Nutrient transformations between rainfall and stormwater runoff
in an urbanized coastal environment: Sarasota Bay, Florida
Dillon, Kevin S., Jeffrey P. Chanton  Limnol. Oceanogr., 50(1),
2005, 62-69 | DOI: 10.4319/lo.2005.50.1.0062  ABSTRACT: To
determine the relative importance of atmospheric deposition and
stormwater runoff as nitrogen sources to Sarasota Bay, Florida,
we examined dissolved inorganic nitrogen (DIN) concentrations
and d15N compositions of rainwater and stormwater runoff.
Rainwater collected in Sarasota, Florida, had ammonium
concentrations of 2.1- 29.0 µmol L-1 in the summers of 1999 and
2000. Corresponding rainwater nitrate concentrations were
3.7-56.0 µmol L-1. Rainwater ammonium δ15N values were -11.6‰ to
-0.3‰, and nitrate δ15N values were -5.1 to +3.8 over the 2-yr
period. Decreases on the order of 50% in ammonium concentration
and δ15N enrichments as great as 124‰ relative to rainwater
ammonium were typically observed in the evolution of rainwater
into stormwater. Stormwater δ15NH4 va