Aquatic Pollution Research Articles

Adsorption of the emerging pollutants on Buena Vista landfill cover material and implications on regional aquatic pollution

The occurrence of emerging pollutants in water represents a health risk for humans and the ecosystem. It has been shown that pollutant–soil interactions are determinants in preventing contamination of water sources by leachates from landfills. In this work, batch experiments were conducted to study the soil sorption process of amoxicillin (AMX), acetaminophen (ACP), levonorgestrel (LNG), and chlorothalonil (CTL) in four different soil layers used as cover material in Buena Vista landfill located in the municipality of La Union (Antioquia, Colombia). All soil layers were characterized using FT-IR, XRF and BET experimental techniques. In addition, pH and ionic strength effects on the adsorption process were also evaluated. The % of removal follows the order CTL > LNG > AMX > ACP in all soil layers. ACP y AMX adsorption was best described by pseudo-second-order kinetics, while LNG and CTL adsorption was best fitted by the pseudo-first-order kinetic model. Pollutant adsorptions were found to be favored at pH 6.3. Increasing the solution ionic strength decreases the adsorption of pollutants in all evaluated soil layers. The adsorption process was governed by hydrophilic and hydrophobic interactions. Polar molecules such as AMX and ACP remain in the aqueous phase while nonpolar LNG and CTL interact with clay minerals in the soil surface, presumably through van der Waals forces. Based on our findings, a cover material with both hydrophilic and lipophilic characteristics operating close to neutral, and with low ionic content, is advised for the Buena Vista landfill to improve its role as a barrier in decreasing potential pollutants contaminating groundwater sources.

Aquatic Microplastic Pollution Control Strategies: Sustainable Degradation Techniques, Resource Recovery, and Recommendations for Bangladesh

Microplastics’ dangers and the absence of effective regulation technologies have risen to prominence as a worldwide issue in recent years. South Asian countries, such as Bangladesh, are among the most threatened nations to face the drastic consequence of releasing microplastics into the aquatic environment. The research on managing and degrading microplastics is ongoing, however, sustainable techniques have not yet been found. To create a green and efficient microplastic management plan, we have compiled all the information on the existing removal and degradation techniques for microplastics and provided an overview of all the noteworthy methods that can be implemented in Bangladesh. In the portrayed biotic and abiotic techniques, coagulation and photocatalysis were found to be most efficient in removing microplastics (as high as 99%) in different studies. The concept of microplastic is new to the researchers of Bangladesh, therefore, the characteristics, occurrence, fate, and threats are briefly discussed in this paper. Sampling, extraction, and identification methods of microplastic in freshwater and sediment samples are also thoroughly specified. The sources of microplastic pollution in Bangladesh and possible strategies that can be implemented to minimize additional microplastic discharge into aquatic environments are discussed. Although Bangladesh was the very first country to ban polythene, the failure of the implementation of rules and regulations and a lack of management strategy made Bangladesh the 10th worst country in managing plastic waste. This work is a wake-up call for other researchers to conduct an in-depth investigation to improve microplastic degrading technologies and develop a sustainable strategy to end microplastic pollution in Bangladesh.

