Drinking Water Intake Research Articles

Water quality and probabilistic non-carcinogenic health risk of groundwater: a half decadal scenario change in Vadodara.

Groundwater is essential to secure the safety of water supply in Vadodara, Gujarat. In this study, groundwater samples were collected from various part of the city which separated in 12 wards. The present study contains analyses of 720 groundwater samples gathered from various tube and open wells and analyzed for fluoride and other physicochemical parameters during 2014 and 2019. The results indicated that fluoride and TDS were high and the overall water quality was poor in the study area. Gastrointestinal and other health-related issues increased due to higher TDS in east, north and northeast regions. Likewise, hierarchical cluster analysis also indicated that TDS and chloride-rich water. Fluoride concentration was observed in the range of 0.66-1.61mg/l (2014) and 0.86-1.77mg/l (2019) which indicates that 62% samples are unfit for drinking purpose, which could cause dental and skeletal fluorosis. The water quality index (WQI) indicated lack of excellent water in the studied area in the last half-decade. As per WQI calculation suggest that 82.12% (2014) and 69.00% (2019) of groundwater samples represent poor, very poor and unsuitable categories, whereas remaining 17.85% (2014) and 31.00% (2019) of the samples represent good category for drinking purposes in entire Vadodara, Gujarat. Marginal improvement in the groundwater quality is reported due to good rainfall in 2019. Health risks associated with high fluoride drinking water were assessed for various age groups of inhabitants such as children, infants and adults. The non-carcinogenic hazard quotient estimated by oral intake was 1.38-3.36 (2014) and 1.79-3.70 (2019) for infants; 0.69-1.68 (2014) and 0.90-1.85 (2019) for children, whereas 0.07-0.18 (2014) and 0.10-0.20 (2019) for adults. Therefore, infant and children are relatively at higher health risk due to the intake of fluoride-rich drinking water than adult in the studied region. Both indices were indicated contaminated water or closer to contamination which induced non-carcinogenic health risk on citizens. Thus, the comprehensive results of present study can be used as a baseline data and valuable tool for government authorities for long-term monitoring, health monitoring and sustainable development of Vadodara, Gujarat.

Contribution of household drinking water intake to arsenic and lead exposure among Uruguayan schoolchildren

BackgroundFood and water are common exposure sources of arsenic and lead among children. Whereas dietary sources of these toxicants are fairly well-studied, the contribution of drinking water to toxicant exposures is not well characterized in many populations, particularly in the Global South. ObjectiveTo assess the extent to which consumption of household drinking water contributes to arsenic and lead exposure among Uruguayan schoolchildren with low-level exposure. MethodsChildren, aged 5–8 years, were enrolled into the Salud Ambiental Montevideo study during 2009–2013 from schools in Montevideo, Uruguay. Participants reported water intake as part of two 24-h dietary recalls. Concentrations of arsenic were measured in first morning void urine samples, and adjusted for urinary specific gravity. Lead concentrations were measured in venous blood samples. Drinking water samples were collected from participants’ homes and toxicant concentrations measured. Data analyses involved a triangulation approach. First, multivariable linear regressions estimated the associations between toxicant exposure through drinking water, calculated for each child as the product of water intake and water toxicant concentration, and the respective toxicant biomarker concentrations among children with complete data on all variables (Sample A; n = 40). Second, regressions were repeated for participants with complete data on all variables except water intakes (Sample B; n = 195), after water intakes were imputed. Finally, models were constructed for participants of Sample B (n = 195) based on drinking water intakes assumed to be fixed at 25th, 50th, 75th percentile intakes of participants in sample A. ResultsToxicant exposure via drinking water intake was low. The triangulation approach revealed no associations between toxicant exposure through household water intake and the respective toxicant biomarker concentrations. ConclusionStudies with larger samples and repeated measures are needed to confirm these findings. Nevertheless, it appears that at low water toxicant concentrations, typical water consumption is not a major contributor to children's exposure.

