Environmental issues of deep sea mining impacts, consequences and policy perspectives

Rahul Sharma
Editor

Environmental
Issues of
Deep-Sea Mining
Impacts, Consequences
and Policy Perspectives


Environmental Issues of Deep-Sea Mining


Rahul Sharma
Editor

Environmental Issues
of Deep-Sea Mining
Impacts, Consequences and Policy
Perspectives


Editor
Rahul Sharma
CSIR-National Institute of Oceanography
Dona Paula, Goa, India

ISBN 978-3-030-12695-7    ISBN 978-3-030-12696-4 (eBook)
/>© Springer Nature Switzerland AG 2019
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in published maps and institutional affiliations.
Cover Image: A schematic showing the processes involved in deep-sea mining for the three main types of
mineral deposits. (Left to Right: hydrothermal sulphides, polymetallic nodules, ferromanganese crusts - Not
to scale) (Adopted from: Kathryn A. Miller, Kirsten Thompson, Paul Johnston, David Santillo, 2018. An
Overview of Seabed Mining Including the Current State of Development, Environmental Impacts, and
Knowledge Gaps. Front. Mar. Sci., volume 4, />This Springer imprint is published by the registered company Springer Nature Switzerland AG
The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland


Below: Seabed photographs of benthic organisms associated with deep-sea
minerals in different oceans:

Image of the seafloor in the abyssal Pacific showing manganese nodules and large deep-water
prawn (Bathystylodactylus sp.). Image shows an area of seafloor approximately 50cm across.
(Credit: Image courtesy Dr Daniel Jones, National Oceanography Centre, Southampton)

Typical area of rocky seabed away from the ridge axis with the crinoid Anachalypsicrinus nefertiti
and some large sponges. Mid Atlantic Ridge, depth c. 2400m. (Credit: Image courtesy Dr Daniel
Jones, National Oceanography Centre, Southampton, UK. ECOMAR Project)

Abundant Chrysomallon squamiferum and Gigantopelta aegis, with Kiwa n. sp. “SWIR”,
Bathymodiolus marisindicus, and Mirocaris fortunata on platform of “Tiamat” vent chimney,
Southwest Indian Ridge, depth 2778m (Credit: Image courtesy NERC University of Southampton,
SWIR_2011-11-27_10-24-08_James Cook_JC67_2_ROV01)

v


Foreword

vii


Foreword

ix


Preface

Deep-sea mining is currently in a transitional phase between exploration and exploitation of deep-sea mineral deposits that are projected as alternative source of metals to
depleting land resources in future. On one hand, long-term prospecting and resource
evaluation has led to the identification of potential mining areas on the deep seafloor.
On the other, the development of mining and processing technology is gaining
momentum, with a few entities planning their sea trials in the near future. However,
the commencement of mining of deep-sea minerals on a commercial scale depends on
metal prices and their availability in the world market.
In view of the concerns over potential disturbances in the marine environment
due to various offshore and onshore activities, the world community is focusing its
attention to the environmental issues of deep-sea mining. This is more so because

many of the deep-sea minerals occur in the “Area”, that is, areas that lie in international waters beyond the national jurisdiction of any state. As the mining operations
could be expected to commence in the coming decades, pertinent questions that
need to be answered include what are the possible environmental impacts, who is
responsible for it, how do we regulate the activities in this area, what if the concerned party does not (or cannot) do anything about it, what are the mitigation
measures, and how do we restore or conserve the marine environment.
This book brings forth various issues with contributions from leading experts
under different themes such as the environmental issues of deep-sea mining, its
potential impacts, environmental data standardization and applications, environmental management, and economic considerations. The contributions from all the
authors are highly acknowledged with a hope that this book will serve as a comprehensive reference material for addressing various environmental issues of
deep-sea mining.
As deep-sea mining is an activity of the future, with increasing environmental
awareness, it is incumbent on all stakeholders, including the potential contractors,
the sponsoring states, the international regulating agencies, and the environmental
groups, to devise strategies for economically and environmentally sustainable
deep-­sea mining ventures to meet the future demand for metals in the world and
preserve the marine environment within acceptable limits.
xi


xii

Preface

It is important to realize that just as it is our responsibility to give a healthy
environment to the next generation, it is equally incumbent on us to ensure the
availability of adequate resources for their future.
Dona Paula, Goa, India 

