Processes and metal enrichment of adjacent mudflat and mangrove environments in the middle estuarine regions of tropical Mandovi Estuary, Goa, west coast of India

Abstract

Two sediment cores collected each one from mangrove and mudflat environments of Mandovi Estuary near Dr. Salim Ali Bird Sanctuary, Chorao, Goa, were studied for grain size, organic carbon, and metals-Fe, Mn, Cr, Zn to understand the processes, depositional environments, and metal distribution. The study documents how adjacent ecosystems can help in understanding metals distribution and their enrichment. The average data indicated relatively higher silt, clay, organic carbon, biogenic silica, Fe, Mn, and Zn in mangrove core while higher sand and Cr in mudflat core. The sediments in both the environments were deposited in less varying hydrodynamic conditions with time. The metal remobilization from deeper sediment towards the surface as well as between mudflats to mangrove environments was observed. Geo-accumulation Index (Igeo) and anthropogenic factor (AF) employed to understand the level of metal enrichment indicated that the sediments of the mangrove environment were moderately polluted while that of the mudflat environment was practically unpolluted.