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The sediment grain size major mode values are visually estimated from the 

 REMOTS® photographs by overlaying a grain size comparator that is at the same scale. 

 For REMOTS® analysis, sediment grain size major mode is expressed in phi units. This 

 measurement represents the dominant grain size in the entire frame (field of view) and may 

 not distinguish layers of coarser or finer material. However, the results presented in this 

 report for 1992 and 1997 explicitly record distinct layers separately from major mode. A 

 grain size scale for sediments has been provided in Table 2-3, to allow easy conversion 

 between phi units, millimeters, and standard sieve sizes. 



The REMOTS sediment profile camera consists of an optical prism, which 

 penetrates the bottom under a static driving force imparted by its own weight. The 

 penetration depth into the bottom depends on the force exerted by the optical prism and the 

 bearing strength of the sediment. If the weight of the camera prism is held constant, the 

 change in penetration depth over a surveyed site will reflect changes in geotechnical 

 properties of the bottom. In this sense, the camera prism acts as a static-load 

 penetrometer. The depth of penetration of the optical prism into the bottom can be a 

 useful parameter, because dredged and capped materials often will have different shear 

 strengths and bearing capacities. 



Small-scale surface boundary roughness is the amount of surface relief at the 

 sediment- water interface, and is calculated by measuring the vertical distance between the 

 high and low points of the interface in each sediment-profile photograph. Boundary 

 roughness can be categorized as biological, physical, or indeterminate. Biological 

 disturbances, typically the result of macrofaunal activity, usually result in only a small 

 increase is boundary roughness (< 1 cm). A mature and undisturbed benthic environment 

 tends to have biological boundary roughness. Physical disturbances can be anthropogenic 

 in origin (for example, by bottom trawling or dredged material disposal) or attributed to 

 natural processes such as wave and current motion. 



The Apparent Redox Potential Discontinuity (RPD) depth is the boundary between 

 oxygenated sediment and the underlying hypoxic or anoxic sediment. The RPD depth is a 

 sensitive indicator of the biological mixing depth, infaunal successional status, and within- 

 station patchiness (Revelas et al. 1987). The RPD is determined by measuring the 

 thickness of the high reflectance sediment layer at the sediment-water interface formed by 

 light-colored oxygenated or oxidized sediment. 



Successional stage mapping is based upon the hypothesis that organism-sediment 

 interactions follow a predictable successional sequence after a major seafloor disturbance 

 (Rhoads and Germano 1986). A disturbance can be any type of event that induces seafloor 



Monitoring Cruise at the New London Disposal Site, 1992 - 1998 



