Dey NC, Parvez M, Dey D, Saha R, Ghose L, Barua MK, Islam A, Chowdhury MR. Microbial contamination of drinking water from risky tubewells situated in different hydrological regions of Bangladesh. Int J Hyg Environ Health. 2016 Dec 29. pii: S1438-4639(16)30270-X. doi: 10.1016/j.ijheh.2016.12.007.
This study, conducted in 40 selected upazilas covering four hydrological regions of Bangladesh, aimed at determining the risk of selected shallow tubewells (depth<30m) used for drinking purpose (n=26,229). This was based on WHO’s sanitary inspection guidelines and identifying the association of sanitary inspection indicators and risk scores with microbiological contamination of shallow tubewells. The main objective of the study was to observe the seasonal and regional differences of microbial contamination and finally reaching a conclusion about safe distance between tubewells and latrines by comparing the contamination of two tubewell categories (category-1: distance ≤10m from nearest latrine; n=80 and category 2: distances 11-20m from nearest latrine; n=80) in different geographical contexts. About 62% of sampled tubewells were at medium to high risk according to WHO’s sanitary inspection guidelines, while the situation was worst in south-west region. Microbiological contamination was significantly higher in sampled category-1 tubewells compared to category-2 tubewells, while the number of contaminated tubewells and level of contamination was higher during wet season. About 21% (CI95=12%-30%), 54% (CI95=43%-65%) and 58% (CI95=46%-69%) of water samples collected from category-1 tubewells were contaminated by E. coli, FC, and TC respectively during the wet season. The number of category-1 tubewells having E.coli was highest in the north-west (n=8) and north-central (n=4) region during wet season and dry season respectively, while the level of E.coli contamination in tubewell water (number of CFU/100ml of sample) was significantly higher in north-central region. However, the south-west region had the highest number of FC contaminated category-1 tubewells (n=16 & n=17; respectively during wet and dry season) and significantly a higher level of TC and FC in sampled Category-1 tubewells than north-west, north-central and south-east region, mainly during wet season. Multivariate regression analysis could identified some sanitary inspection indicators, such as tubewell within <10m of latrine, platform absent/broken, pollution source (i.e. household’s waste dumping point/poultry/dairy farm) within 10m of tubewell and unimproved sanitation facility which were significantly associated with presence of microbial contaminants in tubewell water (p<0.01). A tubewell with high risk level was associated with a higher chance of having FC and TC in tubewell water than a tubewell with a medium risk during wet season, but no such conclusion could be drawn in case of E.coli contamination. Construction of pit latrine in areas with high water table should be highly discouraged. Raised sealed pits or flush/pour flash to septic tank could be installed considering sanitary inspection criteria. Water should be treated before drinking.
Kumar M, Das A, Das N, Goswami R, Singh UK. Co-occurrence perspective of arsenic and fluoride in the groundwater of Diphu, Assam, Northeastern India. Chemosphere 2016 Feb 19;150:227-238. doi: 10.1016/j.chemosphere.2016.02.019.
Considerable lacunae exists in As and F– co-contamination investigation in the Brahmaputra and Gangetic floodplains. Therefore we selected Diphu a township in the Karbi Plateau rising from the Brahmaputra floodplains for evaluation of As and F co-occurrence, correlation with coexisting ions of the aquifer system and elucidation of potential processes for releasing As and F– in the groundwater. Our initial appraisal used generic plots for identification of hydro geochemical processes and major water types. Subsequently, As and F– co-occurrence with pH, depth, HCO3–, SO42-, Ca2+ and Fe were probed for possible correlation followed by hierarchical cluster analyses to identify key processes for co-occurrence. Finally, saturation indices of groundwater minerals were calculated using MINTEQA2 to elucidate prospective As and F– release into groundwater. Results indicate F– and As presence in Ca-HCO3 rich water along with positive correlation between Ca2+ and F– possibly due to limestone reserves in adjoining areas. Multivariate analyses suggest the presence of high concentrations of PO43-, and H4SiO4 either individually or in combination can enhance the mobility of both As and F– and possibly abet conditions conducive for co-contamination of aquifers. Initial release of As and F– from the parent rock seems driven by the anthropogenic activities while mobilization depends on chemical interactions and individual affinities of the elements. The results of speciation highlight further mobilization of As and F– into the groundwater which in turn require regular attention for sustainable management of scarce water resource present in the area.
