Modelling nitrogen dynamics at Lochnagar, N.E. Scotland.

摘要

Controls on nitrate leaching from uplandmoorland catchments are not yet fully understood and yet, despite agreements onemission reductions, increased surface water nitrateconcentrations may affect significantly the acidity status of these waters inthe future. At Lochnagar, an upland moorland catchment inN.E. Scotland, 12 years of surface water chemistry observations have identifieda steady increase in nitrate concentration despite nomeasured change in inorganic nitrogen deposition. The MAGIC model has beenapplied to simulate a "best case" situation assumingnitrate in surface water represents "hydrological" contributions (directrun-off) and a ‘worst case’ assuming a nitrogen saturationmechanism in the catchment soil. Only the ‘saturation’ model is capable ofmatching the 12 years of observation for nitrate but bothmodel structures match the pH and acid neutralising capacity record. Futurepredictions to 2040, in response to the agreed emission reductionsunder the Gothenburg Protocol, are markedly different. The worst case predictscontinued surface water acidification whilst the best casepredicts a steady recovery. style="line-height: 20px;">Keywords: nitrogen saturation, modelling, Lochnagar, Gothenburg Protocol