Dissolved Oxygen Levels Research Articles

Spatial distribution and habitat suitability of seaweed on West Simeulue Island, Aceh Province, Indonesia

Seaweed is an important biological resource for human life, serving essential ecological functions, including providing shelter and feeding grounds for marine biota. Seaweed can be found in several Indonesian waters, growing naturally or through cultivation, including in the waters around Simeulue Island. This study aimed to assess the distribution of seaweed in relation to land suitability, using oceanographic parameters in Simeulue Island waters. The research was conducted at five stations within the West Teupah District, South Teupah District, and Alafan District. In situ measurements were taken to evaluate land suitability for seaweed growth based on oceanographic parameters such as current speed, depth, substrate type, salinity, temperature, pH, and dissolved oxygen. Results indicated that seaweed in Simeulue Island waters is distributed along the coastline and attached to coral reefs and rocks at depths of 2-5 meters. The total area of seaweed distribution is approximately 351.83 hectares along a coastline of 206.12 km. The measured parameters of seaweed habitats include a pH of 7.7 to 7.9, salinity of 31-35.3 ppt, temperature of 20-30 °C, dissolved oxygen levels of 3-4.8 mg/L, depth of 2-5 meters, current speed of 0.10 to 0.60 m/s, and a sandy coral substrate. Based on these water quality and substrate parameters, the seaweed habitats in Simeulue Island are classified as highly suitable, with suitability values ranging from 64 to 82. The recorded environmental conditions collectively support optimal seaweed growth.

Performances of full-scale biological nitrogen pre-treatment process for drinking water source: Seasonal variations and microbial community

This study investigated the performance of the full-scale unit over a two-year period to enhance nitrification efficiency and provide operational strategies. Results indicated that raw water quality from Donggan River was notably influenced by seasonal variations, particularly during dry and wet seasons, impacting the nitrification efficiency of the biological pretreatment process. Factors such as influent concentrations of ammonia and total Kjeldahl nitrogen were found to have significant effects on nitrification, with temperature and conductivity also showing correlations. The specific rate of ammonia removal was calculated to be approximately 0.1 kg-N/m3/d under the existing operational setup. Moreover, elevating dissolved oxygen levels above 4 mg/L was proposed to potentially boost ammonia oxidation based on findings from experiments conducted in lab-scale bioreactors. In times of increased influent ammonia levels, the elimination of about 1–3 mg-N/L of total nitrogen signified the activation of denitrification processes. This observation was corroborated by results from next-generation sequencing techniques, verifying the existence of denitrifying microorganisms. The real-time PCR analysis results indicated that the abundance of comammox amoA gene was comparable with the abundance of the AOB amoA gene, indicating the presence of comammox Nitrospira and their potential role on nitrification in the system.

A Variational Mode Decomposition–Grey Wolf Optimizer–Gated Recurrent Unit Model for Forecasting Water Quality Parameters

Water is a critical resource globally, covering approximately 71% of the Earth’s surface. Employing analytical models to forecast water quality parameters based on historical data is a key strategy in the field of water quality monitoring and treatment. By using a forecasting model, potential changes in water quality can be understood over time. In this study, the gated recurrent unit (GRU) neural network was utilized to forecast dissolved oxygen levels following variational mode decomposition (VMD). The GRU neural network’s parameters were optimized using the grey wolf optimizer (GWO), leading to the development of a VMD–GWO–GRU model for forecasting water quality parameters. The results indicate that this model outperforms both the standalone GRU model and the GWO–GRU model in capturing key information related to water quality parameters. Additionally, it shows improved accuracy in forecasting medium to long-term water quality changes, resulting in reduced root mean square error (RMSE) and mean absolute percentage error (MAPE). The model demonstrates a significant improvement in the lag of forecasting water quality parameters, ultimately boosting forecasting accuracy. This approach can be applied effectively in both monitoring and forecasting water quality parameters, serving as a solid foundation for future water quality treatment strategies.

