A heavy metal monitoring-programme in Denmark

A monitoring programme for the concentrations of heavy metals in Danish arable soils and on nature areas was initiated in 1990 by the Danish EPA. The monitoring programme comprises 393 sampling points scattered in a regular grid over the country and in addition 20 sampling points on agricultural fields fertilised with sewage sludge. Samples taken from the top 25 cm of the soil at each sampling point have been analysed for the heavy metals Pb, Cd, Cu, Cr, Hg, Ni and Zn and for the metalloid As. The content of Ni, Zn and Cr and to some extent Cu and As, are well correlated with soil texture. Differences are not found between soils with different land use, atmospheric deposition, etc. that renders it possible, that the soil content of heavy metals in general is determined by anthropogenic sources. It is, however, possible, that the concentrations at some points with high values of As, Cd, Cu, Pb and Hg are affected by anthropogenic sources. The measured concentrations are comparable to what have been found in earlier Danish investigations and typically lower than levels found in neighbouring countries. It is concluded that the levels of heavy metals found in Danish arable soils and on nature areas in general do not give rise to concern. The levels are generally low compared to Danish soil quality criteria and the current load is modest compared to the content in the soil.