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About this book

This volume discusses environmental issues associated with deep-sea mining, with an emphasis on potential impacts, their consequences and the policy perspectives. The book describes the methods and technologies to assess, monitor and mitigate mining impacts on marine environments, and also suggests various approaches for environmental management when conducting deep-sea mining. The volume brings together information and data for researchers, contractors, mining companies, regulators, and NGOs working in the field of deep-sea mining.

Section 1 highlights the various environmental issues and discusses methods and approaches that can help in developing environmentally sustainable deep-sea mining.

Section 2 details the results and outcomes of studies related to impact assessment of deep-sea mining, and proposes methods for monitoring.

Section 3 discusses the need and means for developing data standards and their application to deep-sea mining.

Section 4 discusses the policies, approaches, and practices related to deep-sea mining, suggests formats for developing environmental impact statements (EIS) and environmental management plans (EMP), and describes national and international regulations for environmental management.

Section 5 concludes the text by putting deep-sea economic activities into an environmental context and conducting techno-economic analyses of deep-sea mining and processing.

Table of Contents


Environmental Issues


Deep-Sea Mining and the Environment: An Introduction

Seafloor minerals, many of which occur in the deep ocean in international waters, have attracted significant attention due to the discovery of deposits with high metal grades and large volumes, in addition to the growth in global demand for strategic metals such as copper, nickel, cobalt, and rare earths. Furthermore, much of the world is recognizing the need to transition to a clean energy, low-carbon economy, and to do so requires metals used in clean energy infrastructure and technologies, metals such as manganese, nickel, copper, and cobalt (World Bank 2017), the same metals found in, for example, polymetallic nodule deposits. This has led to several entities obtaining exploration contracts for areas of the seafloor governed under international regulations and developing technologies for their extraction. At the same time, environmental groups have raised concerns over the possible environmental impacts of deep-sea mining on seafloor and deep-sea ecosystems. This chapter provides an overview of the general environmental issues and concerns being raised in relation to deep-sea mining, introduces some of the mechanisms being put in place to ensure the effective protection of the marine environment, and raises pertinent questions that are being or will need to be addressed as the deep-sea minerals industry moves forward into reality.
Rahul Sharma, Samantha Smith

Environmental Issues of Deep-Sea Mining: A Law of the Sea Perspective

Addressing the environmental issues raised by deep-sea mining may provide an example for the international community on how to implement correctly the unqualified requirement in the United Nations Convention on the Law of the Sea (LOSC) that “States have the obligation to protect and preserve the marine environment”. This chapter offers an overview of how this could work.
Philomène A. Verlaan