Preference and discrimination behaviour of llamas to saline drinking water

Global climate changes increase the risk of salinization of soil and water imposing possible health risks on livestock, especially in arid and semi-arid regions such as the Andes, the habitat of wild and domestic South American camelids (SAC), e.g. the llama (Lama glama). The aim of the present study was to evaluate the sensitivity and tolerance of llamas towards different NaCl concentrations in their drinking water. In total, 12 adult females with an average body weight (BW) of 140 kg ± 20.6 kg were kept under controlled conditions in individual pens. After a control phase (1 week) providing only fresh water, two choice tests were consecutively conducted: (1) a pairwise preference test (3 weeks) offering one bucket with fresh water and another with stepwise increasing NaCl concentration (0.25, 0.5, 0.75, 1.0, 1.25, 1.5 %) and (2) a free-choice test (3 weeks) during which six buckets were simultaneously offered with NaCl concentrations of 0, 0.25, 0.5, 0.75, 1.0, and 1.25 % NaCl. Chopped hay, water and a salt lick were provided for ad libitum intake. Records were kept on BW, body condition, feed, water and Na intake. Dry matter intake, total water and Na intakes increased during both choice tests (P < 0.001). Daily total Na intakes relative to metabolic body size (g/kg0.75) averaged 0.04 ± 0.02, 0.19 ± 0.02 and 0.26 ± 0.02 during the control phase, the preference and the free-choice test, respectively. In the pairwise test, llamas showed a weak preference for saline water with 0.5 – 0.75 % NaCl, and rejected water from 1.25 % NaCl. During the free-choice system, llamas had a remarkable interest in saline water with shares from total drinking water intake for fresh water and concentrations of 0.25, 0.50, 0.75, 1.0 and 1.25 % NaCl being 23.6, 21.2, 19.5, 13.8, 13.3 and 8.6 %, respectively. Llamas demonstrated a similar capacity to differentiate between saline water concentrations in two different experimental setups and adjusted their Na intake in self-selection. The results suggest that their reactions to saline water are similar to those of goat breeds adapted to arid zones.

Drinking Water Source and Intake Are Associated with Distinct Gut Microbiota Signatures in US and UK Populations

BackgroundThe microbiome of the digestive tract exerts fundamental roles in host physiology. Extrinsic factors including lifestyle and diet are widely recognized as key drivers of gut and oral microbiome compositions. Although drinking water is among the food items consumed in the largest amount, little is known about its potential impact on the microbiome. ObjectivesWe explored the associations of plain drinking water source and intake with gut and oral microbiota compositions in a population-based cohort. MethodsMicrobiota, health, lifestyle, and food intake data were extracted from the American Gut Project public database. Associations of drinking water source (bottled, tap, filtered, or well water) and intake with global microbiota composition were evaluated using linear and logistic models adjusted for anthropometric, diet, and lifestyle factors in 3413 and 3794 individuals, respectively (fecal samples; 56% female, median [IQR] age: 48 [36–59] y; median [IQR] BMI: 23.3 [20.9–26.3] kg/m2), and in 283 and 309 individuals, respectively (oral samples). ResultsDrinking water source ranked among the key contributing factors explaining the gut microbiota variation, accounting for 13% [Faith's phylogenetic diversity (Faith's PD)] and 47% (Bray–Curtis dissimilarity) of the age effect size. Drinking water source was associated with differences in gut microbiota signatures, as revealed by β diversity analyses (P < 0.05; Bray–Curtis dissimilarity, weighted UniFrac distance). Subjects drinking mostly well water had higher fecal α diversity (P < 0.05; Faith's PD, observed amplicon sequence variants), higher Dorea, and lower Bacteroides, Odoribacter, and Streptococcus than the other groups. Low water drinkers also exhibited gut microbiota differences compared with high water drinkers (P < 0.05; Bray–Curtis dissimilarity, unweighted UniFrac distance) and a higher abundance of Campylobacter. No associations were found between oral microbiota composition and drinking water consumption. ConclusionsOur results indicate that drinking water may be an important factor in shaping the human gut microbiome and that integrating drinking water source and intake as covariates in future microbiome analyses is warranted.

