ABSTRACT:

During AT11–7 Alvin/Atlantis cruise in America, newly developed chemical sensor and self-contained multi-channel data logging instruments which were designed by Zhejiang University, China were tested at the depth of 2500m to quantify variations of time series in hydrothermal vent fluid chemistry. The units were placed at different vent sites taking data at a rate of 5 second per-scan and recording up to 12 days. This experiment is the first time to detect the hydrothermal vent for 12 days in the world. The key technique is that the data logger must have low power consumption and large storage for uninterruptedly detecting for a long time just used by 3 normal batteries. Some strict requirements must be satisfied for any sensor data logging system deployed in this extreme conditions: more than one chemical species along with temperature should be simultaneously measured and recorded, the acquired signals need to be amplified, regulated, and stored in the memory inside the pressure chamber of small size and low power consumption. The multi-channel sensor data logger mainly consists of two parts: the sensor housing (40 cm × 5 cm diameter) and the circuit housing (38 cm × 8 cm diameter), which can be easily connected to the sensors through a underwater connector and cable.

INTRODUCTION

Hydrothermal activities can be found in global seabed with different geological background. Thermophiles are found at the hydrothermal vents, together with eubacterium and the branch of eukaryote, can be traced to the early stage of life origin on earth and it is also recognized that the environment at the hydrothermal is similar to the environment where life originated in the globe about 3.8 billion years ago and life is likely to emerge in this special kind of environment, which is one of the recent hotspots of study on life's origin.

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