Comprehensive review on toxic heavy metals in the aquatic system: sources, identification, treatment strategies, and health risk assessment

Toxicological risk assessment and sources of heavy metal(loid)s using compositional data analysis, Astore River Basin, Himalaya

Himalayan rivers were observed to be more vulnerable having irregular water flows, flooding, and contamination due to various stresses, including climate change, urbanization, and industrial development. This study investigated the occurrence, sources, ecological, and health-based ramifications for heavy metal(loid)s (HM), i.e., As, Cu, Zn, Co, Pb, Sb, Cr, Cd, Mn, and Ni in the Astore river basin (ARB), Himalayas, Pakistan. Results of HM contamination index (HCI) estimations suggested that 2.43 %, 12.2 %, and 24.4 % of water samples from the Astore and Rupal valleys may pose strong, moderate, and low toxicity risks, respectively. Pb, Cu, and Cd contribute more to the aquatic toxicity than any other HM included in the ecological risk index (ERI) estimations. Children are the most vulnerable age group to health ailments caused by HM. Statistical analyses revealed that geogenic sources mainly contribute to HM, except for Ni and Cr, which are mainly derived from anthropic sources in ARB.

Application of online magnetic spray ionization mass spectrometry to risk assessment of metals and metalloids pollution in coastal waters and saline Inland Lakes in China

Data obtained via different methods for the same element in the same area significantly vary due to the interference from Ca2+ and Mg2+ matrices. In this study, 25 representative elements in the Bohai Sea, Yellow Sea, East China Sea, Beibu Gulf, Qinghai Lake and Chaka Salt Lake were investigated and classified via the newly developed online magnetic spray extraction-inductively coupled plasma-mass spectrometry (MSE-ICPMS) method, which can decrease the interference from Ca2+ and Mg2+ matrices. The ecological and health risks in these areas were subsequently assessed via the hazard index, hazard quotient, and ecological risk index. According to the ecological risk index analysis, the ecological risk levels in the Yellow Sea, Bohai Sea and Chaka Salt Lakes are relatively high. In addition, the concentrations presented in this study do not pose adverse health risks to the human body.

Accumulation of selected heavy metals in a sediment sample on the example of Lake Bagry (Poland): Modelling studies

The presence of heavy metals (HMs) in aquatic environments poses significant environmental risks due to their persistence, toxic properties, and potential for bioaccumulation in organisms. Their increased concentrations are found in many water bodies, especially post-mining lakes such as Bagry Lake in Cracow. This paper presents the modelling study on the adsorption of Cu, Pb, Zn, Cd, and Co in the bottom sediment of Bagry Lake, considering the temperature effect and the type of fraction (mineral and volatile). The HM concentrations from the clay-silty fraction (<0.06 mm) sediment were determined using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). HM content in water solutions was determined by Atomic Absorption Spectroscopy (AAS). The Freundlich model shows that the organic fraction has the highest sorption capacity, especially for Pb and Cd. In contrast, the mineral fraction had the lowest sorption efficiency, whereas the sorption was at an intermediate level for the mix of sediment fractions. A developed Thermodynamic Adsorption Model (TAM) has shown that HM accumulation processes can be either spontaneous or non-spontaneous, exothermic or endothermic, with temperature influencing sorption efficiency. This study enhances the understanding of HM accumulation dynamics in sediment systems and provides insights into environmental remediation strategies.

Fabrication of physically multi-crosslinked sodium alginate/carboxylated-chitosan/attapulgite-base aerogel modified by polyethyleneimine for the efficient adsorption of organic dye and Cu(II) contaminants

