Water Sources Research Articles

Risk Factors Associated with Increased Toxoplasma gondii Seroprevalence in South Australian Sheep

Toxoplasma gondii (T. gondii) is a protozoan parasite of substantial impact to small ruminants, with reproductive failure a possible outcome of exposure. This observational study assessed T. gondii prevalence within the South Australian sheep population and investigated on-farm risk factors to T. gondii exposure via a cross-sectional survey. 1433 individual animals, consisting of 1282 mixed-age ewes and 151 mixed-age rams were blood sampled and serologically screened for T. gondii-specific antibodies. A risk-analysis questionnaire was conducted for each participating property. Of the 1433 animals sampled, 530 tested positive, with seroprevalence observed to be 39% (95% CI 28.7% to 49.3%) after accounting for clustering within properties. All properties returned at least one positive result, indicating a flock level seroprevalence of 100%. T. gondii seroprevalence was found to be higher in sheep on Kangaroo Island (46.6%; 95% CI 32.1% to 61.1%) compared to the South Australian mainland (31.3%; 95% CI 18.4% to 44.2%), however this difference was not statistically significant (P=0.125). A significant association was observed between T. gondii seroprevalence and age, with seroprevalence increasing from 30.2% (95% CI 17.7% to 42.6%) in one year old sheep, to 69.7% (95% CI 47.0% to 92.5%) in sheep older than six years (P=0.001). T. gondii seroprevalence was significantly higher in animals drinking water from surface water sources (55.9%; 95% CI 35.2% to 76.6%), compared to those exclusively sourcing reticulated mains water (19.1%; 95% CI 0%-39.0%) (P=0.028). An individual animal exposed to a surface water source was found to be more than ten times as likely to be exposed to T. gondii, than an animal sourcing only reticulated mains water (odds ratio:10.68; 95% CI 1.30 to 87.88). Water source is important in the transmission of T. gondii to South Australian sheep. Mitigation strategies should be developed and targeted at reducing contact between oocysts and water sources and reducing interaction between livestock and contaminated water.

Analysis of Nanobubble-oxygenated Water for Horticultural Applications

The theoretical properties of nanobubbles (NBs), such as a negative surface charge and large interfacial surface area, allow for highly efficient gas transfer and stagnation time in water and may reduce the surface tension of NB-treated water sources. These properties make NBs unique candidates for addressing issues like root zone oxygen deficiency, common in conventional and hydroponic crop production. Therefore, the objectives of this research were to confirm the presence of NBs in treated water and determine how time and temperature affect dissolved oxygen (DO) retention in NB-oxygenated water. Two membrane-based NB injection systems were compared with a standard method of aeration (aquarium air stone) and untreated potable water to determine the effect of NB oxygenation on DO retention time and nanoscopic particle size and concentration of potable water sources. NB oxygenation of potable water generally resulted in a greater number of nanoparticles detected compared with untreated potable water. NB oxygenation increased initial levels of DO in potable water when compared with the standard air stone. NB oxygenation failed to increase DO retention time compared with a standard air stone, regardless of water temperature. NB oxygenation remains a method of efficiently oxygenating large volumes of water, although the NBs investigated in the study did not increase DO retention in a potable water source.

From thaw till fall: Interacting hydrology, carbon cycle, and greenhouse gas dynamics in a subarctic stream-lake continuum.

