Aquatic Systems Research Articles

Impacts of Fire-fighting Chemicals on Native Fauna and Ecosystems in Australia: Identification of Key Knowledge Gaps and Research Priorities.

Increasing global wildfire frequency and intensity due to climate change has led to increasing use of fire-fighting chemicals (FFCs). While there is information relating to the environmental impacts of these FFCs in some regions, to date, there is little information on the impacts of FFCs on native fauna species and ecosystems in an extremely fire-prone country, Australia. We elicited input from a national-level interdisciplinary cohort of experts in fire research and management to identify fundamental gaps in knowledge and research priorities in the use and ecological impacts of FFCs in Australia. We used an anonymized online survey consisting of 21 close-ended, Likert-style and open-ended questions to collect expert opinion on the impacts and management of fire in Australia, focusing on the key knowledge gaps and research priorities relating to FFC use. Knowledge gaps and research priorities were identified in the areas of (1) the different types of FFCs recommended for use in Australia, (2) short and long-term effects of FFCs on fauna species and ecosystems, particularly in aquatic systems, and (3) interactions between FFCs and other environmental stressors. Addressing these knowledge gaps and research priorities will provide scientific-based evidence and recommendations for FFC use to inform future fire management practice and policy in Australia and can guide similar approaches in other countries requiring extensive FFC use for wildfire management.

Facile Synthesis and Characterization of Novel CoFe2O4@MgO@(Mg0.23Co0.77)(Mg0.35Co1.65)O4@C and CoFe2O4@MgO@C Nanocomposites for Efficient Removal of Zn(II) Ions from Aqueous Media

Excessive levels of Zn(II) ions in aquatic environments pose significant risks to both ecosystems and human health. In aquatic systems, Zn(II) ions disrupt metabolic functions in organisms, leading to toxicity and bioaccumulation. For humans, prolonged exposure can result in gastrointestinal distress, immune system dysfunction, and neurological complications, necessitating effective removal strategies. This study reports the synthesis and characterization of CoFe-MgO-C-M600 (CoFe2O4@MgO@(Mg0.23Co0.77)(Mg0.35Co1.65)O4@C) and CoFe-MgO-C-M800 (CoFe2O4@MgO@C) nanocomposites for the efficient removal of Zn(II) ions from aqueous media. The nanocomposites were synthesized using the Pechini sol-gel method and characterized through X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM). XRD analysis confirmed the crystalline structure of both nanocomposites, with CoFe-MgO-C-M600 exhibiting a smaller average crystallite size (38.67 nm) than CoFe-MgO-C-M800 (75.48 nm). EDX results verified the elemental composition of the nanocomposites, ensuring the successful incorporation of key elements. FE-SEM analysis revealed significant morphological differences, with CoFe-MgO-C-M600 displaying smaller and more uniform grains compared to CoFe-MgO-C-M800. The results show that CoFe-MgO-C-M600 possesses a highly porous and interconnected structure, enhancing its surface area and adsorption potential. In contrast, CoFe-MgO-C-M800 demonstrates larger and more compact grains, which may affect its adsorption performance. HR-TEM further confirmed these findings, demonstrating that CoFe-MgO-C-M600 had a smaller average particle diameter (35.45 nm) than CoFe-MgO-C-M800 (321.14 nm). Adsorption studies indicated that CoFe-MgO-C-M600 and CoFe-MgO-C-M800 achieved maximum adsorption capacities of 276.24 and 200.00 mg/g, respectively. The adsorption process was determined to be exothermic, spontaneous, and physical in nature, following the pseudo-second-order kinetic model and the Langmuir isotherm.

Microplastic pollution of thermal waters in Kütahya, Turkey.

