Regional assessment of groundwater quality for drinking purpose

Owing to limited surface water during a long-term drought, this work attempted to locate clean and safe groundwater in the Choushui River alluvial fan of Taiwan based on drinking-water quality standards. Because aquifers contained several pollutants, multivariate indicator kriging (MVIK) was adopted to integrate the multiple pollutants in groundwater based on drinking- and raw-water quality standards and to explore spatial uncertainty. According to probabilities estimated by MVIK, safe zones were determined under four treatment conditions—no treatment; ammonium–N and iron removal; manganese and arsenic removal; and ammonium–N, iron, manganese, and arsenic removal. The analyzed results reveal that groundwater in the study area is not appropriate for drinking use without any treatments because of high ammonium–N, iron, manganese, and/or arsenic concentrations. After ammonium–N, iron, manganese, and arsenic removed, about 81.9–94.9% of total areas can extract safe groundwater for drinking. The proximal-fan, central mid-fan, southern mid-fan, and northern regions are the excellent locations to pump safe groundwater for drinking after treatment. Deep aquifers of exceeding 200 m depth have wider regions to obtain excellent groundwater than shallow aquifers do.     

Monitoring bacterial contamination of piped water supply in rural coastal Bangladesh

Safe drinking water is scarce in southwest coastal Bangladesh because of unavailability of fresh water. Given the high salinity of both groundwater and surface water in this area, harvested rainwater and rain-fed pond water became the main sources of drinking water. Both the government and non-government organizations have recently introduced pipe water supply in the rural coastal areas to ensure safe drinking water. We assessed the bacteriological quality of water at different points along the piped water distribution system (i.e., the source, treatment plant, household taps, street hydrants, and household storage containers) of Mongla municipality under Mongla Upazila in Bagerhat district. Water samples were collected at 2-month interval from May 2014 to March 2015. Median E. coli and total coliform counts at source, treatment plant, household taps, street hydrants, and household storage containers were respectively 225, 4, 7, 7, and 15 cfu/100 ml and 42,000, 545, 5000, 6150, and 18,800 cfu/100 ml. Concentrations of both of the indicator bacteria reduced after treatment, although it did not satisfy the WHO drinking water standards. However, re-contamination in distribution systems and household storage containers indicate improper maintenance of distribution system and lack of personal hygiene.     

Migration of Birds as an Indicator of Broad-Scale Environmental Condition

The general profile of the pollution of drinking water, originating from groundwater, by nitrates, chloride and arsenic, in the Prefecture of Thessaloniki, was studied in this project. Samples (tap water) were collected from 52 areas-villages of the Prefecture, during a period of 6 months. The analytical results were related to certain points on the map of the area, thus producing coloured representations of the Prefecture, according to the concentration of the corresponding pollutant. The statistical analysis of the data led to some conclusions concerning the causes of pollution and the relation of the concentrations to certain physico-chemical parameters. Nitrate concentration of samples collected from two specific regions were especially high, sometimes above the highest permitted level. A limited number of samples (13.5%) contained arsenic concentrations above the imminent EC drinking water limit (10 ppb). The majority of the tap water samples, collected from areas along the seashore contained increased concentrations of chloride ions, which is a clear indication of seawater intrusion into the related aquifers.     

Contaminated drinking water and rural health perspectives in Rajasthan, India: an overview of recent case studies

Access to safe drinking water is an important issue of health and development at national, regional, and local levels. The concept of safe drinking water assumes greater significance in countries like India where the majority of the population lives in villages with bare infrastructures and poor sanitation facilities. This review presents an overview of drinking water quality in rural habitations of northern Rajasthan, India. Although fluoride is an endemic problem to the groundwater of this region, recently, other anthropogenic chemicals has also been reported in the local groundwater. Recent case studies indicate that about 95% of sites of this region contain a higher fluoride level in groundwater than the maximum permissible limit as decided by the Bureau of Indian Standards. Nitrate (as NO $_{3}^{\,\,-})$ contamination has appeared as another anthropogenic threat to some intensively cultivable rural habitations of this region. Biological contamination has appeared as another issue of unsafe drinking water resources in rural areas of the state. Recent studies have claimed a wide variety of pathogenic bacteria including members of the family Enterobacteriaceae in local drinking water resources. Overall, the quality of drinking water in this area is not up to the safe level, and much work is still required to establish a safe drinking water supply program in this area.     

