Natural Water Conditions Research Articles

Uniformly dispersed FeOOH nanoparticles supported on alumina-carbon nanosheets for Cr(VI) removal

The mesoporous alumina-carbon nanosheets supported FeOOH nanoparticles were prepared by a facile and cost-effective hydrothermal synthesis for Cr(VI) removal in the wastewater, based on the affinity and selectivity of FeOOH and the accelerated mass transfer of nanosheet structure. The prepared nanoparticles with a small size of 2–5 nm were uniformly dispersed over the alumina-carbon nanosheets, attributed to the metal interaction and mesoporous confinement. The acid property after the introduction of alumina induced a positive charge on the surface of the adsorbent, which could enhance the adsorption of negatively charged metal ions. The Cr(VI) removal efficiency with the Al/Fe ratios showed a similar volcano curve. When Al/Fe ratio was around 3.3 and pHpzc was about 7.1, the adsorbent exhibited the best Cr(VI) removal efficiency of 99.4 %, owing to a large specific surface area, and small nanoparticle size, combined with abundant moderate-strong acid content of 294.5 μmol NH3 g−1.The Langmuir model could describe the adsorption process well, and the kinetic data was consistent with Pseudo-second-order. The thermodynamics revealed that the reaction process was spontaneous and endothermic. The adsorbent maintained a high removal efficiency of more than 80 % after running for five cycles and kept over 95 % under ionic co-existence and natural water conditions. Therefore, this study provides a new insight into the rational construction of efficient adsorbents with low-cost Cr(VI) removal.

A Machine-Learning-Based Method for Identifying the Failure Risk State of Fissured Sandstone under Water-Rock Interaction.

The mechanical properties of fissured sandstone will deteriorate under water-rock interaction. It is crucial to extract the precursor information of fissured sandstone instability under water-rock interaction. The potential of each acoustic emission (AE) parameter as a precursor for instability in the failure process of fissured sandstone was investigated in this study. An experimental dataset comprising 586 acoustic emission experiments was established, and subsequent classification training and testing were conducted using three machine learning (ML) models: AdaBoost, MLP, and Random Forest (RF). The primary parameters for identifying the instability risk state of fissured sandstone include acoustic emission ringing count, energy (mV·ms), centroid frequency, peak frequency, Rise Angle (RA), Average Frequency (AF), b value, and the natural/saturated state of fissured sandstone: state. To enhance data utilization, a 10-fold cross-validation method was employed during the model training process. The machine learning models were developed and designed to identify the instability risk of fissured sandstone under the natural and saturated states. The results demonstrated that the established RF model was capable of identifying fissured sandstone instability risks with an accuracy of 97.87%. Feature importance analysis revealed that state and b value exerted the most significant influence on identification results. The Spearman correlation coefficient was utilized to assess the correlation between input features. This study can provide technical support to identify the risk of instability of fissured sandstones under both natural and saturated water conditions. Based on the models developed in this study, it is possible to implement an early warning method for instability in fissured sandstone that meets realistic working conditions. Compared with the traditional empirical and formulaic methods, the machine learning method can more quickly process huge amounts of AE data and accurately identify the damage state of fissured sandstone.

Magnetic composite photocatalyst NiFe₂O₄/ZnIn₂S₄/biochar for efficient removal of antibiotics in water under visible light: Performance, mechanism and pathway

