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The ocean’s abyssal floor is speckled with age-old stones, roughly the dimension of a closed hand, known as “polymetallic nodules.” In various locations, both along active and dormant hydrothermal openings and the deep sea’s ridges, volcanic arcs, and tectonic plate boundaries, as well as on the slopes of seamounts, other categories of mineral-abundant deposits that encompass high-demand minerals can be found.
The minerals extracted from the deep ocean are utilized to produce items such as lithium-ion batteries that power electric cars, mobile phones, or solar panels. In certain instances, the projected reserves of essential mineral deposits in sections of the abyssal ocean surpass global land-based inventories by several times.
“Society aspires for electric vehicles, solar panels for renewable energy, but all this necessitates resources,” states Thomas Peacock, a mechanical engineering professor at MIT, in a video elaborating on his study. “Resources on land are diminishing or becoming harder to reach. In certain oceanic areas, there exist vastly more of these resources than in terrestrial reserves. The question is: Can extracting some of these resources from the ocean be less detrimental than obtaining them from land?”
Deep-sea mining represents a novel frontier in mineral extraction, carrying potentially considerable consequences for industries and the global economic landscape, along with vital environmental and societal factors. Through rigorous investigative work, scientists like Peacock evaluate the ramifications of deep-sea mining activities methodically, supplying evidence for informed decision-making.
Mining operations, whether conducted on land or beneath the waves, can significantly affect the environment at various scales—local, regional, and global. With rising interest in deep-seabed mining fueled by skyrocketing demand for essential minerals, scientific research aids in uncovering the associated trade-offs.
Peacock has extensively examined the potential consequences of deep-sea mining in a Pacific Ocean region referred to as the Clarion Clipperton Zone (CCZ), where polymetallic nodules are plentiful. A decade prior, his research group initiated inquiries into deep-sea mining, recognizing a crucial need to establish monitoring and modeling tools to evaluate the extent of impact.
Currently, his MIT Environmental Dynamics Laboratory (ENDLab) is at the forefront of enhancing understanding of emerging ocean resource utilization technologies. Grounded in fundamental fluid dynamics, the team is innovating advanced monitoring strategies, groundbreaking sensors, and modeling frameworks.
“We are analyzing the characteristics of suspended sediment resulting from deep-sea mining operations, evaluating a new sediment sensor and another for turbulence, investigating the initial stages of sediment plume formation, and interpreting data from the technological trials conducted in the Pacific in 2021 and 2022,” he clarifies.
In the realm of deep-sea nodule mining, machines gather nodules from the ocean’s bed and transport them to a vessel above. Once the essential materials are extracted on the ship, some residual sediment may be reintroduced into the deep-water column. The resulting sediment plumes, and their possible effects, are a major focus of the team’s research.
A 2022 study performed in the CCZ examined the dynamics of sediment plumes in proximity to a seafloor polymetallic nodule mining vehicle. The trials demonstrated that the majority of the sediment-laden water released, between 92 and 98 percent, remained near the seabed, expanding laterally. The findings indicate that the dynamics of turbidity currents dictate the proportion of sediment that stays suspended in the water, along with the scope of the resulting ambient sediment plume. The significance of this process, previously overlooked, is considerable for plume modeling and provides insights for environmental impact assessments.
“Innovative model advancements can enhance our ability to make increasingly reliable predictions,” he asserts. The team also played a part in a recent study, published in the journal Nature, demonstrating that sediment deposited away from a test mining location is removed, likely by ocean currents, and reported any observed biological recuperation.
Researchers investigated a site four decades following a nodule test mining trial. While biological impacts on numerous organism groups were evident, populations of various organisms, including sediment macrofauna, mobile deposit feeders, and even sizable sessile fauna, had started to reform despite ongoing physical alterations at the seafloor. The study was spearheaded by the National Oceanography Centre in the U.K.
“A substantial amount has been gleaned regarding the fluid dynamics of deep-sea mining, particularly concerning sediment plumes,” states Peacock, noting that scientific advancements are ongoing with more results forthcoming. This work is establishing new benchmarks for in-situ monitoring of suspended sediment characteristics and for interpreting field data from recent technological evaluations.
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