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1.
Chemosphere ; 282: 131048, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34470147

RESUMO

Antimicrobial resistance (AMR), as well as the development of biofilms in drinking water distribution systems (DWDSs), have become an increasing concern for public health and management. As bulk water travels from source to tap, it may accumulate contaminants of emerging concern (CECs) such as antibiotics and heavy metals. When these CECs and other selective pressures, such as disinfection, pipe material, temperature, pH, and nutrient availability interact with planktonic cells and, consequently, DWDS biofilms, AMR is promoted. The purpose of this review is to highlight the mechanisms by which AMR develops and is disseminated within DWDS biofilms. First, this review will lay a foundation by describing how DWDS biofilms form, as well as their basic intrinsic and acquired resistance mechanisms. Next, the selective pressures that further induce AMR in DWDS biofilms will be elaborated. Then, the pressures by which antibiotic and heavy metal CECs accumulate in DWDS biofilms, their individual resistance mechanisms, and co-selection are described and discussed. Finally, the known human health risks and current management strategies to mitigate AMR in DWDSs will be presented. Overall, this review provides critical connections between several biotic and abiotic factors that influence and induce AMR in DWDS biofilms. Implications are made regarding the importance of monitoring and managing the development, promotion, and dissemination of AMR in DWDS biofilms.


Assuntos
Água Potável , Metais Pesados , Antibacterianos/toxicidade , Biofilmes , Farmacorresistência Bacteriana , Humanos , Metais Pesados/toxicidade
2.
Chemosphere ; 282: 131106, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34470160

RESUMO

An assessment of uranium contents and distribution in drinking water limescale has been conducted in the Republic of Bashkortostan (RB), Russia. A total of 515 limescale samples from 262 settlements of the RB were analyzed. The spread of U concentration values in limescale samples ranged from 0.01 to 61.0 µg/g. Elevated U concentrations in the West of the RB corresponded with the horsts of the granite-gneiss crystalline basement of the South-Tatar Dome and their Eastern slopes, the areas with the Lower Permian red beds and the oil and gas fields. The U migration from the granite-gneiss basement is attributed to the tectonic factor and hydrocarbons movement. Elevated concentrations of U within the South of the RB are associated primarily with the deposits of the Southern Ural brown coal basin. The Bashkir Trans-Urals anomalies are mainly associated with Lower Paleozoic eclogite complex, Devonian and Carboniferous volcanic-sedimentary, carbonate, intrusive formations, as well as the Jurassic cover of terrigenous marine sediments. The negative anomalies of the spatial distribution of U are located in the area of the Ufimian Plateau mainly composed of limestone.


Assuntos
Água Potável , Urânio , Poluentes Radioativos da Água , Geologia , Campos de Petróleo e Gás , Urânio/análise , Poluentes Radioativos da Água/análise
3.
J Appl Oral Sci ; 29: e20200939, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34495104

RESUMO

BACKGROUND: Arsenic contamination in the environment and groundwater is a major global public health problem. Several researchers suggest that the toxicity of arsenic could be related to oral cancer development, usually resulting from potentially malignant lesions. During pathological processes, salivary proteins suffer modifications, which could lead to the discovery of new biomarkers. OBJECTIVE: To analyze the protein profile in human saliva samples from a rural population exposed to high levels of arsenic in drinking water and its association with potentially malignant lesions. METHODOLOGY: This observational, analytic and cross-sectional design included 121 patients from the state of Graneros (Tucumán, Argentina). Arsenic concentration in drinking water was determined and, according to the values obtained, individuals were divided into 2 groups: exposed group and non-exposed group. Saliva samples were obtained, and total protein concentration was measured by Bradford method. Finally, Laemmli SDS-polyacrylamide gel electrophoresis was conducted to obtain the protein profile. RESULTS: Total protein concentration in saliva was lower in the exposed group than in the non-exposed group. Average areas of 20 and 42 KDa bands were significantly lower in exposed group than non-exposed group. CONCLUSION: Chronic intake of high arsenic concentrations in drinking water produces changes in the salivary protein profile, which is associated with the presence of potentially malignant lesions.


