Freshwater Sources Research Articles

Mapping the Hydrogeological Structure of a Small Danish Island Using Transient Electromagnetic Methods

AbstractSmall island communities often rely on groundwater as their primary source of fresh water. However, the limited land area and high proportion of coastal zones pose unique challenges to groundwater management. A detailed understanding of the subsurface structure can provide valuable insights into aquifer structure, groundwater vulnerability, saltwater intrusion, and the location of water resources. These insights can guide groundwater management strategies, for example, pollution regulation, promotion of sustainable agriculture, establishment of coastal buffer zones, and re‐naturalization of land cover. Ordinarily, structural characterization relies on geological mapping and boreholes, however, such approaches can have insufficient spatial resolution to aid groundwater management. In this study, transient electromagnetic (TEM) methods are used to map the subsurface of a small, 13.2 km2, Danish Island. The approach successfully identified two previously unknown paleochannels, where the interface between Quaternary aquifer units and an underlying Paleogene Clay aquiclude had maximum depths of 100 and 160 m below sea level. Before this, the interface was assumed to be 15 to 25 m below sea level: therefore, these paleochannels present substantial potential groundwater resources. Resolving geological heterogeneity within the Quaternary deposits was less successful and future work will focus on addressing these limitations. Nonetheless, in several locations, evidence of saltwater intrusion was observed within the Quaternary units. This work demonstrates how TEM mapping can identify water resources, define aquifer boundaries, and aid water management decisions. Such approaches could be applied in other areas, particularly small islands, where similar groundwater challenges exist.

Persistence of Microcystin in Three Agricultural Ponds in Georgia, USA

Cyanobacteria and their toxins can have multiple effects on agricultural productivity and water bodies. Cyanotoxins can be transported to nearby crops and fields during irrigation and may pose a risk to animal health through water sources. Spatial and temporal variations in cyanotoxin concentrations have been reported for large freshwater sources such as lakes and reservoirs, but there are fewer studies on smaller agricultural surface water bodies. To determine whether spatiotemporal patterns of the cyanotoxin microcystin occurred in agricultural waters used for crop irrigation and livestock watering, three agricultural ponds on working farms in Georgia, USA, were sampled monthly within a fixed spatial grid over a 17-month period. Microcystin concentrations, which ranged between 0.04 and 743.75 ppb, were determined using microcystin–ADDA ELISA kits. Temporal stability was assessed using mean relative differences between microcystin concentrations at each location and averaged concentrations across ponds on each sampling date. There were locations or zones in all three ponds that were consistently higher or lower than the average daily microcystin concentrations throughout the year, with the highest microcystin concentrations occurring in winter. Additionally, microcystin patterns were strongly correlated with the patterns of chlorophyll, phycocyanin, and turbidity. The results of this work showed that consistent spatiotemporal patterns in cyanotoxins can occur in produce irrigation and livestock watering ponds, and this should be accounted for when developing agricultural water monitoring programs.

Tracing freshwater sources and particle discharge in Kongsfjorden: insights from a water isotope approach

Arctic fjords are inherently vulnerable to global warming, particularly because of the substantial freshwater influx resulting from the melting of glaciers. In this study, precipitation, river water, surface ice, and seawater samples from Kongsfjorden were collected to identify the main sources of freshwater. The dual water isotope (δ18O and δD) results and temperature–salinity profiles revealed that between 0% and 7% freshwater contributed to the fjord’s water. Furthermore, different freshwater sources for surface and deep water were identified by the dual water isotope analysis. Turbidity profiles confirmed the alter in particle discharge associated with surface runoff and subglacial discharge. Our study highlighted the sensitivity of water isotope analysis in elucidating the hydrological processes within the fjord system and demonstrated its potential for investigating the impact of meltwater on biological processes in the Arctic.

