184-10 A Modified Lightweight, Inexpensive, Percussion Coring System for Shallow (< ~4 m-depth) Ice-Covered Lakes

Session: Lakes of the World Through Space and Time: Archives of Climate, Paleoenvironments, Ecosystems, Geohazards, and Economic Resources (Posters)

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Abstract:

Recovery of lake-bottom sediment is fundamental to paleolimnogeologic studies, with investigations of remote lakes necessitating lightweight and easily transportable coring equipment.  Traditional percussion coring systems conducted from a stable ice-pack surface from which a weighted driver is repeatedly lifted and dropped below the ice surface (e.g., Reasoner, 1993; J. Paleolimnol. 8, 273-281) require relatively deep (≥ ~4 m) lakes.  Modifications to this original coring system are presented for relatively shallow (< ~4 m-depth) ice-covered lakes.  Initially a clear tube is inserted into the 7.62 cm-diameter PVC sewer pipe core barrel, which compensates for the thickness of the core-catcher/cutting-edge assembly, strengthens the core barrel, allows for visual inspection of recovered core, and in which holes may be drilled for porewater extraction.  The one-way valve assembly at the top of the core barrel has been modified to be compressed against the clear tube.  To drive the core barrels into the sediment from above the ice surface, the core-head is capped, on top of which is mounted a 3/4-inch galvanized floor flange secured with U-bolts.  The interior of the core-head cap is strengthened with fiberglass-reinforced epoxy.  Ratchet straps may be connected to the U-bolts, and to the ice surface with ice screws, for pulling or ratcheting the core barrels into the sediment.  The floor flange allows for connection of galvanized pipe that serves as a drive-head for hammering with a mallet.  The original weighted driver used below the ice surface is capable of asserting ~80 N of force to drive the core barrels into the lake-bottom sediment.  However, pulling down on the straps, ratcheting the straps, and pounding with a 1.8 kg mallet, assert ~900 N, >>5000 N, and ~1200 N of force, respectively.  To reinforce the top of the core barrel, the bell of the sewer pipe should be cut off just above the flange and glued at the top of the core barrel against the remnant flange.  Before inserting the core barrels into the lake, a flexible coupling is secured low on the core barrel using stainless steel hose clamps.  An icicle hitch is tied around the coupling using a coarse-weave polyester rope.  Climbing rope is attached to the icicle hitch for retrieval of the core following the originally proposed pulley system anchored by ice screws on the ice surface.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

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