Rahul Sharma

Acknowledgments

This book on Environmental issues of Deep-Sea Mining – Impacts, Consequences
and Policy Perspectives is a sequel to Deep-Sea Mining  – Resource Potential,
Technical and Environmental Considerations published by Springer in 2017. Both
the publications have been possible due to the confidence entrusted by the publishers in the topics addressed in these books. I acknowledge the support extended by
them in this endeavor, in particular Dr. Sherestha Saini, Mr. Aaron Schiller, and Ms.
Susan Westendorf from the Springer New York Office, as well as the staff of SPi
Global, particularly Ms. M. K. Chandhini and Ms. S. Kanimozhi for production of
the book.
All the authors of the chapters deserve a special mention for their outstanding
contributions, despite having multiple commitments, that has made this publication
possible. Each chapter is unique in its content, and the ideas presented give the book
a broad perspective. This shows the rich expertise that the authors have and their
willingness to share the same is highly appreciated.
The Foreword by Mr. Michael Lodge, Secretary General, International Seabed
Authority, Jamaica, gives a comprehensive overview of the issues related to the
subject of deep-sea mining and environment and sets the tone for this book. Also the
Foreword by Prof. M. Rajeevan, Secretary, Ministry of Earth Sciences (Government
of India), New Delhi, provides a way forward in the field of deep-sea mining and
environmental conservation. The encouragement and support received from Mr.
Lodge and Prof. Rajeevan are sincerely acknowledged.
This book is the result of a suggestion from Dr. T.  R. P.  Singh, Ex-General
Manager, Engineers India Limited, New Delhi, to bring together a large volume of
information on the subject in one place, including the experimental data, regulations, and management of deep-sea mining from an environmental perspective.
Discussions with officials of the Ministry of Earth Sciences, Government of India,
as well as the inputs of Prof. PK Sen, IIT Kharagpur, were very helpful during this
project and in writing my chapters.
CSIR-National Institute, Goa, where I have worked for almost 36 years, holds a

very special place in shaping my career and developing my understanding of the
subject that led me to take up the challenge of putting this book together.
xiii


xiv

Acknowledgments

Special thanks are due to my colleagues for their inputs as well as the directors of
the Institute for their support during the compilation of this book.
And finally, the members of my immediate as well as extended families have
been the source of constant encouragement through this endeavor, and their support
is highly appreciated.
May God bless us all.
Rahul Sharma
CSIR-National Institute of Oceanography
Dona Paula, Goa, India


Contents

Part I Environmental Issues
Deep-Sea Mining and the Environment: An Introduction ��������������������������    3
Rahul Sharma and Samantha Smith
Environmental Issues of Deep-Sea Mining: A Law
of the Sea Perspective��������������������������������������������������������������������������������������   23
Philomène A. Verlaan
Environmental Impacts of Nodule, Crust and Sulphide Mining:
An Overview ����������������������������������������������������������������������������������������������������   27

Philip P. E. Weaver and David Billett
Towards an Ecosystem Approach to Environmental Impact
Assessment for Deep-Sea Mining�������������������������������������������������������������������   63
Kate J. Thornborough, S. Kim Juniper, Samantha Smith,
and Lynn-Wei Wong
Technologies for Safe and Sustainable Mining of Deep-Seabed
Minerals������������������������������������������������������������������������������������������������������������   95
Sup Hong, Hyung-Woo Kim, Taekyung Yeu, Jong-Su Choi,
Tae Hee Lee, and Jong-Kap Lee
Part II Environmental Impact Assessment
Assessment of Deep-Sea Faunal Communities-Indicators
of Environmental Impact��������������������������������������������������������������������������������  147
Virginie Tilot
Long-Term Monitoring of Environmental Conditions of Benthic
Impact Experiment������������������������������������������������������������������������������������������  191
Tomohiko Fukushima and Akira Tsune

xv


xvi

Contents

Metal Mobility from Hydrothermal Sulfides into Seawater During
Deep Seafloor Mining Operations������������������������������������������������������������������  213
Shigeshi Fuchida, Jun-ichiro Ishibashi, Tatsuo Nozaki,
Yoshitaka Matsushita, Masanobu Kawachi, and Hiroshi Koshikawa
Mining in Hydrothermal Vent Fields: Predicting and Minimizing
Impacts on Ecosystems with the Use of a Mathematical

