Burdige, D. J. Old Dominion University, dburdige@odu.edu
, . J. ,

 
THE COMPOSITION AND REACTIVITY OF DISSOLVED ORGANIC MATTER (DOM) IN MARINE SEDIMENT PORE WATERS
 
Knowledge about the composition and reactivity of DOM in marine sediment pore waters is important for several reasons; this material is an intermediate in sediment carbon remineralization, and may also play a role in sediment carbon preservation. For these reasons, in recent years we have carried out studies in contrasting estuarine and continental margin sediments of: concentrations and benthic fluxes of bulk DOC and DON; DOM molecular weight distributions; carbohydrate content; DOM absorbance and fluorescence. We have observed that the majority of the DOM accumulating in pore waters is relatively low molecular weight material (less than approx. 3 kDa), and predominantly shows humic-like fluorescence. Production of DOM with protein like fluorescence is also seen in sediments, although there does not appear to be significant net accumulation of this material. There is an inverse relationship between the molecular weight and total carbohydrate content of pore water DOM, suggesting that chemically recognizable carbohydrates may be preferentially found in the high molecular weight fraction of DOM. These (and all our other) observations will be discussed in the context of a conceptual model for pore water reactivity in sediments (Burdige and Gardner, Mar. Chem. 62:45, 1998) which combines traditional views of sediment carbon remineralization and recent observations regarding size-reactivity relationships for water column DOM.
 
Day: Tuesday, Feb. 2
Time: 12:00 - 12:15pm
Location: Eldorado Hotel
 
Code: SS34TU1200E