Groundwater Arsenic Contamination from Parts of the Ghaghara Basin, India: Influence of fluvial Geomorphology and Quaternary Morphostratigraphy
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Appl Water Sci DOI 10.1007/s13201-016-0459-3 ORIGINAL ARTICLE Groundwater arsenic contamination from parts of the Ghaghara Basin, India: influence of fluvial geomorphology and Quaternary morphostratigraphy Babar Ali Shah1 Received: 13 June 2015 / Accepted: 31 August 2016 Ó The Author(s) 2016. This article is published with open access at Springerlink.com Abstract A groundwater arsenic (As) distribution in were likely deposited from the Himalayas. The process of Faizabad, Gonda, and Basti districts of Uttar Pradesh is release of groundwater arsenic is reductive dissolution of shown in the entrenched channels and floodplains of the iron hydroxides. Ghaghara River. Tubewell water samples were analysed for As through flow injection hydride generation atomic Keywords Groundwater arsenic Á Ghaghara Basin Á Older absorption spectrometry (FI-HG-AAS) system. About 38, alluvium Á Holocene aquifer Á Geomorphology 61, and 42 % of tubewells in Faizabad, Gonda, and Basti districts, respectively, have As [10 lg/l (WHO guideline). Moreover, 15, 45, and 26 % of tubewells in Faizabad, Introduction Gonda, and Basti districts, respectively, have As above 50 lg/l. About 86, 69, and 35 % of tubewells in Faizabad, Arsenic (As) is found in soil and groundwater by natural Gonda, and Basti districts, respectively, are from shallow and anthropogenic sources. High concentrations of As is depth (21–45 m), and it is worth noticing that 47 % As- one of the most hazardous chemical elements in drinking contaminated (As [10 lg/l) tubewells in these three dis- water in several parts of the world. Millions of tubewells in tricts are located within the depth of 10–35 m in Holocene the Ganges–Brahmaputra–Meghna (GBM) delta plain are Newer Alluvium aquifers. The high content of As As-contaminated in the groundwater (Ravenscroft et al. (7.11 mg/kg) is measured in suspended river sediments of 2009). Although the major switch from polluted surface the Ghaghara River. Most of the As-contaminated villages water to groundwater in early 1970s helped people to avoid in the Ghaghara Basin are located close to abandoned or waterborne diseases, but naturally occurring high concen- present meander channels and floodplains of the Ghaghara tration of dissolved As in groundwater of alluvial aquifers River. In contrast, tubewells in Faizabad, Ayodhya, and has been causing serious health problems in millions of Nawabganj towns are As-safe because of their positions on people for the last three decades. The upper permissible the Pleistocene Older Alluvium upland surfaces. Quater- limit of As in drinking water is 10 lg/l in WHO guideline nary geomorphology plays an important role in ground- (WHO 1993) which has been endorsed by Bureau of Indian water arsenic contamination in the Ghaghara Basin. The Standards (BIS 2003). The mode of occurrence, origin, and sources of groundwater arsenic are geogenic and perennial mobility of As in sedimentary aquifers in the Bengal Delta mountainous rivers in the Ghaghara Basin supplied high and other fluvial-deltaic setting in different parts of the sediment loads. The arsenic in groundwater of Ghaghara world are mainly influenced by local geology, geomor- Basin is getting released from associated sediments which phology, hydrogeology, and geochemistry of sediments and water, as well as anthropogenic activities (Nickson et al. 1998; Acharyya et al. 2000; Kinnibugh and Smedley & Babar Ali Shah 2001). The worst As-affected regions in Asia are mainly [email protected] Bangladesh and West Bengal in India (Dhar et al. 1997; 1 Department of Geological Sciences, Jadavpur University, Nickson et al. 1998; Acharyya et al. 2000; Kinnibugh and Kolkata 700032, India Smedley 2001; Acharyya and Shah 2007, 2010; von 123 Appl Water Sci Bro¨mssen et al. 2007; Ravenscroft et al. 2009; Shamsud- to join the Ganga River. The Ghaghara River adopts a duha et al. 2008). Arsenic pollution in groundwater is also meandering path through the alluvial plains, frequently reported from South, West and East Asia viz., Pakistan, shifting their courses and forming ox-bow lakes. The People Republic of China, Taiwan, Vietnam, Laos and topography of the area is heterogeneous; varying between Cambodia, Nepal, Egypt and Yemen (Tseng et al. 2000; upland surfaces, plain areas and low-lying small natural Berg et al. 2001; Mondal and Suzuki 2002; Nickson et al. bodies, viz., swamp and ponds. The Older Alluvium is 2005; Gurung et al. 2005; Al-Mikhlafi 2010; Kashouty located at an elevation of 10–20 m above the river level et al. 2012). and constitutes the higher interfluve areas. The Pleistocene Recently, groundwater As contamination has been Older Alluvium surfaces in the Ghaghara Basin are char- reported from the Middle Ganga Plain in the states of acterized by yellow–brown coloured sediments with pro- Jharkhand, Bihar, and Uttar Pradesh (Chakraborty et al. fuse calcareous and ferruginous concretions (Fig. 3). 