Geochemical and diatom records of recent changes in depositional environment of a tropical wetland, central west coast of India

• Published in: Environmental earth sciences Vol. 73; no. 9; pp. 5447 - 5461
• Main Authors: Pande, Anant, Nayak, G. N, Prasad, Vandana, PrakashBabu, C
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01-05-2015; Springer Berlin Heidelberg; Springer Nature B.V
• Subjects: Algae; Bacillariophyceae; Bacillariophycidae; Biogeosciences; Carbon; carbon nitrogen ratio; Climate change; Coasts; Earth and Environmental Science; Earth Sciences; Environmental Science and Engineering; freshwater; Geochemistry; Geology; Hydrology/Water Resources; Marine environment; metals; Mud flats; Nitrogen; nitrogen content; Organic carbon; Organic matter; Original Article; Pollution control; River basins; River flow; Rivers; Runoff; sand; Sediments; temporal variation; Terrestrial Pollution; trace elements; Trace metals; Wastewater treatment; Water pollution; Water treatment; Wetlands; India; ISW, India; Depositional environment; Geochemical; Central west coast of India; Diatoms; Wetlands
• ISSN: 1866-6280; 1866-6299
• DOI: 10.1007/s12665-014-3799-z

Two mudflat sediment cores collected from a sub-channel (S-61) and the main channel (S-60) of a tropical wetland, along central west coast of India, were investigated for recent changes in depositional environment using geochemical (sediment grain size, total organic carbon, total nitrogen, carbon/nitrogen ratio (TOC/TN), selected metals and pH) and diatom records. The sub-channel (S-61) represents river environment which opens into main channel (S-60) which represents marine environment being close to the sea. We report a transition from river-dominated to marine-dominated depositional environment over the years. The relatively higher sand percentage together with elevated carbon/nitrogen ratio and predominance of freshwater diatoms suggested greater river runoff in the past while marine influence is supported by decrease in TOC/TN ratio and increased dominance of marine diatoms in recent years. In the main channel (S-60), distribution of metals is regulated by organic matter (total nitrogen and total organic carbon) while in the sub-channel (S-61), Fe–Mn oxyhydroxides play a significant role in trace metal distribution. The highest numbers of diatoms were recorded in the sub-channel (S-61) which is also characterized by higher total nitrogen concentration. Geochemical and diatom signatures thus have helped to infer spatial and temporal variations in depositional environment.