Modeling Framework��������������������������������������������������������������������������������������  231
Kenta Suzuki and Katsuhiko Yoshida
Ecotoxicological Bioassay Using Marine Algae for Deep-Sea Mining��������  255
Takahiro Yamagishi, Shuhei Ota, Haruyo Yamaguchi, Hiroshi Koshikawa,
Norihisa Tatarazako, Hiroshi Yamamoto, and Masanobu Kawachi
Part III Environmental Data Standardization and Application
New Techniques for Standardization of Environmental Impact
Assessment��������������������������������������������������������������������������������������������������������  275
Yasuo Furushima, Takehisa Yamakita, Tetsuya Miwa, Dhugal Lindsay,
Tomohiko Fukushima, and Yoshihisa Shirayama
Environmental Factors for Design and Operation of Deep-Sea
Mining System: Based on Case Studies ��������������������������������������������������������  315
Rahul Sharma
Part IV Environmental Management
Environmental Policy for Deep Seabed Mining��������������������������������������������  347
Michael W. Lodge, Kathleen Segerson, and Dale Squires
Ecosystem Approach for the Management of Deep-Sea Mining
Activities������������������������������������������������������������������������������������������������������������  381
Roland Cormier
Improving Environmental Management Practices in Deep-Sea
Mining ��������������������������������������������������������������������������������������������������������������  403
D. S. M. Billett, D. O. B. Jones, and P. P. E. Weaver
The Development of Environmental Impact Assessments
for Deep-Sea Mining����������������������������������������������������������������������������������������  447
Malcolm R. Clark
Protection of the Marine Environment: The International
and National Regulation of Deep Seabed Mining Activities������������������������  471
Pradeep Singh and Julie Hunter
Part V Economic Considerations
Deep-Sea Natural Capital: Putting Deep-­Sea Economic Activities

into an Environmental Context����������������������������������������������������������������������  507
Torsten Thiele


Contents

xvii

Review of Mining Rates, Environmental Impacts, Metal Values,
and Investments for Polymetallic Nodule Mining����������������������������������������  519
Rahul Sharma, Farida Mustafina, and Georgy Cherkashov
Techno-economic Perspective on Processing of Polymetallic Ocean
Nodules��������������������������������������������������������������������������������������������������������������  547
Navin Mittal and Shashi Anand
Index������������������������������������������������������������������������������������������������������������������  567


Part I

Environmental Issues


Deep-Sea Mining and the Environment:
An Introduction
Rahul Sharma and Samantha Smith

Abstract  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.
Keywords  Deep-sea mining · Environmental issues · Sustainable development

R. Sharma (*)
CSIR-National Institute of Oceanography, Dona Paula, Goa, India
S. Smith
Blue Globe Solutions, Toronto, ON, Canada
Nauru Ocean Resources Inc., Aiwo, Republic of Nauru
e-mail:
© Springer Nature Switzerland AG 2019
R. Sharma (ed.), Environmental Issues of Deep-Sea Mining,
/>
3


4

R. Sharma and S. Smith

1  Background
It is well known that any human interference with nature perturbs natural conditions. Seas and open oceans are often thought of by the general public as pristine