The widespread presence of antibiotics in aquatic environments, resulting from excessive use and accumulation, has raised significant concerns. A NiFe₂O₄/ZnIn₂S₄/Biochar (NFO/ZIS/BC) magnetic nanocomposite was successfully synthesized, demonstrating significantly enhanced electron-hole separation properties. Comprehensive investigations were conducted to evaluate the impact of various parameters, including catalyst mass, pH, and the presence of co-existing ions on the composite's performance. The nanoparticles of NiFe₂O₄ (NFO) and ZnIn₂S₄ (ZIS) were found to improve the surface stability and sulfamethoxazole removal capabilities of porous biochar, while also demonstrating high total organic carbon removal efficiencies. •O₂⁻ and h⁺ were identified as the predominant reactive oxygen species (ROS) in NFO/ZIS/BC-4 during the degradation process. The degradation outcomes of sulfamethoxazole under natural sunlight and water conditions were consistent with laboratory findings, affirming the robust applicative potential of NFO/ZIS/BC. Density functional theory (DFT) calculations were performed to elucidate the photocatalytic mechanism and identify potential intermediate products. Additionally, the types of heterojunctions present in the system were characterized and discussed. After multiple iterations, NFO/ZIS/BC-4 maintained effective photodegradation capabilities through five cycles. This study presents an effective method for the treatment of antibiotics in aquatic environments, offering significant potential for environmental applications.

Photo-transformation of graphene oxide in synthetic and natural waters

Graphene oxide (GO) is widely employed due to its outstanding properties, leading to an increasing release into the environment and natural waters. Although some studies have reported on the photo-transformation of GO, its behavior in complex natural waters remains inadequately explored. This study demonstrates that different types of ions may promote the photoreduction of GO in the order of Ca2+ > K+ > NO3− > Na+ by interacting with the functional groups on the surface of GO, and the photoreduction is enhanced with increasing ion concentrations. Additionally, natural organic matter (NOM) can inhibit the photoreduction of GO by scavenging reactive oxygen species. However, with increasing NOM concentrations (≥ 5 mgC/L), more NOM adsorb onto the surface of GO through hydrogen bonding, Lewis acid-base interactions, and π-π interactions, thereby enhancing the photoreduction of GO. On this basis, our results further indicate that the combined effects of different ions, such as Ca2+, Mg2+, NOM, and other complex hydrochemical conditions in different natural waters can promote the photoreduction of GO, resulting in a reduction in oxygen functional groups and the formation of defects. This study provides a theoretical basis for assessing the long-term transformation and fate of GO in natural waters.

Fe doping strategy induces peroxymonosulfate activation by ZIF-67 through a non-radical reaction pathway with dominant 1O2 generation

Zeolitic Imidazole Framework-67 (ZIF-67), which can be large-scale synthesized under mild conditions, has been widely reported as a promising and efficient catalyst in peroxymonosulfate (PMS)-based advanced oxidation process. However, ZIF-67 typically activates PMS through a monotonous free radical reaction pathway, which limits its reusability, resistance to environmental interference, and degradation selectivity. In this study, controlled doping of Fe atoms into the lattice structure of ZIF-67 (FexCo1-x-ZIF) was employed, resulting in the nearly complete conversion of PMS to 1O2 through a unique non-radical pathway. Series of experiments, characterizations, and theoretical calculations were employed to elucidate the micro-level mechanism of PMS activation. The results indicate that the tetrahedral coordinated Co-N4 sites in ZIF-67 are transformed into unsaturated Co-N2 sites due to the competitive coordination effect upon the introduction of Fe. PMS adsorption is enhanced as both oxygen atoms bind simultaneously to the Co-N2 site, inducing the removal of a hydrogen atom from PMS and electron transfer from PMS to the Co-N2 site, thus facilitating the generation of 1O2. The 1O2-dominated non-radical degradation reaction enhances the excellent degradation performance, reusability, and environmental tolerance of the FexCo1-x-ZIF/PMS system under diverse natural water conditions, presenting significant prospects for practical applications.

