TY - JOUR
T1 - Biological effects on flocculation of fine-grained suspended sediment in natural seawater
AU - Skinnebach, Kristoffer Hofer
AU - Fruergaard, Mikkel
AU - Andersen, Thorbjorn Joest
PY - 2019/11/15
Y1 - 2019/11/15
N2 - The flocculation process is ever occurring in the marine and estuarine environment, and better knowledge of the biological influence as a governing factor is central to improve the understanding and modelling of the horizontal distribution of sediments. In this study we performed a series of laboratory experiments with fine-grained sediments from Sermilik Fjord and Young Sound, situated in Southeast and Northeast Greenland, respectively. The sediment was suspended in natural low-turbidity seawater, filtered seawater and NaCl-supplemented tap water to quantify the isolated effect of particulate organic material (POM) and dissolved substances on flocculation of fine-grained cohesive sediment. A high-resolution camera system (PCam) was applied to observe the effects, and the images and videos were processed in MatLab. The results showed a significantly enhanced flocculation from the presence of POM with larger floc sizes and higher settling velocities compared to flocs formed in seawater filtered with a retention diameter of 0.7 μm. The influences of the remaining dissolved substances, however, led to an enhancement of the flocculation and mass settling of particles compared to those of the control experiments (NaCl-supplemented tap water). The comparison of flocculation potential of sediments from the two different geographic locations in Greenland showed large differences in size and effective density of the flocculated particles, likely caused by the observed differences in texture and organic content of the sediments.
AB - The flocculation process is ever occurring in the marine and estuarine environment, and better knowledge of the biological influence as a governing factor is central to improve the understanding and modelling of the horizontal distribution of sediments. In this study we performed a series of laboratory experiments with fine-grained sediments from Sermilik Fjord and Young Sound, situated in Southeast and Northeast Greenland, respectively. The sediment was suspended in natural low-turbidity seawater, filtered seawater and NaCl-supplemented tap water to quantify the isolated effect of particulate organic material (POM) and dissolved substances on flocculation of fine-grained cohesive sediment. A high-resolution camera system (PCam) was applied to observe the effects, and the images and videos were processed in MatLab. The results showed a significantly enhanced flocculation from the presence of POM with larger floc sizes and higher settling velocities compared to flocs formed in seawater filtered with a retention diameter of 0.7 μm. The influences of the remaining dissolved substances, however, led to an enhancement of the flocculation and mass settling of particles compared to those of the control experiments (NaCl-supplemented tap water). The comparison of flocculation potential of sediments from the two different geographic locations in Greenland showed large differences in size and effective density of the flocculated particles, likely caused by the observed differences in texture and organic content of the sediments.
KW - Flocculation
KW - Cohesive sediment dynamics
KW - Settling experiments
KW - Particulate organic matter
KW - PCam
U2 - 10.1016/j.ecss.2019.106395
DO - 10.1016/j.ecss.2019.106395
M3 - Journal article
SN - 0272-7714
VL - 228
JO - Estuarine, Coastal and Shelf Science
JF - Estuarine, Coastal and Shelf Science
M1 - 106395
ER -