Preface

To begin with, we would like to express our deepest gratitude to all committees for the success and smooth running of the International Marine and Fisheries Symposium (ISMF). And it is with a great honour; we present the proceedings of the 5th International Marine and Fisheries Symposium (ISMF) which was organized by Faculty of Marine Science and Fisheries, Universitas Hasanuddin collaborated with Universiti Malaysia Terengganu and held hybrid in the 4-5 of June 2022. The Proceedings of the previous conferences in this series have been published in the IOP conference series: Earth and Environmental Science (EES).The world countries have adopted the global Sustainable Development Goals (SDGs) action agenda. Among these seventeen (17) goals, Goal 14 on Life Below Water is intrinsically linked to the marine and fisheries sector. Efforts to achieve SDGs targets and to save our aquatic environments require full attention and support, especially to address the acute pressures and threats to the environment that increase in time. Thus, the theme of the 5th ISMF is “Advancing marine and fisheries sectors to achieve the Sustainable Development Goals (DSGs) for healthy aquatic environments and society”The 5th International Marine and Fisheries Symposium (ISMF) has a broad of topics including Aquatic Biodiversity, Aquatic Ecology and Conservation, Oceanography, Marine and Fisheries Biotechnology, Sustainable Aquaculture, Marine and Fisheries Geographic Information System, Aquatic Pollution and Ecotoxicology and Natural Disaster Mitigation and AdaptationThe proceeding of the 5th ISMF 2022 consists of 115 reviewed papers. In addition to the excellent paper presentations at the conference, the conference also featured eleven keynote and invited speakers with expertise in the field of the conference’s subjects. Please allow us to take this opportunity to thank the keynote speaker and the invited speakers: Ir. Sakti Wahyu Trenggono, M.M, H A. Muchtar Ali Yusuf, H. Muh. Yusran Lalogau, S.Pi., M.Si., Dr. Ing. Widodo Setiyo Pranowo, M.Si., Prof. Dr. Rajuddin Syamsuddin, M.Sc., Prof. Harry Palm, Dr. Mukti Zainuddin, M. Sc, Dr. Nurul Ulfah Karim, Davin H. E. Setiamarga, Ph.D., Dr. Ana Isabel Sousa, and Dr. Amanda R. Lindsay.A warm thank you to all academics, researchers and observers of the marine and fisheries sector for their participation to submit article in the proceeding of 2022 Universitas Hasanuddin Marine and Fisheries Symposium. It is my sincere hope that all the contributions made will be of benefit and promote the development of the marine and fisheries sector towards the achievement of the SDGs, especially SDG-14.Warm Regards,Dr. Ir. Siti Aslamyah, MPConference ChairwomanFaculty of Marine Science and Fisheries, Universitas HasanuddinList of Conference Committees are available in this pdf.

Synthesis of MIL-125/NTU-9 Heterojunction MOF for Photocatalytic Removal of Aquatic Pollutants

Synthesis of MIL-125/NTU-9 Heterojunction MOF for Photocatalytic Removal of Aquatic Pollutants

A Study on the Behavior Evaluation and Control of Midge Larvae in the Filtration Process

Recently, midge larvae, which are indicators of aquatic environmental pollution, have been detected in tap water in some areas, resulting in controversy. Therefore, the objective of this study is to analyze the behavioural features of midge larvae in sand, GAC (granular activated carbon) and GAC/sand processes, which are mainly operated in domestic water purification plants, and suggest effective operating methods for larval control. In this study, a pilot-scale square column (W300×L300×H3500~5000 mm) was used for the filtration experiment and was used with a filter height of 2.5 m as well as in the field. The water to be treated was the sand filtered from the water purification plant G, and midge larvae from the Han River were injected periodically and operated for an estimated 40 to 50 days. As a result, no larvae were detected during the first five operational days in the sand filter and GAC and 14 days in the case of GAC/sand. However, after backwashing, larvae were detected from the 9th day of operation for sand and GAC, and from the 15th day for GAC/sand. In the case of sand laying under the GAC, larvae detection was delayed by approximately 6 days compared to the operation of the GAC alone. Following examination of larval distribution in relation to the height of the activated carbon layer after approximately 50 days of operation, it was found that the larvae were distributed on 17% in the upper layer, 7% in the middle layer, 19% in the lower layer and 0.2% in the lower water collection device. Therefore, it is necessary to shorten the backwashing cycle from the initial stage of larval introduction and to increase the rate of expansion of GAC during the backwashing to quickly flush out the larvae. The results of this study also confirmed that when the backwash speed was 0.57 m/min or more, the rate of expansion of GAC was 30% or more, and larval rejection increased approximately twice when compared with a washing rate of 0.45 m/min. Consequently, as a method of effective functioning of the filtration process for larval control, in the case of sand filtration, when it is difficult to expand the filter media, it is necessary to increase the rinsing time, and in the case of GAC, it is necessary to quickly discard the larvae by increasing the backwashing rate and shortening the backwashing cycle.

