Chemistry 119 



actual PP concentrations by 1 or 2 Mg liter' since the membrane filters 

 used for this (and only this) analysis retain some dissolved organic 

 phosphorus (Prentki 1976). The measurement specifically excludes 

 zooplankton large enough to be picked off filters. 



In comparison with the intensively studied ponds discussed above, 

 phosphorus concentrations are somewhat higher in other ponds we 

 studied. These differences ultimately are related to sediment chemistry 

 and will be discussed in more detail below. 



Phosphate concentrations in an 18 August 1972 transect (Figure 3-1) 

 ranged from 0.9 to 3.0 ^g DRP liter ' in 15 low-centered polygon ponds 

 and from 3.7 to 7.6 Mg P liter " ' in three trough ponds. In one low-centered 

 polygon pond with trough inputs the concentration was 4.8 Mg P liter" '. 

 The greater concentration in polygon troughs than in low-centered 

 polygon ponds parallels similar observations for many other phosphorus 

 parameters in both Barrow terrestrial and aquatic environments. Kalff 

 (1965) reports DRP concentrations of 6 and 13 Mg liter"' for two trough 

 ponds in this watershed. Our investigations indicate that the non- 

 extractive phosphate techniques used by Kalff overestimated pond 

 phosphate concentrations by approximately 45% (see Prentki 1976) due to 

 hydrolysis of organic phosphorus. When adjusted by this factor, Kalffs 

 phosphate concentrations would be 3 and 7 Mg P liter"'. The latter value 

 agrees well with the 7.2 and 7.5 Mg P liter ' we have measured upon two 

 occasions in the same pond. 



The dissolved unreactive phosphorus in all IBP ponds ranged between 

 5 and 10 times their DRP concentration. The DUP concentrations in the 

 18 August 1972 transect were also highest in trough ponds or in ponds with 

 trough inputs: in the trough ponds it was 1 8.6 to 60.6 Mg P liter " ' while in 

 the polygon ponds it was 9.8 to 24. 1 Mg P liter ~ ' . 



Three analyses of PP on two trough ponds had a range of 20.3 to 3 1 .5 

 Mg P liter ', 2 to 3 times that found in low-centered polygon ponds. 



Phosphorus concentrations in arctic lakes are similar to those of low- 

 centered polygon ponds. In Ikroavik Lake near Barrow DRP 

 concentrations ranged between 0.5 and 4.4 Mg P liter ' for 39 samples 

 taken on 17 dates, while 15 analyses from four Prudhoe Bay lakes ranged 

 from 0.2 to 1.9 Mg P liter"'. These concentrations are similar to those of 

 other arctic surface waters reviewed in Hobbie (1973), but Char Lake had 

 undetectable amounts of less than 0.7 Mg liter ' (Schindler et al. 1974). In 

 arctic Alaska, lakes in the Colville River area had to 2.8 Mg DRP liter ~ ' 

 in the summer but had 4.6 to 12.1 Mg DRP liter" ' in the winter (Kinney et 

 al. 1972). However, DUP concentrations in arctic lakes are lower than 

 those of tundra ponds. Our analyses of Ikroavik water ranged as low as 0. 1 

 Mg P liter ' in melted lake ice but normally were 4 to 10 Mg P liter"'. 

 Although the major ions are concentrated more than 10-fold due to the 

 exclusion from the winter ice cover, the concentration of DRP and DUP 

 remain relatively constant, suggesting that sediment-water interactions 

 buffer their concentration in the lake. The DUP concentration for the four 