Surface defect and carbonyl engineering of CNTs via oxygen-plasma etching: Oriented production of singlet oxygen from peroxymonosulfate activation

A facile oxygen-plasma strategy was used to engineer carbon nanotubes (CNTs) surface with defects and carbonyl groups for organic water decontamination. The plasma-treated CNTs (E-CNTs) displayed a remarkable efficacy to catalyze peroxymonosulfate (PMS) activation for degrading electron-rich pollutants across a broad range of pH levels and under natural water conditions. Moreover, the kinetic constant for E-CNTs was found to be 4.1 times that of raw CNTs, attaining 97 % 2,4-DCP degradation in 20 min. The in situ capturing by electron paramagnetic resonance, chemical probing, and selectively scavenging tests collectively reveal that singlet oxygen (1O2) was the dominant reactive species with 54.9 % contribution to 2,4-DCP removal. The structure–activity relationship analysis and density functional theory (DFT) revealed that defects and carbonyl groups were the intrinsic catalytic sites for PMS activation. A comprehensive degradation pathway was proposed based on the properties of pollutant and degradation products from HPLC-MS and DFT calculations. Based on the ECOSAR analyses, the toxicity of the treated water (degradation intermediates) dramatically declined except for a polymerized bipolymer TP6 (m/z = 266.9). This article provides a novel method to create PMS-oriented active sites on carbon materials for selective singlet oxygen production and water purification.

Synthesis and exploration of physical properties of nanobiochar synthesized from rice straw for its applications in arsenic remediation from contaminated water environments

Arsenic (As) is a widespread carcinogenic element that emerges due to geogenic and anthropogenic processes and poses detrimental effects on public health. Biochar is a carbonaceous, renewable, and sustainable material synthesized under low or absent oxygen. Thus, the present study explores the application of biochar obtained via pyrolysis at 500 °C for 2 hrs, followed by ball milling for 3 hrs at 500 rpm to obtain nanobiochar materials for As removal from contaminated environments. Characterization of biochar has been performed for physico-chemical analysis. Different functional groups, including hydroxyl, carboxyl, and alkene, are observable using Fourier Transform Infrared Spectroscopy, contributing to As removal from water. Scanning Electron Microscope analysis shows the porous nature of nanobiochar, which also contributes to remediation. Transmission electron microscope analysis shows an average particle size of nearly 28.12 nm. The As(V) removal efficiency was obtained with an adsorption capacity of 55.1 µg/g at pH 8 to mimic natural water conditions for 6 hrs of biochar-arsenic interactions. The possible adsorption mechanisms of As species on biochar surfaces are electrostatic attractive forces, surface chemical bonding, ion exchange, and precipitation. Future research must concentrate on applications of low-cost, renewable, and carbon material, i.e., biochar for decontaminating natural groundwater samples containing various emerging contaminants for safe and clean drinking water.

Neural networks to retrieve in water constituents applied to radiative transfer models simulating coastal water conditions

Estimation of chlorophyll (CHL) using ocean colour remote sensing (OCRS) signals in coastal waters is difficult due to the presence of two other constituents altering the light signal: coloured dissolved organic material (CDOM) and mineral suspended sediments (MSS). Artificial neural networks (NNs) have the capacity to deal with signal complexity and are a potential solution to the problem. Here NNs are developed to operate on two datasets replicating MODIS Aqua bands simulated using Hydrolight 5.2. Artificial noise is added to the simulated signal to improve realism. Both datasets use the same ranges of in water constituent concentrations, and differ by the type of logarithmic concentration distributions. The first uses a Gaussian distribution to simulate samples from natural water conditions. The second uses a flat distribution and is intended to allow exploration of the impact of undersampling extremes at both high and low concentrations in the Gaussian distribution. The impact of the concentration distribution structure is assessed and no benefits were found by switching to a flat distribution. The normal distribution performs better because it reduces the number of low concentration samples that are relatively difficult to resolve against varying concentrations of other constituents. In this simulated environment NNs have the capacity to estimate CHL with outstanding performance compared to real in situ algorithms, except for low values when other constituents dominate the light signal in coastal waters. CDOM and MSS can also be predicted with very high accuracies using NNs. It is found that simultaneous retrieval of all three constituents using multitask learning (MTL) does not provide any advantage over single parameter retrievals. Finally it is found that increasing the number of wavebands generally improves NN performance, though there appear to be diminishing returns beyond ∼8 bands. It is also shown that a smaller number of carefully selected bands performs better than a uniformly distributed band set of the same size. These results provide useful insight into future performance for NNs using hyperspectral satellite sensors and highlight specific wavebands benefits.

