MOYA

The Kafue Flats Experience

michellecain

By Dave Lowry, Tim and Trish Broderick, Musa Lambakasa, James France, Stéphane Baugitte
Photos by Tim and Trish Broderick and Dave Lowry

The first ZWAMPS campaign consisted of both aircraft and ground surveys, these being linked most closely in the Kafue Flats region over the period Feb 2 to 5. The Kafue Flats are a floodplain wetland, extending from Itezhi-Tezhi Dam in the west, some 240 km east to Kafue town and never more than 50 km wide (https://en.wikipedia.org/wiki/Kafue_Flats). The river has changed course many times across its plain leaving scattered oxbow lakes and isolated snake-like sections of meanders to stagnate outside of flood season (Fig. 1).

Fig. 1 River Kafue lakes and meanders.

Fig. 1 River Kafue lakes and meanders.

The surveys and sampling commenced on Saturday with an intensive 4-hour zigzag flight over the region, designed by Keith Bower (Fig. 2), with elevated methane noted toward the eastern end near the start of the flight, before vertical mixing reduced these signals. The flight was very much enjoyed by Tim and our Zambian Ministry of Mines group, including Musa. Separating out the wetland source from the flight measurements and isotope data will be quite difficult because there were also numerous rural cattle herds and very extensive burning plumes producing methane (Fig. 3).

Fig. 2 End of the zig-zag flight

Fig. 2 End of the zig-zag flight

Fig. 3 Biomass burning plumes close to river

Fig. 3 Biomass burning plumes close to river

On Sunday we attempted to find our way by road to the northern margin of the Kafue Flats through the Blue Lagoon national park. After a 3-hour drive from Lusaka we reached a faded sign saying Nakeenda Lodge 9 km.  The national park sign was even more rusted. Soon we realised that this part of the park had not been visited for a long time as the track became more an overgrown and very muddy path, so we decided to sample air from a dambo in the pristine savanna (Fig. 4). The site was full of butterflies of numerous species, and even a praying mantis was catapulted into the car as we brushed past the luxuriant vegetation (Fig. 5).

Fig. 4 Stéphane directing air sampling

Fig. 4 Stéphane directing air sampling

Fig. 5 Mantis on water bottle

Fig. 5 Mantis on water bottle

Undeterred we decided to approach the park from the NW corner and reached a barrier. Here the head park ranger directed us to the managed game area and wetland.  After a few kilometres we turned off along a narrow track not on maps or GPS. Then followed 20 km over 90 minutes down a narrow and churned up track. As we passed across the invisible park boundary we came to a fishing camp on a rise above the floodplain and its associated biting insects. We were greeted by excited children and an ox cart (Fig. 6). Turns out that we were still some kilometres from the river, the resident lechwe antelope or the Game Ranger patrol camp. At this point we realised we had to get back to Lusaka before dark.

The return was no quicker, especially being interspersed with air sample collection in the pristine national park grassland (Fig. 7), as we carefully traced our way back along interweaving tracks using the GPS. We approached the outskirts of Lusaka as night fell, and on a road without lighting, carefully negotiated many minibuses without lighting and pedestrians bustling across the road to lively markets. Alarm bells had been ringing back at base when we failed to arrive back for the evening briefing and our Blue Lagoon destination was all that was known. As the city approached and phone reception returned we were able to let all know we had not broken down in the bush.

Fig. 6 Ox cart and children in the camp

Fig. 6 Ox cart and children in the camp

Fig. 7 Musa and Dave fishing for air

Fig. 7 Musa and Dave fishing for air

On Monday we had planned to sample on the south side of the floodplain, overnight in the Relax Hotel in Monze and then meet up with Mike Daly at the Lochinvar hot springs on Tuesday, but after breakfast Tim noticed that the Ford had a rear puncture from our toils the previous day, which fortunately hadn’t materialised on the evening drive back. Tim headed off hoping for a quick fix, but a brake fluid leak was also discovered from a distorted and corroded seal. Many discussions and calls later a replacement vehicle was delivered at 6 in the evening.