Environmental Impacts of Nodule, Crust and Sulphide Mining: An Overview

The new industry of deep-sea mining (DSM) potentially offers abundant supplies of several metals from the deep ocean, but the ores will need to be recovered from pristine environments in which the ecosystems are often poorly known. Information that is available for some of these environments suggests that organisms may struggle to recover from the impacts of DSM, whilst in other areas the impacts may be somewhat less.
Deep-sea mining is focussed on three distinct resources – manganese nodules (also known as polymetallic nodules), cobalt crusts and seafloor massive sulphides (SMS) (sometimes called polymetallic sulphides). These occur in different seafloor settings, each hosting very different ecosystems and each with its own set of environmental issues.
Manganese nodules occur in the deep basins of the ocean where lack of sediment supply results in very slow sediment accumulation – rates that can be as low as 1 mm per thousand years – thus allowing nodules to form from slow precipitation of metals. Interest in mining manganese nodules is focussed mainly on the Clarion Clipperton Zone in the eastern equatorial Pacific and Central Indian Basin in the Indian Ocean. Here the seabed faunas are sparsely distributed but are very varied in composition. Many different species live in the upper few centimetres of the sediment or attached to the nodules. The mining process will disrupt this surface sediment layer and remove the nodules. Experiments have shown that species are very slow to return to the disrupted areas. Combined with the large areas that will need to be mined for manganese nodules, this gives rise to potentially a high environmental and ecological impact.
Cobalt crusts occur as layers up to 26 cm thick coating the rocky tops and upper flanks of seamounts, with the most promising deposits occurring between 800 and 2500 m water depth. The absence of sedimentation due to currents in these areas allows the slow growth of the crust via the precipitation of minerals from seawater. Seamount faunas are not well studied but they include a large number of species, many of which are slow-growing, long-lived and slow to reproduce. This makes it difficult for the ecosystem to recover from disruption. Large areas will need to be mined because the ore occurs in a very thin layer and whole seamounts may be affected.
The third resource – seafloor massive sulphides – differs from the previous two, being formed from precipitation of metals from hydrothermal fluids at oceanic plate boundaries. This process creates three-dimensional ore bodies extending metres into the seabed which are similar to some ore bodies that occur on land. Ecosystems comprising specialist organisms that can tolerate and make use of the harsh biochemical conditions are often found at active hydrothermal vents. These vent sites are probably too hot to ever be mined, so ore bodies are being sought some distance away from the active ridge axis in areas where venting is weaker or has stopped. The species occurring ‘off axis’ are more akin to those from the surrounding rocky slopes and possibly on the continental slopes in the same ocean basin. The species may occur over wide areas, and the impact of localised mining may be relatively small.
In all types of deep-sea mining, the generation of plumes of sediment-laden water, both by the mining process and the transport of ores to a support ship, will have an impact on benthic and mid-water ecosystems away from the mining site. If uncontrolled, such impacts could be comparable to or of greater scale to impacts in the mined areas.
Philip P. E. Weaver, David Billett

Towards an Ecosystem Approach to Environmental Impact Assessment for Deep-Sea Mining

There is growing recognition that a clean energy, low carbon future will require additional metals to be inserted into the world economy. This has led to increased interest in obtaining these metals from the seafloor of the deep ocean, with many proponents of the seafloor mineral industry claiming environmental and social advantages such as minimal waste, no disruption of indigenous populations, no need for deforestation including large areas of rainforest, and multi-metal and/or high-grade deposits. With interest in mining the deep seabed on the rise, an increasing number of exploration licences and contracts granted, and one mining project expected to be soon ready to commence operations, the deep seabed mineral industry is emerging, bringing with it a recognised need for thoughtful environmental assessment and management. This chapter examines the current state of knowledge of the services provided by ecosystems associated with deep-sea mineral deposits and how this knowledge can support the future inclusion of ecosystem services in environmental impact assessments (EIAs) for individual mining operations and in the regional-scale planning of resource extraction and conservation measures.
Faced with an incomplete understanding of deep-sea environments and the management strategies that could be deployed to minimise ecological losses from mining operations, scientists have expressed concern about the potential for related species extinctions, changes in ecosystem structure and function, and a loss of deep-sea ecosystem services (McGeoch et al. Diversity and Distributions, 16(1), 95–108, 2010; Van Dover Marine Environmental Research, 102, 59–72, 2014; Van Dover et al. Nature Geoscience, 10(7), 464–465, 2017; Folkersen et al. Marine Policy, 94, 71–80, 2018). The environmental costs of extracting deep-sea mineral resources have been the subject of an increasing number of studies, yet remain difficult to quantify (Thurber et al. Biogeosciences, 10(11), 18193–18240, 2014; Jobstvogt et al. Ecological Economics, 97, 10–19, 2014; Folkersen et al. Marine Policy, 94, 71–80, 2018). Regulators of future deep-sea mining activities have been developing rules, regulations, and guidelines aimed at the responsible use of seabed mineral resources and that conservation goals are met. Key players in the seabed mineral industry have committed to a precautionary and ecosystem-based approach to environmental management that aims to mitigate the potential impacts of mining. Part of this approach includes employing best environmental practice and tools used in environmental management, including robust EIAs and adaptive management.
Kate J. Thornborough, S. Kim Juniper, Samantha Smith, Lynn-Wei Wong