Efficient Removal of Paraquat Pollutants Using Magnetic Biochar Derived from Corn Husk Waste: A Sustainable Approach for Water Remediation

Due to the widespread production of maize, the waste created by this crop has become a serious concern. This study applied the concept of waste circulation to the production of magnetic biochar from corn husk waste to remediate paraquat-contaminated water. Magnetic biochar (MB) was produced by impregnating maize husks with iron and carbonizing the residue in a nitrogen environment. Carbonized MB at the temperature of 850°C (MB-01-850) exhibited a combination of microporous and mesoporous structures ([Formula: see text], [Formula: see text]), while biochar created only a microporous structure ([Formula: see text]). According to the findings, Fe(NO3)3 significantly affected the increase in mesopore formation after carbonization. In addition, biochar exhibits excellent magnetic responsiveness. MB-01-850 reached equilibrium within approximately 20 min in synthetic water. Batch adsorption studies showed that MB-01-850 had maximum adsorption capacities ([Formula: see text]) of 34.97 mg/g and 31.63 mg/g for synthetic and natural water, respectively. The unmodified biochar (without mesopores) had a [Formula: see text] of 4.08 mg/g. This indicates that the presence of mesopores improves the effectiveness of paraquat adsorption. Additionally, the adsorption performance of magnetic biochar exhibited no statistically significant variance when tested under natural water conditions. Furthermore, magnetic biochar demonstrates impressive regeneration capacity, allowing it to be regenerated almost entirely for a minimum of four cycles using a sodium hydroxide (NaOH) solution with a concentration equal to or greater than 0.5 M.

Non-radical mechanism of N-doped porous biochar derived from corn stalks for efficient peroxydisulfate activation

Biochar has demonstrated significant potential as an alternative to carbonaceous catalysts in peroxydisulfate (PDS) activation for the oxidation of organic pollutants. However, the catalytic performance of pristine biochar generally remains unsatisfactory due to its inert conjugated carbon framework and limited redox moieties. It is of great necessity to fabricate biochars with abundant effective sites to promote the degradation of pollutants mainly through the non-radical mechanism. Herein, corn stalk and melamine were selected as a precursor for preparing nitrogen-doped biochar (N-BC) through ball-milling and high-temperature pyrolysis under oxygen-limited conditions. Benefiting from the unique properties of nitrogen-doped biochar (N-BC), such as large specific surface area, well-formed oxygen-containing groups, and abundant structural defects, the 2,4-dichlorophenol (2,4-DCP) degradation efficiency reached 98.4% in 40 min by N-BC/PDS system. In particular, N-BC maintained excellent catalytic ability in both artificial and natural water conditions to efficiently degraded 2,4-DCP owing to its non-radical dominated degradation mechanism based on O2·-/1O2 and electrons transferring. This study will expand biochar application and provide new insights for PDS activation to promote the non-radical oxidation of organic pollutants.

Reproductive management of the mugilid Liza aurata and characterization of proximate and fatty acid composition of broodstock tissues and spawnings