The simultaneous presence of heavy metal ions and organic dyes presents significant challenges for the wastewater treatment sector. In response to this pressing issue, a novel composite aerogel has been developed: polyethyleneimine-modified sodium alginate/carboxylated chitosan/attapulgite aerogels (ATP/CCS/SA-PEI), which effectively facilitates the concurrent removal of copper ions (Cu(II)), Congo red (CR), and methylene blue (MB) from aqueous solutions. Under optimal adsorption conditions, ATP/CCS/SA-PEI exhibits superior adsorption capacities for Cu(II), MB, and CR when compared to the unmodified raw materials at equivalent dosages, achieving maximum capacities of 228.24 mg/g for Cu(II), 206 mg/g for MB, and 290.13 mg/g for CR. Additionally, the presence of coexisting ions exerts a minor adverse effect on adsorption efficiency, indicating that the synthesized ATP/CCS/SA-PEI aerogels possess commendable environmental adaptability. Characterization techniques reveal that the primary mechanisms underlying adsorption involve electrostatic interactions, hydrogen bonding, coordination complex formation, and ion exchange synergies. Simultaneously, the ATP/CCS/SA-PEI aerogel exhibits significant reusability, retaining removal efficiencies of 53 % for MB and 48 % for Cu(II) after four sorption-desorption cycles. Consequently, the synthesized ATP/CCS/SA-PEI aerogel demonstrates considerable potential for the remediation of complex pollutants in wastewater, indicating its applicability across diverse industrial sectors.

The exposome and pancreatic cancer, lifestyle and environmental risk factors for PDAC

Pancreatic cancer (PC), particularly pancreatic ductal adenocarcinoma (PDAC), is a significant global health issue with high mortality rates. PDAC, though only 3 % of cancer diagnoses, causes 7 % of cancer deaths due to its severity and asymptomatic early stages. Risk factors include lifestyle choices, environmental exposures, and genetic predispositions. Conditions like new-onset type 2 diabetes and chronic pancreatitis also contribute significantly. Modifiable risk factors include smoking, alcohol consumption, non-alcoholic fatty pancreatic disease (NAFPD), and obesity. Smoking and heavy alcohol consumption increase PC risk, while NAFPD and obesity, particularly central adiposity, contribute through chronic inflammation and insulin resistance. Refined sugar and sugar-sweetened beverages (SSBs) are also linked to increased PC risk, especially among younger individuals. Hormonal treatments and medications like statins, aspirin, and metformin have mixed results on PC risk, with some showing protective effects. The gut microbiome influences PC through the gut-pancreas axis, with disruptions leading to inflammation and carcinogenesis. Exposure to toxic substances, including heavy metals and chemicals, is associated with increased PC risk. Glycome changes, such as abnormal glycosylation patterns, are significant in PDAC development and offer potential for early diagnosis. Interactions between environmental and genetic factors are crucial in PDAC susceptibility. Genome-wide association studies (GWAS) have identified several single nucleotide polymorphisms (SNPs) linked to PDAC, but gene-environment interactions remain largely unexplored. Future research should focus on polygenic risk scores (PRS) and large-scale studies to better understand these interactions and their impact on PDAC risk.

Direct Spectrophotometric Method for Determination of Cadmium (II) Ions Using Bis-Thiosemicarbazone

A novel and simple study outlines the advancement of a straightforward and precise spectrophotometric technique for the determination of Cd (II) ions. This method offers a notable benefit as it is a straightforward procedure that does not require additional purification or concentration of the solvent. The concentration of Cd (II) ions was determined in the presence of bis(indoline-2, 3-dione) thiosemicarbazone (L) at a pH of 12 using Briton-Robinson Buffer. The concentration range for Cd (II) ions in the method follows Beer's law and is between (1.8-17.8) × 10-5 mol L-1. The limit of detection is 0.245 μg mL-1(2.2 μmol L-1) and the limit of quantification is 0.817 μg mL-1 (7.3 μmol L-1). The molar ratio between L and Cd (II) ions was 1:2, ensuring the development of a metal complex. The applied method offers numerous benefits, including its simplicity, affordability, convenience of use, quick detection, minimal use of ligands, and high sensitivity. The sensitivity of the analytical approach was verified by carefully selecting appropriate experimental conditions. Additional insights into the composition and arrangement of the complex produced in a solution containing Cd (II) ions and the ligand (L) have been obtained by isolating and studying the solid complex L-Cd. The solid complex, L-Cd, was determined using analytical methods including elemental analysis, UV-Vis spectra, spectral mass, and thermal analysis.

