Core Samplers
McNeil Sediment Core Sampler
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The McNeil Core Sampler consists of a cylinder that defines the
portion of the streambed to be sampled and an attached basin that
is used to store the collected sediments and trap the suspended
fines. The McNeil core sampler is constructed out of stainless
steel and can be modified to fit most sampling situations. The
sampler is worked into the channel substrate, and the encased
sediment core is dug out by hand and deposited in a built-in
basin. When all sediments have been removed to the level of the
lip of the core tube, a cap is placed over the tube to prevent
water and the collected sediments from escaping when the tube is
lifted out of the water. Those suspended sediments in the tube
below the cap are lost, but this loss is generally an
insignificant percentage of the total sample.
The sediments and water collected are strained through a series
of sieves to determine the particle size distribution, percent
fines, or geometric mean diameter of the distribution. The
sediments collected can be analyzed in the laboratory using the
"dry" method or in the field using the "wet" method. Tube is 4"
dia. x 8" long. Basin is 12" dia. x 18" tall.
406-012 McNeil Core
Sampler 16 lbs.
USFS Freeze Core Bed Material Sampler
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The freeze-core method of bed material sampling uses a
three-tube device, driven into the streambed, through which a
compressed gas (C02) is allowed to expand. The temperature
reduction associated with the expanding gas freezes the
interstitial water in the bed adjacent to the tubes, allowing the
frozen core of relatively undisturbed sediment and organic
material to be removed from the streambed. The freeze methods
allow collection of eggs and alevins, at any stage of development.
The methods will function at most air or water temperatures or
stream depths, and will allow analysis of horizontal and vertical
locations of eggs and alevins.
A major advantage of the freeze-core sampler is that it
provides opportunity for vertical stratification of substrate
cores. Particle-size distributions of the freeze-core samples,
which average from 3 kg to 20 kg per sample can then be analyzed
by use of dry sieve analysis.
The sampler is supplied with the three tube probes, hoses,
valves, regulator, and tank (20 lbs.) of CO2 (carbon dioxide).
406-015 Freeze Core
Sampler 36 lbs.
