Assessment of metal enrichment and contamination in surface sediment of Mandovi estuary, Goa, West coast of India.

Metal concentration in the sediments was determined to assess the metal enrichment and level of contamination in the Mandovi estuary. The metal distribution in the Mandovi estuary revealed preferential input through open-cast iron-ore mining, industrial, fishing, and agricultural activities. The heavy riverine runoff associated with high rainfall influenced the distribution of Mn, Zn, and Pb during monsoon season. In addition, sediment grain size and associated organic matter governed metal distribution in surface sediments. The role of grain size and organic matter along with Fe-Mn oxides in the distribution of metals was construed through correlation and factor analysis. Geo-accumulation index, contamination factor, and potential contamination index indicated contamination of surficial sediments of the Mandovi estuary with Cr and Pb.

Assessment of crustal element and trace metal concentrations in atmospheric particulate matter over a coastal city in the Eastern Arabian Sea.

Major/crustal elements (Al, Ca, Mg, K, and Fe) and trace metals (Mn, Cr, Cu, Pb, Zn, and Ni) in atmospheric particulate matter at three sites in Goa (a coastal city in the Eastern Arabian Sea) were assessed during winter (December) and summer (March-May) months of 2015. A significant spatial and temporal variability was observed in PM10 mass concentration, crustal element, and trace metal composition at the sampling area (pristine, urban, and industrial locations). Using a diagnostic crustal element ratio (Fe/Al, Ca/Al, and Mg/Al), mineral dust components were characterized and found to show large spatial and temporal variability. The concentration levels of trace metals were further assessed for enrichment factor (EF) analysis, wherein reported elements were classified into two major groups. The first group consists of Cr, Cu, and Pb with 10< EF < 100 compared to continental crustal values (w.r.t. Al), suggesting a dominant contribution from anthropogenic sources with minor contribution from natural sources; the second group consists of Zn and Ni showing very high EF (>100)-these are solely derived from anthropogenic sources. Source identification for trace metals was further assessed based on principle component analysis (PCA). PCA highlights that the major contribution of trace metals is from anthropogenic emissions at all three locations. However, contributions from mineral dust were observed at pristine and urban locations during winter months. The reported data of trace metal concentrations in aerosols give baseline information on the atmospheric supply of micronutrients to the Arabian Sea, which has implications for the various surface ocean biogeochemical processes.Implications: This paper reports on crustal and trace metal composition and concentration level in atmospheric aerosols over a coastal city located on the Eastern Arabian Sea. This study highlights the role of various factors (meteorology and emission sources) controlling the abundance of metals over a coastal site. The contribution from various sources (anthropogenic vis-à-vis natural) has also been identified using enrichment factor analysis as well as principle component analysis. This study has implications for the supply of micronutrients to the coastal Arabian Sea, which can significantly impact various surface ocean biogeochemical processes.

Impact of mining on metal concentration in waters of the Zuari estuary, India.

The rationale of the current study was to establish that mining and associated activities are the chief sources of trace metal contamination in the Zuari estuary, Goa. Surface and bottom water samples were collected monthly, at 11 stations, starting from the mouth of the estuary, covering a stretch of 35 km towards the head during the period of ban on mining in Goa as per the directions of the Honourable Supreme Court of India. The water samples were analysed for physicochemical parameters and metals (Fe, Mn, Zn, Cr, Cu and Pb). Spatial variation of metals (Zn, Cr and Cu) indicated high concentrations at the mouth region, revealing that they are derived by resuspension of bottom sediments at higher salinities, while metals Fe, Mn and Pb showed higher concentrations at the head region, indicating that these are derived from freshwater discharge. Seasonal variation of metals revealing high concentrations during non-monsoonal months was attributed to a high rate of evaporation and intense anthropogenic activities except Pb. Contamination factors and enrichment factors of metals were calculated to assess the degree of metal contamination and relative abundance of pollutants, respectively. Sources of metals into the estuary were discussed by using principal component analysis. Correlation coefficients were calculated to find out the dynamics among the physicochemical factors and trace metals. The study exemplified that concentrations of trace metals in waters of the Zuari estuary were significantly less when compared to the periods of rampant mining activity around Goa, indicating that mining can influence the concentration of metals in the Zuari estuary.