Spatial heterogeneity, sediment-water exchange, and diffusion mechanisms of organophosphate esters from river to coastal aquatic system in a typical economic circle of northern China

Organophosphate esters (OPEs) have proven to be pervasive in aquatic environments globally. However, understanding their partitioning behavior and mechanisms at the sediment-water interface remains limited. This study elucidated the spatial heterogeneity, interfacial exchange, and diffusion mechanisms of 14 OPEs (∑14OPEs) from river to coastal aquatic system. The transport tendencies of OPEs at the sediment-water interface were quantitatively assessed using fugacity methods. The total ∑14OPEs concentrations in water and sediments ranged from 154 ng/L to 528 ng/L and 2.41 ng/g dry weight (dw) to 230 ng/g dw, respectively. This result indicated a descending spatial tendency with moderate variability. OPE distribution was primarily influenced by temperature, pH, and dissolved oxygen levels. As the carbon atom number increased, alkyl and chlorinated OPEs transitioned from diffusion towards the aqueous phase to equilibrium. In contrast, aryl OPEs and triphenylphosphine oxide, which had equivalent carbon atom counts, maintained equilibrium throughout. Diffusion trends of individual OPE congener at the sediment-water interface varied at the same total organic carbon contents (foc). As the foc increased, the fugacity fraction values for all OPE homologs showed a declining trend. The distinct molecular structure of each OPE monomer might lead to unique diffusive behaviors at the sediment-water interface. Higher soot carbon content had a more pronounced effect on the distribution patterns of OPEs. The sediment-water distribution of OPEs was primarily influenced by total organic carbon, sediment particle size, dry density, and moisture content. OPEs displayed the highest sensitivity to fluctuations in ammonium and dissolved organic carbon. This study holds significant scientific and theoretical implications for elucidating the interfacial transport and driving forces of OPEs and comprehending their fate and endogenous release in aquatic ecosystems.

Impact of Temperature on the Growth Performance, Survival Rate, Osmoregulation, Dissolved Oxygen and Physiological Changes of Freshwater Tilapia (Oreochromis mossambicus)

For many aquatic species, any changes in water temperature affect their survival. This study was performed to investigate the effect of rising temperature on the growth parameters, protein content, dissolved oxygen content, moisture content osmoregulation, and physiological activity of freshwater Tilapia (Oreochromis mossambicus). The experiments were set in plastic fish tanks, the experimental tank placed in direct sunlight and the control tank in shade, and measuring temperature and pH daily, with proper aeration and feed was provided. The study found that increasing water temperature led to higher mortality rates and low survivability percentages in fish, with a higher growth rate in the experimental group with a pH range of 5.7 to 8.2. High dissolved oxygen levels were recorded during the experimental period, with a mean difference of 26.56 compared to the control group, possibly causing restless movement in fish. The study revealed that the alkalinity of water decreases with increasing temperature. The study found that increased salinity led to a significant increase in growth performance, indicating an increase in metabolic rate, and a decrease in alkaline nature. The difference between the mean protein value in the experimental and control groups is 0.896mg/ml. Thermal limitations may negatively impact O. mossambicus physiological responses, impacting aquaculture production due to predicted global climate change-induced water temperature changes.

Pre-treatments to reduce metabolism in adult green-lipped mussel, Perna canaliculus, in preparation for live transportation

Improved sustainability of aquaculture can be achieved by reducing product wastage post-harvest. Aquaculture of the green-lipped mussel, Perna canaliculus, is an important industry for New Zealand, which increasingly exports to live markets. Live transport can keep mussels fresh, but mussels could also be susceptible to handling stresses. To remedy this, pre-treatments that make mussels metabolically depressed, and thus potentially less sensitive to external stressors, were explored. As indicators of depressed metabolism, heart rate (HR), inferred cardiac output (PCO), and relative gaping magnitude (RGM) were simultaneously monitored in mussels experiencing different temperatures, dissolved oxygen levels and anaesthetic (MgCl2) concentrations to compare their efficacy in inducing suppressed metabolism of adult P. canaliculus. We found complex interactions between HR, PCO, and RGM in response to these conditions; however, overall, these response variables were significantly correlated. Mussels showed depressed HR and PCO by up to 100% at 4 °C within 2 h, with correspondingly decreased RGM of up to 48%. Similarly, mussels immersed in 40 g L−1 MgCl2 suppressed HR by up to 97%, accompanied by up to 76% decrease in PCO, and a slight increase in RGM (11%) after 2 h. While responses were variable, low DO levels suppressed HR by up to 50%, yet PCO and RGM increased two- and threefold relative to control groups. The results of the present study indicated that 4 °C and 40 g MgCl2 L−1 were more effective conditions as pre-treatments than low dissolved oxygen lower the metabolism of P. canaliculus before live transport.

