Fluoride contamination in water is a global health concern. While many studies have used simulated fluoride-containing solutions in labs, few have conducted defluorination experiment on natural fluoride-contaminated water. In this study, we prepare three defluorination pellets (P1, P2, P3) using cement, sludge, and rice husk powder with mass percentages of 75%: 20%: 5%, 70%: 20%: 10%, and 65%: 20%: 15%, respectively, and tested their defluorination efficiency in water samples taken from the South Jiaolai River in Shandong Province, China. An outdoor experiment was conducted in May and June in Jiaozhou, Shandong Province, which lasted for 24 days. For each treatment, 10 g/L of pellets were added to 50 L of natural water samples with 3 replicates. The initial fluoride concentration of the water samples was 1.90 mg/L, and the fluoride concentration and pH value were measured every 3 days. SEM, EDS, XRD, and FTIR were used for analyzing potential defluorination mechanisms. The results showed that 3 types of pellets were effective in fluoride removal. On the 24th day, the fluoride concentrations in the water samples treated with pellets were significantly lower than that of the control group. The fluoride concentration in water samples treated with P1, P2, and P3 decreased to 0.74, 0.75, and 0.99 mg/L, respectively. AlF3 and MgF2 could be found in the composition of the pellets after the treatment of water samples, and hydroxylated metal oxides and CaCO3 both contributed to the defluorination process. The prepared pellets have potential for application in defluorination of fluoride-contaminated surface water.

The treatment of sanitary landfill leachate (LLe) is a complex and highly polluted wastewater with variable composition and high organic and inorganic contents. Continuous flow electrochemical processes have emerged as promising alternatives for effective and sustainable treatment. A laboratory-scale continuous flow electrocoagulation (CECo) process was operated without heating the reactor on LLe from the Seelong Sanitary Landfill under varying inlet flow rates (50, 100, 200, 300, and 400 mL/min) and current density (10, 20, 30, 40, and 50 mA/cm2). The results showed that the Seelong Sanitary Landfill contains stabilized leachate qualities. As the inlet flow rate increased, the color of LLe became less dark, and the removal of pollutants was enhanced. As the current density increased, the removal of COD increased from 20.62 to 27.96%, BOD5 from 23.31 to 38.03%, and NH3-N from 13.25 to 22.11%. The settling velocity and sludge volume index were 1.81 m/min and 253.85 mL/g, respectively, indicating the settling and compaction characteristics of the sludge. Excessive high flow rates resulted in hydraulic limitations and reduced contact time, negatively impacting treatment performance. Therefore, it is crucial future research focuses on further refining the non-heated CECo process and exploring synergistic treatment combinations including artificial intelligence to enhance pollutant removal efficiencies.Graphical Abstract

The aim of the present work was to study the possibility of coculture of the two halophytes Sesuvium portulacastrum–Sulla carnosa under saline and non-saline conditions with a special focus on plant vigour and phytodesalination potential. Plants were grown for 2 months in unperforated pots filled with agricultural soil added or not with 1.5 g NaCl. kg−1. Thereafter, shoots were harvested for growth, water status, and mineral composition. Soil samples were also analysed. Plant productivities and phytodesalination potentials were estimated based on shoot dry weights and sodium contents as well as soil soluble sodium contents. As grown for only 2 months in monoculture, S. carnosa could not desalinate the slightly saline soil, unlike S. portulacastrum, which extracted a quarter of the added sodium quantity. Nevertheless, such a noticeable phytodesalination capacity of S. portulacastrum did not reduce soil salinity and soluble sodium content. S. carnosa growth and productivity were enhanced by both salinity and coculture under non-saline conditions, which can be explained respectively by S. carnosa halophytic behaviour and probably a positive allelopathy exerted by S. portulacastrum. By contrast, a negative allelopathy seems exerted by S. carnosa under both saline and non-saline conditions. Under moderately saline conditions, both halophytes should be grown in monoculture. The stimulatory effect of S. portulacastrum on S. carnosa under non-saline conditions needs further investigations.