Carbon-water interaction studies between aquatic and terrestrial ecosystems are especially needed today in Arctic and Boreal regions, as they are facing drastic warming and precipitation shifts. Despite the importance of streams in the carbon cycle, northern stream-based studies are scarce, owing to a lack of measurements throughout the north, and possibly skewing global greenhouse gas estimates. We used a combination of multiscale measurements to quantify water sources (H2O isotope proxies), carbon availability (dissolved in/organic carbon concentrations) and quality (water absorbance, SUVA254 -index), microbial community structure (16S rRNA sequencing), and carbon dioxide (CO2) and methane (CH4) fluxes and concentrations. Our study site comprises a groundwater-influenced and peatland-dominated second-order stream, along with its adjacent lake inlet located in Northern Finland. Sampling was conducted three times during the summer of 2019 at 21 locations along the stream-lake continuum. Temporal and spatial shifts in water sources altered carbon characteristics, with CH4 concentrations being the key environmental factor shaping the microbial communities, overriding the influence of dissolved organic carbon amount and quality. The prevalence of methanotrophic bacteria highlighted the importance of CH4 as a carbon source and the methanotrophic groups as drivers of the CH4/CO2 source-sink attributes of subarctic stream systems. Our results highlight the value of integrated hydrological, biogeochemical, and microbiological measures to resolve the biocomplexity of carbon-water interactions in northern headwater catchments.

Mapping key areas to protect high-value and high-vulnerability groundwater from pollution load: Method for management.

Severe groundwater pollution has necessitated prioritizing the prevention and control of groundwater pollution (PCGP). The fundamental strategy of PCGP involves identifying priority areas. Vulnerability assessment, such as DRASTIC, and its extension, pollution risk assessment, have been developed to guide PCGP. However, managers find it struggling to implement these results in PCGP due to a lack of consideration for practical management demands. This study establishes a management-oriented method to map key areas for groundwater protection and PCGP, considering water sources, pollution source load, vulnerability, and function value, to facilitate management implementation. The key area includes the protection area aimed at protecting water sources and the control area focused on preventing and controlling pollution load in high-value and high-vulnerability groundwater. The effectiveness and practicality of this method are demonstrated through a case study in a large district reliant on groundwater, enabling the key area and corresponding suggestions to directly guide local management. This method offers a practical tool for PCGP worldwide and is expected to guide the sustainable development plan.

A multi-dimensional comparative study on the performance of algae removal using various flotation

Flotation is considered the most cost-effective and efficient algae-water separation technology. However, there are various flotation techniques for algae removal, such as coagulation-flotation (CF), foam flotation (FF), and positively charged bubble flotation (PF). It remains unclear which method is most suitable for removing algae from water bodies and under what specific conditions each technique is most effective. This study systematically compares CF, FF, and PF in terms of algal cell removal efficiency, concentration ratio, flotation kinetics, impact on algal cells, removal efficiency of algal organic matter (AOM) and microcystins (MC-LR), as well as economic cost analysis. CF is better suited for algae removal in water bodies, including drinking water sources, using fixed installations on shore due to its high removal efficiency, high concentration ratio, low chemical dosage, and minimal residuals. FF is more appropriate for non-drinking water sources as it can remove algae and further control algal growth; however, its residual CTAB may pose a threat to drinking water safety. PF is most suitable for in situ algae removal within water bodies, primarily because it does not require stirring or coagulation. Instead, modified bubbles can be directly introduced into the algal distribution layer, where they adhere to algal cells, facilitating algae-water separation. All three flotation methods are economically feasible for algae removal. For FF, the costs of chemicals and electricity are nearly equal, while for CF and PF, the primary cost is electricity. This study provides data to support the selection of appropriate flotation technologies for emergency removal of algal blooms in water bodies.

Comprehensive analysis of water and sediment from holy water body ‘Pokhri’ reveals presence of biomolecules that may educe skin, gastroenterological and neurological dysfunction

