Spatial variability of shallow groundwater level, electrical conductivity and nitrate concentration, and risk assessment of nitrate contamination in North China Plain

In recent years, nitrate (NO3) contamination of groundwater has become a growing concern for people in rural areas in North China Plain (NCP) where groundwater is used as drinking water. The objective of this study was to evaluate groundwater resource level, to determine groundwater quality and to assess the risk of NO3 pollution in groundwater in Quzhou County in the NCP. Ordinary Kriging (OK) method was used to analyze the spatial variability of shallow groundwater level, groundwater electrical conductivity (EC) and NO3-N concentrations, and Indictor Kriging (IK) method was used to analyze the data with NO3-N concentrations equal or greater than the groundwater NO3 pollution threshold (20 mg L(-1)). The results indicated that groundwater level averaged 9.81 m, a level 6 m lower than in 1990. The spatial correlation distances for groundwater level, EC and NO3-N concentration were 21.93, 2.19 and 3.55 km, respectively. The contour map showed that shallow groundwater level areas extended from north to south across the County. Groundwater EC was above 3 dS m(-1) in the most part of the northern county. Groundwater NO3 pollution (NO3-N> or =20 mg L(-1)) mainly occurred in the County Seat areas due to wastewater irrigation and excessive fertilizer leaching from agricultural fields. At Henantuang town, besides suburban of the County Seat, groundwater was also contaminated by NO3 shown by the map generated using the IK method, which was not reflected in the map generated using the OK method. The map generated using the OK method could not reflect correctly the groundwater NO3 pollution status. The IK method is useful to assess the risk of NO3 pollution by giving the conditional probability of NO3 concentration exceeding the threshold value. It is suggested that risk assessment of NO3 pollution is useful for better managing groundwater resource, preventing soil salinization and minimizing NO3 pollution in groundwater.     

Occurrence of 222Rn, 226Ra, 228Ra and U in groundwater in Fujian Province, China

222Rn, 226Ra, 228Ra and U were determined in a total of 552 groundwater samples collected throughout Fujian Province of China. The geometric mean concentrations of 222Rn, 226Ra, 228Ra and total U in the groundwater were 147.8 kBq m-3, 12.7 Bq m-3, 30.2 Bq m-3 and 0.54 microgram kg-1, respectively. High groundwater 222Rn was explained by the predominantly granitic rock aquifers in Fujian. A lifetime risk of 1.7 x 10(-3) was estimated for the ingestion of groundwater 222Rn. High ratios of 228Ra to 226Ra contents (geometric mean of 2.4) and their disproportion suggest that 228Ra should also be measured in the assessment of population doses from drinking water in the regions of high rock or soil 232Th. No significant correlation between the 222Rn concentrations in groundwater and air was found.     

Awareness on usage of contaminated groundwater around Perungudi dumpsite,Tamil Nadu,India

Groundwater is the major drinking water source both in urban and rural area. Mostly in urban and peri-urban areas of developing countries, groundwater is more susceptible to contamination due to urbanization. Therefore, the awareness of usage of groundwater has to be analysed to frame the policy measures and to suggest proper intervention programs. The community residing around Perungudi dumpsite, Tamil Nadu, India, has been chosen to assess the awareness on usage of groundwater using regression model. The groundwater flow and quality analysis assessed technically is in line with people’s perception on groundwater quality. The model results clearly indicate that the socio-economic status (β = 0.167) and distance (β = 0.305) play a major role in groundwater usage. Though 31.2 % of respondents reported that the water quality is bad within 1 km in the contaminated area, 45 % of low socio-economic categories depend on well water. This shows the unawareness of health issues due to the usage of contaminated water. Proper policies have to be framed, especially for the contaminated site to get rid of adverse health impacts due to long-term exposure of contaminated water.     

Contamination of groundwater and risk assessment for arsenic exposure in Ha Nam province, Vietnam

The characteristics of arsenic-contaminated groundwater and the potential risks from the groundwater were investigated. Arsenic contamination in groundwater was found in four villages (Vinh Tru, Bo De, Hoa Hau, Nhan Dao) in Ha Nam province in northern Vietnam. Since the groundwater had been used as one of the main drinking water sources in these regions, groundwater and hair samples were collected in the villages. The concentrations of arsenic in the three villages (Vinh Tru, Bo De, Hoa Hau) significantly exceeded the Vietnamese drinking water standard for arsenic (10 microg/L) with average concentrations of 348, 211, and 325 microg/L, respectively. According to the results of the arsenic speciation testing, the predominant arsenic species in the groundwater existed as arsenite [As(III)]. Elevated concentrations of iron, manganese, and ammonium were also found in the groundwater. Although more than 90% of the arsenic was removed by sand filtration systems used in this region, arsenic concentrations of most treated groundwater were still higher than the drinking water standard. A significant positive correlation was found between the arsenic concentrations in the treated groundwater and in female human hair. The risk assessment for arsenic through drinking water pathways shows both potential chronic and carcinogenic risks to the local community. More than 40% of the people consuming treated groundwater are at chronic risk for arsenic exposure.     

