152 



R. T. Prentki et al. 



filter. Total DOC was measured as CO 2 released from an acidified filtrate 

 by a wet combustion with acid-persulfate at 105°C in nitrogen-purged 

 ampules (in 1971) or by a combustion (650-750°C) in a tube furnace (in 

 1972, 1973). The amount of CO2 was measured with an infrared gas 

 analyzer (Menzel and Vaccaro 1964). In 1971, triplicate 1-ml ampules 

 were prepared weekly for each of several ponds. For each sample in 1972 

 and 1973, a minimum of four replicate injections of either 25, 50 or 100 lA 

 from a Hamilton syringe were averaged. 



The seasonal cycle of DOC (Figure 4-30a) begins with low 

 concentrations during the melt period in June and ends with high 

 concentrations at freezeup in September. Snowmelt water contains little 



0) 



c 

 o 

 .0 



o 

 o 



o 



'c 

 o 



■o 



> 



o 

 in 

 in 



E 



16 

 14 



12 

 10 



0.7 



FIGURE 4-30. Dissolved organic carbon and UV ab- 

 sorbance at 250 nm (1 cm) in the water of Ponds A and 

 B, 1971-1973. 