On the Environmental Efficiency of Water Storage: the Case of a Conjunctive use of Ground and Rainwater

Rainwater harvesting, consisting in collecting runoff from precipitation, has been widely developed to stop groundwater declines and even raise water tables. However, this expected environmental effect is not self-evident. We show in a simple setting that the success of this conjunctive use depends on whether the runoff rate is above a threshold value. Moreover, the bigger the storage capacity, the higher the runoff rate must be to obtain an environmentally efficient system. We also extend the model to include other hydrological parameters and ecological damages, which respectively increase and decrease the environmental efficiency of rainwater harvesting.     

Groundwater potential zoning of a peri-urban wetland of south Bengal Basin, India

Demand for groundwater for drinking, agricultural, and industrial purposes has increased due to rapid increase in population. Therefore, it is imperative to assess the groundwater potential of different areas, especially in a fragile wetland ecosystem to select appropriate sites for developing well fields to minimize adverse environmental impacts of groundwater development. This study considers East Calcutta Wetlands (ECW)??a freshwater peri-urban inland wetland ecosystem located at the lower part of the deltaic alluvial plain of South Bengal Basin and east of Kolkata city. This wetland is well known over the world for its resource recovery systems developed by local people through ages, using wastewater of the city. The subsurface geology is completely blanketed by the Quaternary sediments comprising a succession of silty clay, sand of various grades, and sand mixed with occasional gravels and thin intercalations of silty clay. Groundwater occurs mostly under confined condition except in those places where the top aquitard has been obliterated due to scouring action of past channels. The groundwater in the study area is being over-extracted at the rate of 65 × 10³ m³/day. Overlay analysis in Geographic Information System platform using multiple criteria such as water quality index, hydraulic conductivity, groundwater velocity, and depth to piezometric surface reveals that in and around ECW, there are five groundwater potential zones. About 74% of the aquifer of this area shows very poor to medium groundwater potential. Management options such as minimization of groundwater abstraction by introducing the treated surface water supply system and the implementation of rainwater harvesting and artificial recharge in high-rise buildings and industries are suggested for different potential zones.     

Evaluation of hydrochemical changes due to intensive aquifer exploitation: case studies from Mexico

The impact of intensive aquifer exploitation has been observed in numerous places around the world. Mexico is a representative example of this problem. In 2010, 101 out of the 653 aquifers recognized in the country, showed negative social, economic, and environmental effects related to intensive exploitation. The environmental effects include, among others, groundwater level decline, subsidence, attenuation, and drying up of springs, decreased river flow, and deterioration of water quality. This study aimed at determining the hydrochemical changes produced by intensive aquifer exploitation and highlighting water quality modifications, taking as example the Valle de Toluca, Salamanca, and San Luis Potosi aquifers in Mexico's highlands. There, elements such as fluoride, arsenic, iron, and manganese have been detected, resulting from the introduction of older groundwater with longer residence times and distinctive chemical composition (regional flows). High concentrations of other elements such as chloride, sulfate, nitrate, and vanadium, as well as pathogens, all related to anthropogenic pollution sources (wastewater infiltration, irrigation return flow, and atmospheric pollutants, among others) were also observed. Some of these elements (nitrate, fluoride, arsenic, iron, and manganese) have shown concentrations above Mexican and World Health Organization drinking water standards.     

Nitrate occurrence in the groundwater of the Loukkos perimeter

This study assesses the occurrence of nitrate in the groundwater beneath the R'mel area of the Loukkos perimeter (north-west Morocco), which covers an approximate area of 2,560 km2 and is located between the towns of Ksar el Kebir and Larache. It also borders the Atlantic Ocean. Groundwater supplies are the principal source of drinking water in this region and there is no public drinking water network in the rural area. This perimeter has a population of about 500,000 inhabitants of which the rural population represents 60%, many of whom have depended on and used the water from the aquifers for many years. The inhabitants and farmers depend on the groundwater supplies for drinking water, crop irrigation and other uses. The plain provides the ideal conditions for agriculture and the use of chemical fertilisers has been increasing. In this study, 53 water samples were collected from wells and springs. Each well or spring was sampled once or twice during 1998-2000. Nitrate concentrations ranged from extremely low up to 144 mg L(-1). Nitrate concentrations exceeded the maximum contaminant level (MCL) of 50 mg L(-1) in 12 of the 53 groundwater samples (23%), whereas 31 of the 53 samples (58%) had nitrate concentrations of less than 25 mg L(-1).     

