Are temporal variations in the nitrate content of UK upland freshwaters linked to the North Atlantic Oscillation

Synchron ous patterns of variation in NO3 concentration, observed in upland lakes and streams across gradients of climate, altitude, land use and nitrogen deposition over the last decade, show a strong negative correlation with winter values for the North Atlantic Oscillation Index and mean winter temperature. Variations in a longer term stream NO3 record validate this relationship, and although mechanisms are yet unclear, may be linked to the length of time the soil profile remains frozen during the winter. These findings are of particular significance to our understanding of the relationship between atmospheric N deposition and concentrations and fluxes of NO3 in runoff, and the potential response to future climatic changes. Copyright (C) 2000 John Wiley and Sons, Ltd.

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