Chemical Evolution of Groundwater in the Coral Islands of Lakshadweep Archipelago, India with Special Reference to Kavaratti Island
Najeeb K. Md and N. Vinayachandran
Journal Title:Nature Environment and Pollution Technology
This paper discusses the unique hydrochemical environment of Lakshadweep Archipelago, a cluster of coral islands, where groundwater exists in the form of a thin freshwater lens over the saltwater, having restricted lateral movements. The influence exerted by the shape of these tiny islands on the stability of the water in the lenses and the tendency of this water to mix with seawater are elucidated. The factors which influence the chemical evolution of groundwater in these islands, such as the geochemistry of the coral aquifer, mixing of sea water, dissolution of CaCO3, marine aerosols and cation-exchange processes are discussed. Mixing of seawater was found to be the predominant process controlling the configuration of freshwater lenses in these islands, as reflected in the ion-ratio studies and the major ionic species observed. The hydrochemical facies, identified with the freshwater lens, represents various phases of mixing. Metabolism of the biological organisms and diagenesis of the lime shells in the corals are responsible for the relatively higher concentration of trace metals, such as strontium and iodide in this aquifer system.