Technologies for Safe and Sustainable Mining of Deep-Seabed Minerals

Safety and sustainability are both critical for the sake of profitability in deep-seabed mining. Environmental impacts and potential harms to ecosystems would be caused basically by benthic intervention and materials transportation. A commercial mining has to be based on minimizing of the environmental impacts. For safe and sustainable mining, the entire mining system should be designed with the objectives of the production efficiency of minerals and the feasibility of treatment of by-products (seawater, sediment) and operated in an integrated and smart fashion. Utilization of techniques of simulation-based design (SBD) and multidisciplinary design optimization (MDO) and also implementation of underwater robot technology are required to ensure operability and sustainability as well as to reduce development risks as well.
Sup Hong, Hyung-Woo Kim, Taekyung Yeu, Jong-Su Choi, Tae Hee Lee, Jong-Kap Lee

Environmental Impact Assessment


Assessment of Deep-Sea Faunal Communities-Indicators of Environmental Impact

Our assessment of deep-sea faunal communities is based on the results of a comprehensive UNESCO/IOC baseline study of the megafaunal assemblages of the metallic nodule ecosystem of five areas within the Clarion Clipperton Zone (CCZ) of the eastern Pacific Ocean. This study serves as benchmark to interpret the structure of megafaunal populations associated with benthic biotopes in areas targeted for mining. It identifies on a large scale the variability of nodule and sediment facies and their associations with specific megafaunal communities. An appropriate set of management tools and options have been developed, in particular indicators of sensitivity to environmental changes anthropogenically or naturally induced. The general characteristics of the nodule ecosystem in the CCZ and its sensitivity to deep-sea mining are discussed from the surface to the seabed in relation to recent research on the description of water masses and dynamics and an assessment of their vulnerability. A tridimensional multiparametric rapid environmental assessment (REA) has been applied on one pilot site of the French contract area using GIS zoning, ecohydrodynamics, and sensitivity indexes.
Virginie Tilot

Long-Term Monitoring of Environmental Conditions of Benthic Impact Experiment

The Japan Deep-Sea Impact Experiment (JET) is an in situ experiment aimed at evaluating the environmental impacts and recovery process arising from associated manganese nodule mining. The experiment was initiated in 1994 and ended in 1996. However, owing to the short monitoring period, it was not possible to gain adequate understanding of the recovery process. Subsequently, the Deep Ocean Resources Development Co., Ltd., revisited the site 1718 years later and surveyed the environmental conditions (long-term monitoring survey). This survey found that the environmental impacts that were recognizable immediately after and 1 year after benthic disturbance were not visible after 1718 years. This chapter presents the results of the long-term monitoring survey and discusses future plans of environmental impact evaluations.
Tomohiko Fukushima, Akira Tsune

Metal Mobility from Hydrothermal Sulfides into Seawater During Deep Seafloor Mining Operations

Seafloor hydrothermal sulfides, which are expected to be a future resource for metals, could be a potential source for metal contamination in the seawater around mining sites. In this chapter, we illustrate the potential for metal leaching of both non-oxidized (non-exposed to atmosphere; before and during exploitation) and oxidized (exposed to atmosphere; after lifting and recovery) hydrothermal sulfides to seawater under different temperatures and redox conditions. One of the crucial findings was that metal dissolution behaviors differed significantly according to the specific areas and/or the initial oxidation states of the sulfide surfaces. Once the non-oxidized sulfide chips were ground to particulates and mixed with seawater, Zn and Pb were preferentially released even though these metals were included as minor components of the sulfides. For Zn, the dissolution rate increased under the oxic and higher temperature (20 °C) conditions when compared to the anoxic and lower temperature (5 °C) conditions, but the absolute rate was relatively moderate. These findings suggest that instantaneous metal release from sulfides into seawater will not occur before or during the crushing and lifting processes of seafloor mining. In contrast to the non-oxidized sulfides, the oxidized sulfides rapidly released large amounts of various metals and metalloids (e.g., Mn, Fe, Zn, Cu, As, Sb, and Pb) into seawater. The different metal dissolution behaviors between the non-oxidized and oxidized hydrothermal sulfides suggest the importance of the implementation of appropriate environmental measures to prevent leakage of the lifted sulfides to the marine surface.
Shigeshi Fuchida, Jun-ichiro Ishibashi, Tatsuo Nozaki, Yoshitaka Matsushita, Masanobu Kawachi, Hiroshi Koshikawa

