Accelerated Settling of Marine Particulate Matter by 'Marine Snow' Aggregates.

• Main Author: Asper,Vernon L
• Other Authors: WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
• Format: Text
• Language: English
• Published: 1986
• Subjects: Biological Oceanography; Physical and Dynamic Oceanography; *SUSPENDED SEDIMENTS; *SEDIMENTATION; FLUX(RATE); INTERCEPTION; TIME SERIES ANALYSIS; THESES; DEPTH; SEDIMENT TRANSPORT; VERTICAL ORIENTATION; DELAY; DECOMPOSITION; SEA WATER; OCEAN MODELS; CIRCULATION; OCEAN BOTTOM; NORTH PACIFIC OCEAN; OPEN WATER; BLACK SEA; FLOCCULATION; SINKING; Panama Basin; Marine Snow Aggregates; Abundance; Sinking rates; Resuspended sediments; *Aggregates; Pacific; North Atlantic
• Online Access: http://www.dtic.mil/docs/citations/ADA166868; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA166868

Samples from time-series sediment traps deployed in three distinct oecanographic settings (North Pacific, Panama Basin, and Black Sea) provide strong evidence for rapid settling of marine particles by aggregates. Particle water column residence times were determined by measuring the time lag between interception of a flux event in a shallow trap and interception of the same event in a deeper trap at the same site. Effective sinking speeds were determined by dividing the vertical offset of the traps (meters) by the interception lag time (days). At station Papa in the North Pacific, all particles settle at 175 m/day, regardless of composition, indicating that all types of material may be settling in common packages. Evidence from the other two sites shows the particle transport may be vertical, lateral, or a combination of directions with much of the Black Sea flux signal being dominated by lateral input. In order to ascertain whether 'marine snow' aggregates represent viable transport packages, surveys were conducted of the abundance of these aggregates at several stations in the eastern North Atlantic and Panama Basin. Marine snow aggregates were found in concentration ranging from approx. 1 cu mm/l to more than 500 cu mm/l. In open ocean environments, abundances are higher near the surface (production) and decline with depth (decomposition). However, in areas near sources of deep input of resuspended material, concentrations reach mid-water maxima, reflecting lateral transport. A model is proposed to relate the observed aggregate abundances, time series sediment flux and inferred circulation. Sponsored in part by Grants NSF OCE83-09024, NSF-OCE84-17106 and NSF-DPP85-01152.