The golden grey mullet (Liza aurata) is a promising species for aquaculture's sustainable expansion. However, the lack of sustainable juvenile provision, mainly related to the lack of reproductive control, is one of the most significant bottlenecks for further expanding the culture of this species. In many cases, mullet broodstock management needs the application of hormone treatments to induce gonadal maturation or spawning. However, no works are directly related to the broodstock collection, acclimation, and reproductive management of Liza aurata. On the other hand, the knowledge of essential fatty acids (EFA) requirements and mobilization patterns by the broodstock is a first step to designing appropriate feeding protocols and formulas, which are crucial for the success of reproduction and larval development.For these reasons, this study aimed 1) to describe for the first time the reproductive management of Liza aurata broodstock under controlled conditions and 2) to offer a first approach to the reproductive lipid metabolism of the former species.A selection of 22 Liza aurata broodstock from wild origin was acclimated in open seawater conditions. Additionally, the proximate and fatty acid composition of body tissues (gonads, liver, and muscle) of the initial wild population were evaluated, to be later compared with the profile of the eggs obtained after one year from the selected broodstock, for the first time described under cultured conditions.The results highlighted the feasibility for the obtention of natural spawnings from broodstock with a mean weight of 787 g and 604 g (females and males, respectively), at a sex ratio of 2:1 (females/males), under natural photoperiod and marine water conditions with temperatures decreasing from 20.4 ± 0.3 °C to 18.8 ± 0.4 °C.On the other hand, it was evidenced the crucial role of HUFA (highly unsaturated fatty acids) precursors for the gonadal development of Liza aurata, primarily for females. Additionally, the wild males' gonads presented a remarkable high content of HUFA, predominantly DHA (docosahexaenoic acid) (34% of the total fatty acids). In the eggs, significant variations appeared under captivity conditions, with lower levels of ARA (arachidonic acid) and EPA (eicosapentaenoic acid) and higher EPA/ARA and DHA/ARA ratios than the wild female gonad. Additionally, it was evidenced the significant role of the liver as a physiological reservoir of HUFA, which seem to be mobilized to the gonad during the maturation process.Present results may help obtain a better insight to adjust broodstock management conditions and feeds, contributing to a more sustainable aquaculture growth.

Potential effects of Cladophora oligoclora Decomposition: Microhabitat variation and Microcystis aeruginosa growth response

Excessive proliferation of filamentous green algae (FGA) is a new ecological problem in lake systems that have not yet reached a steady state. However, knowledge on how FGA decomposition affects the physical and chemical properties of microhabitats, and whether FGA decomposition stimulates the growth of harmful microalgae in the same niche and promotes the formation of harmful algal blooms remains unclear. In this study, we investigated the decomposing effect of a typical FGA, Cladophora oligoclora, on the density and photosynthetic capacity of Microcystis aeruginosa. C. oligoclora decomposition was characterized under different conditions, namely, unshaded and aerobic, unshaded and anoxic, shaded and anaerobic, and shaded and anoxic, which represented different environmental states in the sedimentation process of decaying C. oligoclora mats from water surface to sediment. The shaded and anaerobic treatment significantly decreased the dissolved oxygen and pH of the culture medium by 66.48 % and 7.21 %, respectively, whereas the conductivity and total organic carbon increased by 71.17 and 70.19 times compared with the control group, respectively. This indicated that the decomposing C. oligoclora deposited at the bottom under dark and anaerobic conditions in natural waters had the greatest impact on the lake environment. Further, the cell density of M. aeruginosa was higher than that in the control group with low concentration (10 % of decomposing solution), whereas the cell density and photosynthetic activity decreased significantly at high concentration of the decomposing solution. Fatty acids and phenolic acids were identified as the main Cyanobacteria-inhibiting active substances in the organic acid components of the decomposing solution. Furthermore, phenol, 4-methyl- and indole compounds were active organic lipophilic compounds in the residue and solution of decomposing C. oligoclora were difficult to degrade. Our findings will be valuable for understanding the succession relationships between FGA and cyanobacteria, which have the same niche in lake ecosystems.

