Two subarctic fens (one nutrient-poor, one nutrient-rich) were sampled from October, 1984 to July, 1985 near Schefferville, northern Quebec. The changes in concentations of chemicals (pH, conductance, Ca, Mg, Na, K, Fe, dissolved organic carbon, P, NH4+-N and N03-N) dissolved in the peat water were identified during the freeze-thaw cycle. The highest chemical concentrations were in the winter (associated with the ice formation process), followed by the spring-summer, then fall. Four main processes influenced the concentration of dissolved chemicals in subarctic fens: 1) Snowmelt diluted the peat water; 2) Freezing of the peat increased concentrations of dissolved nutrients and other chemicals, believed to originate from biological sources; 3) Further increases in concentrations over the winter were caused by the incorporation of peat water, which migrated into the frozen peat; 4) Thawing of peat influenced the water chemistry by combining the release of the above 3 processes, along with biotic utilization. The freeze-thaw cycle in the subarctic fens appeared to increase the availability of important nutrients (such as phosphorus) during the spring.

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