‘Pokhri mai’ refers to the natural pond amidst the hilly forest slopes of the Buxa tiger reserve (BTR) nearby Jayanti considered to be sacred by the local ethnic groups serving as the prime source of water for wild animals and occasionally by neighbouring inhabitants. However, the water body is designated to be noxious by a group of native people with no scientific validation. This paper focuses to explore its toxicity status and allied environmental concerns through Pokhri water and sediment sample analysis through physicochemical assessment, in vitro antioxidant assay, microbiological investigation followed by AAS, GC–MS and in silico study. pH of soil and water samples were found to be quite high (>6.8) with organic matter, carbon and available nitrogen content being 1.5308 ± 0.28 %, 0.89 ± 0.17 % and 0.072 ± 0.34 % respectively. Profuse microbial growths were observed in both sediment and water samples with consortia obtained exhibiting tolerance against a range of antifungals and antibiotics. Inhibition zone was absent for sediment consortium whereas consortium of water samples portrayed susceptibility against various heavy metals viz. Cu2+, Pb2+, Zn2+, Fe3+ and Al3+ salts with corresponding AAS quantified values of sediment samples being 133, 223.3, 86.8, 1449 and 481.5 ppm. A summative of 18 metabolites were identified by GC–MS in Pokhri lake sediment among which 13 (occupying 96.35 % peak area) were investigated to be potentially toxic with 2,4-Di-tert-butylphenol (53.38 %) as the major compound. Biomolecular characterization, ADMET test and molecular docking study with dermal, gastrointestinal and neural peptides exhibiting high binding affinity scores (ranging between −2.6 to −8.3 kcal/mol) further affirmed the toxicity attributes of the GC–MS deciphered molecules. The findings clearly justifies the local ‘myth’ of Pokhri water to be deleterious with prospective dermatotoxic, neurotoxic and being evident of gastrointestinal toxicity emphasizing ecological risk to the environment, wildlife and microflora of the adjoining forests.

Spatial analysis of environmental sanitation and stunting incidents

Environmental factors such as sanitation and hygiene, drinking water sources, quality of drinking water, and ownership of latrines are indirect factors causing stunting. This study aims to analyze the distribution of stunting and environmental sanitation factors that cause stunting in Dairi District, North Sumatra, Indonesia. The case-control design was carried out with 172 toddlers. The distribution pattern of stunting and the association of patient characteristics and environmental risk factors was carried out using the Geographic Information System. Data on healthy clean-living behavior was collected using a questionnaire, and microbiological laboratory tests measured water quality. The spatial analysis uses an average nearest-neighbor overlay. The association of characteristics and risk factors with the incidence of stunting was analyzed using chi-square and logistic regression. The average nearest neighbor analysis shows that the nearest neighbor index is 0.19 ( 0.05) are unrelated to stunting. The pattern of distribution of cases tended to be in clusters, and no relationship was found between population density and the incidence of stunting. The findings of this study provide a new understanding that health promotion to prevent stunting does not only focus on fulfilling nutrition but also on healthy clean-living behavior and water quality.

Enhancing Water Circularity: Lactic Acid-Menthol Deep Eutectic Solvent for Efficient Fats, Oils and Grease (FOG) Removal and Recovery from Contaminated Waters

Water pollution, particularly the contamination of water sources by fats, oils, and grease (FOG), presents a significant environmental challenge exacerbated by climate change. While conventional water resource recovery facilities (WRRFs) address various contaminants, FOG treatment often remains indirect and suboptimal. This study introduces an innovative, environmentally benign approach utilizing deep eutectic solvents (DESs) for the targeted removal and recovery of FOG from contaminated waters via liquid-liquid extraction. A binary DES comprising menthol and lactic acid was synthesized and evaluated for its efficacy in extracting oleic acid, selected as a model fatty acid contaminant. The investigation employed a comprehensive factorial design to optimize key operational parameters, including the molar ratio of DES components, solvent-to-water ratio, contact time, initial contaminant concentration, stirring speed, and phase separation time. Results demonstrated exceptional removal efficiencies exceeding 95% under optimized conditions, with peak performance approaching 99.5%. Optimal parameters were identified as a 1:1 molar ratio of menthol to lactic acid, 1:10 DES-to-water ratio, 15-minute contact time, 300 mg L⁻¹ initial contaminant concentration, 500 RPM stirring speed, and 8-hour phase separation. This research establishes a foundation for the application of DESs in water decontamination processes, potentially revolutionizing FOG management and advancing water circularity initiatives. The study's findings align with multiple UN Sustainable Development Goals, including SDG 6 (Clean Water and Sanitation), SDG 14 (Life Below Water), and SDG 12 (Responsible Consumption and Production), offering a promising avenue for sustainable water treatment technologies.