Polyculture of Genetically Improved Farmed Tilapia (GIF tilapia) and Penaeus vannamei Using Biofloc Technology – A Review

According to Food and Agriculture Organization of the United Nations (FAO), aquaculture has grown faster and its expansion aimed at meeting the increase of world fish demand, and preserving natural fish stocks. Currently, to produce fish in quantity and quality requires reduction of the environmental impact from aquaculture, through the improvement of culture systems. Disease is the major factor affecting the development and expansion in aquaculture. Losses due to disease in shrimp farming are high. Various approaches to minimize the impact of disease on production are possible. Another approach to keep the pathogen pressure low is polyculture of shrimp and finfish. This practice makes shrimp farming more sustainable by reducing the environmental impact and the incidence of shrimp disease. Antimicrobial peptides in the fish skin kill shrimp pathogens, keeping pathogen pressure of bacteria and viruses low. In polyculture, shrimps can eat tilapia faeces and unused fish feed, while tilapia filter phytoplankton, reducing the risk of low dissolved oxygen levels at night. In addition, shrimp bioturbation at the pond bottom returns nutrients to the water column, enhancing phytoplankton production and consequently the natural feed available for the tilapia. Biofloc technology (BFT) is one of the most applicable and promising systems for sustainable aquaculture development. This technology is essentially based on the recycling of nutrients via microorganisms, primarily (i) heterotrophic bacteria, which convert nitrogen compounds into microbial biomass, in addition to serves as a source of food for aquatic organisms, and (ii) chemoautotrophic bacteria, which convert ammonia to nitrite and nitrate.

The development of fishery-photovoltaic complementary industry and the studies on its environmental, ecological and economic effects in China: A review

The fishery-photovoltaic complementary industry is an emerging industrial model in China that integrates aquaculture with the solar industry. This innovative model involves conducting aquaculture activities while installing photovoltaic modules on the water surface to harness solar energy for electricity generation. However, despite its rapid growth in China, this model lacks substantial scientific data support across various domains. Therefore, based on an analysis of relevant research literature, this study reviews the current development status, environmental and economic effects, as well as challenges faced by the fishery-photovoltaic complementary industry in China. The aim is to provide scientific references for promoting sustainable development within this sector. The findings reveal that existing fishery-photovoltaic complementary industry projects are primarily concentrated in the middle and lower reaches of the Yangtze River and Pearl River Basin. The geographical distribution of these projects is predominantly influenced by local aquaculture areas and available solar energy resources, with a greater impact observed from the former rather than the latter. During summer months when water is shaded by photovoltaic panels, a slight decrease in the average water quality parameters across cases was observed, such as a decrease of 0.2 units in pH, a decrease of 1.06 °C in water temperature, a decrease in dissolved oxygen levels of 0.8 mg/L, inorganic nitrogen content and total phosphorus concentration dropped by 0.08 mg/L and 0.02 mg/L respectively. Conversely, there is a moderate increase noted in total nitrogen and ammonia nitrogen levels. The conclusion of the effect on phytoplankton biomass is not uniform, but it will certainly reduce zooplankton biomass. The impact on the species diversity of the zooplankton community was minimal, and its direction, whether positive or negative, varied depending on the specific aquatic ecosystem. A certain degree of shade is advantageous for the cultivation of shade-loving fish. Through the strategic deployment of photovoltaic panels and the implementation of scientific stocking practices, it is possible to achieve sustained levels of fisheries production. This model also can reduce an average of 978.6 tons of CO2 emissions per megawatt per year through energy production, thus achieving the combined goals of energy conservation and emissions reduction, and ensuring the profitability of power generation. Additionally, compared with the land utilization area of 3.66 hm2 per megawatt of traditional ground-mounted photovoltaics, fishery-photovoltaic complementary only requires 1.64 hm2, which can significantly save land resources by utilizing water surfaces, which mitigates the conflict between land use for agriculture and renewable energy installations. At the same time, research also pointed out that the existence of fishery-photovoltaic complementary will inevitably have some negative impacts on bird communities. Economic analyses indicate that while initial infrastructure costs and long payback periods pose challenges, the overall economic feasibility is promising, especially with governmental support and technological advancements. However, several challenges need to be addressed for further development: these include difficulties associated with infrastructure construction and initial costs, long payback periods; insufficient experience and technical support; as well as a lack of research on ecological and environmental impacts - particularly an urgent need for comprehensive life cycle assessments encompassing both environmental and economic aspects. Future research should focus on life cycle assessments, improved PV technology integration, and optimized aquaculture practices.

