Concentrations and annual loading of dissolved organic matter in a small moorland stream

SUMMARY. 1. Dissolved organic matter (DOM) was measured at 8h intervals over a 1 year period in a stream draining 51 ha of moorland with peaty soils. 2. DOM concentrations increased with increasing stream discharge from low flow values of 0–3 mg 1 −1 to maximum values of 30 mg 1 −1 . There were also seasonal differences of up to 13mgl −1 between August (maximum) and February, and differences of about 2.5 mg l −1 between rising and falling stage samples. 3. Seasonal variation was closely related to mean temperature. 4. Total loss over the year was 168 kg ha −1 DOM (84 kg ha −1 C), larger than previous estimates for upland sites.