Saturation of raised bog peat exchange sites by Pb 2+ and Al 3+ stimulates CH 4 production

Abstract

We examined the effect of cation treatments on methanogenic activity and nutrient release from exchange sites in raised bog and fen peats. Treatments consisted of cation chloride solutions (MgCl 2, AlCl 3 and PbCl 2) applied individually. In raised bog peat Al 3+ and Pb 2+ increased CH 4 production. A correlation was found between CH 4 production and the amount of micro- and macronutrient cations released by the treatments. In calcareous fen peat, such a stimulation was also found, but there was no correlation between CH 4 production and micro and macronutrient release. Direct nutrient and pH effects could not account for these observations. Thus the results support the hypothesis that the methanogenic community in the raised bog is limited by the availability of mineral nutrients and/or inactivity of exo-enzymes, both of which are bound onto exchange sites.