Geochemical baselines
Sampling year: 2002
Sample media: humus: concentrated nitric acid extraction from the <2 mm grain-size fraction; topsoil (0–25 cm) and subsoil: total concentrations, aqua regia extractable concentrations and acid ammonium acetate extractable concentrations from the <2 mm grain-size fraction
Soil parent materials: sand 30 profiles, glacial till 50 profiles, clay 50 profiles
The Geological Survey of Finland (GTK) has studied geochemical baseline concentrations in the Porvoo region using topsoil, subsoil and humus samples collected in 2002. Altogether, 130 sample profiles represented the most common mineral soil types of the region. Aqua regia extraction was used for mineral soil samples and concentrated nitric acid for humus samples. In addition to aqua regia extractable concentrations, total concentrations and concentrations extracted by acid ammonium acetate leach were also determined from mineral soil samples. All the analysis were performed on the <2 mm grain–size fraction.
A good correlation was recorded between topsoil and subsoil concentrations, suggesting a geological origin for the distribution patterns. Concentrations of most trace elements, including heavy metals, were highest in fine-grained (clay) soil deposits. The organic matter content in minerogenic topsoil showed good a correlation with Hg, Pb and Cd, partly reflecting atmospheric deposition and other anthropogenic input.
Report:
Tarvainen, T., Hatakka, T., Kumpulainen, S., Tanskanen, H., Ojalainen, J. & Kahelin, H. 2003. Alkuaineiden taustapitoisuudet eri maalajeissa Porvoon ympäristössä. Geologian tutkimuskeskus, arkistoraportti S/41/3021/2003/1. 56 s. 1 liite. http://tupa.gtk.fi/raportti/arkisto/s41_3021_2003_1.pdf
Statistics:
