Sub-Surface Investigations on Deep Saline Groundwater of Charnockite Rock Formation, Kalpakkam, India

Self Cite

Groundwater samples from the shallow unconfined aquifer were collected from fifteen borewells in Kalpakkam nuclear plant site and were analysed for various physico-chemical parameters. The pH, temperature, salinity, TDS and EC were measured in the field. The borewell samples were analysed in the laboratory for Ca(2+), Mg(2+), Na(+), Cl(-), CO(2-)(3), HC(O-)(3), N(O-)(3) and SO(2-)(4). The Piper Trilinear diagram showed that majority of the borewell samples fall in Na - Cl +SO(4) type and Na - CO(3)+HCO(3) type. The Cl: HCO3 ratio of some borewell samples are categorized under injuriously contaminated to highly injurious type. The higher salinity levels encountered in some borewells emphasized the need for better understanding of groundwater corrosiveness. Accordingly, the Langeliar saturation Index (SI), Aggressivity index (AI) and Larson ratio (LnR) were evaluated for assessing the corrosive nature of the groundwater. The saline water incursion in the southern part of the study area increased the ionic concentration of Cl(-) and [Formula: see text] that made the groundwater corrosive.

Section: Study Areamentioning

confidence: 93%

Section: Groundwater Chemistrymentioning

confidence: 99%

Section: Geologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Assessment of groundwater corrosiveness for unconfined aquifer system at Kalpakkam

Sasidhar

Kumar

2008

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“…In pre-monsoon (June 2003 pH log 10 H + , EC electrical conductivity in μS/cm, TDS total dissolved solids in mg/l, TH total hardness in mg/l, ND not detected, all ions are in mg/l, SD standard deviation a During monsoon period in October-November (Gurumoorthy et al 2004) to 20,533 μS/cm due to the saline water incursion. The increase of EC with such a large variation is of a major concern most probably because of infiltrated seawater/Buckingham canal water, together with the contribution from the possible opening of fractures and shear zones of the charnockite rock after the monsoon period, which was observed more effectively in shallow aquifers at various locations in this area, because TDS values were 45,120 and 40, 860 mg/l (see Table 2) for Buckingham canal water and seawater of the Bay of Bengal, respectively.…”

Section: Resultsmentioning

confidence: 99%

Assessment of seawater impact using major hydrochemical ions: a case study from Sadras, Tamilnadu, India

Mondal

Singh

Saxena³

et al. 2010

The impact of seawater intrusion was investigated using major hydrogeochemical ions to evaluate the origin of salinity in Sadras watershed located between Buckingham Canal and Bay of Bengal in the southeastern coast of India. From empirical data collected twice during pre- and post-monsoon seasons, it was found that groundwater was slightly acidic to mildly alkaline, and more than 44% of groundwater samples had EC > 3,000 μS/cm in both the seasons. Results of principle component analysis (PCA) showed that Na( + ), Cl( - ), Mg(2 + ), and SO[Formula: see text] concentrations had the highest loading factor and the samples affected by saline/seawater were separated from the cluster. Hydrochemical processes that accompany the saline/seawater were identified using ionic changes. It was observed during sampling periods that the mixing due to saline/seawater intrusion varied from 4.82-7.86%. Negative values of ionic change (e (change)) for Na( + ) and K( + ) decreased with the increasing fraction of seawater. Furthermore, salinity, sodium adsorption ratio, percentage of sodium Na (%), and exchangeable sodium percentage in well samples showed that groundwater was unsuitable for irrigation purposes.

Groundwater nitrate contamination and use of Cl/Br ratio for source appointment

Samantara

Padhi

Satpathy

et al. 2015

Source appointment for groundwater nitrate contamination is critical in prioritizing effective strategy for its mitigation. Here, we assessed the use of Cl/Br ratio and statistical correlation of hydro-chemical parameters to identify the nitrate source to the groundwater. A total of 228 samples from 19 domestic wells distributed throughout the study area were collected during June 2011-May 2012 and analyzed for various physicochemical parameters. Study area was divided into three spatial zones based on demographic features, viz., northern, southern, and central part. Nitrate concentration in 57 % of samples exceeded the prescribed safe limit for drinking stipulated by the World Health Organization (WHO) and Bureau of Indian standards (BIS). The central part of the study area showed elevated nitrate concentration ranging from below detection limit (BDL) to 263.5 mg/l as NO3 (-) and demonstrated high attenuation within the immediate vicinity thereby restricting diffusion of the nitrate to the adjacent parts. Resolution of correlation matrix as statistical indicator for nitrate contamination was poor. Seventy-seven percent of samples with high nitrate concentration (>45 mg/l as NO3 (-)) showed strong association with high Cl/Br mass ratio (350-900), indicating mixing of sewage and septic tank effluents with groundwater as a primary source for the nitrate in the studied area. Nitrate level during monsoon (BDL, 229.9 mg/l as NO3 (-)), post-monsoon (BDL, 263.5 mg/l as NO3 (-)), and pre-monsoon (0.5-223.1 mg/l as NO3 (-)) indicated additional contribution of surface leaching to groundwater.