective for domestic sewage treatment in CWs even at low temperature (8.9 °C).

This study analysed the effectiveness of innovative (basalt meal, brown algae extract) and conventional (barley straw) substances which hypothetically alleviate the inhibiting effect of Cd²⁺ on biochemical properties of soil, with particular regard to the activity of arylsulfatase. An analysis of their potential was carried out based on the activity of arylsulfatase and the number of Pseudomonas sp. determined on the 25th and 50th days of the study. Cd²⁺ was applied in the following doses: 0, 4, 40, 80, 120, 160, 200 mg Cd²⁺ kg⁻¹ of DM soil, in the form of CdCl₂·2.5H₂O. A complex formulation of the issue was obtained from the presentation of biochemical properties using the RS (resistance of soil) index. Cadmium caused permanent adverse effects in the soil environment, inhibiting the activity of arylsulfatase and the yield of spring barley. The consequences of stress connected with increasing Cd²⁺ pollution were intensified by an elongation of the accumulation time of the tested metal in the soil. Chances for regeneration of the soil may be sought, most of all, with the application of straw and, to a lesser degree, with basalt meal. Brown algae did not meet the expectations for its potential. An increase in the studied parameters also resulted from sowing the soil with spring barley.

In this study, activated red mud was used to develop an effective adsorbent in order to remove a toxic azo dye (tartrazine E102) from aqueous solutions. To increase the adsorption capacity, the red mud was activated by acid-heat treatment using 20 wt.% HCl (RM-HCl). To establish the optimum operating parameters, the influence of pH, adsorbent dose, contact time, initial dye concentration, and stirring rate was investigated. The adsorption equilibrium was studied using Langmuir, Freundlich, Dubinin-Radushkevich, Temkin isotherm models, and the characteristic parameters for each adsorption isotherm were determined. The kinetics of the adsorption process was analyzed by means of pseudo-first-order and pseudo-second-order models. The maximum removal efficiency obtained under optimum conditions was 84.72%. These results were in accordance with the isotherm and kinetic data. The results suggested that tartrazine adsorption process follows the pseudo-second-order kinetic model and also that fits Langmuir isotherm model. The maximum monolayer adsorption capacity was 136.98 mg/g.

In this study, Auricularia auricular spent substrate (AASS) was modified by sodium hydroxide and prepared as biosorbents to remove lead(II) from aqueous solution. The batch experiments showed that the biosorption capacity and biosorption percentage reached 36.35 mg g⁻¹ and 72.7% at initial concentration of 50 mg L⁻¹, pH 5, contact time of 200 min, and biosorbent dosage of 1 g L⁻¹. The biosorption of lead(II) onto modified AASS well fitted with the Langmuir isotherm model and the pseudo-second-order kinetic model with the maximum adsorption capacity(q ₘₐₓ) of 49.53 mg L⁻¹. The biosorption was an endothermic reaction and a spontaneous process based on positive value of ΔH ⁰ and negative value of ΔG ⁰. Fourier transform infrared (FTIR) analysis illuminated that amino and hydroxyl groups could bind lead(II) on biosorbent surface. Sodium hydroxide modification might enhance physical adsorption by enlarging surface area and pore volume as well as chemical adsorption by increasing ion exchange and forming crystalline species demonstrated by microscopy (SEM-EDX) and X-ray diffraction (XRD) analysis. After four regeneration cycles, the biosorption capacity of modified AASS still kept at 17.35 mg g⁻¹.

The polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) are persistent environmental pollutants. Recently, there have been an increasing demand to assess different biomarkers as early alarming indicators of environmental pollution. This study is the first to investigate the effects of PCDD/Fs on acetylcholinesterase (AChE) activity and histopathology of the body wall (epidermis, circular, and longitudinal muscles) of earthworm Eisenia andrei (Oligochaeta, Lumbricidae) using acute filter paper toxicity test. It is also exploring the selected biomarkers as a potential tool for evaluating soil quality. Earthworms were exposed to 0, 0.5, 1.0, and 1.5 ng/cm² PCDD/Fs. The treated worms expressed progressive abnormal morphological signs with incrementing doses of dioxins, such as coiling, curling, and body swelling. At the highest dose, some worms demonstrated skin discoloration, loss of body segmentation, and body part detachment. The AChE activity was significantly decreased (p < 0.001) in all treated animals compared to control. The mixture induced circular muscle hyperplasia at 0.5 ng/cm². However, the mixture at 1.5 ng/cm² caused epidermal atrophy with cell pyknosis and necrosis in all layers of the body wall. Image analysis revealed significant reduction in the thickness of the epidermis (p < 0.001) at all doses with relative to control. Herein, we report that 48 h of acute exposure of E. andrei to dioxins/furans induced morphological changes, reduced the activity of AChE, and induced histopathological alterations. The outcomes can be utilized as endpoints that could be added to earthworm’s standardized short tests for ecotoxicity studies.