Taxonomy of groundwater quality using multivariate and spatial analyses in the Tuticorin District,Tamil Nadu,India

A holistic appraisal of the quality of groundwater from the Tuticorin District has been conducted using multivariate statistical and spatial analyses. The objectives of the study were to delineate the spatial and temporal variabilities in groundwater quality and to understand its suitability for human uses. A total of 100 groundwater samples were collected and analyzed for major cations and anions during pre-monsoon and post-monsoon. Water quality index rating was calculated to quantify overall water quality for human consumption. The PRM samples exhibit poor quality in greater percentage when compared with POM due to the dilution after rainfall. Correlation, factor analysis, and plot of the factor scores reflect the seawater intrusion and weathering process. The mineral stability diagrams indicated that the groundwater is in equilibrium with kaolinite and Ca-montmorillonite, whereas Gibbs plot showed that the chemical composition of groundwater in both districts is controlled by the natural weathering processes irrespective of seasons. The major water type identified in this study is the Ca²⁺–Mg²⁺–HCO₃ ^? type, which degrades into predominantly Na⁺–Cl^?–SO₄ ^2? more saline groundwater toward the coast.     

Groundwater market and its implications on water resources and agriculture in the southern peri-urban interface,Chennai, India

This paper describes the informal groundwater market existing in the urban–peri-urban interface of Chennai. The private water tanker suppliers and packaged water industries utilize the land and water resources of the peri-urban villages. Thus, the groundwater sources in peri-urban areas play a significant role in meeting the growing urban demand. The villages that are experiencing the groundwater market are highly influenced by the urbanization and its related activities, due to their proximity to the city. The transfer of groundwater from the peri-urban villages not only deprives the peri-urban areas of their water rights but also leads to environmental damage. Agriculture declined in the water marketed villages in the range of 20–95 per cent during 1990–2007. The pre-monsoon and post-monsoon groundwater level fluctuation varied from 2–6 m to 0–5 m, respectively, during 1971–2007. The declining trend of the groundwater table and agriculture is highly significant in the water marketing villages. Moreover, the present groundwater quality is also in a susceptible state due to over extraction. Hence, strengthening the legal and institutional framework to ensure an equitable access to water for both urban and peri-urban areas is urgently required. This paper also describes the characteristics of the groundwater transfer, quantification of the marketed water, the role of the existing regulatory framework, and the institutional mechanisms. Many stakeholder’s meeting and focus group discussions have been conducted in the villages under study for understanding the socio-economic implications of the water market. The study ultimately emphasized a sustainable groundwater extraction/market which will safeguard the interests of the peri-urban and urban communities.     

江苏盐城地区地下水水化学特征及形成机理

为了查明江苏盐城地区深层地下水咸化的主要影响因素,采集了不同类型水样(河水、浅层地下水、深层地下水和海水),通过对该地区不同水体的水化学特征、离子比值以及氘氧氚同位素组成进行分析,研究了盐城地区深层地下水水化学特征的形成机理。结果表明:浅层微咸水主要是溶解地层盐分和蒸发作用形成,而滨海港镇的部分地区受到一定程度的现代海水入侵影响。深层地下水总体为淡水,水化学演化以正常的水-岩作用为主,而深层微咸水主要分布在两个地区,一是东部滨海地区的灌河口至大丰一带,二是内陆地区的大丰市及其周边一带。滨海地区的深层微咸水主要是淋滤古海相地层盐分形成,黄沙港镇部分地区则受到轻微的现代海水入侵影响,而内陆地区的深层微咸水主要是浅层咸水下渗造成的。因此,盐城东部沿海矿化度增高的区域应大力加强对地下水的保护,特别是随着全球变暖,黄海海平面有上升的趋势,东部的滨海港镇等受海水入侵影响较大的区域更应引起高度重视。     

A Hierarchy of Groundwater Management, Land-Use, and Social Needs Integrated for Sustainable Resource Development

