pphotosynthetic 

 work 



degraded energy 

 {waste heot) 



-absorbed 

 insolation 



Figure 6, 

 system. 



Simplified subsystem model of Hillsborough County natural production 



some energy must be degraded in any real process. The first law states that 

 the sum of the flows into and out of any interaction must be equal, whereas 

 the second law or principle requires all interactions must have heat sinks for 

 losses of unusable degraded energy. A separate evaluation should be set up 

 for each of the subsystems being studied. It is necessary to include in this 

 table all storages and flows of energy identified on the systems diagram pre- 

 pared earlier. It is also necessary to document the calculations and relevant 

 references for each of the flows and storages. 



Figure 7 is an example of the results of evaluating the natural produc- 

 tion system shown in Figure 6. The area of each natural ecosystan in the 

 county was obtained from a 1978 map of Hillsborough County, Florida (Hills- 

 borough County Environmental Protection Commision 1979). The solar insolation 

 of a natural system was calculated by multiplying the solar insolation for 

 Hillsborough County (1.5 x 10° cal/m^/yr) by the land area of the natural 

 system (1.23 x 10° m2) yielding a total solar insolation of 1.84 x 10l4 

 cal/yr. Eighty-six percent of the solar energy (1.6 x 10l4 cal /yr) is 

 absorbed leaving an albedo (reflection) of 14% (2.6 x 10^3 cal/yr). 



Next the energy stored in the biomass of Hillsborough County's natural 

 system is calculated (see Table 2). The land area of each ecosystem is multi- 



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