Antibiotic Concentrations Induce Morphological Changes and Increase Biofilm Formation in Multi-Antibiotic and Heavy Metal Resistant Kluyvera cryocrescens and Serratia fonticola

Water pollution is the biggest challenge that has rendered existing water resources unusable due to contamination with antibiotics and heavy metals. Antibiotics are often used to treat bacterial diseases. Heavy metals, on the other hand, are micro-pollutants that pose a threat to aquatic systems, especially when they accumulate in nature. Increasing pollution and the uncontrolled use of antibiotics have exposed bacteria to non-lethal concentrations (sub-MIC), potentially leading to resistance. In this study, Kluyvera cryocrescens and Serratia fonticola were isolated from a freshwater source and characterised. The resistance profiles of the isolates to 16 antibiotics and 8 heavy metals were determined, revealing that they are multidrug-resistant. The effects of sub-MICs (MIC/2 and MIC/4) of antibiotics on biofilm formation, siderophore production, and cell morphology of bacteria were analysed. It was found that at some sub-MIC values of kanamycin, tetracycline, meropenem, erythromycin, and clarithromycin, biofilm formation by K. cryocrescens increased. An increase in biofilm production was also observed in S. fonticola at sub-MIC values of imipenem, meropenem, ceftazidime, ciprofloxacin, and clarithromycin. Moreover, significant morphological changes were observed in both isolates following treatment with meropenem, ciprofloxacin, and ceftazidime. After treatment with meropenem, the typical rod-shaped (bacillary) morphology of the isolates shifted to a round (coccoid) form. In contrast, the bacteria developed into long filaments after treatment with ciprofloxacin and ceftazidime. These changes in the bacteria may favour the development of resistance and pose challenges for the prevention and treatment of diseases. Therefore, it is crucial to understand how sub-MIC levels of antimicrobial agents alter the virulence properties of bacteria.

Monitoring Groundwater Vulnerability for Sustainable Water Resource Management: A DRASTIC-based Comparative Assessment in a Newly Township Area of Bangladesh

Groundwater is a vital source of freshwater in our daily lives. Global and local groundwater quality are degrading due to rapid urbanization, human interference, and policy variations, which is prominent in developing nations like Bangladesh. The major purpose of this research is to analyze aquifer vulnerability in Bangladesh's north-central area using conventional and modified DRASTIC modeling. Seven influencing hydrogeological factors were employed to develop and integrate conventional DRASTIC modeling: soil media, net recharge, aquifer depth, aquifer media, topography, hydraulic conductivity, and influence of vadose zone, while land use and lineament density were used with them for modified DRASTIC modeling. The findings from four vulnerability analysis detected 29.56% (93.35 sq.km), 22.24% (83.12 sq. km), 28.52 (106.93 sq. km), and 37.6% (140.55 sq.km) of the study area as high to very high vulnerable zones for groundwater pollution. Lower groundwater depth, higher hydraulic conductivity, moderate to high groundwater recharge, dense lineaments, dense settlement, agricultural land, and inland waterbodies together might indicate a high vulnerability in the research area. The validation results based on EC and nitrate levels show that conventional (r = 0.884, p ≤ 0.01; r = 0.951, p ≤ 0.01) and modified DRASTIC models (r = 0.868, p ≤ 0.01; r = 0.840, p ≤ 0.01) have a stronger association with unconfined aquifers, than confined aquifers. Modification with both additional parameters showed more accuracy compared to the conventional one. Frequent monitoring of groundwater quality in high and moderately vulnerable zones is recommended for earlier detection and prevention of potential aquifer degradation.

Aquaporin channels in desalination: Mechanical properties and operational load analysis

The scarcity of freshwater sources and the global demand for drinking water have spurred researchers worldwide to develop new and efficient desalination and water purification technologies. One promising method is desalination using aquaporin (AQP) channels, which are highly regarded for their biocompatibility and exceptional desalination efficiency. However, there is limited information on the mechanical behavior of these proteins under operational loads and how they maintain their function and resilience over time. This research employs all-atom molecular dynamics simulation to calculate the mechanical properties of the channels at the nanoscale. It also uses the finite element method to analyze the behavior of channels in vesicles embedded in composite plates at the macroscale under operational loads and conditions. Our research shows that the force on vesicle walls changes considerably with applied pressure, peaking at 14 pN at 55 bar. This variability highlights the need to carefully assess the weakest parts of the nanochannels, especially the helices HB and H1, which are susceptible to high strain and possible unfolding under extended stress. The results indicate the force tolerance threshold of the subsystems, guiding the application of appropriate force conditions for optimal performance and long-term system maintenance. Beyond desalination systems, the findings offer useful information for researchers working with aquaporin nanochannels in applications such as targeted drug release systems based on protein nanovalves, solid-state sequencing systems, and more.

