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1.
The objective of this study was to determine the bacterial contaminations in drinking water in Nyala city, South Darfur, Sudan with special reference to the internally displaced people camps (IDPs). Two hundred and forty water samples from different sites and sources including bore holes, hand pumps, dug wells, water points, water reservoir and household storage containers were collected in 2009. The most probable number method was used to detect and count the total coliform, faecal coliform and faecal enterococci. Results revealed that the three indicators bacteria were abundant in all sources except water points. Percentages of the three indicators bacteria count above the permissible limits for drinking water in all samples were 46.4% total coliform, 45.2% faecal coliform and 25.4% faecal enterococci whereas the highest count of the indicators bacteria observed was 1,600 U/100 ml water. Enteric bacteria isolated were Escherichia coli (22.5%), Enterococcus faecalis (20.42%), Klebsiella (15.00%), Citrobacter (2.1%) and Enterobacter (3.33%). The highest contamination of water sources was observed in household storage containers (20%) followed by boreholes (11.25%), reservoirs (6.24%), hand pumps (5.42%) and dug wells (2.49%). Contamination varied from season to season with the highest level in autumn (18.33%) followed by winter (13.75%) and summer (13.32%), respectively. All sources of water in IDP camps except water points were contaminated. Data suggested the importance of greater attention for household contamination, environmental sanitation control and the raise of awareness about water contamination.  相似文献   

2.
This study was primarily aimed at investigating the physicochemical and microbial quality of water in 14 such dugouts from five districts in the northern region of Ghana. Results obtained suggest that except for colour, turbidity, total iron and manganese, many physicochemical parameters were either within or close to the World Health Organisation’s acceptable limits for drinking water. Generally, colour ranged from 5 to 750 Hz (mean 175 Hz), turbidity from 0.65 to 568 nephelometric turbidity units (NTU; mean 87.9 NTU), total iron from 0.07 to 7.85 mg/L (mean 1.0 mg/L) and manganese from 0.03 to 1.59 mg/L (mean 0.50 mg/L). Coliform counts in water from all the dugouts in both wet and dry seasons were, however, above the recommended limits for drinking water. Total and faecal coliforms ranged from 125 to 68,000 colony forming units (cfu)/100 mL (mean 10,623 cfu/100 mL) and <?1 to 19,000 cfu/100 mL (mean 1,310 cfu /100 mL), respectively. The poor microbial quality, as indicated by the analytically significant presence of coliform bacteria in all samples of dugout water, strongly suggests susceptibility and exposure to waterborne diseases of, and consequent health implications on, the many people who continuously patronise these vital water resources throughout the year. In particular, more proactive sustainable water management options, such as introduction to communities of simple but cost-effective purification techniques for water drawn from dugouts for drinking purposes, education and information dissemination to the water users to ensure environmentally hygienic practices around dugouts, may be needed.  相似文献   

3.
To ascertain the quality of drinking water being supplied, water quality monitoring and surveillance was conducted in Gangtok city at various treatment stages, service reservoirs, distribution network, public standposts, and households. No significant change in raw water quality was observed on day-to-day basis. Residual chlorine was found in the range of nil to 0.2 mg/l in the sump water/finished water. Throughout the year (i.e., during summer, winter, and monsoon seasons), the total coliform and fecal coliform counts were ranged from nil to 7 CFU/100 ml and nil to 3 CFU/100 ml, respectively, in sump water of Selep and VIP complex water treatment plant; however, at consumer end, those were observed as nil to 210 CFU/100 ml and nil to 90 CFU/100 ml, respectively. These variations in bacterial counts among the different service reservoirs and consumer ends may be attributed to the general management practices for maintenance of service reservoirs and the possibility of enroute contamination. Evaluation of the raw water quality indicates that the water is suitable for drinking after conventional treatment followed by disinfection. The finished water quality meets the level of standards described as per Bureau of Indian Standard specifications (BIS:10500 1991) for potability in terms of its physicochemical characteristics.  相似文献   