Development of a novel low-cost adsorbent Chitosan@EDTA@Cellulose composite to effectively remove Methyl Orange dye from wastewater: Experimental and theoretical investigation

Methyl Orange, a toxic and persistent azo dye, poses significant environmental challenges in aquatic ecosystems. This study investigates the efficiency of a novel Chitosan@EDTA@Cellulose composite, synthesized by linking shrimp-derived chitosan and cactus-derived cellulose using EDTA as a linking agent. Comprehensive characterization techniques, including Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and Brunauer-Emmett-Teller surface area analysis, were employed. Under optimal conditions (pH 5, 50 mg/L dye concentration, 55 min, 0.1 g adsorbent), the composite achieved a maximum adsorption capacity of 55.87 mg/g, significantly outperforming chitosan (7.29 mg/g) and cellulose (5.69 mg/g). Adsorption followed the pseudo-second-order kinetic model and the Langmuir isotherm model, with thermodynamic analysis confirming a spontaneous and endothermic process. Competitive adsorption tests demonstrated >90 % removal efficiency despite the presence of interfering ions, attributed to the chelating properties of EDTA and the synergistic effect of the composite structure. Reusability tests showed a slight efficiency decline from 97.8 % to 81.86 % after four cycles. Box-Behnken Design optimization identified adsorbent mass, pH, and dye concentration as key factors in removal efficiency. Density Functional Theory analysis clarified the functional group interactions driving adsorption. These findings underscore the composite's potential as an effective and eco-friendly adsorbent for Methyl Orange removal.

Assessing heavy metal accumulation in the invasive blue crab (Callinectes sapidus): environmental and human health implications

Heavy metals are increasingly becoming a significant environmental concern, especially regarding food safety and security. This is especially concerning as the consumption of harvested marine species can pose potential health concerns. The arrival of the blue crab, Callinectes sapidus, to the Balearic Islands has led to the need to evaluate its environmental implications and potential as a food source as part of management efforts. In the present study, the concentrations of cadmium (Cd), lead (Pb), and mercury (Hg) in the muscle tissue of C. sapidus were evaluated at several locations in the Balearic Islands in the western Mediterranean Sea. A total of eighty-three blue crabs were examined (45 males and 38 females) and the concentrations of the heavy metals were evaluated. Regarding metal concentrations, overall, Hg was the most present followed by Cd and then Pb. Concentrations were also site dependent, with Es Grau having the highest Hg concentrations while in s'Albufereta the highest Cd concentrations were observed. Moreover, differences in metal accumulation were also observed between sexes, with juveniles and females exhibiting higher Cd concentrations than males. Furthermore, regarding potential human health concerns for consumption, the margin of exposure (MOE) for Pb were all above 1 and the estimated weekly ingestion (EWI) for Cd and Hg, were all below the established guidelines for food safety. These results highlight that the consumption of C. sapidus from the Balearic Islands does not currently pose a health risk the recreational fisheries sector. Considering these findings, the muscle tissue of C. sapidus is a valuable bioindicator for monitoring heavy metal levels, and continued site-specific monitoring is recommended for the coastal ecosystems of the Balearic Islands.

A SiC DSRD-based pulse generator with sub-nanosecond, high frequency and high-voltage for desulfovibrio sulfate-reducing bacteria ablation

