Fjölrit RALA - 15.06.2004, Blaðsíða 122

concentrations of Zn, As Ni and Cr all correlated closely with Fe and A1 levels hence it may
be assumed that these elements have come from geochemical sources. Pb, Cd and Cu showed
close correlation for most of the data but the outliers could be related to localized
anthropogenic sources either through land-use or nearby domestic, industrial or infrastructural
activities.
The relationship for the vegetation was quite different than for the soils. For Pb and Cu the
metal levels in the plant rose with the Fe associated fraction. The converse observation was
made for the other elements. In particular Cd and Ni had a dose response relationship.
Metal accumulation in the vegetation closely correlated with the metal levels in the soil.
The relationship, however, was better explained by introducing other soil parameters
including SOM, pH and soil texture. An estimation of likely metal assimilation was made
and could be related both to the plant dry matter and the plant species.
Despite the relatively elevated metal loadings in the soil, there was little evidence to suggest
that the elements were posing an acutely toxic effect. There was a degree of correlation
between the sensor responses and the assimilation into plants though the ouliers could be
explained by means of the source of the contaminants.
Conclusions
Most of the elevated levels of metals in the soils of Iceland can be explained by the presence
of volcanic deposition in the pedosphere. Some metals and metalloids are associated with
anthropogenic sources and these are visible as outliers in the correlations. Plant assimilation
is related to the soil metal loadings. Although elevated, the metals and metalloids appear to
have little acute toxicity.
References
Flynn HC, Meharg AA, Bowyer PK, Paton GI. 2003. Antimony bioavailability in mine soils.
Environmental Pollution 124, 93-100.
Tiensing, T., Preston, S., Strachan, N., Paton, GI. 2001. Soil solution extraction techniques for
microbial ecotoxicity testing: a comparative evaluation. Joumal of Environmental
Monitoring 3, 91-96.
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