2008 Joint Annual Meeting (5-9 Oct. 2008): Denitrification and the Relative Abundance of nirK and nirS Genes in Tributary Sediments of the Santa Fe River, Florida.
Start | Author Index

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



Monday, 6 October 2008
George R. Brown Convention Center, Exhibit Hall E
Haryun Kim, Andrew V. Ogram and K. Ramesh Reddy, Soil and Water Science, University of Florida, 2169 McCarty Hall A, Gainesville, FL 32611
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 of: Div. S03 Graduate Student Poster Competition (Posters)
See more of: S03 Soil Biology & Biochemistry