Adaptive Phytoremediation Practices: Resilience to Climate Change

By Gordana Gajic, Pallavi Sharma, Madhumita Roy and Vimal Chandra Pandey

Adaptive Phytoremediation Practices: Resilience to Climate Change discusses current phytoremediation practices under an ever-pressing need for environmental remediation due to increasing pollution in a changing climate. Phytoremediation is increasingly relevant due to plants’ high effectiveness and sustainability during remediation and the ability of potential phytoremediation plants to adapt to changes in climate. Changing climatic conditions cause various biotic and abiotic stresses in plants and thereby negatively affect a plant’s establishment, growth, and yield. Therefore, the integration of suitable climate-resilient plants and adaptive remedial practices along with proper agro-biotechnological interventions is of paramount importance to mitigate the rapidly growing pollution.

This book is an important reference for environmental scientists, particularly those working in pollution management and remediation, forming an up-to-date collection of phytoremediation practices that provide sustainable solutions as a holistic approach for carrying out phytoremediation under changing climatic conditions.

• Provides up-to-date research and understanding on how to design, refine, and implement adaptive phytoremediation practices
• Focuses on enhancing resilience in plants toward climate change and explanations of the characteristics of resilient plants for adaptive phytoremediation practices in a changing climate
• Presents methods and solutions for adapting phytoremediation practices to climate change

• Language: English
• Publisher: Elsevier Science
• Release date: Feb 16, 2022
• ISBN: 9780128238325

Gordana Gajic

Dr. Gordana Gajic is Senior Research Associate in the Department of Ecology, Institute for Biological Research “Siniša Stankovic,” National Institute of Republic of Serbia, University of Belgrade, Serbia. Her research areas are phytoremediation, ecorestoration, plant ecophysiology, and biochemistry. Dr. Gajic has published more than 30 research papers in reputed journals and contributed five book chapters.

Book preview

9780128238325_FC

Adaptive Phytoremediation Practices

Resilience to Climate Change

First Edition

Vimal Chandra Pandey

Department of Environmental Science, Babasaheb Bhimrao Ambedkar University, Lucknow, India

Gordana Gajić

Department of Ecology, Institute for Biological Research Sinisa Stankovic, National Institute of Republic of Serbia, University of Belgrade, Belgrade, Serbia

Pallavi Sharma

School of Environment and Sustainable Development, Central University of Gujarat, Gandhinagar, India

Madhumita Roy

Department of Microbiology, Bose Institute, Kolkata, India

Table of Contents

Cover image

Title page

Copyright

About the authors

Foreword by Dr. Jan Frouz

Foreword by Dr. ir. Filip M G Tack

Preface

Acknowledgments

1: Phytoremediation in a changing climate

Abstract

1: Introduction

2: Global climate change

3: Impacts of climate change on growth, uptake of metals, and phytoremediation potential of plants

4: Plant-microbe interaction and their effect on metal uptake and phytoremediation in a changing climate

5: Conclusions and future prospects

References

2: Plant responses toward climatic stressors individually and in combination with soil heavy metals

Abstract

1: Introduction

2: Coping against abiotic stress condition

3: Coping against biotic stresses

4: Plant responses toward climatic stressors in combination with soil heavy metals

5: Conclusions and future prospects

References

3: Structural and functional characteristics of resilient plants for adaptive phytoremediation practices

Abstract

1: Introduction

2: Adaptive characteristics of resilient plants

3: Conclusions

4: Future perspectives

References

4: Soil and phytomanagement for adaptive phytoremediation practices

Abstract

1: Introduction

2: Soil management

3: Phytomanagement

4: Pros and cons of adaptive phytoremediation practice

5: Conclusion

References

5: Adaptive phytoremediation practices for sustaining ecosystem services

Abstract

1: Introduction

2: Adaptive phytoremediation practices—An ultimate hope for nature sustainability

3: Ecosystem services from phytoremediated polluted sites

4: Opportunities and challenges in adaptive phytoremediation practices

5: Summary and conclusion

References

6: Designer plants for climate-resilient phytoremediation

Abstract

1: Overview

2: Biotechnological strategies for generating climate-resilient phytoremediation

3: Designing and developing climate-resilient plants for adaptive phytoremediation involving OMICS approach and CRISPER-Cas9

4: Application of CRISPER to improve plant growth-promoting microbes and other features of plant growth-promoting microbes

5: Adaptive and climate-resilient phytoremediation practices

6: Designer plants in agriculture and phytoremediation through CRISPR/Cas9 system

7: Challenges and opportunities

8: Conclusion

References

7: Making biomass from phytoremediation fruitful: Future goal of phytoremediation

Abstract

1: Introduction

2: Phytoremediation and generation of heavy metal-contaminated biomass (HMCB)

3: The fate of contaminated biomass from phytoremediation

4: Bioeconomy via products recovery from contaminated biomass

5: Technologies for contaminated biomass conversion into bioenergy

6: Biodiesel, biogas, and bioethanol recovery from contaminated biomass

7: Conversion of biomass to bioelectricity

8: Other valorization of heavy metal-contaminated biomass

9: Techno-economic assessment (TEA)

10: Summary and conclusion

References

8: Policy implications and future prospects for adaptive phytoremediation practices