Sonocatalytic degradation of furazolidone using a heterogeneous triple ion synergy system of ZnFe2O4@ZIF-67 nanostructures: Physicochemical Characterization and degradation pathway

Heterogeneous sonocatalysis coupled with peroxydisulfate (PDS) activation is considered as a rapid advanced oxidation process for the degradation of emerging pharmaceutical pollutants. ZnFe2O4@ZIF-67 nanostructures (NSs) with commendable features including a high crystallinity, a narrow bandgap, and an outstanding specific surface, showed excellent sonocatalytic performance, PDS activation and stability. A novel triple ion synergistic system was used for the swift degradation of 60 mg/L furazolidone (FZD) from real contaminated water sources. A superior sonocatalytic degradation performance of FZD (94 %) by ZnFe2O4@ZIF-67/PDS/Ultrasound system was achieved under the optimal conditions of 20 mmol/L PDS and 0.4 g/L of the nanocomposite within 60 min. The e-/h+ pairs produced as a result of the sonoluminescence phenomenon in the ZnFe2O4@ZIF-67 NSs, with a bandgap of 1.86 eV, accelerated the redox reduction transform cycle of the Zn2+ /Zn, Fe3+/ Fe2+ and Co3+/ Co2+ pairs by generating a large number of oxidative radicals, leading to the enhanced degradation efficiency. Quenching tests illustrated that SO4•-,1O2, •OH radicals and surface oxidation–reduction reactions played a crucial role during FZD degradation. FZD degradation by-products were put forward using the LC-MS technique, and a plausible degradation pathway was suggested. The mineralization tests and the toxicity of generated intermediates of FZD degradation were also examined. Also, the stability and reusability results underscored the substantial proficiency of the above system to remediate real-pharmaceutical-contaminated-water sources, providing a practical approach for its industrial applications.

Visible light photocatalytic reduction of Toxic Chemical Organophosphate Monocrotophos using reduced Graphene Oxide derived from bamboo leaves

In this study, graphene oxide (GO) was synthesized from waste bamboo leaves using a pyrolysis and ultra-sonication technique. UV-visible spectroscopy revealed a prominent absorption peak at 230nm, while Raman spectroscopy confirmed the presence of characteristic D-band (1340cm⁻¹) and G-band (1596cm⁻¹). XRD analysis showed a peak at 11.5°, corresponding to a lattice spacing of 3nm, and SEM/TEM imaging demonstrated the formation of multi-layered graphene sheets. The synthesized GO was evaluated for the photocatalytic degradation of the organophosphate pesticide monocrotophos under visible light. At a concentration of 25mg/L, graphene exhibited a removal efficiency of 98% with a degradation rate of 0.036 ppm/min, following a Langmuir isotherm and pseudo-first-order kinetic model. The significance of this study lies in the potential environmental application, offering an economical and sustainable solution for the decontamination of pesticide-contaminated water sources. The method could contribute significantly for reducing environmental pollution and addressing global water safety challenges.

Causes for overestimation of the moisture recycling in an alpine meadow ecosystem of the Shule River Basin, Tibetan Plateau, China

Terrestrial moisture recycling is an essential hydrological component and a significant source of the atmosphere’s humidity budget in arid and semi-arid inland regions. Investigations on moisture recycling using the stable hydrogen and oxygen isotopes is currently a focal point in hydrologic research. However, the direct quantification of recycling ratio based on isotopic composition of evapotranspiration vapor is lacking. So, this causes challenges to compare studies, based in the same region and time period but with different methodologies. In this study, we measured the isotopic compositions of evapotranspiration vapor (δ18OET/δDET) from June to September 2018 in an alpine meadow ecosystem at the Shule River Basin by combining the Keeling plot model and in-situ chamber measurement. Using this data, the moisture recycled rate (mrr) was assessed based on the two-component (Model A) and three-component isotopic mixing models (Model B), respectively. Based on Model A and δ18OET, the analysis revealed that the mean recycled rate for the entire observation period was 35 %, while it was 26 % during the westerly period (the months dominated by the north branch of prevailing westerlies) and 44 % during the monsoon period (when subtropical moisture from the Indian monsoon penetrated the region). The recycled rate based on Model A and δDET was slightly larger with a mean value of 41 % during the entire observation period. The recycled rate based on Model B was also significantly higher in comparison with Model A, while the causes for this difference could be the assumption of substituting xylem water for transpiration vapor and the plant water source δD offset. The contribution of recycled moisture was notable lower for heavy rainfall comparing with light rainfall. Our findings provided a new perspective for the investigations of alpine meadow ecosystem hydrological processes.

