Natural Water Environment Research Articles

Adsorption potential of spherical ZnO particles for sufficient antibiotic removal: isotherm, kinetic and thermodynamics

Due to the improvements of pharmaceutical industry, tetracycline (TC) is commonly detected in natural water environments, resulting in significant adverse impacts on living species. In this study, the TC adsorption over commercial spherical zinc oxide (ZnO) samples was systematically examined by considering adsorption isotherm models, kinetic model and thermodynamic behavior. The Langmuir kinetic model displayed the highest correlation coefficient (R2 = 0.97) with a maximum adsorption capacity of 86.35 mg/g. According to the results of the kinetic studies, the adsorption could be driven by both the bulk transfer of adsorbate molecules towards the adsorbent surface within the solution and chemisorption on the surface and inside the pores. In addition, the TC adsorption on the ZnO particles promoted by increasing temperature. The commercial spherical zinc oxide can be considered as a sustainable strategy to eliminate the emerging toxic contaminant of tetracycline.

In-situ formation of La2O2CO3 uniformly immobilized on biomass-derived carbon aerogel for enhanced phosphate removal

In the face of the dual pressures of eutrophication and phosphorus shortages, it is of utmost importance to efficiently remove and recover phosphate from wastewater. In this study, waste-biomass-derived carbon aerogel (CA) was utilized as a dispersing carrier for lanthanum (La), resulting in the successful in-situ generation of an La2O2CO3 (La3.5-CA-450) phosphate adsorbent on the CA matrix. The results demonstrated that the introduction of CA as an adsorbent led to abundant carbon defects and pore structures, which significantly enhanced its performance. Moreover, through the coordinated pyrolysis of CA and La3+, CO32−, capable of exchanging with PO43−, was generated, thereby contributing to the exceptional phosphate adsorption capacity exhibited by the adsorbent. Specifically, La3.5-CA-450 displayed a high phosphate adsorption capacity of 155.8 mg P/g (272.4 mg P/g La), with the molar ratio of P to La being 1.22:1, indicating a high utilization efficiency for La. The adsorbent exhibited exceptional performances in terms of selectivity, renewability, efficient use in natural water environments, and robust application in a broad range of synthetic availability. This research adheres to the green concept “using waste to treat waste” while providing a novel approach for preparing efficient La-based phosphate adsorbents.

Layered bismuthene forming the interfacial pathway for rapid charge transfer in CuNb13O33/g-C3N5 photocatalyst for enhancing ciprofloxacin degradation

The objective of the present research was to examine the usefulness of the photocatalytic degradation process in removing the ciprofloxacin drug from wastewater, which is difficult to remove from waterbodies. To tackle this difficulty, a ternary copper niobium oxide/carbon nitride/layered bismuthene heterostructure (CuNb13O33/g-C3N5-L-Bi) composite was developed by an intuitive solvothermal process. layered bismuthene (L-Bi) was prepared using a unique ball milling approach. According to the results of the characterization, adding L-Bi and g-C3N5 with a low band gap to the original band structure of CuNb13O33 makes it more efficient. After 120 min of irradiation, the modified CuNb13O33/g-C3N5-L-Bi sample significantly improved ciprofloxacin degradation, resulting in a degradation rate of 98 %. In addition, the impact of the catalyst that has been created on the removal of ciprofloxacin at various pH, catalyst dosages, and scavengers was also examined, demonstrating the catalyst’s suitability for purifying natural water environments. A detailed study of the steps used to break down ciprofloxacin has shown that many active species are involved, with a focus on the important roles played by reactive oxidative species (ROS). Thus, this study introduces a novel combination of layered bismuthene photocatalysts for environmentally friendly degradation of antibiotics.