Abstract

1: Climatic zones and potential shift under future global warming scenario

2: Current scenario

3: Climate change effects and adaptive phytomanagement

4: Climate-smart agriculture and phytoremediation

5: Conclusion and future prospects

References

Index

Copyright

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About the authors

Vimal Chandra Pandey

Dr. Vimal Chandra Pandey featured in the world’s top 2% scientists curated by Stanford University, United States, and has published papers in the PLOS Biology journal. Dr. Pandey is a leading researcher in the field of environmental engineering, particularly phytomanagement of polluted sites. His research focuses mainly on the remediation and management of degraded lands, including heavy metal-polluted lands and postindustrial lands polluted with fly ash, red mud, mine spoil, and others, to regain ecosystem services and support a bio-based economy with phytoproducts through affordable green technology (phytoremediation). His research interests also lie in exploring industrial crop-based phytoremediation to attain bioeconomy security and restoration, adaptive phytoremediation practices, phytoremediation-based biofortification, carbon sequestration in waste dumpsites, fostering bioremediation for utilizing polluted lands, and attaining UN Sustainable Development Goals. Recently, Dr. Pandey worked as a CSIR-Pool Scientist (Senior Research Associate) in the Department of Environmental Science at Babasaheb Bhimrao Ambedkar University, Lucknow, India. Dr. Pandey also worked as Consultant at the Council of Science and Technology, Uttar Pradesh; DST-Young Scientist in the Plant Ecology and Environmental Science Division at CSIR-National Botanical Research Institute, Lucknow; and DS Kothari Postdoctoral Fellow in the Department of Environmental Science at Babasaheb Bhimrao Ambedkar University, Lucknow. He is the recipient of a number of awards/honors/fellowships and is a member of the National Academy of Sciences, India. Dr. Pandey serves as a subject expert and panel member for the evaluation of research and professional activities in India and abroad for fostering environmental sustainability. He has published over 100 scientific articles/book chapters in peer-reviewed journals/books. Dr. Pandey is also the author and editor of seven books published by Elsevier with several more forthcoming. He is associate editor of Land Degradation and Development (Wiley); editor of Restoration Ecology (Wiley); associate editor of Environment, Development and Sustainability (Springer); associate editor of Ecological Processes (Springer Nature); advisory board member of Ambio (Springer); editorial board member of Environmental Management (Springer); and editorial board member of Bulletin of Environmental Contamination and Toxicology (Springer). He also works/worked as guest editor for Energy, Ecology and Environment (Springer); Bulletin of Environmental Contamination and Toxicology (Springer); Sustainability (MDPI); and Land Degradation and Development (Wiley). Email address: [e-mail], ORCID: https://orcid.org/0000-0003-2250-6726, Google Scholar: https://scholar.google.co.in/citations?user=B-5sDCoAAAAJ&hl.

Gordana Gajić

Dr. Gordana Gajić is senior research associate in the Department of Ecology, Institute for Biological Research Siniša Stanković, University of Belgrade, Belgrade, Serbia. Dr. Gajić received her PhD from the Faculty of Biology, University of Belgrade, Serbia, on the topic Ecophysiological Adaptation of Selected Herbaceous Plants Growing on the Fly Ash Deposits of Thermoelectric Plant ‘Nikola Tesla-A’ in Obrenovac. Her main research areas are phytoremediation, ecorestoration, revegetation, ecotoxicology, environmental pollution, fly ash and mine waste phytomanagement, urban pollution, monitoring and management of polluted sites, metal(loid) exposure, plant-soil system, plant ecophysiology/biochemistry, oxidative stress, antioxidants, stress tolerance, and plant adaptive response to stress. Dr. Gajić has been involved in six research projects. She has published over 30 research papers in reputed journals and 5 book chapters with Elsevier, Nova Science Publishers, and Studium Press. Dr. Gajić is a reviewer of several reputed national and international journals.

Pallavi Sharma

Dr. Pallavi Sharma is professor in the School of Environment and Sustainable Development, Central University of Gujarat, India. Dr. Sharma is currently engaged in deciphering the mechanisms of abiotic stress tolerance in plants. She obtained her PhD in biochemistry (2005) from the Department of Biochemistry, Banaras Hindu University, Varanasi, Uttar Pradesh. She worked as a postdoctoral research fellow in the National Institute of Plant Genome Research, New Delhi, India; Department of Physics, University of Arkansas, United States; and Department of Plant Sciences, College of Agriculture and Bioresources, University of Saskatchewan, Canada, where her research was focused on MAP kinase signaling cascade in rice plants and mechanisms of cold stress tolerance and fusarium head blight resistance in wheat plants. She has published 50 scientific articles/book chapters in peer-reviewed journals/books with more than 7600 citations.

Madhumita Roy

Dr. Madhumita Roy is DST-Women Scientist in the Department of Microbiology, Bose Institute, India. Dr. Roy did her PhD work from the Microbiology Department of Bose Institute, Kolkata, and was awarded her degree from Jadavpur University in 2011. Thereafter, she did her postdoc from CSIR-IICB, Kolkata. She also worked as assistant professor at Techno India University, West Bengal. Her early research was centered on bioremediation of various kinds of heavy metals, metalloids, and xenobiotics like polycyclic aromatic hydrocarbons and then shifted to plant-based bioremediation or phytoremediation. She has published 19 articles in peer-reviewed journals, many conference proceedings, and 5 book chapters.

