A Comprehensive Estuarine Dissolved Organic Carbon Budget Using an Enhanced Biogeochemical Model
J. Blake Clark, Wen Long, Raleigh R. Hood
Abstract
Abstract Complicated biogeochemical cycling and differential organic matter reactivity make quantifying the relative contribution of a given source of organic carbon to the standing stock within an estuary difficult. Here, a new model of tidal marsh‐estuary organic carbon cycling is presented for the Rhode River, MD, a well‐studied tributary of the Chesapeake Bay, USA. A dissolved organic carbon (DOC) budget was estimated by summing the source and sink terms and the advection of water within the tributary. 13.1% and 15.3% of the total DOC input to the Rhode River entered from the marsh and the watershed, respectively, and 52.6% was derived from phytoplankton production. Extrapolating to the entire year, 35.5 Mg of DOC is exported to the main stem of Chesapeake Bay annually, which accounts for 12.3% of the total allochthonous and autochthonous inputs to the estuary. Removing the modeled marsh at the head of the Rhode River decreased export of DOC to the main stem by 39.2%, and up to 56% of the estuarine DOC standing stock can be attributed to the marsh. The model described here can be used across temperate estuarine systems and provides a new methodology for quantifying the amount of DOC that can be attributed to or lost by specific source and sink pathways.