parts of the earth’s surface that have regularly symbolized relatively undisturbed,
well-balanced ecosystems that humankind would like to preserve eternally, especially after having seen the ill effects of anthropogenic activities on land. However,
the oceans, including the deep sea, are not entirely pristine with a number of activities already occurring such as shipping, waste disposal (including nuclear, plastics,
and mine tailings), fishing including bottom trawling, and others. Increasing demand
for resources in order to satisfy the growing requirements of humankind have also
pushed the boundaries of exploring and exploiting marine resources in the last few
decades, in shallow waters, and in the deep sea.
One such marine resource entails seafloor mineral deposits such as polymetallic
nodules, polymetallic/hydrothermal/seafloor massive sulfides and ferromanganese/
cobalt-rich crusts (Table 1). These deposits are considered alternatives to depleting
land resources of strategic metals such as copper, nickel, cobalt, lead, zinc, molybdenum, platinum (Cronan 1980; Rona 2003), and rare earths (Takaya et al. 2018) that are
required for various industrial as well as domestic purposes (Lenoble 2000; Glumov
et al. 2000; Kotlinski 2001) (Table 2).The largest known deposits are located in the
international seabed area, called “The Area,” and all activities in relation to these seabed resources are regulated by the International Seabed Authority (ISA) established in
1994 under the 1982 United Nations Convention on the Law of the Sea and the 1994
Agreement relating to the Implementation of Part XI of the United Nations Convention
on the Law of the Sea (www.isa.org.jm). Currently ISA has signed 17 exploration
contracts for polymetallic nodules, 7 for polymetallic sulfides, and 5 for ferromanganese/cobalt-rich crusts (Tables 3a, 3b, and 3c) in different oceans (Fig. 1a–e).

Table 1  Salient features of deep-sea minerals
Type
Polymetallic
nodules

Description
Concretions of
layered iron and
manganese oxides
with associated
metals from the

water column or
sediment

Volume
Nodules:
average
5–10 cm;
deposits: up
to thousands
of km2

Metals and their mean
concentrationa
Mn (28,4%),
Ni (13 ppm),
Cu (10,7 ppm),
Co(2098 ppm),
Mo (590 ppm),
Zn (1366 ppm),
Zr (307 ppm),
Li(131 ppm),
Pt (128 ppm),
Ti (199 ppm),
Y (96 ppm),
REEs (813 ppm)
(CCZ)

Principal
deposits
Clarion-­

Clipperton Zone,
Peru Basin,
Central Indian
Ocean and
Penrhyn Basin

(continued)


Deep-Sea Mining and the Environment: An Introduction

5

Table 2 (continued)
Type
Description
Seafloor massive Concentrated
sulfides (SMS)
deposits of sulfidic
minerals
(>50–60%)
resulting from
hydrothermal
activity on the
seabed
Ferromanganese Layered
crusts
manganese and
iron oxides with
associated metals

on hard substrate
rock of subsea
mountains and
ridges

Volume
Up to
several km2;
up to tens of
meters thick

Metals and their mean
concentrationa
Cu (0.8–17.9%),
Au (0.4–13.2 ppm),
Ag (64–1260 ppm),
Zn (2.7–17.5%),
Pb (0.02–9.7%),
Co, As, Al, Si, REEs

Mn (21%),
Up to
several km2; Co (6647 ppm),
<0.3 m thick Ni (4326 ppm),
Cu (573 ppm),
Te (34 ppm),
Mo (431 ppm),
Zr (423 ppm),
Ti (TiO2–1.4%),
Pt (0.273 ppm),

W (68 ppm),
REEs (1628 ppm)

Principal
deposits
Red Sea,
back-arc basins,
mid-oceanic
ridges, and other
plate boundaries,
oceanic hotspots
(intraplate
volcanoes)
Equatorial
Pacific Ocean
and Central
Atlantic Ocean

Modified from Cuyvers et al. (2018)
Concentrations for sulfides from Cherkashov (2017), nodules from Hein et al. (2013), and crusts
from Halbach et al. (2017)

a

Table 2  Uses and status of key metals found in deep-sea minerals
World reserves
on land in 2018
(https://www.
usgs.gov)
790 million t

Metal Main uses
Cu
Electric energy transmission (26%),
electric motors (12%), traction motor
(9%), household heating appliances
(8%), data transfer/communication (5%),
architecture and consumer goods (10%),
water supply (13%), mechanical
components (6%), electronic contact/heat
conduction (3%), car wiring (5%), others
(3%) (Zepf et al. 2014)
74 million t
Ni
Stainless/alloy steel (66%), nonferrous
alloys and super alloys (18%),
electroplating (8%), others (8%) (Zepf
et al. 2014), increasingly used in energy
storage units (e.g., Li-ion batteries)
7,100,000 t
Co
Batteries (27%), super alloys and
magnets (26%), hard metals (14%),
pigments (10%), catalysts (9%), others
(14%) (Zepf et al. 2014)

