Sources, vertical fluxes and accumulation of petroleum hydrocarbons in sediments from the Mandovi Estuary, west coast of India

Abstract

The Mandovi estuary is highly influenced by mining and tourism related activities in the central west coast of India. Vertical fluxes and accumulation of petroleum hydrocarbons (PHCs) in three sediment cores (D1, C1 and OG) from the Mandovi estuary were assessed using Ultra-Violet Fluorescence (UVF) spectroscopy. The range of PHCs values in estuarine sediments varied from 5.4 to 12.34 μg/g Enrichment of PHCs values in the upper parts of three sediment cores were mostly derived from terrestrial and marine related sources including petrogenic (discharge of land based effluents and petroleum products), pyrogenic (emission of fly ash from industries and vehicles and combustion of petrol from ore-filled barges, boats and ships) and biogenic (mangrove vegetation along the banks of the estuary) sources. The significant positive relationship between mud (silt + clay) and PHCs unveiled that high specific surface of area of mud content raise the level of petroleum hydrocarbons. Cluster analysis was used to discriminate the sediment samples based on their degree of contamination. Values of PHCs in the upper part of sediment cores were distinctly higher than the background but were lower than those found in the Thane creek, west coast India (7.6-42.8 μg/g) and off Chennai, east coast of India (1.8-39.72 μg/g). This baseline PHCs data can be used for regular ecological monitoring and effective management for the mining and tourism related activities in the Mandovi estuary