%0 Journal Article
%T Chemical properties of surface peat on forest land in Estonia
%A R. Kˋlli
%A E. Asi
%A V. Apuhtin
%A K. Kauer
%J Mires and Peat
%D 2010
%I 
%X The chemical properties of surface peat cover (SPC) were studied in the context of Estonian pedoecological conditions. SPC comprises the superficial layers of fens (Group 1) and transitional bogs (Group 2), together with slightly acid peaty mull / strongly acid peaty moder (Group 3) and very strongly acid peaty mor (Group 4) layers overlying mineral soils. Thus, it spans organic soils, namely Histosols (Groups 1 and 2); together with Histic Gleysols (Group 3) and Histic Podzols (Group 4), which are developmentally intermediate between organic and mineral soils. Moderately acid eutrophic (Group 1) and very strongly acid mesotrophic (Group 2) peats (forest litter layers excluded) were uniformly characterised up to 40 cm depth; whereas for Groups 3 and 4 we examined the full thickness of available peat layers, which ranged from 10 to 30 cm. The results show that Al, K and heavy metal contents are significantly higher and organic carbon content is lower in Histic Soils (3, 4) than in Histosols (1, 2). The amounts of Ca, Mg, Mn and Fe are significantly higher and C:N ratio, exchangeable acidity and content of free H+ lower in less acidic (1, 3) than in more acidic (2, 4) soil types. The total concentration of elements (excluding heavy metals) extracted by nitro-hydrochloric acid (aqua regia) is considerably higher in less acidic soils, at 28每45 g kg-1 (1, 3) versus 10每12 g kg-1 (2, 4); and mean contents of individual elements decrease in the order Ca(51%) > Fe(20%) > S(10%) ≡ Al(10%) > Mg(3%) ≡ P(3%) > K(2%) > Mn(1%) > Na(<1%). The most abundant heavy metals are Pb (12每33 mg kg-1), Zn (7每41 mg kg-1), Cu (3每12 mg kg-1), Cr (2每23 mg kg-1) and Ni (2每8 mg kg-1); Cd and Hg contents are very low, ranging from 0.2 to 0.5 mg kg-1. The dominant exchangeable basic cations are Ca2+ (78每93%) and Mg2+ (7每15%), and the peat contains much smaller amounts of K+ (1每6%) and Na+ (<2%). The total exchangeable acidic cations (1每14 cmol kg-1) are dominated by H+ (51每83%) and Al3+ (15每47%), whereas Mn and Fe (2每4%) cations are modestly represented.
%K exchangeable cations
%K heavy metals
%K Histic Gleysols
%K Histic Podzols
%K Histosols
%U http://www.mires-and-peat.net/map06/map_06_06.pdf