Mining in Hydrothermal Vent Fields: Predicting and Minimizing Impacts on Ecosystems with the Use of a Mathematical Modeling Framework

Accelerated demand for exploration of minerals and development of mining technologies over the past decade could lead to commercial mining of the deep seafloor in the near future. The campaign for conservation of biological diversity claims that there will be impacts of seabed mining to the deep-sea community and suggests a precautionary approach. In this chapter, we summarize the basic characteristics of communities in hydrothermal vent fields and describe the potential impact of resource mining as well as some previous observations on the effect of natural disturbances. We then introduce a model-based approach to determine the resilience of vent communities, thereby predicting if the communities will be vulnerable or robust to disturbances. Resilience of ecological systems is assessed by measuring the time required to recover to the original state prior to being disturbed. A mathematical model capable of predicting resilience would represent an important contribution to the management of these unique ecosystems. However, compared to most terrestrial and shallow water ecosystems, information regarding hydrothermal vent ecosystems, which are typically found at depths of over 1000 m, is limited. We thus focused on connectivity of vent communities through larval dispersal as a key factor for resilience. We will show how our framework can be used as a practical tool to characterize, understand, or predict resilience. The framework presented here can help assess ecological impacts and develop mitigation strategies associated with deep-sea resource mining. We also discuss what will need to be developed further to better achieve these objectives.
Kenta Suzuki, Katsuhiko Yoshida

Ecotoxicological Bioassay Using Marine Algae for Deep-Sea Mining

A new bioassay method using delayed fluorescence (DF) intensity in marine cyanobacterium has been developed. This method offers several advantages for marine environmental risk assessment in deep-sea mining areas: DF-based bioassay uses smaller amounts of a test substance or wastewater and takes less time and space than the standard bioassay method. We selected the marine cyanobacterium Cyanobium sp. (NIES-981) as our test algal species and demonstrated that use of this species was valid in standard growth inhibition testing based on OECD guideline criteria. Standard inhibition tests and shorter testing using DF were performed on NIES-981 by using five chemicals (3,5-DCP, simazine, diflufenican, K2Cr2O7, and CuSO4), and their EC50 and low-toxic-effect values (EC10, EC5, and NOEC) were determined from dose-response curves. On the basis of comparisons of the two dose-response curves and the EC50 values, we concluded that DF intensity was useful as an endpoint for rapid estimation of EC50 in NIES-981. In addition, a delayed fluorescence-based bioassay using Cyanobium sp. NIES-981 was used to evaluate the toxicity of core samples obtained from drill holes at the Izena Hole, Middle Okinawa Trough, East China Sea. The results revealed that unexpected leakage of recovered minerals and mining wastewater from the mining plant could result in heavy metal contamination of the surface water. Moreover, on the basis of the results of microplate-based assay using various marine algae, we suggest using eukaryotic marine algae such as Emiliania huxleyi NIES-1310, Micromonas pusilla NIES-1411, and Bathycoccus prasinos NIES-2670 in addition to Cyanobium sp. NIES-981 for management of seawater quality at deep-sea mining sites because sensitivity to lead in eukaryotic marine algae are more sensitive than cyanobacteria.
Takahiro Yamagishi, Shuhei Ota, Haruyo Yamaguchi, Hiroshi Koshikawa, Norihisa Tatarazako, Hiroshi Yamamoto, Masanobu Kawachi

Environmental Data Standardization and Application


New Techniques for Standardization of Environmental Impact Assessment

The exploitation of deep-sea mineral resources has not yet begun. In order to realize it in the future, various issues need to be addressed. One such issue is establishing an appropriate environmental impact assessment (EIA) technique and a supporting environmental research method. At present, knowledge on the deep-sea environment is quite poor, and existing environmental research methods rely on various methods used in ocean science. However, the goals of oceanography do not always align with those for EIA. Furthermore, the purposes of EIA and scientific research are different. Considering economic performance and technical convenience, scientific research methods are not necessarily suitable for EIA. In this context, this paper introduces three new technologies of turbulence measurement, niche modeling, and genetic connectivity survey method and suggests approaches for their standardization for the purpose of EIA.
Yasuo Furushima, Takehisa Yamakita, Tetsuya Miwa, Dhugal Lindsay, Tomohiko Fukushima, Yoshihisa Shirayama