An orientational graphene/bamboo evaporator for efficient solar-powered steam generation and desalination

Solar-powered steam generation and desalination by interfacial solar steam generation (ISSG) are promising techniques for addressing the freshwater shortage. However, the insufficient conversion efficiency and complex pollutant components confine its further extension and application. This study innovatively constructs an orientational graphene/bamboo evaporator (GBE), maintaining a solvent-accessible surface area and reducing vaporization enthalpy by selective delignification and torrefaction. The GBE device features a channel oriented from bamboo, consolidating the parallel architecture with multilayer biofilm filtration that guides efficient bulk-water pumping, steam release, and pollutant interception. The GBE demonstrates full-spectrum optical absorption at 90.5 % and 33.4 s response time while maintaining operational stability across different salt concentrations and natural water environments. The GBE achieved an evaporation rate of 1.53 kg m-2h-1as 4.34 enhancement factor under 1 kW/m−2(−|-) illumination, surpassing microplastics (99.84 %) and tetracycline (99.87 %) desalination. This work provides a high-performance and innovative approach to bamboo evaporator design, offering a viable and alternative method to address freshwater shortage.

Efficient degradation of ciprofloxacin by innovative VUV/BN system: Kinetics, mechanism and toxicity assessment

Given the increasing emergence of widespread fluoroquinolones (FQs) in natural water environments and the limitations of traditional vacuum ultraviolet (VUV) systems for water decontamination, an innovative VUV/BN system was developed for the degradation and detoxification of ciprofloxacin (CIP) in this work. Unlike the VUV system, which primarily relies on hydroxyl radicals (·OH), the VUV/BN system significantly enhances the concentration of singlet molecular oxygen (1O2) to target the piperazine ring of CIP, achieving a defluorination efficiency of 98.88 % within 60 min. The degradation rate constant for CIP was found to be 2.76 times greater than that of the traditional VUV system. Additionally, varying concentrations of reactive species (RSs) in the VUV and VUV/BN systems resulted in distinct CIP degradation pathways. Due to the high selective oxidation capacity and environmental compatibility of 1O2, the VUV/BN system demonstrated excellent adaptability to environmental factors, maintaining stable operation in complex water matrices. Furthermore, the system exhibited high degradation capacity for CIP even in the fifth cycle, confirming its exceptional stability and reusability. The economic feasibility of the VUV/BN system was confirmed by its low electrical energy per order (EEO). This study underscores the potential of VUV/BN systems and enhances the understanding of CIP photodegradation.

Poria cocos-derived carbon dots for parallel detection of Cr6+/Fe3+ in complex environments with superior sensitivity

Multifunctional sensor capable of parallel sensing is of great importance thanks to their wide applications and great practicality. In this report, Poria cocos-derived carbon dots (CDs) were adopted for the development of multifunctional sensor for the parallel detection of Cr6+ and Fe3+ with superior sensitivity and applicability. Specifically, extremely low limit of detection (LOD) of 1.07 × 10−3 nM and 1.98 × 10−3 nM were achieved for Cr6+ and Fe3+, respectively. Systematic mechanism explorations revealed that the highly sensitive detection of Cr6+ was attributed to an efficient inner filtering effect (IFE), while the sensing of Fe3+ was realized due to a strong static quenching process. Furthermore, the assay was found to be extremely versatile, achieving the reliable detection of Cr6+ and Fe3+ in multiple natural water environments and even biological environment. Utilizing the different reactions of Cr6+ and Fe3+ towards masking reagents, a logic gate that could effectively eliminate the mutual interference of Cr6+ and Fe3+ was successfully designed.

Occurrence and fate of five representative neonicotinoid insecticides across different wastewater treatment plants and the impact on receiving water bodies

