Drinking Water Samples Research Articles

A Dynamic Multiple Reaction Monitoring Analytical Method for the Determination of Fungicide Residues in Drinking Water

The extensive use of fungicides causes their continuous release into the environment through spraying, soil seepage, leaching, and runoff. It has been observed that their residues can be found in foods and a variety of environmental compartments, such as wastewater, lakes, rivers, sediments, drinking water sources (groundwater and surface water), treated water, and drinking water. A sensitive GC-MS/MS, using dynamic multiple reaction monitoring, an analytical method was developed to determine 10 fungicides (azoxystrobin, boscalid, captan, cyproconazole, cyprodinil, hexaconazole, metalaxyl, myclobutanil, paclobutrazol, and prochloraz) in drinking water. A solid-phase extraction method for sample preparations and validations was performed according to SANTE 2019 guidelines. All fungicides demonstrated mild or medium matrix effects (ME) ranging from 40.1% to 11.2%. Their recoveries ranged between 60% and 110%. The limits of detection were equal to or higher than 0.01 μg/L. The method was employed on 18 drinking water samples collected from public taps in Northern Evros, Greece, distributed in six sampling sites. Azoxystrobin, boscalid, cyproconazole, cypronidil, metalaxyl, and paclobutrazol mean concentrations did not surpass the allowable limit of 0.1 μg/L set by EU in any sampling site. Hexaconazole mean concentrations were higher than 0.1 μg/L in one sampling site, while prochloraz mean concentration showed limit exceedances in all sampling sites. Captan was not detected in any sampling site, and myclobutanil mean concentrations demonstrated exceedances of the permissible limit in four sampling sites. The presence of fungicide residues in the studied area is mainly due to the occasional point-sources pollution and preferential flow. Additionally, through the use of water, the risk of pesticides to human health was assessed for two different age groups. The sum of the hazard quotient values in each of the studied drinking water was less than unity. Consequently, the acute risk assessment procedure regards the examined drinking water as safe. Nevertheless, as prochloraz carcinogenic risk values were higher than the safe limit suggested by USEPA for both age groups, the existence of prochloraz residues raises concerns about chronic toxicity.

Prevalence of Skeletal Fluorosis in Northern Tanzania: A Follow-Up Study.

Skeletal fluorosis is a metabolic bone disease caused by excessive exposure to fluoride, predominantly through contamination of drinking water. This study aimed to identify all cases of skeletal fluorosis in Tindigani village situated in Northern Tanzania. This was done following changes in drinking water sources after a previous prevalence study in 2009 in this population. In a door-to-door cross-sectional study of Tindigani village, a sample of residents was assessed for skeletal fluorosis and dental fluorosis. Diagnosis of skeletal fluorosis was based on pre-defined angles of deformity of the lower limbs. Dental fluorosis was diagnosed and graded using the Thylstrup and Fejerskov Index. Samples from current drinking water sources underwent fluoride analysis. Tindigani village had a population of 1,944 individuals. Of the 1,532 individuals who were screened, 45 had skeletal fluorosis, giving a prevalence of 3.3% (95% CI=2.4, 4.3). Dental fluorosis was present in 82.5% of those examined (95% CI=79.8, 85.3). Dental fluorosis was present in all individuals with skeletal fluorosis and at higher grades than in the rest of the population. Drinking water samples were collected from 28 sources. These included piped, surface, well, and borehole water sources. Fluoride concentrations ranged from 0.45-38.59 mg/L of fluoride. Skeletal fluorosis is an ongoing but preventable health problem in the current population. The delivery of sustainable low fluoride piped water to this community would be of clear health benefit. This has been addressed at a local level.

Estimation of radioactivity in soil and drinking water samples from Northern Gulbarga District of Karnataka.

The gamma activity of the radionuclides238U, 232Th and 40K were measured in surface soil samples collected from 40 villages of Aland, Afzalpur, Ganaghapur and Kamalapur talukas of Northern Gulbarga district, Karnataka. The gamma activity of natural radionuclides were measured using 4" × 4" NaI (Tl) scintillation detector, the spectrum was analysed using a PC based 1k MCA (winTMCA 32 scinti SPEC) and the 222Rn activity concentrations in drinking water were determined by the Emanometry method. The activity of 238U, 232Th and 40K was found to be in the range from 14.3±0.3 to 64.5±6.1, 15.4±0.2 to 95.0±4.1 and 21±06 to 323±09 Bqkg-1, respectively. Outdoor AED from 0.023 to 0.07 mSvy-1 and all the radiological hazards indices were well within the safe limit. The 222Rn activity in ground water is found to vary from 1.11 to 66.6 Bql-1. The total annual effective doses due to 222Rn inhalation and ingestion range from 3.02 to 181.81μSvy-1, respectively, with an average value of 77.18μSvy-1.

