Predicting the future DOC flux from upland peat catchments

This study reconstructs a long-term record of dissolved organic carbon (DOC) flux release from an upland peat catchment in Northern England in order to construct a model of future DOC flux. A structural modelling approach is used to develop models for DOC production in the acrotelm in relation to changing temperature and water table depth. DOC production in the acrotelm is coupled with a description of release of reserves of carbon from the catotelm triggered by enzymic latch mechanisms. The model needs only three parameters to be successfully matched to the data, with Nash-Sutcliffe efficiencies of over 90% against the reconstructed catchment record. Model results suggests that the half-life of the effect of drought on the catchment is 11.2 years and that the majority of DOC production comes from the acrotelm/catotelm boundary. Using the calibrated model and predictions of future rainfall and temperature, it is forecast that DOC flux from this peat-covered catchment will increase to 25 tonnes C/km2 by 2010 at a rate of 0.48–0.88 tonnes C/km2/year. These results imply a total DOC flux from UK rivers of 0.88–0.83 Mt C in 2002 and of the order of 1 Mt C by 2010. The implications for terrestrial carbon storage and water treatment are discussed.