Neonicotinoids (NEOs), despite their widespread use as insecticides, exhibit a notable knowledge deficit in regards to their presence in wastewater treatment plants (WWTPs) and their surrounding environments. This study delves into the presence and disposition of 5 NEOs: Thiamethoxam (THM), Clothianidin (CLO), Imidacloprid (IMD), Acetamiprid (ACE), and Thiacloprid (THA) across 3 domestic WWTPs and their receiving waters. Notably, THM, CLO, and ACE were consistently detected in all water and sludge samples, with THM emerging as the most abundant compound in both influent and effluent. Among the 3 WWTPs, WWTP 2, employing a fine bubble oxidation process, achieved the highest removal efficiency, surpassing 68%, in contrast to WWTP 1 (CAST) at 37% and WWTP 3 (A/A/O) at 7%. Biodegradation played a pivotal role in NEO removal, accounting for 36.7% and 68.2% of the total removal in WWTP 1 and WWTP 2, respectively. Surprisingly, in WWTP 3, biotransformation process inadvertently increased ACE and CLO concentrations by approximately 4.1% and 4.5%, respectively. The total NEO concentration in the receiving surface waters ranged from 72.7 to 155.5 ng/L, while sediment concentrations were significantly lower, spanning between 0.10 and 1.53 ng/g. WWTPs serve as both a removal and concentration point for NEOs, thereby significantly influencing their transportation. Additionally, the concentration of most NEOs in the receiving waters progressively increased from upstream to downstream, highlighting the substantial impact of WWTP discharges on natural water environments. This research offers valuable insights into NEO pollution surrounding WWTPs in the Pearl River Delta, ultimately aiding in pollution control and environmental protection decisions.

Temporary atmospheres produced by human activities on the Moon

Outgassing from materials, whether through the ascent/descent stages of lunar vehicles, airlock depressurizing, rover or astronaut suit outgassing, may cause an effect of unwanted accumulation of volatiles at the surface and exosphere. This is especially important at (or proximal) to permanently shadowed regions (PSRs) at the lunar poles. Herein, we provide estimates of expected outgassing from various human-landed objects on the Moon, including backpacks, airlocks, rovers, landers, trash and mining operations. Astronaut suits produce some level of oxygen outgassing (Helou et al., 2022), which may transport and condense in these PSRs, even in micro- cold traps (Glavin et al., 2010).We estimate the outgassing from drill mining and trash-to-gas conversion assuming a specific technology is operating. These outgassing systems can create local, temporary atmospheres in the vicinity (∼100 km radius) of the sources. The atmosphere may be particularly high within meters of the source. To obtain column densities for these temporary atmospheres, we first bracket ranges for the gas number loss as a function of time. We then derive the maximum distance traveled and the time the released molecules remain in the exosphere for a single ballistic hop, assuming the molecules are ejected from the surface of the object at its surface temperature. In some cases, such as the astronaut backpack and the rover, the temperature is that of the source. Given this information, an average and peak local exospheric density and column density can be estimated. We find that backpacks, airlock releases, and the Starship lander can create relatively high-density local atmospheres, with local near-lander outgassing water densities exceeding 107/cm3. This local water exosphere is over 106 times greater than the LADEE-derived lower limit of the natural water exosphere at ∼3/cm3. Thus, the anthropogenic temporary water exosphere will likely dominate the environment near the lander, making an assessment of the natural exospheric water environment difficult.

Zwitterionic functionalized chitosan with dual-antifouling for selective uranium extraction

Uranium adsorbents deployed in natural water environments rich in microorganisms for a long time are inevitably affected. Biofouling severely reduces the uranium adsorption performance and damages the structure of the adsorbents. Therefore, antifouling performance is necessary for adsorbents that extract uranium from seawater and uranium-containing groundwater. Previously reported antifouling uranium adsorbents mainly have two types: single antibacterial or anti-adhesion, and few studies have developed dual-antifouling adsorbents that combine the two antifouling pathways. In this study, a dual-antifouling adsorbent CS-MPC with both anti-adhesion and antibacterial properties was constructed. The synergistic effect of the superhydrophilic 2-methylacryloxyethyl phosphocholine (MPC) and the natural bactericidal chitosan (CS) enabled the inhibition rate of dual-antifouling CS-MPC against various bacteria to exceed 99 %. Furthermore, the uranium adsorption capacity of CS-MPC was 579 mg/g in simulated uranium-containing groundwater and 8.28 mg/g after immersion for 42 days in real seawater. The SA/CS-MPC composite beads prepared to solve powder defects also exhibited good dual-antifouling activity and uranium adsorption properties, making them potential candidates for uranium extraction. The construction of dual-antifouling adsorbents provides a new strategy for effective biofouling control.