Consumption of chewing tobacco alters the serum metal contents in pregnant women at Tandojam and adjoining areas.

Chewing tobacco may play a contributing role in complications during pregnancy as it contains various kinds of toxic metals such as lead (Pb), cadmium (Cd), cobalt (Co), manganese (Mn), chromium (Cr), and can cause alteration in serum metal concentration. Hence, the present study aimed to explore the effects of chewing tobacco consumption on serum metal contents in pregnant women. A total number of 200 chewing tobacco consumer pregnant women and 200 age-matched non-consumer pregnant women were selected for the study from the outpatient department of gynaecology at Rural Health Centre Tandojam, Pakistan. After obtaining the sociodemographic characteristics of all participants, 10ml of venous blood was also drawn for serum metal analysis by atomic absorption spectroscopy. Different chewing tobacco samples consumed by consumer pregnant women were collected from local shops of Tandojam, Pakistan. Drinking water samples from the residential areas of consumer and non-consumer pregnant women were prepared and analysed for the same metal contents. In present study, serum Pb, Cd, K and Co were found significantly increased in CPW as compared to NCPW. Serum Pb was found significantly increased in gutkha consumers in comparison to mainpuri consumers. Serum Pb, Cd, and Co were present with significantly increased concentration in serum of CPW who were taking canal and well water for drinking purpose when compared with NCPW. Significant negative strong correlation of serum Pb with K and Cr of drinking water and Na of chewing tobacco samples were observed. Strong positive correlation of serum Cd and Cr with Co of drinking water had been observed. Whereas, serum maternal Co was strongly negatively correlated with Mn of chewing tobacco samples, and serum Cu of CPW had a strong positive correlation with K and Cr of drinking water and Na of chewing tobacco samples.In conclusion, consumption of chewing tobacco alters the serum metal contents in pregnant women at Tandojam and adjoining areas, Pakistan.

Detection of H. pylori outer membrane protein (HopQ) biomarker using electrochemical impedimetric immunosensor with polypyrrole nanotubes and carbon nanotubes nanocomposite on screen-printed carbon electrode

Helicobacter pylori (H. pylori) is classified as a class I carcinogen that colonizes the human gastrointestinal (GI) tract. The detection at low concentrations is crucial in combatting H. pylori. HopQ protein is located on H. pylori's outer membrane and is expressed at an early stage of contamination, which signifies it as an ideal biomarker. In this study, we presented the development of an electrochemical impedimetric immunosensor for the ultra-sensitive detection of HopQ at low concentrations. The sensor employed polypyrrole nanotubes (PPy-NTs) and carboxylated multi-walled carbon nanotubes (MWCNT-COOH) nanocomposite. PPy-NTs were chosen for their excellent conductivity, biocompatibility, and redox capabilities, simplifying sample preparation by eliminating the need to add redox probes upon measurement. MWCNT-COOH provided covalent binding sites for HopQ antibodies (HopQ-Ab) on the biosensor surface. Characterization of the biosensor was performed using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), contact angle measurements, and electrochemical impedance spectroscopy (EIS), complemented by numerical semiempirical quantum calculations. The results demonstrated a dynamic linear range of 5 pg/mL to 1.063 ng/mL and an excellent selectivity, with the possibility of excluding interference using EIS data, specifically charge transfer resistance and double-layer capacitance as multivariants for the calibration curve. Using two EIS components, the limit of detection is calculated to be 2.06 pg/mL. The biosensor was tested with a spiked drinking water sample and showed a signal recovery of 105.5% when detecting 300 pg/mL of HopQ. This novel H. pylori biosensor offers reliable, simple, portable, and rapid screening of the bacteria.

Molecular detection of waterborne pathogens in infants' drinking water and their relationship with water quality determinants in eastern Ethiopia: loop-mediated isothermal amplification (LAMP)-based study.

