ERI: Quantifying Inositol Phosphate Dephosphorylation to Understand the Role of Recalcitrant Organic Phosphorus Forms on Harmful Algal Blooms in Freshwater Systems

Rapid urbanization and agricultural intensification in the United States and worldwide have led to a widespread nutrient enrichment, a process commonly referred to as eutrophication, in surface water systems including lakes, rivers, and estuaries. In phosphorus-limited surface water systems, eutrophication has been shown to cause a decrease in water quality, oxygen depletion, a loss of aquatic biota, and the occurrence of harmful algal blooms (HABs). Frequent HABs have an adverse impact in communities that rely on surface water bodies for drinking water, fishing, recreational activities, and tourism. The overarching goal of this ERI project is to investigate the role and impact of recalcitrant organic phosphorus species on the occurrence of HABs in surface water systems. To advance this goal, the Principal Investigator of this ERI project proposes to focus on inositol phosphate (IP) as an important and representative form of recalcitrant organic phosphorus, and its impact on the occurrence of HABS. Two key objectives of the proposed research are to 1) quantify the formation of soluble reactive phosphorus (orthophosphate) from IP in surface water systems and 2) assess how reactive orthophosphate species generated from the dephosphorylation of IP initiate and sustain HABs. The successful completion of this project will benefit society through the development of new fundamental knowledge that could guide the control and mitigation of HABs. Further benefits to society will be achieved through student education and training including the mentoring of two graduate students at Georgia Southern University.

The role of inorganic phosphorus on the occurrence, frequency, and intensity of harmful algal blooms (HABs) in surface water systems is well understood. The role and impact of organic phosphorus on HABs have also been established. However, a fundamental understanding and quantification of the bioavailability of organic phosphorus (Po) and its role in promoting and sustaining HABs remains elusive. This ERI project will address these critical knowledge gaps. More specifically, the Principal Investigator (PI) proposes to focus on the evaluation and quantification of the contribution of inositol phosphate (IP), an important and representative recalcitrant Po, to the total pool of orthophosphate (OP) and other soluble reactive phosphorus (SRP) species that fuels and sustain HABs. The specific objectives of the research are to: 1) Quantify the amount of Po produced from the microbial mineralization of IP in surface water systems; 2) Assess the nutritive potential of IP through evaluations of the relationships between IP biodegradability and its role in initiating and sustaining HABs via measurements of the rates of phosphorus acquisition by algae; and 3) Uncover the physical-chemical properties of the environmental media (i.e., OP and total phosphorus (TP) ratios, pH, redox potential, and IP mobility) in which IP is preferentially mineralized. The successful completion of this project has potential for transformative impact through the generation of new knowledge and data to advance the fundamental understanding of the role and impact of IP on the occurrence and persistence of HABs in surface water systems. To implement the education and outreach goals of this ERI project, the PI will develop an outreach program for stakeholders involved in nutrient management to discuss the role of organic phosphorous on eutrophication with the goal of improving P control strategies to prevent HABs. In addition, the PI plans to integrate the research findings into the Environmental Engineering undergraduate/graduate courses that he is currently teaching at Georgia Southern University.

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.