HIGH ATMOSPHERIC NITROGEN DEPOSITION EVENTS OVER THE NORTH-SEA

Atmospheric circulation patterns over the North Sea occasionally resul t in episodes of high concentrations of various contaminants. Synergis tic chemical effects can act to enhance the deposition of nitrogen dur ing these events resulting in highly episodic nitrogen inputs to the N orth Sea. Two such episodes are described and their causes interpreted . The problems of devising sampling strategies to quantify these event s and assess their effects on phytoplankton communities are discussed.