Cryptosporidium, Shigella, toxin-producing Escherichia coli, and rotavirus were reported to be the most responsible for severe and fatal diarrhea among infants. This study aimed to investigate the presence of these pathogens in infants' drinking water samples and analyzing using water quality determinants in eastern Ethiopia. A molecular (LAMP)-based cross-sectional study design was employed. A total of 410 and 37 water samples were tested from infant point-of-use at household and corresponding water source, respectively, from June 2020 to May, 2021. Cryptosporidium, Shigella, toxin-producing E. coli, and rotavirus were detected in 28.5, 30.0, 26.3, and 32.2%, of water samples tested from infant point-of-use, respectively. About 13.2% of the water samples were positive for all (four) pathogens together. Cryptosporidium, Shigella, toxin-producing E. coli, and rotavirus were detected in 27.0, 32.4, 29.7, and 37.8%, of water samples tested from water sources, respectively. Positive significant correlation was observed between infant point-of-consumption and water sources from which it is drawn toward the presence of each targeted pathogen. Unimproved water source showed a strong significant association with the presence of Cryptosporidium, Shigella and toxin-producing E. coli. Therefore, efforts should be made in development of improved water sources, source protection safety and health education to caretakers of infants.

Detection of emerging disinfection by-products by reversed-phase ion-pair chromatography electrospray-ionization mass spectrometry in drinking water

A sensitive and specific methodology that allows unequivocal identification of polydiallyldimethylammonium chloride (PDADMAC) disinfection by-product it monomer diallyldimethylammonium chloride (DADMAC) in drinking water samples based on reversed-phase ion-pair chromatography–electrospray ionization – mass spectrometry was optimized. Ion-pair reagent heptafluorobutyric (HFBA) was found to play a crucial role in the optimization of chromatographic parameters. The chromatographic retention time was optimized by varying concentrations of ion-pair reagent, flow rate, and column temperature to enable good chromatographic retention and sensitivity of disinfection by-product of interest DADMAC in positive electrospray ionization and using selected ion monitoring (SIM) mode. The method was validated and showed good linear regression of 0.99 and a detection limit of 0.008 mg L−1. The developed method was applied in a drinking water treatment plant operated by Mgeni Water in Durban, South Africa, to detect trace levels of the disinfection by-product of interest (DADMAC) at various points of the treatment process. The concentration of DADMAC in the water treatment plant ranged from not detected up to 0.65 mg L−1. In addition, this work through mass spectrometry provides the first evidence of ion-pairing (465 m/z peak) between DADMAC and the reagent, which is a confirmation of online derivatization. Also, the use of ion-pair prevented dimerization of DADMAC (286 m/z peak) inside the ionization chamber leading to high sensitivity.

Drinking Water Contaminant Concentrations and Birth Outcomes.

Previous research in the US has found negative health effects of contamination when it triggers regulatory violations. An important question is whether levels of contamination that do not trigger a health-based violation impact health. We study the impact of drinking water contamination in community water systems on birth outcomes using drinking water sampling results data in Pennsylvania. We focus on the effects of water contamination for births not exposed to regulatory violations. Our most rigorous specification employs mother fixed effects and finds changing from the 10th to the 90th percentile of water contamination (among births not exposed to regulatory violations) increases low birth weight by 12% and preterm birth by 17%.

Fluoride exposure and pediatric kidney health in dry, wet and intermediate climatic zone communities in Sri Lanka: Implications from urinary Cystatin-C, and albumin-creatinine ratio

BackgroundHigh fluoride exposure is increasingly discussed attributing to kidney injury as a causative factor. Depending on geochemistry, differential fluoride levels in drinking water are identified in different regions in Sri Lanka. However, the levels of fluoride exposure, and associations with kidney health has not been adequately studied in Sri Lanka, particularly in pediatric communities. Hence, the present study aimed to assess fluoride exposure in selected pediatric communities in the dry, wet and intermediate climatic zones in Sri Lanka, along with an assessment of renal health using urinary Cystatin-C (uCys-C), and albumin-creatinine ratio (uACR). MethodsWe conducted a cross-sectional study with school students in selected education zones representing dry (N = 331), wet (N = 152), and intermediate (N = 292) climatic zones in Sri Lanka. Fluoride contents in urine and drinking water were assessed as measures of fluoride exposure. ResultsThe median (interquartile distance) urinary fluoride levels of participants in the dry, wet and intermediate zones were 1.63(1.04–2.85), 1.29(0.85–2.21), and 1.07(0.61–1.98) mg/gCr while the fluoride contents of drinking water samples were 1.76(1.36–2.30), 0.25(0.18–0.37), and 0.43(0.26–0.63) ppm respectively with significant differences among the three groups. Median uCys-C level (ng/mgCr) of the participants in intermediate zone [30.26(8.49–71.44)] was significantly low (p < 0.05) compared to that of the participants in dry zone [56.19(7.08–211.8)], and wet zone [66.29(30.43–125.20)]. The incidences of elevated uCys-C levels above reference intervals in participants of dry zone (47.7%), and wet zone (50.0%) were significantly high (p < 0.001) compared to the intermediate zone (26.4%). ConclusionRelatively high fluoride exposure is likely in dry and wet zone communities compared to the intermediate zone along with significantly higher incidence of uCys-C levels above reference intervals in study groups with higher fluoride exposure. However, to conclude a clear link between fluoride exposure and kidney health we need in-depth studies.