Assuntos
Arsênio , Água Potável , Poluentes Químicos da Água , Argentina , Arsênio/análise , Arsênio/toxicidade , Estudos Transversais , Água Potável/análise , Monitoramento Ambiental , Humanos , Projetos Piloto , População Rural , Proteínas e Peptídeos Salivares , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
4.
Water Res ; 203: 117543, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34433109

RESUMO

According to the European Directives (UE) 2020/2184 and 2009/54/EC, which establishes the sanitary criteria for water intended for human consumption in Europe, water suitable for human consumption must be free of the bacterial indicators Escherichia coli, Clostridium perfringens and Enterococcus spp. Drinking water is also monitored for heterotrophic bacteria, which are not a human health risk, but can serve as an index of bacteriological water quality. Therefore, a rapid, accurate, and cost-effective method for the identification of these colonies would improve our understanding of the culturable bacteria of drinking water and facilitate the task of water management by treatment facilities. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is potentially such a method, although most of the currently available mass spectral libraries have been developed in a clinical setting and have limited environmental applicability. In this work, a MALDI-TOF MS drinking water library (DWL) was defined and developed by targeting bacteria present in water intended for human consumption. This database, made up of 319 different bacterial strains, can contribute to the routine microbiological control of either treated drinking water or mineral bottled water carried out by water treatment and distribution operators, offering a faster identification rate compared to a clinical sample-based library. The DWL, made up of 96 bacterial genera, 44 of which are not represented in the MALDI-TOF MS bacterial Bruker Daltonics (BDAL) database, was found to significantly improve the identification of bacteria present in drinking water.


Assuntos
Água Potável , Purificação da Água , Bactérias , Bases de Dados Factuais , Humanos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
5.
Water Res ; 203: 117493, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34365194

RESUMO

Developing strategies to identify the origins of contaminants in watersheds is crucial for source water protection. The use of multiple tracers improves the ability to identify contamination events originating from various land use activities. The objective of this study was to evaluate the use of acesulfame and chloride as co-tracers to represent the impact of pollution originating from wastewater and road de-icing on water quality in a municipal drinking water source. The study included a two-year sampling and water quality analysis program in numerous locations within a drinking water reservoir comprising a lake (upstream) and a river (downstream) which supply raw water to a municipal water treatment plant. Results showed that the spatial variability of acesulfame and chloride within the watershed of the lake-river systems depends on the location of contaminant sources, mainly municipal wastewater and septic tank discharges (for acesulfame) and the presence of small tributaries of the lake and river (for chloride). Temporal variability of the tracers under study differed according to the sampling location and was mainly affected by seasonal conditions. Correlation analyses between the two tracers in lake and river waters (in terms of concentrations and loads) made it possible to pinpoint the probable origins of contamination. The assessment of the spatio-temporal variability of these co-tracers within the lake-river watersheds allowed for the delineation of priority intervention zones as a decision-making tool for municipal authorities in improving drinking water source protection.


Assuntos
Água Potável , Poluentes Químicos da Água , Cloretos , Monitoramento Ambiental , Tiazinas , Águas Residuárias , Poluentes Químicos da Água/análise
6.
Water Res ; 203: 117506, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34371231

RESUMO

The bacterial growth potential (BGP) of drinking water is widely assessed either by flow cytometric intact cell count (BGPICC) or adenosine triphosphate (BGPATP) based methods. Combining BGPICC and BGPATP measurements has been previously applied for various types of drinking water having high to low growth potential. However, this has not been applied for water with ultra-low nutrient content, such as remineralised RO permeate. To conduct a sound comparison, conventionally treated drinking water was included in this study, which was also used as an inoculum source. BGPICC, BGPATP, intact cell-yield (YICC), and ATP-yield (YATP) were determined for conventionally treated drinking water (Tap-water) and remineralised RO permeate (RO-water). In addition, both BGPICC and BGPATP methods were used to identify the growth-limiting nutrient in each water type. The results showed that the BGPICC ratio between Tap-water/RO-water was ∼7.5, whereas the BGPATP ratio was only ∼4.5. Moreover, the YICC ratio between Tap-water/RO-water was ∼2 (9.8 ± 0.6 × 106 vs. 4.6 ± 0.8 × 106 cells/µg-C), whereas the YATP ratio was ∼1 (0.39 ± 0.12 vs. 0.42 ± 0.06 ng ATP/µg-C), resulting in a consistently higher ATP per cell in RO-water than that of Tap-water. Both BGPICC and BGPATP methods revealed that carbon was the growth-limiting nutrient in the two types of water. However, with the addition of extra carbon, phosphate limitation was detected only with the BGPICC method, whereas BGPATP was not affected, suggesting that a combination of carbon and phosphate is essential for biomass synthesis, whereas carbon is probably utilised for cellular activities other than cell synthesis when phosphate is limited. It was estimated that the intact cell-yield growing on phosphate would be 0.70 ± 0.05 × 109 cells/µg PO4-P.