Characteristics of demersal fish community structure during summer hypoxia in the Pearl River Estuary, China.

In recent decades, hypoxic areas have rapidly expanded worldwide in estuaries and coastal zones. The Pearl River Estuary (PRE), one of China's largest estuaries, experiences frequent seasonal hypoxia due to intense human activities and eutrophication. However, the ecological effects of hypoxia in the PRE, particularly on fish communities, remain unclear. To explore these effects, we collected fish community and environmental data in July 2021 during the summer hypoxia development period. The results revealed that bottom-layer dissolved oxygen (DO) in the PRE ranged from 0.08 to 5.71 mg/L, with extensive hypoxic zones (DO ≤ 2 mg/L) observed. Hypoxia has varied effects on fish community composition, distribution, species, and functional diversity in the PRE. A total of 104 fish species were collected in this study, with approximately 30 species (28.6%) exclusively found in hypoxic areas. Species responses to hypoxia varied: species such as Sardinella zunasi, Coilia mystus, and Nuchequula nuchalis were sensitive, while Decapterus maruadsi, Siganus fuscescens, and Lagocephalus spadiceus showed higher tolerance. Within the hypoxia area, dissolved oxygen was the main limiting factor for fish community diversity. Functional diversity (FDiv) decreased with higher dissolved oxygen levels, indicating a potential shift in the functional traits and ecological roles of fish species in response to changing oxygen conditions. Further analysis demonstrated that dissolved oxygen had a significantly stronger effect on fish community structure at hypoxic sites than in the whole PRE. Moreover, other environmental variables also had significant effects on the fish community structure and interacted with dissolved oxygen in the hypoxia area. These findings suggest that maintaining sufficient dissolved oxygen levels is essential for sustaining fish communities and ecosystem health in the PRE. This study provides novel insights into the effects of hypoxia on fish communities in estuarine ecosystems and has significant implications for the ecological health and management of the PRE.

Ecological dynamics of Al-Chibayish marshes in southern Iraq: Insights into water quality, fish genetic affinity, and conservation implications

The aim of this paper is to comprehensively investigate and analyze the ecological dynamics of the Al-Chibayish Marsh. The study focuses on key environmental factors, aims to gain insight into the diversity and abundance of fish populations within the marsh, identifies dominant fish families, and assesses monthly changes in species composition. Two locations were chosen from among the Al-Chibayish marshes for this study, and three water samples were collected every month at every site, starting from March 2020 to February 2021. The mean water temperature recorded was 23.66 °C, while the salinity content exhibited variation over the study period. In July, the salinity content measured 4.34 g/l. Moreover, the pH ranged from 7.4 to 8.5. Dissolved oxygen levels exhibited seasonal variation, with an average value of 7.65 mg/l. The mean alkalinity value was 155.25 mg/l. Planiliza abu is the predominant species in terms of relative abundance, constituting 25.99 % of the total catch. Its percentages varied from 12.13 % in May to 46.74 % in December, with Alburnus sellal accounting for 19.07 % of the catch, with variations between 5.10 % in May and 30.99 % in June. Oreochromis aureus comprised 15.98 % of the total and fluctuated from 11.17 % in March to 20.27 % in January. Other notable species include Carassius auratus (13.10 %), Coptodon zillii (10.49 %), and Carasobarbus luteus (3.80 %). The H index exhibited variation over time, with values ranging from 1.25 in March to a peak of 2.99 in October. On the other hand, the J index also displayed temporal variability, with values ranging from 0.65 in April to 0.86 in August, while the D index showed changes as well, with values differing from 1.66 in March to 3.79 in January. Finally, based on these data, the ecosystem in the study area can be considered a fragile system.

