Estuarine sediment transport by gravity-driven movement of the nepheloid layer, Long Island Sound

• Published in: Geo-marine letters Vol. 28; no. 4; pp. 245 - 254
• Main Authors: Poppe, L. J., McMullen, K. Y., Williams, S. J., Crocker, J. M., Doran, E. F.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.08.2008; Springer Nature B.V
• Subjects: Brackish; Contaminants; Drainage systems; Earth and Environmental Science; Earth Sciences; Environmental health; Environmental monitoring; Estuaries; Geology; Hypoxia; Marine; Ocean bottom; Ocean floor; Oceanography; Organic sediments; Original; Sediment transport; Sedimentation & deposition; Sonar; Long Island Sound; ANW, USA, Long Island Sound; Marine Transgression; Nepheloid Layer; Central Basin; Western Basin; Glacial Lake
• ISSN: 0276-0460; 1432-1157
• DOI: 10.1007/s00367-008-0118-2

Interpretation of sidescan-sonar imagery provides evidence that down-slope gravity-driven movement of the nepheloid layer constitutes an important mode of transporting sediment into the basins of north-central Long Island Sound, a major US East Coast estuary. In the Western Basin, this transport mechanism has formed dendritic drainage systems characterized by branching patterns of low backscatter on the seafloor that exceed 7.4 km in length and progressively widen down-slope, reaching widths of over 0.6 km at their southern distal ends. Although much smaller, dendritic patterns of similar morphology are also present in the northwestern part of the Central Basin. Because many contaminants display affinities for adsorption onto fine-grained sediments, and because the Sound is affected by seasonal hypoxia, mechanisms and dispersal pathways by which inorganic and organic sediments are remobilized and transported impact the eventual fate of the contaminants and environmental health of the estuary.