Highly efficient microplastics removal from water using in-situ ferrate coagulation: Performance evaluation by micro-Fourier-transformed infrared spectroscopy and coagulation mechanism

Generation of microplastics (MPs), as a result of the increasing amount of plastic waste from human activities, is an emerging global concern that potentially threatens human health due to its intrinsic toxicity and ability to transfer pollutants. We examined the flocculation/coagulation for efficiently removing MPs (here, polyethylene (PE) and polyethylene terephthalate (PET)) in water by applying in-situ ferrate treatment, which exploits easy preparation and reduces toxic sludge production but has high coagulation efficiency. The PE and PET removal efficiency was evaluated by measuring the amounts of PE and PET in the as-treated supernatant using microscope equipped Fourier-transformed infrared spectroscopy. Overall, in-situ ferrate coagulation removed >80 % of PE and PET in a range of ∼0.9–3.6 mg/L of coagulant dose. In particular, >99 % of PE was removed with 2.7 mg/L coagulants, whereas PET removal efficiency reached 75 % at the highest dose (3.6 mg/L ferrate). However, the presence of organic humic acid (HA) significantly enhanced PET removal efficiency, reaching >99 % at the highest dose (3.6 mg/L ferrate). According to the mechanism study, HA remarkably promoted charge neutralization at low doses, corresponding to the zeta potential reaching zero. In particular, PE and PET exhibited different floc formations owing to ferrate coagulation. Ferrate closely and tightly adhered to the surface of PET, indicating that in-situ ferrate induced the adsorption of MPs. Based on the removal test and mechanism study, in-situ ferrate flocculation/coagulation processes are highly efficient for removing MPs in surface water containing low concentrations of natural organic matter. In the real surface natural water condition, >98 % of MPs removal efficiency was achieved by - twofold decreased ferrate dose (1.8 mg/L) without microfiltration membrane process.

Scaled-up multistage reverse electrodialysis pilot study with natural waters

A multistage reverse electrodialysis system was studied at the REDstack research facility (the Afsluitdijk, the Netherlands) for over 30 days to describe the performance of such configuration under natural water conditions. The experiments were done with two 0.22 × 0.22 m2 stacks in series comprising 32 cell pairs (3.1 m2 of membrane area) for stage 1 and 64 cell pairs (6.2 m2 membrane area) for stage 2. The total gross power density at the available salinity gradient was stable at around 0.35 W∙m−2. The total net power density, corrected for the initial pressure drop of the stacks, was 0.25 W∙m−2 at an energy efficiency of 37 %. Throughout the operation, due to increased stack pressure drop, the actual total net power density lowered to 0.1 W∙m−2. A distinct behaviour was found for multivalent ions in each stage. For stage 1, Ca2+ and SO42− were transported from the river water to the seawater side, so-called uphill transport. For stage 2, uphill transport was not found, in line with Donnan potential calculations. Stack autopsy revealed microorganisms with sizes ten times larger than the cartridge filter nominal pore size (5 µm) and biofilm covering part of the spacer open area, both contributing to the increasing pressure drop in the stacks. This study showed that stable gross power densities and high energy efficiencies were obtained from feeding natural waters to a multistage reverse electrodialysis system, independent of fouling. In addition, it emphasized the importance of maintaining pumping power losses low for a viable deployment of the technology.

Ferrocene-modified Uio-66-NH2 hybrids with g-C3N4 as enhanced photocatalysts for degradation of bisphenol A under visible light

Designing graphitic carbon nitride (CN) based heterostructured photocatalysts with high catalytic activity is highly desired for peroxymonosulfate (PMS) activation to degrade organic pollutants from water. Herein, a novel heterostructured composite (U-F@CN) consisting of ferrocene-modified Uio-66-NH2 (U-F) and CN was synthesized. The U-F@CN exhibited superior photocatalytic performance to degrade bisphenol A (BPA) in the presence of PMS under visible light. The experimental results indicated that BPA could be removed entirely by U-F@CN within 60 min under visible light irradiation. In addition, the outstanding photocatalytic activity could be maintained at high level in a wide pH range, appropriate temperature region and natural water condition. Benefiting from the good chemical stability, outstanding optical property and in-situ generation of interfacial heterojunction of U-F@CN, the interfacial transport of photogenerated charges could follow the Z-scheme mechanism, which can accelerate the charge separation and transport to yield abundant reactive active species (ROS) to efficiently active PMS and under visible light. This work provides a novel approach to design CN-based heterostructured photocatalysts with high stability and superior photocatalytic activity for environmental remediation.

