Bioavailable phosphorus in humic headwater streams in boreal Sweden
Author
Summary, in English
Bioavailable phosphorus (BAP) concentrations were determined nine times between April and October 2010 in two humic boreal headwater streams draining forest-and mire-dominated catchments. BAP was analyzed in a bioassay in which natural P-limited bacterioplankton grew with natural P as the sole P source. In both streams, approximately 90% of the BAP occurred as dissolved species (passing a 0.2-mu m filter), consisting partly of low-molecular-weight forms (passing a filter with nominal cutoff at 1 kDa) and partly of high-molecular-weight forms (passing a 0.2-mu m filter but not a 1-kDa filter). Concentrations of total dissolved BAP varied between 1 mu g L-1 and 14 mu g L-1, with the highest values in the middle of the summer. Compared to the forest stream, BAP concentrations were generally higher in the mire stream, where it occasionally amounted to nearly 50% of total P. Molybdate reactive phosphorus overestimated BAP considerably. Most of the BAP was in forms other than free orthophosphate. Temporal BAP variations showed no relationships with dissolved organic carbon (C) or iron but were positively related to air temperature and negatively related to the absorbance ratio (a254 : a365) of organic compounds in the water, indicating connections between terrestrial export of BAP and temperature-dependent terrestrial C metabolism. Concentrations of BAP can relieve stream bacteria from P limitation, and a significant share of BAP exported to streams can reach and be used in downstream lakes.
Department/s
Publishing year
2012
Language
English
Pages
1161-1170
Publication/Series
Limnology and Oceanography
Volume
57
Issue
4
Document type
Journal article
Publisher
ASLO
Topic
- Physical Geography
Keywords
- DISSOLVED ORGANIC-CARBON
- BACTERIOPLANKTON PRODUCTION
- TERRESTRIAL SOURCES
- IRON ACCUMULATION
- HUMUS LAYER
- LAKES
- LIMITATION
- PHYTOPLANKTON
- PHOSPHATE
- ALUMINUM
Status
Published
ISBN/ISSN/Other
- ISSN: 1939-5590