This study aimed to evaluate the water quality of Wulur Lake, the largest freshwater lake on the Indian subcontinent, taking into account spatiotemporal fluctuations in physicochemical parameters. The water samples were taken from five locations (Makhdomyari, Vintage, Ashtang, Matlab, and Ningle) for 3 years, viz., 2019, 2020, and 2021. The results of various physiochemical parameters during the entire study showed that the water quality of Wulur Lake has deteriorated due to the increased growth of macrophytes. The correlation analysis found significant positive and negative correlations between the studied parameters: temperature, depth, transparency, pH, conductivity, dissolved oxygen (D.O.), chloride, total alkalinity, hardness, calcium, nitrogen, phosphorus, and magnesium content. The principal component analysis (P.C.A.) demonstrated the most excellent match among the various physiochemical parameters, with two principal components explaining 63.5%, 63.8%, and 64.1% of the observed data variability in the sampling years 2019, 2020, and 2021 respectively. The Lake is becoming eutrophic, as evidenced by the low D.O. levels, increased nitrate-nitrogen and total phosphorus, high magnesium values, conductivity, total alkalinity, hardness, and calcium hardness. The Lake will likely continue to worsen and eventually become eutrophic if proper conservation measures are not implemented.

Biochar (BC) is a carbon-rich product obtained by heating biomass in a closed system with a finite amount of oxygen. BC has gained significant attention in agriculture as a soil amendment. This study investigated the effect of BC produced from agricultural bio-waste on soil physical and chemical properties and wheat and barley growth performance under rainfed conditions. The BC was applied at different rates before tillage at 0, 5, 10, and 15 t ha−1. The BC application significantly enhanced most soil-measured physical and chemical properties, increasing soil water retention capacity, soil nutrients, and saturated hydraulic properties. The growth performances of barley and wheat crops were enhanced by BC application, which significantly increased grain yield by around 6- and 2-folds at 15 t ha−1 compared to the control, respectively. The BC application demonstrated its usefulness in reducing the impact of drought conditions by maintaining better moisture content between rainfall events. Based on the output, we suggest that the BC application rate at 15 t ha−1 can be used to improve barley and wheat growth under rainfed conditions. Nevertheless, research is needed to investigate the effectiveness of BC from different feedstocks in improving soil properties in the field and plant development and performance.

The quality of water has a great impact on the life of aquatic species. The frequency of algal proliferation has increased all over the world due to changes in the water quality factors of the water systems. This study determined the correlation between Uroglena americana (U. americana) and water quality factors. U. americana mainly proliferated in late April at the surface level of the source water when the water temperature was in the range of 15.8–17.9 °C. Water temperature was negatively correlated with U. americana throughout the sampling period. In spring, the dissolved nitrogen (DN), dissolved organic carbon (DOC), fluorescence substance (peaks 1, 2, 3, 4, and 5), and electrical conductivity (EC) were positively correlated with the U. americana whereas the pH, dissolved oxygen (DO), oxidative reduction potential (ORP), turbidity, color, and dissolved phosphorus (DP) were negatively correlated. The total bacteria (16S rDNA) of source water showed a strong positive correlation (r = 0.66 at p = 0.05) with U. americana. The proliferation of U. americana also could be influenced by the associated microalgae species of source water. The Peridinium and Asterionella species were negatively correlated with U. americana, whereas the Euglena, Chlamydomonas, and Nitzchia species were positively correlated; among them, Euglena sp showed a significant positive correlation (r = 0.90, at p = 0.01) with U. americana. The obtained results of this study could be applied to the source water quality management and the optimization of the operating conditions of drinking water treatment plants to ensure the quality of drinking water.Graphical Abstract

Phytoremediation is one of the efficient and eco-friendly techniques which use different types of trees and plants with different mechanisms to remove pollutants. The current study was conducted to investigate the efficiency of Cynodon dactylon plant in removing phenol from the water environment by hydroponic method. According to the obtained results, the highest plant growth occurred in the concentration of 150 mg L−1 nitrogen as ammonium nitrate and 50 mg L−1 phosphorus as potassium dihydrogen phosphate. The maximum amount of phenol absorption by the plant occurred in 20 days. At the concentrations of 50, 100, and 150 mg L−1 of phenol, COD removal efficiency reached 87, 72, and 67%, respectively, and BOD5 removal efficiency reached 92, 86, and 80%, respectively. The findings showed that the investigated plant has high efficiency for phenol elimination from aqueous media and could be served as a suitable option to treat such contaminants from wastewater.

