Technique to obtain ready and finer scale interval in-situ underwater sediment sub-sections
In the field of oceanography, finer scale sediment sub-sections are pre-requisite at different stages of geological (sedimentological, geotechnical, geochemical, geochronology, micro-paleontological, gas hydrate, etc.) biological (macro-, micro- and meio benthos, microbiology, etc.) and chemical research (pore water, etc.). In the existing methods, the sub-sectioning (sub-sampling) of long (>6m) deep-sea sediment cores is performed after retrieval of the core on board. Also, the sub-sectioning method is tedious and time consuming, which requires large space, large manpower team comprising of 6 to 7 persons. Besides this, the method is not eco-friendly, and provides sediment sub-sections of approximate size intervals with doubts of contamination.
To overcome all these difficulties, a portable special core liner (SPCL) was designed and tested successfully on board NIO’s coastal research vessel CRV Sagar Sukti to obtain long sediment core with ready finer scale (in-situ) sub-sections. The fine sub-sections of the sediment can be easily and quickly removed from the SPVL and brought in use. The SPCL is light weight, and portable which can be operated easily with gravity or piston corer assembly. The SPCL can be reused for unlimited times. It requires a small (table top) area and maximum 2 persons to handle collection/ removal of sub-samples.
The complete specification for NIO Patent Proposal IPMD Ref. No. 0270NF2006 has been filed at the GOI Patent Office on 03-05-2007, vide Application No. 0960DEL2007.
Following figures shows stages of preparation of portable and reusable SPCL (Fig. 1 and 2), operation of SPCL on board CRV Sagar Sukti using gravity corer (Fig. 3 and 4), and easy removing of finer scale sediment sub-sections from SPCL in laboratory by 2 persons (Fig. 5 and 6).
A simple device to obtain precise finer scale sediment sub-sections from box or spade corer
The seafloor sediments obtained by the box (50x50x50 cm) or spade (20x30x40 cm) corer are required to be sub-sampled immediately after its retrieval on board. For sub-sampling purpose, the sub-cores are obtained in acrylic or PVC liners of different diameters by inserting them in the box (Fig. 1). The sediments in the sub-cores are sectioned at required intervals following push core or other method. Most these methods are usually tedious, strenuous, time consuming, and lack precision. The proposed sediment sub-sectioning device (Fig. 2) overcomes all above difficulties. The device has been successfully tested in 2009 for number of times on board Russian research vessel R/V A. Boris Petrov (ABP-38) cruise in the Central Indian Basin (CIB). The device is low cost, user friendly, small, light weight, portable, slender and occupies 0.25 m2 floor area. It can be extensively used (without wear and tear) to obtain precise sub-sections of sub-core sediments with an ease. With this device, the possible sub-section interval van be as small as <1 cm, and/or any combination between 1 to 10 cm (or more).
This is Patent Application No. 0068NF2010, filed in India on 11-11- 2010.