Hydrogeological definition and applicability of abandoned coal mines as water reservoirs

Hydrogeologically, the Central Coal Basin (Asturias, Spain) is characterized by predominantly low-permeability materials that make up a multilayer aquifer with very low porosity and permeability values, where the sandstones act as limited aquifers, and wackes, mudstones, shales and coal seams act as confining levels. Preferential groundwater flow paths are open fractures and zones of decompression associated with them, so the hydraulic behaviour of the system is more associated with fracturing than lithology. Thus, abandoned and flooded mines in the area acquire an important role in the management of water resources, setting up an artificial "pseudo-karst" aquifer. This paper evaluates the potential application of the abandoned mines as underground reservoirs, both for water supply and energetic use, mainly through heat pumps and small hydropower plants. In particular, the groundwater reservoir shaped by the connected shafts Barredo and Figaredo has been chosen, and a detailed and multifaceted study has been undertaken in the area. The exposed applications fit with an integrated management of water resources and contribute to improve economic and social conditions of a traditional mining area in gradual decline due to the cessation of such activity.     

中国农村饮用水水源地水质状况研究

为了系统评估中国农村饮用水水源地水质变化情况，根据2009—2018年农村饮用水水源地水质监测数据，综合评价和分析了中国农村地表和地下饮用水达标情况、空间分布和主要超标因子等。监测结果表明：10年来，农村饮用水水源地达标率不断提高，这主要得益于地表饮用水水质整体改善；地下饮用水水质达标率持续偏低，且略有变差趋势，与城市地区的差距逐年加大。农村饮用水水源地超标断面和点位在空间上分布较广，主要超标因子相对集中，且表现出与农村和农业面源污染较强的相关性。建议进一步重视农村饮用水水源地（特别是地下饮用水）的保护，加强农村饮用水水源地水质监测，加快农业面源污染防治。     

Assessment of the school drinking water supply and the water quality in Pingtung County, Taiwan

In this study, a questionnaire survey of school drinking water quality of 42 schools in Pingtung County was conducted according to the water sources, treatment facilities, location of school as well as different grade levels. Among them, 45% of schools used tap water as the main source of drinking water, and the schools using groundwater and surface water as drinking water source account for 29% and 26%, respectively. The schools above senior high school level in the city used tap water as drinking water more than underground water, while the schools under junior high school level in the rural area used surface water as their main source of drinking water. The surface water was normally boiled before being provided to their students. The reverse osmosis system is a commonly used water treatment equipment for those schools using tap water or underground water. Drinking fountain or boiled water unit is widely installed in schools above senior high school level. For schools under junior high school level, a pipeline is stretched across the campus. Relative test shows that the unqualified rate of microbe in water is 26.2%. All parameters for physical and chemical properties and metal content had met the domestic standards except that the turbidity of schools under junior high school level using tap water is slightly higher than the standard value.     

Organochlorine pesticide residues in drinking water in the rural areas of Haryana,India

Drinking water samples collected from rural areas of three districts of Haryana during pre-monsoon and post-monsoon periods were analysed for the presence of organochlorine pesticide residues. The main source of drinking water in rural areas, i.e. groundwater in Ambala and Gurgaon districts and surface water supply in Hisar district, was found to be contaminated with isomers of HCH and endosulfan and metabolites of DDT, whereas dieldrin remained below detection limits. During the study period, the mean values observed for total HCH, DDT and endosulfan were 87.6, 848.2, and 27.4 ng/L and 99.8, 275.3 and 164.2 ng/L, respectively, for Ambala and Gurgaon districts. In the case of Hisar district, the values were 78.5, 115.9, and 53.0 ng/L, respectively. During the study period, 37% of the samples exceeded the total pesticide level of 500 ng/L indicated in the EECD directive for drinking water. Seasonal variations of pesticide residues were also observed during the study period.     

Groundwater arsenic contamination in Brahmaputra river basin: a water quality assessment in Golaghat (Assam), India