Assuntos
Água Potável , Purificação da Água , Trifosfato de Adenosina , Contagem de Células , Nutrientes , Osmose
7.
Water Res ; 203: 117485, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34371232

RESUMO

Hard water and elevated ammonia are problems for many United States groundwater drinking water utilities, and some utilities, particularly those in the Midwest, face both challenges. Ion (cation) exchange (IX) is a common treatment technique for hardness reduction (i.e., softening) and may be used to remove ammonia as well, but these constituents may compete in IX and impact overall treatment performance. Few data have been reported on the impact on ammonia concentrations when using IX for softening in full-scale systems. This study investigated four full-scale groundwater treatment plants in Illinois that practice IX for softening (raw water hardness > 220 mg/L as CaCO3) and have elevated groundwater ammonia concentrations (> 2 mg N/L). Sampling throughout the year revealed consistent finished water hardness levels but variable ammonia concentrations. Ammonia removal varied and depended on how much water had been treated since the last regeneration. High ammonia removal (sometimes > 90%) occurred in the first half of the IX service cycle, while effluent ammonia concentrations increased compared to the influent (sometimes > 200%) towards the end of the IX cycle (total length 50,000-92,000 gallons [190-350 m3]). Ammonia removal efficiency varied among the plants, but the overall trends were similar. Because variable ammonia concentrations may make it difficult to produce a consistent total chlorine residual, they can negatively impact disinfection and water quality in the distribution system. Ammonia concentrations should be considered when designing softening systems to determine regeneration frequency, develop blending strategies, or include an alternative ammonia treatment process before IX softening to produce a more stable and consistent finished water.


Assuntos
Água Potável , Poluentes Químicos da Água , Purificação da Água , Amônia , Troca Iônica , Qualidade da Água , Abrandamento da Água
8.
Sci Total Environ ; 791: 148389, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34412389

RESUMO

The present study was conducted to comprehensively evaluate watershed sustainability with the help of an initiative barometer developed based on different dimensions of social, economic, environmental, and policy. The newly developed barometer was then applied to assess the temporal variation of sustainability for the Shazand Watershed, Iran, for four-node years of 1986, 1998, 2008, and 2016. The appropriate criteria were then adapted to calculate the study dimensions. The effect sizes of selected criteria on each dimension were also determined. Consequently, the status of each dimension and integrated watershed sustainability status were mapped for four-node years. The results indicated that study dimensions were unevenly distributed over the Shazand Watershed. So that, the social dimension had high effectiveness across different sub-watersheds, and the policy dimension had a poor situation in all study years. In addition, the respective sustainability index of 0.32, 0.32, 0.35, and 0.35 for node years of 1986, 1998, 2008, and 2016 verified a slight improvement. Overall, the proposed barometer of sustainability facilitated understanding the dimensional sustainability and comprehensive watershed sustainability and provided references for policy formulations and watershed management. Besides, the developed barometer has a high potential for evaluating sustainability for other watersheds worldwide.


Assuntos
Conservação dos Recursos Hídricos , Água Potável , Irã (Geográfico)
9.
Sci Total Environ ; 790: 148231, 2021 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-34380239

RESUMO

Studies have recently focused on microplastics (MPs) in tap and drinking water. Directly comparing the results of different studies is difficult owing to the use of various methodologies. In particular, a study of particles on a part of the filter to reduce the analysis time can lead to uncertainty regarding the number of MPs in tap water. In this study, the analysis of particles on the whole filtration area using a Fourier-transform infrared (FTIR) microscope was achieved in approximately 1 h using a filtration unit with a smaller filtration area (0.13 cm2) and a large-opening (26 µm) filter. Forty-two samples collected from five countries were analyzed using this method. The concentrations of the MPs at each site ranged from 1.9 to 225 particles L-1, with a mean concentration of all samples of 39 ± 44 particles L-1. The size ranged from 19.2 µm to 4.2 mm. Fragments were the predominant shape while fibers and spheres were also observed. Based on a combination of the shape, size, and chemical composition of the MPs, we discussed their sources. The MPs could have caused contamination after processing by a water treatment plant because we detected a significant number of polyester fibers > 100 µm, which were previously detected in the air, and PVC fragments > 50 µm, which are often used in water pipes. This study proposed technical improvements to the whole filtration area technique to detect MPs in tap water.