4.
This study has investigated the common risks associated with the water quality changes from the source to the consumer households and the associated disease burden in the piped water supplies. Samples from the source to the household storage from Nagpur City were collected and analysed for heavy metals, nutrient and microbial parameters. Sanitary risks were identified at the households during the socio-economic and sanitary survey. The water quality deterioration was the most at household storage around 30.3 % indicating that measures need to be taken to safeguard the water quality at the consumer level. Then, 31.2 % of the samples collected from public standposts and handpumps were positive for faecal contamination which implies that it is the weaker sections of the society who suffer the consequences of drinking unsafe water the most. On the basis of the laboratory results, risk analysis by surveying the WTPs, point-of-use behaviour at households and sanitary status at different socio-economic strata, the Water Safety Plan for Nagpur City was structured. The aim was to ensure that safe and improved water is reached to the individual household.  相似文献   

5.
The distribution of fecal coliforms was investigated and determined in Izmir Bay from 1996 to 2005. Izmir Bay severely was polluted from industrial and domestic discharges during decades. In early 2000, a wastewater treatment plant began to treat domestic and industrial wastes. This plant treats the wastes about 80% capacity after 2001. The sampling periods cover before and after treatment plant. Assessment method for determining the number of fecal coliform has evolved membrane filtrations. Maximum surface fecal coliform concentration was 4.9 × 105 cfu 100 ml???1 in 1996–2000 period. Following the opening treatment system, fecal coliform density decreased 2.1 × 104 cfu 100 ml???1 during 2001–2005. A continuous improvement can be sustained in the water quality if direct inflow of untreated wastewater is prevented.  相似文献   

6.
An investigation has been carried out of molybdenum in drinking water from a selection of public supply sources and domestic taps across England and Wales. This was to assess concentrations in relation to the World Health Organization (WHO) health-based value for Mo in drinking water of 70 μg/l and the decision to remove the element from the list of formal guideline values. Samples of treated drinking water from 12 water supply works were monitored up to four times over an 18-month period, and 24 domestic taps were sampled from three of their supply areas. Significant (p?p?>?0.05) were detected. Tap water samples collected from three towns (North Wales, the English Midlands, and South East England) supplied uniquely by upland reservoir water, river water, and Chalk groundwater, respectively, also showed a remarkable uniformity in Mo concentrations at each location. Within each, the variability was very small between houses (old and new), between pre-flush and post-flush samples, and between the tap water and respective source water samples. The results indicate that water distribution pipework has a negligible effect on supplied tap water Mo concentrations. The findings contrast with those for Cu, Zn, Ni, Pb, and Cd, which showed significant differences (p?England and Wales.  相似文献   

7.
We assessed the incidence of faecal-indicator bacteria in Tyume River over a 12-month period between August 2010 and July 2011. Total coliforms, faecal coliforms and enterococci were determined by the membrane filtration method. Total coliforms were detected in counts ranging from 2.1?×?102 to 3.4?×?104?CFU/100 ml. Faecal coliform counts ranged from 1?×?102 to 1.6?×?104?CFU/100 ml while enterococci counts were in the range of 3.3?×?101 to 5.1?×?103?CFU/100 ml. Indicator bacteria counts increased from upstream to downstream sampling sites. Counts of indicator bacteria at all sites were significantly affected by seasonal changes. The bacteriological qualities of the river water were poor, exceeding the guideline of 200 CFU/100 ml and 33 CFU/100 ml for faecal coliforms and enterococci, respectively, for recreational water. Faecal coliform counts also exceeded the 1,000 CFU/100 ml guideline for water used in fresh produce irrigation. Microbial source tracking results showed that faecal pollution was predominantly of human origin during spring at all sampling sites. During other seasons, human faecal pollution was largely confined to midstream and downstream sampling sites. Generally, the presence of faecal-indicator bacteria in the river water samples suggests faecal pollution of this freshwater resource, raising the possibility of the presence of pathogenic microorganisms in the water and a threat to public health.  相似文献   