Human exposure to phthalate esters via ingestion of municipal drinking water from automatic water purifiers: levels, sources, and risks

The presence of organic pollutants in drinking water is an environmental problem threatening public health.

Fluoride Contamination in Groundwater and Its Effect on Human Health: Case Study of Baramati Tehsil Area, India

Baramati Tehsil is the rural part of the Pune district which have an arid to semi-arid region. Groundwater is the main source of drinking water for the people living in this area. The groundwater is being removed from a dug well and borewells in the study area for drinking purposes. The present study studied, fluoride from Dug well water of the Baramati Tehsil area. A total of 15 groundwater samples of dug well were collected in post-monsoon (POM) winter 2015 to pre-monsoon (PRM) summer 2017 for four seasons by using standard methods of American Public Health Association (APHA). The various physico-chemical parameters such as pH, Electrical conductivity (EC), Total Dissolved Solids (TDS), Total Hardness (TH), Calcium (Ca2+), Magnesium (Mg2+), Sodium (Na+), Potassium (K+), Bicarbonate (HCO3-), Chloride (Cl-), Sulphate (SO42-) and Fluoride (F-) were determined using standard procedures of APHA suggested for determination of the water quality for drinking purpose. The results obtained from the analysis was used for interpretation of fluoride and other ions concentration and the effect on human health. Results obtained indicate that the fluoride concentrations in POM and PRM were within the maximum permissible limit of WHO and BIS recommended for drinking. World Health Organization (WHO 2006) has fixed a safe limit of fluoride from 0.5 to 1.5 mg/l in drinking water. The maximum fluoride concentration in the study area was 0.68 mg/l while the minimum was 0.12 mg/l and the average fluoride concentration was 0.41 mg/l in all four seasons. The drinking water intake with fluoride content less than 0.5 mg/l can cause tooth decay. The groundwater of all wells was suitable for drinking purposes without treatment for fluoride removal at the time of analysis.

Evaluation of Gross Alpha and Beta Activity Concentrations and Annual Effective Dose in Drinking Waters of Misan Province-Iraq Using Low Background Gas Flow Proportional Counter (LB- 4110)

In this study, assessment of levels natural radioactivity in drinking water samples of Misan Province of Iraq was carried out. A total of 33 (Tigris river, station and Tap) water samples collected from eleven places in Misan Province of Iraq. The beta and alpha gross radioactivity of the samples water was measured and an average annual effective dose derived of drinking-water ingestion was estimation utilizing new model a LB-4110 low background gas flow proportional counter. The data indicated that the Beta and Alpha gross activities and annual effective dose in samples did not exceed WHO recommended levels (0.5 Bq/L of Alpha gross, 1.0 Bq/L of Beta gross and 0.1 mSv/y for annual effective dose).

The Identification of Risks for Drinking Water Intakes in Urbanized Area: The Case Study of Toruń (Central Poland)

This article discusses the problem of natural hazards connected with climatic changes and their influence on water safety. A medium-sized town in central Poland which is supplied with consumption water from both underground water intakes and surface water resources was selected as a case study. Natural hazards, such as droughts or floods, were identified and the risk of the occurrence of natural hazards concerning water supply systems assessed. The findings of the archived data analysis for the period 1971–2020 helped to identify extreme circumstances, the occurrence of which had an impact on secure water supplies in terms of quantity. Moreover, the results obtained indicate that the greatest influence had all the situations connected with the Drwęca low water discharge, which in the long term could lead to temporary water shortages. In the analyzed period, there was a significant increase in the number of days without precipitation, together with a statistically significant increase in the average annual air temperature. Meteorological hazards related to days without precipitation far outweighed the occurrence of days with intense precipitation. The analysis of water table fluctuations observed at the Jedwabno infiltration intake showed a high sensitivity of the aquifer to atmospheric conditions.

