Determination of atmospheric nitrogen input to Lake Greenwood, South Carolina http://trophort.com/research/004/100/... Lake Greenwood experiences summertime algal blooms, upsetting the natural ecosystem. The unique nitrogen demands of the dominant algae (Pithophora oedogonia) makes this the main species contributing to the algal blooms. The predominant form of the N deposition flux is in ammonium (NH4) form at an annual magnitude of 0.9 to 17.4 kg N/ha.