Chemistry 



R. T. Prentki, M. C. Miller. R. J. Barsdate. V. Alexander, 

 J. Kelley and P. Coyne 



SEDIMENTS 



The chemistry of the pondwater is strongly influenced by interactions 

 with the sediments. The ponds are shallow, so there is a high ratio of 

 sediment surface to pond volume. Also, there is a high amount of 

 resuspension of the flocculent sediment caused by the constant wind. 



Sediment Particle Size 



The bottom sediments of the tundra ponds are composed mainly of 

 dark brown, highly organic, unconsolidated material. Some organic 

 particles can be identified as bits of leaves of sedges and grasses, roots and 

 moss fronds. Usually, the highly organic sediments are 18 to 30 cm thick 

 and are underlain by a layer of mixed organic matter and sand. Beneath 

 this are layers of sand and lenses of buried peat at a depth of 40 to 60 cm. 



The organic particles in the surface sediments are quite large, 

 especially close to the edge of the pond, and are poorly sorted. The data 

 come from a measurement in the middle of Pond A of a 0-2 cm sediment 

 sample which was wet sieved with metal sieves (Wentworth Scale), oven- 

 dried at 1 10°C, and weighed. The mean particle size was 500 ^m (Figure 4- 

 1) and there was a linear relationship between the cumulative percent dry 

 weight and the log 2 of particle size. This linear relationship and the low 

 slope suggest that these sediments are poorly sorted by physical processes. 

 This relationship contrasts markedly with the sigmoidal curve, steeper in 

 slope, that characterizes highly sorted beach sand. 



The ponds can be visually separated into those with mostly large 

 organic particles in the surface sediments and those with mostly small 

 particles. The intensively studied ponds, A, B, and C, fall into the first 

 category and Ponds X and D fall into the second. Pond J was so disturbed 

 by wading and destructive sampling in 1971 that it cannot be classified. 



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