Sulfate-reducing bacteria (SRB) are ubiquitous in industrial wastewater. As a type of slime bacteria, they tend to combine with suspended solids to form slime, interfering the normal operation of purification equipment. As heterotrophic bacteria, they produce harmful gases such as hydrogen sulfide and methane under anaerobic conditions, which not only accelerate equipment corrosion but also further deteriorate water quality. However, current treatment methods for these bacteria are not yet adequate, and traditional methods are often costly and may cause secondary pollution to the water body. In recent years, the scientific community has been actively exploring novel sterilization technologies to effectively address the challenges posed by sulfate-reducing bacteria. Among them, Pulsed Electric Field (PEF) technology stands out due to its unique advantages. By applying high-intensity electric field pulses, PEF technology can cause fatal damage to microbial cells within an extremely short period, manifested as membrane perforation and disruption of cellular structures, ultimately leading to cell death. PEF technology not only exhibits high sterilization efficiency but also ensures the environmental friendliness of the treatment process. Despite the tremendous potential of PEF technology in theory, its practical application research in the field of bacterial purification is still relatively limited. In particular, the effectiveness of high-frequency, narrow-pulse-width PEF on slime heterotrophic bacteria (such as sulfate-reducing bacteria) requires further investigation and experimental validation. To fill this research gap, our team utilized a newly developed pulsed power supply device based on SiC-DSRD to investigate the effects of bio-electromagnetic effects on desulfovibrio sulfate-reducing bacteria (DSRB). This device features an adjustable voltage range (from 5 kV to 1 kV), a pulse width of less than 10 ns, and a maximum frequency of 100 kHz. Experimental results indicate that after treating the sulfate-reducing bacteria solution with this device, the growth rate of the bacteria was less than 9 % after 24 h, whereas the growth rate of bacteria in the same batch and concentration without treatment exceeded 300 %. This study provides strong experimental support for the application of PEF technology in industrial wastewater treatment and expands the methods for bacterial treatment in industrial wastewater.

The impact of salinity on heavy metal accumulation in seaweed

Aquatic heavy metal pollution, driven by industrialization and climate change, threatens marine ecosystems through bioaccumulation. Climate-induced salinity fluctuations influence metal speciation and bioavailability in coastal environments. Seaweeds, crucial for nutrient cycling and economic use, exhibit species-specific metal uptake under varying salinity conditions. This study employs bibliometric analysis to examine research trends from 1995 to 2024 on the impact of salinity on metal accumulation in seaweeds. A search conducted on 8 October 2024 resulted in 242 articles, which were then filtered to 28 relevant studies for analysis. Using the Web of Science Core Collection, these articles were analyzed with VOSviewer and Bibliometrix to identify key contributors, collaborations, and research themes. Results reveal a growing academic interest since 2006, with increasing citation counts reflecting global concern over salinity and heavy metal pollution. Significant contributions from Brazil and Portugal, alongside strong European collaborations, highlight regional strengths. Five key themes emerge, encompassing seaweed physiology, biomonitoring, and phytoremediation. Findings indicate that salinity fluctuations significantly affect metal bioavailability and uptake in seaweeds, influenced by species-specific factors, temperature, and pH. This study highlights the need for targeted, site-specific research on diverse seaweed species to effectively manage heavy metal pollution in coastal ecosystems, particularly in light of climate change and industrial activities. Additionally, the research emphasizes the potential of seaweeds as bioindicators and bioremediators in environmental monitoring and pollution management.

Metal contaminant risk at active floating photovoltaic sites and future research roadmap

Floating photovoltaics (FPVs) are solar energy systems deployed in aquatic environments, sparing land for other uses. It has been nearly twenty years since photovoltaics were first deployed on water bodies as FPVs. However, the potential for FPVs to contaminate host basins with metals due to some FPV components containing metals is understudied. We conducted a pilot study investigating cadmium (Cd), chromium (Cr), iron (Fe), manganese (Mn), lead (Pb), and tin (Sn) concentrations and their variability at FPV sites in two states in the United States. Next, we contextualized these results using the heavy metal evaluation index (HEI) to understand risks to human health. We found that the predominant metals at the FPV sites were Fe and Mn, and Cd was the least occurring metal. The greatest and least variable metals were Fe and Cd for the study sites. The total mean concentration of metals from the "FPV" and "Open" nodes at the FPV site for SITE 1 (59.92 ppb) was lower than the reference "Control" (76.43 ppb), the latter driven predominantly by the presence of Fe and Mn. The HEI revealed that water at the FPV-host basins have metal concentrations two orders of magnitude below the threshold for low metal pollution (<10), interpreted as safe for drinking. We leveraged these results and those from previous studies to develop an experimental framework and conceptual roadmap to guide future experimental research toward establishing high confidence in metal source attribution at FPV sites.