Plans quickly changed and the proposed rendezvous with Mike was scrapped due to the long distance, and the focus for Tuesday was to get into the sugar cane plantations and wetlands near Mazabuka. All was fine until about 2 hours into the drive when, on probably the steepest hill climb on the Kafue-Livingstone main road, there was a load bang from the rear of the vehicle. This time a major blow out and a 3 cm long rip in the tyre. Tim and Musa got to work on the jack while we jammed the other wheels with some lovely roadside calc-silicate boulders. Convoys of lorries heading for Botswana and South Africa laden with copper and other goods struggled past us. It soon became apparent that the supplied jack was not high enough for our Landcruiser, but we managed to flag down a local farmer and get the change done.

That’s when we noticed a 1cm diameter, perfectly round hole through the alloy wheel below the rip in the tyre, with a very clear entry and exit direction from a high velocity impact (Figs. 8 and 9). None of us had seen anything like that before and we still don’t know the cause, so we will leave this to your imagination.

Fig. 8 Hole in the alloy wheel – inside view

Fig. 8 Hole in the alloy wheel – inside view

Fig. 9 Hole in the alloy wheel – outside view

Fig. 9 Hole in the alloy wheel – outside view

At Mazabuka we found a tyre repairperson and then followed a wild goose chase to find a welder, then through sugar cane plantations to a market for electrodes, which then didn’t work because the alloy was wrong and required a DC current. After 2 more lost hours, we had a reality check, dumped the wheel and tyre into the back and decided to risk it on the spare and take the 30 km of dirt tracks NE toward the wetlands and river. With co-ordination of aerial images and GPS we headed down a narrow track and finally came to lush vegetation, reed beds (bulrushes) and clusters of water lilies, before the track stopped abruptly in a small clearing populated by a group of fisher folk. We proceeded to collect air samples from different heights in the reed beds. In the midst of this the reeds seemed to part and a small canoe cruised into the bank laden with good-sized Kafue bream (Figs. 10 and 11).

Fig. 10 Boatmen in the reed beds

Fig. 10 Boatmen in the reed beds

Fig. 11 Cargo of Kafue bream

Fig. 11 Cargo of Kafue bream

The drive back was far less eventful. The next morning the car hire people inspected the wheel and seemed overly keen to give us our deposit back and get us on our way. We can certainly look back on a couple of eventful and somewhat surreal days that we won’t forget in a hurry and hope that the few highly prized air samples were well worth our efforts to collect them.

Papyrus: a methane emitter and natural wind vane

michellecain
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.

 

Banned industrial solvent sheds new light on methane mystery

moya Leave a comment

This news post is about exciting findings by Matt Rigby and co-authors, which may hold the key to the sudden and unexpected global rise in atmospheric methane following almost a decade in which concentrations had stayed relatively constant. Below is press release published by the University of Bristol on this recent paper: ‘The role of atmospheric oxidation in recent methane growth’ by M. Rigby et al in Proceedings of the National Academy of Sciences

Model simulation of the hydroxyl radical concentration in the atmosphere.

Since 2007, scientists have been searching to find the cause of a sudden and unexpected global rise in atmospheric methane, a potent greenhouse gas, following almost a decade in which concentrations had stayed relatively constant.

Recent studies have explored a range of possible causes. Suggestions have included a rise in oil and natural gas extraction, increased emissions from tropical wetlands or increases in emissions from growing East Asian economies.

However, a new paper by an international team of scientists in the Proceedings of the National Academy of Sciences (PNAS) investigates an alternative possibility: a rise and fall in the concentration of the substance that destroys methane in the atmosphere, the hydroxyl radical.

Lead author, Dr Matt Rigby from the University of Bristol’s School of Chemistry and Cabot Institute, said: “A change in the hydroxyl radical concentration would be a neat explanation for the changes in methane that we’ve seen.

“It would mean that emissions may not have increased suddenly in 2007, but rather, risen more gradually over the last couple of decades.”

Since the global concentration of the hydroxyl radical cannot be measured directly, the team’s findings were made by studying the rate at which the solvent methyl chloroform, which is also destroyed by hydroxyl, was removed from the atmosphere.

Professor Ron Prinn from the Massachusetts Institute of Technology, who co-authored the paper and leads the Advanced Global Atmospheric Gases Experiment (AGAGE), an international project that measures greenhouse gas concentrations, said: “We have been monitoring trends in the methyl chloroform for nearly 40 years because of its role in depleting stratospheric ozone.

