Temporary Fluoride Concentration Changes in Groundwater in the Context of Impact Assessment in the Vaniyar Sub-Basin, South Indi
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Acta Geochim (2017) 36(1):112–123 DOI 10.1007/s11631-016-0137-z ORIGINAL ARTICLE Temporary fluoride concentration changes in groundwater in the context of impact assessment in the Vaniyar sub-basin, South India 1 1 1 S. Satheeshkumar • S. Venkateswaran • R. Kannan Received: 25 July 2016 / Revised: 14 December 2016 / Accepted: 20 December 2016 / Published online: 4 January 2017 Ó The Author(s) 2017. This article is published with open access at Springerlink.com Abstract India’s surface water and groundwater distribu- included Pappiredipatti, Nambiyappati, Menasi, Harur, tion is temporally variable due to the monsoon. Agriculture Todampatti, and Adikarapatti. Data demonstrated is one of the dominant economic sectors in India. improved groundwater quality in the area of the ARS. Groundwater quality is regularly assessed to determine Through recharge, the non-potable fluoride in the region is usability for drinking and irrigation. In this study, World reduced to the permissible limit for human consumption. Health Organization and Bureau of Indian Standards guidelines were used to determine suitability of ground- Keywords Drinking purposes Á Salinity Á Check dam Á water near artificial recharge structures (ARS) with a focus Fluoride Á Dental fluorosis on the structures´ impact on groundwater quality. Ground- water resources were evaluated for irrigation suitability using electrical conductivity (EC), sodium adsorption ratio, 1 Introduction the US Salinity Laboratory diagram, sodium concentration, Wilcox’s diagram, Kelly’s index, and Doneen’s perme- Most groundwater recharge in Tamil Nadu is from rainfall ability index. EC and major ions were tested in recharge associated with the northeast monsoon. Groundwater areas at different distances from the ARS. The construction development has accelerated in recent years, giving rise to of ARS at optimal distances along major streams has the practice of managed aquifer recharge. The suitability of improved groundwater quantity and quality in the sub- groundwater resources for drinking depends on various basin. Before construction of ARS, fluoride concentrations constituents, such as major and minor ions and dissolved were higher; after construction, fluoride was reduced in inorganic, organic, radiological, and biological con- most locations. Water stored in the check dam and stituents. The Bureau of Indian Standards (BIS 2003) and groundwater in the wells closer to the structure were suit- the World Health Organization (WHO 2006) have pre- able for both drinking and irrigation purposes. Impact of scribed permissible limits for various dissolved ions in ARS on nearby groundwater quality was observed at Pal- water. In India, various groundwater recharge studies have lipatti, Mulayanur, Venkadasamuthram, Pudupatti, been carried out based on these standards. Several Poyyappatti, Harur1, and Sekkampatti. More distant sites researchers have discussed the mediating impact of artifi- cial recharge structures (ARS) on groundwater fluoride concentrations (Patel 2002; Mudrakartha 2003; Bhagavan & S. Satheeshkumar and Raghu 2005; Gale 2006; Palanisami et al. 2006; [email protected] Bijukumar and Abraham 2009; Samarah et al. 2009; S. Venkateswaran Venkateswaran 2010; Brindha and Elango 2012; Ren- [email protected] ganayaki and Elango 2013, 2014; Venkateswaran et al. R. Kannan 2015; Pazand 2016). Water quality is important not only in [email protected] drinking water, but for irrigation as well—to ensure max- 1 Department of Geology, Periyar University, Salem, imum yield from the crops. The concentration of dissolved Tamil Nadu 636011, India ions must remain below the recommended permissible 123 Acta Geochim (2017) 36(1):112–123 113 limits to ensure acceptable quality for drinking and irri- recharge in the sub-basin. Agricultural activity takes place gation. ARS are the most common form of water conser- throughout the year, and depends mainly on groundwater vation, indirectly recharging aquifer systems in the sub- resources from dug wells and bore wells. The Tamil Nadu basin. In order to meet local water demand, ARS are Water Supply and Drainage Board tap groundwater to constructed to store significant amounts of water. Existing supply water to the houses in nearby villages. The residents ARS may impact groundwater quality irrespective of also use centrifugal pumps to tap additional groundwater drainage systems and catchment areas. At present, the for domestic purposes. Geologically, the study area is momentum is towards using monsoon runoff to recharge underlain mainly by charnockite and epidote-hornblende depleting aquifers, with no consideration for the water gneiss. quality of the source water (Chadha 2014). Poor water quality can cause the recharging well to clog and the aquifers to become polluted with pathogens, causing water- 2 Methods and data collection borne diseases in the sub-basin. Additionally, various materials in the de-silting chambers can cause water quality Historical groundwater quality data were collected