An investigative study on subsurface water chemistry near agricultural and aquaculture areas

Water is essential for all types of living beings. Application of fertilisers in agriculture became a prime source for contamination of subsurface waters. Backwaters from aquaculture can also contaminate the groundwater sources. The study aimed at assessing the chemical and metal toxicity for evaluating water quality. The quality of water was assessed during pre monsoon season between February and May 2017 and post monsoon season between October 2017 and January 2017. pH is measured using portable pH metre, electrical conductance(EC) is measured using portable EC sensor, total dissolved solids (TDS) is measured by portable TDS sensor, DO is measured by DO metre, total hardness (TH), total alkalinity (TA), CO32−, HCO3−, Cl−, Ca2+, Mg2+ are measured by titrimetry, SO42− and PO43− are measured by spectrophotometer, NO3− by using ion selective electrode, Na+ and K+ by Flame photometer and metal ions like Cr, Mn, Fe, Co, Ni, Cu, Zn, Pb, As and Hg by inductively coupled plasma optical emission spectroscopy technique (ICP-OES). The analytical results showed that during pre monsoon season in both agricultural and aquaculture areas Cr, Mn, Fe, Co, Ni, Cu, Zn, Pb, Hg are below the guideline values of IS and WHO. The concentration of As and Cu metal ions during post monsoon season are higher than the guideline value of WHO. In waters near agricultural areas TDS and TH were observed to be higher than the guideline values of IS. In waters near aquaculture areas TDS, TH, TA, Chloride, Magnesium, Sodium and Potassium were observed to be higher than the guideline values of IS.