Efficiency of Modified H2S Test for Detection of Faecal Contamination in Water

Faecal contamination is a major causative factor for incidence of water borne infectious diseases. Certain hydrogen sulfide (H₂S) producing enteric bacteria such as Salmonella sp. and Citrobacter sp., assosiated with coliforms, have been considered for rapid detection of recent faecal contamination in water. The basic H₂S test medium, modified by adding 0.25 gm/L of L-cystine HCl, was examined for its efficiency with 90 water samples collected from 40 pipe supplies, 20 open wells, 15 hand pumps and 15 different surface water bodies (river, streams and ponds). Sterilized modified culture medium in glass vials was inoculated with 100 mL of each sample and incubated at 20, 25, 30, 35 and 44 ^∘C for 18, 24, 42, 48, 66 and 72 h. Blackening of content in incubated vials was considered positive. For comparison, most probable number (MPN) of coliform and faecal coliform per 100 mL was also estimated in each sample by multiple tube fermentation (MTF) method. H₂S positive result was exhibited by 78% of samples. Coliform (> 10) and faecal coliform/100 mL were also detected in 59% of samples. Maximum H₂S positive results (100%) were found with well and surface water samples incubated at 30, 35 and 44 ^∘C for 18 h. Coliform (> 10) and faecal coliform/100 mL were also detected in most of these samples. Pipe supplies (60%) and hand pumps (73%) also exhibited considerable H₂S production. Coliforms and faecal coliforms were also found in significant number of these samples. Thus, the modified H₂S test may prove a useful alternative indicator of faecal contamination for water quality surveillance and screening of large number of water samples in short duration, particularly during any outbreak of water borne disease among rural population.     

The water quality of the Vrgorska Matica River

The article presents the results of investigations carried out on the 42 km long Vrgorska Matica River, which flows through the 15 km long Vrgorsko polje (polje = field) which covers an areaof 3000 ha, and is at 24 m a.s.l., located in Southern Croatia.It covers the years 1997–2000 after this field had been reclaimed for agricultural use.The purpose of the investigations was to evaluate the influence of the Vrgorska Matica River which is part of the catchment areaof the Trebizat River, on the water quality in Modro Oko Lakeand Prud Spring, which are used for water supply and are locateddownstream of the Vrgorska Matica River on the right bank of theNeretva River.The water quality was evaluated by using the quality index basedon the following nine parameters: temperature, mineralization, corrosion coefficient, K = (Cl + SO₄)/HCO₃, dissolvedoxygen, BOD₅, total N, protein N, total phosphorus and totalcoliform bacteria (100 mL)^-1 (MPN coli (100 mL)^-1) for which concentrations C ₉₅ are calculated. After completingthe nine parameters the results of C ₉₅ were recorded andtransferred to the score table to obtain the q-value. The q-value used is an attempt to quantify environmental factors which would otherwise be qualitative. For each parameter the q-value was multiplied by a weighting factor based upon the relative significance of the parameter. The nine resulting scores values were then added to arrive at an overall water quality index (S₉₅).According to this index the water can be classified into four categories. The first category, according to the Croatian Water Classification Act (Official Bulletin No. 77,1998), includes ground and surface waters used for drinking or in the food industry either in its natural state or after disinfection, and surface water used for raising high-quality species of fish, ranging from 85–100 scores; the second category includes waterused in its natural state for swimming and recreation, sports orfor other species of fish and the treated water used for drinkingand other industrial purposes ranging between 70–85 scores. Thethird category includes water used in industry with no specific requests upon water quality and in agriculture ranging from 50–70 scores; the fourth category includes water used only afterbeing treated in areas with water shortage which is less than 50 scores.According to results obtained by investigations, the water of theVrgorska Matica River and Prud Spring falls into the second (II)category, while water from the Modro Oko Lake belongs to the first (I) category. This means that the Matica River water does not influence the water quality of the Modro Oko Lake. This lakewater quality is influenced by the Rastoka Matica River from theRastoko polje which is located upstream from the Vrgorska MaticaRiver. This has been proved by dyeing tests.     

Water quality assessment: surface water sources used for drinking and irrigation in Zaria,Nigeria are a public health hazard

