Deposition, benthic residence, and resuspension of fine organic particles in a mountain stream

350 210 Stroud Water Research Center

Newbold, J.D., S.A. Thomas, G.W. Minshall, C.E. Cushing, and T. Georgian. 2005. Limnology and Oceanography 50:1571–1580.

doi: 10.4319/lo.2005.50.5.1571


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 14C-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 14C-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.

Give the Gift of Fresh Water

As you give thanks for the gifts in your life, we invite you to give the gift of water. Clean drinking water, good health, happy trout, productive soil, clean air, the simple joys of swimming, boating, fishing — our healthy freshwater ecosystems make these and so many other things possible.

Your donation today will help preserve and protect
the future of fresh water.