Pore Water Ammonium 



NiTRITE+NlTRATE 



Pore water NH4* concentrations were generally much 

 higher than open water levels, with the highest values 

 recorded being in the summer and lowest values in the 

 late fall and winter (Table 6-4). At the Reference 

 Station, values ranged from 1.9 to 193 (xmoles. The 

 highest values were recorded in June 1999 (53 to 

 193 (xmoles). At Station II, values ranged between 

 4.5 and 197 |xmoles. High values (64 to 197 |jjnoles) 

 were measured over a six-month period from |une to 

 December 1999 and coincided with a fourteen-month 

 period with over 125.9 cm (50 inches) of precipitation. 

 The highest values recorded at Station III were also in 

 June through December 1999 (21 to 213 i^moles). At 

 all three stations, values appeared to gradually increase 

 over the study period (Figure 6-6), with similarly high 

 values seen during the second half of 1999. 



Open Water Nitrite+Nitrate 



At the Reference Station, NO, + NO, concentrations 

 exhibited the smallest range of values (0.4 to 

 1.8 pmoles), with the highest value being recorded in 

 February 1996 (Table 6-3). The highest overall values 

 were seen at Station III during the first sampling year 

 (1995), with values exceeding 2.3 jimoles at each 

 sampling date during that year and approaching 

 6 ^imoles in August 1995. The range of values for the 

 remainder of the study period was between 0.4 and 

 1.2 ^imoles. The values at Station II were between 

 0.3 ^imoles and 5.3 ^moles, with the highest values 

 recorded in April 1995. An additional small peak 

 occurred in December 1998 (1.9 jimoles). 



Table 6-4: Mean pore water ammonium (NH/) and nitrite+nitrate (NOj" + NO3) concentrations at each station. 



Pore water samples were taken at three lysimeters located at 0, 49 and 99 m from the water's edge. Two water 

 samples were taken at each lysimeter, and the two values averaged to determine a mean value for that distance. 

 The range of mean values at the three distances is reported. If only one number is listed, then samples were only 

 taken from one well, and dashes represent samples that could not be taken (as a result of sediments being too dry to 

 extract water). 



ChapterSix ♦ 6-13 



