Date of Award

8-1992

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Ocean Engineering and Marine Sciences

First Advisor

John H. Trefry

Second Advisor

John G. Windsor

Third Advisor

Robert H. Fronk

Fourth Advisor

N. Thomas Stephens

Abstract

Fine-grained, organic-rich sediments are a potentially importment reservoir for nutrients and contaminants in the Indian River Lagoon, Florida. However, little is known about the behavior of these chemical species and whether they can be released to the overlying water column. In that regard, this study had two objectives: (1 ) to determine the concentrations of dissolved nitrogen and phosphorus species and some metals in representative muck deposits and the fluxes of these species to the overlying waters of the Indian River Lagoon; and (2) to identify the mechanism controlling concentrations of nutrients and trace metals in these muck deposits. Results show that intense early diagenesis of organic matter occurs in these muck sediments. Nitrate was completely reduced to ammonia in all samples and sulfate was reduced to sulfide with increasing depth in the sediment. Diffusive fluxes from muck sediments to overlying water range from 1 to 3 mole/m2/yr for ammonia, 0 .1 to 0 .2 mole/m2/yr for phosphate, 0 .1 to 0 .2 mole/m2/yr for iron, and 0 .0 1 to 0 .1 mole/m2/yr for manganese, respectively. The benthic fluxes of ammonia and phosphate are significant compared with the riverine inputs. In Turkey Creek, benthic ammonia flux accounted for 44% of total input of ammonia and the benthic phosphate flux accounted for 25% of total phosphate input. Formation of precipitates of metal sulfides, phosphates and carbonates control trace metal behavior. Overall, the study shews that muck deposits have a significant impact on riverine and estuarine environments and balances of nutrients and selected metals.

Comments

Copyright held by author

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