Assuntos
Água Potável , Poluentes Químicos da Água , Água Potável/análise , Monitoramento Ambiental , Microplásticos , Plásticos , Poluentes Químicos da Água/análise
10.
Artigo em Inglês | MEDLINE | ID: mdl-34444201

RESUMO

Nontuberculous mycobacteria (NTM) are ubiquitous microorganisms naturally resistant to antibiotics and disinfectants that can colonize drinking water supply systems. Information regarding the spread of NTM in specifically South America and Colombia is limited. We aimed to identify and characterize NTM present in tap water samples from Cali, Colombia. Drinking water samples and faucet biofilm swabs were collected in 18 places, including the city's three main water treatment plants (WTPs). Filter-trapped material and eluates (0.45 µm) from swab washes were plated in 7H11 agar plates. Suspected colonies were evaluated microscopically, and NTM species were identified based on the rpoB gene. Antibiotic susceptibility testing was also performed. Fifty percent (9/18) of sampling points were positive for NTM (including two WTPs), from which 16 different isolates were identified: Mycobacterium mucogenicum (8/16), M. phocaicum (3/16), M. chelonae (2/16), M. mageritense (2/16), and M. fortuitum (1/16), all rapidly growing mycobacteria. A susceptibility profile was obtained from 68.75% (11/16) of the isolates. M. chelonae was the most resistant species. All NTM isolated are potentially responsible for human diseases; our findings might provide a baseline for exploring NTM transmission dynamics and clinical characterization, as well as potential associations between NTM species found in drinking water and isolates from patients.


Assuntos
Água Potável , Infecções por Mycobacterium não Tuberculosas , Colômbia , Humanos , Mycobacteriaceae , Infecções por Mycobacterium não Tuberculosas/epidemiologia , Micobactérias não Tuberculosas/genética
11.
Wiad Lek ; 74(7): 1587-1594, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34459756

RESUMO

OBJECTIVE: The aim: The study aimed to assess the content of selected toxic compounds in mineral and spring waters available on the Polish market regarding potential health risks to consumers. PATIENTS AND METHODS: Materials and methods: Selected mineral and spring waters available on the Polish market were the study's objects. The content of such chemical compounds as arsenic, cadmium, lead, copper, and mercury in selected mineral and spring waters was analyzed. The content of metals in the samples was determined by inductively coupled plasma mass spectrometry (ICP-MS). Additionally, a literature review was performed to determine nitrates contamination of bottled waters available on the Polish market. Based on the collected data, an assessment of exposure and health risk to consumers was performed. RESULTS: Results: Arsenic had the highest mean concentration in the analyzed water samples. Consumption of such contaminated waters may be a significant health risk factor for consumers. Literature data indicate a relatively low content of nitrates in bottled waters available on the Polish market. Consumption of such mineral waters is not a significant source of exposure and does not translate into a significant health risk for consumers. CONCLUSION: Conclusions: To ensure consumers' health safety, there is a need to monitor the content of potentially harmful compounds in mineral and spring waters available on the Polish market.


Assuntos
Arsênio , Água Potável , Mercúrio , Águas Minerais , Arsênio/análise , Arsênio/toxicidade , Humanos , Minerais
12.
Bull Environ Contam Toxicol ; 107(3): 433-440, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34347116

RESUMO

The occurrence of Helicobacter spp. and fecal bacterial contamination was investigated in high-altitude environments from the Northeastern Andes of Venezuela. Helicobacter DNA was detected by PCR in streams, drinking and irrigation waters, and one culture from drinking water by the HP enrichment medium for selection of Helicobacter pylori, which displayed 98.98% homology to this pathogen based on 16S rRNA gene sequencing. FISH demonstrated predominant coccoid cells of the target bacteria indicative of the viable but nonculturable (VBNC) state in all water samples and HP cultures. Our work reveals for the first time Helicobacter spp. in waters from one of the highest places in the world. These results, together with the presence of fecal coliforms (2-160 MPN/100 mL) from the headwaters of rivers to drinking and irrigation waters, alert fecal contamination and epidemiological implications in this area of ecological and economic importance for the region.