Magnetic Hydrogel Composite for Wastewater Treatment.

Nanocomposite hydrogels are highly porous colloidal structures with a high adsorption capacity, making them promising materials for wastewater treatment. In particular, magnetic nanoparticle (MNP) incorporated hydrogels are an excellent adsorbent for aquatic pollutants. An added advantage is that, with the application of an external magnetic field, magnetic hydrogels can be collected back from the wastewater system. However, magnetic hydrogels are quite brittle and structurally unstable under compact conditions such as in fixed-bed adsorption columns. To address this issue, this study demonstrates a unique hydrogel composite bead structure, providing a good adsorption capacity and superior compressive stress tolerance due to the presence of hollow cores within the beads. The gel beads contain alginate polymer as the matrix and MNP-decorated cellulose nanofibres (CNF) as the reinforcing agent. The MNPs within the gel provide active adsorption functionality, while CNF provide a good stress transfer phenomenon when the beads are under compressive stress. Their adsorption performance is evaluated in a red mud solution for pollutant adsorption. Composite gel beads have shown high performance in adsorbing metal (aluminium, potassium, selenium, sodium, and vanadium) and non-metal (sulphur) contaminations. This novel hybrid hydrogel could be a promising alternative to the conventionally used toxic adsorbent, providing environmentally friendly operational benefits.

Adsorption of sulfonamides on polyamide microplastics in an aqueous solution: behavior, structural effects, and its mechanism

Although microplastics (MPs) and sulfonamides (SAs) are emerging aquatic pollutants, the structural effects of SAs following their adsorption on MPs and underlying mechanisms of the same remain unelucidated. In this study, the characteristics of the adsorption of 10 SAs on polyamide (PA) were analyzed, and significant structural effects of the former were observed at different pH values (P < 0.01). The highest adsorption distribution coefficient (Kd) was ∼7.83–43.57 times the lowest one. The key processes and micromechanisms of SA adsorption on PA were revealed using the quantitative structure–activity relationship model and partial least squares structural equation model (PLS-SEM). The results suggest that both the octanol–water partition coefficients (Kow) of SAs and the valid adsorption energies (Ead-v) between PA and SAs are vital in the observed structural effects of SAs. Furthermore, the density functional theory results demonstrated that during the adsorption of SAs on PA, the different adsorption energies were engendered by equilibrium configurations and interactions, such as hydrophobic, hydrogen bond (H-bond), van der Waals, and electrostatic interactions. Moreover, the developed PLS-SEM models revealed that during the adsorption of cationic (PA–SA+) and anionic (PA–SA−) SAs, the structural effects were partially driven by the electrostatic interactions. Conversely, the structural effects of neutral SA (SA0) adsorption on PA were partially due to H-bond interactions. Overall, we pioneered a theoretical basis to understand the structural effects of SAs following their adsorption on MPs.

Quick sand filtration in restaurant waste treatment with coconut fiber and activated carbon media: application of Van der Waals Force

Domestic liquid waste has become the leading cause of aquatic pollution, with a percentage of 60-70%. One of the media that has the potential to process water is coco fibre. This study aimed to analyze the Effectiveness of both media in reducing restaurant waste. The experiment was conducted with variations in the Thickness of coco fibre and activated carbon media of 10, 15, and 20 cm and sand 40 mesh of 10 cm. The addition of sand media proved more effective in meeting quality standards with the Effectiveness of the reduction of Total Suspended Solid (TSS), Chemical oxygen demand (COD), and turbidity, the highest obtained at the Thickness of coco fibre media 20 cm activated carbon 20 cm, and sand 40 mesh 10 cm, which is respectively 95.78, 93.04, and 98.72%, which is influenced by the Thickness and time of contact of waste with the media.

