Marine sediments--Florida--Florida Bay

Different physiochemical processes control phosphorus storage in subtropical versus temperate estuaries; however, few studies are available on sediment phosphorus storage from the subtropics. In this study, solid-phase phosphorus pools of northeastern Florida Bay's sediments were examined by sequential chemical extractions, separating phosphorus into exchangeable, iron-bound, calcium-bound, and residual organic fractions. Calcium-bound phosphorus was the dominant fraction, accounting for approximately 60% of the total phosphorus and 93% of the inorganic phosphorus. Residual organic phosphorus was the second dominant fraction, accounting for 37% of the total phosphorus. In contrast to calcium-bound and residual organic phosphorus, the concentration of iron-bound phosphorus was low, indicating a limited role of iron in long-term phosphorus storage. The fine-grained carbonate sediments of Florida Bay probably account for the large pool of calcium-bound phosphorus, while the proximity of the mangroves to the northeastern section of the Bay may account for the high residual organic pool of phosphorus.

An analysis of the waters, microphytobenthos, and carbonate marl sediments of Florida Bay was performed using ion-paired RP-HPLC-PDA for chemotaxonomic characterization of past and present photoautotrophic, communities. Application of regression formulae was determined to be applicable for the waters, microphytobenthos, and surficial sediments (0--5 cm) of Florida Bay using chemotaxonomic principles. Loss of chemotaxonomically important pigments with depth prevented similar application in deeper strata (>5 cm), however, past oxic and anoxic trends could be determined. Sedimentary alteration of pigments are characterized by: rapid conversion of chlorophylls-alpha and bacteriochlorophylls-alpha to their respective pheophytins-alpha, creation of a 'carotenoid diol-cluster', equilibrium isomerization of beta-carotene (15-cis and trans), and rapid conversion of pyropheophorbide-alpha to cyclopheophorbide-alpha. An abundant presence of pyropheophorbide-alpha steryl/hopanoid esters and an unusual relationship between organic carbon and water content providing the sediments with polymeric characteristics were also found.