Season 



(PCS)l/ Ca 



Mg 



Na 



HCO3 SO4 



CI 



DS 2 / H3/ 



Marsh sites 



85 

 72 



41 



43 



20 

 10 



130 

 48 



7.0 

 2.3 



218 

 166 



4.5 

 12 



200 

 67 



520 

 270 



180 

 120 



Southern canal 

 sites 



D 



U 



49 

 56 



74 

 57 



12 

 5. 



52 

 27 



3.0 



1.7 



270 

 190 



1.8 

 3.1 



80 

 44 



370 

 240 



230 

 155 



Dry season samplings - April 1973 and 1974. 

 Wet season samplings - October 1972 and 1973. 

 1/ Platinum - cobalt standard. 

 2/ Dissolved solids. 

 3/ Hardness. 



Table 13. Average concentrations of major inorganic ions and color for 



wet and dry seasons in Conservation Area 3 (in milligrams per 

 liter except where noted) (adapted from Waller and Earle 1975) 



major inorganic ions, nutrient con- 

 centrations tend to decrease toward 

 the south as agricultural runoff is 

 assimilated or trapped within the 

 marshes. Median total nitrogen 



values range between 0.6 and 1.8 

 mg/l toward the south end of Conser- 

 vation Area 3. Total phosphorous is 

 fairly low throughout Conservation 

 Area 3 and in Tamiami Canal ranging 

 between 0.00 and 0.02 mg/l (Waller 

 and Earle 1975). Nitrogen at the 

 marsh sites in the lower end of WCA 

 3 tends to increase toward the end 

 of the dry season as water levels 

 drop and ponding concentrates re- 

 maining nutrients. In Tamiami Canal 

 little seasonality is evident in 

 total nitrogen concentrations. 



Phosphorous concentrations show 

 little seasonal variation in both 

 the canal and at the marsh sites. 



Trace metal concentrations at 

 marsh stations and in Tamiami Canal 

 are presented in Table 14. Of all 

 the trace metals only iron occa- 

 sionally exceeds water quality stan- 



dards, but this is typical of the 

 soils in this area. No particular 

 seasonal or spatial trends are obvi- 

 ous in trace metal occurrence and 

 distribution. 



Organic pesticides and their 

 breakdown products seldom remain in 

 detectable concentrations within the 

 surface waters of the conservation 

 areas, although they are detected in 

 71% of rainfall samples at concen- 

 trations of 0.01 mg/l to 0.9 mg/l 

 (Waller and Earle 1975). Concentra- 

 tions were lowest at the northern 

 boundary of ENP, probably because of 

 its distance from agricultural lands 

 to the north. 



Due to their physical, chemi- 

 cal, and biological properties, many 

 pesticides (as well as trace metals 

 and nutrients) tend to accumulate in 

 organic sediments. Consequently, 

 sediments generally exhibit higher 

 concentrations of these materials 

 than the waters above them. The 

 building of organic peat soils by 



76 