“Because methyl chloroform is now banned under the Montreal Protocol for the Protection of the Stratospheric Ozone Layer, we’ve see its concentration drop very rapidly.

“We can examine how this rate of decline changes from one year to the next to infer the hydroxyl radical concentration.”

Dr Steve Montzka from the National Oceanic and Atmospheric Administration (NOAA), who also co-authored the paper, and operates an independent measurement network for methylchloroform, added: “This paper re-examines some of the assumptions that had previously been made in studies of hydroxyl radical and methyl chloroform and shows how they influence our understanding of methane’s atmospheric sink.

“To me, one of the main findings is that our objective analyses of two sets of observations tells essentially the same story, even as it becomes more and more difficult to measure methyl chloroform given that its concentration is approaching zero.”

Dr Rigby added that there was still uncertainty remaining. He explained: “Whilst there are strong hints in our study that hydroxyl radical changes could be playing a significant role in the fluctuations in methane growth, our uncertainties are very large.

“In future, we need to think about new ways to reduce this uncertainty, if we are to truly understand changes in atmospheric methane.”

The study also lead to a more certain, but unexpected finding: that emissions of methyl chloroform had not dropped to zero.

Dr Rigby said: “Because its production is now banned globally, we were expecting to see no emissions of this substance at all. However, we have very strong evidence that emissions are continuing.”

The team are preparing a follow-up study that would determine where these emissions are originating. Meanwhile, they are continuing to monitor methane in the atmosphere, and are waiting to see whether its current rate of increase will continue.

Project MOYA – NERC’s study of the global methane budget

moya Leave a comment

In 2016, NERC began support for Project MOYA, a major study of methane in the Earth’s atmosphere. MOYA – or Methane Observations and Yearly Assessment – is a major consortium between 14 UK universities and Research institutions, brought together as a NERC highlight project to study methane in the global atmosphere. “MOYA” means ‘wind’ or ‘breath’ or ‘spirit’ in some southern African languages, appropriate for a project focused on methane, part of the breath of the biosphere.

Methane, or CH4, is a very important greenhouse gas, second only to carbon dioxide, CO2, in its contribution to human-induced global warming. Its overall warming impact since human industrialization began is more than half that of CO2, but it has had much less attention from policymakers.

Molecule for molecule, methane is a much stronger greenhouse gas than CO2 but, in contrast to CO2 emissions, which effectively increase the amount in the air for centuries, methane is only in the air for less than a decade before it is oxidized to CO2. Thus effective measures to bring down methane will have rapid impact – it is a very attractive target for emission reduction efforts.

Methane emissions are both natural and human-induced sources. Major natural sources are the great tropical, boreal and Arctic wetlands of the world, including the equatorial Amazon and Congo wetlands, the seasonal savanna swamps such as those in Bolivia, Paraguay, Zambia, South Sudan, etc, and, in summer, the vast wetlands of Canada and Siberia.

Papyrus swamp, Kajjansi, Uganda. Equatorial swamps are major methane emitters.

Photo Credit: EG Nisbet.
Papyrus swamp, Kajjansi, Uganda. Equatorial swamps are major methane emitters.

Human sources include gas leaks from the natural gas industry (gas is mostly methane), the coal and oil industries, and also from biomass burning, as well as waste disposal landfills, and sewage plants. Ruminant animals, which ferment plants in their foreguts, are major emitters – cows, water buffaloes, sheep, etc. (note it’s from the front end of the cow: ‘bovine eructation’ – not much is from the flatulent end!). The main sink of methane is atmospheric OH (water minus a hydrogen) in the air, especially in the brightly sunlit tropical atmosphere a few km above sea level. Soils also removes methane, as does chlorine from sea spray.

There is much uncertainty about the methane budget, as we don’t know how much methane is being made. So called ‘bottom-up’ inventories, made by totaling up all the local estimates of emissions, are significantly larger than ‘top-down’ studies made by measuring how much methane is actually in the air. But a great deal of methane is certainly emitted. In comparison to CO2, which has only gone up by a factor of somewhat over a half since King George III ruled Britain and North America, the amount of methane in the air has increased by about two and a half times.

Canadian wetland, near Fraserdale, Ontario. Boreal wetlands like this, often made or enhanced by beaver dams, are very extensive and emit much methane in summer.

