rainfall compared to the other sampling years. The 

 range of values at the Reference Station following the 

 same event decreased only at m by 6 ppt, but 

 increased at 49 m by 2 ppt and 45 ppt at 99 m. 



Ammonium 



Open Water Ammonium 



Concentrations of NH4* at the Reference Station 

 exhibited the greatest variation (0.9 to 14.7 jimoles ), 

 with peak values occurring in September 1996 

 (12.1 (imoles ) and June 1999 (14.7 ^moles ) 

 (Table 6-3). The increase in September 1996 

 coincided with a peak at Station II. The June 1999 

 peak occurred during a period of 4 months with over 

 30.2 cm (12 inches) of rain. 



At Station II, concentrations resembled those at 

 Station III, except for a peak value of 9.4 |imoles in 

 September 1996, 51.6 (omoles in January 1997 and two 



peaks of 6.4 ^imoles in December 1998 and January 

 1999. ITie first peak occurred during a period with 

 more than 22.7 cm (9 inches) of rain in two months, 

 and the last two peaks followed the October 1998 

 event, which flooded the station. Values prior to the 

 event were in the average range for that time of year 

 (2.7 (imoles), but were more than t«.ice as high 

 following the event. The concentration decreased by 

 60% in the following five months to near 4.0 ^unoles, 

 which represented the fall peak range under non-event 

 conditions. 



At Station III, concentrations cycled over the study 

 period, with low values (~2.0 to 3.0 |jmoles) being 

 obser\xd in the late fall and winter. Values increased 

 from winter to spring and peaked in the late summer 

 or fall (4.0 to 6.0 (jmoles). Station III exhibited the 

 smallest range of values, 1.6 to 9.5 [ijnoles. 



Table 6-3: Mean open water ammonium (NH/) and nitrite+nitrate (NO2 -•- NO3') concentrations at each station. 



Values are reported ± SE. (n = 4). Samples acquired prior to September 1996 represent only one water sample and 

 therefore do not contain SE. Dashes indicate times when samples could not be taken. 



6-12 



Vegetation Communities 