Microplastics (MPs) are emerging pollutants in aquatic systems, but their presence in groundwater, particularly thermal waters, is understudied. This study investigates the prevalence and characteristics of MPs in the thermal waters of Kütahya, Turkey, marking the first such exploration in the country and globally in thermal groundwater systems. Twenty-one samples (3 L each) were collected across nine regions and filtered using GF/C filters (0.45-µm pore size). Microscopic examination and μ-Raman spectroscopy revealed an average MP concentration of 0.85±0.71 MPs/L (850 MPs/m3), with the highest at ST-8 (4.88±2.98 MPs/L). Fibers (50%), fragments (39.8%), and films (10.2%) were identified, with polyethylene (22.2%) being the most common polymer type. Variability in MP abundance across stations suggests multiple contamination sources, including agricultural runoff, anthropogenic activities, and material used in water transport infrastructure. The findings indicate low-level MP contamination in thermal groundwater systems, which could influence both ecological health and human activities relying on these waters, such as thermal tourism and greenhouse irrigation. This pioneering study highlights the necessity for integrated waste management policies to mitigate MP pollution and underscores the role of thermal waters in understanding the transport dynamics of MPs in groundwater systems.

A first- time study of cyclic volatile methylsiloxanes in wastewater, sludge, lagoon water, sediments and fishes from Africa.

Cosmetic and personal care products are used throughout the world in large quantities. Siloxanes are commonly used in the formulation of these products. The use of these products releases siloxane into the environment. This study quantifies for the first time in Africa specifically in Lagos Nigeria, the amount of two cyclicvolatile methylated siloxane (cVMS) compounds namely octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) in wastewater and sludge from industries, water, sediments and fishes from the Lagoon. The samples obtained were extracted and analyses were performed using gas chromatography-mass spectrometry (GC-MS). Results showed higher concentrations of D5 compared with D4 across all sample types. Using the estimated daily intake (EDI) and hazard quotient (HQ) to assess the health risks showed minimal risk to adults and children consuming fish from the lagoon. However, biota-sediment accumulation factor (BSAF) and bioaccumulation factor (BAF) exceeded their benchmark values of 1.7 and 5000 respectively for most of the fishes at all the sites showing bioaccumulation potential at these sites for D4 and D5. This study underscores the need for sustainable practices to mitigate cVMS contamination in Nigeria's aquatic systems.

Settling velocities of microplastics with different shapes in sediment-water mixtures.

Settling velocities of microplastics with different shapes in sediment-water mixtures.

Simulated sunlight-enhanced peroxymonosulfate activation via S-scheme BiOBr/g-C3N4 aerogel heterojunction for multi-pollutant remediation: Band structure and interface engineering.

Simulated sunlight-enhanced peroxymonosulfate activation via S-scheme BiOBr/g-C3N4 aerogel heterojunction for multi-pollutant remediation: Band structure and interface engineering.

Tire-based microplastics: Composition, detection, and impacts of advanced oxidation processes in drinking water treatment.

Tire-based microplastics: Composition, detection, and impacts of advanced oxidation processes in drinking water treatment.

The Occurrence of Micropollutants in the Aquatic Environment and Technologies for Their Removal

The presence of micropollutants in aquatic environments is an increasing global concern due to their persistence and potential harmful effects on aquatic organisms. Among the most concerning of these micropollutants are microplastics, pharmaceutical compounds, personal care products, and industrial chemicals, posing a significant threat to human health and aquatic ecosystems. This issue is further exacerbated by the diverse sources and complex physicochemical properties of micropollutants, as well as the inability of conventional water and wastewater treatment systems to effectively remove these contaminants. The removal of micropollutants is therefore becoming increasingly important, leading to extensive research into various physicochemical, biological, and hybrid treatment methods aimed at minimizing their environmental impact. This review examines the classification, occurrence, and associated environmental and health risks of commonly detected micropollutants in aquatic systems. Additionally, it provides an overview of advanced treatment methods being developed to implement a fourth purification stage in wastewater treatment plants. Biological, chemical, physical, and hybrid purification technologies are critically reviewed, with a focus on their performance characteristics and potential applications.

Water quality and diarrhoeagenic Escherichia coli detection in surface Pampean aquatic systems.

