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Deposition, benthic residence, and resuspension of fine organic particles in a mountain stream
Author(s) -
Newbold J. Denis,
Thomas Steven A.,
Minshall G. Wayne,
Cushing Colbert E.,
Georgian Ted
Publication year - 2005
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2005.50.5.1571
Subject(s) - deposition (geology) , residence time (fluid dynamics) , water column , benthic zone , particulates , tracer , hydrology (agriculture) , environmental science , environmental chemistry , particle (ecology) , chemistry , oceanography , geology , structural basin , physics , geotechnical engineering , paleontology , organic chemistry , nuclear physics
We estimated deposition and resuspension rates of natural particulate organic matter (POM) in Bloomington Creek, Idaho, a mountain stream flowing at 225 L s ™1 . POM was collected from the water column, fractionated into two size classes— very fine POM (VFPOM, 15‐52 µm) and fine POM (FPOM, 53‐106 µm), and radiolabeled by using 14 C‐dimethylsulfate. The labeled particles in each size class and a conservative tracer were released to the stream in metered pulses and then sampled from the water column at six stations extending 1 km downstream for 4 d. Deposition and resuspension rates were estimated by fitting a one‐dimensional advection‐dispersion model to 14 C‐concentrations measured during and after release. Model‐estimated deposition velocities were 0.12 (0.09‐0.16, 95% confidence interval) and 0.18 (0.10‐0.31) mm s −1 for VFPOM and FPOM, respectively. There was some (~0.05 mm s21) additional short‐term (~20 min) detention of VFPOM and FPOM that may have been related to transient storage. For VFPOM, 34% of deposited particles resuspended after a mean residence time of 13 (6.9‐25) h, and the remainder resuspended with a residence time of 7.5 (2.9‐19) d. For FPOM, these estimates were 17%, 2.4 (1.0‐4.9) h, and 2.6 (1.7‐4.0) d, respectively. The weighted mean residence times and downstream velocities of particle migration were 5.1 d and 150 m d −1 for VFPOM, and 2.2 d and 230 m d −1 for FPOM. The migration velocities suggest that a significant fraction of particles exported from headwater streams travel long distances and can reach larger riverine or marine environments before mineralization.