Microplastic detection and remediation through efficient interfacial solar evaporation for immaculate water production

Freshwater scarcity and microplastics (MPs) pollution are two concerning and intertwined global challenges. In this work, we propose a “one stone kills two birds” strategy by employing an interfacial solar evaporation platform (ISEP) combined with a MPs adsorbent. This strategy aims to produce clean water and simultaneously enhance MPs removal. Unlike traditional predecessors, our ISEP generates condensed water free from MPs contamination. Additionally, the photothermally driven interfacial separation process significantly improves the MPs removal performance. We observed a removal ratio increase of up to 5.5 times compared to previously reported MPs adsorbents. Thus, our rationally-designed ISEP holds promising potential to not only mitigate the existing water scarcity issue but also remediate MPs pollution in natural water environments.

An Improved YOLOv8n Used for Fish Detection in Natural Water Environments.

To improve detection efficiency and reduce cost consumption in fishery surveys, target detection methods based on computer vision have become a new method for fishery resource surveys. However, the specialty and complexity of underwater photography result in low detection accuracy, limiting its use in fishery resource surveys. To solve these problems, this study proposed an accurate method named BSSFISH-YOLOv8 for fish detection in natural underwater environments. First, replacing the original convolutional module with the SPD-Conv module allows the model to lose less fine-grained information. Next, the backbone network is supplemented with a dynamic sparse attention technique, BiFormer, which enhances the model's attention to crucial information in the input features while also optimizing detection efficiency. Finally, adding a 160 × 160 small target detection layer (STDL) improves sensitivity for smaller targets. The model scored 88.3% and 58.3% in the two indicators of mAP@50 and mAP@50:95, respectively, which is 2.0% and 3.3% higher than the YOLOv8n model. The results of this research can be applied to fishery resource surveys, reducing measurement costs, improving detection efficiency, and bringing environmental and economic benefits.

Effective Removal of Pb(II) from Multiple Cationic Heavy Metals—An Inexpensive Lignin-Modified Attapulgite

To develop cost-effective heavy metal adsorbents, we employed water-soluble lignin from black liquor to modify activated attapulgite, resulting in the creation of a novel adsorbent called Lignin-modified attapulgite (LATP). In this study, scanning electron microscopy and Fourier transform infrared spectrometer techniques were utilized to characterize the structural details of LATP. The results revealed that lignin occupies the micropores of attapulgite, while additional functional groups are present on the attapulgite surface. We conducted adsorption tests using LATP to remove five types of heavy metal ions (Cd2+, Pb2+, Zn2+, Mn2+, Cu2+), and it was found that LATP exhibited greater removal mass and binding strength for Pb(II) compared to the other ions. For further investigation, batch experiments were performed to evaluate the adsorptive kinetics, isotherms, and thermodynamics of Pb2+ removal from aqueous solutions using LATP. The results indicated that the adsorption capacity of Pb(II) on LATP decreased with decreasing pH, while the presence of Na+ had no effect on adsorption. The adsorption process reached equilibrium rapidly, and the Langmuir adsorption capacities increased with temperature, measuring 286.40 mg/g, 315.51 mg/g, and 349.70 mg/g at 298 K, 308 K, and 318 K, respectively. Thermodynamic analysis revealed positive values for ΔH0 and ΔS0, indicating an endothermic and spontaneous adsorption process. Furthermore, ΔG0 exhibited negative values, confirming the spontaneous nature of the adsorption. Consequently, LATP demonstrates great potential as an effective adsorbent for the removal of Pb(II). Therefore, LATP shows great potential as an effective adsorbent for the removal of Pb(II) from natural water environments, contributing to the sustainable development of man and nature.

