Distribution of Heavy Metals in the Brown Alga, Ascophyllum nodosum along the fjords of the Trondheim Region, Norway

Abstract

A regional heavy-metal survey of the Trondheim (1:500 000) map sheet was carried out using seaweed as a sample medium. No values elevated above that explainable as regional background were observed for ash, Mo,Pb,Hg or As. Analyses were also performed for Ca,Na,and F but are not reported here. Significant variations in Zn,V,Cd,Co,Cu.Mn, and Fe were observed; elevated values usually being associated with the mouths of the major river systems suggesting an excess of these elements is being supplied by fresh water. Elevated values of Ni and V show an areal distribution dependent on the rock substrate while very high values of Zn od Cu appear to be derived from mine wastes along the Orkla river. No individual element seems to be diagnostic of incoming sea water. Recommendations are made for follow-up surveys of Ag and V in Halsafjord, V in Aafjorden, and U on Hitra. Although the initial impetus for this survey was for prospecting the region for metallic ore deposit, it would appear that, because of extensive mining in the past, the method is better suited for monitoring heavy-metal contamination, establishing regional backgrounds, and defining chemically distinct water masses within fjord systems.