279-13 P-Optimal: Linking Wetland Hydrogeomorphic Gradients to Spatiotemporal Phosphorus Dynamics

Session: The Current Understanding of the Role of Wetland Hydrology in the Cycling of Elements and other Substances: A Technical Session in Memory of Paul H. Glaser

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Wetlands have an inherent ability to store phosphorus (P) and mitigate nutrient loading in downstream aquatic environments. Soil phosphorus storage capacity (SPSC) provides a critical indicator of wetland soils' ability to capture and retain P, serving as a measure of their finite capacity to act as a P sink over time.  However, many wetlands can rapidly approach saturation due to historical (legacy) phosphorus in the soil and may even act as P sources under certain conditions, such as limited hydrologic connectivity or internal biogeochemical shifts.  These risks highlight the importance of understanding the temporal and spatial variability in wetland nutrient retention performance. The ecological, hydrologic, and biogeochemical drivers of SPSC operate across multiple scales, shaped by wetland landscape gradients and hydrogeomorphic context, complicating our ability to predict when and where soils may transition from sinks to sources.

Operating for the last 5 years, the 9-acre P-Optimal R&D wetland in the Maumee River basin (Ohio) is a demonstration wetland designed to develop best management guidance for enhancing P retention in watershed wetlands. In our study, high-resolution soil samples, vegetation surveys, and continuous real-time hydrologic monitoring are utilized to determine the controlling processes of SPSC, revealing significant correlations between hydrological connectivity, landscape characteristics, and ecological gradients. These results demonstrate that spatial and temporal heterogeneity strongly influence SPSC dynamics. Our findings provide a mechanistic understanding of how hydrogeomorphic gradients drive P retention and release, improving the effectiveness of nutrient mitigation efforts in the Great Lakes Region and offering a foundation for better spatial targeting and adaptive management of wetland restoration strategies in impaired watersheds.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8042

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