Elucidating the photodegradation mechanism of octylisothiazolinone and dichlorooctylisothiazolinone in surface water: An in-depth comprehensive analysis

Octylisothiazolinone (OIT) and Dichlorooctylisothiazolinone (DCOIT), widely used antibacterial agents in coatings, have seen a sharp increase in use in response to the Coronavirus disease 2019 (Covid-19) pandemic, ultimately leading to their increase in the aquatic environment. However, their photodegradation process in surface water is still unclear. The purpose of this study is to investigate the photodegradation kinetics and mechanisms of OIT and DCOIT in natural water environments. Under simulated solar irradiation, they undergo direct photolysis in both natural freshwater and seawater mainly via their excited singlet states, while no self-sensitization photolysis was observed. The direct photolysis rate constants of OIT and DCOIT were 1.19 ± 0.07 and 0.57 ± 0.03 h−1, respectively. In addition, dissolved organic matter (DOM), NO3− and Cl− in natural waters did not contribute significantly to the photodegradation, and the light screening effect of DOM was identified as the main inhibiting factor. The photodegradation half-life of OIT was estimated to be 0.66 to 1.69 days, while the half-life of DCOIT was as high as 20.9 days during winter in surface water at 30°N latitude. Ring opening of the N-S bond and covalent bond breaking between CN are the main pathways for the photodegradation of OIT and DCOIT, which is verified by density-functional theory calculations. Ecological Structure Activity Relationships (ECOSAR) results indicate that OIT and DCOIT have “Very Toxic” biological toxicity, and the acute toxicity of their products is significantly reduced. It is noteworthy that the toxicity of the products of DCOIT is generally higher than that of OIT, and the chronic toxicity of most of the products is still above the “Toxic” level. Therefore, an in-depth understanding of the photodegradation mechanisms of OIT and DCOIT in aqueous environments is crucial for accurately assessing their ecological risks in natural water environments.

A molecularly imprinted electrochemical aptasensor-based dual recognition elements for selective detection of dexamethasone

In this work, a novel molecularly imprinted electrochemical aptasensor (MIEAS) was developed for highly selective detection of dexamethasone (Dex) in natural water environment. Gold nanoparticles (AuNPs) modified by nitrogen doped molybdenum carbide-graphene (N–Mo2C-Gr) were employed as the supports, where N–Mo2C-Gr improved the conductivity of the electrode and provided a larger specific surface area to polymerize more active substances. Using Dex as template molecule, o-phenylenediamine (o-PD) as the chemical functional monomer and aptamer as the biofunctional monomer, a molecularly imprinted polymer (MIP) membrane with Dex specific recognition sites was formed by electropolymerization. Due to the synergistic effect of MIP and aptamers, the as-prepared MIEAS exhibited a decent linear relationship to Dex detection within a relatively wide range of 10−13 – 10−5 M, and the detection limit was 1.79 × 10−14 M. The recovery in actual water and tablet samples is satisfactory, which confirms the potential application prospects of this sensor in the determination of Dex.

Exploring mass transfer mechanisms in reverse osmosis membranes: A comparative study of SDM and DSPM-DE models

Thin-film composite reverse osmosis (RO) membranes have dominated desalination technology for decades, with the solution diffusion model (SDM) serving as the gold standard for interpreting mass transfer phenomena since its inception. However, debates still persist regarding the effect of charge on separation performance, owing to the SDM's inability to explore membrane charge. In this study, polyethyleneimine (PEI) was utilized to modify the surface of a commercial seawater desalination membrane (SW30, Dupont Company), imparting regulatable charge properties based on the solution pH. The separation performance of the modified RO membrane was experimentally validated under varying NaCl feed salinities. Specifically, the Donnan-steric pore model with dielectric exclusion (DSPM-DE), known as a charge-responsive model, was employed and juxtaposed with SDM to authenticate the experimental findings. The results indicated that the dielectric effect primarily governed ion distribution (Na+ and Cl−) within the membrane, followed by the steric effect, and ultimately, the Donnan effect. Consequently, DSPM-DE aligned well with the observed salt rejection only when the membrane was strongly charged (that is, under acidic or alkaline conditions), but performed poorly in the neutral state. This observation, rarely revealed in previous research, stems from conventional desalination membranes being negatively charged in most natural water environments. Conversely, the SDM aligned well with the experimental data because it solely considered the solutes' solubility parameters and diffusion coefficient, independently of the surface charge of the desalination membranes. Given the extensive research on surface modification, our study demonstrates the limited influence of charge effects on the selective enhancement of RO membranes.

