Phosphorus (P) is essential for food production, but current patterns of phosphorus use are not sustainable. High-quality phosphate rock reserves, the primary source of phosphorus fertilizers, are limited, raising concerns about future availability while losses of phosphorus from farms and cities drive eutrophication in rivers, lakes, estuaries, and coastal oceans.

This session seeks to develop interdisciplinary perspectives on the phosphorus sustainability challenge and welcomes submissions across all pertinent areas of the food-energy-water nexus:

· Phosphorus biogeochemistry in marine and fresh waters · Impacts of P on water quality in freshwater and marine ecosystems · Nutrient management and ecological restoration · Connections between eutrophication and greenhouse gas emissions · Watershed studies and modelling of P sources and sinks · Advancements in P sensors and analysis · Impacts of agricultural practices on P losses to surface waters · P recycling from human wastewater and animal manure · Food system studies including economic perspectives · Impacts of diet and food waste on P cycling · Phosphorus and public policy

Lead Organizer: James Elser, University of Montana (jim.elser@flbs.umt.edu)

Co-organizers:

Eric McLamore, Clemson University (emclamo@clemson.edu)

Presentations

---

06:00 PM

Electrochemical sensor for rapid detection of orthophosphate in hydroponic water (9534)

Primary Presenter: Maria Torres, Clemson University (mtorre3@g.clemson.edu)

Orthophosphate (Ortho-P), an inorganic form of phosphorus (P), plays a crucial role in cellular metabolism and is a limiting factor in plant growth in agricultural systems. Although Ortho-P is widely used as a fertilizer, excessive application can lead to environmental issues such as eutrophication and harmful algal blooms (HABs) due to runoff. This study presents a nanohybrid sensor for phosphate detection, utilizing laser-inscribed graphene electrodes (LIG) coated with chitosan (CHI) nanobrushes. The chitosan coating was applied using Frequency Modulated Electropolymerization (FMEP) at pH 5. The resulting chitosan nanoparticles, averaging 1728 nm in diameter, exhibited good stability with a positive zeta potential of +41 mV. X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS) confirmed the successful polymerization, with four characteristic peaks demonstrating the crystallinity of chitosan and the in-plane structure of LIG. EDS also revealed 1.8% phosphate absorption at the surface of LIG+CHI after exposure to a 1000 ppm phosphate solution for one minute. Scanning electron microscopy (SEM) confirmed the successful growth of CHI nanobrushes on the LIG electrode surface, with the FMEP method effectively functionalizing the surface for ortho-P detection. Surface zeta potential analysis showed a shift in the isoelectric point from 6.1 for bare LIG to 9.5 for LIG+CHI, indicating enhanced positive surface charge and improved phosphate binding. These findings suggest that the FMEP technique and microwave-assisted chitosan nanoparticle synthesis offer a promising approach for developing phosphate sensors with strong potential for nutrient monitoring and environmental protection applications.

View Additional Details

---

06:00 PM

REFINING CHLOROPHYLL-NUTRIENT RELATIONSHIPS ACROSS THE US CONSIDERING THE EFFECTS OF DEPTH, TROPHIC STATUS, LIGHT AVAILABILITY, AND TEMPERATURE. (9262)

Primary Presenter: Brian Baird, North Carolina State University (bwbaird@ncsu.edu)

Lake eutrophication is a significant challenge for water-quality management across the world. Many management strategies focus on reducing nutrient inputs, but other environmental factors can substantially influence nutrient-algal relationships. While there have been various large-scale studies assessing how different lake characteristics impact eutrophication, there remains a need to integrate these factors into a comprehensive model.  In this study, we aim to refine chlorophyll-nutrient relationships across the United States (US) by considering auxiliary variables (e.g., depth, light, non-algal turbidity, temperature) within a Bayesian hierarchical framework. We leverage over 4000 sampling events from the National Lakes Assessments (US EPA, 2007-2022) to inform model development. We first consider auxiliary variables independently, exploring how they influence the critical nutrient ratio (nitrogen:phosphorus) and the chlorophyll-to-limiting-nutrient ratio. Results indicate substantial variability in these ratios, particularly related to trophic status and depth. Next, we integrate significant variables into a comprehensive model for chlorophyll prediction. We apply the model to map nitrogen versus phosphorus limitation, as well as sensitivities to other factors (like temperature), across the US. Our model can serve as an effective tool to aid water resources management, particularly at large spatial scales.

View Additional Details

---

06:00 PM

Metaproteomic insights into trace metal-dependent phosphorus utilization within North Atlantic phytoplankton communities (9715)

Primary Presenter: Viktoria Steck, Woods Hole Oceanographic Institution (viktoria.steck@WHOI.edu)

Oceanic phytoplankton sustain life on earth by contributing roughly half of the global net primary production. In the North Atlantic Sargasso Sea, low concentrations of the essential nutrient phosphorus (P) can limit marine microbial growth, community structure, and productivity. To cope with P scarcity, microorganisms express metal-containing hydrolytic enzymes to access the alternative pool of dissolved organic P (DOP), a process dependent on trace metal availability in the marine environment. Recently, various globally important and taxonomically widespread enzymes have emerged in ocean genomes, including diverse alkaline phosphatases and other hydrolases. However, the roles of these proteins in supporting ocean ecosystem fertility, and the relationship between P and trace metal cycling are not fully understood. To shed light on this, ambient measurements and metal-addition shipboard incubations were conducted on the 2024 BIOS-SCOPE cruise around BATS that combine in situ DOP hydrolysis rates with community metaproteomics, P pools, and trace metal concentrations. Ambient results show that DOP utilization varied greatly with mixed layer depth and microbial community composition. Incubation results demonstrated that iron (Fe), zinc (Zn), and cobalt (Co) availabilities constrained hydrolysis rates and substrate preferences. Metaproteomics provide new knowledge on the enzyme sequences involved in phytoplankton responses to nutrient stress, which is especially relevant in light of future increasing P limitation across the world’s large ocean gyres.

View Additional Details