Assuntos
Água Potável , Helicobacter pylori , Helicobacter , Altitude , DNA Bacteriano , Helicobacter/genética , Helicobacter pylori/genética , RNA Ribossômico 16S/genética , Microbiologia da Água
13.
Ecotoxicol Environ Saf ; 223: 112572, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34352571

RESUMO

Epidemiological studies have associated chronic exposure to arsenic (As) from drinking water with increased risk of hypertension. However, evidence of an association between As exposure from food and hypertension risks is sparse. To quantify the association between daily As intake from both food (rice, wheat and potatoes) and drinking water (Aswater) along with total exposure (Astotal) and hypertension risks in a study population in Bihar, India, we conducted an individual level cross-sectional analysis between 2017 and 2019 involving 150 participants. Arsenic intake variables and three indicators of hypertension risks (general hypertension, low-density lipoprotein (LDL) and high-density lipoprotein (HDL)) were derived, and any relationship was quantified using a series of crude and multivariable log-linear or logistic regression models. The prevalence of general hypertension was 40% for the studied population. The median level of HDL was 45 mg/dL while median value of LDL was 114 mg/dL. Apart from a marginally significant positive relationship between As intake from rice and the changes of LDL (p-value = 0.032), no significant positive association between As intake and hypertension risks could be ascertained. In fact, Astotal was found to be associated with lower risks of general hypertension and higher levels of HDL (p-value = 0.020 and 0.010 respectively) whilst general hypertension was marginally associated with lower Aswater (p-value = 0.043). Due to limitations regarding study design and residual confounding, all observed marginal associations should be treated with caution.


Assuntos
Arsênio , Água Potável , Hipertensão , Poluentes Químicos da Água , Arsênio/análise , Arsênio/toxicidade , Estudos Transversais , Água Potável/análise , Exposição Ambiental/efeitos adversos , Exposição Ambiental/análise , Contaminação de Alimentos/análise , Humanos , Hipertensão/induzido quimicamente , Hipertensão/epidemiologia , Índia/epidemiologia , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
14.
J Environ Radioact ; 237: 106720, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34454249

RESUMO

A hybrid extractive scintillating resin (HESR) was developed for the concentration and detection of radiocesium. The HESR comprised a cesium-selective potassium ferrierite ion-exchange powder embedded in porous polymeric scintillating beads. It was prepared by carrying out suspension polymerization of 4-methylstyrene with divinylbenzene, 2-(1-naphthyl)-4-vinyl-5-phenyloxazole fluor and ferrierite-K powder. A translucent column packed with the HESR was placed in a commercial flow-cell radiation detector for real-time detection of radiocesium. Measurements using the HESR detection system were compared with an on-line gamma-ray measurement using a NaI:Tl well detector containing a column of ferrierite-K powder/SiO2 or potassium-nickel ferrocyanate-polyacrylonitrile (KNiFC-PAN). The NaI:Tl well detector configuration quantified the gamma-ray from 137mBa, while the flow-cell detector primarily quantified the beta particles and conversion electrons of 137Cs. The minimum detectable concentration of the two detection modalities were calculated and shown to be lower than the maximum contaminant level in drinking water of 7.4 Bq/L (200 pCi/L).


Assuntos
Água Potável , Monitoramento de Radiação , Partículas beta , Césio , Dióxido de Silício
15.
J Water Health ; 19(4): 616-628, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34371498