The selection of emergent plants is of primary importance during the construction of floating treatment wetlands (FTWs). Focusing on the comparison of the nitrogen removal, pot-culture experiments were carried out in floating treatment wetlands constructed with Phragmites australis and Acorus calamus in northeast China, a cold temperate zone. Nitrogen removal and transformation processes were investigated to explore the pathways and factors that influence the nitrogen removal. FTWs showed a high capacity for nitrogen removal. In water with TN concentrations of 9.63 and 4.58 mg L⁻¹, the average TN removal efficiencies of the FTWs constructed with P. australis were 91.5 and 84.2%, respectively, and those of FTWs constructed with A. calamus were 84.2 and 82.8%, respectively. Plant uptake accounted for 36.4 to 77.1% of total N removal. The average TN removal rates of P. australis systems in the first 2 days were 4.20 and 1.77 mg L⁻¹ day⁻¹ for treatments with TN concentrations of 9.36 and 4.58 mg L⁻¹, respectively, significantly higher than those of the A. calamus system, which were 1.75 and 1.04 mg L⁻¹ day⁻¹, respectively. Our results suggested that plant uptake was the main pathway for nitrogen removal in FTWs, and P. australis was a suitable emergent plant species for use in FTW construction in a cold temperate zone.

Among the measures used to manage mosquito populations and prevent human diseases, the application of pesticides is the global strategy mostly employed. To investigate the lethal and sublethal effects of insecticides used to control mosquitoes on amphibians (Rhinella arenarum, Rhinella fernandezae, and Physalaemus albonotatus), tadpoles were exposed to commercial formulations of temephos (Abate®), Bacillus thuringiensis var. israelensis (Introban®), and permethrin (Depe®). Their acute toxicity in terms of median lethal concentration (LC₅₀) and no- (NOEC) and lowest-observed-effect concentrations (LOEC) was evaluated. To assess the sublethal effects on behavioral endpoints, tadpoles were exposed to the NOEC-24-h value of each insecticide. After that, tadpoles were recorded and video-streaming data were processed by Smart® software. Based on LC₅₀, permethrin was the most toxic insecticide, followed by temephos and B. thuringiensis var. israelensis. Also, intraspecific and interspecific susceptibilities of tadpoles to insecticides were observed. Regarding behavior, the exposure of R. arenarum to the three insecticides had a significant effect on all behavioral endpoints. Two of the three swimming parameters evaluated for R. fernandezae were affected by permethrin, and in the end, only one behavioral pattern was altered in P. albonotatus after exposure to temephos. These results showed that tadpoles’ species were affected differently depending on the chemical properties of the pesticide and on a dose-response effect of the insecticides. Overall, our study suggests that further research is needed to quantify the potential damage of pyrethroid insecticides used for mosquito control on non-target aquatic organisms, mainly due to etho-toxic effects.

Hexavalent chromium (Cr(VI)) in wastewater is a great risk to the quality of water sources and to human health. Meanwhile, Chinese herb-extraction residues (CHER) are the by-products from the extraction process of Chinese medicine. This study investigated the use of CHER to adsorb Cr(VI) from aqueous solution. Results indicated that adsorption was maximum at solution pH of 2.0 while the Cr(VI) removal efficiencies for chuanxiong rhizome residue (CRR) and Chinese wolfberry residue (CWR) were 86.56 and 99.93%, respectively. Isotherm data were modeled by using Freundlich, Langmuir, and Temkin isotherms. The maximum monolayer adsorption capacities for CWR and CRR were 79.60 and 36.21 mg g⁻¹, while their corresponding adsorption capacities obtained from experimental data were 37.30 and 32.42 mg g⁻¹, respectively. However, Freundlich isotherm fitted the data well. Both adsorption and reduction of Cr(VI) to Cr (III) forms followed by complexation onto the adsorbent surfaces favored removing Cr(VI). The results also suggested that the abundant and cheaply available CRR and CWR can be used as efficient adsorbent materials for Cr(VI) removal from wastewater.