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

在美国和世界范围内，快速的城市化和农业集约化导致了包括湖泊、河流和河口在内的地表水系统中广泛的营养物质富集，这一过程通常被称为富营养化。在磷限制的地表水系统中，富营养化已被证明会导致水质下降、氧气消耗、水生生物群丧失和有害藻华的发生。频繁的有害藻华对依赖地表水提供饮用水、捕鱼、娱乐活动和旅游的社区产生不利影响。本ERI项目的总体目标是调查顽固性有机磷物种对地表水系统中有害藻华发生的作用和影响。为了推进这一目标，本ERI项目的负责人建议重点研究肌醇磷酸（IP）作为一种重要的、具有代表性的顽固性有机磷形式，以及它对赤潮藻华发生的影响。该研究的两个关键目标是：1)量化地表水系统中可溶性活性磷（正磷酸盐）的形成；2)评估由IP去磷酸化产生的活性正磷酸盐如何引发和维持赤潮。这个项目的成功完成将通过发展新的基础知识来指导控制和减轻有害藻华，从而造福社会。进一步的社会效益将通过学生教育和培训来实现，包括指导佐治亚南方大学的两名研究生。无机磷对地表水系统中有害藻华（HABs）的发生、频率和强度的作用已经得到了很好的了解。有机磷对有害藻华的作用和影响也已确定。然而，对有机磷（Po）的生物利用度及其在促进和维持有害藻华中的作用的基本认识和量化仍然是难以捉摸的。该ERI项目将解决这些关键的知识差距。更具体地说，首席研究员（PI）建议将重点放在评估和量化肌醇磷酸（IP）的贡献上，肌醇磷酸（IP）是一种重要且具有代表性的顽固性Po，对正磷酸盐（OP）和其他可溶活性磷（SRP）物种的贡献，这些物种为赤潮提供燃料和维持。本研究的具体目标是：1)量化地表水系统中IP微生物矿化产生的Po量；2)通过测量藻类获取磷的速率，评估IP生物降解性与其在启动和维持藻华中的作用之间的关系，从而评估IP的营养潜力；3)揭示IP优先矿化的环境介质的物理化学性质（即OP和总磷（TP）比率、pH、氧化还原电位和IP迁移率）。该项目的成功完成可能会产生变革性的影响，通过产生新的知识和数据，促进对IP对地表水系统中有害藻华的发生和持续的作用和影响的基本理解。为了实现ERI项目的教育和推广目标，PI将为参与营养管理的利益相关者制定一个推广计划，讨论有机磷在富营养化中的作用，目的是改善磷控制策略，防止有害藻华。此外，PI计划将研究成果整合到他目前在佐治亚南方大学教授的环境工程本科/研究生课程中。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.