Marketing of Freshwater and Marine Fish Species in Alexandria City, Egypt: Human Health Risk of Specific Metals

Fish intake may constitute a significant route by which humans are exposed to metals, especially people who depend on fish as a source of protein as Alexandrians. Therefore, this study aimed to investigate the metal contents in muscles in eight commonly consumed freshwater (Tilapia, Catfish, and Common Carp) and marine fish species (Emperors, Groupers, Mackerels, Silver Pomfret, and Roving Groupers) collected from the local markets located in Alexandria City for a 1-year calendar year, 2022. Seasonal variations in the levels of the tested metals in the fish species, with significant differences between the species, were recorded. Also, the levels of Cu, Zn, Fe, Co, and Cd in all the tested fish species collected during the experiment did not exceed the guideline limits, while Ni, Cr, and Pb in fish collected during October-May, June-September, and February-May 2022, respectively, exceeded the permissible limits settled by FAO and WHO. Additionally, Mackerels and Roving Groupers had high-level contents of Mn that exceeded the permissible limits settled by European Commission. The accumulation of these metals in muscles of different fish species had relative variation in the accumulation, and Cu was the most predominant element in Tilapia, Zn in Catfish, Roving Groupers, and Mackerels, Fe in Common Carp, Groupers, Emperors, and Silver Pomfret, and Co in Tilapia. Consumption of fish with a high Metal Pollution Index (MPI) value may pose a potential public health risk. On the meantime, the calculated values of estimated daily intakes (EDI), hazard index (HI), and target health quotient (THQ) indicated no potential health risk for Alexandrians via the consumption of these fish species because they did not exceed the World Health Organization's acceptable daily intake.

Thalassophryne maculosa (Batrachoididae: Thalassophryninae) as a Bioindicator of Mercury-Induced Genotoxicity

Environmental monitoring requires reliable bioindicators to assess the genotoxic effects of pollutants in aquatic ecosystems. In this study, the marine fish Thalassophryne maculosa was evaluated as a bioindicator of genotoxicity through the application of the micronucleus test. Fish were exposed to varying concentrations of mercuric chloride (HgCl2) (0.1, 0.25, and 0.5 µg HgCl2/g body weight) over different time intervals (24, 48, 72, and 96 h). A dose- and time-dependent increase in nuclear abnormalities, including micronuclei, was observed, with significant chromosomal damage detected at 0.25 and 0.5 µg HgCl2/g body weight. These results demonstrate the sensitivity of T. maculosa to mercury exposure, even at concentrations below regulatory safety thresholds, emphasizing its suitability as a bioindicator for detecting genotoxic contamination in coastal ecosystems. This study provides critical insights into the ecological risks posed by mercury and highlights the potential of T. maculosa to enhance environmental monitoring programs, particularly in regions vulnerable to heavy metal pollution.

The Neurobehavioral Impact of Zinc Chloride Exposure in Zebrafish: Evaluating Cognitive Deficits and Probiotic Modulation

