Hypolimnetic Oxygenation Mitigates the Effects of Nutrient Loading on Water Quality in a Eutrophic Reservoir

Climate change is predicted to have many diverse effects on freshwater lakes and reservoirs by increasing both hypolimnetic hypoxia and runoff, which will increase nutrient concentrations and degrade water quality. Hypoxic conditions can trigger the release of metals and nutrients from the sediments, i.e., internal loading, while storms can increase external nutrient loading to a waterbody. One potential solution for combating hypoxia is to use side stream supersaturation (SSS), a novel form of hypolimnetic oxygenation. First, in Chapter 1, I tested the efficacy of SSS operation to improve water quality in Falling Creek Reservoir (FCR), a shallow, eutrophic, drinking water reservoir. I found that SSS operation successfully increased hypolimnetic oxygen concentrations in FCR and suppressed internal loading of iron, manganese, and phosphorus. In Chapter 2, I manipulated inflow volumes to FCR and used SSS as a tool to alter hypolimnetic oxygen conditions in whole-ecosystem manipulations of internal and external nutrient loading. I observed that internal nitrogen and phosphorus loading during hypoxic conditions largely controlled the hypolimnetic mass of nutrients in FCR, regardless of inflow volumes, presumably as a result of the accumulated nutrients in its sediment from historical agriculture. Additionally, FCR consistently functioned as net sink of N and P throughout almost all of the treatments and substantially reduced nutrient export to downstream ecosystems. In summary, my research demonstrates the sensitivity of reservoir water quality to global change.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Biological Sciences

Department dc:contributor.department

Biological Sciences

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2015

Author dc:creator

• Gerling, Alexandra Beth

Chair dc:contributor.committeechair

• Carey, Cayelan C.

Committee members dc:contributor.committeemember

• Barrett, John E.
• Little, John C.

• hypoxia
• oxygenation
• internal loading
• external loading
• Water quality

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

vt_gsexam:6155

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/75152