Salt inhibition of methanotrophic activity in sphagnum peat

The influence of mineral and organic fertilizers on the methanotrophic activity of sphagnum peat from Bakcharskoe (Western Siberia, Tomsk oblast) and Kurovskoe (Moscow oblast) bogs was studied. The addition of different salts (48 kinds of mineral and organic compounds) at a concentration of 1-10 mmol/kg of moist peat mass reduced the methanotrophic activity, which is differently related to the properties of cations and anions. Iodides, bromides, chlorides, and nitrates exerted the maximal inhibiting effect; sulfates and carbonates exerted little effect. The degree of inhibition by Na and K halides increased in the following sequence: Cl < Br < 1. Among the chlorides, Al, Ba, and Sr chlorides lowered the methanotrophic activity to the greatest degree; K and Na chlorides lowered the methanotrophic activity the least. The Mg and Ca chlorides occupied an intermediate position with respect to their effects on the methanotrophic activity. The degree of inhibition of the methane oxidation by salts correlated (r = 0.8-0.9, p < 0.05) with the numbers of the elements in Mendeleev's periodic system. The degree of inhibiting the methanotrophic activity was lower in the peat from the Moscow oblast bog as compared to the Western Siberian bog, probably due to the long-term adaptation to the higher background pollution.