We assessed the quality and pollution status of source surface waters in Zaria, Nigeria by monitoring the nature, cause and extent of pollution in Samaru stream, Kubanni River and Kubanni dam over a period of 10 months, between March and December 2002. A total of 228 water samples was collected from 12 sites and analysed for a total of ten physicochemical and one bacteriological quality indicators, using standard methods. Aesthetic water quality impairment parameters were also observed. The mean values of most water quality parameters were significantly higher (P < 0.05) in both the stream and river than in the dam. There was no significant correlation between faecal coliform counts (FCC) and water temperature (in the range 15–33°C); pH (5.77–7.32); and turbidity (1.4–567 NTU). The high FCC ranged from 2.0 × 10¹ to 1.6 × 10⁶ MPN/100 ml and exceeded the WHO standards for drinking water and water used for fresh-produce irrigation, and correlated positively (P < 0.05) with conductivity (in the range 68–1,029 μS/cm); TDS (10.0–70.0 mg/l); TSS (10.0–70.0 mg/l); Cl (7.5–181 mg/l); PO₄⁻P (0.01–0.41 mg/l); NO₃⁻N (0.6–3.8 mg/l) and BOD₅ (0.1–14.9 mg/l). The main pollution sources were municipal wastewater, stormwater runoffs, the ABU sewage treatment plant, abattoir effluents and irrigation farms treated with chemical fertilisers. We conclude that these water bodies are potentially hazardous to public health and that proper sewage treatment and river quality monitoring are needed to warn against hazards to public health.     

北京市典型重污染过程中PM2.5载带水溶性无机离子污染特征分析

为研究北京地区冬季PM_(2.5)载带的水溶性无机离子组分污染特征,2013年1月在中国环境科学研究院内采用在线离子色谱(URG-9000B,AIM-IC)对PM_(2.5)中水溶性无机离子(SO_4~(2-)、NO_3~-、Cl~-、NH_4~+、Na~+、K~+、Mg~(2+)、Ca~(2+))进行监测与分析。结果表明,采样期间总水溶性无机离子(TWSI)浓度为61.0μg/m~3,其中二次无机离子SO_4~(2-)、NO_3~-、NH_4~+(SNA)占比达72.3%,在PM_(2.5)中占比为40.29%,表明北京市PM_(2.5)二次污染严重。重污染天[NO_3~-]/[SO_4~(2-)]表明,固定源污染较移动源更为显著。三元相图表明,在空气质量为优的情况下,NH_4~+(在SNA中占比为30.3%~65.5%,下同)主要以NH_4NO_3的形式存在,较少比例以(NH_4)_2SO_4存在;严重污染时,NH_4~+(47.3%~77.9%)主要以(NH_4)_2SO_4形式存在,其次以NH_4NO_3的形式存在,其余的NH_4~+以NH_4Cl的形式存在。[NO_3~-]/[SO_4~(2-)]日变化表明,早、晚机动车高峰影响北京重污染发生。     

Chemical Composition of Bottled Water in Saudi Arabia

Fourteen domestic and seven imported bottled water brands were analysed in Saudi Arabia for various physico-chemical water quality parameters. The results of the analysis were compared with the drinking water standards set by Saudi Arabia and World Health Organization. The levels of different physico-chemical parameters like TDS, Ca, Mg, Na, K, NO₃, Cl and SO₄ of all local and imported bottled water brands met the different drinking water standards. Fluoride was found below the Saudi Arabian Standard Organization recommended limits in two of the local brands whereas fluoride levels in all of the imported brands were below the recommended values. In one imported brand, pH was found not conforming to the recommended standards. The concentrations of trace metals in all brands were within the drinking water standards. Comparison of the study results with the reported label values indicated good agreement with stated pH values but considerable variation for Ca, Mg, and Na in the local brands and comparatively low variation in the imported brands. Low F and SO₄ variations were found in the local brands and comparatively high SO₄ variation in the imported brands.     

Chlorination and water quality monitoring within a public drinking water supply in Rawalpindi Cantt (Westridge and Tench) area, Pakistan

Concern over the presence of fecal coliform in public drinking water supplies has been expressed in recent years in Pakistan since it has been regarded as pathogenic organism of prime importance in gastroenteritis. Two major drinking water distribution systems in the Cantt area of Rawalpindi district covering the Westridge and Tench areas was monitored over a 2-month period to determine the prevalence of fecal coliform and chlorine residual. The collected samples were examined for total chlorine, free chlorine residual, chloramines, total coliforms, fecal coliforms, and turbidity. The drinking water quality monitoring in the distribution network was performed by collecting samples from water source, overhead reservoir, and residential taps. In the Westridge area, total chlorine varied from the lowest value of 0.27 mg/L at Station # W-5 to the highest value of 0.42 mg/L at Station # W-2, total coliforms varied from 1.1 to 3.6 most probable number (MPN)/100 mL with presence of Escherichia coli in all samples, total dissolved solids (TDS) ranged from 199.5 to 205 mg/L, conductivity fluctuated between 399 and 411 microS/cm, and turbidity varied from 0.43 to 0.73 NTU. In the Tench area, the value of total chlorine ranged from 0.14 mg/L at Station # T-7 to 0.55 mg/L at Station # T-1. Total coliform varied from 3.6 to 5.1 MPN/100 mL and fecal coliform were detected at all the stations except at Station # T-1. TDS ranged from 201.4 to 257 mg/L, conductivity varied from 343 to 513 microS/cm, and turbidity ranged between 0.66 and 1.55 NTU. It is recommended to the respective agencies to ensure that the chlorine residual is available at consumer end.     