Appraisal of treated drinking water quality from arsenic removal units in West Bengal, India: Approach on safety, efficiency, sustainability, future health risk and socioeconomics

The present study depicts the true failed scenario of the arsenic (As) removal units (ARU) in West Bengal by evaluating their treated water quality. Annual As removal efficiency of the 12 studied ARUs range between 35.2% and 82.6%. A comprehensive physico-chemical parameters and trace elements analysis find almost 25% and 16.7% of treated drinking water samples with poor water quality index (WQI) and high heavy metal evaluation index (HEI), respectively. The pond-based water treatment plant maintains the production of continuous As-safe water with a range between 60.2% and 66.7% due to its high Fe/As ratio. It’s a discontent concluding the treated drinking water of the groundwater based-ARUs were observed with sufficient As mediated cancer risk (3 ×10−3). The non-cancer risk (HQ) of As is safe for the surface water treatment plant (0.38), whereas it is threatening for the groundwater based-ARUs (7.44). However, the drinking water samples are safe in view of HQ from the other trace elements like Hg, Al, Cd, Cr, Pb, F- and NO3-. Small scale ARU could be a feasible mitigation strategy in reducing the As menace in the long run if the plants are maintained correctly. Nevertheless, surface treated water is the most sustainable solution as withdrawal of groundwater for drinking purpose is not a viable practice.

Preservation and Handling Practices of Household Drinking Water in Ahmedabad city with special reference to Bacterial Contamination and Diarrheal Episode in Children: A Cross Sectional Study

Background: Safe drinking water is essential for healthy human life. Presence of coliform organism, E. coli in particular, has been found to be the most specific bacteriological indicator of faecal contamination. Studying their preservation and handling practices of household drinking water, its contamination and diarrheal episodes in children is very necessary for hygiene promotion intervention. Methods: This cross-sectional study was conducted at urban field practice area of community medicine department B.J.M.C, Ahmedabad in year 2020-2021. Total 168 Drinking water samples were collected from each household and tested at microbiology department. Information regarding household characteristics, preservation and handling practices of drinking water were gathered from mother using pre-tested and pre-designed proforma. Data were entered in Microsoft excel and analysed using Epi-info Software. Result: Out of 168 households studied, 165(98.2%) households used matka / earthen pot and 161(95.8%) used narrow necked covered container to preserve drinking water. Only in 10 (5.8%) households’ water was filtered with folded cotton cloth at the time of collection. 101 (60%) water containers did have tap while 67 (39.8%) didn’t have it. 4/168 (2.3%) samples were bacteriologically not acceptable for drinking purpose. Conclusion: Narrow necked coveredmatka (earthen pot) was the most commonly used container to preserve drinking water. Though prevalence of bacterial contamination and ADD episodes in under five child were low due to pre-treated piped water supply, diarrhoeal morbidity is more in household where broad necked, non tapped containers used. Education of mother has positive impact on preservation and handling practices of drinking water. Keywords: Preservation, Handling, Drinking water, Coliform, Diarrheal episode, Under 5 children

A Comparative Assessment of the Physicochemical and Microbiological Qualities of Some Drinking Water Sources in Diobu, Portharcourt, Nigeria

