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Research Interests
Research Interests
Polymetallic nodules lying on the deep seabed.
My key research question:
My key research question:
What are the environmental effects of deep-seabed mining, and how do we mitigate and control these impacts in the event of commercial deep-seaned mining?
More questions...
More questions...
What are the physical processes that govern the behaviour of sediment clouds and plumes produced near deep-seabed mining sites?
How can we improve models of how these clouds pollute the water column, both physically and chemically via dissolution?
How can oceanographic and biogeochemical modelling techniques be employed to predict how these environmental stresses will spread in the oceans?
What scientific methods and techniques are viable for real-time monitoring of commercial deep-seabed mining?
How do we ensure that companies adhere to self-verification measures and thresholds set by the International Seabed Authority?
Understanding deep-seabed mining Particle plumes
Understanding deep-seabed mining Particle plumes
1. Turbulent mixing at the source of collector plumes
1. Turbulent mixing at the source of collector plumes
When deep-sea mining vehicles pick up polymetallic nodules, they get rid of waste sediment they pick up at the back of the vehicle. This produces something called a turbidity current that spreads sideways away from the vehicle.
These 'collector plumes' increase concentrations of sediment in the water column, and redeposit sediment around the vehicle's path. The physics of this type of particle-laden fluid flow are still an active area of research.
In this work I used lab lock-release experiments to test how the trade-off of sediment concentration and turbulent mixing at the source of this plume change the shape and speed of collector plumes.
We found that as sediment concentration gets lower, you need less vigorous mixing and turbulence to cause a "burst" behaviour that causes increases in height and volume. There is therefore a trade-off between reducing sediment delivered, and keeping the turbulence low enough to avoid this behaviour.
Paper in review, hopefully coming soon!
2. Separation of particles from midwater plumes
2. Separation of particles from midwater plumes
During deep-seabed mining of polymetallic nodules, a slurry of fine seabed clays and broken up metal-rich rocks will be pumped back into the ocean at a depth of around ~2000 m as a waste product.
This 'midwater plume' will spread as a negatively buoyant plume but is also energetic at the source (which is called a jet). The particles will separate and sink out of the fluid that initially carries them, and the whole thing will also interact with whatever the currents in the ocean happen to be doing at that location.
We need to understand the physics of flows so we can predict where this metal-rich mixture will end up in the ocean.
During my Masters in 2020/2021 I studied the physical behaviour of this type of mixture using particles of different sizes and dyed fluids.
Our main findings are that once particles are large enough (and therefore move fast enough) they will separate from the plume fluid and sink. However, for particles that sink at a speed roughly slower than the current speed, they will remain mixed into the initial fluid for longer.
MONITORING OF DEEP-seabed mining activities
MONITORING OF DEEP-seabed mining activities
3. Self-GOVERNANCE and self-reporting of mining activities
3. Self-GOVERNANCE and self-reporting of mining activities
Deep-seabed mining activities will likely happen in the most remote and inaccessible places on our planet: over 1000 km from the nearest continental land mass, and 6000 m beneath the water surface with pressures up to 750 x atmospheric.
These remote and inaccessible conditions mean that monitoring the environmental impacts of mining activities will essentially be self-reported by the companies that are doing the mining, as they are the only people who have the technology to reach these locations and monitor the environmental changes that occur.
In this article, we argue that this framework of "self-governance" fails to respond to the needs for a proactive assessment of environmental impacts. We also highlights some structural limitations of the draft regulations, guidelines, and standards, including vaguely defined terms that could constitute major challenges once the industry enters its production cycle.
Read the paper here!
4. How do we decide the "best" technology for monitoring?
4. How do we decide the "best" technology for monitoring?
In the International Seabed Authority (ISA) Regulations, Standards & Guidelines for the new industry of deep-seabed mining, the phrases "Best Available Techniques" and "Best Environmental Practices" are used over 50 times. Specifically in guidance for environmental management and monitoring plans, the ISA advises monitoring practices based on these "Best" techniques but doesn't say specifically what technology to use.
However, is no workflow for contractors to quantitatively demonstrate on what basis a technology is deemed “best” for measuring a given indicator.
In this project, I am devising a repeatable workflow to identifying the best possible technology for a given measurement, indicator or threshold.
The method considers trade-offs in quantitative and qualitative criteria to identify the “best” available technology for monitoring deep-sea mining indicators and thresholds. The goal is to make transparent the decision making process when selecting monitoring technologies and create a standardized framework that is independent of specific environmental indicators, transparent, and repeatable.
This is a work in progress!
Publications
Publications
C.B.G.James, A.M.Jellinek, H.S.Topf (in review)
How source momentum and particle loading shape deep-sea mining collector vehicle discharges.
Submitted to Elementa: Science of the Anthropocene.
R. Deberdt, C.B.G. James (2024)
Self-governance at depth: The International Seabed Authority and verification culture of the deep-sea mining industry.
Resources Policy, 89, 104577.
C.B.G. James, N. Mingotti, & A.W. Woods (2022).
On particle separation from turbulent particle plumes in a cross-flow.
Journal of Fluid Mechanics, 932, A45.
If you have any issues accessing these publications, please feel free to email me for a PDF copy.
Presentations and Posters
Presentations and Posters
2026 – Trade-offs in deep-sea mining plumes: effects of sediment concentration and release turbulence
Ocean Sciences Meeting 2026, Glasgow UK.
2026 – (Poster) How do we identify the best available technologies for monitoring deep-sea mining impacts?
Ocean Sciences Meeting 2026, Glasgow UK.
2022 – Deep-sea mining: green energy solution or environmental nightmare?
UBC Earth Ocean and Atmospheric Sciences, Graduate Seminar Series.
2022 – Environmental impacts of deep-sea mining.
University of British Columbia, Undergraduate seminar-in-science lectures.
2021 – Modelling sediment transport during deep-sea mining.
University of Cambridge, BP Institute for multiphase flow, Weekly department seminar.
2021 – (Poster) Modelling sediment transport during deep-sea mining.
University of Cambridge, Sedgwick Club Conference.
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