Kong XL, Wang SQ, Zhao H, Yuan RQ. [Distribution Characteristics and Source of Fluoride in Groundwater in Lower Plain Area of North China Plain: A Case Study in Nanpi County]. [Article in Chinese] [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui “Huan jing ke xue” bian ji wei yuan hui.].” 2015 Nov;36(11):4051-9.
There is an obvious regional contradiction between water resources and agricultural produce in lower plain area of North China, however, excessive fluorine in deep groundwater further limits the use of regional water resources. In order to understand the spatial distribution characteristics and source of F(-) in groundwater, study was carried out in Nanpi County by field survey and sampling, hydrogeochemical analysis and stable isotopes methods. The results showed that the center of low fluoride concentrations of shallow groundwater was located around reservoir of Dalang Lake, and centers of high fluoride concentrations were located in southeast and southwest of the study area. The region with high fluoride concentration was consistent with the over-exploitation region of deep groundwater. Point source pollution of subsurface drainage and non-point source of irrigation with deep groundwater in some regions were the main causes for the increasing F(-) concentrations of shallow groundwater in parts of the sampling sites. Rock deposition and hydrogeology conditions were the main causes for the high F(-) concentrations (1.00 mg x L(-1), threshold of drinking water quality standard in China) in deep groundwater. F(-) released from clay minerals into the water increased the F(-) concentrations in deep groundwater because of over-exploitation. With the increasing exploitation and utilization of brackish shallow groundwater and the compressing and restricting of deep groundwater exploitation, the water environment in the middle and east lower plain area of North China will undergo significant change, and it is important to identify the distribution and source of F(-) in surface water and groundwater for reasonable development and use of water resources in future.
Schaider LA, Ackerman JM, Rudel RA. Septic systems as sources of organic wastewater compounds in domestic drinking water wells in a shallow sand and gravel aquifer. The Science of the Total Environment. 2016 Jan 12. pii: S0048-9697(15)31235-3. doi: 10.1016/j.scitotenv.2015.12.081.
Domestic drinking water wells serve 44 million people in the US and are common globally. They are often located in areas served by onsite wastewater treatment systems, including septic systems, which can be sources of biological and chemical pollutants to groundwater. In this study we tested 20 domestic drinking water wells in a sand and gravel aquifer on Cape Cod, Massachusetts, USA, for 117 organic wastewater compounds (OWCs) and for inorganic markers of septic system impact. We detected 27 OWCs, including 12 pharmaceuticals, five per- and polyfluoroalkyl substances (PFASs), four organophosphate flame retardants, and an artificial sweetener (acesulfame). Maximum concentrations of several PFASs and pharmaceuticals were relatively high compared to public drinking water supplies in the US. The number of detected OWCs and total concentrations of pharmaceuticals and of PFASs were positively correlated with nitrate, boron, and acesulfame and negatively correlated with well depth. These wells were all located in areas served exclusively by onsite wastewater treatment systems, which are likely the main source of the OWCs in these wells, although landfill leachate may also be a source. Our results suggest that current regulations to protect domestic wells from pathogens in septic system discharges do not prevent OWCs from reaching domestic wells, and that nitrate, a commonly measured drinking water contaminant, is a useful screening tool for OWCs in domestic wells. Nitrate concentrations of 1 mg/L NO3-N, which are tenfold higher than local background and tenfold lower than the US federal drinking water standard, were associated with wastewater impacts from OWCs in this study.
Chuah CJ, Lye HR, Ziegler AD, Wood SH, Kongpun C, Rajchagool S. Fluoride: A naturally-occurring health hazard in drinking-water resources of Northern Thailand. The Science of the total environment. 2015 Dec 31;545-546:266-279. doi: 10.1016/j.scitotenv.2015.12.069.