A review of mechanism and adsorption capacities of biochar-based engineered composites for removing aquatic pollutants from contaminated water

Water contamination by aquatic pollutants (antibiotics, heavy metals, nutrients, and organic pollutants) has become the most serious issue of recent times due to associated human health risks. Biochar (BC) has been deemed an effective and promising green material for the remediation of a wide range of environmental pollutants. Due to its limited properties (small pore size and low surface functionality), pristine BC has encountered bottlenecks in decontamination applications. These limitations can be rectified by modifying the pristine BC into engineered BC via multiple modification methods (physical, chemical, and mechanical), thus improving its decontamination functionalities. Recently, these engineered BCs/BC-based composites or BC composites have gathered pronounced attention for water decontamination due to fewer chemical requirements, high energy efficiency, and pollutant removal capacity. BC-based composites are synthesized by mixing BC with various modifiers, including carbonaceous material, clay minerals, metals, and metal oxides. They considerably modify the physiochemical attributes of BC and increase its adsorption ability against various types of aquatic pollutants. BC-based composites are efficient in eliminating target pollutants. The efficiency and type of a specific mechanism depend on various factors, mainly on the physicochemical characteristics and composition of the BC-based composites and the target pollutants. Among the different engineered BCs, the efficiency of clay-BC composites in removing the antibiotics, dyes, metals, and nutrients was good. This review could help develop a comprehensive understanding of using engineered BCs as effective materials for the remediation of contaminated water. Finally, gaps and challenges in research are identified, and future research needs are proposed.

Chitosan—the miracle biomaterial as detection and diminishing mediating agent for heavy metal ions: A mini review

Proliferation of heavy metal ions as aquatic pollutants has been a matter of growing concern now a days. Several anthropogenic activities have fueled higher concentration of heavy metal ions in aquatic bodies above threshold values, as set by World Health Organization. Of late, chitosan for its exquisite properties has been widely used in tackling this burning problem of aquatic pollution caused by heavy metal ions. Accordingly, this mini review appraises the detection as well as diminution activities where chitosan plays the major contributing part. Starting from the intrinsic properties of chitosan, the detection strategy via chitosan composites is comprehensively delineated. Likewise, the removal activities via chitosan mediating agents are also overviewed, followed by future recommendations. It is believed that this mini review will give researchers a brief appraisal of two prominent activities related to controlling of heavy metal ion pollution.

Immune-antioxidant trait, growth, splenic cytokines expression, apoptosis, and histopathological alterations of Oreochromis niloticus exposed to sub-lethal copper toxicity and fed thyme and/or basil essential oils enriched diets

