Spray water volume and chemistry from the Ice Storm Experiment (ISE) at the Hubbard Brook Experimental Forest

The volume of water applied per plot was calculated as the product of application time and water flow (302.8 L/min). Two hoses sprayed water simultaneously and we estimated that 90% of the spray was applied inside the plot. To construct chemical budgets for the treatments, a 60 ml aliquot of Hubbard Brook stream water was collected prior to each icing, and analyzed for sulfate (SO4), nitrate (NO3) and chloride (Cl) on a Metrohm® Ion Chromatograph; calcium (Ca), magnesium (Mg), potassium (K), and sodium (Na) on an Agilent® 730 ICP optical emission spectrometer; dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) on a Shimadzu® TOCV with a TNM-1 nitrogen (N) detector; and ammonium (NH4) by colorimetry on a SEAL Analytical AQ2 discrete analyzer at the Louis C<emphasis role="strong">.</emphasis> Wyman Forest Sciences Laboratory, Durham, NH. Dissolved organic N (DON) was calculated as the difference between TDN and inorganic N (NO3-N + NH4-N). Total mass of elements applied to the canopy as iced ‘precipitation’ was calculated as the ‘precipitation’ chemistry from the stream aliquot multiplied by the ‘precipitation’ volume for each plot.