Phosphate-mineral interactions and potential consequences for nutrient cycling

Abstract

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 P04-3 yielded reservoir profiles of phosphate at three sites off of the Massachusetts coast. These extractions found Fe-associated P04 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 Fe-cycling in the sediments as well.