The pyramid of human needs developed by Abraham Maslow is based upon the presumption that until a person's lower level needs are fulfilled, higher level needs remain irrelevant. Groundwater and land-use management can likewise utilize such a hierarchy in integrating plans and operations with the needs of the society. Only once a region's population has fulfilled more basic concerns can higher-level groundwater and land-use management needs be effectively achieved. Attaining the ultimate goal of resource sustainability would certainly require considerable public backing, both for financial support and minimizing ambient pollution. For efficient water management to supply a society's water needs for future generations, sustainable groundwater management will require the full support of an educated society. The objective of the authors is to point out how essential it is to integrate operational strategies into regional hierarchies of needs applicable to groundwater management, land-use, and social planning. The situation of groundwater resources in Israel's Sharon Coastal aquifer region is taken as a case in point. Remedial groundwater activities have been undertaken in the management program for this aquifer. But it appears that maximal management efficiency cannot be achieved until the public's basic concerns are satisfactorily addressed and water resources planners reach consensus and a working partnership with the society in question. Operational measures must be clearly shown to benefit the region's population as regards their social, economic, and environmental concerns. This can only be achieved through public education, promoting awareness of the issuesbreak involved.     

Coupled radon, methane and nitrate sensors for large-scale assessment of groundwater discharge and non-point source pollution to coastal waters

We constructed a survey system of radon/methane/nitrate/salinity to find sites of submarine groundwater discharge (SGD) and groundwater nitrate input. We deployed the system in Waquoit Bay and Boston Harbor, MA where we derived SGD rates using a mass balance of radon with methane serving as a fine resolution qualitative indicator of groundwater. In Waquoit Bay we identified several locations of enhanced groundwater discharge, out of which two (Childs and Quashnet Rivers) were studied in more detail. The Childs River was characterized by high nitrate input via groundwater discharge, while the Quashnet River SGD was notable but not a significant source of nitrate. Our radon survey of Boston Harbor revealed several sites with significant SGD, out of these Inner Harbor and parts of Dorchester Bay and Quincy Bay had groundwater fluxes accompanied by significant water column nitrogen concentrations. The survey system has proven effective in revealing areas of SGD and non-point source pollution.     

Tritium concentrations of groundwater in Naka Terrace,Ibaraki Prefecture,Japan

Levels of tritium in groundwater of the inland area of Naka Terrace were measured during 1981–1983 to establish a baseline for evaluation of any changes which may result from release of tritium from nuclear facilities in the coastal region of the terrace. Most of the samples yielded concentrations in the range 40–90 pCi litre⁻¹, which were similar to those of two rivers bordering the area of concern, whereas tritium levels in monthly precipitation samples were in the range 30–50 pCi litre⁻¹. These results imply that the rivers are fed from groundwater reservoirs, which are releasing the higher tritium levels recharged during the previous 20 years when bomb-produced tritium caused higher levels in precipitation. Only two groundwater samples yielded concentrations below detection limit, both from the deep Pleistocene gravel layer in a buried river channel underlying the terrace. Some ground-waters in the coastal area yielding more than 100 pCi litre⁻¹ are considered to be already influenced by tritium released from nuclear facilities.     

川中遂宁地区红层地下水水化学特征及主要离子来源分析

四川红层区居民用水主要为就近开采的地下水,水质参差不齐,研究红层地下水水文地球化学特征,对于宜井区选择,红层水源地用水安全具有重要意义。利用在遂宁船山区采集的70组浅层地下水水样,采用数理统计分析、离子比例关系等方法,分析了红层浅层地下水水化学特征及主要离子来源,研究得出:区内地下水中阴离子以HCO_3~-(164.00～571.91 mg·L~(-1))为主,其次是SO_4~(2-)(13.96～1 000.00 mg·L~(-1)),阳离子以Ca~(2+)(45.70～313.00 mg·L~(-1))为主,其中孔隙水的水化学类型主要为HCO_3,SO_4-Ca,SO_4-Mg型,裂隙水以HCO_3-Ca,Mg型与HCO_3-Ca型为主;地下水中离子成分主要由岩石风化产生,来源于地层中的方解石、白云石、石膏、芒硝等矿物的风化溶解,蒸发浓缩、地下水酸碱环境及人类活动对地下水成分造成了一定的影响;浅层地下水质量以Ⅲ～Ⅳ类为主,污染物主要为TDS、Fe~(3+)等原生污染,也存在NO_3~-、NO_2~-等人类活动污染;红层宜井区主要为平坝、丘坡坡脚及沟谷一带,为避免污染指标超标,井深不宜超过25m,远离养殖场、农厕等地下水易受人类活动污染的环境,防止鱼塘、农田等地表水进入井中。     