8.
Laboratory experiment was conducted to understand the persistence behavior of tetraconazole in three soils of West Bengal (alluvial, red lateritic, and coastal saline) and also in water maintained at three different pH (4.0, 7.0, and 9.2) conditions. Processed soil samples (100 g) were spiked at two treatment doses: 2.5 μg/g (T1) and 5.0 μg/g (T2). Double distilled buffered water (200 ml) was spiked at two treatment doses: 1.0 μg/ml (T1) and 2.00 μg/ml (T2). The tetraconazole dissipation followed first-order reaction kinetics and the residual half-life (T 1/2) values in soil were found to be in the range of 66.9–77.2 days for T1 and 73.4–86.0 days for T2. The persistence increased in the order red lateritic > new alluvial > coastal saline. Interestingly, the red lateritic soil exhibited the lowest pH (5.56) and organic carbon (0.52 %) content as compared to other two soils. However, the dissipation of tetraconazole in case of water was not pH dependant. The T 1/2 values in water were in the range of 94 to 125 days. The study indicated the persistent nature of tetraconazole in soil and water.  相似文献   

9.
The Songhua River is the third largest river in China and the primary source of drinking and irrigation water for northeastern China. The distribution of 16 priority polycyclic aromatic hydrocarbons (PAHs) in water [dissolved water (DW) and suspended particulate matter (SPM)], sediment, and soil in the river basin was investigated, and the associated risk of cancer from these PAHs was also assessed. The total concentration of PAHs ranged from 13.9 to 161 ng L?1 in DW, 9.21 to 83.1 ng L?1 in SPM, 20.5 to 632 ng g?1 dw (dry weight) in sediment, and from 30.1 to 870 ng g?1 dw in soil. The compositional pattern of PAHs indicated that three-ring PAHs were predominant in DW and SPM samples, while four-ring PAHs dominated in sediment and soil samples. The spatial distribution of PAHs revealed some site-specific sources along the river, with principal component analysis indicating that these were from pyrogenic sources (such as coal and biomass combustion, and vehicle emissions) and coke oven emission distinguished as the main source of PAHs in the Songhua River Basin. Based on the ingestion of PAH-contaminated drinking water from the Songhua River, cancer risk was quantitatively estimated by combining the Incremental Lifetime Cancer Risk assessment model and BaP-equivalent concentration for five age groups of people (adults, teenagers, children, toddlers, and infants). Overall, the results suggest that the estimated integrated lifetime cancer risk for all groups was in acceptable levels. This study is the first attempt to provide information on the cancer risk of PAHs in drinking water from the Songhua River.  相似文献   

10.
In 2010, a magnitude 7.0 earthquake struck Haiti, severely damaging the drinking and wastewater infrastructure and leaving millions homeless. Compounding this problem, the introduction of Vibrio cholerae resulted in a massive cholera outbreak that infected over 700,000 people and threatened the safety of Haiti’s drinking water. To mitigate this public health crisis, non-government organizations installed thousands of wells to provide communities with safe drinking water. However, despite increased access, Haiti currently lacks the monitoring capacity to assure the microbial safety of any of its water resources. For these reasons, this study was designed to assess the feasibility of using a simple, low-cost method to detect indicators of fecal contamination of drinking water that could be implemented at the community level. Water samples from 358 sources of drinking water in the Léogâne flood basin were screened with a commercially available hydrogen sulfide test and a standard membrane method for the enumeration of thermotolerant coliforms. When compared with the gold standard method, the hydrogen sulfide test had a sensitivity of 65 % and a specificity of 93 %. While the sensitivity of the assay increased at higher fecal coliform concentrations, it never exceeded 88 %, even with fecal coliform concentrations greater than 100 colony-forming units per 100 ml. While its simplicity makes the hydrogen sulfide test attractive for assessing water quality in low-resource settings, the low sensitivity raises concerns about its use as the sole indicator of the presence or absence of fecal coliforms in individual or community water sources.  相似文献   

