Organically bound iron in lake sediments and its availability to uroglena americana, a freshwater red tide chrysophyceae.

Abstract

Organically bound iron in the interstitial water of a lagoon sediment was fractionated successively by ultrafiltration, cation exchange column, and gel-filtration. Each fraction was bioassayed for iron availability to a fresh water red tide Chrysophyceae, Uroglena americana. Iron bound to anionically charged ninhydrin reactive organic compounds (molecular weight around 300-600 dalton) promoted the growth of U. americana. Iron-complexing capacity of interstitial water was estimated at ca. 14 μM as an equivalent concentration of iron available to U. americana.