Development of an Ecosystem Model Considering Sediment Redox Processes in Enclosed Water Bodies

This study investigates enclosed water bodies to understand the intricate interactions among physical, chemical, and biological processes. A one-dimensional model, integrating sediment and ecosystem components, was developed to analyze oxygen depletion, nutrient dynamics, and the influence of sediment organic matter on oxygen concentrations due to stratification. Oxygen and nutrient concentrations were derived by combining results from a one-dimensional vertical diffusion model with the ecosystem model. The dissolution, adsorption, and desorption of inorganic substances in bottom mud react differently under anaerobic and aerobic conditions, necessitating separate formulations for reduction and oxidation reactions in the bottom mud model. In Lake Biwa, Japan’s largest lake, dissolved oxygen levels have decreased despite regulatory efforts since the 1970s, prompting an investigation into the causes of oxygen-depleted water masses. The model was thus applied to examine oxygen consumption in Lake Biwa’s deep sediments, shedding light on anoxia in enclosed water bodies. This study emphasizes the significance of bottom sediments in water quality models and their implications for ecosystems. Furthermore, the adaptive nature of this model allows for its application in various water bodies, including freshwater reservoirs, lakes, and saltwater bays.

Analyzing the potential for Padina gymnospora cultivation in the coastal waters of St. Martin’s Island, Bay of Bengal, Bangladesh: Determining the fluctuations of physicochemical property across seasons and locations

Cultivating seaweed presents an opportunity to enhance the livelihoods of the inhabitants of St. Martin's Island inhabitants. This research investigates the suitability of the island's coastal waters for seaweed cultivation, taking into account variations in physicochemical factors in different seasons. The water temperature and salinity at various locations ranged from 24.22ºC to 27.64ºC and 23.8 to 33.76 psu, respectively. pH remained relatively constant throughout the year, fluctuating between 7.71 and 8.22. Dissolved oxygen levels were highest during the dry, cooler winter season (6.47±0.21 ppm) and lowest during the monsoon season (4.96±0.09 ppm). Electrical conductivity (EC) ranged from 39.00 mS/cm to 53.46 mS/cm, while total dissolved solids (TDS) varied between 20.35 and 27.90 g/l. Water clarity was at its peak during the dry, cooler winter season, averaging 4.14 meters. This investigation confirms the feasibility of year-round seaweed cultivation in the coastal waters around St. Martin's Island. In our study comparing cultivation methods for Padina gymnospora during the dry, cool winter season, the long-line approach resulted in a higher daily weight gain compared to the floating net method. This trend extended to growth rates by length, with the long-line method demonstrating a 5.09% daily growth and the floating net method showing 4.46%. However, net biomass production was 289.32 g/m² for the long-line method and 381.28 g/m² for the floating net method. Furthermore, the Cost-Benefit Ratio values for the long-line and floating net methods were 2.57 and 3.27, respectively. These findings affirm the viability of cultivating Padina gymnospora in coastal waters using the floating net method. Biodivers. Conserv. Bioresour. Manag. 2024, 10(1): 1-14

Mathematical modelling of dissolved oxygen levels in a multi-cage salmon farm

Dissolved oxygen concentrations were monitored at 12 points distributed over 3 depths in one out of six cages in an Atlantic salmon farm and compared to the output of a mathematical model using the advection-diffusion equation and a model of the salmon's oxygen consumption to estimate spatial oxygen distributions. The effects of oxygen consumption in neighbouring fish cages on the oxygen levels observed in the monitored cage were found to be significant, and several model variants modified to better represent the real system were tested. Position data from 8 fish in the cage equipped with acoustic telemetry tags was used to refine the model configuration.Results show that simulating the full farm with all cages improves model fit significantly over simulating a single cage only. Even better fit was achieved in a single cage model with ad hoc modifications, indicating that there are additional non-modelled effects that should be investigated further. This study establishes the oxygen model as a suitable tool for monitoring and forecasting of oxygen conditions in salmon cages, and gives indications about he accuracy and limitations of the model.

