Regional distribution of manganese, phosphorus, heavy metals, barium and carbon in sea-bed sediments (0-2 cm) from the northern part of the Norwegian Skagerrak

Abstract

The regional distribution of manganese, phosphorus, heavy metals, barium and organic carbon in sea-bed sediments (0-2cm) from the northern part of the Norwegian Skagerrak has been mapped and the results discussed in the light of dispersion processes from natural and human sources. Similar distribution patterns are found for manganese (Mn), phosphorus (P) and the heavy metals Cr, Cu, Ni, Pb, V and Zn which all intercorrelate well. The highest levels of these elements occur in the deepest parts of the Skagerrak Basin. Barium (Ba) is concentrated at stations located in the shallower waters in the southern part of the investigated area. Mercury (Hg), on the contrary, has a bimodal distribution, being enriched in the northermost area and along the Norwegian south coast. The highest concentrations of total carbon and organic carbon are found at intermediate water depths around the perimeter of the deep Skagerrak Basin. According to the State Pollution Authority's (Statens Forurensningstilsyn 1993) classification of the condition of sediments based on concentrations of heavy metals (Category I= Good, II= Fair, III= Poor, IV= Bad, V= Very bad), the sea-bed sediments in the northern part of the Norwegian Skagerrak fall in Category II with respect to Ni and Pb and in Category I with respect to Cr, Cu and Zn.