THE FLUX AND COMPOSITION OF RESUSPENDED SEDIMENT IN LYDONIA 

 CANYON: IMPLICATIONS FOR POLLUTANT SCAVENGING 



Dr. Michael H. Bothner 



U. S. Geological Survey 



Woods Hole, MA 



One of the objectives of the U.S. Geological Survey's sediment 

 geochemistry studies in Lydonia Canyon and on the adjacent continental shelf 

 and slope was to determine the relative potential for sediments to accumulate 

 contaminants. The analyses of bottom and suspended sediments have provided 

 four lines of evidence that suggest that the axis of Lydonia Canyon has a 

 higher potential for contaminant accumulation than the surrounding areas do. 



The evidence supporting this conclusion includes the following: 



■ The head and axes of Lydonia (and Oceanographer) Canyon has much 

 higher fluxes of resuspended sediment than the adjacent shelf or 

 slope. This resuspension activity provides more opportunity for 

 particles to adsorb dissolved contaminants from seawater. 



■ The head of Lydonia Canyon is an area of active sediment accumulation. 

 (This is based on carbon-14 dating of piston cores.) Therefore, some 

 of the sediment that is recycled into the water column by resuspension 

 is eventually buried in the bottom sediments by subsequent deposition. 



■ Enhanced scavenging of dissolved contaminants is suggested by the 

 inventories of sediment-reactive isotopes lead-210 and plutonium-239, 

 -240, which are higher in the sediments of the axis of Lydonia Canyon 

 than in sediment from areas of comparable depth on the continental 

 slope. 



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