Effects of mild water restriction on nutrient digestion and protein metabolism in desert-adapted goats

• Mildly restricting drinking water intake by ≤ 21 % does not reduce feed intake in desert-adapted goats. • Declining drinking water intake enhances rumen fermentation, but reduces microbial growth. • Lowering drinking water intake shifts nitrogen excretion from urine to faeces. • Effects of drinking water restriction differ depending on diet and animal factors. The aim of the present study was to determine the effects of mild drinking water restriction ( WR ) on feed intake, diet digestibility, rumen fermentation, and nitrogen ( N ) balance in a desert-adapted goat breed of Oman. Two feeding trials were conducted during the dry summer months (August-October) in 2013 and 2014. In each trial, nine adult male Batinah goats were exposed to two levels of mild WR (WR: 85 % (WR15) and 70 % (WR30) of individual ad libitum consumption; 100 % (WR0)) in a 3 × 3 Latin Square design. Drinking water intake, feed offered and refused, and excretion of urine and faeces were quantified and samples analysed for crude nutrient and fibre fractions. Moreover, rumen microbial protein synthesis was estimated from urinary purine derivatives excretion. In trial 2, rumen fermentation characteristics were additionally studied in three rumen-fistulated goats. Linear and quadratic effects of WR in each trial were assessed by mixed model analysis, whereas correlations between drinking water intake and response variables were determined across both trials. For WR30, drinking water intake was 79 % and 90 %, respectively, of the water intake of WR0 goats in trial 1 and WR15 goats in trial 2. Water restriction had no effect on feed intake, rumen microbial protein synthesis, and N balance in both trials. However, apparent total tract digestibilities of neutral and acid detergent fibre tended to decrease linearly ( p ≤ 0.081) with increasing WR level in trial 1, whereas those of dry matter and organic matter were lower ( p ≤ 0.028) for WR15 than for WR0 and WR30 in trial 2. Proportions of butyrate ( p ≤ 0.046) and isovalerate ( p = 0.087) in rumen fluid were greater and those of propionate ( p = 0.079) and valerate ( p = 0.062) lower for WR30 as compared to one or both of the other WR levels. Duodenal microbial N flow and efficiency of microbial protein synthesis did not differ between WR levels. Yet, across both trials, both variables correlated positively with drinking water intake. Similarly, declining drinking water intake increased the ratio between faecal and urine N excretion (r=−0.55) and the N concentration in faeces (r=−0.42), but reduced the fibre concentration (r=0.38) and the proportion of undigested feed N in faeces (r=0.49). Mild restriction of drinking water intake to ≥ 79 % of the ad libitum consumption, which is expected to occur more frequently with advancing climate change in the semi-arid tropics and subtropics, may impair feed nutrient use and thus performance of regionally adapted small ruminants, while improving the quality of their manure.

Influence of the addition of water to total mixed rations on the feeding behaviour, feed intake and milk performance of high-yielding dairy cows

