Deep-sea mining on the Rio Grande Rise (Southwestern Atlantic): A review on environmental baseline, ecosystem services and potential impacts

Montserrat, F.; Guilhon, Maila; Corrêa, Paulo Vinicius Ferraz; Bergo, Natascha Menezes; Signori, Camila Negrão; Tura, Pedro Marone; Maly, Mascimiliano; Moura, Denise Silva de; Jovane, Luigi; Pellizari, Vivian H.; Sumida, Paulo Yukio Gomes; Brandini, Frederico Pereira; Turra, Alexander

doi:10.1016/j.dsr.2018.12.007

Cited by 46 publications

(55 citation statements)

References 182 publications

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“…An NW-SE trending 10 to 20 km-wide and 1000 m-deep valley cuts through the center of the entire RGR, which may correspond to an accommodation zone resulting from extension in the region [15]. The central valley provides an extremely steep slope up to the rim of RGR plateau, which is an area where Fe-Mn crusts are likely to form due to lower sedimentation on the slope as well as exposed rock surfaces [14]. Although the formation of RGR is not fully understood, some agreement exists among studies that RGR and Walvis Ridge in the southeast Atlantic formed together as a single ridge on the MAR during the Coniacian/Santonian (85 Myr; [16]).…”

Section: Study Areamentioning

confidence: 99%

“…Currents around RGR are strong (up to 50 cm•s −1 ) but variable due to tidal effects [21]. The horizontal current velocity at the seabed is enhanced along the shallower areas of the RGR main plateau [14], which may promote Fe-Mn crust erosion.…”

Section: Study Areamentioning

confidence: 99%

“…Knowledge about the environment of RGR is scarce and even baseline information needed for potential future mining activities is not available [14], especially concerning the extent of mineral deposits, the main sediment and rock types, small-scale morphology, and ecosystems. Here, we explore mineralogical, geochemical, and isotopic characteristics of Fe-Mn crusts from the summit area of RGR.…”

Section: Introductionmentioning

confidence: 99%

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Genesis and Evolution of Ferromanganese Crusts from the Summit of Rio Grande Rise, Southwest Atlantic Ocean

et al. 2020

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The Rio Grande Rise (RGR) is a large elevation in the Atlantic Ocean and known to host potential mineral resources of ferromanganese crusts (Fe–Mn), but no investigation into their general characteristics have been made in detail. Here, we investigate the chemical and mineralogical composition, growth rates and ages of initiation, and phosphatization of relatively shallow-water (650–825 m) Fe–Mn crusts dredged from the summit of RGR by using computed tomography, X-ray diffraction, 87Sr/86Sr ratios, U–Th isotopes, and various analytical techniques to determine their chemical composition. Fe–Mn crusts from RGR have two distinct generations. The older one has an estimated age of initiation around 48–55 Ma and was extensively affected by post-depositional processes under suboxic conditions resulting in phosphatization during the Miocene (from 20 to 6.8 Ma). As a result, the older generation shows characteristics of diagenetic Fe–Mn deposits, such as low Fe/Mn ratios (mean 0.52), high Mn, Ni, and Li contents and the presence of a 10 Å phyllomanganate, combined with the highest P content among crusts (up to 7.7 wt %). The younger generation is typical of hydrogenetic crusts formed under oxic conditions, with a mean Fe/Mn ratio of 0.75 and mean Co content of 0.66 wt %, and has the highest mean contents of Bi, Nb, Ni, Te, Rh, Ru, and Pt among crusts formed elsewhere. The regeneration of nutrients from local biological productivity in the water column is the main source of metals to crusts, providing mainly metals that regenerate rapidly in the water column and are made available at relatively shallow water depths (Ni, As, V, and Cd), at the expense of metals of slower regeneration (Si and Cu). Additionally, important contributions of nutrients may derive from various water masses, especially the South Atlantic Mode Water and Antarctic Intermediate Water (AAIW). Bulk Fe–Mn crusts from the summit of RGR plateau are generally depleted in metals considered of greatest economic interest in crusts like Co, REE, Mo, Te, and Zr, but are the most enriched in the critical metals Ni and Li compared to other crusts. Further investigations are warranted on Fe–Mn crusts from deeper-water depths along the RGR plateau and surrounding areas, which would less likely be affected by phosphatization.

