Martti Korpijaakko

Uusi kairatyyppi tilavuustarkkojen turvenäytteiden ottamiseen

Korpijaakko M. Uusi kairatyyppi tilavuustarkkojen turvenäytteiden ottamiseen.

Tiivistelmä

Dry density of peat — the quantity of dry matter of peat held in unit of volume of peat in situ — depends on several factors, the most important of which are peat type, degree of humification (comp. e.g. Päivänen 1969, Korpijaakko and Rad-forth 1972) and water content (Korpijaakko 1975). Thus knowing of peat types and their degree of humification is not enough for accurate evaluation of the amount of dry matter contained in a peat deposit. Undisturbed samples of known volume from different depths and sites are needed. A piston sampler for this purpose has been developped and applied in the Geological Survey of Finland. The sampler is a modified version of the stationary piston sampler used mainly for palynologieal studies in the Geological Survey. When the coring is performed the piston-cone component of the sampler is kept stationary while the sharpened cylinder is pushed down. Thus the vacume caused by the piston helds peat core on its place while the cylinder cuts it off from the surrounding matter. Because of the strong vacuum effect good samples are obtained also from wett deposit. The diameter of the new sampler is 10 cm (Fig. 1). The cylinder component is devided into three parts. The one in the center is the sample cylinder proper. Its length is 20 cm. The lowest part is 10 cm long. The peat held in this part prevents water from running out from the sample cylinder while the sampler is hoistened. The length of the topmost part of the cylinder is 20 cm. Its function is to hold at the end of the sampling procedure the piston- cone component plus the peat which was disturped while the sampler was pushed down. The cylinder parts are jointed with nuts, which are rotated on to the upper part when the sample is removed. Cylinders are made off stainless steel. Transparent plastic cylinders have been used, too. They are good only in the peat deposits with no sunken logs. The sample cylinder is driven into peat with a rammer. The sampler is hoisted with tongs, which are also used to keep piston-cone component stationary while taking a sample. The equipment is portable. 3—4 men are needed in sampling.

Vastaanotettu 31.10.2017 Julkaistu 1.1.1981

Katselukerrat 1162

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