Document Type
Thesis
Abstract
The estuarine turbidity maximum (ETM) of the upper Chesapeake Bay is an area in which details of the processes that trap and maintain sediment in suspension are not well understood. This study examines data from three cruises to the area in May, July, and October 2001. While on the cruises, bed sediment sampling was conducted in an attempt to better understand (i) along-channel patterns in bed characteristics and (ii) if a relationship exists between bed properties and the turbidity of the overlying water column. Laboratory methods used to analyze bed sediment included Eh, organic content, water content, grain size, and beryllium-7 analyses. Sediment properties in the northern Bay were found to be associated with the general location of the ETM, based on areas of increased turbidity. Eh values in all three months became increasingly positive to the north along the channel, reaching a maximum in the vicinity of the center of the ETM. In some instances, organic content did increase where Eh values were more negative, and decreases where Eh values were more positive. Therefore, organic content may have affected Eh. Nonetheless, variations in Eh reasonably tracked seasonal variation in the ETM, with both the Eh distribution and the ETM moving southward from May to July, and both becoming less pronounced in October. Water content and presence of beryllium-7 at depth in the sediment samples increased to the north in May and July, but trends were less clear in October. Grain size did not decrease to the north. A considerable amount of sand was present in the northernmost Bay in all three months, consistent with the proximity to the Susquehanna delta. The patterns of Eh, water content, and beryllium-7 all suggest that the location of the ETM in the northern Bay is associated with resuspension of recently deposited, easy to resuspend muds, with Eh providing the strongest indicator. Thus, a clear association does exist between bay bed characteristics and turbidity in the water column.
Date Awarded
2002
Department
Geology
Advisor 1
Carl Friedrichs
Advisor 2
Heather MacDonald
Recommended Citation
Ellis, Lynsey Erin, "Seabed Conditions in the Estuarine Turbidity Maximum Region of the Chesapeake Bay" (2002). Geology Senior Theses. William & Mary. Paper 96.
https://scholarworks.wm.edu/geologyseniors/96