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Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Genesis and Evolution of Ferromanganese Crusts from the Summit of Rio Grande Rise, Southwest Atlantic Ocean

et al. 2020

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“…To date, there are very few studies on the pelagic communities in deep‐sea seamounts. Moreover, those focused primarily on phytoplankton and zooplankton (Cordeiro, Brandini, Rosa, & Sassi, 2013; Dower & Mackas, 1996; Genin, 2004; Montserrat et al, 2019; Sampaio de Souza, Guimarães da Luz, Macedo, Montes, & Mafalda, 2013; Sonnekus, Bornman, & Campbell, 2017). Further, virioplankton have received the least attention of all members of this microbial community.…”

Section: Introductionmentioning

confidence: 99%

Virioplankton distribution in the tropical western Pacific Ocean in the vicinity of a seamount

Zhao

Zheng

et al. 2020

MicrobiologyOpen

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The shallow Caroline Seamount is located in the tropical western Pacific Ocean. Its summit is 57 m below the surface and penetrates the euphotic zone. Therefore, it is ideal for the study of the influence of seamount on plankton distribution. Here, virioplankton abundance and distribution were investigated by flow cytometry (FCM) in the Caroline Seamount in August and September 2017. The total abundance of virus‐like particles (VLP) was in the range of 0.64 × 106–18.77 × 106 particles/ml and the average was 5.37 ± 3.75 × 106 particles/ml. Three to four distinct viral subclusters with similar side scatter but different green fluorescence intensities were identified. Above the deep chlorophyll maximum (DCM), two medium fluorescence virus (MFV) subclusters were discriminated. Between the DCM and the deeper layers, only one MFV subcluster was resolved. In general, low fluorescence viruses (LFV) comprised the most abundant subclusters. In the 75–150 m water column, however, the MFV abundance was higher than the LFV abundance. High fluorescence viruses (HFV) constituted the least abundant subcluster throughout the entire water column. Virioplankton abundance was significantly enhanced at the seamount stations. Environmental factors including water temperature and nitrate concentration were the most correlated with the variation in virioplankton abundance at the seamount stations. Interactions between shallow seamounts and local currents can support large virus standing stocks, causing a so‐called indirect “seamount effect” on the virioplankton.

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“…The western Rio Grande Rise (RGR), where this research took place, is an extensive oceanic rise (∼150,000 km 2 ) in the South Atlantic Ocean, located ∼1,000 km to the east of the Brazil and Argentine basins (Cavalcanti et al, 2015). The RGR has gained special attention from scientists and governments worldwide due to its marine mineral deposits and, as yet, the controversial origin of the rise itself (Montserrat et al, 2019). In 2015, the International Seabed Authority (ISA) and the state-owned Companhia de Pesquisa de Recursos Minerais (CPRM) of Brazil signed a 15-year contract for exploration of Co-rich ferromanganese crusts in the RGR, accentuating the need for baseline environmental studies in the area.…”

Section: Introductionmentioning

confidence: 99%

Multidisciplinary Scientific Cruise to the Rio Grande Rise

et al. 2019

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Deep-sea mining on the Rio Grande Rise (Southwestern Atlantic): A review on environmental baseline, ecosystem services and potential impacts

Cited by 46 publications

References 182 publications

Genesis and Evolution of Ferromanganese Crusts from the Summit of Rio Grande Rise, Southwest Atlantic Ocean

Genesis and Evolution of Ferromanganese Crusts from the Summit of Rio Grande Rise, Southwest Atlantic Ocean

Virioplankton distribution in the tropical western Pacific Ocean in the vicinity of a seamount

Multidisciplinary Scientific Cruise to the Rio Grande Rise

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