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Application of a one-dimensional model to explore the drivers and lability of carbon in the northern Gulf of Mexico
Citation:
Pauer, J., P. DePetro, A. Anstead, AND J. Lehrter. Application of a one-dimensional model to explore the drivers and lability of carbon in the northern Gulf of Mexico. ECOLOGICAL MODELLING. Elsevier Science BV, Amsterdam, Netherlands, 294:59-70, (2014).
Impact/Purpose:
A one-dimensional water quality model, Gulf of Mexico Dissolved Oxygen Model was developed to simulate phytoplankton, carbon, nutrients, and dissolved oxygen in Gulf of Mexico. The model was calibrated and corroborated against a comprehensive set of field observations and process measurements. This work supports the Mississippi River/Gulf of Mexico Watershed Nutrient (Hypoxia) Task Force and the Gulf Hypoxia Action Plan. The model provides insight into the lability and transport of organic carbon in the shelf. The results also show the interplay between nutrients and light in regulating phytoplankton production and carbon vertical export, which are important when predicting the location and extent of hypoxia in the Gulf of Mexico. The model was used to determine the fate and lability of dissolved organic carbon (DOC) at selected locations within the shelf area of the Gulf of Mexico. Consistent with previous observations, the model suggests that autochthonous production of DOC was insufficient to offset the respiratory demand from bacterial processes. The transport of carbon from high production areas close to the river plumes likely supplied a part of the respiratory demand of the water column. Sensitivity analysis was performed to investigate the impact of different light and nutrient regimes on the phytoplankton production rates, organic carbon and vertical export at selective locations. The resutls showed that primary production and the resulting DOC and carbon vertical export was very sensitive to light, especially near the Mississippi River.
Description:
A one-dimensional water quality model, Gulf of Mexico Dissolved Oxygen Model (GoMDOM-1D), was developed to simulate phytoplankton, carbon, nutrients, and dissolved oxygen in Gulf of Mexico. The model was calibrated and corroborated against a comprehensive set of field observations and process measurements. Model results fit measured nutrients, dissolved oxygen, and phytoplankton concentrations well, but the model was unable to sustain dissolved organic carbon and water column respiration at measured levels. The decline in modeled respiration supports the notion that autochthonous production of DOC was insufficient to offset the respiratory demand from bacterial processes. Transport of carbon from high production areas close to the river plumes likely supplied a part of the respiratory demand of the water column. DOC in the study area on the Louisiana Shelf was very labile (more than 60%) with the highest lability during the month of June, and decreased lability in April. Primary production at the study locations was mainly nitrogen limited, although phosphorus limitation was found in the surface layers for the areas most impacted by the Mississippi River plume. Sensitivity analysis showed that primary production and the resulting DOC was very sensitive to light, especially near the Mississippi River. The model also provided some insights into the interplay between nutrients and light in regulating phytoplankton production and carbon vertical export, which are important when predicting the location and extent of hypoxia in the Gulf of Mexico.
