Dissertations and Theses @ UNI


Open Access Thesis


Water--Purification--Phosphate removal.; Denitrification.; Wetlands--Environmental aspects.; Academic theses;


Surface water quality is currently one of the most important environmental issues facing the state of Iowa since the ecological and recreational health of water bodies are threatened by non-point pollution. Most of Iowa's lakes are polluted because of their high concentration of nutrients, often phosphorus (P), which leads to excessive algal growth (eutrophication). To prevent eutrophication, it is necessary to prevent P from entering surface waters or to sequester (make unavailable to algae) the P that is already in the water body. One method to achieve this is to introduce substances that can tightly fix P (sorption).

Previous studies have shown that oxidized iron contained in mine tailings can sequester P from P-enriched aerobic and anaerobic surface water. Under anaerobic conditions, the re-oxidation of reduced iron is facilitated by oxidizing with a more positive redox potential than the ferric/ferrous couple (such as the nitrate/nitrogen couple). In this study, we investigated whether very high concentrations of oxidized iron would inhibit denitrification in wetland sediments. We found that denitrification is inhibited when tailings are added to artificial mixtures amended with a pure culture of the iron reducing bacterium Desulfotomaculum sp., but is not inhibited when natural wetland sediments are added. These results indicate that microbial consortia present in anaerobic wetland sediments will continue to remove nitrate after high levels of oxidized iron are added to sequester P.

Year of Submission


Degree Name

Master of Science


Department of Biology

First Advisor

Edward J. Brown


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Date Original


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1 PDF file (93 pages)



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