Marine radiocarbon reservoir corrections ({increment}R) for Chesapeake Bay and the Middle Atlantic Coast of North America

Radiocarbon dates from known age, pre-bomb eastern oyster (Crassostrea virginica) shells provide local marine reservoir corrections ({increment}R) for Chesapeake Bay and the Middle Atlantic coastal area of eastern North America. These data suggest subregional variability in {increment}R, ranging from 148±46 ¹⁴Cyr on the Potomac River to -109±38 ¹⁴Cyr at Swan Point, Maryland. The {increment}R weighted mean for the Chesapeake's Western Shore (129±22 ¹⁴Cyr) is substantially higher than the Eastern Shore (-88±23 ¹⁴Cyr), with outer Atlantic Coast samples falling between these values (106±46 and 2±46 ¹⁴Cyr). These differences may result from a combination of factors, including ¹⁴C-depleted freshwater that enters the bay from some if its drainages, ¹⁴C-depleted seawater that enters the bay at its mouth, and/or biological carbon recycling. We advocate using different subregional {increment}R corrections when calibrating ¹⁴C dates on aquatic specimens from the Chesapeake Bay and coastal Middle Atlantic region of North America.