In Northern Thailand, incidences of fluorosis resulting from the consumption of high-fluoride drinking-water have been documented. In this study, we mapped the high-fluoride endemic areas and described the relevant transport processes of fluoride in enriched waters in the provinces of Chiang Mai and Lamphun. Over one thousand surface and sub-surface water samples including a total of 995 collected from shallow (depth: ≤30m) and deep (>30m) wells were analysed from two unconnected high-fluoride endemic areas. At the Chiang Mai site, 31% of the shallow wells contained hazardous levels (≥1.5mg/L) of fluoride, compared with the 18% observed in the deep wells. However, at the Lamphun site, more deep wells (35%) contained water with at least 1.5mg/L fluoride compared with the shallow wells (7%). At the Chiang Mai site, the high-fluoride waters originate from a nearby geothermal field. Fluoride-rich geothermal waters are distributed across the area following natural hydrological pathways of surface and sub-surface water flow. At the Lamphun site, a well-defined, curvilinear high-fluoride anomalous zone, resembling that of the nearby conspicuous Mae Tha Fault, was identified. This similarity provides evidence of the existence of an unmapped, blind fault as well as its likely association to a geogenic source (biotite-granite) of fluoride related to the faulted zone. Excessive abstraction of ground water resources may also have affected the distribution and concentration of fluoride at both sites. The distribution of these high-fluoride waters is influenced by a myriad of complex natural and anthropogenic processes which thus created a challenge for the management of water resources for safe consumption in affected areas. The notion of clean and safe drinking water can be found in deeper aquifers is not necessarily true. Groundwater at any depth should always be tested before the construction of wells.
Ali J, Kazi TG, Baig JA, Afridi HI, Arain MS, Ullah N, Brahman KD, Arain SS, Panhwar AH. Evaluation of the fate of arsenic-contaminated groundwater at different aquifers of Thar coalfield Pakistan. Environmental Science and Pollution Research International. 2015 Aug 9.
In present study, the ground water at different aquifers was evaluated for physicochemical parameters, iron, total arsenic, total inorganic arsenic and arsenic species (arsenite and arsenate). The samples of groundwater were collected at different depths, first aquifer (AQ1) 50-60 m, second aquifer (AQ2) 100-120 m, and third aquifer (AQ3) 200-250 m of Thar coalfield, Pakistan. Total inorganic arsenic was determined by solid phase extraction using titanium dioxide as an adsorbent. The arsenite was determined by cloud point extraction using ammonium pyrrolidinedithiocarbamate as a chelating reagent, and resulted complex was extracted by Triton X-114. The resulted data of groundwater were reported in terms of basic statistical parameters, principal component, and cluster analysis. The resulted data indicated that physicochemical parameters of groundwater of different aquifers were exceeded the World Health Organization provisional guideline for drinking water except pH and SO4 2-. The positive correlation was observed between arsenic species and physicochemical parameters of groundwater except F– and K+, which might be caused by geochemical minerals. Results of cluster analysis indicated that groundwater samples of AQ1 was highly contaminated with arsenic species as compared to AQ2 and AQ3 (p > 0.05).
Palamuleni L, Akoth M. Physico-Chemical and Microbial Analysis of Selected Borehole Waterin Mahikeng, South Africa. International Journal of Environmental Research and Public Health. 2015 Jul 23;12(8):8619-30. doi: 10.3390/ijerph120808619.
Groundwater is generally considered a “safe source” of drinking water because it is abstracted with low microbial load with little need for treatment before drinking. However, groundwater resources are commonly vulnerable to pollution, which may degrade their quality. An assessment of microbial and physicochemical qualities of borehole water in the rural environs of Mahikeng town, South Africa, was carried out. The study aimed at determining levels of physicochemical (temperature, pH, turbidity and nitrate) and bacteriological (both faecal and total coliform bacteria) contaminants in drinking water using standard microbiology methods. Furthermore, identities of isolates were determined using the API 20E assay. Results were compared with World Health Organisation (WHO) and Department of Water Affairs (DWAF-SA) water quality drinking standards. All analyses for physicochemical parameters were within acceptable limits except for turbidity while microbial loads during spring were higher than the WHO and DWAF thresholds. The detection of Escherichia coli, Salmonella and Klebsiella species in borehole water that was intended for human consumption suggests that water from these sources may pose severe health risks to consumers and is unsuitable for direct human consumption without treatment. The study recommends mobilisation of onsite treatment interventions to protect the households from further possible consequences of using the water.