58 M.C. Miller etal. 



18 



16 



14 



12 



^ 10 



41- 



"T 1 1 1 1 — 1 1 — I — I 1 — I 1 1 1 1 1 r 



Bottom of Water Column 



10 20 

 Jun 



10 20 

 Jul 



10 20 

 Aug 



FIGURE 3-5. Daily average sediment temperatures 

 at the bottom of the water column and at 10-cm 

 depth in the sediment in Pond B, 1972. 



the morning and cool more slowly than the water in the evening, these 

 sharp rises have little effect on the overall average. 



The daily temperature oscillations are also evident at the 10 cm 

 sediment depth but these deep sediments are colder than the surface 

 sediments and the daily temperature range is less than one-quarter of that 

 at the surface (Figure 3-5). At 10 cm the average temperature is 2.3°C 

 below the mean at the sediment surface (Table 3-3) and the oscillations are 

 greatly damped. In addition, the higher temperatures move downward 

 through the sediments in a wave so that there is a 7-hour delay between the 

 time of the temperature maximum at the surface of the sediments and the 

 maximum at 10 cm. As might be expected, the daily temperature range at 

 10 cm is only 1.5°C. Thus the wave has both a time lag and a decrease in 

 amplitude as it moves downward. 



The only comparable data are those of Brewer (1958) for Imikpuk 

 Lake (around 2 m deep) and two other Barrow area lakes. The surface 

 sediments were always the same temperature as the water column in these 

 lakes and the rate of temperature decrease, approximately 2°C per 10 cm, 

 agreed with the pond data. One difference was that the lake sediments 

 reached their maximum temperature in mid-August, one month after the 

 maximum in the ponds, but this is merely a reflection of the parallel 

 situation for the water temperatures in lakes and ponds. 



