McGlathery, K. J.. University of Virginia, 804-982-2137
Berg, P. J.. University of Virginia, firstname.lastname@example.org
POREWATER PROFILES OF DISSOLVED ORGANIC AND INORGANIC N AND P IN VEGETATED MARINE CARBONATE SEDIMENTS
We determined porewater DIN (NH4+, NO3-), DIP, DON, and DOP profiles at two sites in a shallow bay in Bermuda that differed in their distance from the shore and the degree of external nutrient loading. Production or consumption rates within the sediments and fluxes across the sediment-water interface were calculated from the porewater profiles. Both DIP and NH4+ fluxes were directed out of the sediment at both sites; there were no differences in DIP fluxes between the sites, but NH4+ fluxes were highest at the offshore site where plant production was also highest. The NO3- flux was directed into the sediment at the inshore site, probably due to higher denitrification rates where organic matter loading was greater. Porewater concentrations of DOP and DON were generally higher than those of inorganic forms. At both sites, nutrients were released from the sediment to the water column mainly as dissolved organic N and P. Since marine plants can utilize organic forms of N and P and these comprise a large fraction of TDN and TDP, a complete picture of nutrient availability for primary production must include organic as well as inorganic forms of both nutrients.
Day: Thursday, Feb. 4
Location: Sweeney Center