Foreword by Dr. Jan Frouz

Environmental pollution and climate change are serious global threats that affect ecosystem functioning as well as the well-being of humans. Phytoremediation—the use of plants to remove pollutants from soil—may help to mitigate these threats. However, phytoremediation techniques are affected by ongoing global changes. Moreover, plants enter into complex interactions with not only soil microflora but also other organisms, which make their interactions even more complex owing to the ongoing global changes. Therefore, there is a pressing need for plant scientists to develop a holistic approach to reduce the ever-increasing number of pollutants in the scenario of changing climate. In this context, this book, Adaptive Phytoremediation Practices: Resilience to Climate Change, offers a promising way against pollutants in the changing climate as an ultimate hope for the sustainability of nature. The book also pays considerable attention to the multiple benefits of ecosystem services of phytoremediated polluted sites and also provides insights into how plants, polluted sites, and adaptive phytomanagement practices can be used to improve resilience to untoward incidents such as drought, salinity, heavy metal toxicity, which has become very necessary for effective phytoremediation in the changing climate.

Climate-resilient phytoremediation is gaining attention globally due to the mixing of climate change and ecosystem pollution. Changing climatic conditions also cause various biotic and abiotic stresses in plants and thereby negatively affect plant establishment, growth, and yield. Therefore, the integration of suitable climate-resilient plants and adaptive remedial practices along with proper agro-biotechnological interventions are of paramount importance to mitigate the rapidly growing pollution. Application of soil amendments, inoculation of microbes (fungi and plant growth-promoting rhizobacteria), selection of climate-resilient plants, and genetic engineering are techniques used to sustain phytoremediation in the changing climate. Currently, there is no book available in the market that can cover this novel topic, Adaptive Phytoremediation Practices: Resilience to Climate Change. This book can be considered a single source of phytoremediation knowledge on adaptive phytoremediation practices in a changing climate. It is the first book that covers this unique and novel topic and will enjoy a wide readership. Overall, this book is an excellent, up-to-date, and highly informative resource; it is a timely contribution that has a simple-to-understand and easy-to-read format. It contains rich literary text of great depth, clarity, and coverage from which scientific knowledge can grow and widen in this field.

I appreciate the efforts of the authors, Dr. Vimal Chandra Pandey, Dr. Gordana Gajić, Dr. Pallavi Sharma, and Dr. Madhumita Roy, in bringing out this valuable book with the help of the leading global publisher, Elsevier. The book comprises eight chapters covering various aspects of the integration of phytoremediation and climate change. I hope this book will be a remarkable asset for researchers, PhD scholars, plant scientists, policy makers, practitioners, entrepreneurs, and other stakeholders alike.

Jan Frouz, Environmental Centre, Charles University, Prague, Czech Republic

Foreword by Dr. ir. Filip M G Tack

Concerns about the pollution of our environment have recently been augmented by significant worries about the effects of human activities on global climate change. Since the early 1970s, awareness rose that uncontrolled release of contaminants into the environment is threatening the ecosystem and human health. Only very recently, and despite early warnings, it has been universally accepted that massive emissions of carbon dioxide and methane during the industrial development and agricultural intensification of modern society are one of the main factors causing a rapid unfavorable worldwide change in climate as a result of global warming. The transition will be hard. It will need to be fast, or humanity will fail.

Meticulously preserving our 20% wilderness that remains and restoring additional wildland will be crucial to restore the resilience and stability of the earth’s climate system. Harm to the environment was also done at many other levels and scales. Plants will play a central role in mitigating or undoing the harm. The need for science to develop more integrated approaches to mitigate environmental damage and ultimately climate change has never been so urgent. In this context, the present book, Adaptive Phytoremediation Practices: Resilience to Climate Change, highlights the potential role of plants in environmental technology to counter adverse environmental effects that resulted from unsustainable human development. It highlights the benefits of phytoremediated polluted sites, which can provide multiple ecosystem services. The book provides insight into how adaptive phytomanagement practices can lead to remediation of degraded and contaminated sites through the establishment of plant systems that are resilient against untoward incidents such as drought, salinity, and heavy metal toxicity.

Climate-resilient phytoremediation is gaining attention worldwide due to the links between the problems of climate change and of ecosystem pollution. Changing climatic conditions cause various biotic and abiotic stresses in plants, negatively affecting the establishment of plants and their health, strength, and growth performance. Selection of suitable climate-resilient plants must be combined with adequate remedial practices including adapted agronomic and (bio)technological interventions. Application of soil amendments, inoculation of microbes, selection of climate-resilient plants, and genetic engineering are tools within sustainable phytomanagement strategies in a changing climate. No earlier publications made such a strong connection between issues of contaminant management and threats to humanity related to climate change. The book Adaptive Phytoremediation Practices: Resilience to Climate Change is an up-to-date and timely contribution, presented in a way that is accessible to a wide multidisciplinary audience.

I am happy to recognize the efforts of the authors, Dr. Vimal Chandra Pandey, Dr. Gordana Gajić, Dr. Pallavi Sharma, and Dr. Madhumita Roy, in creating this valuable work with the help of the leading global publisher, Elsevier. The book comprises eight chapters covering various aspects of phytoremediation in connection with climate change. I believe this book will be a valuable asset for students, researchers, policy makers, practitioners, entrepreneurs, and other stakeholders alike.

