Effects of Ditch Network Maintenance on the Chemistry of Run-off Water from Peatland Forests

Ditch run-off chemistry of 40 catchments was monitored before and for 2-3 yrs after maintenance of the peatland ditch network and compared with data collected from 34 control catchments. Increases in mean pH, electrical conductivity, and the concentrations of suspended solids and base cations (sodium, potassium, calcium and magnesium) and a decrease in the concentration of dissolved organic carbon were observed. Because of high concentrations in a few areas immediately after the digging operations and during the first post-treatment year in general, the mean concentrations of aluminium and iron also increased. No major changes occurred in the concentrations of total dissolved nitrogen (N) and total dissolved phosphorus. High phosphorus concentrations were observed at a few sites immediately after the digging operations. Concentrations of mineral N, especially NH+ 4-N, increased significantly, while the concentrations of organic N decreased. The largest relative changes in element transport during the 3 yr period following treatment were the increases in the loads of NH+ 4-N and suspended solids. From the point of view of water protection, the loading of suspended solids was considered the most harmful effect of ditch network maintenance.