The goal of this study was to investigate the influence of the addition of water to total mixed rations (TMR) with a dry matter (DM) content of 42 - 47% and high proportions of ensiled forage on feeding behaviour, DM intake (DMI) and milk performance, as well as changes in TMR temperature. The underlying hypothesis was a reduction in the selective feeding behaviour and a resulting increase in DMI of the cows, which were provided with a moist TMR. During two feeding trials, 48 German Holstein cows per trial were split into 2 groups (Trial I, winter: 85 ± 28 d in milk (DIM); Trial II, summer: 67 ± 34 DIM). Both trials were set up as a crossover design with period lengths of 45 (Trial I) and 35 (Trial II) d. The rations in each trial were made of the same components, had the same energy and nutrient concentrations and had slightly different DM contents. In Trial I, a TMR with 46.4% DM (dry TMR) was mixed with 12.5 kg water per cow per day, to reduce the DM content of the TMR to 37.3% DM (wet TMR). In Trial II, the DM content of 41.8% (dry TMR) was reduced to 33.9% (Wet TMR) after 14 kg of water per cow per day were added. The DMI of the individual animals and their milk yield were measured daily, and the milk composition was determined weekly. To judge the feeding behaviour, samples were taken from each feeding group at five points throughout the day during Trial I, and three during Trial II. The samples were tested for particle size distribution using a Penn State Particle Separator (PSPS). In both trials, the selective feeding behaviour was reduced as a consequence of the addition of water to TMR. In the case of the dry TMR, a change in particle size distribution in the troughs was already discernible 10 h after the feed was provided. In both trials, the addition of water had a positive influence on the DMI. In Trial I, the cows consumed 1.3 kg DM/d more as a consequence of the addition of water (p < 0.001), and in Trial II the difference equated to 0.6 kg DM/d after the addition of water (p < 0.001). The increased energy and nutrient intake of the cows that had been fed with the moistened TMR led to higher daily milk yield (Trial I: +0.6 kg/d; Trial II: +0.5 kg/d) and drinking water intake (p < 0.001). During the first 24 h after mixing the rations in Trial II (summer), no temperature differences were observed between the dry and moistened TMR. During the time period of 24–48 h after feeding, the dry TMR had an average temperature of 36.8 °C and the wet TMR had a temperature of 40.1 °C, which was a significant difference (p < 0.001). Furthermore, in Trial II, the increased energy and nutrient intake was reflected in a higher fat and protein yield and in an increased energy-corrected milk yield by 0.8 kg/d (p = 0.015). These results confirm that by adding water to TMR, selective feeding behaviour can be reduced and DMI increased, both during summer and winter trials. The importance of a uniform, non-selective feed intake in high-performing dairy cows is also evident from the results.

Empirical equations for drinking water intake prediction of growing lambs: Meta-analysis

A meta-analysis was conducted to develop and evaluate new empirical predictive models for drinking water intake (DWI) of growing lambs. A large dataset containing 213 experimental diets from 47 experiments published in 44 peer-reviewed papers was built. Selected explanatory variables were grouped into animal (bodyweight initial (BWi); body weight final (BWf); average daily gain (ADG); feed conversion ratio (FCR); nitrogen intake (Nint), diet composition (dry matter; ash; crude protein (CP); neutral detergent fiber; forage), dry matter intake (DMI) and total digestible nutrient (TDN) and/or total digestible nutrient intake (TDNI) inputs. To develop predictive models, the dataset (peer-reviewed papers) was randomly divided into two subsets for statistical analyses. The first data subset was used to develop equations to predict DWI (27 peer-review papers; 28 experiments; 139 experimental diets), and the second data subset was used to assess the adequacy of the predictive models (17 peer-review papers; 19 experiments; 74 experimental diets). Ash was the main diet input affecting DWI in growing lambs, while FCR affected DWI more than ADG and Nint among the animal inputs. For growing lambs, the use of predictor variables associated with energy requirements improved the accuracy of the models when compared to those which used DMI. Among the developed models, the complete ones, which include diet and animal input, present better predictive quality. The use of the Diet + Animal Ib Model is recommended for the prediction of DWI in growing lambs.

Total and drinking water intake and risk of all-cause and cardiovascular mortality: A systematic review and dose-response meta-analysis of prospective cohort studies.

