| Abstract: | Nitrate reduction and denitrification were measured in swamp forest streams draining lowland rain forest on Costa Rica‘s Atlantic slope foothills using the C2H2-block assay and sediment-water nutrient fluxes. Denitrification assays using the C2H2-block technique indicated that the full suite of denitrifying enzymes were present in the sediment but that only a small fraction of the functional activity could be expressed without adding NO3/-. Under optimal conditions, denitrification enzyme activity averaged 15 nmoles cm-3 sediment h-1. Areal NO3/- reduction rates measured from NO3/- loss in the overlying water of sediment- water flux chambers ranged from 65 to 470 umoles m-2 h-1. Oxygen loss rates accompanying NO3/-depletion averaged 750 umoles m-2 h-1. Corrected for denitrification of NO3/- oxidized from NH4/+ in the sediment, gross NO3/- reduction rates increase by 130 umoles m-2 h-1, indicating nitrification may be the predominant source of NO3/- for NO3/- reduction in swamp forest stream sediments. Under field conditions approximately 80% of the increase in inorganic N mass along a 1250-m reach of the Salto River was in the form of NO3/- with the balance NH4/+. Scrutiny of potential inorganic N sources suggested that mineralized N released from the streambed was a major source of the inorganic N increase. Despite significant NO3/- reduction potential, swamp forest stream sediments appear to be a source of inorganic N to downstream communities. |
| Genre: | Article |
| ProdID: | 70018110 |
| Citation Author: | Duff, J. H.; Pringle, C. M.; Triska, F. J. |
| Citation Contributing Office: | |
| Citation Datum: | |
| Citation Day: | |
| Citation Edition: | |
| Citation Editor: | |
| Citation End Page: | 196 |
| Citation Issue: | 3 |
| Citation Keywords: | |
| Citation Language: | English |
| Citation Larger Work Title: | Biogeochemistry |
| Citation LatN: | |
| Citation LatS: | |
| Citation LonE: | |
| Citation LonW: | |
| Citation Month: | |
| Citation No Pagination: | |
| Citation Number Of Pages: | 18 |
| Citation Online Only Flag: | |
| Citation Phsyical Description: | |
| Citation Projection: | |
| Citation Public Comments: | |
| Citation Publisher: | |
| Citation Series: | |
| Citation Series Code: | |
| Citation Series Number: | |
| Citation Search Results Text: | Nitrate reduction in sediments of lowland tropical streams draining swamp forest in Costa Rica: An ecosystem perspective; 1996; Article; Journal; Biogeochemistry; Duff, J. H.; Pringle, C. M.; Triska, F. J. |
| Citation Start Page: | 179 |
| Citation Volume: | 33 |
| Citation Year: | 1996 |
| Type: | citation/reference |
| Text: | Nitrate reduction in sediments of lowland tropical streams draining swamp forest in Costa Rica: An ecosystem perspective; 1996; Article; Journal; Biogeochemistry; Duff, J. H.; Pringle, C. M.; Triska, F. J. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Mon, 1 Jan 1996 00:00 -0600 |
| Publisher: | |
