Chemistry 77 



100 



1000 



500 250 125 



Particle diameter, /xm 



63 



FIGURE 4-1. Cumulative percent of dry 

 weight of surface sediments of different sizes 

 in Pond A, June 1973. 



Bulk Density 



A measurement of the bulk density takes into consideration both the 

 water content of the sediments and the density of the soil material; in 

 Ponds B, C, D, and E the mean was 160 mg dry wt cc"' (Table 4-1). 

 However, these ponds were certainly on the low end of the spectrum, as 20 

 ponds in the old lake basin had a range of bulk density from 65 to 1096 mg 

 dry wt cc ~ '. The high values come from trough ponds where the sediments 

 contain much inorganic matter; the modal class of these 20 measurements 

 was 100 to 150 mg dry wt cc '. 



TABLE 4-1 Bulk Density, Percent Organic Matter, and Organic Carbon in 

 the Top 1 cm of a Square Meter of Pond Sediments 



Pond 



D 



Bulk density 

 (mg dry wt cc'' ) 



150 



Organic content of 



surface sediments (% dry 



wt) 82.8 



157 205 126 



83.4 69.0 79.1 67.6 



74.4 



Organic carbon 



(g m "2 ) 



496 



523 566 400 



