Heavy metal studies of core sediments, Ashtamudi estuary, Southern Kerala, India.

The investigation carried out on metals concentration in Ashtamudi estuarine core sediments reveals that, the pollution load index values in core 1 (AS 05) at mouth of estuary ranging from 1.56 to 1.95 with an average value of 1.72 and in core 3 (AS 17) at southern Kayal from 1.62 to 2.07; with an average 1.92 and in core 2 (AS 16) at central Kayal it ranged from 1.91 to 3.07 with higher average value of 2.33, which indicates that core 2 sediments are highly contaminated compare to that the core sediments core 1 and 3. The average enrichment factors of Cr 4.31; 3.47; 4.21 in core1, 2 and 3 respectively, Ni, 3.92; 3.49; 3.42 in core 1, 2 and 3 respectively and Cu 3.23 in core 2 are >2, suggesting contamination of these metals in the Ashtamudi estuary sediments. The adverse effect of the metals in the core sediments indicates that Ni concentration is recorded higher than the ERM values in all the three core sediments, Cu concentrations in core 2 and Cr concentrations in core 3, are potentially of concern, as they are between ERL and ERM with an effect of 93%, 87% and 83% respectively. Cu in core 1 and 3, Cr in 1 and 3 and Zn in core 2 and 3 concentration are recorded lower than the ERL value, whereas Pb concentration in core 1 shows that 13% of samples are recorded lower than the effects range