Reviews: Books

Kate Kennen and Niall Kirkwood :


Principles and Resources for Site Remediation and Landscape Design

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Hazardous pollutants that exist in contaminated soils represent a threat to human, animal, and environmental health if left unmanaged. Phytoremediation in the United States was generally named and formally established in the 1980s and applied as an alternative method of using plants to cleanse contaminated soils on-site in a more economically and environmentally friendly way than removing contaminated soils off-site. This method utilizes vegetation to remediate, contain or prevent contaminants in soils, sediments and groundwater, and/or add nutrients, porosity and organic matter. Unrealistic expectations and mixed performances with failures outnumbering successes led to a decline in environmental research funding phytoremediation by the early 2000s.
     Phyto, by landscape architects Kate Kennen and Niall Kirkwood, invigorates phytoremediation in landscape architecture. While the term “phytoremediation” is prevailing in research, Kennen and Kirkwood use the broader definition of “phytotechnology,” which better suits the more comprehensive approach applicable to landscape architecture. It includes natural systems, considers multiple scales between site and region, emphasizes prophylactic approaches, includes green infrastructure, and addresses the need to incorporate cultural values. “Phytotechnology is about using specifically selected plants, installation techniques, and creative design approaches to rethink the landscapes of the post-industrial age.1 Kennen is a registered landscape architect in Boston, Massachusetts, with a practice that is focusing on productive planting techniques and phytotechnology consulting. Kirkwood is a landscape architect and professor at the Harvard Graduate School of Design. He is one of the pioneers of phytotechnology and brownfield remediation in landscape architecture.
     In Phyto, Kennen and Kirkwood target a larger audience to make the complexity of phytotechnologies more approachable for the landscape design profession. This applies especially to students of landscape architecture and planning design students in general, practitioners in landscape architecture, planning, or environmental engineering, the horticultural industry, and landscape construction or land care associations. The authors have synthesized hundreds of scientific articles from prominent sources such as the International Journal of Phytoremediation and research-based landmark books on phytoremediation. They worked with forty-seven highly accomplished specialists in bioremediation and revitalization of postindustrial landscapes, who contributed by synthesizing scientific content, providing case studies, and providing overall review. Prominent contributors are environmental engineering pioneers such as Steven Rock and Jerald Schnoor.

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     Kennen and Kirkwood have organized the book into six chapters. The first chapter provides an overview of phytotechnologies and their current applications in the environment and their anticipated future use. The second chapter reviews the fundamentals of the scientific processes involved in phytotechnology remediation (Figures 1 and 2). This chapter deals with general processes in the plant, gives a brief overview of contaminant types, describes the processes or mechanisms in the plant that assist in the remediation of contaminants, covers installation characteristics, and introduces the challenges and limitations of field application. The third chapter classifies the contaminants commonly addressed by phytotechnology approaches and provides a guide to plant selection that is applicable to all climate zones in North America. This chapter adds complimentary case studies for all classified contaminants to further illustrate successful phytotechnology installations in praxis (Figure 3). Chapter 4 outlines the interrelationships of specific contaminants with eighteen different phytotechnology planting typologies or “Phytotypologies.” Each typology is introduced with its corresponding major phytoremediation mechanisms. These are remediation processes that take place within or around the plant, the target media—for example, soils or groundwater—and the contaminants addressed/not addressed. Additionally, typical applications of the planting typology are briefly described in land-use scenarios, as well as general plant-selection criteria and other design considerations. The eighteen phytotypologies depicted can be used as interchangeable modules in the design process to address the specific challenges of the site, including contamination (Figures 4–7). 

Figure 1. Summary of eight primary mechanisms of phytotechnologies
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Figure 2. Phytodegradation: organic contaminants are broken down in the roots, stems, and leaves of the plant. 
Figure 3. Case study: remediation of organic petroleum compounds through the planting of poplar trees at the Ford Factory in Genk, Belgium. 
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Figure 4. Phytotypology: groundwater migration tree stand.
Figure 5. Phytotypology: degradation bosque.
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Figure 6. Phytotypology: multi-mechanism buffer.
Figure 7. Phytotypology: phytoirrigation.
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     Chapter 5 applies the phytotypologies developed in chapter 4 to a range of sixteen commonly found land-use scenarios such as roadways, river corridors, gas stations, railroad corridors, and the like. These case studies are depicted with diagrammatic drawings showing the potential sources of contamination (Figure 8) and possible phytotechnologies (Figure 9). Tables are assigned to the diagrams that briefly describe issues and solutions while precisely referring to other chapters and pages in the book for further explanation. The diagrams suggest combining these phytotypologies to create a comprehensive and aesthetically pleasing design solution that may clean contaminants or take preventive measures. The last chapter lists additional resources, such as online databases and selective literature to follow up on specific areas. Finally, commonly used terms of phytotechnologies are explained in the four-page glossary. The bibliography, with close to 700 entries, demonstrates the high standards of the authors and their goal to bridge the hard sciences with creative application in planning and design. These entries provide readers important references for further research and information.
     Rather than beginning with the first chapters and the introduction to phytotechnologies, it is possible to approach the subject with the land-use scenarios in the fifth chapter. These provide a brief introduction without omitting potential sources of contamination, a listing of major contaminants, and tangible spatial solution with an assemblage of possible planting typologies. The informative tables with short descriptions reference other more specific and detailed sections in the book. The continuous color code in the book for contaminants is helpful to readers—especially those who are new to the complexity of phytotechnology. Obviously these planting typologies need to be expanded, connected, and combined creatively to create a coherent and more artistic design solution in the landscape. While the landscapes and planting zones addressed in Phyto are generally developed from a North American perspective, they can be applied in other settings worldwide with similar constellations. 

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Figure 8. Land-use scenario: abandoned gas stations and auto-repair shops as a source of contamination. 
Figure 9. Land-use scenario: abandoned gas stations and auto-repair shops: phytotypologies to address contaminants.
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     Phyto is a very well written handbook with communicative diagrams and clearly presented tables to bridge the otherwise somewhat obtuse theory and research on phytoremediation with real-life applications for the design praxis and education. As such, Phyto is a real exception compared to current literature on phytoremediation or phytotechnologies. Using this book bypasses time-consuming literature reviews while providing reliable information and guidance. This is relevant because scientific research largely focuses on laboratory experiments and less on multifaceted land-use applications. Another benefit of the book is that it clearly addresses limitations and opportunities for phytotechnologies. The book reinforces the treatment of organic contaminants where phytotechnologies have had positive results. Therefore, interdisciplinary collaboration is suggested throughout for this highly complex yet promising field of applied research toward common practice. Phyto reinforces the idea of using prophylactic measures or rethinking everyday scenarios such as urban and suburban residences, community gardens, or graveyards. New experiences and accomplishments in these areas can help promote phytotechnologies as best management practices.
     While Kennen and Kirkwood identify nonspecialists of phytotypologies as targeted readers, it would be great if the book could also inspire scientists and engineers to reach out to the landscape design profession to explore the aesthetic and cultural potential of phytotechnologies. This is important when related to more fundamental questions of aesthetics, ecology, and sustainability. Such issues have to be addressed if we want landscapes that perform phytotechnologies to be valued and accepted. The book targets the education of landscape architecture and other design fields to become competent experts within the broader context of brownfield redevelopment and the creation of healthy environments. Phyto has the potential to open new chapters in landscape architecture.

S. Rock, cited in Kennen and Kirkwood, Phyto, p. xxv.
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