Temporal and spatial variability of trace metals in suspended matter of the Mandovi estuary, central west coast of India

Abstract

Studies on the suspended particulate matter (SPM) in the Mandovi estuary, western India indicate that during the monsoon and pre-monsoon, the SPM increases, and the major and trace metals decrease from stations in the upstream to downstream of the estuary. SPM is consistently low at all stations during the post-monsoon. Trace metals (Cu, Ni, Zn, Cr, and Pb) show strong inter-relationships. They correlate well with Fe and Mn only during the monsoon. The concentrations of Cr, Cu, and Pb are high during the post-monsoon. Enrichment factors and I geo values of metals indicate that Mn shows significant to strong pollution in all seasons, while Cr, Ni, and Zn during monsoon, and Cr during the post-monsoon show moderate pollution. SPM is controlled by the turbidity maximum, while major and trace metals are governed seasonally by a combination of river discharge, resuspension, spillage of Fe-Mn particulates, and anthropogenic contamination. Incursion of saline waters deep into the river channel during the dry season facilitates aggregation and settling of particulate-borne pollutants close to the discharge area, thereby keeping the estuarine waters free from major contamination.

Impact of Past Iron Ore Mining on the Sediment Cores of Rivers of Goa. West-coast of India

“…The moderate pollution of Fe and Mn in sediment cores is directly related to Fe-Mn ore deposits and humaninduced activity in handling and transportation of these ores through the river. Shynu et al (2012) and Alagarsamy (2006) also observed a high value of Fe and Mn in suspended matter and surface sediments, respectively in the Mandovi river. The moderate contamination of Cu and Cr might be associated with the presence of boatyard and small vessel building yards.…”

Effect of tropical rainfall in structuring the macrobenthic community of Mandovi estuary, west coast of India

“…Monthly rainfall data and total sunshine was obtained from the Meteorological Station, Goa. Temperature, salinity and chlorophyll- a (Chl a ) data were obtained from the Data Centre of National Institute of Oceanography (CSIR), Goa, while total suspended solid (TSS) data is from Shynu et al (2012).…”

Assessment of metal enrichment and their bioavailability in sediment and bioaccumulation by mangrove plant pneumatophores in a tropical (Zuari) estuary, west coast of India

“…Around 15 million t of iron and manganese ore was transported annually along these rivers to the nearby Mormugao harbor in 1990′s (Satyanarayana and Sen Gupta, 1996) which increased to around 50 million t in 2010′s. The ore stored for transportation at different points on the shores of the estuary gets eroded and flushed into the estuaries during heavy monsoon rains and part of the ore and/or dust ultimately gets accumulated in the estuaries and is incorporated into sediment (Shynu et al, 2012;Alagarsamy, 2006. Iron ore was mined from the banded iron formations of Goa, India, and transported through the Mandovi and Zuari estuaries for six decades until the ban on mining from September 2012.…”