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Sediment-water 02 dynamics and feedbacks to sediment oxic, suboxic, and anoxic processes on the Louisiana shelf
Citation:
Lehrter, J., R. Devereux, M. Murrell, D. Beddick, D. Yates, B. Jarvis, AND B. Herchenroder. Sediment-water 02 dynamics and feedbacks to sediment oxic, suboxic, and anoxic processes on the Louisiana shelf. Presented at ASLO 2013 Aquatic Sciences Meeting, February 17 - 22, 2013.
Impact/Purpose:
The objective is to develop a realistic sediment diageneses modeling scheme that can be implemented in a 3-D hypoxia model
Description:
The Mississippi and Atchafalaya Rivers annually discharge 674 km3 of freshwater, 86 x 109 moles nitrogen, 5 x 109 moles phosphorus, and 325 x 109 moles organic carbon to the Louisiana shelf. The seasonal input and transport of these materials causes large temporal and spatial variability in sub-pycnocline O2 concentrations, which are often hypoxic (< 2 mg/L). Bottom-water oxygen dynamics are in turn coupled to sediment processes such as bioturbation/bioirrigation, coupled nitrification-denitrification, and iron and sulfate reduction. To investigate the role of sediment processes on O2 concentration on the Lousiana shelf, we implemented a 1-D vertical profile (‘method of lines’) sediment biogeochemistry model constrained by detailed sediment profile chemistries and biogeochemical rate measurements in oxic, suboxic, and anoxic zones within the sediments. Such feedbacks are generally not captured in 3-D ocean ecosystem models because of limited datasets for model evaluations and the computational cost of implementing numerically intensive high resolution grids. Based on our results, we explore the challenges of implementing realistic sediment schemes in 3-D hypoxia models for the Louisiana shelf.