DMS sensor

In the Ocean when Phytoplankton (small/invisible Algae) die, they release a compound that is almost immediately used as a carbon and sulfur source by even the smallest organisms -Bacteria- to grow.

During this process of degradation is produced a gas called DMS (Dymetylsulfide). This gas is released to the atmosphere, that helps in the formation of clouds, making our planet cooler, counteracting the increase of temperature due to climate change.

DMS and other volatile sulfur organic compounds, that are released during the degradation of phytoplankton by the surrounding bacteria gives the sea smell that we all experience to sniff when approaching a beach area.

Because DMS is a byproduct of phytoplankton plus bacteria degradation, we can measure it in the environments to indicate phytoplankton biomass/decay.

 

Last spring we had the opportunity to test a novel DMS sensor developed by NASA-Ames. The aim was to validate its use to measure DMS concentrations in the air as a proxy of phytoplankton biomass gradients across ocean fronts. In order to do so, the sensor was installed onboard of one of our UAVs.

The sensor needs to be exposed to the air but at the same time sheltered from the elements, so LSTS and FlightWave designed a nose cone for our drones with this purpose.

The air inlet and outlets guarantee the sensor has an air flow going through it. The datalogger reads the data collected by the sensor and sends it to the drone's main CPU, which will then report the results in real time back to the basestation (usually a ship in this scenario).

But why use a drone?

We want to find out more about DMS and its relation to the fronts we are tracking. We want to discover where it is and how high above the water we can detect it. With an aerial drone we can fly at different heights and also explore the area around our ship as it cruises, once it can cover a large area quite quickly. In a nutshell, using a drone instead of installing the sensor directly in the ship, for instance, allows us to extend its range.

What we learned so far is that the sensor is capable of detecting the presence of DMS from the air, but after being exposed it takes too much time to stabilize again for an UAV application. We also learned that the sensor is affected by the environment, so the datalogger would benefit of having a temperature and humidity probes in the air flow to which the sensor is exposed. We are currently working with this information to improve the sensor and the datalogger.

Collaborators: LSTS (datalogger), CIIMAR (DMS calibration tests), FlightWave (nose cone) and NASA-Ames (sensor prototype).

References: Exploring Fronts with Multiple Robots - SOI Cruise