Many surface water systems are impacted by point source pollution from sewage discharges and industrial wastes, as well as diffuse pollution from agriculture and livestock farming, inducing a potential biohazard to human, animal, and environmental health. This study aimed to determine the presence of diarrhoeagenic Escherichia coli (DEC) pathotypes and their antibiotic resistance, as well as the bacteriological, physical, and chemical water quality conditions in two Pampean peri-urban rivers (Rojas and Salado rivers, Buenos Aires, Argentina) used for recreation. Additionally, we explored the impact of the surrounding land use on the water quality. In the Rojas (R) and Salado (S) rivers, wastewater discharges from treatment plants increased nutrient content and coliform abundances at specific sampling sites (R2 and S3) and downstream (R3 and S4, respectively). Coliform abundances correlated with ammoniacal nitrogen concentrations, both exceeding recreational use guidelines. Out of 36 samples positive for DEC virulence factors, 11 DEC strains were isolated (5 enteroaggregative, 3 enteropathogenic, 1 shigatoxigenic-stx1/stx2, 1 shigatoxigenic-stx2, 1 hybrid enteroaggregative-enterotoxigenic). Six strains were resistant to one or more antibiotics. Our results suggest that differences in E. coli pathotypes between the two rivers and the water quality of each sampling site are linked to the surrounding land use, evidencing both diffuse and point source pollution.

Occurrence of pharmaceuticals in muscle tissue of red drum (Sciaenops ocellatus) across subtropical estuaries: Comparison to blood plasma and implications for human exposure.

Occurrence of pharmaceuticals in muscle tissue of red drum (Sciaenops ocellatus) across subtropical estuaries: Comparison to blood plasma and implications for human exposure.

Influence of spatio-temporal variations in precipitation and temperature on the productivity of Eastern Lake Kyoga, Uganda

Spatio-temporal variations in precipitation and temperature affect productivity in aquatic systems, mainly through nutrient dynamics. Shallow lakes are more vulnerable to spatio-temporal variations, yet they are an important resource for biodiversity conservation, water supply and fisheries. The eastern arm of Lake Kyoga experiences two dry and two wet seasons annually, yet there is no information on how they affect its productivity. This study, therefore, focused on determining how spatio-temporal variations in temperature and precipitation influence production using chlorophyll-a (Chl-a) as a proxy indicator parameter. Seventeen sampling sites were established for data collection during both dry and wet seasons. Fifteen physico-chemical and biological parameters like total suspended solids (TSS), total phosphorus (TP), and chlorophyll-a were used for assessment. Thirteen of the 15 parameters had increased concentrations during the dry season, with only TSS and water temperature increasing during the wet season. Chlorophyll-a showed significant (p = 0.007) spatio-temporal variations between seasons. It significantly correlated with nitrate (r = 0.964), SRSi (r = 0.901), conductivity (r = 0.970) and pH (r = 0.936) during the dry season. Spatio-temporal variations influence nutrient dynamics, and therefore productivity in Lake Kyoga. These results are critical and should guide the water managers, decision, and policy-makers to develop appropriate mitigation approaches against impacts of spartio-temporal variations on the productivity of Lake Kyoga and its ecosystem.

Glyphosate is a transformation product of a widely used aminopolyphosphonate complexing agent

Diethylenetriamine penta(methylenephosphonate) (DTPMP) and related aminopolyphosphonates (APPs) are widely used as chelating agents in household and industrial applications. Recent studies have linked APP emissions to elevated levels of the herbicide glyphosate in European surface waters. However, the transformation processes and products of APPs in the environment are largely unknown. We show that glyphosate is formed from DTPMP by reaction with manganese at near neutral pH in pure water and in wastewater. Dissolved Mn2+ and O2 or suspended MnO2 lead to the formation of glyphosate, which remains stable after complete DTPMP conversion. Glyphosate yields vary with the reaction conditions and reach up to 0.42 mol%. The ubiquitous presence of manganese in natural waters and wastewater systems underscores the potential importance of Mn-driven DTPMP transformation as a previously overlooked source of glyphosate in aquatic systems. These findings challenge the current paradigm of herbicide application as the sole source of glyphosate contamination and necessitate a reevaluation of water resource protection strategies.