Tailored expression of ICCM cutinase in engineered Escherichia coli for efficient polyethylene terephthalate hydrolysis

Enzymatic depolymerization of PET waste emerges as a crucial and sustainable solution for combating environmental pollution. Over the past decade, PET hydrolytic enzymes, such as PETase from Ideonella sakaiensis (IsPETases), leaf compost cutinases (LCC), and lipases, have been subjected to rational mutation to enhance their enzymatic properties. ICCM, one of the best LCC mutants, was selected for overexpression in Escherichia coli BL21(DE3) for in vitro PET degradation. However, overexpressing ICCM presents challenges due to its low productivity. A new stress-inducible T7RNA polymerase-regulating E. coli strain, ASIAhsp, which significantly enhances ICCM production by 72.8 % and achieves higher enzyme solubility than other strains. The optimal cultural condition at 30 °C with high agitation, corresponding to high dissolved oxygen levels, has brought the maximum productivity of ICCM and high PET-hydrolytic activity. The most effective PET biodegradation using crude or pure ICCM occurred at pH 10 and 60 °C. Moreover, ICCM exhibited remarkable thermostability, retaining 60 % activity after a 5-day reaction at 60 °C. Notably, crude ICCM eliminates the need for purification and efficiently degrades PET films.

Assessing the impact of climate change on dissolved oxygen using a flow field ecosystem model that takes into account the anaerobic and aerobic environment of bottom sediments

AbstractThis study examines the potential impacts of climate change on Lake Biwa, Japan’s largest freshwater lake, with a focus on temperature, wind speed, and precipitation variations. Leveraging data from the IPCC Sixth Assessment Report, including CCP scenarios, projecting a significant temperature rise of 3.3–5.7 °C in the case of very high GHG emission power, the research investigates how these shifts may influence dissolved oxygen levels in Lake Biwa. Through a one-dimensional model incorporating sediment redox reactions, various scenarios where air temperature and wind speed are changed are simulated. It is revealed that a 5 °C increase in air temperature leads to decreasing 1–2 mg/L of dissolved oxygen concentrations from the surface layer to the bottom layer, while a decrease in air temperature tends to elevate 1–3 mg/L of oxygen levels. Moreover, doubling wind speed enhances surface layer oxygen but diminishes it in deeper layers due to increased mixing. Seasonal variations in wind effects are noted, with significant surface layer oxygen increases from 0.4 to 0.8 mg/L during summer to autumn, increases from 0.4 to 0.8 mg/L in autumn to winter due to intensified vertical mixing. This phenomenon impacts the lake’s oxygen cycle year-round. In contrast, precipitation changes show limited impact on oxygen levels, suggesting minor influence compared to other meteorological factors. The study suggests the necessity of comprehensive three-dimensional models that account for lake-specific and geographical factors for accurate predictions of future water conditions. A holistic approach integrating nutrient levels, water temperature, and river inflow is deemed essential for sustainable management of Lake Biwa’s water resources, particularly in addressing precipitation variations.