Filip M.G. Tack, Department of Green Chemistry and Technology, Ghent University, Ghent, Belgium

Preface

Vimal Chandra Pandey

Gordana Gajić

Pallavi Sharma

Madhumita Roy

Adaptive Phytoremediation Practices: Resilience to Climate Change presents phytoremediation practices in the scenario of changing climate and plant responses to stress. The book provides a brief overview of different aspects of adaptive phytoremediation practice and responses of plants to climatic stressors and pollution. It presents the current state of research on structural and functional characteristics of resilient plants and advancements in the knowledge on lipidomics and designer plants that can be applied in agriculture and phytoremediation using gene editing tools such as the CRISPR/Cas 9 system. The book covers all aspects of soil and phytomanagement and offers prospects for the development of climate-resilient economic crops. It aims to provide knowledge on the bioeconomy of contaminated biomass, ecosystem services, and policy frameworks. Appropriate green remediation strategies are essential for climate, energy, agricultural, and food policy domains linking the environment, people, markets, assets, and finance to conserve natural resources and improve human health and well-being worldwide. This book will be ideal for students, researchers, environmentalists, ecological engineers, regulatory agencies, policy makers, and other stakeholders.

Chapter 1 provides general information about the impacts of climate change on plant growth and metal uptake together with plant-microbe interaction to help readers better understand the impacts of elevated CO2, temperature, and drought on plants. Chapter 2 covers plant responses to abiotic and biotic stresses, such as high temperatures, drought, salinity, cold, flood, heavy metals, and pests, highlighting plant tolerance. Chapter 3 elaborates the functional and structural responses of resilient plants to climate change and pollution with a focus on plant physiology, biochemistry, anatomy, and morphology. Chapter 4 provides a detailed overview of soil management using arbuscular mycorrhizae against drought and salinity stress and rhizobacteria and industrial and organic wastes in the management of degraded soils, with special emphasis on biofuel, fiber, aromatic essential oil, and fortified crop production and their role in phytoremediation. Chapter 5 focuses on phytoremediation strategies and ecosystem services for polluted sites through provisioning, regulating, and supporting services. A detailed review of biotechnological strategies for the generation of designer plants for climate-resilient phytoremediation involving the application of CRISPER for cold, salt, heat, and drought plant tolerance, and improvement of their yields, quality, and nutrition, is presented in Chapter 6. Making biomass from phytoremediation; detailed information on biochemical and thermochemical processes; the recovery of biodiesel, biogas, bioethanol, and dye from contaminated biomass; the conversion of biomass to bioelectricity; and making bioenergy from farm waste are covered in Chapter 7. Finally, Chapter 8 describes the status of remediation and policy implications, climate smart agriculture, and phytoremediation all of which aim to create a greener and sustainable economy for the protection of the environment and human health around the globe.

Acknowledgments

We sincerely thank Peter J. Llewellyn and Marisa LaFleur (acquisitions editor), Aleksandra Packowska (editorial project manager), and Swapna Praveen (copyrights coordinator) and Joy Christel Neumarin Honest Thangiah (production project manager) from Elsevier for their excellent support, guidance, and coordination during the production of this fascinating project. We would like to thank all the reviewers for their time and expertise in reviewing the chapters of this book. Vimal Chandra Pandey is grateful to the Council of Scientific and Industrial Research, Government of India, New Delhi, for the support under Scientist’s Pool Scheme (Pool No. 13 (8931-A)/2017). Gordana Gajić is thankful to the Ministry of Education, Science and Technological Development of the Republic of Serbia (No. 451-03-9/2021-14/200007) for their support. The authors are thankful to Dr. Jan Frouz, Professor and Director, Environmental Centre, Charles University, Prague, Czech Republic, and Dr. ir. Filip M.G. Tack, Professor in Biogeochemistry of Trace Elements, Department of Green Chemistry and Technology, Ghent University, Belgium, for writing the foreword at short notice. Finally, we thank our respective families for their unending support, interest, and encouragement, and apologize for the many missed dinners!

1: Phytoremediation in a changing climate

Abstract

Anthropogenic activities have generated an enhanced level of many toxic contaminants including heavy metals in the environment. Enhanced level of heavy metals is a major environmental concern globally because of their hazardous effect on living organisms. Plants belonging to various species can fix contaminant in roots, accumulate them in leaves, or metabolize toxic contaminants into nontoxic or less toxic forms. Phytoremediation strategy uses these plants for an effective remediation of contaminant. It is cost-effective, eco-friendly, and less destructive to soil microbial activity. Also, transgenic plants with efficient phytoremediation ability have been made. However, the application of this strategy at the field scale is limited by various factors, including varying environmental conditions. Climate change can affect the plant growth as well as availability of contaminant in soils by altering the structure and function of plant roots and the activity and diversity of associated microbes. Due to growing risk and uncertainty of climate change, strategies should be made that enable plants to grow well in contaminated land as well as to tolerate changing climate.

