The interaction between decomposition, net N and P mineralization and their mobilization to the surface water in fens

• Published in: Water research (Oxford) 2010-06, Vol.44 (11), p.3487-3495
• Main Authors: Geurts, Jeroen J.M., Smolders, Alfons J.P., Banach, Artur M., van de Graaf, Jan P.M., Roelofs, Jan G.M., Lamers, Leon P.M.
• Format: Article
• Language: English
• Subjects: aerobic conditions; anaerobic conditions; Applied sciences; Carbon - analysis; Carbon - chemistry; carbon nitrogen ratio; Continental surface waters; Decomposition; Exact sciences and technology; fen soils; Fens; Fluxes; Fresh Water - chemistry; Geologic Sediments - chemistry; Iron; Kinetics; Lakes; Mineralization; Natural water pollution; Nitrogen; Nitrogen - analysis; Nitrogen - chemistry; Nutrients; organic matter; Other industrial wastes. Sewage sludge; Peat; Phosphate; Phosphates - analysis; Phosphates - chemistry; Phosphorus - analysis; Phosphorus - chemistry; Pollution; Porosity; Sediments; Soil - analysis; Soil Pollutants - analysis; Soil Pollutants - chemistry; Sulphate; surface water; Wastes; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - chemistry; Water treatment and pollution; Wetlands
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2010.03.030

Worldwide, fens and peat lakes that used to be peat-forming systems have become a significant source of C, N and P due to increased peat decomposition. To test the hypothesis that net nutrient mineralization rates may be uncoupled from decomposition rates, we investigated decomposition and net mineralization rates of nutrients in relation to sediment and pore water characteristics. We incubated 28 non-calcareous peat sediments and floating fen soils under aerobic and anaerobic conditions. We also tried to find a simple indicator to estimate the potential nutrient mobilization rates from peat sediments to the water layer by studying their relation with sediment and pore water characteristics in 44 Dutch non-calcareous peat lakes and ditches. Decomposition rates were primarily determined by the organic matter content, and were higher under aerobic conditions. However, highly decomposed peat sediments with low C:P and C:N ratios still showed high net nutrient mineralization rates. At Fe:PO 4 ratios below 1 mol mol −1, PO 4 mobilization from the sediment to the water layer was considerable and linearly related to the pore water PO 4 concentration. At higher ratios, there was a strong linear correlation between the Fe:PO 4 ratio and PO 4 mobilization. Hence, measuring Fe and PO 4 in anaerobic sediment pore water provides a powerful tool for a quick assessment of internal PO 4 fluxes. Mobilization of mineral N was largely determined by diffusion. Total sediment Fe:S ratios gave an important indication of the amount of Fe that is available to immobilize PO 4. Pore water Fe concentrations decreased at ratios