Date of Award


Document Type


Degree Name

Master of Science in Coastal Marine and Wetland Studies


Coastal and Marine Systems Science

First Advisor

Richard N. Peterson

Second Advisor

Willard S. Moore

Third Advisor

Richard F. Viso

Additional Advisors

Susan M. Libes; Paul T. Gayes


Long Bay, South Carolina has experienced hypoxic conditions (<2mg/L dissolved oxygen) in the nearshore environment, not fully attributed to traditional formation mechanisms. Past research suggested physical, biological, and/or anthropogenic influences on low dissolved oxygen levels. This project aimed to determine the contribution of submarine groundwater discharge (SGD) to hypoxia formation. We measured activities of 222Rnxs, 224Raxs, 223Ra, 228Ra, and 226Ra (3.8d, 3.6d, 11.5d, 5.8yr, 1600yr half-lives, respectively) in nearshore bottom waters from April 2012 through April 2013. Radium activities observed during a hypoxic event on 16-Aug-2012 were up to an order of magnitude higher than those seen during oxic conditions and the highest ever observed in the open ocean, to our knowledge. We determined that a hypoxic water mass, comprised heavily of offshore anoxic SGD, migrated inshore due to physical conditions constraining mixing over a two week time period. High groundwater content suggests that observed hypoxic conditions in nearshore Long Bay may be independent of biological influence once offshore SGD occurs.

Included in

Oceanography Commons