583-6 Denitrification and the Relative Abundance of nirK and nirS Genes in Tributary Sediments of the Santa Fe River, Florida.

Poster Number 476

See more from this Division: S03 Soil Biology & Biochemistry
See more from this Session: Div. S03 Graduate Student Poster Competition (Posters)

Monday, 6 October 2008
George R. Brown Convention Center, Exhibit Hall E

Ha Ryun Kim, Andrew Ogram and K. Ramesh Reddy, Soil and Water Science, University of Florida, Gainesville, FL
Abstract:
Intensive agriculture and fertilizer use have increased nitrogen loads to adjacent aquatic ecosystems. However, buffer systems such as riparian, tributaries and floodplains around agriculture ecosystems can decrease nitrogen concentrations through denitrification. We investigated the role denitrification in tributary sediments of the western Santa Fe River watershed, Florida, in processing nitrogen loads from adjacent land use activities (Nursery and Ranching). In sediments with a range of organic matter contents, N fertilization increased NO3- concentrations in the tributary sediment with low organic matter (less than 1% soil organic carbon determined by loss on ignition). However, the system impacted by nursery activities exhibited lower denitrifying enzyme activity (DEA) than the system impacted by ranch activity with relatively high organic matter (more than 1% soil organic carbon determined by loss on ignition). In low organic matter tributary sediments, DEA was low in both land activities. In addition, denitrification activity exhibited a positive relationship with liable organic carbon, indicating that available carbon may be a main factor controlling denitrification. The high organic matter system in both tributaries contained higher concentrations of NH4+, TOC, and MBC, and exhibited higher DEA than the relatively low organic matter sediments from either system. All systems yielded nirS (encoding nitrite reductase) PCR products, with higher intensity PCR bands from high organic matter sediments than from low organic matter sediments. However, relatively few nirK (encoding alternate nitrite reductase) PCR amplification products were visible, and only in those impacted by ranching activities.

See more from this Division: S03 Soil Biology & Biochemistry
See more from this Session: Div. S03 Graduate Student Poster Competition (Posters)