Diseases caused as a results of drinking contaminated water pose a severe risk to the public's health. In the current study, various drinking water sources in Diobu, Port Harcourt, were evaluated and their microbiological and physicochemical characteristics were compared. Drinking water samples were collected from a borehole and a sachet (packaged) source. Physicochemical and bacteriological investigations were conducted using standard analytical techniques. The results of physiochemical parameters revealed that sachet water samples had higher pH values than borehole water. The borehole water samples had a mean pH of 4.37±1.21 which was much lower than the W.H.O.- recommended range (6.5-8.5). The study’s Total Suspended Solids readings were within the permissible limits of 30.0 mg/l. The borehole samples had the highest concentration of 6.5±4.31mg/l, while the sachet water samples had the lowest concentration of 2.5±1.5 mg/l. Total Dissolved Solids ranged between 15.8±13.5mg/l in sachet water and 55.6±33.4 mg/l in samples from boreholes. The Electrical Conductivity values were recorded as 33.5±28.4 µScm-1 in sachet water and 136.6±73.9 µScm-1 in borehole water. The mean total alkalinity value in sachet water was 0.57±0.29 mg/l whereas in borehole water, it was 3.29±1.39 mg/l. For sachet water and borehole water, the levels of water hardness ranged from 1.95±0.84 mg/l to 10.67±3.21 mg/l, respectively. The range of biological oxygen demand was &lt; 1±0.00 (for sachet water) to 2.13±13 (for borehole water). Dissolved oxygen levels ranged from 1.72±0.70 mg/l in sachet water to 1.95±0.62 mg/l in borehole water. Chemical oxygen demand levels ranged from 2.38±1.18mg/l (Sachet water) to 11.31±9.49 (Borehole water) while Turbidity ranged from &lt;1±0.00 NTU (Sachet water) to 1.1±0.64 NTU (Borehole water). Except for Chemical Oxygen Demand, there was no difference in the values that were observed that was significant at P≥ 0.05 in this study. The mean total bacterial counts ranged from 2.0 x 104 CFU/ml in sachet water to 9.0 x104 CFU/ml in borehole water, demonstrating high levels of contamination in the borehole water from human contamination. Comparatively to the other water sources, sachet water had the lowest overall bacterial and coliform levels. However, because the bacteriological values for total coliform counts was above the WHO threshold of zero per 100 ml, they did not comply with international standards. Salmonella spp., Pseudomonas spp., Staphylococcus spp., and Escherichia coli were the pathogenic bacteria of public health significance that were isolated from the diverse water samples. Five distinct isolates of fungi, including Penicillium spp., Aspergillus niger, Aspergillus flavus, Trichoderma spp., and Mucor spp., were found. In comparison to borehole water, which had the most bacterial pollutants, sachet water tests had the fewest. It is advised that the water sources be treated before being used for any domestic purposes as the water sources in this research area are not suitable for human consumption.

Phenotypic and genotypic characterization of colistin-resistant Escherichia Coli with mcr-4, mcr-5, mcr-6, and mcr-9 genes from broiler chicken and farm environment

BackgroundColistin is an antibiotic used as a last-resort to treat multidrug-resistant Gram-negative bacterial infections. Colistin had been used for a long time in veterinary medicine for disease control and as a growth promoter in food-producing animals. This excessive use of colistin in food animals causes an increase in colistin resistance. This study aimed to determine molecular characteristics of colistin-resistant Escherichia coli in broiler chicken and chicken farm environments.ResultsFour hundred fifty-three cloacal and farm environment samples were collected from six different commercial chicken farms in Kelantan, Malaysia. E. coli was isolated using standard bacteriological methods, and the isolates were tested for antimicrobial susceptibility using disc diffusion and colistin minimum inhibitory concentration (MIC) by broth microdilution. Multiplex PCR was used to detect mcr genes, and DNA sequencing was used to confirm the resistance genes. Virulence gene detection, phylogroup, and multilocus sequence typing (MLST) were done to further characterize the E. coli isolates. Out of the 425 (94%; 425/453) E. coli isolated from the chicken and farm environment samples, 10.8% (48/425) isolates were carrying one or more colistin-resistance encoding genes. Of the 48 colistin-resistant isolates, 54.2% (26/48) of the mcr positive isolates were genotypically and phenotypically resistant to colistin with MIC of colistin ≥ 4 μg/ml. The most prominent mcr gene detected was mcr-1 (47.9%; 23/48), followed by mcr-8 (18.8%; 9/48), mcr-7 (14.5%; 7/48), mcr-6 (12.5%; 6/48), mcr-4 (2.1%; 1/48), mcr-5 (2.1%; 1/48), and mcr-9 (2.1%; 1/48) genes. One E. coli isolate originating from the fecal sample was found to harbor both mcr-4 and mcr-6 genes and another isolate from the drinking water sample was carrying mcr-1 and mcr-8 genes. The majority of the mcr positive isolates were categorized under phylogroup A followed by phylogroup B1. The most prevalent sequence typing (ST) was ST1771 (n = 4) followed by ST206 (n = 3). 100% of the mcr positive E. coli isolates were multidrug resistant. The most frequently detected virulence genes among mcr positive E. coli isolates were ast (38%; 18/48) followed by iss (23%; 11/48). This is the first research to report the prevalence of mcr-4, mcr-5, mcr-6, mcr-7, and mcr-8 genes in E. coli from broiler chickens and farm environments in Malaysia.ConclusionOur findings suggest that broiler chickens and broiler farm environments could be reservoirs of colistin-resistant E. coli, posing a risk to public health and food safety.

