sediment

Repeated erosion of sediments with biofilms from Rowley River mud flats, year 2012, Rowley, MA

Abstract: 

This study aims to explore the interplay between biofilms and erodability of cohesive sediments. Erosion experiments were run in four laboratory annular flumes with natural sediments. Mud from the Rowley River mudflats was taken at low tide and then placed in flumes. Two of the flumes were bleach to prevent biota, while the other two were allowed to grow; nutrients were also added to the flumes. On different intervals, the flumes were eroded and the amount of erosion and velocity of the flow were measured. Additionally, each day biofilm growth was measured using Pulse-Amplitude Modulation (PAM) Underwater Fluorometry. Reported here are 10 minute averages of shear stress (derived from velocity) and suspended sediment (uncalibrated, in NTUs) along with PAM measurements. The complete dataset is available upon request via .mat files, but the dataset is quite large (kendallv@bu.edu or pie_im@mbl.edu).

Core Areas: 

Data set ID: 

347

Keywords: 

Short name: 

STP-RO-FlumeSedimentErosion

Purpose: 

 

Data sources: 

STP-RO-FlumeSedimentErosion_csv
STP-RO-FlumeSedimentErosion_xls

Methods: 

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

Maintenance: 

Data collection complete
Version 01: August 13, 2014, data and metadata comply with importation to Drupal and LTER PASTA. Used MarcrosExportEML_HTML (working)pie_excel2007.xlsm 6/30/14 11:33 AM for QA/QC to EML 2.1.0

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