Intermittent swimmers optimize energy expenditure with flick-to-flick motor control

Abstract Intermittent swimming behaviour is commonly observed in larval zebrafish, often attributed to energy-saving mechanisms. In this study, we utilize a hybrid approach combining deep reinforcement learning and the immersed boundary–lattice Boltzmann method to train a larval zebrafish-like swimmer to reach a target with minimized energy expenditure. We find that when the tail-beat period is fixed, continuous swimming emerges as the optimal strategy. However, when the tail-beat period is allowed to vary, intermittent swimming proves superior in energy performance, achieved through reductions in tail-beat amplitude and frequency. Our detailed analysis reveals that intermittent swimmers employ rapid backward tail flicks to attain high speeds, coupled with slower forward tail flicks and coasting phases to conserve energy. Furthermore, we derive scaling laws governing the swimming performance of trained fish. These results offer valuable insights into the intermittent swimming patterns of fish, with implications for understanding bio-inspired locomotion and informing the design of energy-efficient aquatic systems.

Bioavailability of Al, Fe, Mn and Zn in a Decommissioned Mining Area Evaluated by Biomonitoring and Passive Samplers: Robustness, Efficiency and Relationships Between Biotic and Abiotic Monitoring Approaches.

In situ assessment of metal bioavailability is crucial for evaluating the degree of contamination in aquatic systems. This study evaluated the bioavailability of Al, Fe, Mn and Zn in water from three sites in a decommissioned mining area near the city of Poços de Caldas (State of Minas Gerais, Brazil). A multi-tool approach was used, combining DGT, transplanted fish (Oreochromis niloticus) and water samples (total and dissolved metal concentration analyses). Samples were taken at 14, 28 and 42-day intervals. Livers, gills and muscles of transplanted fish were analyzed after acid digestion in microwaves and determined by ICP-OES. Significant increases in transplanted fish for Mn and Zn concentrations were observed in the gills. Total and dissolved concentrations showed large fluctuations, possibly influenced by factors such as the rainy season, pH changes, and varying effluent discharges at each sampling point. The concentration of the element measured by DGT devices, proved to be an effective indicator of temporal and spatial variations in the bioavailable levels of Al, Fe, Mn and Zn across all sites analyzed. However, the weak correlations between the different monitoring methods highlight their complementary nature, as each approach captures distinct aspects of metal bioavailability. This underscores the importance of integrating multiple methodologies to provide a more comprehensive understanding of metal dynamics in complex environmental scenarios.

Accumulation and Clearance of Polystyrene Microplastics in Brine Shrimp and the Responses of Microbiome and Metabolism

To investigate the accumulation kinetics of microplastics （MPs） with different characteristics in zooplankton and the related biological effects, the accumulation and clearance of polystyrene microplastics （PS-MPs） with different concentrations and particle sizes in brine shrimp （Artemiasaline） were analyzed under different nutritional conditions. The responses of microbial communities and metabolic functions in brine shrimp were revealed using the combination methods of microbiome and metabolome. The results showed that the accumulation and clearance rate of PS-MPs in brine shrimp increased with the increase in exposure concentrations, showing a concentration-dependent manner. On the contrary, the accumulation and clearance of PS-MPs in brine shrimp were negatively correlated with their particle sizes. The nutritional condition did not alter the accumulation kinetics of PS-MPs in brine shrimp, indicating that short-term feeding may have had no effect on the uptake and clearance of PS-MPs in brine shrimp. Compared to that in the control, exposure to PS-MPs significantly enhanced the diversity of the microbial community in brine shrimp. The proportions of Proteobacteria and Acinetobacter were increased by 0.4 folds and 12.3 folds, respectively, whereas the proportions of Firmicutes and Bacillus were decreased by 43% and 86%, respectively. This finding indicates that PS-MPs may have caused an imbalance of the bacterial community in brine shrimp by inhibiting the beneficial bacteria and stimulating the harmful bacteria, thus disrupting the metabolic function in brine shrimp. In addition, exposure to PS-MPs resulted in a production of 2 311 different metabolites in brine shrimp and mainly disrupted the pyrimidine metabolism and the biosynthesis of dermal sulfate/chondroitin sulfate in brine shrimp, leading to toxicity in the shrimp. The accumulation and biological effects of MPs with different characteristics in zooplankton may further affect the stability of aquatic systems, leading to unpredictable ecological risks.