Keywords

Changing climate; Elevated CO2; Elevated temperature; Drought; Phytoremediation; Heavy metals; Metalloids; Plant growth; Metal uptake; Plant-microbe-metal interaction

Chapter outline

1Introduction

2Global climate change

3Impacts of climate change on growth, uptake of metals, and phytoremediation potential of plants

4Plant-microbe interaction and their effect on metal uptake and phytoremediation in a changing climate

5Conclusions and future prospects

References

1: Introduction

Various human activities, including industrial, mining, and agricultural, result in contamination of air, soil, and water with various pollutants (D’Surney and Smith, 2005; Mishra et al., 2020; Majhi et al., 2021; Pandey and Bauddh, 2019; Pandey, 2020a,b). These contaminants show an adverse impact on living organisms (Alloway, 2013; Nsanganwimana et al., 2014; Pandey, 2020b). Therefore, sustainable and effective management of polluted lands is indispensable (Pandey and Bauddh, 2019; Pandey, 2020a). Traditionally, chemical and physical technologies, including chemical desorption, soil washing, incineration, and solidification, have been utilized for the remediation of contaminated sites (González-Moscoso et al., 2019). Although suitable for point source pollution, these technologies are unfeasible for handling large areas. Also, these procedures are costly and noneco-friendly.

Phytoremediation is a green, eco-friendly, and cost-effective alternative for soil remediation in large-polluted areas with multiple benefits (Pilon-Smits, 2005; Yan et al., 2020; Pandey and Bajpai, 2019; Pandey and Souza-Alonso, 2019; Pathak et al., 2020; Mishra et al., 2020; Praveen and Pandey, 2020) and has received great attention. The approach depends on plant’s capability to neutralize or mitigate the harmful effect of contaminants (Salt et al., 1995; Pandey et al., 2015). Phytoremediation includes many different plant processes, including (i) phytovolatilization, which involves uptake and transfer of the harmful substance to the air; (ii) phytostabilization, which reduces the mobilization of the contaminants and leaching; (iii) phytoextraction, which involves the taking up and accumulation of contaminants in the tissues. Microbe-assisted phytoremediation (MAP) is considered a very effective and useful approach to remediate soil contaminated with metals. The cohesive interaction between microbes and plants may trigger plant growth, provide enhanced resistance to abiotic stresses and disease, and promote adaptation to contaminated environments, and thus can play a vital part in phytoremediation (Ashraf et al., 2017).

Climate change is of utmost environmental concern which the whole world is facing due to its adverse impacts on all living organisms, including plant. Volcanic eruptions, Sun’s intensity, and alterations in concentration of greenhouse gas (GHG) contribute to earth’s climate change (IPCC, 2013). GHG emissions due to anthropogenic activities are the principal reason of the fast-changing climate. Natural sinks of carbon such as planet’s forest (photosynthesis) and oceans are not able to keep up with the rising emissions of GHG so there is build-up of GHG, which is causing disturbingly rapid warming worldwide (Denchak, 2017). Major threats associated with climate change include drought, flooding, high-temperature land salinization etc. It has potential to make environmental stresses more intense and accelerate the processes to make them set in regions where they were not present earlier (El Massah and Omran, 2015).

Climatic change and associated stresses have potential to affect growth, development, and metal uptake by plants (Fig. 1). It can alter the allocation of photosynthate in rhizosphere resulting in changed microbial composition, and thus influence the uptake of metals by plants and hence efficiency of phytoremediation (Compant et al., 2010; Guenet et al., 2012; Dutta and Dutta, 2016). This chapter will give an overview of the global climate change, associated environmental constraints, and their impact on plant growth, metal uptake, plant-microbe-metal interaction, and phytoremediation.

Fig. 1

Fig. 1 Climatic change and associated stresses have potential to affect plant growth and development and hence phytoremediation efficiency of plants.

2: Global climate change

Climate changes before industrial revolution during the 1700s may be attributed to natural causes, including volcanic eruptions, alterations in solar energy, and natural variations in GHG such as carbon dioxide (CO2), water vapor, methane (CH4), ozone (O3), and nitrous oxides (NxO) (IPCC, 2013). However, natural causes singly cannot explain current climate changes. Warming from the mid of 20th century has been attributed mainly to human activities. Fossil fuel (coal, oil, and gas) burning for heat, electricity, and transportation and deforestation are leading sources of anthropogenic emissions of GHG. Other anthropogenic activities like fertilizer usage (nitrous oxide), production of livestock (CH4), and some industrial processes (fluorinated gases) also lead to GHG production. GHG absorb thermal infrared (IR) radiation, which is discharged by the surface of Earth and atmosphere and, in turn, emits IR radiation, with a substantial part of this energy used in warming the surface of Earth and lower atmosphere (Ledley et al., 1999). Increased GHG emissions can provoke extreme climate changes such as heat, floods, and droughts. Some GHGs such as CH4 can persist for up to decades, whereas CO2 stays for centuries to millennia (Zickfeld et al., 2017). The concentration of CO2, which is the earth’s main climate change contributor, has enhanced by >  40% due to various human activities since preindustrial times. The atmospheric global CO2 growth rate was around 0.6 ± 0.1 ppm year−  1 during the 1960s. However, between 2009 and 2018, the rate of growth was 2.3 ppm year−  1. The CO2 was around 409.8 ± 0.1 ppm (global average) in year 2019, an increase of 2.5 ± 0.1 ppm compared to 2018. By this century end, atmospheric CO2 is expected to be around 700 ppm (Lindsey, 2020).