Nymphaea lotus Distribution in Oguta Lake: Implications for Heavy Metal Pollution in Surface Water and Sediments

Water quality is increasingly deteriorating and has affected lakes, which are important sources of freshwater. Heavy metals are of great concern because they are mostly toxic and resistant to decomposition. Aquatic macrophytes serve as stable biological filters that purify water bodies by accumulating dissolved metals and toxins in their tissues. Given their ability to trap various toxic heavy metals, the macrophyte Nymphaea lotus, which is observed on the surface waters of Oguta Lake, was studied to estimate the concentrations of six heavy metals in the water, sediment, and macrophytes. This was achieved by studying the spatial and temporal distribution of Nymphaea lotus in the lake and analysing the concentrations of heavy metals in the surface water, macrophytes, and sediment samples. Descriptive statistics, exploratory data analysis, and correlation analysis were used to analyse data obtained. Results revealed that the population of Nymphaea lotus declines over time from June to November in all regions. Upstream had the highest concentration of macrophytes (64%), while the downstream area has the lowest (2%). The heavy metal concentrations in the three samples ranges from 0.16 mg/kg to 2.96 mg/kg in sediments and Nymphaea lotus, and from 0.16 mg/L to 2.16 mg/L in water, with lead showing the highest concentration across all sample type. This highlights heavy metal contamination in the lake. The sparsely populated Nymphaea lotus exhibits selective bioaccumulation of lead, mercury, and zinc, while it seems to exclude or inefficiently absorb arsenic and chromium. Correlation analysis suggests a close interdependence between the concentrations of metals in sediments, water, and macrophytes, with sediments playing a key role in both water contamination and macrophyte metal absorption. Corrective and preventive measures should be taken to restore the lake.

Saltwater intrusion simulations in coastal karstic aquifers related to climate change scenarios

Coastal zones are crucial ecosystems supporting significant biodiversity and pertinent socio-economic activities. However, anthropogenic development contributes to socio-environmental complexities, particularly public water supply threats caused by climate change. This research presents a case study on the north-western coast of Yucatan, Mexico, which models potential saltwater intrusion in groundwater for multiple projections of sea level rise and recharge change due to climate change and its implications for the public water supply of the regional population and ecosystem. For this purpose, a previously calibrated and validated numerical model is employed, adapting its boundary conditions, keeping its calibrated hydrogeologic parameters, and considering the 2040 and 2100 climate change projections. Simulation results show that under these projections, significant saltwater intrusion may occur, reducing freshwater thickness due to increased salinity in groundwater and a loss of freshwater sources resulting from brackish-saline wedge intrusion. These scenarios are of particular concern as freshwater in this coastal region is the main source for public water supply and for freshwater input in coastal ecosystems. Moreover, this study underscores the susceptibility of karstic aquifers to salinization, especially in the face of rising sea levels, given their unique hydrogeological characteristics and substantial responsiveness to marine forcings. In spite of the uncertainties in global climate change predictions, this study enhances our understanding of the dynamics of these unique aquifers, and presents future saltwater intrusion projections that offer valuable technical insights to design and implement pertinent and resilient coastal aquifer management strategies.

Cytochromes b5 Occurrence in Viruses Belonging to the Order Megavirales.

Cytochrome b5 is a small electron transport protein that is found in animals, plants, fungi and photosynthetic proteobacteria where it plays key metabolic roles in energy production, lipid and sterol biosynthesis and cytochrome P450 biochemistry. Previously it was shown that a gene encoding a soluble and functional cytochrome b5 protein was encoded in the large double stranded DNA virus OtV2 that infects the unicellular marine green alga Ostreococcus tauri, the smallest free-living eukaryote described to-date. This single gene represented a unique finding in the virosphere. We now report that genes for soluble and membrane-bound cytochromes b5 also occur in giant viruses in the proposed order Megavirales, particularly the AT-rich Mimiviridae and Tupanviruses. Conversely, other members of the Megaviralestaxa such as the GC-rich Pandoraviridae have not been found to encode cytochrome b5 as yet. Megaviruses encoding cytochrome b5 have been isolated from the deep ocean, from freshwater and terrestrial sources, as well as from human patients. Giant virus cytochrome b5 proteins share high sequence identity with one another (45-95% depending on group) but no more than 25% identity with the cytochrome b5 gene product we identified in Acanthamoeba castellanii, an amoeba host for many giant viruses. Thus, the origin of the unique cytochrome b5 genes in giant viruses remainsunknown. Examination of viral cytochrome b5 primary amino acid sequences revealed that some have either a N- or C-terminal transmembrane anchor, whilst others lack a membrane anchor and are thus predicted to be soluble proteins. This cytochrome b5 topography suggests adapted biochemical functions in those viruses. Our findings raise questions regarding the evolution and diversity of cytochrome b5 proteins in nature, adding to questions about the origin of viral haemoproteins in general.