from problems to the recharged aquifers. the public works department (PWD). To supplement his- torical data, samples were collected in the monsoon season 1.1 Details of study area and the wells were concurrently inspected to assess the well type. Groundwater samples were collected from in and The study area is in the Vaniyar sub-basin of the Ponnaiyar around ARS in the sub-basin, and analyzed for pH; elec- River basin, southern India (Fig. 1). The Vaniyar River trical conductivity (EC); and calcium, magnesium, sodium, flows northeastward in the Dharmapuri district of Tamil potassium, carbonate, bicarbonate, chloride, fluoride, and Nadu. The amount of rainfall during the Southwest Mon- sulfate concentrations. Groundwater level and EC were soon is typically high, but can be highly variable. Major measured in all wells. Representative wells at various and minor ARS were constructed across major streams in distances from the ARS were chosen for periodic the sub-basin. Rainfall is the major source of groundwater evaluation. Fig. 1 Map showing artificial recharge structures with monitoring wells 123 114 Acta Geochim (2017) 36(1):112–123 3 Results and discussion 3.3 Groundwater quality for drinking purposes Groundwater quality was assessed for suitability for Various parameters of groundwater quality are shown in drinking based on fluoride and pH concentration across a Table 1. The abundance of major cation concentration in diverse region of the study area as shown in Fig. 2. His- groundwater is Na [ Ca [ Mg [ K, while that of anions is torical data suggest fluoride in excess of the permissible HCO3 [ Cl [ SO4 [ CO3. The groundwater from near the limit can be attributed to over-withdrawal of groundwater ARS was of Na–Cl type. The average pH of groundwater and scarcity of rainfall. There was an increase in pH versus around ARS was 7.49 and beyond in the check dam, it was fluoride in some locations in the summer season and 7.53. EC and TDS are important parameters, as prolonged changes in fluoride were observed at Menasi, K. Vetripatti, use of drinking water with high EC may cause gastroin- and Kadattur. The worst water quality was observed at testinal irritation for humans (Singh et al. 2008). The EC of Kadattur in 2008 due to low rainfall. Fluoride and TDS the groundwater samples in the study area ranged from 213 concentration (Fig. 3), which are low value region indi- to 5162.67 lS/cm with an average of 1627.7. The pre- cated dilution in groundwater during rainy season. Mini- scribed limit of EC is 1500 lS/cm. The water quality types mum, maximum, and average of various parameters in (Piper 1944) can be quickly identified by the location of groundwater quality are shown in Table 1. points in different zones of the diamond shaped Recharge areas were identified from the check dams in field (Fig. 9). the region through assessment of total dissolved solids The suitability of groundwater for drinking purposes (TDS) and major ion concentrations (Renganayaki and depends on pH and major ions remaining under the Elango 2013). It is essential to safeguard water used for limits suggested by WHO (2006) and BIS (2003). drinking and irrigation purposes. Maximum and minimum After construction of ARS, pH and bicarbonate and fluoride concentration are shown in Fig. 4. Both Salur and sulfate concentrations in groundwater were found to be Kadattur recorded values [3 ppm, with values increasing within the permissible limits as per WHO and BIS with distance from the check dam. guidelines. The minimum, maximum, and average total hardness were 134 (at Gopinathampatti), 1588 (at Samiyapuram), 3.1 Fluoride concentration and 490.9 mg/L, respectively. The groundwater samples collected around ARS are shown in the Durov diagram Analysis of groundwater samples revealed concentrations of (Fig. 10). Some drinking water samples in case 1 are Ca- fluoride in excess of permissible limits for drinking (Fig. 4). and SO -dominant, commonly indicative of recharge In most cases, the source is thought to be dissolution of flu- 4 water in gypsiferous deposits; a mixed water or water oride-bearing minerals in granites and gneisses in the study exhibiting simple dissolution may be indicated. In case 2, area. It was also observed that deeper groundwater was more there are no dominant anions or cations, indicating sim- prone to fluoride contamination in comparison to the shallow ple dissolution or mixing. In case 3, Cl and Na are weathered zone. High fluoride in groundwater due to the dominant cations, indicating that the groundwater is geologic environment is a considerable health problem in related to reverse ion exchange of Na–Cl waters. In case India and essential remedial measures are needed to combat 4, Cl and Na dominance normally indicate end-points of an increasing occurrence of fluorosis, both dental and waters. skeletal (CGWB 2008) TDS concentration decreased in groundwater by rainy season (Fig. 5). 3.4 Groundwater quality for irrigation purposes 3.2 Rainfall influence The pH of groundwater and water in the check dam was less than the prescribed 8.2 maximum limit for irrigation Rainfall is a crucial climatic factor that influences water purposes (Ayers and Westcot 1994).