Section outline

    • A columnar sampler is a generic term for an instrument that collects sediment samples by piercing a cylindrical cylinder into the seafloor. Since this type of instrument can collect samples without disturbing the stratigraphy of the sedimentary layers, the collected samples are analyzed and classified according to their ages. Typical columnar samplers include piston corers, multiple corers, G.S.type core sampler（ASYURA）, Freger core sampler, and HR type core sampler.

    • ・Piston Corer

       The piston corer is a gravity free-fall type sediment sampler. A metal cylinder connected under the main weight is thrust into the seafloor to collect sediments in a cylindrical shape from several meters to a maximum of 20 meters below the seafloor. It is the deepest mud sampler of its type, and the collected samples can be used to estimate the earth's environment hundreds to hundreds of thousands of years ago.

       The observation workflow for the piston corer is as follows. First, the main body of the piston corer is connected to the trigger of the balance type and lowered to the seafloor using a winch. When the pilot weight contacts the seafloor, the trigger operates and the corer drops freely, penetrating the seafloor by its own weight and momentum. The characteristic of the piston corer is that negative pressure is generated by the piston rising inside the cylinder during penetration, allowing the sampler to penetrate smoothly and deeply. This negative pressure also prevents the loss of samples from the bottom of the pipe (Figure 2).

      　On the other hand, since the sediment surface samples are disturbed when the sampler is thrust into the seafloor, a small corer is used for pilot weights and the sediment surface is sampled separately.

      ピストンコアラー

      　　　　　　　　　　　　　　　　　Fig 2 Piston Corer and Piston Corer Schematic

      天秤式トリガ　trigger arm

      メインウェイト　main weight

      採泥管　corer tube

      メインワイヤ　main wire

      ピストン　piston

      パイロットワイヤ　Trigger wire

      パイロットウェイト　Trigger weight, release weight

      　

      Link to detailed course→「ピストンコアラー」

    • ・Multiple corer
       As shown in Figure 3, the multiple corer consists of a wreck constructed of metal pipes, a weight that moves up and down inside the wreck, and a polycarbonate cylinder attached to the weight. When the mast reaches the seafloor, the weight descends and the tube quietly penetrates into the sediment, collecting sediment up to about 30 cm above the seafloor surface, together with water directly above the seafloor. It is called a multiple corer because multiple tubes can be attached.

      　Samples collected with this sampler are brought on board directly from the seafloor environment because the sediments are not agitated in the cylinder. Therefore, it is widely used to study the interaction between the water directly above the seafloor and sediments through mass exchange, and the dynamics of microorganisms that specifically inhabit the surface layer of sediments.


      マルチプルコアラー

      　　　　　　　　　　　　　　Fig 3 Multiple corer

      　Link to detailed course→「マルチプルコアラー」


    • ・G.S.type core sampler（ASYURA）

      　This is a small columnar sampler with three polycarbonate tubes attached to a weight. Although it does not have a harp like a multiple corer, it can collect the same samples as a multiple corer if it is allowed to penetrate slowly into the seafloor. The top and bottom lids close when pulling out from the seafloor to prevent sediment samples from falling, the same mechanism as the multiple corer.　
      　By attaching this sampler as a pilot weight for piston corer observations, the sediment surface layer, which is disturbed by the piston corer, can be sampled simultaneously in a series of observation operations.


      　　　    

      　

       　　　　　

      　　　　　　　Fig 4　G.S.type core sampler（ASYURA）

      ※ Picture provided by : Hokkaido Research Organization（HRO）


    • ・Freger core sampler

      　The Freger core sampler is a gravity free-fall columnar sampler shaped like a rocket with a weight on top of a metal cylinder. The weight and the force of the free-fall through the sea allow it to penetrate the seafloor and collect sediments in a few dozen centimeters of the seafloor surface layer. A polyvinyl chloride or acrylic tube (inner tube) is inserted into the cylinder, and the collected sediment is held inside the tube. The lower part of the tube is equipped with a metal check valve, and the upper part of the tube is equipped with a lid that closes when the mud sampler is lifted out of the water, preventing the collected sediment from falling out.

      　Since this sampler is relatively small and can be carried by human power, observation work can be done by hand without the need for winches, cranes, or other equipment. Therefore, they are mainly suited for surveys in inner bays and coastal areas such as Tokyo Bay and the Seto Inland Sea. It can also be used as a pilot corer for a piston corer as well as an ashlar corer.


      　　Fig 5 Freger core sampler

      　 Picture provided by：RIGO Ltd.

      　


    • ・HR type core sampler

      　The HR type core sampler is a sampler with a metal bit attached to the end of an acrylic tube connected to a weight. Upon arrival at the seafloor, a trigger on the top of the weight activates the bit, which slowly penetrates the seafloor under its own weight. When the wire or rope is pulled up, the bit rotates 90 degrees to form a lid that prevents the sample from falling out. Because of this mechanism, the device is most commonly used in inner bays and lakes where sediments are soft. The weight of the main body of the device is only enough to be lifted by human power, making it suitable for surveys conducted by small vessels.


      　　Fig 6 HR type core sampler

      　Picture provided by：RIGO Ltd.