Environmental Factors for Design and Operation of Deep-Sea Mining System: Based on Case Studies

This chapter brings together environmental factors that are expected to influence the design and operation of deep-sea mining system for polymetallic nodules. The study analyzes possible effects of various environmental factors from nodule-bearing areas in the Central Indian Ocean Basin (CIOB) and compares it with available data from the Pacific Ocean. Similar applications can be envisaged for different mineral deposits in other ocean basins as well.
Rahul Sharma

Environmental Management


Environmental Policy for Deep Seabed Mining

This chapter examines the issue of developing deep-sea mining (DSM) while managing the impact upon deep seabed environmental assets. It reviews pertinent background information relating to DSM and the environment; develops a suite of potential policy instruments, including both direct and incentive-based regulation; develops additional incentive-based policy instruments, largely drawn from terrestrial conservation, for potential consideration; briefly touches upon technology and innovation to address mitigation of adverse environmental impacts from DSM; and then provides a concluding discussion.
Michael W. Lodge, Kathleen Segerson, Dale Squires

Ecosystem Approach for the Management of Deep-Sea Mining Activities

Within a regulatory context, an environmental impact assessment is more than an assessment of impacts of a given project’s footprint. It involves a review of the impacts that could occur in addition to the potential impacts from catastrophic events and the need for emergency responses. In most cases, there are a number of regulatory requirements that fall within a broad range of jurisdictions and competent authorities. Environmental impact assessments are done primarily to identify ecosystem and socio-economic issues that become the basis for management measures to prevent and mitigate the impacts as conditions for project approvals.
This chapter discusses the need to reconcile the scale of ecosystem vulnerabilities with the impacts generated by deep-sea mining activities as the basis for an ecosystem approach. It introduces the use of international risk management standards and techniques already in use in the industry to bridge the assessment of these vulnerabilities with the regulatory requirements of this industry. It discusses the need for an assessment of effectiveness of the controls, measures and procedures in preventing and mitigating ecosystem impacts.
Roland Cormier

Improving Environmental Management Practices in Deep-Sea Mining

As the business of deep-sea mining develops, greater attention is being paid to the ways in which the impacts from mining on the environment might be minimised and controlled. The management of environmental impacts is highly complex encompassing a wide variety of topics including physical oceanography, sediment characteristics, particle sinking velocities, particle aggregation, sediment geochemistry, toxic discharges, chemical contamination, biological studies from microbes to mammals and from the sea surface to the subseabed, studies of biodiversity, genetic connectivity, ecosystem functioning, the value of ecosystem services, hydrodynamic plume modelling and noise and light hazards. Owing to the history of how contractors in deep-sea mining have developed, there are a wide variety of approaches to environmental management. This chapter seeks to assist contractors in achieving a more consistent approach by making some key recommendations and highlighting some outstanding issues. It covers why environmental baseline studies are necessary and how various levels of environmental assessment will help contractors achieve a suitable standard when submitting Environmental Impact Assessments. In particular it highlights the use of the ‘mitigation hierarchy’ as a suitable way to consider environmental management issues. Apart from detailing ways in which environmental impacts might be minimised and avoided altogether, at the local and regional scales, the chapter calls for greater consideration of ways to assist ecosystems to recover more quickly through enhancing natural ecosystem processes. The restoration of marine ecosystems, as occurs after a mine has been closed on land, should be included in environmental planning but requires experimental research to be undertaken during the exploration phase and before an Environmental Impact Statement is submitted to gain an environmental and social licence to exploit deep-sea minerals.
D. S. M. Billett, D. O. B. Jones, P. P. E. Weaver

The Development of Environmental Impact Assessments for Deep-Sea Mining

The chapter provides an account of general Environmental Impact Assessment (EIA) processes and applications, and their role in the developing exploitation of deep-sea mineral resources. It includes aspects such as definitions, the position of EIA as part of a larger process, the structure and content of an EIS and the role of risk assessment in the EIA and considers some of the key elements specific to deep-sea mining that need to be addressed as potential mining progresses from exploration to future exploitation. Elements identified by the ISA, and examples from national assessments, are also reviewed briefly to determine what will be required in future.
Malcolm R. Clark