Groundwater Contamination by Heavy Metals in Malaysia: Sources, Transport, and Remediation Strategies

Groundwater contamination by heavy metals is a pressing environmental concern, particularly in regions highly dependent on groundwater as a freshwater source. While Malaysia primarily relies on river water, certain states and islands depend on groundwater for their supply. Research on heavy metal contamination in Malaysia’s groundwater remains limited, making it crucial to study the distribution and mobility of contaminants to develop appropriate remediation strategies. In addition to natural sources, anthropogenic activities such as landfills, mining, and the use of fertilizers contribute significantly to heavy metal pollution in groundwater. Factors like rainfall, fluctuating groundwater levels, and low soil pH can exacerbate heavy metal leaching into aquifers. Various models and techniques, including 2D resistivity imaging and MODFLOW, are used to assess groundwater flow and contaminant transport. These models suggest that contaminant concentrations decrease with increased depth and radial distance from pollution sources such as landfills and mining areas. The health risks associated with heavy metal exposure through groundwater consumption are significant, necessitating effective remediation strategies. Phytoremediation is an economical solution for groundwater containing low concentrations of heavy metals, while permeable reactive barriers may be suitable for more complex cases, pending detailed site investigation. This review aims to examine the current state of knowledge on heavy metal contamination in Malaysia’s groundwater, focusing on sources, distribution patterns, and movement of pollutants. It also seeks to evaluate existing remediation methods, including phytoremediation and permeable reactive barriers, while identifying gaps in research, particularly concerning risk assessments and heavy metal speciation.

Geological influence on groundwater quality in volcanic aquifers of Eastern Mount Cameroon, West of the Penda Mboko River

This study explores the utility of silica concentration in deciphering geological controls and hydrogeochemical processes affecting groundwater quality in Mount Cameroon’s volcanic terrain. Fifty water samples from wells, boreholes, springs, and rivers were analysed for hydrochemical properties (EC, pH, temperature, TDS) and major ion concentrations (Ca2+ > Mg2+ > K +> Na+ and HCO3− > Cl −> NO3− > SO42−). The groundwater exhibits low mineralization, with a dominance of Ca2+, Mg2+, HCO3−, and SiO2, reflecting minimal water–rock interaction and short residence times. Spatial variations in hydrochemistry suggest diverse water–rock interactions and potential mixing processes (76% of samples in rock dominance zone). Silica concentrations (5.8–58.7 mg/L) and estimated chalcedony temperatures (> 60 ℃ at five sites) indicated depths exceeding 1000 m. This research highlights silica’s effectiveness in tracking water–rock interactions across diverse geological settings, regardless of flow depth or interaction time variations. Mineral saturation indices pointed towards supersaturation with silicate minerals (quartz) but undersaturation with carbonates, sulphates, and halides. These findings contribute to a better understanding of groundwater evolution in Mount Cameroon, valuable insights into the hydrogeochemical processes shaping groundwater quality, aiding sustainable water resource management practices that can benefit local communities by ensuring a reliable source of freshwater. However, opportunities exist to improve future studies and water resource management. For a more comprehensive understanding, future analyses should include a broader range of geochemical tracers, such as nitrate (NO3−) and phosphate (PO43−), to assess potential agricultural or anthropogenic contamination. The study also found elevated levels of chloride and sodium, suggesting potential anthropogenic influences on groundwater quality, such as agricultural practices and waste disposal.

