Discharge and surface plume measurements during manganese nodule mining tests in the north equatorial pacific

Lavelle, J. W.; Ozturgut, E.; Baker, Edward T.; Swift, Stephen A.

doi:10.1016/0141-1136(82)90050-2

Cited by 11 publications

(8 citation statements)

References 5 publications

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“…operation would discharge a total of~1.2 × 10 8 kg of sediment (M s ) and~6.1 × 10 7 kg of fines (M f ) into the ocean per year. The particle size of the discharged nodule fines depends on the separation process applied prior to the discharge; a three stage separation system is expected to result in the discharge of nodule fines within the same size class of the discharged seafloor sediments 51 , with nodule fines consisting of manganese oxides and iron oxyhydroxide particles that are thermodynamically stable in oxygenated seawater 52 . There is currently no evidence that dissolved metals would be released along with the sediments and fines.…”

Section: Discussionmentioning

confidence: 99%

Extent of impact of deep-sea nodule mining midwater plumes is influenced by sediment loading, turbulence and thresholds

Muñoz-Royo

Peacock

Alford

et al. 2021

Commun Earth Environ

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Deep-sea polymetallic nodule mining research activity has substantially increased in recent years, but the expected level of environmental impact is still being established. One environmental concern is the discharge of a sediment plume into the midwater column. We performed a dedicated field study using sediment from the Clarion Clipperton Fracture Zone. The plume was monitored and tracked using both established and novel instrumentation, including acoustic and turbulence measurements. Our field studies reveal that modeling can reliably predict the properties of a midwater plume in the vicinity of the discharge and that sediment aggregation effects are not significant. The plume model is used to drive a numerical simulation of a commercial-scale operation in the Clarion Clipperton Fracture Zone. Key takeaways are that the scale of impact of the plume is notably influenced by the values of environmentally acceptable threshold levels, the quantity of discharged sediment, and the turbulent diffusivity in the Clarion Clipperton Fracture Zone.

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Section: Discussionmentioning

confidence: 99%

Extent of impact of deep-sea nodule mining midwater plumes is influenced by sediment loading, turbulence and thresholds

Muñoz-Royo

Peacock

Alford

et al. 2021

Commun Earth Environ

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“…These were higher than velocities inferred from laboratory measurements available at that time. This was attributed to higher particle interactions in situ or to the fact that the attenuation signal from the finest particles remained unresolved by the instrumentation [Lavelle et al, 1982;Ozturgut and Lavelle, 19815]. Later, an attempt was made to include some further aspects affecting the transport, such as velocity shear, sediment classes characterir.…”

mentioning

confidence: 99%

Numerical modeling of suspended sediment due to deep‐sea mining

Jankowski¹,

Malcherek²,

Zielke³

1996

J. Geophys. Res.

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A numerical model was developed in order to estimate the residence time of a sediment plume generated by potential deep‐sea mining activities, with special attention to discharges in the bottom boundary layer. The site of the Disturbance and Recolonization Experiment (DISCOL) in the Peru Basin in the southeast Pacific Ocean was chosen as a case study. The model includes the actual bathymetry, as well as the characteristic flow patterns of this region. Various aspects affecting the transport and sedimentation of the plume, such as stratification, flocculation in a sediment‐laden water column, and the hydrodynamics are discussed in conjunction with field data and studied with the overall aim of providing a reliable risk assessment of deep‐sea mining environmental impacts.

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“…Our monitoring array has provided an unprecedented insight into the spatial and temporal dispersion of anthropogenic sediment plumes in the abyssal ocean. Compared to impact experiments that were carried out in the past (e.g., Lavelle et al, 1982;Peukert et al, 2018;Spearman et al, 2020;Baeye et al, 2022), we placed many more sensors close to each other at welldefined locations in a large spatial array around the disturbance area. We were able to clearly detect the dispersion of the generated plume up to at least 300 m from the disturbance site.…”

Section: Discussionmentioning

confidence: 99%

“…To date, several plume dispersion studies have been performed during seafloor impact experiments (e.g., Jones et al, 2017;Gausepohl et al, 2020 and references therein), some of these in areas which are licensed for mineral exploration. These studies focused on the resettling of sediment, as inferred from sediment trap data or from seafloor imagery (Barnett and Suzuki, 1997;Yamazaki et al, 1997;Peukert et al, 2018;Gausepohl et al, 2020), as well as on the monitoring of the suspended sediment plumes (e.g., Lavelle et al, 1982;Brockett and Richards, 1994). Based on observations of sediment plume dispersion and plume settlement, model predictions have previously been made (e.g., Nakata et al, 1997;Jankowski ;Rolinski et al, 2001;Zielke, 2001).…”

Section: Introductionmentioning

confidence: 99%

Monitoring of Anthropogenic Sediment Plumes in the Clarion-Clipperton Zone, NE Equatorial Pacific Ocean

et al. 2022

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The abyssal seafloor in the Clarion-Clipperton Zone (CCZ) in the NE Pacific hosts the largest abundance of polymetallic nodules in the deep sea and is being targeted as an area for potential deep-sea mining. During nodule mining, seafloor sediment will be brought into suspension by mining equipment, resulting in the formation of sediment plumes, which will affect benthic and pelagic life not naturally adapted to any major sediment transport and deposition events. To improve our understanding of sediment plume dispersion and to support the development of plume dispersion models in this specific deep-sea area, we conducted a small-scale, 12-hour disturbance experiment in the German exploration contract area in the CCZ using a chain dredge. Sediment plume dispersion and deposition was monitored using an array of optical and acoustic turbidity sensors and current meters placed on platforms on the seafloor, and by visual inspection of the seafloor before and after dredge deployment. We found that seafloor imagery could be used to qualitatively visualise the redeposited sediment up to a distance of 100 m from the source, and that sensors recording optical and acoustic backscatter are sensitive and adequate tools to monitor the horizontal and vertical dispersion of the generated sediment plume. Optical backscatter signals could be converted into absolute mass concentration of suspended sediment to provide quantitative data on sediment dispersion. Vertical profiles of acoustic backscatter recorded by current profilers provided qualitative insight into the vertical extent of the sediment plume. Our monitoring setup proved to be very useful for the monitoring of this small-scale experiment and can be seen as an exemplary strategy for monitoring studies of future, upscaled mining trials. We recommend that such larger trials include the use of AUVs for repeated seafloor imaging and water column plume mapping (optical and acoustical), as well as the use of in-situ particle size sensors and/or particle cameras to better constrain the effect of suspended particle aggregation on optical and acoustic backscatter signals.

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Discharge and surface plume measurements during manganese nodule mining tests in the north equatorial pacific

Cited by 11 publications

References 5 publications

Extent of impact of deep-sea nodule mining midwater plumes is influenced by sediment loading, turbulence and thresholds

Extent of impact of deep-sea nodule mining midwater plumes is influenced by sediment loading, turbulence and thresholds

Numerical modeling of suspended sediment due to deep‐sea mining

Monitoring of Anthropogenic Sediment Plumes in the Clarion-Clipperton Zone, NE Equatorial Pacific Ocean

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