RESUMO

Many Cameroonian cities lack access to potable drinking water where populations rely on alternative water sources of doubtful quality. This study aimed at describing the trends and patterns of waterborne diseases (WBDs) reported in some health facilities in Bamboutos Division between 2013 and 2017 as baseline data towards understanding the profile of WBDs in this area. A retrospective review of clinical data kept on patients who visited the main health facilities in Bamboutos Division from January 2013 to December 2017 was conducted. Overall, 39.1% (n = 8,124) of total patients were positive for at least one WBD. Categories of WBDs were dysenteries (18.6%), gastroenteritis (4.2%), viral hepatitis (0.2%) and typhoid was the most preponderant (24.4%). The most affected age groups were those above 24 years but significant differences were observed only in 2013 and 2017. Distribution of potential WBDs was locality dependent. The highest prevalence of typhoid fever was recorded in Bameboro (35.4%), dysenteries in Bamedjinda (20.4%) and gastroenteritis (17.3%) in Bamekoumbou. The study shows very high overall prevalence of WBDs in some localities which could be considered as 'hotspots' of WBDs in Bamboutos. This suggests the urgent need for setting up measures to tackle the challenges of potable drinking water supply.


Assuntos
Água Potável , Doenças Transmitidas pela Água , Adulto , Camarões/epidemiologia , Instalações de Saúde , Humanos , Estudos Retrospectivos , Microbiologia da Água , Poluição da Água , Abastecimento de Água , Doenças Transmitidas pela Água/epidemiologia , Adulto Jovem
16.
Artigo em Inglês | MEDLINE | ID: mdl-34360286

RESUMO

Chemical pollution in the transboundary Langat River in Malaysia is common both from point and non-point sources. Therefore, the water treatment plants (WTPS) at the Langat River Basin have experienced frequent shutdown incidents. However, the Langat River is one of the main sources of drinking water to almost one-third of the population in Selangor state. Meanwhile, several studies have reported a high concentration of Arsenic (As) in the Langat River that is toxic if ingested via drinking water. However, this is a pioneer study that predicts the As concentration in the Langat River based on time-series data from 2005-2014 to estimate the health risk associated with As ingestion via drinking water at the Langat River Basin. Several time-series prediction models were tested and Gradient Boosted Tree (GBT) gained the best result. This GBT model also fits better to predict the As concentration until December 2024. The mean concentration of As in the Langat River for both 2014 and 2024, as well as the carcinogenic and non-carcinogenic health risks of As ingestion via drinking water, were within the drinking water quality standards proposed by the World Health Organization and Ministry of Health Malaysia. However, the ingestion of trace amounts of As over a long period might be detrimental to human health because of its non-biodegradable characteristics. Therefore, it is important to manage the drinking water sources to minimise As exposure risks to human health.


Assuntos
Arsênio , Água Potável , Poluentes Químicos da Água , Purificação da Água , Água Potável/análise , Monitoramento Ambiental , Humanos , Medição de Risco , Rios , Poluentes Químicos da Água/análise
17.
Artigo em Inglês | MEDLINE | ID: mdl-34360340

RESUMO

The supply of drinking water to the population is an important challenge facing humanity, since both surface and underground sources present a great variability of water storage with respect to space and time. This problem is further aggravated in arid and semi-arid areas where rainfall is low and torrential, which makes groundwater the main source of supply; therefore, it is necessary to carry out studies that allow evaluating the evolution of the quantity and quality of water. This study addresses the behavior of groundwater in a semi-arid region, considering the theory of flow systems to identify movement as well as water quality, es determined by a water quality index (WQI), calculated considering arsenic and fluorine. In addition, a quality irrigation classification is used, employing the norms in accordance with international standards and the Mexican Norm, which allows for a comparison. Local, regional, intermediate and mixed flow systems are identified, and the evolution of cations and anions in addition to temperature is examined. It is observed that the drinking water quality index classifies them as excellent in most of the monitored wells (<50), but with a negative evolution. Regarding irrigation, most of the water samples are classified without restriction for the establishment of any type II crop (C2S1) and with restrictions for horticultural crops. It is observed that arsenic had values between 0.49 and 61.40 (µg/L) in 2005, while in 2015 they were between 0.10 and 241.30 (µg/L). In addition, fluoride presented values between 0.00 and 2.6 (mg/L) in 2005, while in 2015 they were between 0.28 and 5.40 (mg/L). The correlations between arsenic and fluorine are noted as well as WQI and SAR. A finding in this research was to include arsenic and fluorine in the calculation of the WQI allowing a better interpretation of the quality of water for both human consumption and for agricultural use to based on this make the best decision to control any harmful effects for the population, in addition to identifying the appropriate purification treatment required to control pollutants. It is concluded that arsenic is an element of utmost importance when considering water quality, so it is necessary to examine its evolution and continue to monitor its levels constantly.


