Benthic fluxes of fluorescent dissolved organic material, salt and heat measured by multiple-sensor aquatic eddy covariance

Irene Hu and Harold Hemond

https://doi.org/10.3390/

Aquatic eddy covariance (AEC) is an in situ technique for measuring fluxes in marine and freshwater systems based on the covariance of velocity and concentration measurements. Here, development of a fast multiple-channel sensor (FACT) enables the use of AEC for measurement of benthic fluxes of fluorescent dissolved organic material, salt, and heat at three distinct sites in Massachusetts, USA, including the Connecticut River, the Concord River, and Upper Mystic Lake. Simultaneous measurement of several fluxes expands the utility of AEC as a biogeochemical tool while enabling checks for mutual consistency among data channels.

Figure 1 (left). Eddy flux instrument mounted on benthic lander. Communication buoy, shown strapped to the lander for very shallow deployments, floats free for deeper deployments. (Top inset) FACT sensor head including optical fibers, conductivity electrodes, and thermistor. (Bottom inset) FACT sensing head shown with jig for aligning sensing volumes.

Figure 2 (right). Location map of three field sites at which the eddy flux instrument was deployed, with current rose of water velocities in horizontal plane measured during EC deployment. Current roses indicate direction that current is traveling towards. Star indicates location of instrument deployment.