Home | Webinars | OceanICU – Webinar 5 – Industrial Carbon and Mining

OceanICU - Webinar 5 - Industrial Carbon and Mining

Interest in the mining of metal ores (polymetallic nodules, massive sulphides, and ferromanganese crusts) from the abyssal seabed has been sparked by the projected future demands of metals for the transition to a low-carbon energy system and the increasing consumption of high-tech products in conjunction with global population growth. While extracting metals from deep-sea ores may contribute to the desired overall reduction of our CO2 emissions, it will certainly introduce a new environmental threat to our ocean.

This webinar discussed our current state of knowledge on abyssal ecosystems and the expected impacts from future deep-sea mining activities, with a focus on polymetallic nodule areas, and presented research results drawn from benthic impact results conducted in the 1990’s and recent industrial mining trials. The presentation also touched upon the ongoing development of regulations for the exploitation of mineral resources in the Area by the International Seabed Authority.

If you missed the webinar, check out the video recording and the presentation here and scroll down for a transcript of the questions and answers.


Richard Sanders

Coordinator of the OceanICU project

Richard is the lead coordinator of the OceanICU project. He has worked since 2019 at NORCE in Bergen as Director of the Ocean Thematic Centre within the ICOS research infrastructure. This involves helping the surface ocean pCO2 observing community within Europe make the highest quality observations and in establishing more secure funding routes for surface Ocean C observations.  Prior to his move to Bergen he served as Chair of the Ocean Biogeochemistry and Ecosystems Research Group in the UK National Oceanography Centre. He holds an honorary chair in Ocean Biogeochemistry at the  University of Southampton in the UK. 

Matthias Haeckel

GEOMAR Helmholtz Centre
for Ocean Research Kiel

Matthias Haeckel is a marine biogeochemist at the GEOMAR Helmholtz Centre for Ocean Research Kiel. He holds a PhD in Natural Sciences from Kiel University. In his research, he combines sea-going fieldwork with numerical modelling and high-pressure experiments to entangle and quantify biogeochemical processes and how they are altered by anthropogenic uses of the ocean, such as methane hydrate exploitation, oil & gas production, sub-seabed CO2 storage, deep-sea mining. Since 2015, he has been coordinating the large collaborative European project MiningImpact on the environmental risks and impacts of deep-seabed mining. For OceanICU, he is leading WP5 on how industrial processes affect the marine carbon cycle.

Questions from the Audience

Answered by Matthias Haeckel

These types of experiments will be more challenging to conduct.  A solution could be Autonomous Underwater Vehicles (AUVs) could be deployed to collect information at different water depths. This would allow for research to be conducted in three dimensions compared to the current work being done in two dimensions with equipment that is confined to the seafloor. .

Global Sea Mineral Resources (GSR) the deep sea exploratory division of the Deme Group, is aiming at testing their next collector stage around 2027, which will include a riser system to transport the nodules to the surface and re-inject the wastewater stream. We hope to be at the site to do the monitoring when this test happens.

 We have elevated particle concentrations, leading to flocculation and increased sinking of particles and scavenging of natural particles from the water column. Therefore, I would expect that we get an increased export of organic and inorganic matter to the seafloor with the re-injection of a wastewater stream.

It is critical to regulate at which water depth the re-injection of this wastewater stream is allowed to take place. If the re-injection of waste water is done in the surface waters, where we have most phytoplankton and zooplankton, we can expect that the impacts –at least on a regional scale— will probably be severe. However, if the re-injection takes place below two or three km deep, the impact on the carbon cycle process will be much smaller. This is because typically 98% of the organic carbon has already been re-mineralized by the time it reaches depths of two to three km.

In terms of the particle concentrations we measured, those in the far field were still significantly higher than the background concentrations—about 10 to 100 times higher— reaching several hundred micrograms per litre. However, we don’t know whether this has a significant impact. These findings align with sediment plume dispersion modelling research conducted in studies 20 to 30 years ago, which predicted that around 95% of the particles would settle within a few hundred metres, leaving approximately 5% in suspension for a period of weeks, months, or possibly even years. What we observed was a limited mixing of this sediment plume with the surrounding bottom waters within distances of a few kilometres. These results were surprising and suggest that these high particle concentrations behave as a dense gravity flow and remain relatively distinct from the surrounding water mass.