Studies of the influence of hydrocarbon rocket fuel kerosene T-1 on the physical and geochemical properties were carried out in laboratory circumstances on different types of soils: brown semi-desert soil designated as zone (U-25) located in Central Kazakhstan, mountainous brown desert soil zone (U-30) located in East Kazakhstan, and a model soil standard (control soil). The soil was treated with various concentrations (0.002–150.0 g/kg) of hydrocarbon rocket fuel kerosene T-1, while the contact time was 3, 10, and 30 days. Pollution with kerosene T-1 in concentrations 5.0–15.0 g/kg affects the hydraulic characteristics of soils from the U-25 zone, and the filtration rate decreases by 4–5 times. For the mountainous brown desert soil from the U-30 zone, the concentration of kerosene up to 15.0 g/kg does not affect the mechanical composition of the soil, as well as the availability of the main nutrients (potassium, phosphorus, nitrogen). According to the mechanical composition, both soils belong to medium loamy soils. It has been established that when soil is contaminated from the U-25 zone in concentrations 15.0–150.0 g/kg, the fraction from 1.0 to 0.05 mm increases by 4–5%, and the silty and clay fractions in the soil decrease.

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants appearing ubiquitously in the environment with potential impacts on human health. Urban environments tend to have elevated levels of PAHs throughout the atmosphere and soil. Within the Oklahoma City Metropolitan, soil was evaluated for carcinogenic PAH (cPAH) concentration and examined for potential factors influencing presence and magnitude especially in soils receiving direct rooftop runoff. An overall and comparative analysis was performed of PAHs in soils from ninety-two urban sites for a total of 184 soil samples. This cPAH load was compared between soils receiving rooftop runoff and paired reference samples using Wilcoxon Signed-Rank testing, as were rooftop materials (metal, tar, asphalt) and building types (residential, commercial, school) between sites using Kruskall Wallace tests. A majority of locations analyzed had levels of cPAHs above the U.S. Environmental Protection Agency’s soil screening level (SSL) including benzo[a]pyrene (BaP), which was representative of the cPAH concentrations. CPAH concentrations in soils directly receiving rooftop runoff (contact soils) were significantly greater than in paired reference samples. Roofing type did not vary in contributing to cPAH levels. Additionally, schools and commercial contact soils had significantly elevated levels of cPAHs and BaP as compared to residential contact soils. Soil in Oklahoma City Metropolitan had significantly elevated cPAH loads in samples receiving rooftop runoff, but not likely as the result of roofing material. In a post-hoc analysis, buildings used as schools included the most contaminated sites. School soil contamination should be further investigated.

The non-point source (NPS) nitrogen pollution of Huangshui Basin has posed a threat to the water security of the Yellow River. However, little attention has been paid to the lower reaches of Huangshui Basin, the buffer zone to the Yellow River, thus making it difficult to understand and manage the NPS nitrogen pollution in the area. Based on optimized Soil and Water Assessment Tool (SWAT) model, the NPS nitrogen pollution in the area was explored. It was found that in the lower reaches of Huangshui Basin, the NPS TN load showed a net increase and higher association with water yield, with total increase of 1836.49 t/year. And, the NPS TN load intensity of different sub-basins were among 0.02–10.32 t/km2/year. Moreover, the peak loads were mostly concentrated in the wet season. The NPS NH4–N load showed a net decrease, with a total reduction of 576.72 t/year, and the maximum reduction rate (6.81%) was found in Huangshui River section. Furthermore, through scenario simulation, the agricultural and rural activities showed higher impact on the NPS nitrogen pollution. Specifically, the NPS TN load was dominantly produced by agricultural activities, accounting for 45–97%. And the NPS NH4–N load was mainly resulted from livestock and poultry breeding, accounting for > 35%. Therefore, to promote the utilization of fertilizers and animal manure is essential to alleviate the NPS nitrogen pollution in the lower reaches of Huangshui Basin. Overall, this study is expected to provide an important support on further understanding of NPS pollution at a basin scale.