Influence of protein configuration on aggregation kinetics of nanoplastics in aquatic environment

Aggregation kinetics of nanoplastics in aquatic environment are influenced by their interactions with proteins having different structures and properties. This study employed time-resolved dynamic light scattering (TR-DLS) to investigate the effects of 5 proteins (bovine hemoglobin (BHb), bovine (BSA) and human serum albumin (HSA), collagen type I (Col I), and bovine casein (CS)) on aggregation kinetics of polystyrene nanoplastics (PSNPs) under natural water conditions, which were simulated using various ionic strength (1-1000 mM NaCl and 0.01-100 mM CaCl2), pH (3-9), and protein concentration (1-5 mg/L of total organic carbon). The results indicated that the interactions between proteins and PSNPs strongly depended on electrostatic properties, protein structures, and solution chemistries, which induced distinct aggregation behaviors in NaCl and CaCl2 solutions. Electrostatic repulsion and steric hindrance dominated their interactions in NaCl solution by stabilizing PSNPs with the order of spherical BSA and disordered CS > heart-shaped HSA > fibrillar Col I; whereas positively charged BHb destabilized PSNPs with aggregation rate of 1.71 nm/s at 300 mM NaCl. In contrast, at CaCl2 concentration below 20 mM, proteins destabilized PSNPs following the sequence of HSA > BHb > Col I > BSA depending on counterbalance among double layer compression, cation bridging, and steric hindrance; whereas CS stabilized PSNPs by precipitating Ca2+ that inhibited charge screening effect. Both protein concentration and solution pH affected protein corona formation, surface charge, and protein structure that altered stability of PSNPs. Characterizations using fluorescence spectroscopy, circular dichroism, and two-dimensional correlation analysis spectroscopy showed fluorescence quenching and ellipticity reduction of proteins, indicating strong adsorption affinity between PSNPs and proteins. The study provides insight to how protein configuration and water chemistry affect fate and transport of nanoplastics in aquatic environment.

Electro-peroxone with solid polymer electrolytes: A novel system for degradation of plasticizers in natural effluents

Electro-peroxone (EP) reaction has been considered as a promising process for real effluent treatments. However, the use of the technology in natural water conditions is limited by low electrical conductivity and high operating costs. Herein, a novel electrochemical system was designed to overcome this constrain by coupling EP with a solid polymer electrolyte (EP-SPE). Performances of EP-SPE system were thoroughly evaluated by comparing the decomposition and energy efficiencies of various plasticizers in different systems. The EP-SPE system achieved 50% of pollutants mineralization in only 10 min with the electrolysis energy consumption of 1.0kWh·m−3, While the conventional EP system (not) adding salt compounds (CEP-(N) AS) need 30 (60) min to reach 50% of pollutants mineralization with 3.8(26.6)kWh·m−3. Kinetics and mechanisms of EP-SPE were investigated in detail, while electronic paramagnetic resonance (EPR) detection and kinetic model revealed the occurrence, transient concentration and degradation contribution of reactive oxidizing species (ROS). Furthermore, tests of variety of SPEs and natural waters demonstrated universal applicability of EP-SPE. Additionally, EP-SPE did not show any performance deterioration after 15 runs. Therefore, this work provides a feasible technology for plasticizer purification in natural water.