A preliminary study on detecting human DNA in aquatic environments: Potential of eDNA in forensics

Human environmental DNA (eDNA) application have not been fully applied or adequately considered in the fields of eDNA and forensics. Nonetheless, this technique holds great potential as a complementary tool for detecting human DNA in aquatic environments, particularly in cases involving crimes connect to such environments. However, the detectability or stability of eDNA can vary depending on several factors. Therefore, this preliminary study investigates the detection and degradation rates of human eDNA, as well as the recovery of nuclear short tandem repeat (STR) profiles and mitochondrial DNA (mtDNA) sequencing, using water samples from both saltwater and freshwater sources. To conduct the experiment, whole human blood was spiked into the water samples. Water samples were then filtered using a 5 µm pore size filter, and samples were collected at various time intervals up to 23 days. A human specific qPCR assay targeting HV1 region of human mtDNA was used to detect human eDNA. Results demonstrated that human eDNA remains detectable for up to 36 hours in freshwater samples and up 84 hours in saltwater samples. The limit of detection (LOD) of human eDNA, (205 copies/µl), was achieved after 60 hours in freshwater and 180 hours in saltwater samples. Partial STR profiles could be recovered up to 24 hours for freshwater and saltwater. Results from mtDNA sequencing indicate that full mtDNA profiles could be recovered from freshwater samples up to 48 hours and remained detectable up to 72 hours in saltwater. Overall, the findings of this study underscore the importance of considering and incorporating human eDNA analysis as a valuable tool in forensic practice. By harnessing the power of eDNA, law enforcement agencies can enhance their investigation capabilities, improve the accuracy of forensic reconstructions, and ultimately contribute to the resolution of cases involving aquatic environments. Further research and validation are needed to optimize and expand the utilization of eDNA techniques in forensic investigations.

Growth performance, blood health, and antioxidant status of freshwater carp under brackish water rearing system: Sustainable aquaculture approach in arid and semi-arid conditions

Global warming, water salinization, and increased anthropogenic usage of freshwater sources have had severe effects on water sources and aquaculture practices, which is consequently putting pressure on aquatic fauna and fish production. Hence, brackish water can be used as an alternative and sustainable approach to meet the increasing food requirements. Four groups with triplicates were designed to evaluate the impact of brackish water on Cirrhinus mrigala (n = 100) for 180 days; T0: control group (freshwater), T1: (5.45 ppt salinity), T2: (8.45 ppt salinity) and T3 (12.45 ppt salinity). Little behavioural alterations and normal feeding were observed in all experimental groups as compared to control group, except group T3. Survival rate was 100 % in all groups excluding group T3, which had shown 88 % survival rate (P < 0.05), while mean weight gain and length gain were observed better with low FCR in T1 and T2 groups (P < 0.05) but best growth rate observed at 5 ppt salinity level. Significant reduction in haemoglobin (Hb), hematocrit (HCT), red blood cells (RBCs) and increase in white blood cells (WBCs) and platelets (PLTs) was observed in group T3 compared to other experimental groups (P < 0.05). ALT, AST, ALP, urea, creatinine, and triglycerides, exhibited significant changes in T3 group after 180 days (P < 0.05). Erythrocytes had shown morphological alterations as; micronuclei, notching, blebbing, pear-shaped nuclei and spherocytes in T3 group. Significant increase in DNA damage in various tissues had indicated potential genotoxic impact of highly saline brackish water. Oxidative stress markers were increased significantly and antioxidants reduced (P < 0.05) at high salinity level brackish water (T3) until 180 days. In conclusion, C. mrigala can potentially grow well in brackish water system at 5 ppt salinity whereas, rise in salinity level (12 ppt) is detrimental to freshwater fish health and growth.

Phytoplankton morphological traits and biomass outline community dynamics in a coastal ecosystem (Gulf of Trieste, Adriatic Sea)

AbstractTrait-based ecology has recently gained increasing importance in phytoplankton research. In particular, the taxonomic and morphological traits, such as size and shape of phytoplankton cells, can help to unveil the ecological processes and their drivers in the pelagic domain. Our study aims to shed light on the trophodynamics of phytoplankton communities in a coastal ecosystem in the northern Adriatic Sea (Gulf of Trieste) using data on individual traits such as biomass, size and shape of phytoplankton taxa during a one-year study. The phytoplankton parameters were investigated at the levels of the whole community, groups, and individual cells, analysing also the probability distributions of biomass and size of the latter level. The results showed good agreement between abundance and biomass data, as well as individual size and biomass with differences partly explained by cell shapes. We have emphasized the role of the local freshwater source in bottom-up control, alternating with top-down control of phytoplankton dynamics through taxonomic and morphological diversity. The predominant bimodal and non-power law distribution, especially during and around the biomass peaks, confirmed the importance of nano- and microphytoplankton size classes and the role of blooms in destabilizing the trophic webs. We suggest that the analyses of distribution types of individual cell size and biomass can be appropriate to spot ecological processes driving to unconstrained phytoplankton proliferation or to periods of trophic web stability.

