ABSTRACT:

In hydrothermal vent's plume areas, the seafloor sediment contains high concentrated barophilic microbes and gases. Sealing the sediment core at in-situ pressure is essential for sampling. A pressure tight coring technique, which could be introduced in the modification of traditional multiple corer, is put forward. The three basic parts, sample transfer technique, seal self-tightening technique and semi-active pressure holding technique were discussed. Based on these, the pressure tight multiple corer was developed and successfully researched through experiments. The results show that the corer has a good ability in sampling and in-situ pressure holding.

INTRODUCTION

Deep-sea sediment sampling technique is essential for the investigation of deep-sea environment and resource. Many effective sediment sampling ways have been adopted in the past few years and many sampling equipments have been developed successfully for various sampling activities. For instance, multiple corer and piston corer can collect sediment and the seawater around it on the seafloor with the help of gravity. Another deep-sea towing-style sampler can pick suspended particle by the use of trawl and television-assisted clamshell excavator can gather superficial deposit and mineral on the seafloor at the aid of deep-sea camera technique (Yan, et al., 2001). However, such sampling technique has its own disadvantage that the in-situ pressure of the sample cannot be maintained for a long time after it is taken from deep sea. The sediment collected from the deep sea will change its character as the pressure and illumination varies (Tsuji, et al., 1993), such as the dissipation of the gas phase dissolved in the sediment, the change of ionic oxidation state, the decomposition of the organic element and the vast scale death of the barophilic microbes. These changes make it difficult to know the primitive component and the original state of the sediment (Rack, 2001).

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