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Benthic Nutrient Fluxes

As organic matter contained in sediment decomposes, nutrients once contained in the organic material (e.g., plants debris) are released back into the water. In areas that have accumulated large amounts of sediment organic matter, this process can release large quantities of nutrients into the water contributing to eutrophication (too many nutrients). Eutrophication can lead to algal blooms and ultimately fish kills. This internal source of nutrients can contribute more than 30% of the total input of nutrients to the system and can help to sustain algal blooms when external inputs are lowest, for example during the dry season.

Sediment Oxygen Demand (SOD)

The decomposition of organic matter typically requires oxygen. In areas that have accumulated large amounts of sediment organic matter, decomposition and other chemical processes can quickly use oxygen possibly depleting it from overlying water. If the sediment oxygen demand (SOD) is high, and the sediments or water become anoxic (no oxygen), sediments can release large quantities of nutrients into overlying water. When SOD is low and sediments and the water contain oxygen, sediments can sequester nutrients, helping to remove them from the water. Understanding SOD is essential to understanding nutrient cycling in coastal systems.

Dissolved Oxygen

Dissolved Oxygen (DO) refers to the amount of oxygen, as O2 present in water and is arguably one of the most important indicators of water quality. Too little dissolved oxygen can kill fish and other organisms. As water becomes increasingly polluted with excess nutrients, concentrations of DO become less stable and coastal areas are more frequently experiencing periods of low DO. Although there are sensors measuring DO in the water column, our network is the first to measure DO at the sediment-water interface where it can significantly alter sediment biogeochemistry and nutrient cycling. These data will help to improve lagoon modeling efforts.