11.
Exposure to arsenic in arsenic endemic areas is most remarkable environmental health challenges. Although effects of arsenic contamination are well established, reports are unavailable on probable seasonal variation due to changes of food habit depending on winter and summer seasons, especially for endemic regions of Nadia district, West Bengal. Complete 24-h diets, drinking–cooking water, first morning voided urine samples, and diet history were analyzed on 25 volunteers in arsenic endemic Chakdah block of Nadia district, once in summer followed by once in winter from the same participants. Results depicted no seasonal variation of body weight and body mass index. Arsenic concentration of source drinking and cooking water decreased (p?=?0.04) from 26 μg L?1 in summer to 6 μg L?1 in winter season. We recorded a seasonal decrease of water intake in male (3.8 and 2.5 L day ?1) and female (2.6 and 1.2 L day?1) participants from summer to winter. Arsenic intake through drinking water decreased (p?=?0.04) in winter (29 μg day?1) than in summer (100 μg day?1), and urinary arsenic concentration decreased (p?=?0.018) in winter (41 μg L?1) than in summer (69 μg L?1). Dietary arsenic intake remained unchanged (p?=?0.24) over the seasons. Hence, we can infer that human health risk assessment from arsenic needs an insight over temporal scale.  相似文献   

12.
对2007-2013年乌鲁木齐市集中式饮用水源地水质监测数据进行综合分析,泉水型地下饮用水源地米东区三水厂受储水介质及当地地质化学结构的影响,溶解盐类常年超标,水质较差;湖库型地表水源地五、八水厂总磷浓度在个别年份存在一定程度的超标现象,且地表水源地中挥发性卤代烃类、硝基苯和酞酸酯类等有机项目及镍等重金属类检出率较高,存在一定程度的风险。对此提出了进一步完善水源地环境保护及合理开发优质水资源的对策建议,为首府饮用水源地的保护和相关研究工作提供依据。  相似文献   

13.
Safety of patients and dental personnel requires the appropriate microbiological water quality in dental units. During treatment, patients and dental workers are exposed both to direct contact with bacteria-contaminated water in the form of splatter and with contaminated water aerosol emitted during work by unit handpieces, including rotating and ultrasonic instruments. The aim of the study was to determine the qualitative and quantitative contamination of water in dental unit reservoirs with aerobic and facultative anaerobic bacteria. The study material included water sampled from 107 dental unit reservoirs located in dental surgeries of public health centres. Conventional microbiological methods were used to identify microorganisms. The study shows that the contamination of water in dental unit reservoirs with aerobic and facultative anaerobic bacteria is commonplace. The mean concentration of mesophile bacteria in dental unit reservoir water exceeded 1.1?×?105 cfu/ml. The prevailing species were Gram-negative bacteria of the families Burkholderiaceae, Pseudomonadaceae, Ralstoniaceae and Sphingomonadaceae. The most numerous bacteria were Ralstonia pickettii, constituting 49.33 % of all the identified aerobic and facultative anaerobic bacteria. Among Gram-positive rods, the most numerous were bacteria of the genus Brevibacterium (5.83 %), while the highest percentage shares (13.25 %) of all Gram-positive microorganisms were found for Actinomyces spp. The study confirms the necessity of regular monitoring of microbial contamination of dental unit waterlines (DUWL) and use of various water treatment procedures available to disinfect DWUL.  相似文献   

14.
Water quality and bacterial contamination from 18 drinking water municipal plants in three locations at Giza governorate were investigated. The average total count of bacteria detected after four stages of treatments in the investigated plants was 32 CFU/1 mL compared to 2330 cfu/mL for raw water, with a reduction percentage of 98.6. Although there is a relatively high removal percent of bacterial contamination from the water sources, however, several bacterial pathogens were identified in the produced water prepared for drinking including Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Shigella spp. After 3 days of water incubation at 30 °C, the amount of bacterial endotoxins ranged from 77 to 137 ng/mL in the water produced from the municipal plants compared to 621–1260 ng/mL for untreated water. The main diseases reported from patients attending different clinics and hospitals during summer 2014 at the surveyed locations and assuredly due to drinking water from these plants indicated that diarrheas and gastroenteritis due to E. coli and Campylobacter jejuni constituted 65.7% of the total patients followed by bacillary dysentery or shigellosis due to Shigella spp. (7.9%) and cholera due to Vibrio cholera (7.2%). There was an increase in serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) as well as urea and creatinine values of guinea pigs consuming water produced from the non-governmental plants for 6 months indicating remarkable liver and kidney damages. Histological sections of liver and kidney from the tested animal revealed liver having ballooning degeneration of hepatocytes and distortion and fragmentation of the nuclei, while the section of the kidney showed irregularly distributed wrinkled cells, degenerated Bowman’s capsule, congested blood vessels, and inflammatory cells.  相似文献   

