Journal article
Spatially referenced Bayesian state-space model of total phosphorus in western Lake Erie
Hydrology and earth system sciences, v 26(8), pp 1993-2017
25 Apr 2022
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
Collecting water quality data across large lakes is often done under regulatory mandate; however, it is difficult to connect nutrient concentration observations to sources of those nutrients and to quantify this relationship. This difficulty arises from the spatial and temporal separation between observations, the impact of hydrodynamic forces, and the cost involved in discrete samples collected aboard vessels. These challenges are typified in Lake Erie, where binational agreements regulate riverine loads of total phosphorus (TP) to address the impacts from annual harmful algal blooms (HABs). While it is known that the Maumee River supplies 50 % of the nutrient load to Lake Erie, the details of how the Maumee River TP load changes Lake Erie TP concentration have not been demonstrated. We developed a hierarchical spatially referenced Bayesian statespace model with an adjacency matrix defined by surface currents. This was applied to a 2 km-by-2 km grid of nodes, to which observed lake and river TP concentrations were joined. The model generated posterior samples describing the unobserved nodes and observed nodes on unobserved days. We quantified the impact plume of the Maumee River by experimentally changing concentration data and tracking the change in in-lake predictions. Our impact plume represents the spatial and temporal variation of how river concentrations correlate with lake concentrations. We used the impact plume to scale the Maumee River spring TP load to an effective Maumee River TP spring load for each node in the lake. By assigning an effective load to each node, the relationship between load and concentration is consistent throughout our sampling locations. A linear model of annual lake node mean TP concentration and effective Maumee River load estimated that, in the absence of the Maumee River load, lake concentrations at the sampled nodes would be 23.1 mu g L-1 (+/- 1.75, 95 % CI, credible interval) and that for each 100 t of spring TP effective load delivered to Lake Erie, mean TP concentrations increase by 11 mu g L-1 (+/- 1, 95 % CI). Our proposed modeling technique allowed us to establish these quantitative connections between Maumee TP load and Lake Erie TP concentrations which otherwise would be masked by the movement of water through space and time.
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Details
- Title
- Spatially referenced Bayesian state-space model of total phosphorus in western Lake Erie
- Creators
- Timothy J. Maguire - NOAA Great Lakes Environmental Research LaboratoryCraig A. Stow - NOAA Great Lakes Environmental Research LaboratoryCasey M. Godwin - NOAA Great Lakes Environmental Research Laboratory
- Publication Details
- Hydrology and earth system sciences, v 26(8), pp 1993-2017
- Publisher
- Copernicus Gesellschaft Mbh
- Number of pages
- 25
- Grant note
- NOAA; National Oceanic Atmospheric Admin (NOAA) - USA NA17OAR4320152 / University of Michigan; University of Michigan System Great Lakes Restoration Initiative
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Environmental Biogeochemistry
- Web of Science ID
- WOS:000786552200001
- Scopus ID
- 2-s2.0-85129785426
- Other Identifier
- 991021903359804721
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- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Geosciences, Multidisciplinary
- Water Resources