Papyrus: a methane emitter and natural wind vane

The papyrus swamp measurements team
Tue 22 January 2019
Part 1

Having planned out the next few days flights – to lakes/wetlands as well as fires – and with no point refining the plans based on the weather forecast because we don’t know exactly when we will be able to start flying, I’ve joined Rebecca again to do some air sampling. This time with intent, and with a full rucksack containing anything I might need (unlike yesterday).

We are currently in a taxi out to see a contact, Steve Forsyth, who works at Mission Aviation Fellowship – Uganda, and is based at an airfield by a papyrus swamp. MAF is an organisation that operates small aircraft to transport refugees from nearby countries like the Democratic Republic of Congo or Sudan. The swamp will be a source of methane and so will be a good opportunity to work out the carbon-13 fingerprint of such an ecosystem. The principal investigator of this project, Euan Nisbet, has sampled here before, so it will be good to find out whether the fraction of carbon-13 varies over time or is very consistent.

Getting out of the conference room is a good chance to stop obsessing over ever evolving weather forecasts and see some of Uganda. And I can make myself useful by taking photos of the sampling location at very least.

Part 2

We are on the way back from the airfield now. It was completely surrounded by papyrus swamp, which meant we could access it quite easily. We were escorted around the airfield by Ivan, who was essential in helping us not get our feet wet (we were not keen to lose a trainer in the swamp!) while getting as close to the swamp as possible.

The papyrus plants were extremely tall in places – close to 4m probably. Some areas were cut down to the stem, and they grow back in about a month according to Ivan. The stems themselves are very strong, and are excellent wind vanes of you ever are in need of one. Which I did, as I was taking wind measurements to accompany the air samples.

In all, we took 13 samples from locations close to the surface of the water up to about 2m high, all around the edge of the swamp, plus one background sample further away from it. This will allow us to find out the carbon-13 fingerprint of this papyrus swamp, where there were the highest methane concentrations. For example, the papyrus that was cut down to ground level may emit more or less methane than the fully grown area and maybe the measurements will give us an indication of that.

 

Serendipitous sampling

Monday 21 January 2019
Termite mound

Taking an air sample beside a termite mound (Steve Andrews, Rebecca Fisher and our very understanding tour guide)

Today was another down day, with access to the aircraft for instrument scientists. We are fairly well prepared for the flights, as we originally wanted to start flying today, but hold-ups with permissions mean that we will be lucky to fly tomorrow. So we have got several flight plans fully prepared, and we are just keeping an eye on the weather forecasts and waiting for the all clear.

Instead of obsessing over the weather, some of us went to buy local SIM cards and have lunch. So far, so uneventful. We then decided to walk back to the hotel via the botanical gardens, and this is where the day turned up some unexpected excitement. Rebecca Fisher from Royal Holloway, a seasoned and clearly very dedicated field scientist, had come prepared with three air sampling bags and a pump. So when we saw termite mounds in the botanical gardens, Rebecca and I were grinning with glee, as termites are one of the more unusual sources of methane, and one which we hadn’t measured before! The down side of our enthusiasm was that the termites weren’t terribly pleased and one bit me. I admit that termites weren’t on the risk assessment as we had no idea we would see any.

After learning some more about indigenous and non-indigenous plants in the gardens, and spotting various birds (kingfisher, ibis, cormorant, egret and a few more unidentified ones) and a troop of monkeys, we found some cows hanging out with some egrets. And of course, took another sample, cows being a favourite methane source to measure.

Cows and egrets in the Botanical Garden, Entebbe

Cows and egrets in the Botanical Garden, Entebbe

One final sample on the beachfront later, and we were done with the sampling. Rebecca will analyse the air back in the UK to see how much carbon-12 and carbon-13 there is in the methane. Sampling close to a source (e.g. a termite mound) is a way to identify that source’s signature amount of carbon-13 relative to carbon-12. The better we know this from a range of different sources, the better we can work out the origin of a methane measurement far away from the source, by matching up this so-called isotopic fingerprint.

For more about this kind of isotopic fingerprinting, see this blog from our previous campaign about methane in the Arctic.

sampling a cow

A cow shows Shona Wilde and Rebecca Fisher what she thinks of their air sampling!

There is no science without coffee

Ethiopian Coffee

Without coffee, there is no science

I write this at 8am on a Sunday in a bustling airport in Addis Ababa, with a few hours to spare before my connecting flight. I had intended to prepare a background post outlining the plan for the field work and the wider project, but doing  anything non-essential in the run-up to the trip proved a little over-ambitious.

A colleague and I are flying out to Entebbe, which is on Lake Victoria in Uganda, about 30km away from Kampala, to join the rest of the detachment team to work on the FAAM research aircraft. We took a red-eye flight from London and as a result I really needed the excellent Ethiopian coffee I just finished. We were supposed to start the research flights tomorrow, but the final sign off has not yet been obtained from the local officials – not for want of trying! So instead, today is a “hard down day”, meaning no access to the research aircraft at all, because without the sign off, we can’t get airborne.

So Monday will be used to get all the instruments up and ready while the aircraft remains on the ground and hopefully Tuesday we will get airborne. We really have a packed schedule, as we are only doing MOYA flights Tuesday to Friday and then one more on Tuesday next week (another project called HyVic is flying over Lake Victoria on the intervening days). The shorter detachment saves on costs, but means we are at the mercy of the weather. To make sure we can fly every day we have several different flight options to choose from: Lake Victoria, Lake Kyoga, Lake Wamala and wildfires in northern Uganda. We will pick one of these based on which location has the best weather conditions, and fingers crossed we have time to do 2 of each. We also hope to circuit Kampala to sample the city’s emissions as part of one of the flights.

Why are we going to all this effort? Mainly to figure out how much methane is coming out from the lakes, wetlands and wildfires. This will help us to piece together the global methane trends – a key factor in how much the planet will warm in the coming years. To do this, we sample the methane in the atmosphere while airborne, as well as ethane and other pollutants. Some of these measurements come in real time, others are taken back to the UK to analyse for carbon isotopes, which gives us a clue as to the emissions source. You will find blogs from our 2017 airborne field work, based in Senegal, where wildfires were sampled. I have to say, based on the turbulence we felt on the commercial flight here, I am not too keen on flying near wildfires (which cause turbulence from their heat) or storms (which are quite common even though this is the dry season for Uganda).

I think the boost from the coffee is wearing off now, so I will sign off from my first post. There will be more content over the coming week, when I hope to have more than a few hours doze before sitting down to write.

Methane session Open for Abstracts – AGU Washington

The MOYA projects PI Euan Nisbet will be convening a session on methane in the AGU Fall Meeting. This years AGU will be held in Washington, D.C. from  the 10th-14th of December. Abstract submission closes on the 1st of August 2018 so get writing!

Sampling methane emissions from cows in Zimbabwe

The global burden of atmospheric methane has exhibited periods of both rapid growth and stagnation over the past two decades, with unexplained rapid growth since 2014. This growth has been accompanied by a negative isotopic shift (δ13CCH4), reversing the trend of the past two centuries. Methane does not have a single dominant source, but rather a wide spectrum of anthropogenic and natural sources. This diversity of uncertain sources has led to a number of recent explanations for recent growth including: tropical wetlands, livestock, fossil fuels (coupled with declining biomass burning), and changes in the methane sink (via reaction with OH). The warming impact of methane’s unexpected growth is now the largest deviation from the Paris Agreement. This session invites work that investigates processes controlling the methane budget using in situ measurements, satellite observations, and modeling, as well as the ways in which emissions can be reduced.