Analytical data of groundwater samples collected from weathered and deep fractured zones in the Precambrian charnockite aquifers in Kerala, India, have been studied to understand their hydrochemical variations and reasons thereof. Concentrations of the majority of the constituents analyzed were found to increase with increasing depth of aquifers, with the exception of nitrate. Studies indicate that various processes such as ion exchange reactions, carbonate weathering and silicate weathering are active in both the aquifers which influence the hydrochemical composition of groundwater in them. The prevailing groundwater quality in the aquifers is dependent on the dominance of each process in relation to others. Principal component analysis of the data suggests that contamination from anthropogenic sources has a major role in determining the hydrochemical characteristics of groundwater in the weathered zone unlike in the case of fractured aquifers where water-rock interaction is the major factor responsible. The study also indicates limited hydraulic connection between the weathered and fractured aquifers at the local scale.

Spatial distribution of radon in groundwater in the coastal tracts of southern Kerala, India was studied to understand its linkage with the monazite bearing beach sand deposits in the area. The mean radon concentrations were below the guideline value recommended by United States Environmental Protection Agency in about 94 % samples analyzed. Annual effective ingestion and inhalation doses of water-borne radon were found to be well below the average doses reported from all natural sources. The study indicated that radionuclides in the monazite-rich beach sands do not contribute significantly to the radon concentration in groundwater in the area.

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