The use of E. coli phylogrouping and microbial source tracking (non-species specific, human-specific, bovine-specific Bacteroidales markers) to elucidate hydro(geo)logical contamination mechanisms in southeastern Ontario, Canada

In Ontario, monitoring, maintenance, and treatment of private drinking systems (e.g. wells) are the responsibility of the well owner. Fecal contamination of drinking water threatens public health, particularly in rural communities which are often fully reliant on unregulated private groundwater as a primary drinking water source. Private well users face a higher risk of acute gastrointestinal illness compared to those served by municipally operated systems (Murphy et al., 2016). Accordingly, the current study sought to characterize the fecal indicator, E. coli, isolated from southeastern Ontario private groundwater wells, including phylogroups and host source. Results were examined in the context of antecedent climate and local hydrogeological setting to elucidate likely contaminant sources and pathways. A total of 737 E. coli isolates from 260 private wells were assigned to phylogroups using the Clermont PCR phylotyping method, with likely host source determined using host-specific Bacteroidales 16S rRNA RT qPCR assays. Multivariate models were developed for the main E. coli phylogroups (A, B1, B2, and D) and all microbial source tracking markers. Models were coupled for interpretation where possible, based on associations between phylogroups and MST markers. Preferential subsurface flow, and to a lesser degree, overland flow, were likely mechanisms of contamination across all models. Distinct temporal associations were found based on the fecal source. Multiple models were developed and will be discussed, in an attempt to elucidate source-specific contamination mechanisms, in support of risk assessment and appropriate protective actions.

Silica-coated nano zero-valent iron as a slow-release electron donor for sustained enhancement of aerobic denitrification in oligotrophic source water: Performance and mechanism

Limited organic carbon in drinking water constrains the removal of nitrate‑nitrogen (NO3−-N) via aerobic denitrification. This paper reports the use of silica-coated nano zero-valent iron (nZVI@SiO2) as a stable and sustainable electron donor to enhance aerobic denitrification. The nZVI@SiO2, synthesized via a one-step method, was resistant to oxidation and exhibited excellent stability. In conjunction with aerobic denitrifying bacteria, nZVI@SiO2 achieved NO3−-N and total nitrogen TN removal efficiencies of 90.64 % and 80.94 %, respectively. This represents an increase of 24.15 % in the efficiency of TN removal compared with that of the nZVI system. The activity of the nZVI system diminished gradually after just three cycles, whereas nZVI@SiO2 maintained NO3−-N and TN removal efficiencies of 89.33 % and 78.08 %, respectively, after four cycles, respectively, indicating its sustainable ability to enhance aerobic denitrification. Cyclic voltammetry and electrochemical impedance spectroscopy demonstrated enhanced electron transfer efficiency of nZVI@SiO2. Furthermore, nZVI@SiO2 significantly promoted the activity of the electron transfer system, ATP levels, nitrate/nitrite reductase activity, contents of complexes I and III, and extracellular polymeric substances. nZVI@SiO2 significantly enhanced electron generation, transfer, and consumption during biological denitrification by functioning as both an electron donor and mediator. The findings implicate nZVI@SiO2 as a means to enhance nitrogen removal by aerobic denitrifying microorganisms in oligotrophic water via sustained donation of electrons.

