20 Advances and Applications in Water Resources of the Intermountain West

Monday, 19 May 2025
3:45 PM - 5:30 PM
Cascade D

USING POREWATER CHEMISTRY AND STABLE ISOTOPES TO INVESTIGATE PHOSPHORUS ADDITION TO UTAH LAKE, UTAH

Paper number: 20-2
Program: Theme Sessions
Time: 4:00 PM – 4:15 PM

Authors

Abstract

Quantifying natural inputs of phosphorus (P) into lacustrine systems is essential for nutrient management decisions. The addition of P through lake sediment porewater has not been well studied, but recent work has shown significant potential.

We present the P diffusive and advective porewater gradients from two sediment freeze cores from Utah Lake, Utah collected in fall 2024. One core was taken mid-lake to represent a deep-water location (UTL24-DW) and the other core was taken between the Lindon Marina and Timpanogos Special Service District representing a near shore location adjacent to a wastewater treatment plant (UTL24-TSSD).

Using stable hydrogen (δ2H) and oxygen (δ18O) isotopes along with geochemical analysis of the porewater, we compare near shore versus deep water P fluxes. Analysis showed minimal distinction in the UTL24-DW δ2H / δ18O isotope values with depth, but a notable P diffusion gradient out of the sediment porewater was identified. In contrast, isotopes in UTL24-TSSD porewater indicated groundwater/ evaporated lake water mixing, while geochemistry showed disrupted P diffusion gradients. We believe storm disruption of shallow sediment and groundwater influence are potential causes for P diffusion differences in the cores

In conclusion, UTL24-DW exhibits P additions by diffusion only while UTL24-TSSD exhibits P addition by diffusion and advection. Further Utah Lake freeze cores will be needed to expand the applicability of these results throughout the lake and determine more precise P fluxes porewater.

Geological Society of America Abstracts with Programs. Vol. 57, No. 5

doi: 10.1130/abs/2025RM-410131

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