Understanding the association between water consumption and mortality is important for guiding consumers and prioritizing dietary guidelines to reduce the risk. Therefore, in the current study, we conducted a systematic review and dose-response meta-analysis of prospective cohort studies to summarise the association between total water and drinking intake and risk of mortality from all causes and CVD. A comprehensive search was performed on PubMed/Medline, Scopus, and ISI Web of Science up to February 2020. The random-effects model was used to calculate the pooled effect size (ES) and 95% confidence interval. Seven prospective cohort studies were included in the systematic review and meta-analysis. During the follow-up period of 6 to 19.1years, 14754 deaths (7611 from cardiovascular disease) occurred among 116816 participants. No significant association was found between drinking water intake and all-cause mortality (ES: 0.82; 95% CI: 0.63-1.08, I2 =77.3%, P=.16). Total water intake was not associated with all-cause mortality (ES: 0.94; 95% CI: 0.82-1.08, I2 =66.5%, P=.41). However, a significant inverse association was seen between total water intake and risk of CVD mortality (ES: 0.86; 95% CI: 0.78-0.95, I2 =0%, P=.002). Linear dose-response meta-analysis revealed a significant inverse association between total water intake and all-cause mortality by an additional one cup per day (pooled ES: 0.98; 95% CI: 0.97-0.99, P=.001). Furthermore, each additional cup of total water intake per day was associated with a 3% lower risk of death from CVD (pooled ES: 0.97; 95% CI: 0.96-0.98, P<.001). High consumption of total water is associated with a lower risk of CVD mortality. However, total water intake was not associated with risk of all-cause mortality.

Microbial modelling of Lake St. Clair: Impact of local tributaries on the shoreline water quality

Fecal contamination of surface water resource is a major health concern primarily due to the potential for pathogenic organisms to be transmitted to human by contaminated water. In lake-wide modelling of large lakes with many sources of microbial contamination, minor contributions from small tributaries are generally ignored. In this study, we applied a three dimensional high-resolution hydrodynamic and water quality model to assess the impact of eight smaller tributaries located on the southern edge of Lake St. Clair on microbial water quality during the summer of 2016. The impact at two beaches and two drinking water intakes located in the nearshore region of the southern edge of Lake St. Clair was considered. Results reveal that the microbial water quality in the nearshore regions close to these eight small tributaries' confluence are significantly affected by one or more of these tributaries. Although this effect is captured by our model with a time-variable or constant decay rates, the use of time-variable decay may be preferable for dynamic simulations over time. The total flow contribution from the smaller tributaries was estimated in the range of 18-35% while that for E. coli concentration was >80%. Three small tributaries were also predicted to account for >70% of the E. coli concentrations at drinking water intakes. For tributaries that do not significantly affect the hydrodynamics in a lake, a new framework is presented to identify approximate influence zones for microbial pollution that can help determine if a given location is likely to be impacted by the inflowing tributaries.

Using machine learning classification to detect simulated increases of de facto reuse and urban stormwater surges in surface water

Water quality events such as increases in stormwater or wastewater effluent in drinking water sources pose hazards to drinking water consumers. Stormwater and wastewater effluent enter Lake Mead—an important drinking water source in the southwest USA—via the Las Vegas Wash. Previous studies have applied machine learning and online instruments to detect contamination in water distribution systems. However, alert systems at drinking water intakes would provide more time for corrective action. An array of online instruments measuring pH, conductivity, redox potential, turbidity, temperature, tryptophan-like fluorescence, UV absorbance (UVA254), TOC, and chlorophyll-a was fed raw water directly from Lake Mead. Wastewater effluent, dry weather Las Vegas Wash, and storm-impacted Las Vegas Wash samples were blended into the instrument inlets at known ratios to simulate three types of adverse water quality events. Data preprocessing was conducted to correct for diurnal patterns or instrument drift. Supervised machine learning was conducted using previously published models in R. Ninety-nine models were screened on the raw data. Eight high-performing models were evaluated in-depth and optimized. Weighted k-Nearest Neighbors, Single C5.0 Ruleset, Mixture Discriminant Analysis, and an ensemble of these three models had accuracy over 97% when assigning test set data among three classes (Normal, Event, or Maintenance). The ensemble detected all event types at the earliest timepoint and had one false positive that was not a lag error (i.e., consecutively following a true positive). Omitting Maintenance, the Adaboost model had over 99% test set accuracy and zero false positives that were not lag errors. Data preprocessing was beneficial, but the optimal methods were model-specific. All nine water quality variables were useful for most models, but UVA254 and turbidity were most important.