Public parks and open playgrounds are the most important compartments of the urban environment due to their role in sustaining the well-being of city residents, primarily through relaxation and recreation. To determine the occurrence, levels, and sources of 16 US Environmental Protection Agency (US EPA) priority polycyclic aromatic hydrocarbons (PAHs) and consequent human health risk, soil samples from 18 parks and playgrounds from Kruševac, a mid-sized city in Serbia, were collected and analyzed. The concentrations of PAHs were determined using gas chromatography-mass spectrometry. The total concentration of selected PAHs ranged from 14 to 121 µg kg−1, with a mean of 55 µg kg−1. The measured concentrations of individual PAHs were well below limits set by national legislation and were much lower than reported values for cities worldwide. Principal component analyses and positive matrix factorization were employed to identify possible PAH sources. Traffic emissions and coal, firewood, and natural gas combustion were identified as the main sources of PAHs in the analyzed soil. The most polluted soil samples were found in parks and playgrounds near busy roads and in the most densely populated city districts. A risk assessment procedure established by the US EPA showed no significant risk, either carcinogenic or non-carcinogenic, associated with exposure to PAHs in the soil for adults and children who use parks and open playgrounds for recreational purposes.

This study investigated treatment performance of an advanced adsorptive media in treating wastewater from an ethanol production plant for reuse in agriculture. The advanced adsorptive media consisting of zeolite, bentonite, laterite soil and coffee ground were put into 4 laboratory-scale reactors (each with 4 L in size). Treated effluent from an ethanol production plant was fed to these laboratory-scale reactors at hydraulic loading rates (HLRs) of 0.2, 0.8, 1.4 and 2.0 m3/(m2.d). The results showed the treatment efficiencies to decrease with increasing HLRs and the removal efficiencies of total suspended solids (TSS), total dissolved solids (TDS), color and chemical oxygen demand (COD) were 39–69%, 6–16%, 14–48% and 18–46%, respectively. The high treatment performance was observed at the HLR of 0.2 m3/(m2.d), suggesting adsorption and the main mechanism responsible for wastewater treatment. To investigate the effects of flow patterns on treatment performance of the advanced adsorptive media, 5 pilot-scale reactors (each with 24 L in size) were operated at HLRs of 0.8–2.0 m3/m2.d, and the patterns of influent feeding were down-flow, up-flow and in-series flow. Additionally, a commercial media (the commercial name is “Popper” or bentonite soil mixed with the mineral stone) was also put into a pilot-scale reactor and used as the control for data comparison. It was found that the series and down-flow patterns could achieve treatment efficiencies more than the up-flow pattern and the control reactor.

Increasing disruption of water toxicity takes our attention to remove hazardous organic pollutants like p-nitrophenol (PNP) and methylene blue (MB) using a photocatalyst, and for this, simple solvothermal technique was used to create Ce-doped ZnO nanoflowers with various concentration of cerium, calcined at 600 °C for two hours. An effect of different concentration of dopant on structural, morphological, optical, and photocatalytic properties of ZnO with different concentrations of cerium was determined by characterizing the as prepared samples by XRD, UV-DRS, PL spectroscopy, zeta potential, and FE-SEM equipped with (EDS). The flower-like morphology and composition of synthesized samples was confirmed by FE-SEM equipped with EDS. The successful degradation of p-nitrophenol (PNP) and methylene blue (MB) was achieved using cerium doped ZnO as a photocatalyst when compared to the host matrix ZnO under UV radiation. 1% Ce-doped ZnO exhibits higher degradation efficiency as compared to other dopant concentration. This diminished photodegradation was successfully explained using PL, zeta potential, and UV-DRS study. Thus, cerium doping makes ZnO a prospective photocatalyst for removing organic contaminant in water.Graphical Abstract

Due to efforts devoted to indoor air quality management, indoor volatile organic compound (VOC) concentrations, including those of benzene, toluene, and xylene, are generally below the thresholds prescribed by standards. However, few studies have examined the effects of combined indoor VOC exposures under long-term and low-concentration scenarios, which represents actual exposure conditions. Additionally, most experimental studies include individuals of one sex, usually male. Hence, we investigated sex differences and toxic interactions in Drosophila melanogaster mortality under low-concentration and long-term exposures to benzene, toluene, and m-xylene. The results showed that female flies were more vulnerable than male flies when exposed to m-xylene, individually. However, there was not sufficient evidence to demonstrate sex-related differences in mortality induced by binary VOC mixtures in this study. Furthermore, within the range of experimental concentrations employed, antagonistic patterns were observed for binary mixtures of benzene, toluene, and m-xylene. In addition, the degree of antagonism for toluene and benzene was related to toluene concentrations. Sex and the VOC concentration ratio might collectively influence the interactions between toluene and m-xylene.