Groundwater in the Limpopo Basin: occurrence,use and impact

The Limpopo River Basin is underlain by an alluvial aquifer along the main river stem and fractured water-bearing units in tributary catchments. Notwithstanding that development priorities in parts of the basin in South Africa have historically preferred surface water sources for irrigation and domestic supply, water resources auditing suggests that groundwater presents the only viable alternative source of cost-effective supply to meet future requirements. However, while aquifer yields are favourable in places, averaging 16.7 l/s for main-stem alluvium, groundwater is already extensively used. Between 1995 and 2002, total groundwater use in the area rose by almost 40%, increasing from 98 to 136 million m³ per year. In all catchments, groundwater use grew by varying proportions, reaching a rather high 200% in the Mogalakwena catchment. In the particular case of commercial irrigation, over-exploitation of groundwater has been recorded in a number of places, especially in the northwest where drawdowns of more than 50 m have resulted from decades of intense agricultural water use. Although groundwater use for mining is still low at 4% of total usage in the study area, the region is currently witnessing a surge in mining operations, and a significant growth in water requirements is envisaged for mining development. Further, domestic water supply to the predominantly rural dwellers in the area is relatively low, even in terms of meeting the basic need of 25 l/day per person, underscoring the fact that groundwater will remain a critical source of community drinking water in the foreseeable future. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

The hydrogeochemistry of the Pleistocene aquifer in the Nile Delta area,Egypt

The Pleistocene aquifer represents the main aquifer underlying the Nile Delta area. This aquifer is directly affected by the surface water from the Nile branches. However, the study of the hydrogeochemistry of this aquifer indicates the possibility of classifying it into three hydrochemical zones from south to north. The groundwater chemistry of each zone is the resultant effect of the local factors controlling the development of groundwater quality.     

Sustaining livelihoods in face of groundwater depletion: a case study of Punjab, India

The study focuses on assessing the sustainable livelihoods of farmers in Indian Punjab focusing on the key aspects of cropping pattern, cost of cultivation, agricultural productivity and profitability amongst different classes of farmers at different levels of groundwater depletion. It further gives a comparative analysis of the proportionate gains the farmers avail from the government subsidies of electricity and procurement price and relates it to their coping mechanisms to sustain agriculture in future. The findings indicate to the fact that technology to extract groundwater, being capital intensive, gives greater accessibility to groundwater to large farmers who gain enormously from growing the remunerative but water-intensive rice crop. Electricity subsidy being not targeted is also misappropriated by the resource rich, water extraction machine owners. To cope with this resource depletion, the large farmers dig and deepen more tube-wells and the small and marginal farmers with little savings who are unable to invest in costly water extraction machines, buy water, shift to less profitable maize crop, lease out or sell their land.     

江汉平原东部地区地下水资源的开发利用与保护

根据国家科技攻关的结果，论证了江汉平原东部地区地下水资源的分区和地下水单元的富水性，水质，含水层的水文地质地征，地下水开发利用合理井距，单井开采水量，提出了地下水资源开发利用中的保护对策。     

Uranium groundwater anomalies and L'Aquila earthquake, 6th April 2009 (Italy)

Monitoring of chemical and physical groundwater parameters has been carried out worldwide in seismogenic areas with the aim to test possible correlations between their spatial and temporal variations and strain processes. Uranium (U) groundwater anomalies were observed during the preparation phases of the recent L'Aquila earthquake of 6th April 2009 in the cataclastic rocks near the overthrust fault crossing the deep underground Gran Sasso National Laboratory. The results suggest that U may be used as a potential strain indicator of geodynamic processes occurring before the seismic swarm and the main earthquake shock. Moreover, this justifies the different radon patterns before and after the main shock: the radon releases during and after the earthquake are much than more during the preparatory period because the process does not include only the microfracturing induced by stress-strain activation, but also radon increases accompanying groundwater U anomalies.     

Evaluation of groundwater contamination and its impact: an interdisciplinary approach

The study aimed at determining the socio-economic issues due to municipal solid waste dumping, the extent of groundwater contamination and the groundwater dependency around Perungudi dumpsite in Tamil Nadu, India. Sampling and analysis of groundwater and leachate show the contamination migration is due to dumpsite leachate. The concentrations of contaminants were more severe within 1.5?km along groundwater flow direction mainly due to the geological profile. The Piper diagram also shows that the groundwater sampled within 3?km in the flow direction was classified as Na–Cl type. Studies conducted within contaminated areas to determine the groundwater usage showed that higher percentage of lower and middle socio-economic status categories was using the groundwater for domestic purposes, which may lead to health issues. The present study suggests that proper solid waste management and groundwater remediation techniques along with the people’s involvement are necessary to reduce the consequences of groundwater contamination on the people residing around the dumpsite.     