Production
rate in 2016
(https://www.
usgs.gov)

20,100
thousand t

Increase in
production
rate per
year, %
3.1

2,090,000 t

3.7

111,000 t

8.3

(continued)


6

R. Sharma and S. Smith

Table 2 (continued)
World reserves
on land in 2018
(https://www.
usgs.gov)
Metal Main uses

Mn
Metallurgy, aluminum alloys, reagent in 680 million t
(manganese
organic chemistry, batteries, coinage
content in ore)
()
Fe
Metallurgy, industry, alloys, automobiles, 83,000 million t
(iron content in
machines, trains, ships, buildings, glass
ore)
()
88 million t
Pb
Lead bullets, protective sheath for
underwater cables, construction industry,
brass and bronze, lead-acid batteries,
oxidizing agent in organic chemistry,
lead-based semiconductors (https://en.
wikipedia.org)
230 million t
Zn
Galvanizing, alloys, anode material for
batteries, manufacture of chemicals,
daily vitamin and mineral supplement,
cosmetics ()
500,000 t
Cd
Rechargeable batteries, photovoltaic
(information of

cells, pigment in paints, stabilizers in
plastics, corrosion-resistant coatings and 2014)
plating (Zepf et al. 2014)
17 million t
Mo
Carbon steel (35%), chemicals and
catalysts (14%), stainless steel (25%),
tool steel (9%), cast iron (6%),
molybdenum metal (6%), others (5%)
(Zepf et al. 2014)
69,000,000 kg
Pt
Autocatalyst (40%), jewelry (35%),
investment (6%), medical and biomedical (PGM)
(3%), glass (2%), chemicals (6%),
electrical (2%), petroleum (2%), others
(4%) (Zepf et al. 2014)
54,000 t
Au
Coinage, jewelry, industry (10%),
electrical contacts, alloys (https://en.
wikipedia.org)
530,000 t
Ag
Jewelry (34%), electronics (24%),
photography/mirrors (20%), catalysts
(6%), others (16%) (Zepf et al. 2014)
120 million t
REE Magnets (25%), catalysts (24%),
batteries (15%), polishing (11%), glass

(6%), steel (9%), others (10%)
(Zepf et al. 2014)

Production
rate in 2016
(https://www.
usgs.gov)
15,700
thousand t

Increase in
production
rate per
year, %
4.3

1450 million t 5.1
(iron content
of usable ore)
4710
2.6
thousand t

12,600
thousand t

2.9

23,900 t

1.1

279 million t

4.2

191,000 kg

1.7

3110 t

1.4

25,700 t

2.5

129,000 t

2.9


Table 3a  Contractors for exploration of polymetallic nodules

Contractor
InterOceanMetal Joint
Organization
JSC Yuzhmorgeologiya
Government of the Republic of

Korea
China Ocean Mineral Resources
Research and Development
Association
Deep Ocean Resources
Development Co.
Institut français de recherché
pour l’exploitation de lamer
Government of India
Federal Institute for Geosciences
and Natural Resources of
Germany
Nauru Ocean Resources Inc.
Tonga Offshore Mining Limited
Global Sea Mineral Resources
NV
UK Seabed Resources Ltd. – I

General location of the
exploration area under
Sponsoring State contract
Bulgaria, Cuba, Clarion-Clipperton
Fracture Zone (CCFZ),
Czech, Poland,
Russia, Slovakia Pacific Ocean
Russia
CCFZ, Pacific Ocean
Republic of
CCFZ, Pacific Ocean
Korea