To address the issue of marine pollution caused by microplastics, the Japanese government started charging for plastic shopping bags in July 2020 and the Plastic Resource Recycling Promotion Law (PRRPL) was passed in April 2022, thereby discouraging plastic use in Japan. However, even before these laws and regulations were established, companies and offices had begun starting to make voluntary efforts to reduce plastic use. Among these efforts, this study focused on the shift from plastic to paper materials and company efforts to lower plastic use. This study aimed to investigate the impact of the social perception of marine plastic pollution since 2018 on companies’ adoption of paper materials for containers and packaging. The companies reviewed may have used up to 236,699 tons of paper materials instead of plastic since 2018. This reduction in plastic consumption is expected to decrease emissions by up to 625,424 tons of carbon dioxide (tCO2) annually, as well as external costs by up to 180.7 million yen. Hence, the shift from plastic to paper materials through firms’ voluntary efforts since 2018 has helped to reduce plastic use and ameliorate the effects of global warming.

As a novel alternative to perfluorooctane sulfonate (PFOS), sodium p-perfluorous nonenoxybenzene sulfonate (OBS) has been widely applied in many industrial fields. However, there is limited information about its adverse effects on aquatic organisms. In this study, the developmental and cardiac toxicity of OBS and PFOS in early life stage of zebrafish (Danio rerio) were investigated. Results showed that 96 h-LC50 values of OBS and PFOS were 23.81 and 57.59 mg/L, respectively. Exposure to OBS and PFOS could lead to significantly inhibition of the hatching rate and embryo development. OBS and PFOS with concentrations higher than 5 mg/L induced significant malformations, such as pericardial edema and yolk sac edema. Furthermore, both OBS and PFOS exposure decreased the heart rate, stroke volume and cardiac output, indicating that the cardiac function of zebrafish was affected. Exposure to OBS and PFOS also caused oxidative stress in zebrafish embryos, resulting in significant decreases of SOD, CAT and GSH, and significant increase of the MDA content. The oxidative stress may consequently induce the cardiotoxicity by altering the expression of heart development related genes, nkx2.5, tbx5, gata4 and myh6. In summary, the results revealed that OBS and PFOS exposure could induce the developmental toxicity and cardiotoxicity in early life stage of zebrafish, and OBS might not be a safety alternative to PFOS.

The assessment of chloride salt release from sediments is important for environmental and water resource protection. However, the reliability of computational models for chloride salt release flux from cohesive sediment beds is limited because the models do not consider the fluidization and fine particle characteristics of cohesive sediment beds. In this study, 398 experiments were conducted to investigate the chloride salt release flux of cohesive sediment beds that had been fluidized to various degrees. The degree of fluidization was reflected by the magnitude of sediment yield stress. The authors found that sediment yield stress is a relevant and critical indicator of chloride salt release flux. The lower the yield stress, the higher the chloride salt release flux. The content and size of fine particles in cohesive sediment beds were indicated by the magnitude of surface coefficient of fine particles. The chloride salt release flux decreases with the surface coefficient of fine particles, and increases with temperature and the salinity difference between the cohesive sediment bed and the overlying water column. An empirical formula was proposed to calculate the chloride salt release flux from a cohesive sediment bed in quiescent water. The findings of this study provide valuable insights into the assessment and management of water salinization.