Photo Credit: EG Nisbet.
Canadian wetland, near Fraserdale, Ontario. Boreal wetlands like this, often made or enhanced by beaver dams, are very extensive and emit much methane in summer.

In the 20th century, methane grew rapidly, but by about the year 2000 it had effectively attained equilibrium in the air, with sources matching sinks. During the rapid growth in the 20th century, the proportion of the carbon-13 isotope in the methane in the air had increased steadily. Now carbon-13 is somewhat richer in industrial gas and gas from fires, while carbon-12 is preferred by biological processes, so the carbon 12:13 ratio of methane is a powerful way of finding out where the methane came from. Methane from fires and fossil fuel leaks is somewhat richer in C-13 (‘heavy’), while methane from swamps and cows is slightly more C-12 rich (‘light’).

Atmospheric methane concentrations have increased sharply since 2007, and dramatically in 2014, 2015 and 2016, with especially strong growth in the tropics. Simultaneously, the methane in the air has become more depleted in carbon-13 relative to carbon 12, which implies that the cause of the growth is not emission of methane from fossil fuel industries such as natural gas or coal, nor is it emitted from biomass fires. Methane’s growth is now so significant that is threatens to make it much more difficult to keep global warming below the 1.5oC goal and 2oC target of the United Nations’ Paris Agreement signed in 2015.

We do not fully understand why methane is growing so fast. It may be that tropical wetlands are emitting much more methane? Or perhaps tropical cows are breathing out more? Or has the largest methane sink, which is atmospheric hydroxyl, changed so that destruction of methane has reduced?

– Professor Euan Nisbet, Principal Investigator for MOYA, Royal Holloway University of London

Photo Credit: EG Nisbet.
The methane kill zone, in the moist tropical mid-troposphere, where the main sink, OH, destroys methane.

More information about the project

Project MOYA is NERC’s ‘Highlight’ study, designed to answer some of the questions around methane. The focus is the Global Methane Budget – finding out methane’s sources and sinks, and what controls its growth. The 14 partners include Univ. East Anglia, Univ. Exeter and Plymouth Marine lab, British Antarctic Survey, Univ. Manchester, Univ. York, Univ. Leicester, NERC Centre for Ecology and Hydrology, Open Univ., Univ. Aberdeen, Univ. Leeds, Univ. Bristol, Univ, Cambridge, and the National Centre for earth Observation and Univ. Edinburgh. The project is led by the Earth Science Dept at Royal Holloway, Univ. of London. It is a follow-up to NERC’s recent highly successful MAMM project, studying the methane budget of the Arctic.

There are various parts to MOYA – observation, field process studies, and computer modelling of the global budget.

Better Observations are needed to derive estimates of emissions. The project will support a wide observation network for methane and its isotopes. Continuous stations will be at Kjolnes (Norway), Weybourne, Jersey, NERC ship RRS JC Ross, Cape Verde, Ascension, Falklands, Halley Bay, and Hong Kong, with associated stations in Canada, Spitsbergen, Bolivia, South Africa, India, Rwanda and Malaysia. Flask or bag sampling (for methane, 13C and D/H isotopes) will also be undertaken at these stations and at a number of continental stations in S. America, Africa and S, SE and E Asia, with offline analysis in the UK.

In addition, the UK FAAM aircraft will carry out flights across the Atlantic tropics, from Azores to Cape Verde to Ascension.

In parallel to the observational work, field campaigns will be carried out to study emissions hot spots. Field campaigns will be undertaken in tropical wetlands in Amazonia, Africa, India and SE Asia, and in the great savanna grassland regions where intense seasonal dry season biomass burning occurs. Land surface modelling will also be improved, so we have a much better understanding of which types of plants grow where, and why. Work will also be carried out to identify industrial emissions, and develop ways of reducing them, to help the Paris Agreement reach its target.

To interpret all these data inputs, MOYA will also support major computer modelling studies, to work out how much methane is being emitted in each region and across the planet as a whole, to test and improve the top-down and bottom-up emission estimates, and to try to find out why methane is increasing.

Reference:

Nisbet, E. G., et al. (2016), Rising atmospheric methane: 2007–2014 growth and isotopic shift, Global Biogeochem. Cycles, 30, doi:10.1002/ 2016GB005406.
http://onlinelibrary.wiley.com/doi/10.1002/2016GB005406/epdf (PDF, open access)