Protection of the Marine Environment: The International and National Regulation of Deep Seabed Mining Activities

This chapter provides an overview of the international and national regulatory framework pertaining to deep seabed mining activities. It begins by discussing the UN Convention on the Law of the Sea, the backdrop for all marine activities – be they national or international – and examines the obligations of states to protect the marine environment from the harmful effects arising from deep seabed mining. Next, the chapter examines the international regime for deep seabed mining (i.e. “activities in the Area”), explaining the “common heritage of mankind” status of the Area (i.e. the international seabed); the functions of the International Seabed Authority (ISA), the international organization established to govern deep seabed mining in the Area; and the concept of state sponsorship of non-state entities (i.e. private actors) for deep seabed mining in the Area. The chapter follows with a discussion of the development of national legislation to regulate deep seabed mining, examining efforts in the Pacific region where many prospective deep-sea mining sites are located. This includes a look at the legislative regimes of several Pacific Island nations, namely, Papua New Guinea, Tonga and the Cook Islands, for whom deep seabed mining may soon become a reality – as well as New Zealand and Japan, countries with comparatively developed rule of law and legislative regimes that have undertaken or considered deep seabed mining in their national waters. Overall, the chapter critically describes and evaluates the current regulatory status in the international and national seabed areas and highlights some salient gaps that require urgent attention in order to ensure marine environmental protection and mitigate impacts on humans.
Pradeep Singh, Julie Hunter

Economic Considerations


Deep-Sea Natural Capital: Putting Deep-Sea Economic Activities into an Environmental Context

The natural capital of the vast deep ocean is significant yet not well quantified. The ecosystem services provided by the deep sea provide a wide range of benefits to humanity. Proposed deep-sea economic activities such as fishing, deep-sea mining and bioprospecting therefore need to be assessed in this context. In addition to quantifying the economic benefits and costs of such activities on their own, their potential impact on the deep-sea natural capital also needs to be considered.
This article describes such a natural capital approach, identifies relevant ecosystem services and looks at how a range of proposed commercial activities could be assessed in this context. It suggests a methodology for such analysis and suggests an approach to a sustainable blue deep-sea economy that is consistent with environmental precaution. It will close with suggestions of how potential risks can best be handled.
The article aims to show that modern environmental economics based on natural capital can provide a useful framework for deciding future deep-sea efforts.
Torsten Thiele

Review of Mining Rates, Environmental Impacts, Metal Values, and Investments for Polymetallic Nodule Mining

This chapter reviews different mining rates for polymetallic nodules and evaluates the ensuing environmental impacts as well as metal production with respect to land reserves, metal prices, and projected investments. It is expected that these can be applied for different mineral deposits in other ocean basins as well.
Rahul Sharma, Farida Mustafina, Georgy Cherkashov

Techno-economic Perspective on Processing of Polymetallic Ocean Nodules

This chapter looks at the techno-economic feasibility of processing of polymetallic nodules obtained from Pacific as well as Indian Ocean with an emphasis on cobalt market. Numerous processing routes have been developed for recovery of three (Cu + Ni + Co) as well as four (Cu + Ni + Co + Mn) metals. Some of the processes tested on scales varying from tens to a few hundreds of kilograms per batch indicate that there are no major gaps in the processing technologies. With the passage of time, recovery of molybdenum and rare earth elements (Mo and REE) from this resource has also gained importance. Various feasibility studies for extraction of metals from polymetallic nodules are presented in this chapter with respect to operating and capital investments for a 1.5/3.0 million tonne plant. It appears that enhanced requirement of cobalt and nickel mainly for the battery industry may drive the deep-sea mining in the future. The study concludes that it would be advisable to target 4+ metal recoveries (including Mo, REE, etc.) and design a flexible flow sheet for optimal product mix to get maximum value addition.
Navin Mittal, Shashi Anand


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