Amphibious Trilogies

Moving gas #2

Interview with Amanda Steggell and Anja Hajdukovic, a master student studying Environmental Sciences, Climate change impacts, Governance and water Sciences at the University of Geneva.

The interview took place on the Kola Meridian transect, Barents Sea, 23 June 2019, Day 3 of The Arctic Floating University Expedition.

Setting the scene

With help from supervisor Dan McGinnis, Anja shares the project Flux CO2 and CH4 with Adrien Simon. They are studying the transport of gases in the water column, especially CO2 and methane (CH4). The aim is to follow the path and the fate of these gases by taking and analysing water samples along the Kola Meridian transect.

Anja and Adrien collaborate with a related project, CO2 – CH4 relationship, in which Amélie Gelbmann and Alexandrine Massot will analyse the relationship between CH4 and CO2 fluxes in surface waters. The aim is to make a profile of the two gases and to identify hot spots of gaseous emissions and gas exchange zones. Both projects relate to the ongoing theme of global warming.

All four are on the uppermost level laboratory of Prof. Molchanov. They have brought fresh samples of water collected on the sample station1. on the lower deck. In essence, this interview was more like a physical demonstration with running commentary.

Amanda Jane Steggell (AJS): Can you elaborate on the process of extracting methane from water samples.

Anja Hajdukovic (AH): So here, we take water into a Niskin bottle2., and for each 12 bottles there’s a specific depth and a specific temperature, and we go from the surface (water) to the bottom layers. And here, we see 105 ml water samples. We do this to take in air from the atmosphere. So now, we have a space for the water and a headspace for the air. And what we are doing now is two minutes of shaking (the bottles) in order to mix the water and the air, to have a homogeneous gas concentration. So now, we’ll have to wait for two minutes. – As my teacher Dan McGinnis, a specialist in the field, he says there’s no machine that can directly measure the methane in the water. This is why we collect and transfer the gas to an exetainer3.. I’ll show you later. We will analyse the samples in Switzerland.

Adrien Simon (AS) joins the running commentary.

AS: Sometimes we can see dolphins from the window.

AH: Yeah, hopefully we’ll see the dolphins, and the light is really nice too. Though we are not doing this, you can see here, a machine that is measuring C02 in the atmosphere. You can see the results written in green on the computer screen. What you are seeing is the concentration of the sour-tuned atmosphere.

AS plays a romantic ballad on his phone. Two minutes of rigorous shaking has passed.

AN: Now we explain, step by step, what we are doing. So now, we will use a transference syringe. I will connect it to my sample, and it will transfer the gas to the syringe. It’s important that the syringe is really dry because my aim is to only have gases. If I have water, it will affect my end results. The last step is to transfer the gas from the syringe into a exetainer. I will put it in the middle. I’m supposed to press, and yes, it works. Of course you cannot see it, but there’s gas inside.

AJS: So you have all these samples, what’s different about them?

AS: The difference is in the sampling station.

AJS: So, bottles marked with yellow tape might indicate that the water samples have come from the bottom layer of the sea.

AS: No. You have to look at the numbers. Bottle 9, for example, corresponds to the Niskin bottle. number 9. I’m not sure, but I think this one is 100m in depth. In the sampling station we let the Niskin bottles sink, and each bottle will close on a specific depth.

AN: Each time, there’s someone that writes down the depth. I see that bottle number 1 is at 10m, 2 is 20m, and the last one, bottle 12, is at a depth of 280m.

AJS: That’s quite deep.

AN: Yes, it’s quite deep. Apparently, the Arctic has shallow waters when compared to other oceans. – So now we have the basic information; wind speed, air pressure and even about waves. Alex is writing down all the specific details of the samples that are required for us to complete the course.

AJS: So now, all the methane samples are packed and parcelled, ready to take back home. I thank you for your efforts.

1.Sampling station refers to the circular frame of CTD probes, a package of electronic instruments that measures the properties of conductivity, temperature, and depth.

2.A Niskin bottle is a plastic cylinder with stoppers at each end in order to seal the bottle completely. This device is used to take water samples at a desired depth without the danger of mixing with water from other depths.
– Source: http://www.vliz.be/en/Niskinbottle

3.Exetainers are commonly used as measurement vials for the determination of methane (CH4) and nitrous oxide (N2O) concentrations in liquid and gaseous samples from aquatic environments.
– Source: https://aslopubs.onlinelibrary.wiley.com

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