A polyextremophilic fungal strain, A. flavus QMS-8, previously isolated from the hypersaline soil taken from the rhizospheric region of the neem tree, Azadirachta indica (Meliaceae), was recognized as the proficient strain for decolorization of Acid Orange 52, a toxic dye employed in textile operations. A. flavus QMS-8 immobilized on Luffa cylindrica (Cucurbitaceae) attained 80.6% and consecutively complete dye degradation within a hydraulic retention time of 12–24 h in a stirred tank reactor even at salinities of 1–5% and environmental temperatures ranging in between 34 and 39 °C under optimized settings. The SEM micrographs revealed the attachment of fungal hyphae on L. cylindrica, while enzyme profiling demonstrated the participation of laccase (0.17 IU mL−1), manganese peroxidase (0.16 IU mL−1), and lignin peroxidase (0.06 IU mL−1) in the degradation of Acid Orange 52. The decolorized samples were assessed through a UV-Vis spectrophotometer and HPLC which did not provide any information about the formation of aromatic amines or any other metabolite. The values of biological oxygen demand, chemical oxygen demand, total dissolved solids, and total suspended solids were reduced from 2836, 3000, 3415, and 360 mg L−1 to 615, 1179, 916, and 145 mg L−1, respectively, and aligned closely with the established criteria set forth by the NEQ. Phytotoxicity and cytotoxicity assays of effluent treated in STR demonstrated a significant reduction in the toxic impact of dye on plants and microbial cells, suggesting that the luffa immobilized A. flavus QMS-8 employed in this study holds promise for mitigating the potentially harmful effects associated with Acid Orange 52. These results offer valuable insights into the efficacy and potential environmental benefits of the bioremediation approach for textile effluent investigated in this research.

The influence of different pH conditions and simulated inter-root environmental solutions on the release behavior of heavy metals (Cu, Pb, and Zn) from contaminated soils was investigated. The results indicate that heavy metal leaching from the soil is more likely to occur under acidic conditions and there is a risk of sustained presence of heavy metals in the inter-root solution. To address this issue, soil washing experiments were conducted, showing that the overall heavy metals removal efficiency by ethylenediaminetetraacetic acid disodium salt (EDTA) is higher than other agents such as citric acid, malic acid, HCl, and HNO3. Under the optimal conditions, the removal rates of Cu, Zn, and Pb from the soil are 43.9%,73.1%, and 41.5%, respectively. Single-factor experimental studies show a strong positive correlation between leaching concentration and temperature. Thermodynamic calculations suggest the feasibility of EDTA as a soil washing agent for remediation, as the process is found to be spontaneous, endothermic, and entropically favorable. The combined results of X-ray photoelectron spectroscopy (XPS) analysis and density functional theory (DFT) calculations suggest that EDTA is particularly effective in removing steady-state Pb, while citric acid has an insignificant effect on Pb removal. EDTA has a stronger ability to remove lead than citric acid attributed to the higher complexing strength of EDTA with Pb and the better water solubility of EDTA metal complexes. In addition, the removal efficiency of Zn and Cu with EDTA is significantly (p < 0.05) greater compared to that with citric acid.

Industrial and pharmaceutical activities are contributing to global environmental contamination. These pollutants having various physicochemical properties are harmful to aquatic organisms and ecosystems. Among daily discharged pollutants, heavy metals can be removed from wastewater by sorption process using natural clay minerals. Quick clays (QCs) are unique glaciomarine clays with unstable structures contributing to their high cation exchange affinity. With a high cation exchange affinity, QC clays could be used as adsorbents in wastewater treatment. QCs could also have a significant impact on the fate of pollutants in littoral ecosystems. However, no research has yet reported on the ability of QCs to adsorb and trap heavy metals. In this work, we investigated the kinetics, sorption isotherms, and hysteresis of copper (Cu) and cadmium (Cd) on three Canada quick clays and montmorillonite (MMT), mostly recognized as a reference clay. Kinetics and isotherms results were processed using different sorption models to assess the sorption and hysteresis parameters of these clays. QCs were characterized by a rapid uptake with an equilibrium time of 10 min for both metals. They showed high distribution coefficients (kd) ranging from 2520 to 51,740 mL·g−1 for Cu and 190 to 4590 mL·g−1 for Cd, respectively. The Freundlich sorption isotherm model showed better fits for sorption experimental data with a sorption capacity constant (kf) ranging from 3.41 to 10.74 mg·g−1·(L·mg−1)1/n for Cu and 0.60 to 1.07 mg·g−1·(L·mg−1)1/n for Cd. QC showed a similar or higher adsorption capacity for these metals compared to MMT. Cu and Cd adsorption on QC were respectively 10 and 2.5 times more important than on MMT. Results have shown a hysteresis process for Cu and Cd suggesting a sequestration process of these metals on QC.