Deannakayte Marucut, San Francisco State University

Class Year:

Mentor:

Abstract:

Sulfide is the product of sulfate reduction which occurs under anaerobic conditions, including in marine sediments that’s been weather deprived. Sulfide is highly toxic to organisms such as worms and seagrasses that may inhabit marine sediments. Sulfate reduction may be promoted by organic matter loading, which occurs, for example, below oyster aquaculture cages. Therefore, the accumulation of sulfide is a potential undesirable consequence of bottom cage oyster aquaculture. Oyster aquaculture is a major source of commerce along the East Coast and may positively affect the nutrients/ water quality that it surrounds. Sulfate is the second most abundant anion in seawater after chloride and the proximity of sulfide accumulation under oyster cages has caused a rise of concern for environmental monitoring. Denitrification and anaerobic ammonium oxidation (anammox) are biogeochemical processes that naturally remove reactive nitrogen (N) by converting nitrate or ammonium and nitrite to N2 gas, which is released from the water to the atmosphere. The purpose of this project is to test if electrochemical interventions help remove sulfide and promote denitrification. Two methods of electrochemical interventions were tested under oyster farming cages to evaluate which is the most effective in reducing the amount of sulfide that is accumulating within the sediment. This is still an ongoing process, but preliminary data shows that benthic microbial fuel cells can generate small amounts of low voltage current, suggesting it may be mitigating sulfide accumulation. Now the challenge is trying to see if these interventions can withstand longer periods of time to mitigate the sulfide accumulation.