Accumulation rates and mass calculations of Zn and Hg in recent sediments, Göta älv estuary, Sweden

Abstract

Sediment masses and heavy-metal accumulation rates for the recent deposits of the Gota alv estuary were calculated using a GIS. Total masses of 4,000 t Zn and >20 t Hg were recorded, of which 367 t Zn and >0.72 t Hg occur in the inner estuary, the Goteborg harbour, and 3,657 t Zn and 19 t Hg are in the outer estuary, suggesting a high trapping efficiency of the estuary. The accumulation rates are 5 g m–2 year–1 Zn and 0.01 g m–2 year–1 Hg in the harbour, and 1.5 g m–2/year–1 Zn and 0.007 g m–2 year–1 Hg in the outer estuary. The Zn and Hg accumulation rates are highest close to the outlet of a sewage treatment plant, and decrease by a factor of 5 for Zn, and a factor of 2 for Hg in the outer estuary. The accumulation rates in the outer estuary decrease after 1980 A.D.