We’ve done much damage to our planet. We’ve cut down trees. We’ve used pesticide and fertilizer chemicals on our soil and plants. The good news is this: the planet was designed to heal itself. To first begin, we need to help. I believe we can use bioremediation to fix some of the environmental problems we have created and as a preventative mediation for future issues.
Cornell University describes bioremediation as the act of using biological organisms to solve environmental problems (http://ei.cornell.edu/biodeg/bioremed/ ). These organisms run the gamut of species. We’re talking about bacteria, fungi, protists, plants, animals, fish, etc. By placing the right organisms in the right conditions, each and every thing benefits. For example, legumes tolerate a high nitrogen environment as nitrogen fixers. Other plants cannot survive in soils with high nitrogen and will ‘burn’ (shrivel and die), not produce fruits, or turn yellow and drop their leaves. Minerals, moisture, acidity, consistency, and type of soil are some of the variations of conditions that plants require for survival. We can use these needs to solve environmental problems.
So what research has been done? Some of our very own researchers here at The University of Akron discovered some of the ways in which bioremediation can clean up the messes we’ve made. Dr. Teresa Cutright has made some significant discoveries of the ways plants can be used to clean up the water and soil of abandoned mined areas. Acid mine drainage (AMD) is known to contain elements such as excessive aluminum, manganese, magnesium, iron, and other toxic metalloids (Cutright, et al. 2012). While studying an area with AMD, the researchers noticed certain plants succeeding: Phragmites australis, Typha latifolia, Solidago spp., and Glycine max. In this region, Phragmites australis is a known invasive species, so it is no surprise that it was the dominant plant, interspersed with smaller patches of goldenrod, cattails, and soybeans.
Plant biomass (roots, stems, leaves, and flowers), soil, and water samples from each site were collected, prepared, and assessed. For plants to be considered accumulators*, they must have a translocation factor*** greater than one. While some of the plants are more efficient than others at storing particular contaminants, all four of the studied plants are accumulators of aluminum and magnesium. Manganese is accumulated by Phragmites, cattail and goldenrod. Iron is accumulated by Phragmites and goldenrod. Interestingly, Phragmites australis and Typha latifolia at this site reached hyperaccumulator* levels for absorption of aluminum in the shoots**.
*Accumulator < Hyperaccumulator sequestration levels in biomass.
**Shoots are defined as leaves, stems, and flower parts; void of roots
*** The translocation factor is the concentration of the metal in the shoots divided by the concentration of the metal in the roots.
Bioremediation is an important and relevant tool to solving nature’s problems using nature. This strategy is known as a form of biomimicry. The previously described study demonstrates one way in which plants can be utilized: to accumulate the metallic contaminants of acid mine drainage. However, with all solutions, contraindications must also be assessed. One such contraindication is the labeling of Phragmites australis as an invasive species (in Northeast Ohio, et al.). Once planted as an ornamental reed for landscaping, it has taken over many roadsides, wetlands, and other areas. Many park districts have it on their lists of species to eradicate. However, recent ecologists have noticed that the common reed is growing in areas where other species cannot survive. Roadsides in northeast Ohio are laden with ice-melting road salt and other toxic run-off. The decision to consider an invasive species to repair damaged areas is being heavily weighed to assess the benefits and tribulations.
There has been mention of what happens when the plants die. Are these metals just being stored temporarily, giving the appearance of an improvement to the soil only for a short time period? While this is debated currently, I would suggest that this is not always the case. For example, some plants “fix” compounds. A legume converts “bad” nitrogen (N2) into a more organic, usable form (NH3). Some metals are used for photosynthesis, such as iron and magnesium and are commonly found inside plants like Phragmites australis. A perineal plant, it will constantly reseed itself, allowing the metal cycling to be a continual process. Another thought is that the plants could be harvested and moved to areas with low concentrations. The decomposition would put the needed nutrients back into the anemic soil.
I would like to leave with the thought of using bioremediation as a preventative measure. Particularly considering fracked areas and the land that will host the Nexus Pipeline. I do not believe that public opinion will be swayed away from oil to more earth-friendly “fuels.” Even if enforcements are placed, it may be some time before changes are made. During this time, why not consider putting plants and/or bacteria that are specific for combating possible contaminants in these areas? Let’s focus some research on which organisms can successfully combat a wastewater spill, an oil spill, a gas leak, etc. Place these organisms preventatively so no time is lost. Likely it isn’t the end solution, but it is at least a start!
Cutright, Teresa J., Senko, John, Sivaram, Sushil, and York, Matt. 2012. Evaluation of phytoextraction potential at an acid-mine-drainage-impacted site. Soil and Sediment Contamination. 21: 970-984.