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
04:30 PM
Taking the pulse of phosphorus sustainability: challenges and solutions across the land, freshwater and marine continuum (9760)
Tutorial/Invited: Tutorial
Primary Presenter: Philip Haygarth, Lancaster University (p.haygarth@lancaster.ac.uk)
This paper will present a state-of-the-art view on the current position on phosphorus sustainability as an introductory perspective for the session. It is only a few decades since the world started commercial distribution of rock phosphate and in the short time it has had a significant positive influence on our lives. Phosphorus undoubtedly enhances our ability to produce crops and food, and this has been a significant player in feeding many parts of the world, but there remain challenges in distribution and access to appropriate levels of phosphate fertilizer in some soils and regions of the world. Much of the phosphorus that is applied to soil is stored away in immobile (‘organic’ and other) forms, with only a small proportion seeming to be available for uptake for plant benefits. The challenges ahead lie in balancing and regulating the inputs of new phosphorus with recycled phosphorus forms, such as animal manures, and seeking plants that can access the normally ‘immobile’ forms. As well optimizing the sustainable use of new phosphorus in agricultural systems, another great priority lies in controlling the transfers of phosphorus from agriculture to water, where it can have a damaging influence on rivers lakes and oceans. This is a complex ‘wicked’ problem, where the transfer from land to water moves at varying speeds, often taking decades to move through river catchments, giving rise to the popular term ‘legacy’ phosphorus. Whilst phosphorus for food production must continue to be celebrated and implemented in an appropriate way, the sustainability challenge lies in managing and regulating the inputs of new phosphorus, making use of recycled phosphorus where we can, and in preventing the long-term transfer to the oceans. There have been seven global sustainable phosphorus summits across most continents of the world, and next year the eighth summit #SPS8Africa is scheduled to be in Ghana, West Africa 30th September - 3rd October 2025. We invite you to join us to help tackle some of these complex issues.
05:00 PM
NEW PHOSPHORUS BUDGET FOR LAKE ERIE IMPLIES MAJOR INPUT FROM COASTAL EROSION (9566)
Primary Presenter: Serghei Bocaniov, University of Waterloo (sbocaniov@uwaterloo.ca)
In large lakes, phosphorus (P) input from coastal erosion, including the fraction that can be incorporated in the aquatic food web (AFW), is often overlooked compared to P inputs brought by river discharge and atmospheric deposition. Here, we compare two independent approaches to estimate the P input to Lake Erie (Canada, USA) associated with coastal erosion processes. The first approach relies on direct coastline retreat measurements while the second approach is based on whole-lake P mass balance modeling. The latter builds on a recently revised lake budget of total P (TP) averaged over the period 2003-2016. We expand this budget by explicitly accounting for TP that is incorporated in phytoplankton, zooplankton, fish, and zoobenthos. The difference between known external inputs and output via lake outflow and sediment burial reveals that (1) an additional amount of 3,400 metric tonnes per year (MTA) of TP must enter the lake, and (2) P uptake in the AFW is significantly unbalanced, hence, further highlighting the existence of an additional source of bioavailable P. We propose that the additional P input is caused by coastal erosion. Mapping of coastline retreat rates combined with preliminary P concentration data for soil samples from eroding bluffs in Lake Erie shows that the magnitude of the P input related to coastal erosion is of the same order of magnitude as that derived from the TP budget calculations. An emerging concern for Lake Erie, and similar large freshwater lakes, is the possible acceleration of P enrichment by coastal erosion driven by climate change.
