Abstract
Biophysical cohesion, introduced predominantly by Extracellular Polymeric Substances (EPS) during mineral flocculation in subaqueous environments, plays important role in morphodynamics, biogeochemical cycles and ecosystem processes. However, the mechanism of how EPS functioning with cohesive particles and affects settling behaviors remain poorly understood. We measure initial flocculation rate, floc size and settling velocity of mineral and artificial EPS (Xanthan gum) mixtures. Combining results from these and previous studies demonstrate coherent intensification of EPS-related flocculation compare with those of pure mineral and oil-mineral mixtures. Importantly, the presence of EPS fundamentally changes floc structure and reduces variability of settling velocity. Measured data shows that ratios of microfloc and macrofloc settling velocity for pure mineral flocs is 3.9 but greatly reduced to a lowest value of 1.6 due to biological EPS addition. The low variability of settling velocity due to EPS participation explains the seemingly inconsistent results previously observed between field and laboratory studies.
| Original language | English |
|---|---|
| Article number | 138 |
| Journal | Communications Earth and Environment |
| Volume | 4 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 2023 |
Funding
This research was made possible by the National Science Foundation (OCE-1924532) and in part by a grant from the Gulf of Mexico Research Initiative to support CSOMIO (Consortium for Simulation of Oil-Microbial Interactions in the Ocean) (Grant no. SA18−10). AM’s contribution toward this research was also partly supported by the National Science Foundation grant OCE−1736668. LY’s contribution was also partly supported by Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) (Grant No. 311020003) and the National Natural Science Foundation of China (Grant no. 42106160).