Construction of optical dual-mode sensing platform based on green emissive carbon quantum dots for effective detection of ClO- and cellular imaging

Hypochlorite (ClO-) is an important redox regulator in reactive oxygen species, which play a considerable role in oxidative stress and related diseases. Hence, accurate and sensitive monitoring of ClO- concentration was urgently needed in the fields of life sciences, food and environment. Bright green fluorescent carbon quantum dots (G-CQDs) were synthesized utilizing one-step hydrothermal method with citric acid and acriflavine precursors. Through TEM, FTIR, XPS and zeta potential characterization procedures, G-CQDs illustrated uniformly dispersed and significant number of –NH2 and –OH on the surface. Meanwhile, the fluorescence and colorimetric analysis exhibited wide linear range and low detection limit response to ClO-. The fluorescence changes of G-CQDs were identified via smartphone to realize mobile sensing of ClO-. Subsequently, G-CQDs was applied for visualization and quantitative detection of ClO- in drinking water samples with satisfactory recovery rate. More importantly, G-CQDs demonstrated good water solubility, optical stability and excellent biocompatibility, which offered a promising analysis approach in cell imaging and exogenous ClO- detection in living cells. G-CQDs illustrated bright prospect and great potential in practical application of ClO- associated disease prevention and early clinical diagnosis.

On-site monitoring of Escherichia coli O157:H7 in drinking water based on rapid detection of the rfbE gene at the single copy level

The sensitive and on-site detection of highly pathogenic Escherichia coli O157:H7 (E. coli O157:H7) is of great importance to ensure public health. However, conventional methods for E. coli O157:H7 detection may suffer disadvantages such as high expense and time consumption. Herein, we reported a cost-effective colorimetric platform based on loop-mediated isothermal amplification (LAMP) for ultrasensitive and rapid detection of E. coli O157:H7. In this study, a novel quantitative colorimetric LAMP assay was established by in-situ measurement of hydroxy naphthol blue (HNB) color change with a designed portable device, which was applied to the amplification of the specific rfbE gene of E. coli O157:H7. As expected, this method featured a wide linear range (100-104 copies µL−1) with excellent linear regression analysis (R2 > 0.99) and possessed a record-low detection limit of 1 copy µL−1 to lower the risk of missed detection. The proposed strategy could be employed on drinking water samples with favorable recoveries and also demonstrated potential in the analysis of complex samples. This work exhibits the promising application prospect in on-site detection without the need for expensive instrumentation and seeks to provide an original paradigm for the rapid and sensitive detection of waterborne pathogens.

Microbial community of municipal drinking water in Hangzhou using metagenomic sequencing