Nanohybrid layered clay composite decorated with polyaniline for intensified Cr(VI) removal through enhanced Cr(VI) reduction

Hexavalent chromium (Cr(VI)) is mainly detected as a harmful anion in aquatic ecosystems. In this study, a novel nanohybrid layered clay composite decorated with polyaniline (PANI) (PANI/LDH@MMt) was successfully synthesized by a layer-by-layer assembly strategy and utilized for Cr(VI) removal. Layered double hydroxide (LDH) and montmorillonite (MMt) in nanohybrid layered clay (LDH@MMt) can facilitate Cr(VI) elimination through reinforced Cr(VI) reduction. Some key experimental parameters were evaluated in detail for their potential impact on Cr(VI) removal. The experimental results illustrated that PANI/LDH@MMt displayed high Cr(VI) removal efficiency (>99 %) at most appropriate conditions and maintained over 95 % performance even in ionic coexistence and natural water environments. Kinetic models, isothermal models, and thermodynamic analyses were also employed to explore the Cr(VI) removal behavior on PANI/LDH@MMt. Finally, the mechanism analysis suggested that Cr(VI) could be captured by electrostatic interaction of -NH-+, -N=+, and –OH2+, and anion exchange of LDH, and reduced to Cr(III) by -NH-. Subsequently, Cr(III) could chelate with -N=, −NH−, and −OH, complex with OH-, and be immobilized by MMt through cation exchange. This study presents a new insight into the reasonable construction of highly efficient adsorbents with low cost for Cr(VI) removal.

Effect of interactions between humic acid and cerium oxide nanoparticles on the toxicity to the Chlorella sp.

With the wide application of nanomaterials, the concentration of nanomaterials in natural water continues to increase, which poses a severe threat to the water environment. However, the influence of organic matter and nanomaterials rich in natural water on the toxic effect of algae growth is still unclear. In this study, the effects of humic acid (HA) and nano-cerium oxide (nCeO2) on the physiology and transcriptome of Chlorella sp. were analyzed, and the mechanism of the toxic effect of HA on Chlorella sp. under nCeO2 stress was revealed. Under 20-200 mg/L nCeO2 stress, the growth of Chlorella cells was inhibited and the highest inhibition rate reached 52% within 200 mg/L nCeO2. The Fv/Fm and ETRmax values of Chlorella sp. decreased from 0.490 and 24.45 (20 mg/L nCeO2) to 0.488 and 23.4 (100 mg/L nCeO2), respectively. Under the stimulation of nCeO2, the level of reactive oxygen species in algal cells was increased, accompanied by lipid peroxidation and membrane damage. However, the addition of HA at concentrations of 5-10 mg/L effectively alleviated the toxic effect of nCeO2 on Chlorella sp. Transcriptome analysis showed that 10 mg/L HA could alleviate the cellular stress at 100 mg/L nCeO2 on Chlorella sp. by regulating genes related to photosynthesis and metabolism pathways. Moreover, the downregulation of genes (e.g., Lhca1, Lhcb1, AOC3, and AOC2) indicated that HA reduced the level of oxidative stress in Chlorella sp. These findings offer novel insights of evaluating the ecotoxicity nCeO2 and HA in natural water environment and their impact on Chlorella sp.

Ubiquitous nanocolloids suppress the conjugative transfer of plasmid-mediated antibiotic resistance in aqueous environment

