Wednesday, September 18, 2013

Kasten Coring!

            On Tuesday, September 17 the science party on the R/V Revelle deployed and recovered a somewhat "old school" core, the Kasten Core. The Kasten core sacrifices length for volume; compared to the typical PVC core liners, with a 4 inch diameter and up to ~12 meters in length, the Kasten core liner boasts a 12 by 12 inch surface area but a maximum recovery of just 3 m. As a consequence you obtain more mud per depth interval, allowing a very detailed picture of the recent past. In regions of high sedimentation rates, high-resolution records of the Holocene (past 10,000 years) may be obtained.
            In the early morning hours, the "A-Team" launched the first and only Kasten Core of the cruise off the northern coast of Papua New Guinea (03° 14.538' S, 143° 04.577' E). Though the cast was successful, returning 2.24 m of sediment from 900 m water depth, a number of complications arose. First, when full of mud (and even without mud) Kasten cores, like piston cores, are extremely heavy and must be mechanically turned sideways before bringing them on deck. Further, Kasten cores allow the sediment to shift when the core is turned sideways. Thankfully, the OSU coring staff came prepared with "liquid foam". We performed a bit of shipside chemistry,mixing a two part resin into an empty (knockoff) Pringles can to mix for 50 seconds before dropping the concoction, Pringles can and all, into the top of the core. We expect to find a diagnostic "Pringles layer" within the core as evidence of this event. After a suspenseful 10 minutes the foam appeared to have set and we proceeded to bring the core inboard.

Empty Kasten corer just prior to being launched.
Still, our work was not yet done. We needed to determine how to archive and move ~ 1000 (+/- a bajillion) pounds of mud into the refrigerated van (aka reefer van). The main section of the core is easily archived in the steel liner within the Kasten Core itself, needing only a lid and two plastic end caps screwed in. However, ~1 ft of mud was trapped within the core cutter, a steel piece at the base of the core that is sharpened slightly at its base to cut easily into the sediment. After some awkward lifting and shaking the majority of the cutter mud was removed intact and placed above the foam at the top of the liner, providing a perfect fit (see picture below). Packed safely within its liner we were ready to move it out of the hot sun and into the refrigerated van.

The Kasten Core in its liner.
Yet once again we were faced with moving ~ 1000 pounds of mud and, at the end of a long shift, the prospect was a little disheartening. With the help of our friendly neighborhood Restech, Keith, we managed to wrestle the core onto a cart, and in a moment of much needed comic relief, we maneuvered the core with Keith sitting on its top across the deck to the reefer van (with Keith giggling happily the whole way). At the van, the cool, though the somewhat creepy, musty, and chemical like air pooled out of van and refueled our strength. One last struggle ensued as we strained moving the core up and into van. Mission accomplished!