Design and implementation of closed-loop water reuse systems in urban and industrial settings for maximizing resource recovery and minimizing waste

Global demand for water while the freshwater sources are diminishing, it is necessary to find feasible solutions based on sustainable usage of resources. The goal is to provide beneficial use of as many resource constituents as possible with as little effluent discharge as possible leveraging innovations in treatment technologies and systems. Parameters of discussion include the operation and efficiency of membrane bioreactors, different kinds of oxidation, and reverse osmosis technologies. Such technologies are instrumental in improving the quality of water as well as enabling recovery of useful resources from the streams of wastewater that are normally obtained from several processes. This paper also assesses the feasibility of resource recovery closed-loop systems to measure its economic benefits determinable by operational expenses, energy usage and possible revenue streams from the recycled materials. Such knowledge synthesizes the findings of prior studies in the literature and emerging technologies that help to support this research and identify the impact that closed-loop water reuse systems can have. This emphasizes on the need to have proper regulatory status and consumer’s involvement for its general adoption and practicable implementation. In the long run, the integration of the systems explained above will definitely advance a sustainable water management system that will help in the stewardship of the environment and ensure that in case of arising challenges globally the country will be able to cope.

Design of wastewater treatment unit using End-of-Life (EoL) Reverse Osmosis membrane

Abstract Sultanate of Oman is facing severe challenges due to water scarcity, shortage of rainfall, and limited freshwater resources. Over the past few decades, 90% of the natural water resources are consumed by agriculture. Hence, there is an urgent need to find an alternative to obtain fresh water. Water desalination by Reverse Osmosis (RO) is currently practiced in Oman as freshwater source, since it contributes 80% of the total desalination plants installed worldwide. The RO process results in environmental concerns triggered by emission of gases, and discharge of Reverse Osmosis (RO) membranes. The lifespan of membranes depends on the water quality and the operating conditions, and the membrane life is estimated as 5 to 10 years. In order to mitigate the environmental impact for a sustainable desalination output, reuse of discarded end-of-life (EoL) RO membrane is a feasible solution to enhance the water quality. The efficiency of RO membranes is affected by the fouling, scaling, and chemical cleaning for the yearlong operation which lead to reduced salt rejection rate. Hence, this research aimed to reuse the old RO elements by transforming them into Ultrafiltration unit (UF) by removing the active layer and increasing the pore size of membrane. Additionally, modifying the membrane by open configuration and separating all 28 membrane sheets from the permeating tubes are designed as RO-MBR panels. The study shows that, after 5 weeks of operation, the average turbidity rejection rate was 94%, and the average permeated flux per unit was 6.9 LMH. The new configuration shows the permeate flux stability and acceptable BOD, and COD reduction.

Experimental study based on the usage of polymers for greywater treatment

Water scarcity presents a pressing challenge in Egypt, exacerbated by factors such as population growth, urbanization, and climate change impacts. With over 95% reliance on the Nile River for freshwater supply, Egypt's water resources are strained, particularly with a population exceeding 100 million. Egypt's arid climate intensifies water scarcity, necessitating sustainable management strategies. This study explored greywater treatment as a solution to alleviate water scarcity in Egypt, investigating its technical feasibility, economic viability, and environmental benefits. Greywater, derived from domestic activities, is an underutilized resource that can be reclaimed and treated for reuse, reducing demand for freshwater sources. Through greywater treatment systems, households and communities can recycle water, conserve resources, and mitigate pollution. The study investigated using polymers as a coagulant in greywater treatment, examining its efficacy in removing contaminants and improving water quality. Experimental trials were conducted to evaluate the performance of polymer addition in greywater treatment compared to conventional methods. Results demonstrate that polymer addition reduces turbidity, suspended solids, and organic pollutants in greywater. Poly aluminum chloride (PAC) polymer, in particular, exhibits strong coagulation capabilities, versatility across pH ranges, and high efficiency in contaminant removal. Additionally, PAC offers operational advantages such as low dosage requirements and reduced sludge production.