Nanocolloids (Nc) are widespread in natural water environment, whereas the potential effects of Nc on dissemination of antibiotic resistance remain largely unknown. In this study, Nc collected from the Yellow River in Henan province was tested for its ability to influence the conjugative transfer of resistant plasmid in aqueous environment. The results revealed that the conjugative transfer of RP4 plasmid between Escherichia coli was down-regulated by 52%–91% upon exposure to 1–10 mg/L Nc and the reduction became constant when the dose became higher (20−200 mg/L). Despite the exposure of Nc activated the anti-oxidation and SOS response in bacteria through up-regulating genes involved in glutathione biosynthesis and DNA recombination, the inhibition on the synthesis and secretion of extracellular polysaccharide induced the prevention of cell-cell contact, leading to the reduction of plasmid transfer. This was evidenced by the decreased bacterial adhesion and lowered levels of genes and metabolites relevant to transmembrane transport and D-glucose phosphorylation, as clarified in phenotypic, transcriptomics and metabolomics analysis of E. coli. The significant down-regulation of glycolysis/gluconeogenesis and TCA cycle was associated with the shortage of ATP induced by Nc. The up-regulation of global regulatory genes (korA and trbA) and the reduction of plasmid genes (trfAp, trbBp, and traG) expression also contributed to the suppressed conjugation of RP4 plasmid. The obtained findings remind that the role of ubiquitous colloidal particles is nonnegligible when practically and comprehensively assessing the risk of antibiotic resistance in the environment.

Abnormal eyes and spine development in zebrafish (Danio rerio) embryos and larvae induced by triphenyltin

Triphenyltin (TPT) is widely used in crop pest control and ship antifouling coatings, which leads to its entry into aquatic environment and poses a threat to aquatic organisms. However, the effects of TPT on the early life stages of wild fish in natural water environments remains unclear. The aim of this study was to assess the toxic effects of TPT on the early life stages of fish under two different environments: field investigation and laboratory experiment. The occurrence of deformities in wild fish embryos and larvae in the Three Gorges Reservoir (TGR) and the developmental toxicity of TPT at different concentrations (0, 0.15, 1.5 and 15 μg Sn/L) to zebrafish embryos and larvae were observed. The results showed that TPT content was higher in wild larvae, reaching 27.21 ng Sn/g w, and the malformation of wild fish larvae mainly occurred in the eyes and spine under natural water environment. Controlled experiment exposure of zebrafish larvae to TPT also resulted in eye and spinal deformities. Gene expression analysis showed that compared with the control group, the expression levels of genes related to eye development (sox2, otx2, stra6 and rx1) and spine development (sox9a and bmp2b) were significantly up-regulated in the 15 μg Sn/L exposure group, which may be the main cause of eye and spine deformity in the early development stage of fish. In addition, the molecular docking results further elucidate that the strong hydrophobic and electrostatic interactions between TPT and protein residues are the main mechanism of TPT induced abnormal gene expression. Based on these results, it can be inferred that TPT is one of the teratogenic factors of abnormal eye and spine development in the early life stage of fish in the TGR. These findings have important implications for understanding the toxicity of TPT on fish.

EVALUATION OF THE CARBON FOOTPRINT IN THE TREATMENT OF URBAN WASTEWATER IN THE CANARY ISLANDS (SPAIN)

ABSTRACT: Wastewater treatment plants play an important role within the urban water cycle to prevent the natural water environment and human health from being negatively affected by human activities. However, wastewater treatment processes, such as effluent discharge and indirect emissions resulting from energy or chemical production, also negatively affect the environment. Footprints have been used to track human influence on the environment in different areas of interest and have been applied to assess the sustainability of wastewater treatment plants. In this article, a comprehensive review of footprint assessment was investigated to evaluate the wastewater treatment process in wastewater treatment plants. The review showed that carbon footprinting was used to assess the sustainability of WWTPs, and that other footprint assessment applications (such as nitrogen and phosphorus footprinting) were also introduced to assess eutrophication of water bodies. To promote the application of footprint assessment, this article regulates the study objectives, frameworks, system boundaries, data processing methods, and the resulting interpretation process. The pros and cons of the footprint assessments were discussed and investigated in detail, examining the CO2 production on each island of the Canary archipelago, and several suggestions were proposed to improve the footprint assessments. Analysis of footprint assessments at different wastewater treatment plants revealed that wastewater treatment technologies and scales had a significant impact on footprints. Furthermore, research hotspots identified using a keyword network diagram showed that the water-carbon-energy nexus was a promising direction for future studies. The purpose of the study is to improve the reduction of the carbon footprint both at the level of direct and indirect emissions factors using new tools and methodologies. Key Words: Footprint; Waste water; Canary Islands