Tom Chalk

Scooping out oceanic CO₂ to make room for more

#CNRSNews 📰 Scientists have set up standards for marine CO2 removal, which could enable extra oceanic storage of carbon dioxide and its recovery as carbonate or biomass. Yet further research is needed prior to large-scale implementation

#exocean advent calendar day 24!
Today we thought it was a good fit to show an image/talk about “conception”…
One of the thing we (try to) do best at ExoCean is planktonic foraminifera reproduction. Here two immaculate mummies… 😏

We would like to wish you all a beautiful Christmas Eve!

HMS Challenger

#exoCeanadvent Day 23: at exoCean we also look at some old questions: in the late 1800s, during the HMS Challenger expedition, they discovered that you can have a constant rain of shells from above, and still end up with a seafloor that looks like the carbonate budget never existed. Why? Pressure. 🌊

More politicians, policymakers, and companies should be on Bluesky.

Postdoc Matthieu Buisson loads samples into the rack ready for elemental analysis.

#exoCeanadvent Day 22: Winding down for the holidays often means one thing... more mass spectrometry time is available! With our friends in @cerege.bsky.social's #ENVITOP facility, we're making use! Thanks to their equipment we're working on measuring elemental compositions down to the nano-gramme!

#exocean advent calendar Day 21! The strongest link between all of us is our love for the ocean. Leaving Marseille with a magnificent sunrise reminds us each time we go out how lucky we are to do what we love for a living!
We already have our ship time for the first 6 months of 2026 - exciting!

Here's to #2026! Please don't hold us to any of these...

12 scientific papers 💻, 11 months of good weather 🌞, 10⁴ foram babies 🐚, 9 visiting scientists 👩🏼‍🔬👨🏾‍🔬, 8 successful boat missions 🛥️, 7 website visits 🙏🏼, 6 new hypotheses 💡...*5 gold rings*...4 defended masters 📜, 3 #ForCry mass spec methods 🔍, 2 #Deep-C reactors 🧿...

glorious peacock seducing CEREGE people

please feed me

we love peacocks so much they follow us in our offices

#exoCeanadvent Day 19: Friday edition: today’s post is about the peacocks at CEREGE, because it’s Friday and our brains are in weekend mode. They wander around like they own the campus, scream for no reason, and block paths with absolute confidence. Honestly, goals. 🦚

Essential reading for those interested in going carbon negative 👀. See what @sulpis.bsky.social does for a living and how it connects to @exoceanlab.bsky.social here!

Read the European Marine Board report here: 📘👀
www.marineboard.eu/publications...

Net accident you say? Ooops, this net came back looking like it had been mauled by a shark, and I think... Maybe it had. A good, but expensive(!) sample. Sorry @tdegaridel.bsky.social!

Jaime introduces his project and ForCry at a team seminar in Mainz. 📷 S. Chaabane

#exoCeanadvent Day 16: We're getting closer to the holidays, but we don't stop yet. @erc.europa.eu postdoc @jysuarezibarra.bsky.social was out today presenting his work @maxplanck.de in Mainz. @soniachaabane.bsky.social is also visiting to chat with colleagues.

A rack of tiny samples, about 0.5mm in diameter... Here we've custom made some really clean rings to hold them in place... next step, freeze!

#exoCeanadvent Day 15: Some plankton are tiny [citation needed?], and for those we need ways to measure tiny (this is a theme you'll hear us talking about a lot). Sometimes just holding samples in place can be hard.... enter the #Cryostage! ❄️

Sometimes you can replace a boat trip with a car trip, ever wondered how much ocean you can get into a Golf?

#exoCeanadvent Day 14 Footprint reduction: we do lab-based ocean science because we genuinely love it, but also because lab experiments can replace lots of field trips. More control, more insight, and in part, fewer emissions. Bonus: dissolving old sediment cores neutralizes a bit of CO2. 😇

#exoCeanadvent Day 13: Time Machine. Travel back in time with us 6 million years. Part of the reason for our work @exoceanlab.bsky.social is to better understand the past through observing the modern, but sometimes you just need some ancient mud..@chalkyoceans.bsky.social recently went to get some!