Sezonowa i przestrzenna zmienność jakości wody w systemie jezior Lumina-Rosu w delcie Dunaju w Rumunii

The main aim of the present scientific paper is to assess water quality of the surface water of various lakes located in the Lumina-Rosu interdistributary depression, Danube Delta, Romania. As specific objectives, the paper considered to spot the main potential sources of contamination and their environmental impacts on aquatic ecosystems. Equally, the purpose of the article is to emphasize the importance of monitoring the water quality of the Danube Delta, for preserving these unique natural water resources and their ecosystem services (fresh water, biodiversity, flood control, recreation, nutrient cycling, fishing and other traditional activities, ecotourism). Surface water samples collected from several control sections situated on the main tributaries and canals, as well as from lakes were investigated physically (To - C, EC - μS/cm, TDS - mg/L, turbidity - NTU units, TSS - mg/L) and chemically (pH - units, DO - mg/L, N-NO2- - mg/L, N-NO3- - mg/L, P-PO43-- mg/L, Chla - mg/L, SiO2 - mg/L, TOC - mg/L, SO42- - mg/L, S2- - mg/L, H2S - mg/L and synthetic detergents - mg/L). Generally, the hydro-physical-chemical characteristics and water quality assessment of the surface waters of the lakes manifest the combined effect of both processes occurred in the catchment (weathering, sediment supply and transport), as well as the in situ lake processes (photosynthesis, sediment mixing, biogeochemical cycling, evaporation, eutrophication, productivity changes). Overall, the physical and chemical characteristics of the sampling sites investigated at high waters of the Danube are quite similar to those measured at low waters. The differences that mainly occurred within the lakes are more related to the limnological variables and the local environmental conditions. Anyway, a significant seasonal variation was noticed in the lakes, during the dry period, when different physical and chemical characteristics appeared to be influenced by high air temperature, lack of precipitation, low water level regime, low dissolved oxygen level regime, all related to climate change effects etc. Moreover, the anthropogenic factor that left its mark on some physical-chemical characteristics of water should not be omitted either. However, the results obtained within this study did not show such alarming values as might have dangerous effects on the investigated aquatic environments. The water quality information within this case study may be used for improving the understanding of the water quality issues and to better coordinate and plan for future monitoring activities in and around the Danube Delta environment. The results will contribute to updating the existing database with relevant information for a sustainable future of the Danube Delta and in similar areas that are subjected to such environmental challenges.

Effect of activated carbon compaction on water filtration efficiency

Water contamination in rural Malaysian areas, mainly caused by logging activities leading to soil erosion and river pollution, presents a significant threat to water supplies. In response, a specialized activated carbon water filtering device was developed to target the absorption of organic molecules. The impact of compaction of activated carbon on water filtering efficiency was evaluated. Testing both compacted and uncompacted activated carbon filters with contaminated river water, the study utilized the Malaysia Department of Environment’s (DOE) water quality index (WQI) to assess filter effectiveness. The results revealed that water filtered through compacted activated carbon was clearer and less yellowish compared to the uncompacted counterpart. Moreover, the compacted filter showed higher dissolved oxygen levels, lower ammoniacal nitrogen levels, and a lower pH, resulting in a significantly higher WQI score of 80.4 compared to 78.8 for the uncompacted filter. Further analysis via an adsorption isotherm test demonstrated the superior ability of compacted activated carbon to absorb acetic acid, as evidenced by higher lines in the Freundlich isotherm model graphs. These findings emphasize the efficacy of compacted activated carbon in water filtration, advocating for its integration into filter construction to enhance water quality in rural regions.

A Study of Physico-Chemical Properties in the Sombrero and Orashi Rivers in the Niger Delta

