The Design Of A Planar Optode For Benthic Dissolved CO₂Measurement

Transportation of between sediment-water inferface is an importantresearch area about marine geology science. In this study a dissolvedcarbon dioxide sensor is made by using the fluorescent dye, HPTS（1-hydroxypyrene-3,6,8-trsulfonate, HPTS） incorporated into a polymermatrix,polyHEMA-co-EGDA. The HPTS-incorporated polymer membrane soakingin sodium bicarbonate buffer solution for24hours. It is shown that theresponse time is about2-3mins, and it have preferably repeatability andprecision. The planar optode have little sensitivity about change oftemperature. In laboratory environment,a seep CO2experiment is conducted.The results show that the disclosure of the buried CO2can rapidly changethe pH value of sediment-water interface,and it will reach the rebalancein few days.In this paper, the first part that summarizes current technology ofsitu sensors for dissolved CO2measurement in the sea. It is aimed atdefects of mainly survey that is situ two-dimensional measurement fordissolved CO2,this paper researchs a optode of dCO2.This method usedphysical entrapment to immobilize fluorescent pH indicator dye8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt (HPTS) within anethyl cellulose membrane, and coated with a gas permeable siliconemembrane.The ingredient of ethyl cellulose membrane is polyHEMA-co-EGDA.The test experiment about performances of dCO2membrane shown thatthe planar optode and dCO2have perfect relativity:the response time isabout2-3mins;the membrane has good repeatability and precision; it hasgood stability at temperature range0°-30°C. Using this planar optodeand industrial digital camera build a complete observation system. The system proving the feasibility of planar optode in dCO2dynamic changeprocess observation though simulation experiment.