Spatial Distribution of Groundwater Fluctuation Mapping Using Arc-GIS in Hosur-1 Micro-watershed of Karnataka, India

Groundwater is a primary source of freshwater and used mainly for agriculture and irrigation purposes. Recharge to groundwater is the most important component in all the water balance studies. In the present study krigging technique was used for interpolate the groundwater level of the Hosur-1 micro watershed (Kanakvad sub watershed) in Gadag district of Karnataka state. In Hosur-1 micro- watershed 41 wells are there in the vicinity of major stream of the micro- watershed. The mean depth of ground water levels in the micro- watershed were monitored at a monthly frequency during January-2023 to March-2024. It was found that the maximum average depth of bore wells are about 9.55 mts and lowest average depth of borewell about 4.64 mts. The groundwater table between 2.48 to 14.70 mbgl during summer season period and 3.18 to 21.50 mbgl during the Rabi season. The pH of ground water varied between 7.0-9.0, maximum pH was recorded as 8.9 and minimum was recorded as 7.29 and maximum conductivity &gt;3.82 ds/m and minimum 0.87 ds/m was recorded at Hosur-1 micro-watershed. The average infiltration rate of clay soil 2.73 mm/hr and R2 value for the trend line reaches the value of 0.5876. In case of sandy clay loam average infiltration rate was 3.83 mm/hr and R2 value for the trend line reaches 0.6572. It necessitates continuous monitoring of groundwater for assessing the possible damage on salinity and alkalinity induced soil health.

Influence of altered freshwater discharge on the seasonality of nutrient distributions near La Grande River, northeastern James Bay, Québec

In subarctic marine environments, nutrient stocks are replenished through physical and biogeochemical processes in winter, largely setting an upper limit on new primary production for the next growing season. In spring, marine nutrient stocks are modified by freshwater-associated additions, especially in coastal areas. Hydroelectric development of the La Grande River (LGR) in northern Québec has shifted the timing of peak freshwater discharge from spring into winter, producing 10 times the natural winter discharge. Here, we considered salinity, oxygen isotope ratio (δ18O), and nutrient (nitrate, phosphate) data from coastal waters of northeast James Bay in different seasons of 2016 and 2017. We quantified two main freshwater sources, LGR and sea-ice melt, established by freshwater tracers, and their influence on coastal nutrient distributions. Our results show that LGR is the dominant source of freshwater to coastal waters throughout the year, especially during winter, and an important source of nitrate to nitrogen-limited coastal waters (winter concentrations of 4.53 μM versus 3.18 μM in ambient seawater). Despite being a poor phosphate source (0.11 μM versus 0.66 μM in ambient seawater), LGR provides the largest portion of the phosphate stock in surface waters near its mouth. LGR regulation has changed the pattern of natural fluvial nitrate inputs: what was observed in spring (pre-development) is now observed in winter (post-development). Thus, high winter surface nitrate stocks (22.5 mmol m−2) are available to support primary production, but are dispersed to offshore areas prior to the onset of the growing season, which begins only after the return of light. In northeast James Bay, the timing and magnitude of primary production, dependent on nutrients in the water column, is expected to have been impacted by altered freshwater input, reducing overall production in local areas and potentially increasing production further downstream with cascading effects on the marine ecosystem.

Biofilms on urban aquatic plastic pollution as a reservoir for pathogenic yeasts

ABSTRACT Pollution of aquatic environments is a concern and poses a health risk to aquatic and terrestrial life. Plastic pollution acts as surfaces to which microorganisms adhere, forming a community known as the plastisphere. Studies investigating the bacterial diversity of the plastisphere are plentiful, but less is known about the fungal communities, especially yeasts, within these biofilms. Given the increasingly recognised threat of yeast infections, it is important to investigate the environmental presence of potential pathogenic yeasts on possible vectors that may contribute to their distribution. In this study, the fungal diversity of the plastisphere of various types of plastic polymers collected from an urban freshwater source was analysed, and possibly pathogenic yeast strains were identified. Isolates were also tested for susceptibility to the antifungal, fluconazole. Microscopic analysis shed light on the overall diversity found in the plastisphere, while metagenomic data revealed that fungal plastisphere communities are dominated by the phylum Ascomycota. Both metagenomic and culture-dependant analysis revealed the presence of possibly pathogenic yeast in the genera Candida (some with low fluconazole susceptibility) and Exophiala. This highlights possibilities that the plastisphere may harbour pathogenic yeasts and could contribute to their distribution in the environment and transmission between the environment and humans.