This study evaluates the physico-chemical parameters in parts of the Sombrero and Orashi Rivers (Agba-Ndele and Ikiri) in the Niger Delta over three months (June to August 2024). Parameters were obtain from the down, mid and up stream, and determined based on standard oceanographic methods PHA, 2004. The surface water samples were collected at a depth of above 15-20cm dark coloured glass bottles measuring 250ml, were used for DO/BOD and water collected were also used for general purpose analysis. The results indicate that Agba-Ndele River exhibited higher turbidity (2.43–2.04 NTU), total suspended solids (3.41–4.12 mg/l), and biological oxygen demand (0.7–3.7 mg/l), alongside lower dissolved oxygen (3.3–7.07 mg/l) levels. In contrast, the Ikiri River displayed lower turbidity (0.80–1.86 NTU), total suspended solids (1.60–3.88 mg/l), and biological oxygen demand (1.5–2.1 mg/l), with higher dissolved oxygen levels (6.3–6.22 mg/l). Chemical oxygen demand ranged from 0.873–5.06 mg/l for Agba-Ndele and 0.813–4.42 mg/l for Ikiri. Both rivers had alkaline pH values (8.43–9.98), with electrical conductivity measuring 12.36–14.20 µs for Agba-Ndele and 4.56–12.99 µs for Ikiri. The result further showed that Nutrient analysis indicated phosphate levels of 5.582–6.740 mg/l for Agba-Ndele and 5.083–7.011 mg/l for Ikiri, while nitrate concentrations were 0.950–2.927 mg/l for Agba-Ndele and 1.373–3.469 mg/l for Ikiri. The findings indicate that both rivers face distinct water quality challenges, showing signs of stress from industrial activities, agricultural runoff, urbanization, and other anthropogenic activities. This research underscores the need for targeted water quality management strategies to safeguard these vital ecosystems and support community health and resilience in the Niger Delta.

Influence of water quality and seasonal variations on freshwater macroinvertebrate diversity and community structure in wastewater treatment ponds, Phetchaburi Province, Thailand

Wastewater originating from the Phetchaburi municipality undergoes treatment in a series of five distinct stages at the King’s Royally Initiated Leam Phak Bia Environmental Research and Development Project (LERD) in Phetchaburi province, Thailand. These stages involve a sedimentation (pond 1), three oxidation ponds (ponds 2 to 4), and a final stabilization pond (pond 5). These ponds serve as habitats for macroinvertebrates; consequently, their diversity and composition might be influenced by fluctuations in water quality and seasonal variations. The primary aim of this research was to analyze the diversity and species composition of macroinvertebrate communities concerning varying levels of organic contamination across the five wastewater treatment ponds at LERD. This investigation spanned three seasons: cold season (December 2019), rainy season (July 2020), and hot season (April 2021). The findings revealed that the diversity and species composition of macroinvertebrate communities displayed distinct alterations across multiple environmental gradients, especially identifying the significant influence of organic loading levels observed in ponds 1 to 5. The macroinvertebrate communities exhibited two distinct groupings, with the Chironomidae and Candonidae or ostracods prevailing prominently in ponds 1 and 2 (heterogenous environments). This prevalence was attributed to the high levels of detrital food and the robust resilience of chironomid larvae and ostracods to organic pollution, thriving even in environments characterized by low dissolved oxygen levels. Conversely, the prevalence of snails from the Thiaridae family in ponds 3 to 5 (homogenous environments) indicated improved water quality conditions, notably lower organic matter levels, and a higher dissolved oxygen content. In addition, the study identified seasonal variations in macroinvertebrates, likely influenced by the differing organic loading and environmental conditions. Thus, this research provided insights into the factors shaping macroinvertebrate communities in a wastewater treatment system.

Adsorptive removal of phosphate from aqueous solutions using FeCl3‐immobilized melamine‐formaldehyde‐urea resin

AbstractThe surplus phosphorus in aquatic environments trigger eutrophication, an irreversible pollution stage marked by the rapid growth of algae and water plants, a decline in dissolved oxygen levels, and the emergence of dead zones. To address this critical issue, this study focuses on the removal of phosphorus in form of phosphate from aqueous solutions. The research involves the synthesis and characterization of FeCl3‐immobilized melamine‐formaldehyde‐urea resin, an innovative adsorbent, its characterization through Fourier transform infrared spectroscopy, and the evaluation of its adsorption capacity based on Langmuir and Freundlich equilibrium models. The experimental adsorption data fits well with pseudo‐second order kinetic model. Optimal adsorption parameters are carried with batch adsorption technique for 60 min using 0.5 g of adsorbent at pH = 2, achieving 15.55 mg g−1 adsorption capacity, and conducting experiments with tap‐water samples to replicate real‐world scenarios. The research findings have the potential to advance sustainable wastewater treatment technologies and contribute to the mitigation of nutrient pollution in aquatic ecosystems, addressing a pressing environmental concern.