Two experiments were conducted in this study, using 250 Oreochromis niloticus (O. niloticus) (average weight 30.28 ± 0.27 g). The first experiment was conducted to investigate the 96-h lethal concentration 50 (LC50) of copper chloride (CuCl2) using the probit analysis, seventy fish was divided into seven different concentration of CuCl2 (0, 22, 23, 24, 25, 26, and 27 mg/L), the accurate Cu concentrations were (1.23, 5.36, 6.02, 6.98, 7.05, 7.93, 8.12 mg/L Cu). The second experiment was conducted for investigating the effect of dietary supplementation with thyme (Thymus vulgaris, T. vulgaris) and sweet basil (Ocimum basilicum, O. basilicum) essential oils (TEO and BEO respectively) against sub-lethal Cu exposure (1/10 96-h LC50 of CuCl2). About 180 fish was divided into six groups in triplicate (10 fish/replicate, 30 fish/group). Group 1 (C) was kept as a control group with no Cu exposure and was fed the control basal diet. Group 2 (C–Cu) was fed the control basal diet and simultaneously exposed to 1/10 of the 96 h LC50 of CuCl2 (2.574 mg/L) as a sub-lethal concentration of Cu, where the realistic Cu concentration was 3.976 mg/L. Group 3 (TEO) and group 4 (BEO) were fed the diets fortified with 1%TEO and BEO, respectively without exposure to Cu. Group 5 (TEO-Cu) and group 6 (BEO-Cu) were fed the diets fortified with 1%TEO and 1%BEO, respectively, and simultaneously exposed to 1/10 of the 96 h LC50 of CuCl2 (2.574 mg/L). The growth and behavioral performance, immunological response and its related gene expression, antioxidant status, stress biomarker indicators, apoptosis biomarkers, and histopathological alteration were investigated. The results of the first experiment showed that the 96-h LC50 of CuCl2 in O. niloticus was 25.740 mg/L with lower and upper confidence limits of 25.152 and 26.356 mg/L, respectively. The results of the second experiment showed that sub-lethal Cu exposure induced growth retardation (lowered final body weight, total weight gain, and specific growth rate %), behavioral abnormalities (slower swimming activity and feeding performance), immunosuppression (lowered nitric oxide, complement-3, lysozyme, total proteins, albumin, and globulin), and lowering the hepatic antioxidant functions (higher MDA, and lower SOD, CAT, and GPx) in the exposed fish. Furthermore, alteration in the immune-related genes expression (down-regulation of IL-10 and TGF-β and up-regulation of IL-1β, IL-6, IL-8, and TRL-4), hepato-renal dysfunction (elevated ALT, AST, urea, and creatinine), and high levels of serum stress indicators (cortisol and glucose) were markedly evident. sub-lethal Cu toxicity induced significant up-regulation of apoptosis biomarkers involving, nuclear factor-κβ (NF-κβ), Bcl-2 Associated X-protein (BAX), meanwhile, the expression of B-cell lymphoma 2 (BCL2) and Proliferating cell nuclear antigen (PCNA) was remarkably down-regulated. In addition, apoptosis was also evident by histopathological investigation of branchial, hepatic, and renal sections. TEO and/or BEO dietary supplementation mitigate the destructive impacts of sub-lethal Cu exposure in O. niloticus, depending on the results of our study, it could be concluded that TEO and BEO with a 1% dietary level could be a promising antioxidant, immunostimulant, anti-stress factors, and anti-apoptosis mediators against heavy metal contaminants (Cu) in O. niloticus, providing a solution to the problem of aquatic bodies pollution, consequently aiding in the development of aquaculture industry.

Expression of genes related to antioxidation, immunity, and heat stress in Gambusia affinis exposed to the heavy metals Cu and Zn

Water pollution is an increasingly serious problem. Here, Cu and Zn ions were used as stress factors, and G. affinis served as a test organism. Fluorescence quantitative PCR was used to detect changes in the expression of antioxidant genes (SOD, GST, CAT), heat stress genes (Hsp70, Hsp90, Hspd1, Hsc70), and immune system-related genes (IL-1β, IL-8) in G. affinis exposed to Cu and Zn ions over time. To explore the toxic effects of Cu and Zn on G. affinis. The results showed that the 48 h LC50 concentrations of the heavy metals Cu and Zn to G. affinis were 0.17 mg/L and 44.67 mg/L, respectively. Within 48 h, with prolonged Cu exposure, the relative expression levels of the Hsp70, Hsp90, Hspd1, Hsc70, SOD, GST, and CAT genes in the gill tissue first showed a significant increase and then gradually decreased. Gene expression peaked between 9 and 36 h. The relative expression levels of SOD and GST genes in liver tissue showed a gradual decline. Within 48 h, with prolonged Zn exposure, the expression levels of SOD, CAT, and GST genes in G. affinis first increased and then fell before finally rising. The expression levels of IL-1β and IL-8 mRNA showed varying degrees of upward trends, and the expression of IL-8 was the highest for all gill tissue. To sum up, Cu and Zn have strong toxic effects on G. affinis, which makes it possible to use G. affinis as indicator organisms for aquatic environmental pollution.

Assessment of water quality index and some oxidative stress biomarkers in Labeo rohita as the indicator of aquatic pollution in different ponds of Malda, West Bengal, India

Assessment of water quality index and some oxidative stress biomarkers in Labeo rohita as the indicator of aquatic pollution in different ponds of Malda, West Bengal, India

Efficient degradation of alkyl imidazole ionic liquids in simulated sunlight irradiated periodate system: Kinetics, reaction mechanisms, and toxicity evolution

