Evidence for Microbial Community Effect on Sediment Equilibrium Phosphorus Concentration (EPC₀)

Batch equilibrium phosphorus concentration (EPC₀) methods were applied to determine phosphorus capacity of sediments from three agriculturally influenced tributaries in southern Ontario - Belle River, Big Creek, and Nissouri Creek. Aliquots of sediments were amended with soluble reactive phosphorus and incubated at four temperatures (5, 15, 25, and 35°C). Batches of sediments from each location and temperature were also subjected to a treatment; gamma (γ)-irradiated at 28 kGy over 24-h (sterilized) and compared to non-sterilized biotic samples. Treatment showed a significant effect on EPC₀ in Belle River and Nissouri Creek but non-significant effect in Big Creek. Temperature showed a significant effect in Belle River, Nissouri Creek, and the biotic subset of Big Creek. While direction of shift was not consistent in all cases, the biotic subsets of all three locations showed a significant effect of temperature.