Zinc contamination in aquatic environments has become a growing concern due to its potential to bioaccumulate and induce neurotoxic effects in aquatic organisms. As an essential trace element, zinc plays a crucial role in various physiological processes, but excessive exposure can disrupt the gut-brain axis, leading to cognitive and behavioral impairments. Recent studies have suggested that probiotics may offer protective effects against environmental neurotoxins by modulating the gut microbiota and associated neurological functions. The zebrafish (Danio rerio) has emerged as a valuable model organism for studying the biological mechanisms underlying neurotoxicity and potential therapeutic interventions. This study aimed to assess the effects of probiotics on cognitive impairments induced by zinc chloride (ZnCl2) exposure in zebrafish. Specifically, zebrafish were exposed to ZnCl2 at concentrations of 0.5 mg/L and 1.0 mg/L for 96 h, followed by a 7-day post-exposure period to probiotics (Bifidobacterium longum, Bifidobacterium animalis lactis, Lactobacillus rhamnosus). ZnCl2 exposure at these concentrations is already known to induce behavioral and neuromotor deficits resembling Alzheimer's disease-like symptoms in zebrafish models, making it a suitable model for evaluating the neuroprotective potential of probiotics. Behavioral assessments including sociability tests along with short- and long-term memory evaluations were conducted using EthoVision XT 16 software. Memory tests demonstrated that ZnCl2 exposure impaired cognitive functions, while probiotic treatment did not significantly ameliorate these deficits. In the social behavior test, ZnCl2 at 0.5 mg/L resulted in a marked decrease in sociability, whereas exposure to 1.0 mg/L did not induce significant changes. However, post-exposure probiotic administration following ZnCl2 intoxication at 1.0 mg/L exhibited an anxiolytic effect on zebrafish. These findings suggest that probiotics may exhibit partial neurobehavioral benefits following zinc chloride-induced toxicity, particularly in mitigating anxiety-like behaviors rather than cognitive deficits. Further investigations are needed to elucidate the precise mechanisms by which probiotics interact with the gut-brain axis in the context of heavy metal neurotoxicity.

Evaluation of heavy metal pollution and ecological risk of surface sediments in a tropical mountainous River-Estuary-Shelf Continuum system: A case study of the Selangor River, Malaysia

As human activities continue to increase, the global production of pollutants has increased significantly, with the majority of pollutants being transported to the ocean via rivers, resulting in intensified pollution in estuaries and coastal areas. To maintain a healthy marine ecological environment, it is necessary to consider rivers, estuaries, and coastal seas as integrated systems and implement pollution management based on the concept of land-ocean integration. In this study, heavy metal elements in the surface sediments of Selangor River-Estuary-Coastal Shelf Continuum were collected and analysed to assess their pollution levels and potential ecological risks. The results show that the heavy metal content is high in the downstream and estuarine regions, with a general decreasing trend observed from nearshore to offshore in the coastal shelf area. The heavy metal pollution assessment indicates that the surface sediments of the Selangor River-Estuary-Coastal Shelf continuum were contaminated, with the most severe pollution occurring downstream and within the estuary. The pollution levels gradually decrease after exiting the estuary. The ecological risk associated with heavy metal pollution in rivers, estuaries, and southeastern coastal areas was classified as moderate to serious, whereas other areas exhibited only slight ecological risks. Specifically, As causes serious pollution in the river and estuary, with moderate-to-serious pollution in the coastal shelf area and moderate-to-serious ecological risks, mainly originating from mining within the river basin. Pb causes moderate pollution in the river, estuary, and coastal areas, with slight ecological risks due to mining within the river basin and inputs from nearby rivers, ports, and industrial activities. Other heavy metals cause minor pollution and pose minimal ecological risks.

The adsorption behavior and mechanism of Cu(Ⅱ), Fe(Ⅱ) and Co(Ⅱ) on straw biochar and their Fenton-like performance for ciprofloxacin decontamination