Rising CO2 can affect plant metabolism both directly and indirectly. CO2 has an important role in photosynthesis so it can directly affect photosynthesis. Indirectly, it can affect plant performance via its impact on temperature and drought (Dusenge et al., 2019). Increased CO2 concentration amplifies Earth’s greenhouse effect. Strong correlation between CO2 concentration and air temperature has been noted throughout glacial cycles in past numerous hundred thousand of years. When the CO2 concentration increases, temperature also goes up. Also, anthropogenic activity-induced climate change has also led to incidence and intensity of temperature extremes (Meehl et al., 2007; Seong et al., 2021). IPCC estimated that by the year 2100, an increase in temperature will be between 1.8°C and 4.0°C (IPCC, 2014). Heat waves or extreme temperature events are projected to become more intense, more frequent, and last longer than what is being currently observed (Meehl et al., 2007). Daily minimum temperatures are suggested to increase more quickly compared to daily maximum temperatures causing increased daily mean temperatures and a higher risk of extreme events, which can cause damaging effects on plant (Meehl et al., 2007). As temperature is among the key environmental factor controlling the plant growth and development (Hatfield and Prueger, 2015), the responses of plant to temperature variations have become a major concern nowadays.

Inconsistency in temperature and occurrence of precipitation may lead to a rise in water scarcity. Therefore, due to global warming and change in climatic conditions, changes in distribution, the frequency, severity, and duration of drought are expected to increase in the future. For 21st century, a steady rise in aridity has been projected by Global climate models (Scheff and Frierson, 2015; Zarch et al., 2017; Greve et al., 2019). According to these projections, drylands will possibly expand due to surges in evaporative demand and a hydrological cycle having extended and more severe dry periods at the worldwide scale. Also, an enhancement in soil salt concentration and a reduction in water quality may lead to soil salinization, which may cause land degradation (Tomaz et al., 2020). River flood hazard may also increase owing to climate alteration (Prudhomme et al., 2003; Hirabayashi et al., 2013; Avand et al., 2021). Although warming may not trigger floods, it influences snowmelt and rainfall that can contribute to flood. Climate change can have positive as well as negative effects on pathogens and pests. It can lead to alterations in their population dynamics, abundance and diversity, biotypes, geographical distribution, interactions with plant, natural enemies, and extinction. Increased pests and pathogens infestation due to climate change are projected to cause reduced crop yields (Dhankher and Foyer, 2018).

3: Impacts of climate change on growth, uptake of metals, and phytoremediation potential of plants

Phytoremediation potential (metal extraction and stabilization of contaminants) of plants depends on different factors like bioavailability of metal in soils, plant biomass, metal accumulation capability, microbiome, and climatic factors (Glick, 2010; Grčman et al., 2001; Miransari, 2011). Any abiotic parameter that influences these factors should also affect phytoremediation efficacy. Climate change and stresses associated with it such as elevated CO2 (EC), temperature, and drought can alter the plant growth and metal uptake and accumulation potential of plants. Different effects of EC, drought or warming, or a combination of climatic stress on metal accumulation and growth of plants differ greatly across plants used and chemical, biological, and physical characteristics of environment. These properties include pH of the soil, type of heavy metals and their bioavailable concentrations, diversity of microorganisms, and effects of climatic factors interaction (Rajkumar et al., 2013). Consequently, it is important to understand the interaction between climate change, growth of plant, and metal uptake and accumulation. Understanding the climate change effect on plant growth and metal accumulation can be beneficial when developing phytoremediation strategy for particular contaminated sites (Brunham and Bendell, 2011).

3.1: Impacts of elevated concentration of CO2

Elevated concentration of CO2 or EC alters the growth, metal uptake, and phytoremediation efficiency of plants (Table 1). It is widely recognized that EC can stimulate photosynthesis and plant biomass with the degree of stimulation being species or cultivar dependent (Ziska et al., 2012). Faster growth and greater biomass, in turn, could enhance phytoextraction and toxin uptake in aerial plant tissue. EC can augment plant biomass by 50% via CO2 fixation (Dier et al., 2018). It can enhance plant height, dry weight, and the leaf area by stimulating photosynthesis (Khanboluki et al., 2018). As CO2 increases, the stomatal pores don’t open as wide, leading to decreased conductance of stomata (gs), lower transpiration, and increased intrinsic water-use efficiency (WUEi) (Jarvis et al., 1999; Aranjuelo et al., 2006; Erice et al., 2006; Long et al., 2006). Högy et al. (2010) reported that EC (409 ppm versus 537) enhanced biomass and concentration of metabolites of low molecular mass in several weed species. In comparison with herbaceous species, heavy metal accumulator plants, poplars, and willows were found to be more EC responsive (Ainsworth and Long, 2005), as evident by their biomass, height, and carbon assimilation, which was suggested to be the result of stimulatory effect of EC on the photosynthetic rate and expansion of leaf (Curtis and Wang, 1998; Nowak et al., 2004). However, long-term continuous EC exposure may lead to a reduction (downregulation) of photosynthetic capacity. Often this decrease is accompanied by decreased photosynthetic enzymes and pigments such as ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) (Faria et al., 1996; Centritto and Jarvis, 1999). Goufo et al. (2014) observed that elevated CO2 increased the accumulation of carbon in rice throughout its whole life cycle.

Table 1

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ROS have been related to the inhibition of growth, utilization of nutrients, and photorespiration of plants. Since heavy metals increase ROS generation, it is hypothesized that CO2 can reduce damaging effects of metals on plants. EC levels led to increased plant growth, uptake of Cd, rate of assimilation CO2, efficiency of intrinsic water use and activities of antioxidative enzyme, decreased gs, transpiration rate and malondialdehyde (MDA), and no change in Cd concentrations in poplar genotype (NL95) and willow genotype (J172). It was proposed that EC promoted the growth of plant by boosting photosynthesis and increased phytoremediation efficiency, mainly at high Cd content (Guo et al., 2015). Cd accumulation due to EC differed in Cd-tolerant wheat and sorghum. EC reduced Cd contents in roots and shoots of Cd-tolerant wheat, while it enhanced for Cd-tolerant sorghum plants (Khanboluki et al., 2018).