15.
The spatial variation of chlorophyll a (Chl a) and factors influencing the high Chl a were studied during austral summer based on the physical and biogeochemical parameters collected near the coastal waters of Antarctica in 2010 and a zonal section along 60°S in 2011. In the coastal waters, high Chl a (>3 mg m?3) was observed near the upper layers (~15 m) between 53°30′E and 54°30′E. A comparatively higher mesozooplankton biomass (53.33 ml 100 m?3) was also observed concordant with the elevated Chl a. Low saline water formed by melting of glacial ice and snow, as well as deep mixed-layer depth (60 m) due to strong wind (>11 ms?1) could be the dominant factors for this biological response. In the open ocean, moderately high surface Chl a was observed (>0.6 mg m?3) between 47°E and 50°E along with a Deep Chlorophyll Maximum of ~1 mg m?3 present at 30–40 m depth. Melt water advected from the Antarctic continent could be the prime reason for this high Chl a. The mesozooplankton biomass (22.76 ml 100 m?3) observed in the open ocean was comparatively lower than that in the coastal waters. Physical factors such as melting, advection of melt water from Antarctic continent, water masses and wind-induced vertical mixing may be the possible reasons that led to the increase in phytoplankton biomass (Chl a).  相似文献   

16.
Probability-based nitrate contamination map of groundwater in Kinmen   总被引:1,自引:0,他引:1  
Groundwater supplies over 50 % of drinking water in Kinmen. Approximately 16.8 % of groundwater samples in Kinmen exceed the drinking water quality standard (DWQS) of NO3 ?-N (10 mg/L). The residents drinking high nitrate-polluted groundwater pose a potential risk to health. To formulate effective water quality management plan and assure a safe drinking water in Kinmen, the detailed spatial distribution of nitrate–N in groundwater is a prerequisite. The aim of this study is to develop an efficient scheme for evaluating spatial distribution of nitrate–N in residential well water using logistic regression (LR) model. A probability-based nitrate–N contamination map in Kinmen is constructed. The LR model predicted the binary occurrence probability of groundwater nitrate–N concentrations exceeding DWQS by simple measurement variables as independent variables, including sampling season, soil type, water table depth, pH, EC, DO, and Eh. The analyzed results reveal that three statistically significant explanatory variables, soil type, pH, and EC, are selected for the forward stepwise LR analysis. The total ratio of correct classification reaches 92.7 %. The highest probability of nitrate–N contamination map presents in the central zone, indicating that groundwater in the central zone should not be used for drinking purposes. Furthermore, a handy EC–pH-probability curve of nitrate–N exceeding the threshold of DWQS was developed. This curve can be used for preliminary screening of nitrate–N contamination in Kinmen groundwater. This study recommended that the local agency should implement the best management practice strategies to control nonpoint nitrogen sources and carry out a systematic monitoring of groundwater quality in residential wells of the high nitrate–N contamination zones.  相似文献   

17.
To evaluate boron contamination of public drinking water in China, both dissolved and total boron contents in 98 public drinking water sources from 49 cities, 42 brands of bottled water samples from supermarkets in several cities, and 58 water samples from boron industrial area were measured by inductively coupled plasma-mass spectrometry (ICP-MS). Our experimental results showed that boron existed in public drinking water sources mainly in dissolved status with total concentrations ranging from 0.003 to 0.337 mg/L (mean = 0.046 mg/L). The mean boron concentrations in mineral and pure bottled water were 0.052 and 0.028 mg/L, respectively. The results obtained in this work showed that there was no health risk on view of boron in public drinking water sources and bottled water. In boron industrial area, boron concentrations in surface water and ground water were 1.28 mg/L (range = 0.007–3.8 mg/L) and 18.3 mg/L (range = 0.015–140 mg/L), respectively, which indicated that boron industry caused boron pollution in local water system.  相似文献   

