ARVO preparation workshop

Blog post 3

ARVO preparation workshop

10 November 2026 | By Lennart Bach

The Alkalinity Research Voyage (ARVO) is a pan-Australian scientific study about the geochemical efficiency, environmental effects, and social and legal implications of so-called ocean liming. Ocean liming describes the acceleration of limestone weathering processes in seawater, which could lead to the removal of CO₂ from the atmosphere.

The ARVO team met on 9 November 2026 in Hobart, Tasmania, to plan and discuss ARVO1, the first of two voyages with the CSIRO research vessel (RV) Investigator. ARVO1 chief scientist Zanna Chase hosted the meeting at the Institute for Marine and Antarctic Studies (IMAS). The following points were addressed, and decisions were made where applicable.

1. ARVO aims to investigate how the Australian public evaluates ocean liming. This effort is led by Emily Ogier in collaboration with Kerryn Brent (CSIRO), Maree Fudge (UTAS), Tiffany Morrison (JCU), and Elly Harrould-Kolieb (University of Melbourne). We identified Political, Economic, Social, Technical, Environmental, and Legal (PESTEL) factors for the ARVO mission, an exercise that will be repeated later to see how ARVO changes the scientists' perspectives. Furthermore, we discussed the most relevant social dimensions that need to be studied in the context of ARVO.

   

2. ARVO needs to find a way to distribute 50 t of limestone in the surface ocean, a non-trivial task. The working group for the "distribution system" is led by Pete Strutton (UTAS) in collaboration with Michael Ellwood (ANU), Damon Britton (UTAS), and Lennart Bach (UTAS). The plan is to test limestone additions at different delivery speeds to test the dependency of critical factors, such as effects on zooplankton or alkalinity loss through secondary precipitation, on the density of particles in seawater. It was decided to use a "lawn mower" pattern while distributing most of the powder. Furthermore, it was decided that about 20% of the material would be added at a stationary location to enable study of how the limestone powder would be integrated into ocean sediments and affect biogeochemical processes therein.

   

3. ARVO research utilises numerical models to project how limestone powder moves through the water column after its delivery. This information is critical for planning the project. Likewise, ARVO aims to inform the same models to improve them and make them better at helping us understand the movement of particles, their potential dissolution, carbon uptake, and their potential environmental effects. The ARVO modelling team is led by Harris Anderson (CSIRO) in collaboration with Mathieu Mongin (CSIRO) and Tyler Rohr (UTAS).

4. To understand what happens to the limestone powder after delivery, we need to do a "budget". A budget describes the gains and losses of particles and their transformation into other forms, for example the transformation into alkalinity via particle dissolution. Likewise, we need to do similar budgets for dissolved parameters, most importantly alkalinity and carbon. This budget can be considered a synthesis of all processes that affect particles, alkalinity, and carbon. It was decided that the effort is led by Tyler Rohr (UTAS).

   

5. The delivery of limestone from RV Investigator means that a "plume" of limestone particles will occur directly behind RV Investigator. To capture the acute effects of the plume, we aim to hire Noctiluca, a small research vessel that belongs to UTAS. It was decided that voyage lead on Noctiluca will be Hanna van de Mortel (UTAS), who will study dissolution and, in the case of limestone, the more relevant process of secondary precipitation that may occur immediately after limestone additions.

   

6. To understand how the particle plume disperses and moves through the ocean after delivery, it is critically important to understand the physical conditions at the study site. The physical oceanography team is led by Claudio Cardoso (UNSW) and Nicole Jones (UWA). It was decided to use a range of observational tools to track the movement of the plume. A Triaxus will be used in a "figure-of-eight" pattern to observe the plume after delivery. Furthermore, a Wirewalker will be installed, and we will do regular CTD casts and deploy drifters. An aerial drone will observe the expected cloud of particles from above.

   

7. The ARVO environmental team is led by Katherina Petrou in collaboration with Robert Strzepek (UTAS), Kerrie Swadling (UTAS), Ruth Eriksen (CSIRO), Philip Boyd (UTAS), and Lennart Bach (UTAS). It was decided to use a staining technique to determine acute effects of particles on zooplankton and phytoplankton mortality. This will be conducted on board Noctiluca. Furthermore, incubation experiments with microcosms and mesocosms on board RV Investigator will inform potential changes in plankton communities. These incubation experiments are also used to assess the effects of alkaline materials other than limestone, such as calcium hydroxide, which are under consideration for ARVO2. Philip Boyd reported on progress to include observations of large animals, including seabirds, whales, sharks, and turtles, during ARVO.

8. The sediment team, co-led by Damon Britton (UTAS) and Helen Bostock (UQ), provided an update on their research plan. It was decided to take sediment cores before and after limestone additions to establish whether the limestone is detectable within sediments after delivery. Furthermore, the team discussed adding a commonly used sediment tracer to the material added at one location to study how the material could be moved through the sediment and whether it dissolves in acidic environments that can occur therein. Finally, it was decided to take sediment samples for incubation and to study how different alkaline materials dissolve in sediments and influence organisms living therein.

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