05:15 PM
Field observations show that microcystin concentration increases when phosphorus (without nitrogen) is reduced (9161)
Primary Presenter: Charlotte Schampera, TU Berlin (schampera@tu-berlin.de)
Cyanobacterial harmful algae blooms (e.g. those of Microcystis) and their toxins (e.g. microcystins - MCs) threaten the safe use of lakes for drinking and recreation and this hazard is expected to increase in a warming climate. This is an urgent environmental problem, but there is no scientific consensus about the best management approach. Reducing inputs of the growth-limiting nutrient phosphorous (P) can be successful in decreasing cyanobacterial biomass but the effect on toxin concentration is unclear. The underlying mechanisms, and evidence from laboratory experiments and models suggests toxin concentrations may actually increase. What has been missing is field data to support or refute this hypothesis. Here, we present two analyses of the National Lakes Assessment (NLA) dataset. The first focuses on changes in MC concentration within individual lakes across time. In the second analysis, we applied Generalized Additive Models (GAMs) across all lakes and time points. Both analyses show that when P only is reduced, Chlorophyll a decreases but MC concentration does not decrease proportionally. In fact, MC concentration increases for moderate P reductions and only decreases for more extreme P reductions. A dual reduction of nitrogen and P, however, results in a decrease of biomass and toxins. This supports a management approach of dual nutrient reduction.
05:30 PM
A dip-and-read impedimetric electrochemical sensor for orthophosphate monitoring (9531)
Primary Presenter: Eric McLamore, Clemson University (emclamo@clemson.edu)
Phosphorus (P) is an essential element for all life forms and a finite resource. The P cycle in ecosystems plays a vital role in most biological pathways, making it a limiting nutrient. For agriculture, inorganic P is a primary component of fertilizers and is obtained primarily through extractive mining. Excessive application of P fertilizers causes detrimental ecosystem effects such as eutrophication. As a result, there is a pressing need for conservation and management of nutrient loads through analytical techniques to precisely measure orthophosphate in aquatic systems. Here, we test a new two-dimensional sorbent nanomaterial containing graphene oxide and a polyelectrolyte which is known to bind anions (diallyldiethylammonium chloride). The hybrid material is applied for sensing orthophosphate in aqueous samples at what pH range? Geisis worked on pH 8. Laser-induced graphene electrodes were coated with the sorbent nanomaterial. Material analysis was based on zeta potential in different solutions, electron microscopy and X-ray spectroscopic analysis of the electrode coating. Preliminary electrochemical characterization of the functionalized LIG electrode used open circuit potential, cyclic voltammetry, and impedance spectroscopy. After initial characterization, impedance spectroscopy was used as the transduction technique for capacitive sensing of orthophosphate in water samples with a detection limit of 60 ± 5 ppb. Equimolar selectivity assays show the chemsensor was 97% more selective for ortho-P over potassium hydrogen phthalate, bicarbonate, and Tris (a zwitterionic buffer); at least 93% more selective over chloride and nitrate, and at least 87% more selective than sulfate. The developed sensor can be reused after surface regeneration with a regeneration solution (pH 5), and is a low cost sensor platform for scalable development of chemosensors. We have developed first generation mobile phone applications to be used with the sensor for rapid decision support.
05:45 PM
TAKING STEPS TOWARDS PHOSPHORUS SUSTAINABILITY: HIGHLIGHTS FROM THE NSF SCIENCE AND TECHNOLOGIES FOR PHOSPHORUS SUSTAINABILITY (STEPS) CENTER (8947)
Primary Presenter: James Elser, James Elser (jim.elser@flbs.umt.edu)
Most aquatic scientists engage the phosphorus (P) sustainability challenge from downstream, i.e., the widespread eutrophying effects of phosphorus pollution on rivers, lakes, and oceans. Mitigating these impacts has proven to be a vexing problem as widespread use of P is essential for supporting the food system in the form of fertilizers and feed additives. Furthermore, supplies of phosphate rock to produce fertilizer are found in only a few countries and concerns have been raised about long-term access to affordable P for fertilizer production. Addressing the P sustainability challenge requires system-level thinking at the intersection of multiple disciplines ranging from limnology to soil science and from engineering to sociology. To help meet this challenge, in 2021 the US National Science Foundation (NSF) funded a large ($25M) Science & Technology Center (STC), the Science and Technology for Phosphorus Sustainability (STEPS) Center. This talk will describe the structure and operating philosophy of this convergence research center, highlight some of its most recent work, and discuss its future trajectory in the context of the broader global phosphorus sustainability movement.
SS39 - Taking the pulse of phosphorus sustainability: challenges and solutions across the freshwater to marine continuum
Description
Time: 4:30 PM
Date: 31/3/2025
Room: W205CD