Chemistry and behaviour of B, Ca and Mg in interstitial waters of sediments from the coastal and estuarine regions of Mandovi River along the West Coast of India

Abstract

Interstitial waters of coastal and estuarine sediments show enrichment of B and Ca and a decrease in Mg. Increase in interstitial B in sediments is due to the downward diffusion from overlying water and release from solid phases by physicochemical endogenous processes. Mg decrease is due to its uptake by clay minerals having a greater cation exchange capacity under reducing conditions. Ca²⁺ and Mg²⁺ released from carbonates at lower pH in sediments are governed by some physicochemical processes. Salinity remains high in most of the sediments rich in clay and silt as compared to the sandy sediments, due to the semi-permeable character of clay and silt. Organic carbon in sediments (av. 1.6%) does not seem to indicate a definite relation with B but affects <i>p</i>H, indicating the releases of acidic compounds by the breakdown of organic matter.