Enhanced nitrate removal in aquatic systems using biochar immobilized with algicidal Bacillus sp. AK3 and denitrifying Alcaligenes sp. M3: A synergistic approach.

This study investigates the effectiveness of biochar immobilized with algicidal Bacillus sp. AK3 and denitrifying Alcaligenes sp. M3 in mitigating harmful algal blooms (HABs) and reducing nitrate pollution in aquatic environments. Over a six-day period, we analyzed changes in algal bloom-forming Microcystis density, chlorophyll-a levels (indicative of algal biomass), nitrate concentration, and microbial community composition in water treated with biochar and Bacillus sp. AK3 and Alcaligenes sp. M3-immobilized biochar. In water treatment using the AK3 and M3-immobilized biochar, Microcystis density decreased from 600,000 cells/mL to 80,000 cells/mL, and chlorophyll-a concentrations also substantially reduced, from 85.7 µg/L initially to 42.8 µg/L. Nitrate concentrations in the AK3 and M3-immobilized biochar treatment significantly decreased from approximately 23 mg/L to around 14 mg/L by Day 6, demonstrating the enhanced denitrification capabilities of the immobilized Alcaligenes sp. M3 and associated bacterial communities. The results also showed significant shifts in bacterial communities, with a decrease in Microcystis, highlighting the specific algicidal activity of Bacillus sp. AK3. The study underscores the potential of biochar-based treatments as a sustainable and effective approach for improving water quality and mitigating the environmental impacts of nutrient pollution and HABs.

Analytical approaches for quantifying and characterizing microplastics: Environmental impacts and bioaccumulation in aquatic Systems

Analytical approaches for quantifying and characterizing microplastics: Environmental impacts and bioaccumulation in aquatic Systems

Development of a new software for pore measurements in foraminifera and the constraints of pore proxy under high oxygen conditions

The rise in anthropogenic activities has significantly increased nutrient input into coastal habitats, such as lagoons and estuaries. This has led to increased eutrophication, which has considerably decreased the oxygen concentration in the aquatic systems. The pore patterns in benthic foraminifera have become a reliable proxy for accurately estimating the changes in these past oxygen conditions. However, there is currently no specific platform for a proxy study that can adequately quantify these pore structures and meet the requirements for pore image analysis in foraminifera. This study presents the new indigenously developed software MicroFoss42, specifically tailored for the pore morphometrics in foraminifera. It integrates computer vision and artificial intelligence to seamlessly extract the pore data from the images. Here, we demonstrate its use in measuring the pore count, diameter, area and circularity index of Ammonia parkinsoniana. Our results agree with the manual analysis, differing by less than 7.5%. This semi-automated software is designed to facilitate rapid analysis of the pore patterns in any foraminiferal species without the need for any prior datasets for training. Moreover, this study shows that the practical application of foraminiferal pore proxy in high oxygen conditions may be constrained.

Glacially-fed lakes of West Greenland have elevated metal and nutrient concentrations and serve as regional repositories of these materials.

Glacially-fed lakes of West Greenland have elevated metal and nutrient concentrations and serve as regional repositories of these materials.

Development and validation of a novel suspended particulate matter sampling device for analysis of particle-bound microbial communities.

Biotic and abiotic materials attachment to suspended particulate matter in aquatic systems can increase their toxicity and health impacts and has led to an increased need for consistent sampling across various compartments. Sedimentation traps and continuous flow centrifuges are the traditional tools for sampling suspended particulate matter, while manta trawls have been widely used for surface water sampling of suspended or floating microplastics. Limitations, however, exist in the cost of sampling and infrastructure needed to deploy such devices. Here we report on the construction and usage of a novel suspended particulate matter sampling device, the microParticle Obtaining Trap (mPOT). Quality control testing of the mPOT showed suspended particle recovery rates of >90% for particles 100 µm and larger, while field sampling of groundwater, lake and river water shows consistent, size-fractionated recovery of particulate matter. The mPOT is well suited to sample systems not easily accessible by boat or for particles not commonly recovered by common suspended particulate matter sampling and for collection of particles smaller than 300 µm in size.