Why Bioremediation Is Scarce in Urban Gardens

Bioremediation techniques must face a series of hurdles before being accepted as feasible, large-scale soil contamination solutions.

Earth Repair

"Earth Repair," by Leila Darwish, is essential reading for anyone who wishes to transform environmental despair into constructive action.

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Packed with valuable, firsthand information from visionaries in the field, Earth Repair (New Society Publisher, 2013), by Leila Darwish, empowers communities and individuals to take action and heal contaminated and damaged land. Encompassing everything from remediating and regenerating abandoned city lots for urban farmers and gardeners, to recovering from environmental disasters and industrial catastrophes such as oil spills and nuclear fallout, this fertile toolbox is essential reading for anyone who wishes to transform environmental despair into constructive action. The following excerpt comes from chapter 2, “Earth Repair and Grassroots Bioremediation.” 

You can purchase this book from the Utne store: Earth Repair. 

The urban gardener is in regular physical contact with soil, breathing its dust and eating foods grown from it. Few others have such an intimate relationship with city soils, a resource that is seen by most others as something that only serves as a foundation for buildings and roads. Logically then, gardeners are concerned with soil contamination issues and are looking for simple and low-cost means to address them.

For a number of years now, urban gardeners and their supporting organizations have been aware of the concept of bioremediation. Bioremediation’s use of naturally occurring organisms, apparent affordability and minimal disturbance to soils all add to its attractiveness. The idea of partnering with life-forms such as bacteria, plants, worms and fungi (all of whom gardeners are already familiar with) greatly adds to its appeal. Numerous scientific studies have been conducted that support bioremediation’s effectiveness — there’s no question that given the right circumstances, these organisms have the potential to degrade, immobilize or sequester a variety of contaminants. Bioremediation would appear to be an ideal and elegant solution to issues of soil toxicity. Why then, have bioremediation techniques not yet been put into use broadly as a means to remediate contaminated soils in urban gardens? Why are we not seeing citizen groups applying the tools of bioremediation and publishing their results?

These are questions that I have been asking for a number of years in my work designing ecologically and socially regenerative systems in urban environments. In 2004, the Rhizome Collective, an organization that I co-founded in Austin, Texas, received a $200,000 grant from the US Environmental Protection Agency to clean up a brownfield site located in the city. This cleanup primarily involved removal of tons of trash and debris — a twisted mountain of concrete, rebar, wood scraps, tires and carpet scraps — from a former illegal dumping site. Although levels of organic and heavy metal pollutants on the site met residential standards, concerns remained about the safety of gardening there, post-cleanup.

Unfortunately, funding in the grant would not cover the cost of soil remediation. Shortly afterwards, I was part of an effort to establish a community-based bioremediation plan in post-Katrina New Orleans to help address residual hydrocarbon contamination left behind from the storm. Compost teas were applied to areas known to be affected by pollutants. While the program received donations of services from soil testing labs, the funds were insufficient to carry out a properly managed remediation program on the scale that was necessary.

The barriers to community-based bioremediation are many. One such obstacle is that there is still a great deal of mystique, particularly to the less scientifically literate, surrounding bioremediation and its processes. This lack of understanding can make bioremediation an intimidating prospect to many. The vast majority of literature concerning bioremediation exists in scientific journals, written in a dry academic style that is close to unreadable by the layperson. The bulk of these studies are conducted in highly controlled, sterile laboratory conditions, incredibly different from the diverse, heterogeneous and competitive ecologies that exist in a garden environment.

In order for this boundary to be spanned, a few individuals that are scientifically literate will need to wade through the journals and distill a series of guiding principles and best practices usable by the average gardener. From there, a push needs to made from within and outside of academic institutions to conduct a greater number of field-based trials, where proven bioremediation techniques are put to the test in real-world conditions. Emphasis needs to be placed on techniques that are simple, affordable and that make use of commonly available biological agents. The focus of these studies should be on the top 12 inches of soil, the zone in which the majority of urban gardeners are active. Partnerships between citizen groups and academic institutions are vital, as universities have access to technological resources that gardeners are commonly lacking but are necessary to conduct such trials.

Cost is another significant barrier to implementing bioremediation techniques. While bioremediation is relatively inexpensive, especially when compared to more intensive means of conventional remediation, its use still requires some expenses, particularly when soil testing is involved.

For example, spreading spent mushroom substrate over an oil spill could conceivably be done for little or no cost. Testing the contaminated soil, however, to be sure that the total petroleum hydrocarbons have been reduced to safe levels can be prohibitively expensive — potentially hundreds or thousands of dollars. While the spent substrate application may have been successful in degrading the oil, without verifiable data to prove its effectiveness it is difficult to get the support needed to replicate the process on a broad scale.

Governmental agencies ideally would play a role in funding citizen-based cleanups, although they have done very little to date. Most of the government funds that exist for brownfield remediation go to large-scale developers, who are primarily interested in meeting regulatory obligations as quickly as possible. These developers typically favor a “dig and dump” approach to soil remediation, rather than dealing with the longer time scale and other uncertainties that can accompany bioremediation.

Additionally, many governmental agencies charged with environmental protection are reluctant to work with citizen groups, fearing liability were something to go wrong. Consequently, governmental agencies are commonly unfamiliar with small-scale bioremediation. It is my belief that it is very much in the interest of government agencies to alter this policy. As interest in community gardening increases, so will the number of people wanting to partake in soil remediation. These people are going to attempt remediation, whether or not they receive assistance from agencies. Therefore, it makes sense for agencies to offer some form of guidance or assistance so that people do not put themselves in harm’s way.

Part of this work would be developing a solid method of risk analysis for exposure to soil toxins. Currently, no such framework exists. It is important to be able to answer important questions like “what is the danger of being exposed to a particular contaminant in the soil, and further, what is the danger of that being taken up into a plant and being passed into my body?” These aspects of risk need to be weighed against all the benefits of gardening, such as improved nutrition, physical exercise and enhanced community relationships. Developing such a framework is a multi-disciplinary task, involving the fields of ecology, toxicology, public health and medicine.

Developing a protocol for qualitative soil analysis is another innovation that could reduce the cost of bioremediation. It may be possible to create a method for assessing the quality of soils using what are called bioassays. An example of a bioassay would be testing seed germination rates in soils with known levels of toxicity. Using this information, it could be possible to determine contaminant levels in soils using only plant seeds, potentially cutting the cost of soil testing dramatically.

Bioremediation holds great promise for urban gardeners as a tool for achieving improved soil health. Hopefully, in time and with the cooperation of institutional entities, it can go from being an experimental technique to a broadly utilized strategy.

Scott Kellogg is the educational director of the Radix Ecological Sustainability Center in Albany, New York and author of the book Toolbox for Sustainable City Living. He has recently completed a Masters degree in Environmental Science from Johns Hopkins University, where he wrote his thesis on the topic of low-intensity, community-based bioremediation techniques. 

This excerpt has been reprinted with the permission of Earth Repair: A Grassroots Guide to Healing Toxic and Damaged Landscapes by Leila Darwish and published by New Society Publishers, 2013. Buy this book from our store: Earth Repair.