Implementing high-frequency nitrate quantification in water quality monitoring in the Chandeleur Sound of Pontchartrain Basin, Louisiana, USA

The Louisiana coast is a model for regional climate change effects, due to frequent severe weather, increasing freshwater inundation, and elevated sea surface temperatures. Other anthropogenic pressures in southeastern coastal Louisiana are constituted by proximity to the New Orleans metropolitan area, Lake Pontchartrain and Mississippi River outflow, and heavy uses for Gulf industries. The TriOS OPUS, an in situ optical nitrate (N-NO3) sensor, was deployed in July 2024 to Chandeleur Sound, a shallow estuary in Pontchartrain Basin, Louisiana near the Biloxi Wildlife Management Area. The deployment site represents a relevant study area for monitoring nutrient dynamics in an estuarine ecosystem under a changing climate and anthropogenic forcings. The TriOS OPUS has been deployed with a YSI Exo3 sonde from July 2024 to present. The OPUS measures concentrations of nitrate, total suspended solids, and a nonspecific indicator for dissolved organic matter, SAC254, every 15 minutes. The Exo3 sonde measures chlorophyll-a, dissolved oxygen, temperature, salinity, and turbidity. Discrete reference nutrient samples are collected monthly. This presentation will highlight the effects of ephemeral storm events captured by high-frequency nitrate quantification which are missed by traditional, discrete sampling. Storm-driven disturbances will be compared with pre-storm conditions to characterize short-term water quality response. Nitrate stimulation events will be discussed in context of event drivers, biological response (via chlorophyll-a), and trends in other water quality parameters.

Presentation Preference: Poster

Primary Presenter: Emily Piwowarski, University of Louisiana at Lafayette (emily.piwowarski@louisiana.edu)

Authors:

Emily Piwowarski, University of Louisiana at Lafayette  (emily.piwowarski@louisiana.edu)

Beth Stauffer, University of Louisiana at Lafayette  (beth.stauffer@louisiana.edu)