Distribution of arsenic (As) and its compound and related toxicology are serious concerns nowadays. Millions of individuals worldwide are suffering from arsenic toxic effect due to drinking of As-contaminated groundwater. The Bengal delta plain, which is formed by the Ganga?CPadma?CMeghna?CBrahmaputra river basin, covering several districts of West Bengal, India, and Bangladesh is considered as the worst As-affected alluvial basin. The present study was carried out to examine As contamination in the state of Assam, an adjoining region of the West Bengal and Bangladesh borders. Two hundred twenty-two groundwater samples were collected from shallow and deep tubewells of six blocks of Golaghat district (Assam). Along with total As, examination of concentration levels of other key parameters, viz., Fe, Mn, Ca, Na, K, and Mg with pH, total hardness, and SO $_{4}^{2-}$ , was also carried out. In respect to the permissible limit formulated by the World Health Organization (WHO; As 0.01 ppm, Fe 1.0 ppm, and Mn 0.3 ppm for potable water), the present study showed that out of the 222 groundwater samples, 67%, 76.4%, and 28.5% were found contaminated with higher metal contents (for total As, Fe, and Mn, respectively). The most badly affected area was the Gamariguri block, where 100% of the samples had As and Fe concentrations above the WHO drinking water guideline values. In this block, the highest As and Fe concentrations were recorded 0.128 and 5.9 ppm, respectively. Tubewell water of depth 180 ± 10 ft found to be more contaminated by As and Fe with 78% and 83% of the samples were tainted with higher concentration of such toxic metals, respectively. A strong significant correlation was observed between As and Fe (0.697 at p < 0.01), suggesting a possible reductive dissolution of As?CFe-bearing minerals for the mobilization of As in the groundwater of the region.     

Quality assessment of groundwater from the south-eastern Arabian Peninsula

Assessment of groundwater quality plays a significant role in the utilization of the scarce water resources globally and especially in arid regions. The increasing abstraction together with man-made contamination and seawater intrusion have strongly affected groundwater quality in the Arabia Peninsula, exemplified by the investigation given here from the United Arab Emirates, where the groundwater is seldom reviewed and assessed. In the aim of assessing current groundwater quality, we here present a comparison of chemical data linked to aquifers types. The results reveal that most of the investigated groundwater is not suitable for drinking, household, and agricultural purposes following the WHO permissible limits. Aquifer composition and climate have vital control on the water quality, with the carbonate aquifers contain the least potable water compared to the ophiolites and Quaternary clastics. Seawater intrusion along coastal regions has deteriorated the water quality and the phenomenon may become more intensive with future warming climate and rising sea level.     

Arsenic content in ground and canal waters of Punjab, North-West India

Groundwater is the primary source of drinking water for more than 95% of the population in Punjab. The world health organization and US Environment Protection Agency recently established a new maximum contaminant level of 10 ppb for arsenic in drinking water. The arsenic concentration of deep water tube wells located in Amritsar city used for domestic supply for urban population ranged from 3.8 to 19.1 ppb with mean value of 9.8 ppb. Arsenic content in hand pump water varied from 9 to 85 ppb with a mean value of 29.5 ppb. According to the safe limit of As, 54% and 97%, water samples collected from deep water tube wells and hand pumps, respectively, were not fit for human consumption. Arsenic content in canal water varied from 0.3 to 8.8 ppb with a mean value of 2.89 ppb. Canal water has got higher oxidation potential followed by deep tube well and hand pump water. The present study suggests the regular monitoring of arsenic content in deep tube well and shallow hand pump waters by water testing laboratories. The consumption of water having elevated concentration of As above the safe limit must be discouraged. In south-western districts of Punjab, it recommends the use of canal water for drinking purposes and domestic use by rural and urban populations than ground water sources.     

Pesticides and Nitrate in Groundwater and Rainwater in the Province of Limburg in The Netherlands

The purpose of this study was to investigate the occurrence ofhigh levels of pesticides in groundwater and rainwater in TheProvince of Limburg in The Netherlands. In groundwater samplesin particular the presence of triazines – atrazine, simazine and propazine – was observed; besides these pesticides, dieldrin has also been observed. Atrazine and simazine were found to exceed the groundwater standard of 100 ng L^-1. In the rainwater samples, the presence of 13 of 23 different analyzed pesticides was observed. A number of pesticides werefound in high concentrations; e.g. atrazine (>200 ng L^-1). Two pesticides detected in rainwater (+-HCH and atrazine) were found to exceed the groundwater standard. Seven pesticides in rainwater were found to exceed the target value and three pesticides the maximum tolerable risk value (DDT, heptachlor and heptachlorepoxide A), which are used as ecotoxicological standards in The Netherlands.Nitrate in 15 of 16 analyzed natural springs was found toexceed the guideline value for nitrate in drinking waterof 50 mg L^-1, up to levels of about 200 mg L^-1. Nitrate concentrations in rainwater samples were observed up to 4.5 mg L^-1. A risk analysis of exposure to high pesticide levels in groundwater or rainwater has been performed using the model HESP. For atrazine levels due todeposition of rainwater in two different locations, exceedance of the T.D.I. level of 0.5 g kg^-1 day^-1 based on WHO criteria was observed for children using both an urban and a rural scenario and use of groundwater as drinking water.     