18.
There is considerable interest in minimizing the chlorine residual in Japan because of increasing complaints about a chlorinous odor in drinking water. However, minimizing the chlorine residual causes the microbiological water quality to deteriorate, and stricter control of biodegradable organics in finished water is thus needed to maintain biological stability during water distribution. In this investigation, an acceptable level of assimilable organic carbon (AOC) for biologically stable water with minimized chlorine residual was determined based on the relationship between AOC, the chlorine residual, and bacterial regrowth. In order to prepare water samples containing lower AOC, the fractions of AOC and biodegradable organic matter (BOM) in tap water samples were reduced by converting into biomass after thermal hydrolysis of BOM at alkaline conditions. The batch-mode incubations at different conditions of AOC and chlorine residual were carried out at 20°C, and the presence or absence of bacterial regrowth was determined. The determined curve for biologically stable water indicated that the acceptable AOC was 10.9 μg C/L at a minimized chlorine residual (0.05 mg Cl2/L). This result indicated that AOC removal during current water treatment processes in Japan should be significantly enhanced prior to minimization of the chlorine residual in water distribution.  相似文献   

19.
Accurate measurement of bacterial and viral abundance in coastal marine environments is important to understand the dynamics of microbial communities in these ecosystems. In this study, the effect of formaldehyde preservation on the abundance of bacteria and viruses in water samples from Cochin Backwater was determined by SYBR Green I staining and epifluorescence microscopy. The counts were determined for 45 days in samples fixed with 1?C6% formaldehyde. The results suggest rapid decline in counts of bacteria and viruses in samples preserved in formaldehyde, and the decline increased with increase in the final concentration of formaldehyde in the sample. The initial bacterial and viral counts in the sampling site were 5.2 × 106/ml and 3.9 × 107/ml, respectively. The bacterial count dropped by 5.1%, 53.3%, 55.7%, and 85% after 1, 7, 15, and 45 days, respectively, in sample fixed with 1% formaldehyde. The decline in viral counts was higher, being 32.4%, 47.9%, 68.1%, and 93% after 1, 7, 15, and 45 days, respectively. Storage of fixed samples at ??20°C did not halt the decline in microbial counts, suggesting that, irrespective of storage temperature, formaldehyde-fixed samples lead to underestimation of microbial counts.  相似文献   

20.
The present study was conducted to investigate drinking water quality (groundwater) from water samples taken from Qasim Abad, a locality of approximately 5,000 population, situated between twin cities Rawalpindi and Islamabad in Pakistan. The main sources of drinking water in this area are water bores which are dug upto the depth of 250–280 ft in almost every house. The study consists of the determination of physico-chemical properties, trace metals, heavy metals, rare earth elements and microbiological quality of drinking water. The data showed the variation of the investigated parameters in samples as follows: pH 6.75 to 8.70, electrical conductivity 540 to 855 μS/cm, total dissolved solids 325.46 to 515.23 ppm and dissolved oxygen 1.50 to 5.64 mg/L which are within the WHO guidelines for drinking water quality. The water samples were analysed for 30 elements (aluminium, iron, magnesium, manganese, silicon, zinc, molybdenum, titanium, chromium, nickel, tungsten, silver, arsenic, boron, barium, beryllium, cadmium, cobalt, copper, gallium, mercury, lanthanum, niobium, neodymium, lead, selenium, samarium, tin, vanadium and zirconium) by using inductively coupled plasma atomic emission spectroscopy. The organic contamination was detected in terms of most probable number (MPN) of faecal coliforms. Overall, elemental levels were lower than the recommended values but three water bores (B-1, B-6, B-7) had higher values of iron (1.6, 2.206, 0.65 ppm), two water bores (B-1, B-6) had higher values of aluminium (0.95, 1.92 ppm), respectively, and molybdenum was higher by 0.01 ppm only in one water bore (B-11). The total number of coliforms present in water samples was found to be within the prescribed limit of the WHO except for 5 out of 11 bore water samples (B-2, B-3, B-4, B-8, B-11), which were found in the range 5–35 MPN/100 mL, a consequence of infiltration of contaminated water (sewage) through cross connection, leakage points and back siphoning.  相似文献   

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