Heavy metal concentration in seawater and sediment of Gulf of Mannar and Palk Bay, southeast coast of India

Abstract

<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">An investigation was carried out to delineate the levels of heavy metals both in the seawater and sediments from the Gulf of Mannar and Palk Bay. The data, obtained during the year 1995 revealed that Cd could not be detected in the waters of Kanyakumari. However, at other stations the levels of Cd were in the order of Arumuganeri > Tuticorin > Thondi > Mandapam . In contrast, Pb levels were found to be maximum at Kanyakumari and minimum at Arumuganeri, while Hg was found to be maximum at Arumuganeri and minimum at Mandapam. Cd levels were found to <span style="font-size:14.0pt;line-height:115%;font-family:" times="" new="" roman";="" mso-fareast-font-family:hiddenhorzocr;color:black;mso-ansi-language:en-in;="" mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">decrease <span style="font-size:14.0pt;line-height:115%;font-family:" times="" new="" roman";="" mso-fareast-font-family:"times="" roman";color:black;mso-ansi-language:en-in;="" mso-fareast-language:en-in;mso-bidi-language:hi"="" lang="EN-IN">towards sea from the coast at Tuticorin. However no definite trend was observed at Mandapam and Thondi. Unlike Cd, Pb showed seaward increasing trend at Thondi transect. However, no definite trend was evident for other transects as seen for Cd. Bottom waters showed higher concentration of Cd and Pb as compared to those in surface water. Hg did not show any trend in its distribution. Data on sediments showed that Cd registered maximum levels at Arumuganeri (4.33 ppm) while Kanyakumari exhibited the minimum (0.4 ppm). Similarly the levels of Pb were found to be minimum (1.15 ppm) at Kanyakumari . In conclusion, among the transects studied, Arumuganeri appeared to be <span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:hiddenhorzocr;="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">polluted.</span></span></span></span>