As a class of emerging aquatic pollutants, alkylimidazole-based ionic liquids (AM-ILs) have received extensive attention due to the large acute toxicity to aquatic organisms. Therefore, in order to protect both aquatic organisms and human beings, it is necessary to seek an efficient and environmental-friendly technology for removal of AM-ILs from water bodies. In this work, we found that under simulated sunlight (Xe lamp) irradiation, periodate (KIO4, PI) could efficiently degrade 1-hexyl-2,3-dimethylimidazolium bromide ([HMMIm]Br), a representative AM-ILs with six carbon atoms in the side chain. Kinetics experiments on the degradation of [HMMIm]Br were performed, and the results showed that a high degradation efficiency (≥90.00%) of the cation ([HMMIm]+) was still maintained under harsh water conditions of strong acidity/alkaliny or with various non-target inorganic ions. More importantly, the anion of bromide ion (Br−) was not oxidized to the carcinogenic bromate (BrO3−) in current reaction system. The excited stated PI (marked as PI*) was detected by Laser flash photolysis, and it was an important reactive species for [HMMIm]+ degradation. As rationalized by theoretical calculations and scavenging experiments, the main oxidation mechanisms of [HMMIm]+ were hydroxyl radicals induced substitution reaction, PI* initiated electron and double oxygen transfer, and direct photolysis mediated chemical bond cleavage reaction, which contributed to 73%, 21%, and 6% of [HMMIm]+ degradation, respectively. Moreover, toxicity evaluation by ECOSAR software indicated that the oxidation products were generally less toxic to three aquatic organisms (fish, water flea, and green algae) than the target molecule [HMMIm]Br. In conclusion, this work proposed novel oxidation mechanisms of sunlight-activated PI system, and the findings may inspire further researches on the application of photoactivated hypervalent acids in water purification.

Seasonal drivers and risks of aquatic pesticide pollution in drought and post-drought conditions in three Mediterranean watersheds

The Western Cape in South Africa has a Mediterranean climate, which has in part led to an abundance of agriculturally productive land supporting the wheat, deciduous fruit, wine, and citrus industries. South Africa is the leading pesticide user in Sub-Saharan Africa. There is limited data on the pesticide pollution of surface water over different seasons in low- and middle-income countries. We evaluated the seasonal drivers of aquatic pesticide pollution in three river catchments (Berg, Krom, and Hex Rivers) from July 2017 to June 2018 and April to July 2019, using 48 passive samplers. Our sampling followed the most severe drought (2015–2018) since recordings in 1960. Thus, our analyses focus on how drought and post-drought conditions may affect in-stream pesticide concentrations and loads. Samples were analyzed for 101 pesticide compounds using liquid chromatography – high-resolution mass spectrometry. Environmental Quality Standards (EQS) were used to assess the risks. We detected 60 pesticide compounds across the sampling periods. Our results indicate that all samples across all three catchments contained at least three pesticides and that the majority (83%) contained five or more pesticides. Approximately half the number of pesticides were detected after the drought in 2018. High concentration sums of pesticides (>1 μg/L) were detected over long time periods in the Hex River Valley (22 weeks) and in Piketberg (four weeks). Terbuthylazine, imidacloprid, and metsulfuron-methyl were detected in the highest concentrations, making up most of the detected mass, and were frequently above EQS. The occurrence of some pesticides in water generally correlated with their application and rainfall events. However, those of imidacloprid and terbuthylazine did not, suggesting that non-rainfall-driven transport processes are important drivers of aquatic pesticide pollution. The implementation of specific, scientifically sound, mitigation measures against aquatic pesticide pollution would require comprehensive pesticide application data as well as a targeted study identifying sources and transport processes for environmentally persistent pesticides.

Remediation of Water Using a Nanofabricated Cellulose Membrane Embedded with Silver Nanoparticles.