The release of the metals into the water column was a surprising result in our study. What remains unclear is the duration for which these metals persist in dissolved form. It’s important to note that dissolved metals generally exhibit a higher toxicity compared to solid metals, as demonstrated in ecotoxicity studies. Investigating the time frame during which these metals remain in their dissolved state and in situ ecotoxicity studies on deep-sea fauna are the critical next steps.

Further research into ecotoxicity is imperative, but it presents significant challenges. Successful transfers of live deep-sea fauna to the surface have not been achieved due to the depressurization effects that the fauna does not survive, making it essential to conduct ecotoxicity studies directly in the deep ocean. Existing experiments on the impacts of polymetallic nodule mining have largely focused on shallow water species, which are often used to higher metal concentrations in their natural environment, leaving uncertainty about the applicability of these findings to deep-water organisms. Therefore, understanding the ecotoxic effects of deep-sea mining requires dedicated research conducted in situ, where deep-sea organisms naturally reside.

Another critical area requiring further research involves understanding of the species connectivity in deep-sea ecosystems. Will disturbances caused by nodule mining result in the separation of populations, thereby disrupting genetic connectivity between different populations? We do know that species exhibit connectivity over vast distances, spanning thousands of kilometres across the entire Clarion-Clipperton Zone (CCZ), and for some species, this connectivity extends across the entire Pacific Ocean. The potential consequences of deep-sea mining on this species connectivity remain largely unknown, but are critical for assessing far-reaching and long-term consequences of deep-sea mining.

Furthermore, we lack a comprehensive understanding of the ecosystem dynamics in the deep sea, particularly regarding the food web and the connections between the benthic and pelagic systems. Many questions remain unanswered in terms of how these interactions and relationships function.

The particle size range in the plume in the Global Sea Mineral Resources (GSM) area that was observed with a particle camera was 61-313 micrometres (D25-D75 range), the smallest detected particles were 15 micrometres (Gazis et al., accepted, Nature Communications).  Grain size analyses of sampled plume material are still ongoing.

In addition to the answer to Q6, it is also important to establish threshold values of suspended particle concentrations and thickness of depositional blanketing impacting the pelagic and benthic fauna and the ecosystem functioning.

Our recommendation is to only permit injection of the waste discharge at the seafloor – as scientists have suggested already 25 years ago. Injection into the upper 1000-1500 m should certainly be forbidden.

 I do not know if the industry is looking into this. There have been lab experiments on flocculation in general and in the context of deep-sea mining. Colleagues at BGR (Geological Survey of Germany) have studied how adding carbonates (they are known to do this) increase flocculation of suspended Clarion-Clipperton Zone (CCZ)  sediment in the lab. However, the additional environmental impacts of adding flocculants to the suspended plume can also create other environmental impacts (e.g. toxic effects) and legally this may possibly fall under dumping (for the waste discharge). The heated debate on adding dispersants into oil spills may be a helpful example in this discussion.

The Metals Company is conducting research in the area directly adjacent to the BGR (Geological Survey of Germany) contract area. I have watched one or two of their webinars but the information they have provided is limited. I’m looking forward to more detailed information to be able to compare my findings with theirs.

This depends on the location of the mining operation. For the Solwara project In Papua New Guinea impacts on fishing and tourism was debated. In The Clarion-Clipperton Zone (CCZ) fishing may be impacted – Van der Grient and Drazen published a paper on this issue last year.

For mining of polymetallic nodules (containing oxidized metal species) this may be the case, but for seafloor massive sulphides (containing reduced metals) this is likely different. In addition, we also need to consider cumulative impacts from both (and additional) effects. Overall, we need to establish the ecotoxicity in situ as discussed earlier (see answers to Q5 and Q6).

Answered by Richard Sanders

What would we view as a significant negative impact? I’m uncertain how to quantify that. My perspective is that we can do lots of great work around different processes. But the the question of what we view as significant and sort of, by implication, tolerable, is for regulators in the industry to determine based on the research. 

Ultimately I think we need to think through the implications of this emerging field in much more detail than we are doing at the moment. In fact, one of the activities within OceanICU is to rank the importance of these various biological carbon pump processes, in particular the ones that we think are sensitive to these large scale sediment injection processes. This way we can begin to get an understanding of what the implications are for the biological carbon pump.