2003; Bhattacharjee et al. 2005; Shah 2008). The Ghaghara Newer Alluvium forms the river valley terrace and is River is a distributary of the River Ganges and is a sig- located at an elevation of 5–10 m above river level. The nificant river in UP with many cities, towns and villages Holocene Newer Alluvium surfaces are recognized by grey are located on its bank (Fig. 1). This study is undertaken to black coloured organic-rich argillaceous sediments in for groundwater As distribution in Faizabad, Gonda, and entrenched channels and floodplains of the Ghaghara River Basti districts of Uttar Pradesh involving tubewells within (Fig. 3). The area is under humid subtropical climate and Holocene Newer Alluvium aquifers, as well as, Pleistocene the annual average rainfall is 1041 mm. Temperature ran- Older Alluvium aquifers. The main objective of the study ges between maximum (47 °C) in summer and minimum is to investigate the distribution of groundwater As in (2 °C) in winter. entrenched channels and floodplains of the Ghaghara River The distribution of groundwater As in the Ghaghara under Quaternary geomorphological setting (Fig. 2). Basin is prepared based on the Survey of India topographic sheets (63J/1, J/2, J/5, and J/6) in 1:50,000 scale, with field checks to identify fluvial landforms and soil characters. Study area The study areas in Faizabad, Gonda, and Basti districts along entrenched channels and floodplains of the Ghaghara The Ghaghara River has originated from Matsatung glacier River are shown in Fig. 2. In this study, approximately in the Himalayas near Mansarovar Lake in Tibet and 1500 km2 areas have been mapped to delineate ground- traveled a distance of about 1080 km in NW–SE direction, water As-contaminated and As-safe areas. Fig. 1 Quaternary sediments in the Indo-Ganga Basin and Bengal Basin. The study area in the Ghaghara Basin is shown in Fig. 2. A Allahabad, V Varanasi, BX Buxar, B Ballia, C Chappra, P Patna, BG Bhagalpur 123 Appl Water Sci Fig. 2 Groundwater arsenic distribution in Faizabad, Gonda, and Basti districts of Uttar Pradesh Pleistocene to Recent) in order of superposition. The Siwalik Supergroup is further subdivided into Lower, Middle, and Upper groups ranging in age from Middle Miocene to Early Pleistocene in northern part of the Siwalik Basin forming the Outer Himalaya. The Banda Group in the southern part of the basin corresponds to the Upper Siwalik (Kumar et al. 1996). The sediments formed Bandra Older Alluvium which is characterized by variegated clays followed by the clastic sediments. However, the sediments derived from the Himalayas in northern part of the basin constitute the Upper Siwalik (Dwivedi et al. 1997). The Ghaghara Valley in the Ganga Plain consists of thick pile of Quaternary sediments. Geomorphologically, the Older Alluvium surfaces, i.e. the Varanasi Older Alluvium constitute upland surfaces which are also rec- ognized as the Bhangar surface and are occupying a major part of the area. The Varanasi Older Alluvium consists dominantly of multiple fill polycyclic sequence of sand, silt, and clay (Kumar et al. 1996). In the Ghaghara Basin, Fig. 3 Pleistocene Older Alluvium sediments (a) with calcareous and the top 3 m part is of silt–clay facies corresponding to ferruginous concretion (k) in Faizabad areas. Entrenched channels and floodplains of the Ghaghara River (b) suspension load of floodplain environment underlain by arenaceous facies corresponding to channel fill palaeoen- Geological setting vironment. The subsurface boreholes down to a depth of 300 m record a number of calcrete (kankar) and argilla- The Quaternary geology of the Indo-Gangetic plains has ceous bands at various levels (Dwivedi et al. 1997). been subdivided the sediments into Older Alluvium and The river Ghaghara draining the area has developed a Newer Alluvium (Pascoe 1964). This classification was second geomorphic unit, the low-lying floodplains—the revised by Pathak et al. (1978) as Upper Siwalik (Upper Khadar surface of the river. The main geomorphic features Pliocene to Lower Pleistocene), Older Alluvium (Middle to are giant channel bar, natural levee, and floodplains. The Upper Pleistocene), and Newer Alluvium (Upper Holocene Newer Alluvium comprises grey to black 123 Appl Water Sci coloured organic-rich argillaceous sediments in entrenched minimum determination limit of Kit is 10 lg/l. Kit data channels and floodplains of the Ghaghara River. The top was used as a guide to delineate As-contaminated and As- thin layer of silt–clay has been deposited in a lacustrine safe areas in the field. In this study, 231 tubewell water condition towards the close of sedimentation. The land- samples from the above districts were tested in the scape of the study area is typically fluvial, characterized laboratory. mainly by active channels, abandoned channels, natural The geographic location of each tubewell was recorded levees, back swamps, and floodplains. The Quaternary by a global positioning system (Garmin eTrex Vista), and lithostratigraphy in the Ghaghara Basin has been classified the depth of the tubewell was acquired through personal broadly into two units, i.e.