The exoCean team and friends actively brainstorming on hot topics

Tiny raclette pan, big ambitions

#exoCeanadvent Day 12: End-of-year celebration - raclette edition. On the agenda for this team meeting: cheese, cheese, cheese, goals for next year: even more cheese. We’ve officially reached our melting point. 🧀

#exoCeanadvent Day 11: Science makes you do strange things. Meet @astridhylen.bsky.social, a postdoc working with carbonate dissolution in coastal sediments. She recently found herself in the middle of a salt marsh, stirring one of the ponds with a (clean) toilet brush taped to a curtain rod.

Correct! That will come later. I thought I added alt text, but that seems to have disappeared.

There's still much more to come from our trip to Bermuda with @juliemeilland.bsky.social, @thefosterlab.bsky.social and @case4climate.bsky.social. Whilst there, we were all tortured with video interviews... Here's a taster!

100% recommend for fieldwork. See @maxime-felix.bsky.social for details on availability.

Don't eat that! A large foraminifera trying to eat grains of olivine. It soon realised that they weren't food, but had no problems afterwards, so... not poison!

#exoCeanadvent Day 9: Meet Maxime (again). At @exoceanlab.bsky.social and @climatecerege.bsky.social Maxime has been conducting several experiments focusing on the culture of marine organisms. One project involved culturing foraminifera in the presence of olivine (Mg,Fe)2SiO4, an igneous mineral.

One of many super cool projects started or starting in @exoceanlab.bsky.social. Keep it up Katoo!

Schematic of the Deep-C high-pressure reactor and in situ sensors.

#exoCeanadvent Day 6: To study the deepest ocean trenches, we’re building reactors that make our lab behave like the deep ocean. Funded by @erc.europa.eu #Deep-C, they will hold cold seawater at ~1000 bar (10km water) so we* watch pressure shape chemistry and biology 🔬🌊

*mostly @sulpis.bsky.social

A schematic graph showing global temperature, plotted against CO2. We know CO2 increases temperature, but the how far and how fast are still not totally constrained. Tipping points, or sensitivity changes could impact this relationship in the future, and may have done in the past.

#exoCeanadvent Day 4: Why did we set up this lab? Part I. What is going to happen to climate as CO2 levels go up? @chalkyoceans.bsky.social and @erc.europa.eu project #ForCry look at CO2 in the past to better understand climate sensitivity. Part of this is making better past CO2 reconstructions.

Find this data, and more - in the fantastic paper by Elwyn de la Vega. Boron isotope CO2 reconstructions in the Pleistocene have come a long way... but we still have more to come. Watch this space with @mudwaterclimate.bsky.social and many others!

cp.copernicus.org/articles/19/...

It might have been 10 years @whoi.edu, but I still wear your hoodie at sea. Thanks for helping me know what to do when I'm there.

A jar of deep sea mud sitting on a height adjustable stand. It has microprobes to measure oxygen (respiration, photosynthesis) and pH (dissolution, precipitation, also respiration etc...) at tiny intervals to see what is going on right at the grain interface.

Here comes the final boss: porewater microprofiles, using our favourite tools, pH and oxygen microsensors, made of glass and pure anxiety. Every time one snaps, we just sigh, call our finance manager, and prepare our next monthly order from @unisense.bsky.social. Thanks for the tiny sensors!

Marine and Olivier cutting the core into slices, at the top it can be really liquid and gooey, so we keep it vertically, but lower down it can be almost like a rock. Despite the complaining from Olivier both of them are remarkably mud-free!

Once the cores make it back to our lab, it’s time to get our hands dirty: we slice them like a very unappetizing cake, a couple of cms at a time. If we can, outside of the lab to keep it clean inside. All of that just to rebuild the sediment as it looked on the seabed.

Tom holding a surface interface core, like a proud father. The core includes the top layer of mud, with the bottom layer of ocean, including all the creatures living there (and more importantly for Tom, the ones long dead too). Disclaimer: Tom does not get seasick.

#exoCeanadvent Day 4: At exoCean we also investigate what happens to calcifiers who mysteriously die (answer: a lot happens). For that we must go at sea and collect evidence, just like CSI but with more seasickness pills, same sunglasses.