Sediment was collected from the mudflats on the Rowley River, was sieved through a #10 sieve, and then was frozen at -18 C for 12 hours. Sediment was then thawed and placed in flumes. Flumes had lights over them with a 24 hour light/dark cycle. A water column of saline water was placed over the sediment. Flumes 1 and 2 were bleached to attempt to kill remaining biota. Nutrients were added daily to each flume. For description of the flume, see Valentine et al. (2014).
For erosion experiments, a propeller was placed in the flume. The propeller started at a low velocity and increased velocity every 10 minutes for a total of 80 minutes. Then the propeller was removed from the flume and the sediment was allowed to settle. During erosion experiments, an Acoustic Doppler Velocimeter and Optical Backscatter Sensor were deployed in the flume to measure velocity and suspended sediment. Velocity was used to calculate shear stress using the Reynolds shear stress equation. Daily, 10 Pulse-Amplitude Modulation (PAM) Underwater Fluorometer measurements were taken in the flumes and were calibrated to chlorophyll a samples taken from the flumes.
For the data uploaded here, shear stress and suspended sediment are reported as 10 minutes averages. Raw high frequency data as .mat files are available upon request (kendallv@bu.edu or pie_im@mbl.edu)
Paper from this experiment outlines all of the procedures - citation below:
Valentine, K., Mariotti, G., and Fagherazzi, S. (2014). Repeated erosion of cohesive sediments with biofilms. Advances in Geosciences, 39, 9-14. doi:10.5194/adgeo-39-9-2014
Additional parameter explanation
Date - Date erosion took place
Flume - Four flumes were used. Flumes 1 and 3 were eroded every ~12 days and 2 and 4 were eroded every ~2 days. Flumes 1 and 2 were bleached and 3 and 4 were not.
Time - Time interval within the erosion over which the variables were averaged. Each erosion was 80 minutes and averages were taken every 10 minutes.
Shear Stress - Shear stress (average over 10 minute intervals) calculated using Reynolds shear stress using velocity measurements taken using an ADV at 32 Hz.
Suspended Sediment - Uncallibrated suspended sediment values from an Optical Backscatter Sensor, averaged over 10 minute intervals. Samples were taken at 1 Hz.
PAM 1 to PAM 10 - Ten measurements of Chl. a were taken using Pulse Amplitude Modulation (PAM) in each flume each day.
Chl a - acetone extracted chlorophyll a measurements used to calibrate PAM measurements
Pheophytin - acetone extracted pheophytin measurements used to calibrate PAM measurements
Protocol Handbook for NICE - Nitrogen Cycling in Estuaries: A Project under the EU Research Programme: Marine Science and Technology (MAST III) (Silkeborg, Denmark: National Environmental Research Institute).
http://www2.dmu.dk/lakeandestuarineecology/nice/nice_handbook.pdf
