Nitrate reduction in sediments of lowland tropical streams draining swamp forest in Costa Rica: An ecosystem perspective
Biogeochemistry
By: J.H. Duff, C. M. Pringle, and F.J. Triska
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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.
Suggested Citation
Duff, J., Pringle, C.M., Triska, F., 1996, Nitrate reduction in sediments of lowland tropical streams draining swamp forest in Costa Rica: An ecosystem perspective: Biogeochemistry, v. 33, no. 3, p. 179-196, https://doi.org/10.1007/BF02181071.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Nitrate reduction in sediments of lowland tropical streams draining swamp forest in Costa Rica: An ecosystem perspective |
| Series title | Biogeochemistry |
| DOI | 10.1007/BF02181071 |
| Volume | 33 |
| Issue | 3 |
| Year Published | 1996 |
| Language | English |
| Publisher | Springer |
| Contributing office(s) | Toxic Substances Hydrology Program |
| Description | 18 p. |
| First page | 179 |
| Last page | 196 |