Determination of Atmospheric Nitrogen Input to Lake Greenwood, South Carolina: Part 2. Gaseous Measurements and Modeling

Andrew S. Imboden, Lynn G. Salmon, and Christos S. Christoforou
Journal of the Air and Waste Management Association 53 (2003) 1499-1508


The Reedy River branch of Lake Greenwood, SC, has repeatedly experienced summertime algal blooms, upsetting the natural system. A series of experiments were carried out to investigate atmospheric nitrogen (N) input into the lake. N was examined because of the insignificant phosphorus dry atmospheric flux and the unique nutrient demands of the dominant algae (Pithophora oedogonia) contributing to the blooms. Episodic atmospheric measurements during January and March 2001 have shown that the dry N flux onto the lake ranged from 0.9 to 17.4 kg N/ha-yr, and on oaverage is caused by nitric acid (HNO3; 31%), followed by nitrogen dioxide (NO2; 23%), fine ammonium (NH4+; 20%), coarse nitrate (NO3-; 16%) fine NO3- (5%), and coarse NH4+ (5%). Similar measurements in Greenville, SC (the upper watershed of the Reedy River), showed that the dry N deposition flux there ranged from 1.4 to 9.7 kg N/ha-yr and was mostly caused by gaseous deposition (40% NO2 and 40% HNO3). The magnitude of the dry N deposition flux is comparable to wet N flux as well as other point sources in the area. Thermodynamic modeling showed low concentrations of ammonia, relative to the particulate NH4+ concentrations.

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