In this study, the adsorption of aqueous Cu(Ⅱ), Fe(Ⅱ), and Co(Ⅱ) on biochars at diverse synthesized temperatures was evaluated. The optimal sample BC-800 achieved superior adsorption performance of Cu(Ⅱ), Fe(Ⅱ), and Co(Ⅱ) at 10-50 mg L-1 initial concentration. Due to the larger surface area (349.6 m2/g), total pore volume (0.24 cm3/g), average pore diameter (6.4 nm), higher degree of graphitization (IG/ID = 1.00) and stable aromatic carbon structure, BC-800 achieved excellent adsorption of Cu(Ⅱ), Fe(Ⅱ), and Co(Ⅱ) through multilayer chemical adsorption, corresponding to the pseudo-2nd-order and Freundlich model (Qm Cu(Ⅱ) = 433.4 mg g-1, Qm Fe(Ⅱ) = 472.0 mg g-1 and Qm Co(Ⅱ) = 301.0 mg g-1). After then, the adsorbed biochars with Cu(Ⅱ), Fe(Ⅱ), and Co(Ⅱ) were directly used as heterogeneous catalysts in Fenton-like reaction for ciprofloxacin (CIP) degradation. Compared with Co-BC-800/peroxymonosulfate (PMS) system, Co-BC-800/H2O2 system exhibited the 56.6% decontamination of CIP with lower ions leaching (0.53 mg/L) within 70 min. The 97.9% of CIP was finally removed by Co-BC-800/H2O2 under optimized conditions: initial pH = 6.94, catalyst dosage = 1.0 g L-1, H2O2 concentration = 0.44 g L-1. Furthermore, Co-BC-800 exhibited superior acid-base adaptability (2.94-10.94) and anti-anion interference ability. The removal of CIP was achieved by the synergistic effect of adsorption and oxidative degradation. This study proposes some insights into the behavior and mechanism of metal ions adsorption on biochar and hazardous waste treatment.

Can Aluminum Affect Social Behavior and Cortisol Plasma Profile in the Neotropical Freshwater Teleost Astyanax lacustris (Teleostei: Characidae)?

Aluminum (Al) can cause endocrine disruption in aquatic animals, but assessments of animal social behavior in neotropical teleost fish species with importance for Brazilian aquaculture have still not been addressed so far, which can further complete this ecotoxicological knowledge. In order to evaluate the social behavior and plasma cortisol concentration of fish exposed to Al, we performed a 1 h acute exposure with Astyanax lacustris couples in three different experimental groups: control in neutral pH (CTL/n group), acid pH (pH/ac group), and aluminum in acid pH (Al/ac group; 2.0 mg L-1). An ethogram of social interactions between males and females and swimming activities were performed. Furthermore, the cortisol plasma concentration was measured by enzyme-linked immunosorbent, and the gonadal maturation stage of the animals was evaluated by histology. Adult and mature females in the CTL/n and pH/ac groups were more aggressive and active than mature males, including several attacks on the male. Moreover, males did not present attack behavior in these groups at any time, but did show submission behavior and constant avoidance of female attacks. In the Al/ac, females did not attack males, couple decreased swimming activity, a repetitive movement toward the aquarium surface, and high mucus production were observed, making the water cloudy. Regarding cortisol plasma concentration, males had higher cortisol plasma concentrations than females in the CTL/n and pH/ac groups, which was not observed in the Al/ac group. Therefore, Al in addition to being described in the literature as an endocrine disruptor, it can be considered as behavioral disrupter in A. lacustris in this important freshwater species cultivated in South America.

Mycoremediation of heavy metals by Curvularia lunata from Buckingham Canal, Neelankarai, Chennai

The spread and mobilization of toxic heavy metals in the environment have increased to a harmful level in recent years as a result of the fast industrialization occurring all over the world to meet the demands of a rising population. This research aims to analyze and evaluate the mycoremediation abilities of fungal strains that exhibit tolerance to heavy metals, gathered from water samples at Buckingham Canal, Neelankarai, Chennai. Water samples were examined for heavy metal analysis, and the highest toxic heavy metals, Zn, Pb, Mn, Cu, and Cr, were recorded. Three fungal strains were isolated and named EBPL1000, EBPL1001, and EBPL1002 were selected by primary screening (100 ppm) for further studies. Out of three fungal isolates, EBPL1000 grew in all five heavy metal concentrations and showed 2100 ppm as the highest Maximum Tolerance Concentration toward Lead, 2000 ppm tolerance in Zinc and Manganese, 1700 ppm in Chromium, and 1500 ppm in copper, respectively. The fungal isolate EBPL1000 was identified as Curvularia lunata with 100% percentage identity and query coverage. The Biosorption result reveals that lead is the highest biosorbed heavy metal with 79.99% at 100 ppm concentration while copper is the lowest biosorbed with 24.11% heavy metal at 500 ppm concentration. The uptake of Manganese by Curvularia lunata biomass was the highest (5.64 mg/g) of all heavy metal's uptake at 100 ppm concentration. The lowest uptake of heavy metals was copper (0.43 mg/g) at 500 ppm concentration, and the growth profile study under heavy metals stress conditions shows the order of Pb > Mn > Zn > Cr > Cu at 60 h of time intervals at 100 ppm concentration. In addition to the research, FTIR analysis and Molecular Docking studies provide credence to the idea that Curvularia lunata has high biosorption potential and uptake or removal of toxic heavy metals at low cost and in an eco-friendly way from the contaminated environment.