Climate change and modeling of an unconfined aquifer: the Triffa plain,Morocco

The Triffa plain covering about 307 km² is located in the semiarid region of northeastern Morocco. The cover consists of Quaternary and Mio-Pliocene formations, including alluvial material, silt, sandstone, limestone, clay, and marl, underlain by a sequence of Jurassic carbonates and clastics. Two principal aquifers occur in this region: (1) An unconfined aquifer hosted by the Quaternary formations, which opens up on the coastal plain of Saïdia, giving rise to the Aïn Chebbak and Aïn Zebda springs; and (2) a confined aquifer hosted by the underlying Liassic (Jurassic) formations, composed of limestone and dolostone. In this paper, we present a conceptual hydrogeological model for the Triffa aquifer, which opens laterally into the Saïdia aquifer, based on borehole data, bedrock geology, hydrodynamic parameters, piezometric maps, and time series groundwater level and precipitation data, obtained from several meteorological stations and pumping wells. These comprehensive data were incorporated in the Geographic Information System platform and processed using groundwater modeling software, with the development of the numerical model and its limitations discussed in detail in the present work. Subsequently, we evaluated the impact of climate change on the Triffa aquifer, assuming three different climate scenarios developed by the Intergovernmental Panel on Climate Change. These were the B1—low, A1B—mean, and A1F1—extreme scenarios, which we modeled by simulating a decrease in the recharge in all of the study area up to year 2099 that would correspond to 9, 19, and 47%, respectively. The calibration of the model in steady and transient states produced a good agreement between the observed and simulated heads. The simulation of the impact of climate change on groundwater by a decrease in the recharge highlights the groundwater drawdown occurring in this region. This work can significantly help the authorities in the sustainable management and exploitation of local groundwater.     

Assessment of groundwater potential in Tirukalukundram block of southern Chennai Metropolitan Area

Groundwater is an important resource in all major urban centres. Continuous extraction leads to degradation and depletion in the water quality which can be protected by selecting proper groundwater recharging techniques. The present study aims to determine the groundwater potential by integrating the remote sensing and geographic information system which helps to identify the locations which are in critical stage and immediate steps can be taken to recharge the groundwater. Thirukalukundram block of Kanchipuram district in Tami Nadu, India, has been chosen as study area. To demarcate the groundwater potential zone, surface attributes such as geomorphology, land use/land cover, contour map, drainage density and sub-surface attributes such as lineaments and soil maps are created using satellite imageries, toposheet, soil and geomorphology data of the study area. The thematic maps prepared using geographic information system and weights have been assigned to the attributes by considering the influence on the storage capacity of groundwater. Four categories of groundwater potential zones such as below low, low, moderate and high have been classified. From the analysis, 5% along the coastal plain area covers high groundwater potential zone, 20% of the area towards north-west and south-west hold moderate groundwater potential. 60% of the total area hold low groundwater potential zone which are located towards south-west direction. 15% of the study area contains below low groundwater potential zone in parts of south-west direction. This study helps to identify the suitable locations for extraction and recharge of groundwater.     

Apparent 85Kr ages of groundwater within the Royal watershed, Maine, USA

Specific 85Kr activity is mapped from 264 domestic and municipal wells sampled during 2002-2004 in the Royal watershed (361 km2), Maine. Gas samples are collected at 20 m, 40 m, and > 50 m interval depths within the unconfined aquifers. Gas extraction for 85Kr from wells is obtained directly via a wellhead methodology avoiding conventional collection of large sample volumes. Atmospheric 85Kr input to the recharge environment is estimated at 1.27 Bq m(-3) by time-series analyses of weighted monthly precipitation (2001-2004). Numerical simulation of Kr gas transport through the variable unsaturated zones to the water table suggests up to 12-year time lags locally, thus biasing the 85Kr groundwater ages. Apparent 85Kr ages suggest that approximately 70% of groundwater near 20 m depth was recharged less than 30 years BP (2004). Mass-age transport modeling suggests that post mid-1950s recharge penetrates to part of the basin's floor and that older groundwater seeps from the underlying fractured bedrock may occur.