Portocaval shunts' role in gut microbiota and hepatic encephalopathy: The gut-to-brain pathway

I read the study by Zhao et al with great interest. Although the study design was quite complicated, it was successful in raising awareness of science and relevant researchers. Thirty patients with liver cirrhosis and portal hypertension secondary to chronic hepatitis B were included in the study. They were treated for variceal bleeding and underwent trans-jugular intrahepatic portosystemic shunt to prevent the recurrence of variceal bleeding and to reduce portal pressure. The authors evaluated the effects of changes in gut microbiota (GM) on hepatic encephalopathy secondary to portocaval bypass. The GM is greatly affected by local and general factors, including herbal and medical drugs, a person's dietary characteristics (carnivorous, vegan, vegetarian), supplementary foods, drinking water sources, and living in a city center or town. Therefore, I congratulate Zhao et al for their concise and comprehensive study on a multifactorial subject.

A Comprehensive Review of Advanced Treatment Technologies for the Enhanced Reuse of Produced Water

Produced water (PW) is considered to be the largest source of industrial wastewater associated with oil and gas extraction operations for industrial production. It is a mixture of organic and inorganic compounds that has high complexity in terms of various characteristics. Globally, the volume of PW is increasing along with the expansion of gas and oil fields, leading to major impacts on the environment. Existing treatment technologies involve partially treating the PW through removing the suspended solids, heavy metals, without removing organic components and re-injecting the water underground using water disposal injection wells. The treatment process consists of a primary treatment unit to remove the particles, followed a secondary biological or chemical processing treatment, while the final treatment stage involves the use of a tertiary treatment unit to improve the water quality and remove the remainder of the undesired components. Moreover, while PW is considered one of the available options to be utilized as a water source, no alternate advanced treatment options on a commercial scale are available at present due to the limitations of existing PW treatment technologies, associated with their maintainability, sustainability, cost, and level of quality improvement. As such, research focused on finding an optimal treatment approach to improve the overall process continues to be conducted, with the aim of reusing the water instead of injecting it underground. This literature review discusses the latest advanced technologies for PW treatment aimed at reusing the full stream capacity of PW and eliminating the need for wastewater disposal via injection. It is concluded that researchers should focus on hybrid treatment technologies in order to remove the pollutants from PW, effectively allowing for its reuse.

An Analysis of Marketing Status of BT Cotton Seed in Devbhumi Dwarka District, Gujarat, India

The main objectives of the study were to assess the company’s distribution pattern of quality seed material their market share, marketing channels. Multistage sampling technique were adopted. The total 120 farmers and 20 dealers were selected from four taluka i.e., Bhanvad, Khambhalia, Kalyanpur, Okhamandal (Dwarka) of Devbhumi Dwarka district of Gujarat state. The five wholesaler/distributors were selected from district headquarters. The primary data were collected through personal interview with farmers, dealers, wholesaler/distributors using well-structured questionnaires and interview scheduled. Results revealed that most of Bt cotton growers to be middle aged farmers. The pattern of land holding distribution shows that majority of the Bt cotton growers belonged to the small and marginal land holding category. Social participation of Bt cotton growers shows that they are not members of any organization. The well was found to be the main source of irrigation water and most of Bt cotton growers were reported to attained primary level of education From the study, it was found that Rasi seed (P) Ltd. Occupied major market share in Devbhumi Dwarka district. Among different marketing channels, it was observed that marketing channel-I (MC-I) (Company→ Wholesaler/Distributors→ Dealer→ Bt cotton grower) is the most prevalent channel in the sampling area.