Accumulation of metal and biomass in Noccaea caerulescens increased under EC (550 ± 50 ppm) compared to controls (400 ppm CO2), suggesting that the EC could increase phytoremediation efficiency. Concentrations of water-soluble and exchangeable Cu and Pb decreased in soil under EC conditions, which decreased the risks of leaching of these metals. MDA concentrations in N. caerulescens reduced to varying degrees with the EC. It was hence suggested that EC can decrease oxidative damage resulting from metals in this species (Luo et al., 2019). EC (860 μL L−  1) caused 32%–111% increased aerial biomass of the Sorghum and 8%–11% in Trifolium species in comparison with ambient CO2. It also caused up to 73% increased Cs accumulation in Sorghum and 43% in Trifolium species (Wu et al., 2009). At EC (1200 μL L−  1), both Indian mustard and sunflower showed increased leaf area, biomass, and Cu extraction capability compared to when grown under ambient CO2 (Tang et al., 2003). Increased photosynthetic efficiency, Cd accumulation, antioxidant capacity, growth, and Cd phytoremediation capability of Lemna minor with increased Cd treatments, time of exposure, and EC (350 and 700 ppm) were observed (Pietrini et al., 2016). Cd toxicity alleviation at low Cd treatments at EC in L. minor may be credited to enhanced photosynthesis and increased antioxidant capacity. Long-term EC increased the phytoextraction of Pb by Robinia pseudoacacia from contaminated soils (500 mg kg−  1 soil) (Jia et al., 2018). Increased accumulation of Pb in leaves and removal of Pb from soils were observed. Width and height of seedlings increased due to EC in comparison with ambient CO2. EC led to increased SOD and CAT activities and higher concentrations of cystine, glutathione, phytochelatin, phenolics, proline, and flavonoids in plants under Pb treatment. EC (800 μL L− 1) stimulated the growth of Sedum alfredii nonhyperaccumulating and hyperaccumulating ecotype but an increase was much greater in hyperaccumulating ecotype. EC was proposed to be an approach to increase phytoremediation efficiency of S. alfredii hyperaccumulating ecotype (Li et al., 2013).

EC increased Arabidopsis thaliana biomass (aerial) significantly. However, the level of stimulation of biomass was dependent on ecotype. At As concentration of 110 μM, the relative effect of EC was to reduce both As concentration and As uptake per plant; however, genetic variation was also obvious among A. thaliana for As phytoextraction at existing and expected CO2 levels (Fernandez et al., 2018). EC (360 and 1000 μL L−  1) led to more increase in shoot biomass than in root biomass of Lolium perenne and Lolium multiflorum exposed to 4 and 16 mg Cd L−  1 but reduced Cd concentrations in all plant tissues (Jia et al., 2011).

3.2: Impacts of elevated temperature

Temperature influences the growth and development rate of plants. It can also influence metal uptake by plants (Table 2). Each plant species has a particular temperature range characterized by an optimum, maximum, and minimum. Responses of plants to temperature increase depend on the plant development stage. For most species of plants, vegetative development generally has a greater optimum temperature compared to reproductive development. Temperature may affect water chemistry and growth of plants (Fritioff et al., 2005). It alters plant transpiration rate, metabolism, and growth and thus influences uptake and elimination of contaminants (Yu et al., 2005). Changes in temperature show the large impact on the uptake and accumulation of metals by plants. Therefore, it is imperative to understand the relation between temperature change, plant growth, and uptake and accumulation of metal when planning for phytoremediation in different bioclimatic zones (Brunham and Bendell, 2011). Fastest growth happens around 15 and 30°C in most plants (Larcher, 1995). Application of higher temperatures in the field can minimize the time duration required to attain clean-up aims. Baghour et al. (2001) observed higher Cr uptake by Spunta variety of Solanum tuberosum at high temperature compared to low temperature. Metal transfer from soil to plant was more at higher temperature in Potamogeton natans, Elodea canadensis (Fritioff et al., 2005), willow (Yu et al., 2010), and safflower (Pourghasemian et al., 2013) for various metals (Cd, Cu, Cr, Zn, Pb). This was suggested to be due to enhanced plant growth and uptake of metals by roots under warmer temperatures. Temperature increase (26 and 30°C) enhanced Cr toxicity by reducing photosynthesis and growth and increasing activities of antioxidative enzymes in Atriplex halimus. It also increased nutrient uptake and translocation but decreased Cr translocation. At 1 mM Cr treatment, Cr concentration in roots at 26°C was 7.2 g kg−  1 and at 30°C was 9.1 g kg−  1, respectively, whereas Cr concentration in the shoot was 0.45 at 26°C and 0.44 g kg−  1 at 30°C (Mesnoua et al., 2018).