Monitoring E. coli and total coliforms in natural spring water as related to recreational mountain areas

Natural spring water has unique properties, as it is rich in minerals that are considered to be beneficial to human health. A survey of the microbiological quality of natural spring water was conducted to assess possible risks from the consumption of the water by visitors in recreational mountain areas located in Seoul, South Korea. The densities of total coliforms and Escherichia coli were measured during the spring and the summer of 2002 to investigate the presence of coliform bacteria in the drinking spring waters. Total coliforms were detected in all samples and the mean density of total coliforms was up to a maximum of 228 CFU/mL. Detectable E. coli was found in 78% of all samples and the mean densities of E. coli varied from a minimum of 0 CFU/mL to a maximum of 15 CFU/mL in all samples. Malfunctioning septic systems and wildlife population appear to be the main source of E. coli contamination. Presence of E. coli in natural spring water indicates potential adverse health effects for individuals or populations exposed to this water. The fecal contaminated spring water may present an unacceptable risk to humans if it is used as raw drinking water.     

Environmental pollutions impacts on the bacteriological and physicochemical quality of suburban and rural groundwater supplies in Marrakesh area (Morocco)

This study scrutinized bacteriological and chemical quality of groundwater supplies of Marrakesh (Morocco) within a year. It assessed the influence of some chemical factors on fecal and opportunistic pathogenic bacterial communities. The annual average densities of fecal coliforms, fecal streptococci and Pseudomonas aeruginosa were respectively: 1891 colony forming units (CFU)/100 mL, 1246 CFU/100 mL and 206 CFU/100 mL. The total occurrence of these bacteria during the period of study was 94%. Detectable non-O1 Vibrio cholerae was present in 81% of samples and the mean abundances ranged from 0 to 11100 MPN/100 mL. Significant correlations between fecal coliforms and streptococci and between fecal coliforms and non-O1 V. cholerae (p < 0.01) were found. Fecal coliforms can be used to detect the presence of non-O1 V. cholerae in this groundwater. These well waters were greatly mineralized, hard, salt with high concentrations of nitrogenous ions and major elements (Ca(2+), Na(+), Cl(-), SO(2-)(4) and K(+)). Most of chemical parameters were relatively steady with time except for calcium, ammonium, nitrites and organic matter which were seasonally influenced. The degree of correlation between chemical parameters and the abundances of isolated bacteria is heterogeneous. The concentrations of calcium and nitrites favored (p < 0.01) the abundance of fecal coliforms and streptococci, but reduced P. aeruginosa abundances. Calcium, salinity, chlorides, nitrites and nitrates tests can be used for screening in situ when the laboratory facilities are limited. This work is expected to assist local authorities in developing plans and actions to reduce the pollution to acceptable levels.     

Major ion chemistry and weathering processes in the Midyan Basin, northwestern Saudi Arabia

Chemical characteristics of 72 groundwater samples collected from Midyan Basin have been studied to evaluate major ion chemistry together with the geochemical and weathering processes controlling the water composition. Water chemistry of the study area is mainly dominated by Na, Ca, SO₄, and Cl. The molar ratios of (Ca?+?Mg)/total cations, (Na?+?K)/total cations, (Ca?+?Mg)/(Na?+?K), (Ca?+?Mg)/(HCO₃?+?SO₄), (Ca?+?Mg)/HCO₃, and Na/Cl reveal that water chemistry of the Midyan Basin is controlled by evaporite dissolution (gypsum and/or anhydrite, and halite), silicate weathering, and minor contribution of carbonate weathering. The studied groundwater samples are largely undersaturated with respect to dolomite, gypsum, and anhydrite. These waters are capable of dissolving more of these minerals under suitable physicochemical conditions.     

A Comparison of Bacterial Indicators and Methods in Rural Surface Waters

The United States Environmental Protection Agency (USEPA) recommends the use of Escherichia coli (E. coli) and enterococci as indicators of enteric pathogens in fresh waters; however, fecal coliform analyses will remain important by virtue of the large amount of historic data collected in prior years. In this study, we attempted, in a real-world situation (i.e., a rural inland watershed in the Piedmont of South Carolina) to compare different bacterial indicators and methods to one another. We compared fecal coliforms, enumerated by membrane filtration with E. coli, enumerated by a commercialized enzyme substrate method and observed E. coli/fecal coliform ratios of 1.63 and 1.2 for two separate tests. In the same watershed, we observed an E. coli/fecal coliform ratio of 0.84 when we used the commercialized enzyme substrate method for both enumerations. Given these results, users of such data should exercise care when they make comparisons between historic membrane filtration data and data acquired through the use of the more modern enzymatic methods. Some sampling and side-by-side testing between methods in a specific watershed may be prudent before any conversion factors between old and new datasets are applied.