Influence of saline water sources on the crystallographic and morphological criteria of organic-template-free eco-synthesized zeolites

Influence of saline water sources on the crystallographic and morphological criteria of organic-template-free eco-synthesized zeolites

Indicadores de Sustentabilidade para Gestão da Água

Water safety involves the sustainable use and protection of water sources, so that water is available in adequate quantity and quality to health, livelihoods, ecosystems and production, in addition to protecting it from the negative effects of extreme weather events. Internationally, the concept of water security began being discussed in the 1990s, and more so since 2009, when the issue became the subject of a greater number of publications. In Brazil Federal Law 9433/97, which establishes the National Water Resources Policy, and corresponding state laws implicitly provide the concept of water security. However, the National Water Safety Plan was only launched in 2019, and has became the fundamental instrument for decision-making on this issue. The objective of the research was to pre-select indicators to analyze the water safety of the municipalities contemplated in the Capibaribe river watershed, within the framework of sustainable water management. To achieve the objective, the following methodology was adopted: pre-selection of indicators; application of a questionnaire to a panel of experts; structure a database. Thus, this work aims to bring subsidies that contribute to water security actions and public policies through the development of an indicator database. Additionally, this research is a proposal for future work, helping to define an equation of the water security index for the municipalities in the watershed.

Determinant Factors of Microbial Drinking Water Quality at the Point of Use in Rural Ethiopia: A Case Study of the South Gondar Zone

Access to safe drinking water is a fundamental human need for health and well-being implemented globally by the United Nations under Sustainable Development Goal (SDG) 6. Storing drinking water is common in rural areas of Ethiopia due to off-premises water sources and intermittent piped water supply. However, this practice can lead to further contamination during collection, transport, and storage, posing a risk to public health. The objective of this study was to identify the determinant factors of drinking water quality at the point of use in the rural setting of northwestern Ethiopia, South Gondar zone. A questionnaire survey was conducted, and water samples from 720 households were collected during the wet and dry seasons. The determinant factors were identified using the multivariable logistic regression model. About 39.2% of the surveyed households had basic water supply services, 41.9% were using unimproved sources, and 8.3% were using surface water. Only 9.4% were using basic sanitation services, and 57.2% were practicing open defecation. Safe water storage was practiced by 84.3% of households, while only 2% engaged in household water treatment. About 14% of dry and 8% of wet season samples from the storage were free from fecal coliform bacteria. Furthermore, 52.9% of dry and 62.2% of wet season samples fell under the high microbial health risk category. The season of the year, the water source type, storage washing methods, and the socioeconomic status of the household were identified as key predictors of household drinking water fecal contamination using the multivariable logistic regression model. It was observed that the drinking water in households had a high load of fecal contamination, posing health risks to consumers. To tackle these problems, our study recommends that stakeholders should enhance access to improved water sources, implement source-level water treatment, increase access to improved sanitation facilities, advocate for safe household water management practices, and endorse household water treatment methods.

Extreme Precipitation Events During the Wet Season of the South America Monsoon: A Historical Analysis over Three Major Brazilian Watersheds

Most of South America, particularly the region between the southern Amazon and southeastern Brazil, as well as a large part of the La Plata Basin, has its climate regulated by the South American Monsoon System. Extreme weather and climate events in these areas have significant socioeconomic impacts. The Madeira, São Francisco, and Paraná river basins, three major watersheds in Brazil, are especially vulnerable to wet and drought periods due to their importance as freshwater ecosystems and sources of water for consumption, energy generation, and agriculture. The scarcity of surface meteorological stations in these basins makes meteorological studies challenging, often using reanalysis and satellite data. This study aims to identify extreme weather (wet) and climate (wet and drought) events during the extended wet season (October to March) from 1980 to 2022 and evaluate the performance of two gridded datasets (CPC and ERA5) to determine which best captures the observed patterns in the Madeira, São Francisco, and Paraná river basins. Wet weather events were identified using the 95th percentile, and wet and drought periods were identified using the Standardized Precipitation Index (SPI) on a 6-month scale. In general, CPC data showed slightly superior performance compared to ERA5 in reproducing statistical measures. For extreme day precipitation, both datasets captured the time series pattern, but CPC better reproduced extreme values and trends. The results also indicate a decrease in wet periods and an increase in drought events. Both datasets performed well, showing they can be used in the absence of station data.