Trace metals anthropogenic change

A differentiation between natural and anthropogenic heavy metal loads into the Baltic is not possible because metals are also natural components of the earth s crust. Taking into consideration that the HELCOM database is stiU incomplete, a general reduction of the total metal load was calculated for Hg ( 74%), Pb (< 66%), Cd ( 62%), and Zn ( 9%) between 1990 and 1995. For Cu, an increase of 13% was estimated. With the addition of the trace metal input data from the fourth pollution load compilation, the situation changed drastically. Compared to 1995 (HELCOM, 1998), the total heavy metal loads increased by a factor of -3 for Cd, 4 for Pb, and 9 for Hg in 2000 (HELCOM, 2004,2005), while for Cu (0.7) and Zn (0.8) a decrease of the river loads was estimated. The heavy metal export into the North Sea is of circumstantial relevance in relation to the total metal load entering the Baltic Sea (Dippner and Pohl, 2004). 

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