Seawater intrusion and behaviour of dissolved boron, fluoride, calcium, magnesium and nutrients in Vashisti Estuary

Abstract

Behaviour of dissolved B, F, Ca, Mg and nutrients in partially stratified estuary of Vashiti River, Karnataka, India has been studied under stable conditions of riverine flow. The dominance of Mg over Ca concentration in river water resulted in unusually low Ca/Mg molar ratio of 0.32 while the levels of B and F compared well with the composition of average global river water. F, Ca and Mg, were conservative at chlorinities above 4 x 10 sup(3) while variable addition was evident in case of B, Ca and Mg at low chlorinities. Upto 25% removal of B also occurred in the intermediate chlorinity range. Mineralization of organic matter in the mid-estuarine region supplemented the nutrient budget of the estuary along with that associated with the tidal influx of sea water. However, low and variable N/P ratio was suggestive of other source of P in addition to mineralization.