Phosphate-Mineral Interactions and Potential Consequences for Nutrient Cycling

Richard Hunter Oates, S.M., 2008
William Martin, Advisor

Biogeochemical cycling of phosphate is a key component in the overall production rate of coastal ecosystems. Mineral phases in the near-shore sediments play a significant role in the return of phosphate remineralized in the upper sediments to the water column. Sequential Extraction (SEDEX) of the solid-phase associated PO4-3 yielded reservoir profiles of phosphate at three sites off of the Massachusetts coast. These extractions found Fe-associated PO4 to be the dominant phase associated with rapid porewater-solid P exchange. Additionally, a seasonal enrichment/depletion pattern of phosphate fluxes relative to total carbon was observed from the sediments. These observations established the behavior of phosphate in coastal sediments as interconnected with the ongoing Fecycling in the sediments as well.