Chemistry 139 



1500 



"T r 



(A) 0-1 cm 

 (•) 1-30 cm 

 (o) Permafrost 



20 



40 

 Iron, mg g" 



60 



FIGURE 4-21. Total phosphorus per gram of 

 sediment of Barrow ponds vs. total iron per 

 gram of sediment. The solid line denotes the 

 least squares fit of all the data points while the 

 dashed line denotes the least squares fit of data 

 from sediments deeper than 10 cm. 



sorption, rather than by precipitation as a discrete mineral. This 

 conclusion is supported by a correlation matrix of phosphorus 

 fractionations (Chang and Jackson) and iron concentrations for the 

 to 1 cm Pond C sediment sample given in Table 4-18, and for three other 

 to 1 cm Pond C sediment samples described in Prentki (1976). The 

 resulting correlation matrix for the four sediments (Table 4-21) shows a 

 significant correlation with total iron for sediment inorganic phosphorus 

 (r = 0.97*) and the sum of NH4F-P-l-first NaOH-P (r = 0.96*), the two 

 pools that contain most of the total inorganic phosphorus as well as the 

 kinetically active portion of the inorganic phosphorus. These positive 

 within-pond correlations with total iron support the hypothesis that 

 sediment phosphate is bound by iron. 



