OCEANSensor

OceanSensor is a 3-year EU-Martera project that started on June 1, 2018 and ended on December 15, 2021. The main goal was to develop, improve and refine the use of existing underwater sensor technology. There were six partners from four countries in the project. The project was co-ordinated by Prof. Eric Achterberg at the research institute GEOMAR in Kiel, Germany. Aanderaa Data Instruments (Bergen, Norway) was involved in four different technology development tasks of which two has led to major product developments that was/will be commercialised. 1. Development of a miniaturized in-situ calibration system for oxygen, pH and pCO2 (GEOMAR & Aanderaa): By calibrating automatically, in the field, the accuracy of long-term, years, measurements will be improved so that decadal changes in the deep oceans can be detected with more certainty. Challenges are the mechanical reliability of the system and long-term stability of the reference material. We developed two types of systems one that used calibration liquids and another one based on calibration gels. Prototypes were designed and built in 2018-2019 and were successfully lab tested in 2019-2020. In parallel long-term liquid/gel stability was evaluated. Unfortunately, because of a work-shop lock down at Geomar, due to Covid-19, the designed field prototype for liquid calibrations was not finalised in time. We did however successfully test the gel calibration method in the sea and concluded that an automated gel system should be easier to manufacture than the liquid based. 2. Improvement of oxygen optode technology to measure at low oxygen and under high pressure (Aanderaa): Aanderaa revolutionised oxygen measurements in natural waters by introducing optical oxygen sensors in 2002. In the OceanSensor project we have developed and tested new optode prototypes. The new sensors were a factor of 2-3 better in long-term stability, to handle high pressure and to measure low oxygen concentrations (nM). The new technology will mean a step change in oxygen measurements and will be commercialised in Q2 of 2022. 3. Use off-the-shelf instruments and sensors to measure small chemical gradients close to the sea-floor (Aanderaa & GEOMAR). This could be a future method asses biological, chemical and geological sea-floor activities, such as gas release from seismic activities, which could be an early warning for an earthquake. Major technical challenges include sensor stability, accuracy and resolution and a robust method to calculate the mixing/turbulence close to the bottom. We lab evaluated and field-tested new methods to measure turbulence with existing ultrasensitive pressure sensors. The method seems to work well but needs further work and development. Simultaneously we improved and tested new algorithms in the pressure sensors to detect cm waves from down to 40 m water depth. The method worked well and was commercialized in Q1 of 2021. During field work in August 2020, we collected 10 days of high-quality oxygen gradient data that will need to be combined with the pressure-based turbulence measurements to calculate exchange rates, fluxes, between the seafloor and the overlying water. 4. Automatic glass incubators to measure algae and bacterial activity in water (Aanderaa): We developed and did preliminary test of glass incubators that are made to be fitted to Aanderaa oxygen optodes and operated by our multiparameter instruments. The idea is to pump in water and measure the oxygen consumption (mainly by bacteria) or oxygen production (mainly by algae close to the surface). More evaluations will be necessary to check that this method is accurate and reliable at different activity levels. The OceanSensor project has enabled the development and field testing of new sensor technology. Several of our existing sensors were improved with enhanced measuring possibilities which should lead to a rapid commercialisation.

We successfully accomplished all planned and several additional tasks. The working principles of an in-situ calibration system was tested for Trace-O2, pH and pCO2. Long-term tests of ultra-stable O2 foils were complemented by pressure tests and in a low oxygen detection workshop. We found that nanomolar detection is possible with the new Optodes. Existing wave/tide/pressure sensors were updated with new software to detect small waves and field proven. We made eight field campaigns. Turbulence and gradients of O2 were measured during a 10-day deployment and a new type of compact glass incubation chamber to measure water respiration was tested. The project has resulted in commercialisation of a better Wave-Tide sensor, in 2021, and in the launch of the new generation Oxygen Optodes, in 2022. This is likely to have significant impact on the success of Aanderaa and will make a major contribution to science on the possibilities to accurately measure Oxygen in the Oceans.

OCEANSensor is a 3-year research and development project with the main goal to develop, improve and refine the use of underwater sensor technology. The project is part of the Martera program and starts on June 1, 2018. There are six partners from four countries in the project. Three partners are research institutes: GEOMAR (DE) coordinator, National Oceanography Center (UK) and LEGOS (FR). Three partners are companies: Trios (DE), NKE (FR) and Aanderaa (NO). The main focus of the Norweigan partner Aanderaa is: 1. Together with GEOMAR make a step change in the measurement metrology of pH, pCO2 and oxygen through the development of a miniaturised in-situ reference solution delivery system. 2. Develop a mechanical in situ cross-referencing method for sensors to measure high resolution gradients close to sea-floor. If working well such a system could serve both to quantify metabolic rates of sediments (e.g. consumption of oxygen, release of nutrients) and as an early warning system for earthquakes and leakage from e.g. Carbon Capture and Storage (CCS) sites. In conjunction with this new methods to estimate the transport coefficient at the seafloor will be tested. The intention is to use, as much as it is possible, our existing off-the-shelf instruments and sensors that are compact, deep-sea (6000 m) rated and consumes minimal amounts of energy so that year long autonomous deployments are feasible. For evaluation of the developed technology in the field there will be Argo floats (NKE), surface roaming vehicles (Sailbuoy), an easily accessible cabled observatory (in the Koljoefjord) and two autonomous bottom landers available in the project.