The distribution of iron in a closed ecosystem

Summary

There was not a significant correlation of iron to trace metals or to phosphorus in the sedimenting material. There was a large amount of iron returning from the sediments into the open water that must not have been available for biological uptake. Even though the community appeared to secrete a low molecular weight substance to chelate the iron, most of the iron not in the seston was associated with magnesium in a molecular size range of 1,000 to 10,000. The periphyton community where nitrogen fixation occurred contained four times the iron concentration as that where nitrogen fixation was low. The phytoplankton samples that were fixing nitrogen had the highest rates of ⁵⁸Fe uptake.