Application And Observation Of Sediment-water Interface With Optical Planar Sensor

The Sediment-water interface(SWI) is an active place for chemicalmatter exchange and biogeochemistry circle. Therefore, the measurementof concentration and distribution of dissolved at SWI is very importantto understand the complexity of the role of biogeochemical cycling.Microelectrode probe for dissolved oxygen and pH measurement are limitedin one directional measurement, Since the1970s’, the new developedplanar optodes shown its ability to record spatial dynamic changingprocess of Sediment-water interface in two dimensions and, provided aneffective technological method for the revelation of natural sciencequestion.The membrane based on platinum octaethylporphyrin and coumarin hasbeen prepared to construct a ratio method planar optode systems. Asimulated experiment has been carried out to observe the variation ofdissolved oxygen consumption in the sediment-seawater interface duringjellyfish decomposition. The experimental results proved that thefeasibility of monitoring the dynamic changes of dissolved oxygen in themicro structure of sediment-water interface. In the first day, theconsumption rate of dissolved oxygen in the sediment water interface is0.2mg/L H-1, the second day, the rate is0.04mg/L H-1.In the first day, theconsumption rate of dissolved oxygen at the bottom of the water space is0.28mg/L H-1, the second day, the rate is0.14mg/L H-1,the third day，the rate is0.13mg/L H-1， experiments prove that the decomposition of jellyfish at the sediment water interface formed severe hypoxia zone inseawater around the sediment-water interface in3-4days, thedecomposition of jellyfish changed the distribution system in seabedarea, it will have a greater impact on the marine environment.Currently used fluorescent pH indicator suffer the drawback ofleakage of fluorescent indicator because of its hydrophilicity. Inthis study, a sensing film consists of1-hydroxy-3,6,8-pyrenetrisulfonicacid trisodium salt(HPTS), tetraoctlammonium cation(TOA) has been usedto construct a pH observing systems. The novelty of our sensor systemis that by using of an excitation light source and two emission spectrumwith a3CCD cameras.The system simplifies the tedious step oftraditional dual excitation and dual emission light, building thefoundation for the construction of practical in-situ observation system.