Lead, cadmium, mercury, and chromium in urine and blood of children and adolescents in Germany - Human biomonitoring results of the German Environmental Survey 2014-2017 (GerES V).

Metals reach humans through food and drinking water intake and inhalation of airborne particles and can have detrimental health effects in particular for children. The metals presented here (lead, cadmium, chromium, and mercury) could lead to toxic effects such as neurotoxicity, mutagenicity, and have been classified as (possible) carcinogens. Using population representative data from the German Environmental Survey 2014-2017 (GerES V) from 3- to 17-year-old children on lead and cadmium in blood (n=720) and on cadmium, chromium, and mercury in urine (n=2250) we describe current internal exposure levels, and socio-demographic and substance-specific exposure determinants. Average internal exposure (geometric means) in blood was 9.47μg/L for lead and below 0.06μg/L (limit of quantification) for cadmium, and in urine 0.072μg/L for cadmium, 0.067μg/L for mercury, and 0.393μg/L for chromium, respectively. Younger children have higher concentrations of lead and chromium compared to 14-17-year-old adolescents, and boys have slightly higher mercury concentrations than girls. With respect to substance specific determinants, higher lead concentrations emerged in participants with domestic fuel and in non-smoking children with smokers in the household, higher levels of cadmium were associated with smoking and vegetarian diet and higher levels of mercury with the consumption of seafood and amalgam teeth fillings. No specific exposure determinants emerged for chromium. The health based guidance value HBM-I was not exceeded for mercury and for cadmium in urine it was exceeded by 0.6% of the study population. None of the exceedances was related to substantial tobacco smoke exposure. Comparisons to previous GerES cycles (GerES II, 1990-1992; GerES IV, 2003-2006) indicate continuously lower levels.

Experience in application of modern technologies of measuring the structure of currents in the upstream waters of large hydroelectric complexes (on the example of the Kama HPP)

The creation of reservoirs on watercourses leads to significant changes in the hydrological regime of water bodies: it allows to smooth out the peaks of maximum water discharge during the flood period and to regulate low runoff. The reservoirs with a significant storage capacity enable to solve a wide range of water management problems, among which are: using the falling water energy for hydropower purposes, ensuring uninterrupted water supply and navigation. In view of the fact that dams are generally managed by hydropower companies, the regime for regulating downstream water mass discharges is often determined by the schedule of daily electricity consumption. Intraday changes in the volume of water discharge through the hydroelectric units of hydroelectric power plants form multidirectional flows in the upstream, which can affect the work of other water users. This paper examines the impact of intraday changes in flow rates of downstream water discharges on the dynamic and physical properties of the water mass in the area of the drinking water intake heads of the city of Perm.

Effects of chronic cadmium exposure on the structure and function of intestinal mucosal flora in mice

Cadmium (Cd) is a serious environmental pollutant to human health. Intestinal flora is associated with human health. This study probed into the effects of Cd on the small intestinal mucosal flora in mice by drinking water intake 5 ppm, 20 ppm and 100 ppm cadmium chloride for 50 days respectively. Results indicated that diversity, taxonomic composition and community structure of intestinal mucosal flora were influenced by Cd exposure. Sphingomonas, Microbacterium and Desulfovibrio, as the characteristic bacteria, played vital roles in the different dose groups of Cd. Meanwhile, Cd exposure adjusted the metabolic function of intestinal mucosal flora, mainly involved in the effects on carbohydrate, amino acid and lipid metabolism. Furthermore, different doses of Cd had different effects on the microbial activity of intestinal mucosal. Conclusively, Cd exposure affected the structure and function of intestinal mucosal flora. We screened the Sphingomonas, Microbacterium and Desulfovibrio as the biomarkers of intestinal mucosal flora after Cd exposure.