The removal of pesticide pollution is imperative, because of their high environmental load and persistence, and their potential for bioaccumulation in, and toxicity to the environment. Most pesticides are found to be toxic even at trace levels. AgNPs can be effectively used for the adsorption of pesticides, and the incorporation of the AgNPs onto a support polymeric membrane enhances their effectiveness and reduces the potential unwanted consequences of intentionally adding free nanoparticles to the environment. Here, silver nanoparticles (AgNPs) were synthesized using a reliable, eco-friendly, and one-step "green" method, by reacting Mentha Piperita (mint) extract with AgNO3 aqueous solution at 60 °C in a microwave. The resulting high surface area nanoparticles are both economic and effective environmental remediation agents, playing a promising role in the elimination of aquatic pesticide pollution. Embedding the nanoparticles into a cellulose membrane at a low concentration (0.1 g) of AgNPs was shown to result in effectively adsorption of representative pesticides (Cypermethrin, Paraquat, and Cartap) within 60 min, while increasing the concentration of nanoparticles incorporated into the membrane further enhanced the removal of the exemplar pesticides from water. The high adsorption capacity makes the cellulose-AgNPs membrane an excellent substrate for the remediation of pesticide-polluted water.

Effect of dissolved organic matter on the bioavailability and toxicity of cadmium in zebrafish larvae: Determination based on toxicokinetic–toxicodynamic processes

The presence of dissolved organic matter (DOM) strongly influences the bioavailability of metals in aquatic environments; however, the association between the binding activities and the concentrations of DOM compositions is not well documented, leading to uncertainties in metal toxicity assessment. We creatively quantify the mitigation and acceleration effects of DOM compositions on cadmium (Cd) bioaccumulation and toxicity in zebrafish larvae using abiotic ligand (ABLs) and biotic ligand (BLs) in a toxicokinetic–toxicodynamic (TK–TD) model. The BL–TK–TD model could accurately predict the protective effect of fulvic acid while overestimating the complexing capacity of citric acid. The model also could successfully simulate the protective effects of native DOM in most cases from 32 natural water bodies in China. The observed LC50 values of Cd showed a peak effect for the native DOM fraction comprising hydrophilic acidic contents (3.55 ± 0.44 mg L − 1) in natural water from 32 sites. The BL–TK–TD model provides practically useful information to identify the effect of different DOM compositions on metal bioavailability and toxicity in aquatic environments and guides future water management policies aimed at controlling aquatic heavy metal pollution.

Synthesis of a novel visible-light active Gd2O3/GdVO4/V2O5 photocatalyst for rapid purification of industrial wastewater containing organic dyes and bacteria

In the past decades, population growth and industrial development have posed a significant threat to the aquatic environment and water pollution, considerably influencing our living standards. In the present study, novel visible light-responsive nano photocatalysts Gd2O3/GdVO4/V2O5 were synthesized by mechanical alloying and sintered at different elevated temperatures. All the structural and microstructural parameters of the mechanosynthesized C12.6N0.6VO3 phase have been modified from the reported values. XRD, TEM, SEM, XPS, and FTIR are employed to characterize the as-obtained nanocomposites with elemental mapping. The surface or grain boundary defects, bandgap, and Urbach energy of the nanocomposites are revealed by diffused reflectance spectroscopy (DRS) and BET analysis. The photodegradation and quantum efficiency of the samples are investigated by analyzing UV–Vis spectra, using Rhodamine B (RhB), Congo Red (CR), and Methylene Blue (MB) as model organic dye pollutants. Experimental results reflect that the 5 h milled and sintered sample shows better photocatalytic degradation efficiency of almost 100% within 150 min - nearly twice that of pure precursor materials. Scavenger tests ensure the oxidative radical species involved in the photodegradation mechanism. The antibacterial study reveals that the Gd2O3/GdVO4/V2O5 nanocomposite efficiently prohibits gram-positive bacterial growth in the wastewater. These Gd2O3 /GdVO4 /V2O5 nanocomposites may be utilized as an efficient tool for wastewater treatment in industrial areas and prohibiting bacterial growth in wastewater.

