Rainfall concentrations and wet atmospheric deposition of phosphorus and other constituents in Florida, USA

Concentrations of phosphorus (P) and other constituents in weekly composited rain samples and concurrently acquired rainfall volumes, collected from September 1992 through October 1993, were used to estimate volume-weighted concentrations and wet atmospheric deposition rates, and compared to estimates from previous studies. Since this study's purpose was to estimate regionally representative concentrations and rates of wet atmospheric deposition, sampling locations were chosen to avoid sites characterized by substantial local resuspension or recycling phenomena. Significant differences were found in the wet deposition rates of calcium (Ca), magnesium (Mg), potassium (K), sodium (Na), hydrogen (H), and chloride (Cl) ions between sampling stations in Florida. Consequently, statewide deposition rates and volume-weighted concentrations were estimated only for P, and for orthophosphate (PO(4)), ammonium (NH(4)), nitrate (NO(3)) and sulfate (SO(4)) ions that were not found to be spatially variable. Over the period of record, the mean rate of wet atmospheric P deposition across the state, and the mean rainfall P concentration, were found to be 25+/->5 mug P M(-2) wk(-1) and 1.3+/-0.1 mug P L (-1), respectively.