Assessment of groundwater quality and <Superscript>222</Superscript>Rn distribution in the Xuzhou region,China

Evaluation of groundwater quality represents significant input for the development and utilization of water resources. Increasing exploitation of groundwater and man-made pollution has seriously affected the groundwater quality of the North China Plain, such as in the Xuzhou region which is the target of this investigation. The assessment of the groundwater quality and sources in the region was based on analyses of water chemistry and ²²²Rn activity in samples collected from wells penetrating unconfined and confined aquifers. The results indicate that most of the untreated groundwater in the region is not suitable for the long-term drinking based on permissible limits of the Chinese Environmental Agency and the World Health Organization. However, the groundwater can be used as healthy source of drinking water when they can pass the biological test and softening water treatment. Most of the groundwater is suitable for irrigation. Excessive amounts of SO₄^2? and NO₃^? are attributed to mainly influence of wastewater, irrigation, and dissolution of sulfate minerals in local coal strata. The major source of the groundwater is meteoric recharge with addition from irrigation and wastewater discharges. Variability of the water quality seems to be also reflecting the type of aquifers where the highest concentration of HCO₃^? occurs in water of the carbonate fractured aquifer, while the highest Cl^? concentration in the unconfined aquifer. Source of ²²²Rn activity is mainly related to the rock-water interaction with possible addition from the agricultural fertilizers. Protection of groundwater is vital to maintain sustainable drinking quality through reducing infiltration of irrigation water and wastewater.     

垃圾填埋场地下水污染对居民健康的风险评价

调查了某垃圾填埋场地下水和周边居民饮用水中的As、Hg等重金属和挥发酚等有机物的污染状况，运用美国环保局的健康风险计算模型，评估了该垃圾填埋场地下水对周边居民的潜在健康风险。结果表明，各类人群对4种有阈化合物的饮食和皮肤暴露的终身健康危险度在8．2×10^-11～1．3×10^-10之间，均低于可以接受的风险水平10^-6；对As的终身超额健康危险度在3．1×10^-7～4．9×10^-7之间，表明地下水中砷污染对居民潜在的致癌风险不明显。各类人群通过皮肤对Hg、As、Cd和挥发酚的暴露剂量比通过饮水暴露的剂量高0．7倍～14．5倍，皮肤暴露将是地下水影响人体健康并构成潜在风险的重要途径。     

Arsenic and Other Metal Contamination of Groundwaters in the Industrial Area of Thessaloniki, Northern Greece

In groundwater, used for drinking water supply in the greater industrial area of Thessaloniki, in Northern Greece, concentrations of total arsenic exceeded the WHO provisional guideline value and the EU maximum contaminant level (MCL) of 10 μg/L. The concentration of total arsenic was in the range between 4–130 μg/L, whereas the median value was 36 μg/L and the average concentration 46 μg/L. Nine out of the eleven wells contained total arsenic at concentration higher than 10 μg/L and it should be stressed that 6 of them contain arsenic at concentrations between 10 (new MCL) and 50 μg/L (previous MCL). The examined groundwaters were found to contain elevated concentrations of manganese and phosphate. Arsenic had a positive correlation with the pH, indicating the possible effect of pH on arsenic mobilisation. These findings emerge the problem of contamination from arsenic, since, according to the EU directive 98/83, all drinking water sources within the European Union should have achieved compliance with the new limits by 12/2003, implying that the situation requires urgent remedial action.     

Potential health risk of arsenic and cadmium in groundwater near Xiangjiang River, China: a case study for risk assessment and management of toxic substances

As part of our efforts to find effective methods to the drinking water risk management, the health risk assessment of arsenic and cadmium in groundwater near Xiangjiang River was analyzed. The results suggest that although the arsenic and cadmium concentrations in 97% of groundwater sources are less than the requirement of Water Quality Standards for Drinking Water (GB5749-2006) in China, the residents served by almost all of the investigated centralized drinking water sources have a significant potential health risk by consumption, especially cancer risk. It is justified through analyses that risk assessment is an effective tool for risk management, and the maximum permissible concentration of arsenic and cadmium in drinking water (0.01 and 0.005?mg L^-1, respectively) is suitable for China at present, considering the current economic status of China. Risk managers develop cleanup standards designed to protect against all possible adverse effects, which should take into account highly exposed individuals, effects of mixtures of toxic substances, attendant uncertainties, and other factors such as site-specific (or generic) criteria, technical feasibility, cost?Cbenefit analyses, and sociopolitical concerns.