While traditional culture-dependent methods can effectively detect certain microorganisms, the comprehensive composition of the municipal drinking water (DW) microbiome, including bacteria, archaea, and viruses, remains unknown. Metagenomic sequencing has opened the door to accurately determine and analyze the entire microbial community of DW, providing a comprehensive understanding of DW species diversity, especially in the context of public health concerns during the COVID-19 era. In this study, we found that most of the culturable bacteria and some fecal indicator bacteria, such as Escherichia coli and Pseudomonas aeruginosa, were non-culturable using culture-dependent methods in all samples. However, metagenomic analysis showed that the predominant bacterial species in the DW samples belonged to the phyla Proteobacteria and Planctomycetes. Notably, the genus Methylobacterium was the most abundant in all water samples, followed by Sphingomonas, Gemmata, and Azospirilum. While low levels of virulence-associated factors, such as the Esx-5 type VII secretion system (T7SS) and DevR/S, were detected, only the erythromycin resistance gene erm(X), an rRNA methyltransferase, was identified at low abundance in one sample. Hosts corresponding to virulence and resistance genes were identified in some samples, including Mycobacterium spp. Archaeal DNA (Euryarchaeota, Crenarchaeota) was found in trace amounts in some DW samples. Viruses such as rotavirus, coxsackievirus, human enterovirus, and SARS-CoV-2 were negative in all DW samples using colloidal gold and real-time reverse transcription polymerase chain reaction (RT‒PCR) methods. However, DNA encoding a new order of reverse-transcribing viruses (Ortervirales) and Herpesvirales was found in some DW samples. The metabolic pathways of the entire microbial community involve cell‒cell communication and signal secretion, contributing to cooperation between different microbial populations in the water. This study provides insight into the microbial community and metabolic process of DW in Hangzhou, China, utilizing both culture-dependent methods and metagenomic sequencing combined with bioinformatics tools during the COVID-19 pandemic era.

Tritium contents in drinking and surface seawaters before the nuclear power plant planned in Sinop (Türkiye) and their radiological risks on human population.

This study aims to determine the background levels of tritium radioisotope in drinking and seawater samples of Sinop province before the nuclear power plant was established in Sinop. In this context, a total of 174 water samples were collected, these are as follows: nine drinking water samples from the Sinop center and districts and 165 seawater samples from the seacoast from Samsun to Kastamonu. Tritium concentrations in the collected water samples were measured by the liquid scintillation counter. The minimum detectable activity for the method used was found to be 1.48 Bq/L. The tritium concentrations of the seawater and drinking water samples were found in the range of <MDA (minimum detectable activity)-6.29 Bq/L and 2.45-3.17 Bq/L, respectively. In addition, the annual effective dose rates of the people consuming these drinking waters due to the tritium radioisotope were calculated separately for infants, children and adults and found to be 12.12, 16.96 and 35.38 nSv, respectively.

Validation and measurement uncertainty of the determination of 24 elements in drinking water using ICP-MS

Abstract In this study, the concentrations of 24 elements, which are suspicious to be found in drinking and utility waters for the province of Antalya/Turkey, were determined using an inductively coupled plasma-mass spectrometer (ICP-MS). Validated methods with a low limit of detection are required to analyze such waters. The method was validated considering selectivity, limits of detection and quantification, sensitivity, linearity, operating range, accuracy, precision, and measurement uncertainty. All monitored isotope calibration plots had a correlation coefficient of 0.9994 or higher. According to the results of recovery, the expected results of all element isotopes were determined in the range of 94–104%. The average precision quantities for items were calculated as percent relative standard deviation (%RSD) between 0.10 and 2.31%. The analytical method provided here for detecting the concentrations of 24 elements in drinking water samples with demonstrated traceability and estimated uncertainty can yield reliable and internationally comparable results.

Ag-containing metal organic framework reacted with AsH3: Mechanism and application for inorganic arsenic detection by hydride generation-smartphone RGB readout colorimetric system.

The reaction mechanism of Ag-containing metal organic framework (Ag-BTC) and hydrogen arsenide (AsH3) was discussed in detail in this work. Silver ions in Ag-BTC were reacted with AsH3, and silver nanoparticles were generated on the surface of Ag-BTC, causing its color changed. This property was further applied to a hydride generation-colorimetric analytical system. As(III) was converted to AsH3via hydride generation and then reacted with the Ag-BTC (immobilized on test paper), leading to the test paper changed from white to black. Visual colorimetric and smartphone RGB readout mode were used for this analytical system. The results could be readout by naked-eye in visual colorimetric mode and a smartphone in RGB readout mode. Under the optimized conditions, As(III) concentration as low as 10μg/L and 50μg/L could be readout by smartphone and naked-eye, respectively. This method was further successful applied to As(III) determination in real samples (drinking water samples and scented tea samples), with recoveries of 91-113%.

Risk assessment due to ingestion of uranium and radon in the drinking water samples of the Budhakedar region in Garhwal Himalaya, India

Risk assessment due to ingestion of uranium and radon in the drinking water samples of the Budhakedar region in Garhwal Himalaya, India