Forested lands dominate drinking water supply in the conterminous United States

Forests provide the most stable and highest quality water supplies among all land uses. Quantitatively evaluating the benefits of forest water supply functions is important to effectively mitigate the impacts of land development, climate change, and population growth. Here, by integrating a water balance model and national drinking water data, we determined the amount of surface water yield originating on different forest ownership types at a fine resolution (88,000 watersheds) and tracked that water through the river network to drinking water intakes and the populations they serve. We found that forested lands comprised 36% of the total land area but contributed 50% of the total surface water yield. Of the 23,983 public surface drinking water intakes depending on surface water sources, 89% (serving around 150 million people) received some (>0.01%) surface water from forested lands, and 38% (serving about 60 million people) received more than 50% of their surface drinking water supply from forested lands. Privately-owned forests were the most important water source in the eastern U.S., benefiting 16 million people, followed by federal forests (14.4% of the total water supply). In contrast, federally-owned forested lands were the dominant water source (52% of the total water supply) in the West. Privately-owned forests are the most vulnerable to future land use change and associated water supply impacts. Continuing programs that support private forest landowners with financial and technical assistance through federal and state forest management agencies and potentially developing payment for ecosystem service schemes could maximize benefits for landowners so they may retain their land assets while minimizing forest loss and associated impacts on critical ecosystem services including the provisioning a clean and reliable water supply for the American public.

Comparison of methods to evaluate overland travel times for source water protection

Protection areas are commonly delineated in water supply watersheds to manage anthropogenic activities that pose pollution risks. These areas are frequently determined based on geographical distances that are not representative of the travel time of water. For surface waters, the total travel time for water between an anthropogenic activity and the drinking water intake is the sum of the overland travel time and the travel time in a river. In previous research, we reported methods for evaluating travel time in a river. The present paper focuses on the estimation of overland travel times. Four methods were applied, evaluated and compared based on a land use database representing anthropogenic activities that potentially release contaminants. Methods for overland travel times that provided more precise results required abundant data and expertise to be implemented, but can contribute to improved decision-making for land use planning in the context of source water protection.

Probabilistic Risk Assessment of Arsenic Exposure Through Drinking Water Intake in Chinese Residents

The total arsenic concentrations of the three main drinking water types in China were determined through a systematic literature review. The distribution models of drinking water exposure parameters for different age groups were obtained using the regression method. The carcinogenic and non-carcinogenic risks of different population groups caused by arsenic exposure through different drinking water types were evaluated by a probabilistic risk assessment. The results showed that the geometric mean of total arsenic content in all the drinking water samples in China was (13.0±38.1) μg·L-1. The highest arsenic content was found in the Inner Mongolia Autonomous Region, followed by Guangxi and Shanxi. Based on the relevant standards for drinking water quality, the probability exceeding the threshold value of groundwater and source water is 23.2% and 18.4%, respectively. According to the results of non-carcinogenic risk assessment, the probability of the residents drinking well water and surface water from the water source area exceeding the daily average exposure dose threshold was 24.0% and 19.5%, respectively. According to the carcinogenic risk assessment, the median of carcinogenic risk caused by arsenic in drinking water in China was 3.22×10-5, which is acceptable. The population group of 18-45 years old had the highest risk, and the median LCR was 1.37×10-5. There was still a certain probability that the LCR of drinking well water and surface water would exceed the acceptable risk level recommended by the US EPA. In conclusion, the potential health risks caused by arsenic exposure through drinking water intake exist among Chinese residents. Further control of the arsenic concentration in drinking water is required to reduce the health risk and improve the safety of drinking water. Meanwhile, it is suggested to strengthen the research on risk threshold to provide a scientific basis for the residents' health protection.