Epsilon Archive for Student Projects

Abstract

Soils in a metal contaminated site on Stångberget in Gusum in southeast
Sweden were investigated and compared to relatively unaffected soils a few
kilometres away. Pollution came from historical release of untreated flue gases
from a brass mill. The objective was to find information on how high the metal
concentrations are, if metals from the polluted soil affect the surroundings and
if the metal contamination affects the microbial community. The soil was
investigated using several different methods, such as field XRF measurements,
chemical analysis of metal, carbon and nitrogen content, pH, acid neutralizing
capacity, texture, soil depth, field leach tests, sequential extraction and microbial
functional profiles. The study showed that copper and zinc concentrations
were above Swedish Environmental Protection Agency guidelines for less
sensitive land use on the entire investigated area. Copper showed the highest
concentrations in relation to guideline values, 50 times the guideline in the
worst affected sample point, followed by zinc, lead and cadmium, in that
order. A pH raising effect caused by the release of metal oxides, that had
previously been shown could not be seen and pH on Stångberget was now
similar to that of a natural Swedish forest soil. Results could not show that the
pH drop had caused increased leachability, instead the leachability was lower
than in previous studies. Leaching from Stångberget did not seem to affect
metal concentrations in the soil nor be a major source of metals to surrounding
soils and waters. Microorganisms from the visibly affected part of Stångberget
had an increased specific respiration compared to the reference but the difference
between the forested part of Stångberget and the reference area was not
as clear even though metal concentrations were severely elevated also in the
forested part. The effect on microorganisms could to a large extent be explained
by the metal contamination. The size of the bare part of Stångberget
had increased over the last 50 years and there was no sign of a decrease.