Assuntos
Arsênio , Água Potável , Água Subterrânea , Poluentes Químicos da Água , Arsênio/análise , Água Potável/análise , Monitoramento Ambiental , Humanos , Poluentes Químicos da Água/análise , Qualidade da Água , Abastecimento de Água
18.
Environ Monit Assess ; 193(8): 546, 2021 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-34338921

RESUMO

The study focused on assessing drinking water quality from different sources in Gweru urban. Seventy six samples were collected from 6 different locations and analysed for physicochemical parameters and microbial quality. Bacteria isolates were identified using matrix-assisted laser desorption ionization-time of flight mass spectrometry and antibiotic susceptibility was determined for 4 isolates that had been identified as Escherichia coli (2) and Salmonella spp. (2). Although most samples were within World Health Organisation limits for most parameters, none met coliform limits. pH ranged between 6.2 and 6.9. Salmonella prevalence was 2%. Escherichia coli and Salmonella spp. isolates were resistant to at least three antibiotics. The study showed inconsistent water quality across the city and contamination in alternative water sources.


Assuntos
Água Potável , Escherichia coli , Resistência Microbiana a Medicamentos , Monitoramento Ambiental , Salmonella , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Qualidade da Água , Zimbábue
19.
Artigo em Inglês | MEDLINE | ID: mdl-34360177

RESUMO

The United States Environmental Protection Agency monitors contaminants in drinking water and consolidates these results in the National Contaminant Occurrence Database. Our objective was to assess the co-occurrence of metal contaminants (total chromium, hexavalent chromium, molybdenum, vanadium, cobalt, and strontium) over the years 2013-2015. We used multilevel Tobit regression models with state and water system-level random intercepts to predict the geometric mean of each contaminant occurring in each public water system, and estimated the pairwise correlations of predicted water system-specific geometric means across contaminants. We found that the geometric means of vanadium and total chromium were positively correlated both in large public water systems (r = 0.45, p < 0.01) and in small public water systems (r = 0.47, p < 0.01). Further research may address the cumulative human health impacts of ingesting more than one contaminant in drinking water.


Assuntos
Água Potável , Poluentes Químicos da Água , Água Potável/análise , Humanos , Estados Unidos , United States Environmental Protection Agency , Água , Poluentes Químicos da Água/análise , Abastecimento de Água
20.
Water Res ; 203: 117496, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34399246

RESUMO

UVC disinfection has been recognised by the WHO as an effective disinfection treatment to provide decentralized potable water. Under real conditions there are still unknowns that limit this application including the influence of suspended solids and natural organic matter. This work aims to investigate the influence of two key parameters, suspended solids and natural organic matter, on the efficiency of UVC disinfection of surface water to achieve the drinking water quality requirements established by the WHO for point of use (POU) technologies. Kaolinite (turbidity agent) and humic acids (HA, model of organic matter) were used in a factorial design of experiments (Turbidity from 0 to 5 NTU, and HA from 0 to 3.5 mg/L) to investigate their effect on UVC inactivation of MS2 phage in surface water. A collimated beam (12 W) and a commercial UVC disinfection flow system (16 W) designed to provide drinking water at households were used. The UVC flow system both in the laboratory and in the field was able to achieve the reduction requirements established by WHO (LRV >3.5 for all tested conditions), confirming the good performance of the studied UVC disinfection system. The results found in the lab were used to establish a numerical model that predicts the disinfection rate constant as a function of water turbidity and transmittance at 254 nm (confidence level>95%). The model permitted to elucidate the critical effect of low concentrations of HA in reducing the inactivation rate by 40% for 3.5 mg/L-HA compared with 0, the non-significant detrimental effect of turbidity lower than 5 NTU, and the lack of synergistic effects between both parameters at these levels. The UVC flow system was also tested in the field, in Tzabalho, Chiapas (Mexico), and Antioquia (Colombia), with spiked MS2 into natural surface water. This investigation opens a potential application to monitor the performance of UVC systems with surface water by monitoring transmittance at 254 nm as a tool to control UVC domestic systems to deliver safe drinking water in a household without the need of expensive and laborious biological monitoring tools.


Assuntos
Água Potável , Purificação da Água , Desinfecção , Levivirus , Raios Ultravioleta
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