China
CCFZ, Pacific Ocean

Contract start
date
29 March 2001

29 March 2001
27 April 2001
22 May 2001

Japan

CCFZ, Pacific Ocean

20 June 2001

France

CCFZ, Pacific Ocean

20 June 2001

India
Germany

Indian Ocean
CCFZ, Pacific Ocean

25 March 2002

19 July 2006

Nauru
Tonga
Belgium

CCFZ, Pacific Ocean
CCFZ, Pacific Ocean
CCFZ, Pacific Ocean

22 July 2011
11 January 2012
14 January 2013

UK and Northern CCFZ, Pacific Ocean
Ireland
Kiribati
CCFZ, Pacific Ocean

8 February 2013

CCFZ, Pacific Ocean
CCFZ, Pacific Ocean

22 January 2015
29 March 2016

CCFZ, Pacific Ocean

15 July 2016

CCFZ, Pacific Ocean

12 May 2017

Marawa Research and
Exploration Ltd.
Ocean Mineral Singapore Pte Ltd Singapore
UK Seabed Resources Ltd. – II
UK and Northern
Ireland
Cook Islands Investment
Cook Islands
Corporation
China Minmetals Corporation
China

19 January 2015

Table 3b  Contractors for exploration of ferromanganese crusts

Contractor
Japan oil, Gas and Metals National
Corporation
China Ocean Mineral Resources
Research and Development
Association
Ministry of Natural Resources and
Environment of the Russian
Federation

Companhia De Pesquisa de
Recursos Minerais
Republic of Korea

Sponsoring
State
Japan

General location of the
exploration area under
contract
Pacific Ocean

China

Western Pacific Ocean

Russia

Pacific Ocean

10 March
2015

Brazil

South Atlantic Ocean

Republic of
Korea

Western Pacific Ocean

9 November
2015
27 March
2018

Contract
start date
27 January
2014
29 April
2014


8

R. Sharma and S. Smith

Table 3c  Contractors for exploration of hydrothermal sulfides

Contractor
China Ocean Mineral Resources
Research and Development
Association
Government of the Russian
Federation
Government of the Republic of
Korea

Institut français de recherche pour
l’exploitation de la mer
Federal Institute for Geosciences
and Natural Resources of Germany
Government of India

Sponsoring
State
China

General location of the
exploration area under
contract
Southwest Indian Ridge

Russia

Mid-Atlantic Ridge

Republic of
Korea
France

Central Indian Ridge

Germany
India

Government of Republic of Poland Poland

Mid-Atlantic Ridge
Southeast and Central
Indian Ridge
Central Indian Ocean
Mid-Atlantic Ridge

Contract start
date
18 November
2011
29 October
2012
24 June 2014
18 November
2014
6 May 2015
26 September
2016
12 February
2018

Source: www.isa.org accessed on 2 December 2018

Fig. 1 (a) Exploration areas for polymetallic nodules in Clarion-Clipperton Zone, Pacific Ocean.
(Courtesy: International Seabed Authority, Jamaica). (b) Exploration areas for polymetallic nodules
and sulfides, Indian Ocean. (Courtesy: International Seabed Authority, Jamaica). (c): Exploration
areas for polymetallic sulfides on the Mid-Atlantic Ridge. (Courtesy: International Seabed Authority,
Jamaica). (d) Exploration areas for Cobalt-rich ferromanganese crusts in the Pacific Ocean.
(Courtesy: International Seabed Authority, Jamaica). (e) Exploration areas for cobalt-rich ferromanganese crusts on South Atlantic seamounts. (Courtesy: International Seabed Authority, Jamaica)

Deep-Sea Mining and the Environment: An Introduction

Fig. 1 (continued)

9


10

Fig. 1 (continued)

R. Sharma and S. Smith


Deep-Sea Mining and the Environment: An Introduction

11

Seafloor mineral exploration in the deep ocean is sometimes considered akin to
exploring beyond the normal limits of human endeavors because of the extreme
conditions associated with the deep-sea environment such as:
(i) Most deep-sea mineral deposits are located in the international seabed area, at
least 1000 km from the nearest landmass or habitation.
(ii)The deposits are associated with geological features such as deep abyssal
plains (nodules), mid-oceanic ridges and back-arc regions (sulfides), and seamounts (crusts) that generally occur at the depths of 1.5–6  km below the
ocean’s surface.
(iii) The deposits occur under extreme environmental conditions such as high pressure (150–600 bars), complete darkness, and, sometimes, complex current
regimes.
ISA has put in place regulations for prospecting and exploration for polymetallic

sulfides (ISA 2010), ferromanganese crusts (ISA 2012), and polymetallic nodules
(ISA 2013a) and, at the time of writing, exploitation regulations are being developed, with an expected completion date around 2020 (ISA 2018).

