RAPID: Phosphorus Molecular Biogeochemistry during a Rapidly Changing Nutrient Load in Tampa Bay, FL

In late March 2021, a reservoir containing 500 million gallons of wastewater from a fertilizer production plant began leaking into nearby Tampa Bay, Florida, and then was drained into the bay when the reservoir looked to be in danger of catastrophic failure. This drainage added over a year’s worth of phosphorus (P) and nitrogen to the bay in a two-week period.

The effects of this rapid addition of these critical nutrients on the local ecosystem will be investigated by specifically focusing on changes to the molecular chemistry of phosphorus. This in turn will help understand how life adapts to rapid changes to the local environmental nutrient load. Given that such rapid infusions of nutrients are a growing problem in many water bodies throughout the world, understanding the biological response to such events could in turn help mitigate future problematic phosphate infusions.

Much of the research for this project will be conducted by graduate students at the University of South Florida as part of their scientific training.

The biogeochemical response of algae and microorganisms within the bay to this rapid change in nutrient load will be investigated. This will be accomplished by analyzing water and particulates along a cross section of Tampa Bay, from the north side that has yet to be infiltrated by a high P nutrient load, to the south where the discharge occurred. Samples will be taken both at the surface and at depth, and will be taken over the course of one year, which is estimated as a possible residence time of this high nutrient load.

Samples will be analyzed primarily by 31P NMR (nuclear magnetic resonance spectroscopy), which provides an in-depth analysis of the bulk molecular P chemistry, distinguishing between various P molecules such as inorganic P compounds (e.g., orthophosphate), polyphosphates (e.g., pyrophosphate), organophosphate monoesters (e.g., lipid phosphates), organophosphate diesters (e.g., DNA), and phosphonates (e.g., methylphosphonate). Total phosphorus will be determined by ICP-OES (inductively coupled plasma-optical emission spectrometry).

Spatial and temporal data on the molecular products of a rapidly changing nutrient load will provide a better understanding of how organisms adapt to this changing system. For instance, rapid growth may simply result in more biomolecules such as orthophosphate monoesters and diesters being produced, and as such, the P released by this discharge is unlikely to persist in the environment as P flushes out.

However, if the phosphorus is instead stored within refractory polyphosphates and phosphonates, then this may implicate a longer P residence time, as these molecules indicate a longer-term storage of P by microorganisms. The overarching goal will be to better constrain how microbes incorporate excess phosphorus into their biochemical molecules for long-term storage.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.