Impact of Iron Discharges from Wastewater Treatment Plants on Algal Growth and Species Composition

摘要

Unialgal cultures and lake assemblages of phytoplankton were studied to determine the effect of iron enrichment on algal metabolic processes and community composition. Phytoplankton assemblages from Lake Erie and Chautauqua Lake, N.Y. were generally inhibited following enrichment with unchelated iron. The degree of inhibition in lake water was small and it occurred as a result of extracellular interactions between iron and soluble ions (phosphorus and possibly some trace metals). Increases in photosynthesis following the addition of EDTA-chelated iron to lake water was shown to result primarily from the effect of EDTA alone on algal metabolism. Lake diatom populations appeared to be the most sensitive to iron. However, iron enrichment did not enhance lake populations of blue-green algae nor did it cause major shifts in the composition of the phytoplankton community. Investigations with defined nutrient media indicated that iron enrichment stimulated the growth of unialgal cultures primarily only in nutrient-rich media.