Geochemical controls on peatland pore water from the Hudson Bay Lowland: A multivariate statistical approach

Pore-water samples were collected in the Albany River drainage basin of the Hudson Bay Lowland. The chemistry of these samples was evaluated using bivariate plots, cluster analysis, and principal component analysis to determine the importance of groundwater and to evaluate geochemical processes within the peat. The transport of dissolved constituents from the mineral soil into the peat column is a dominant control on peat pore-water chemistry. Peatland land-forms have different signatures for pore-water chemistry; bogs are characterized by elevated concentrations of dissolved organic carbon, CH₄, SiO₂, K⁺ and larger mineral ion balance errors, whereas fens are characterized by their higher pH and alkalinity. Large mineral ion balance errors (up to 99%), the inverse relationship between pH and dissolved organic carbon, and the positive correlation between mineral ion balance error and dissolved organic carbon show that organic acids are important anions in bog pore waters. Methane concentrations and SO₄^2- concentration are inversely related, suggesting that SO₄^2- inhibits CH₄ production. Peat pore water at several locations contains high concentrations of marine salts (SO₄^2-, Cl^-, and Na⁺) in the lower half of the peat column, indicating that the marine sediments contain sea salts. We suggest that SO₄^2- from these marine sediments may reduce methane production in portions of the Hudson Bay Lowland.