Phthalate esters and plastic debris abundance in the Red Sea and Sharm Obhur and their ecological risk level

The abundance of plastic debris (PDs) and its correlation with phthalic acid esters (PAEs), a class of pollutants associated with plastics, is not well understood, although PDs have been reported in relation to the release and distribution of aquatic pollutants such as PAEs. Few studies have linked the distribution of these pollutants in seawater. The current study examined the abundance and relationship of PDs and PAEs in seawater from Sharm Obhur and the Red Sea. Estimates were also made of their ecological impacts. Sharm Obhur is a semi-enclosed bay on the eastern shore of the Red Sea, near Jeddah, Saudi Arabia, and is heavily impacted by human activities. Contaminants from Sharm Obhur may be transported into the deep waters of the Red Sea by the subsurface outflow. The PAEs concentrations in the study area ranged from 0.8 to 1224 ng/L. Among the six PAEs studied, diethyl phthalate (DEP) (22–1124 ng/L), di-n-butyl phthalate (DBP) (9–346 ng/L) and di (2-ethylhexyl) phthalate (DEHP) (62–640 ng/L) were the predominant additives detected across all the sampling sits. Whereas the other PAEs, dimethyl phthalate (DMP) (5–76 ng/L), benzyl butyl phthalate (BBP) (4–25 ng/L) and di-n-octyl phthalate DnOp (0.5–80 ng/L) were generally lower in most samples. The sum of the six analyzed PAEs (∑6 PAEs) was lower at Sharm Obhur (587 ± 82 ng/L) and in the Red Sea shelf (677 ± 182 ng/L) compared to the Red Sea shelf break (1266 ± 354 ng/L). This suggests that degradation and adsorption of PAEs were higher in Sharm Obhur and on the shelf than on the shelf break. In contrast, there was no difference in the abundance of PDs between Sharm Obhur (0.04 ± 0.02 PDs/m3), Red Sea shelf (0.05 ± 0.02 PDs/m3) and in the Red Sea shelf break (0.03 ± 0.1 PDs/m3). Polyethylene (32%) and polypropylene (8%) were dominant, mostly smaller than 5 mm2 (78%), with the majority consisting of white (52%) and black (24%) fragments (39%), fibers (35%) and films (24%). A positive correlation between PAE concentration and abundance of PDs, suggests either a common source or a causal link through leaching. The ecological risk of ∑4PAEs (DMP, DEP, DBP and DEHP) ranged from (0.20–0.78), indicating a low to moderate risk for the Red Sea. The pollution index of PDs ranged from (0.14–0.36), showing that the Sharm Obhur and both sites of Red Sea suffered relatively low pollution.

Comparative behavioral ecotoxicology of Inland Silverside larvae exposed to pyrethroids across a salinity gradient

Pyrethroids, a class of commonly used insecticides, are frequently detected in aquatic environments, including estuaries. The influence that salinity has on organism physiology and the partitioning of hydrophobic chemicals, such as pyrethroids, has driven interest in how toxicity changes in saltwater compared to freshwater. Early life exposures in fish to pyrethroids cause toxicity at environmentally relevant concentrations, which can alter behavior. Behavior is a highly sensitive endpoint that influences overall organism fitness and can be used to detect toxicity of environmentally relevant concentrations of aquatic pollutants. Inland Silversides (Menidia beryllina), a commonly used euryhaline model fish species, were exposed from 5 days post fertilization (~1-day pre-hatch) for 96 h to six pyrethroids: bifenthrin, cyfluthrin, cyhalothrin, cypermethrin, esfenvalerate and permethrin. Exposures were conducted at three salinities relevant to brackish, estuarine habitat (0.5, 2, and 6 PSU) and across 3 concentrations, either 0.1, 1, 10, and/or 100 ng/L, plus a control. After exposure, Inland Silversides underwent a behavioral assay in which larval fish were subjected to a dark and light cycle stimuli to determine behavioral toxicity. Assessment of total distanced moved and thigmotaxis (wall hugging), used to measure hyper/hypoactivity and anxiety like behavior, respectively, demonstrate that even at the lowest concentration of 0.1 ng/L pyrethroids can induce behavioral changes at all salinities. We found that toxicity decreased as salinity increased for all pyrethroids except permethrin. Additionally, we found evidence to suggest that the relationship between log KOW and thigmotaxis is altered between the lower and highest salinities.