Table 2

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Shah et al. (2013) reported enhanced Cd uptake and accumulation in vacuoles, parenchyma, and vascular cylinder and stimulated antioxidant system in rice cv. Bh-1 roots subjected to a combination of heat stress and suggested that heat stress may mitigate mild Cd toxicity directly by an increased formation of Cd²  +-MT providing Cd²  + tolerance. The removal rates of Cr(VI) and Cr(III) by plants showed a linear relation with a temperature rise from 11°C to 32°C. The rate of Cr(III) and Cr(VI) removal was the highest at 32°C. Cr(VI) and Cr(III) translocation was observed from the root to the lower stem. Cr(VI) removal using hybrid willow was more vulnerable to alterations in temperature compared to Cr(III) (Yu et al., 2010).

Efficient transfer of metals from soil to plants is good for phytoremediation purpose. Therefore, improved understanding of how the temperature affects the metal bioavailability in cultivated soils is important. Dissolved organic matter (DOM) is the main metal complexing substance in soil, whereas soil organic matter (SOM) is the prominent metal-carrying phase in soil. Content and properties of the organic matter determine the metal complexation and mobility in soil. The temperature increase is suggested to stimulate the metal mobilization via influencing the SOM degradation and altering the metal complexation in water present in pores by changing the nature and quality of DOM (Cornu et al., 2011). In lettuce crop, a consistent decrease in bioavailability of Zn and Cd was reported from 10°C to 30°C, and this was credited to a strong metal complexation in the pore water because of a rise in soil temperature at higher temperatures. However, Zn and Cd transfer from soil to plant was stimulated at higher soil temperatures, suggesting that this process was affected most at higher temperature (Cornu et al., 2016).

In many cases, plant growing under high temperature condition showed the promotion of plant growth, increased photosynthetic rate, and accumulation of greater amount of heavy metals. Temperature-led indirect effects, such as SOM decomposition, on metal mobilization and/or uptake have been suggested the reason for higher metal accumulation (Sardans et al., 2008; Van Gestel, 2008; Conant et al., 2011).

3.3: Impacts of drought

Drought can be critical in areas with low availability of water or random alteration in weather during plant growth period. The effects of drought are likely to increase with climate change and growing water scarcity. It is a major environmental stress factor that affects the growth and development of plants. Understanding of relation of drought, plant growth, and metal uptake is necessary for phytoremediation under climate change. Variable effects of drought on phytoremediation potential of plants were reported in metal-polluted soils. In tall fescue, low soil moisture increased the accumulation of Se and reduced the production of biomass. Overall, drought reduces the heavy metal phytoremediation potential of plants (Tennant and Wu, 2000). High drought stress may harm many functions of plants but the main consequence is a decrease of carbon fixation, which causes a decreased plant growth depending on duration of the stress, the stage, and the existence of other stresses. However, Angle et al. (2003) observed higher biomass and uptake of metal such as Zn or Ni by plants at higher soil moisture leading to greater concentration of metals extracted from soil in Alyssum murale, Berkheya coddii, and Thlaspi caerulescens. Beta vulgaris plants grown in Cd-polluted soil [controlled deficit irrigation (300 L: T1, 200 L: T2, 100 L: T3)/block at each irrigation] throughout the organogenesis stage. The shoot biomass increased by 15.8%, and efficiency of Cd phytoremediation potential under T2 treatment (5.42 g ha−  1) was 39.7% higher compared to T1 and 61.8% higher than T3 (Tang et al., 2019b).

Water is needed for many biochemical and physiological processes, including germination, division and elongation of cells, various metabolic activities including organic compounds synthesis, respiration, and photosynthesis (Lange et al., 2012). Drought leads to lower height, decreased leaf number and size, and less production of fruit. It also causes stomatal closure and increased resistance to CO2 diffusion in leaves (Alizadeh et al., 2015). Study on the structure of xylem and hydraulic conductivity revealed that metal stress exacerbates water stress in an additive manner and thus makes the Acer rubrum plants more sensitive to drought (de Silva et al., 2012). However, the effect of metal stress and combination of drought and metal toxicity on the plant growth did not differ greatly, suggesting that drought stress did not make plants extra vulnerable to metal stress (Ma et al., 2016b). Photosynthetic performance such as gs, chlorophyll fluorescence, and chlorophyll concentration declined. Water status of plant was the last affected parameter by the drought treatment (Ings et al., 2013). Water deficit also reduced the transfer and concentration coefficient of different metals, including Cu, Zn, Ni, and Mn in L. multiflorum Lam. roots in the soil in which rural sewage sludge was amended in high amount (Pascual et al., 2004). Drought reduced the transfer and concentration coefficient of some heavy metals in the root of sewage sludge (SS), mineral fertilizer (M)-treated plants, indicating that heavy metals in sewage sludge were preserved in chemical forms with low availability (Pascual et al., 2004).

Cd-treated wheat plants grown for 125 days after seed sowing had lesser biomass and greater oxidative stress and drought treatment further reduced the biomass of plant and resulted in oxidative stress. In wheat tissues, drought enhanced the Cd content (Khan et al., 2019). In Indian mustard plant, drought stress at 90 day after sowing led to a decreased Cd uptake (Bauddh and Singh, 2012). When corn plants were irrigated with water containing 0, 5, 10, and 20 mg Cd L−  1 at 1-, 3-, and 7-day irrigation intervals, toxicity symptoms of Cd appeared clearly on the plant. Stem dry weight, transpiration, and height of plant were most sensitive to Cd levels. Cd accumulation was 24%, 56%, and 27% more at 1-, 3-, and 7-day irrigation interval in leaves compared to stems, indicating that corn can be