2  Key Issues of Deep-Sea Mining
Concerns of possible damages to the marine environment have been raised through
several articles in the scientific literature (e.g., Van Dover et  al. 2017). Several
benthic impact experiments conducted to understand the biological responses to
disturbances associated with nodule extraction have reported variable results due
to different means adopted for conducting the studies as well as different time
scales of monitoring on the restoration process (summarized by Jones et al. 2017).
Most of these experiments entailed plowing or suction mechanisms to mimic nodule collection and disturbing the seafloor conditions leading to vertical mixing
and lateral migration of sediments, alteration in physicochemical conditions, and
reduction in biomass (Sharma et al. 2001). Not only was the scale of disturbance
caused by these experiments much smaller than what is expected from a largescale mining operation (Yamazaki and Sharma 2001), most of these studies were
restricted to studying the impacts on the seafloor from where the minerals will
be picked up and did not include the study of secondary effects such as sediment
redistribution (i.e., sediment plumes). The concern is that the sediment plume
could smother benthic organisms (Thiel et al. 1997). It is expected that knowledge
around sediment plumes will soon be greatly advanced (e.g., through programs
such as JPI Oceans II) as projects move closer to production and collect long-term
physical oceanography data, allowing for plume modeling and then validation
testing of the anticipated plumes through, for example, component testing of prototype mineral harvesting vehicles offshore.


12

R. Sharma and S. Smith

In the water column, the main effects from full-scale mining operations are
expected to occur as a result of the presence of a lifting system designed to take the

minerals from the seafloor to the sea surface (most if not all Contractors are designing these to be fully enclosed) and the occasional passage of the mineral harvesting
tools and remotely operated vehicles.
Additionally, on board a surface vessel, the mineral will be separated from
seawater in a dewatering plant, and the seawater (and any remaining sediment)
will be discharged back to the ocean, at some depth below the euphotic (light)
zone and possibly back at depth near the seafloor (this discharge is called “return
water”).
It is also possible that there could be accidental discharges, for example, if the
lifting system were to break and all contents were lost. In this case, the impact is
expected to be short lived given the minerals should sink back to the seafloor.
Any discharge (through normal operations or accidental events) could locally
increase the turbidity in the water column at the depth of discharge, and some
spreading is likely to occur and could possibly affect productivity (Pearson 1975;
ISA 1998), although how real or large an issue this is likely depends primarily on
the depth of discharge and may not be a major issue if Contractors do as currently
expected and design their mining systems to avoid surface and shallow water mining discharges.
Transportation of several thousand tons of mineral ore to land for onshore processing would require ore carriers adding somewhat to maritime traffic in the associated region and would also increase the possibility of oil spills, accidental losses
of ship or large equipment at sea, and, also possible, although unlikely for modern
and reputable maritime operators, unintentional or intentional dumping of garbage
that cannot be monitored easily in open seas (Pearson 1975).
On land, the minerals obtained from the seafloor will be processed to recover the
metals they contain. Following mineral processing onshore, any waste or tailings
left behind after extraction of metal from the ores will need to be disposed suitably
so as to avoid the risk of serious impacts on land. Due to the often high-grade and
multi-metal nature of seafloor mineral deposits, it is anticipated that the waste generated from seafloor mining operations will be significantly less than the industry’s
land-based counterparts.
A detailed description of the likely environmental impacts of nodule, crust, and
sulfide mining is provided by Weaver and Billett (2019), Chap. 3, this volume.

3  Major Concerns Raised Around Deep-Sea Mining

In light of incomplete knowledge as well as perceived threats, several concerns are
being raised in relation to deep-sea mining that need to be addressed. Some of these
are discussed below: