Shannon Entropy of Released Phosphorus From Field-Burned Ash in a Simulation System with Soil and Water Columns.

This research was conducted with a simulation system with soil (sediment) and field water collected from the Everglades in columns (PVC tubes) of 60 cm in length and 10 cm in diameter. The column was consisted of 25 cm sediment and 25 cm of waters either from moderately impacted zone (M2) or highly impacted zone (H2). Three application rates of field burned ash of cattail (H2) or cattail and sawgrass (M2) were employed: 0, 1 and 5 mg per cm². The waters were sampled 17 times. Ten ml water was collected from each column every time: 5 ml was filtered for ortho-phosphorus analysis and the other 5 ml was not filtered but digested for total phosphorus analysis. The simulation was taken 8 weeks. Based on the total phosphorus level at each time, Shannon entropy and homogeneity index were calculated. The 5 mg per cm² application rate basically had greater Shannon entropy and greater homogeneity index. This indicates that larger amount of burned ash left in the field keeps greater and more constant release of phosphorus to the water body in the Everglades. This may not favor the restoration of the water quality in the Everglades.

Key words: total phosphorus; simulation; Shannon entropy; homogeneity index.