Hydrogeochemical Characteristics Refine the Conceptual Model of Groundwater Flow in Wood Buffalo National Park, Canada

Wood Buffalo National Park (WBNP), the largest national park of Canada, has unique and complex ecosystems that depend on specific water quantity and quality. We characterize groundwaters and surface waters in WBNP by determining their chemical compositions and water types, the dominant hydrochemical processes affecting their compositions, and their hydrochemical characteristics in relation to interpreted groundwater flow systems. Total Dissolved Solid concentrations in groundwaters and surface waters range from ≤10 mg/L to ≥300,000 mg/L. Four distinct water type groups are found: (1) Ca-SO4-type waters occur in multiple clusters across the area in outcrop areas of Devonian evaporites; (2) Na-Cl-type waters predominantly occur in the Salt plains region along the central eastern boundary, overlapping evaporite and carbonate-dominated bedrock formations; (3) Ca-HCO3-type waters dominate the Peace-Athabasca Delta-region in the south and most of the central region; and (4) “mixed” waters. Solutes in the waters originate from three main processes: dissolution of halite, dissolution of sulphate minerals, and dissolution of carbonates. The spatial occurrence of hydrochemical characteristics correlate with hypothesized groundwater flow systems, i.e., Ca-SO4 and Na-Cl-type waters coincide with discharge areas of intermediate to regional groundwater flow paths, and Ca-HCO3-type waters overlap with recharge areas. The findings of this study contribute to advancing knowledge on the hydrochemical characteristics of this remote and highly protected region of Alberta, Canada, and are important components of any further, comprehensive assessment of the natural water conditions.

Temperature and salinity effects on whole-organism and cellular level stress responses of the sub-Antarctic notothenioid fish Patagonotothen cornucola yolk-sac larvae.

This work aimed to evaluate the whole-organism and cellular level responses to different combinations of water temperature and salinity of the notothenioid Patagonotothen cornucola at the end of the yolk-sac larval stage. Egg masses of the species were collected in the wild and then maintained at natural water conditions (4°C and 30 PSU). Newly hatched larvae were placed in aquaria with different combinations of water temperature (4°C, 12°C, and 16°C) and salinity (15 and 30 PSU) during four days before yolk sac absorption. Larvae exposed to 12°C grew more in length than those exposed to 16°C, but yolk volume was more reduced in larvae exposed to 16°C than those exposed to 4°C and 30 PSU than of 15 PSU. In addition, a higher proportion of larvae exposed to 12°C and 15 PSU completely absorbed their yolk. Whereas the more tolerant larvae to high temperatures were those exposed to 16°C and 30 PSU, lipid peroxidation and protein oxidation were highest at natural and at 12°C and 30 PSU conditions, respectively. The nutritional status (as standardized DNA/RNA index-sRD -) was low in all cases, even at natural conditions (average sRD ~ 1). Our study suggests that, in the context of climate change, the mortality rate of yolk-sac larvae of P. cornucola would not increase due to temperature or salinity stress. However, indirect effects (such as habitat degradation or changes in food availability) would be critical after complete absorption of the yolk.

Hydrophobic natural deep eutectic solvent THY-DA as sole extracting agent for arsenic (III) removal from aqueous solutions

This study was aimed to develop a methodology for removal of toxic arsenite (As3＋) species from contaminated aqueous solution using hydrophobic natural deep eutectic solvent (NADES) as a sole extracting agent. Herein, thymol (THY) and decanoic acid (DA) based hydrophobic NADESs THY-DA (1:1), THY-DA (2:1) and THY-DA (1:2) were prepared. THY-DA (1:2) offers advantageous physicochemical properties in comparison of other two DESs, therefore, employed as the sole extracting agent for removal of As3＋ species in natural water conditions. More than 90 % extraction efficiency (E%) for As3＋ was attained for high (5 mg/L) as well as low (100 μg/L) concentration at optimal extraction conditions (100 mg of DES, 6 min sonication, pH 6.5–7, 25 °C). DES was characterised by nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDS) techniques were used to confirm the presence of arsenic in the DES phase. Physicochemical properties such as density, melting point, moisture and solubility of DESs were also investigated. The DES was regenerated using 0.1 M HCl as stripping agent and reused thrice without observing any significant drop in extraction efficiency (E%). The FTIR spectra of the DES phase were recorded before and after the extraction of As3＋ species to better comprehend the extraction mechanism.