SS4.09 Does Intentional Nutrient Fertilization (N,P And Fe) Foster C Sequestration and/or Increased Fish Fertilization?
Date: Tuesday, June 11, 2002
Time: 11:45:00 AM
Location: Colwood
 
RoseAL, University of New South Wales, Sydney, Australia, a.rose@student.unsw.edu.au
Waite, T, D, University of New South Wales, Sydney, Australia, d.waite@unsw.edu.au
 
IRON REDOX CYCLING IN ESTUARINE ENVIRONMENTS
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Despite the potentially high terrestrial inputs of iron into estuaries, high biological productivity and the relative insolubility of iron mean that demand is likely to outweigh supply. We have investigated the primary abiotic factors regulating iron speciation (and hence its solubility and bioavailability) in estuarine environments - iron hydrolysis, organic complexation and sunlight-mediated photoreduction. Using a kinetic approach, the system has been numerically modelled to predict iron speciation as a function of the iron, terrestrial organic matter and sunlight input into the system and, perhaps most importantly, as a function of time. Our work suggests that iron cycling is a highly dynamic process, and that equilibrium is unlikely to be reached under natural conditions in estuaries. The system is finely balanced and sensitive to natural fluctuations such as diurnal light cycles, tidal flushing and terrestrial rainfall events as well as human activities such as land clearing and dredging.