Nano-Fe3O4/FeCO3 modified red soil-based biofilter for simultaneous removal of nitrate, phosphate and heavy metals: Optimization, microbial community and possible mechanism

The pollution of nitrogen, phosphorus and heavy metals in surface water is becoming more and more serious, affecting the safety of water quality. In this study, three biofilters were constructed using iron-modified red soil-based filler carriers (RSC, nano-Fe3O4@RSC, and FeCO3@RSC) combined with strain Zoogloea sp. ZP7 to simultaneously remove nitrate (NO3--N), phosphate (PO43--P), copper (Cu2+), and zinc (Zn2+). The long-term operation results showed that the three groups of biofilters could remove 85.0 %, 90.0 %, and 89.8 % of NO3--N, respectively. Furthermore, the addition of iron compounds enhanced the removal of PO43--P and the resistance to the stress of Cu2+ and Zn2+ in the biofilter. The analysis illustrated that iron modification improved the redox activity and zeta potential of RSC surface. The secondary structure analysis of the protein showed that the microbial secreted proteins were more compact on the surface of the iron-modified RSC, which facilitated the formation of biofilm on the carrier surface. In addition, the iron-modified RSC-based biofilter also showed excellent NO3--N and PO43--P removal efficiency in the treatment of actual surface water. The microbial community analysis results showed that Zoogloea became the dominant species in the biofilter. On the other hand, the presence of iron-reducing bacteria and the expression iron cycle-related genes may contribute to denitrification under low nutrient conditions.

Effects of mercury and magnetic fields on the activity of proteinases and glycosidases in the intestine of common carp Cyprinus carpio

Aquatic ecosystems are increasingly affected by anthropogenic pollution, including heavy metals like mercury, which accumulate in organisms and cause harmful effects. At the same time, human activities such as industrial operations and the use of electric power lines also alter the magnetic background in natural water bodies. However, the interaction between mercury exposure and magnetic fields remains poorly understood. This study aimed to investigate the combined effects of mercury and magnetic fields on the digestive enzyme activity of common carp (Cyprinus carpio), focusing on the relevance of magnetic fields due to their increasing presence in industrialized environments. Two groups of fish were fed diets with low (0.02 mg/kg) or high (0.27 mg/kg) mercury content for 6 months and exposed to extremely low-frequency magnetic fields or hypomagnetic conditions. Results showed significant differences in mercury accumulation between groups, with higher levels in carps fed with high-mercury content diets. These fish also exhibited increased body length and weight compared to those on a low-mercury diet. The amylolytic activity (total activity of enzymes hydrolyzing starch: α-amylase, glucoamylase, and maltase) and proteolytic activity (total activity of serine proteinases) in the fish intestine were assessed. Magnetic exposure had contrasting effects on enzyme activity, depending on mercury levels in the diet. Fish fed the low-mercury diet exhibited decreased amylolytic activity following magnetic field exposure, while fish on the high-mercury diet showed increased activity. Proteolytic activity followed a similar pattern, with opposite effects observed between the two dietary groups. These findings suggest that mercury accumulation alters the biological response to magnetic fields, possibly through compensatory biochemical mechanisms. Understanding the interactions between toxic substances and magnetic fields is critical for improving environmental risk assessments.