Bioremediation: Absorbing the Damage of
Disasters
Written by: Molly Fendrick
Written on: June 12, 2014
As society develops, the pollution it creates becomes more and more hazardous.
To protect people from these contaminants, scientists are constantly developing
new ways to remediate contaminants. Bioremediation, the application of living
organisms to remove environmental pollutants, holds incredible potential as a
solution to environmental pollution and has even been successfully used to clean
up nuclear catastrophes.
Introduction
If left untouched, the thousands of acres surrounding Chernobyl will be unsafe to
grow crops on for the next 20,000 years [1]. Almost 30 years ago, over 350,000
people were permanently evacuated from the town of Chernobyl when a reactor
at the nuclear power plant exploded and sent a radioactive veil across Ukraine,
Turkey, and Belarus [1]. The explosion at Chernobyl is considered to be the
worst nuclear catastrophe in history. Nothing like it had ever happened before,
so scientists and engineers scrambled to come up with methods to clean up the
harmful radiation. Through bioremediation, the utilization of living organisms to
remove environmental pollutants, radioactive contamination worldwide has been
significantly remedied. In 2011, a nuclear reactor in Fukushima melted down,
causing Japan to be severely damaged in the same way that Ukraine had been
only 25 years before [1]. Once again, the cleanup process began, but this time
they had Chernobyl to look to for guidance. Bioremediation was implemented at
Fukushima, and so far has been successful in remediating the site. Learning
from disasters such as these, many cities in the United States are now utilizing
bioremediation techniques to clean up all types of pollution, radioactive or not, in
the air, water, and soil [1].
A History of Nuclear Disasters
When Chernobyl’s reactor exploded in Ukraine in 1986, it shocked the world.
While there had been issues and small tragedies from nuclear power before, the
world had never seen anything on a scale as great as Chernobyl. The estimated
number of human cancer deaths directly caused by Chernobyl is as high as
27,000 [1]. Engineers and scientists are still working to study the effects that
Chernobyl has had on the surrounding life. While many species of plants and
animals have moved into the uninhabitable zone, as seen in Figure 1, there are
also mutations present in the organisms that have moved into this area [2]. A
major concern of these scientists is that the mutations in the region surrounding
Chernobyl will migrate out of the affected area and into the general population
[2]. There is no way of knowing for sure what Chernobyl’s long-term effects will
be like, because it was the first nuclear explosion of such large magnitude.
Similar accidents since then have had the slight advantage of being able to look
to and learn from the cleanup at Chernobyl.
Figure 1. A wolf within the uninhabitable area surrounding Chernobyl [3]
More recently, in Fukushima, Japan, several reactor cores at a nuclear power
plant partially melted in March 2011 when they were damaged by an earthquake
and the subsequent tsunami [4]. Not only did this cause over 160,000 residents
to be removed from the area, but it also constituted the largest discharge of
radioactive material into the ocean in history. Areas surrounding the power plant
are now unable to sell agricultural crops, and fishing is not allowed within the
waters adjacent to the meltdown, completely devastating the productivity of this
area [4]. The people of Japan, as well as the rest of the world, will be recovering
from such a devastating accident for centuries to come. They look to the cleanup
of Chernobyl to understand what the lasting effects will be, but it can be difficult
to predict what radioactive sites will look like in the future. In the United States,
Bikini Atoll is still uninhabitable, 70 years after nuclear testing was done there [5].
Watching the effects of radiation on animals can help show how humans may be
affected in the long run, but because most animals live shorter lives than
humans, it takes longer to see how the radiation from such disasters affects
humans genetically [6]. The effects of these tragedies will be evident for
centuries, left for future generations to continue to manage.
Cleaning up a radioactive site is not just one that includes the immediate
responders. For generations, the people of these areas will be tasked with
cleaning up and containing the radioactive pollutants as well as the structures
that housed them. The main contaminant released by nuclear accidents,
radioactive cesium, has a half-life of 30 years [4]. All radioactive contaminants
take about 10 half-lives to disappear enough for an area to be considered safe
[4]. Nearly 2 million acres of land around Chernobyl has been permanently
damaged by radiation [7]. In Fukushima, thousands of acres have been infected
with radiation, and it is continually being spread by melting snow and rainwater
[4]. Scientists are rushing to diminish the levels of contamination in these
expanses to minimize the spread of radiation to the rest of the world.
Recovering Chernobyl and Fukushima
In order to minimize contamination in radioactive disaster zones, many different
methods of cleanup have been engineered to remove radionuclides as quickly as
possible. Bioremediation, the application of living organisms to remove
environmental pollutants, has proven to be a quick, inexpensive, and efficient
method of removing radioactive pollutants [8]. There are two common types of
bioremediation currently utilized: phytoremediation, the use of plants to clean up
radionuclides, and mycoremediation, the use of fungi. Bacteria can also be used
to remediate pollutants, although their use has not yet been documented at any
large nuclear disaster sites [8]. Phytoremediation, as graphically shown in Figure
2, has been well documented as a useful method for decontaminating the land
and water around Chernobyl. Plants such as sunflowers and Indian mustard
have been planted there, and eagerly absorb cesium and strontium, pulling it out
of the ground and into their stalks and leaves [10]. These two elements have
radioactive isotopes which are emitted by nuclear reactors, and when they are
released into the environment they often lead to cancer in humans and animals.
The removal of these isotopes is important in minimizing the amount of time that
an area is uninhabitable after a nuclear disaster. Mycoremediation through the
use of mushrooms has also proven to be a quick method of removing
radionuclides, especially cesium, and it has been proposed as a method of
cleaning up Fukushima. Once these plants and fungi have absorbed the
radionuclides, they are removed and incinerated, and replaced with new plants
that will continue to soak up radiation from the ground [10].
Figure 2. A simplified illustration of phytoremediation [9]
At Chernobyl, sunflowers were planted onto rafts, allowing their roots to hang
down, and placed into contaminated water [11]. They were able to successfully
soak up nearly all of the radioactive cesium in the water in about three weeks. In
the three years since Fukushima’s explosion, people have begun to plant
sunflowers in hopes that it will reduce the radioactivity levels in a similar way, as
seen in Figure 3. [11]. It is not a perfect system, as the reach of these organisms
is limited to the top few inches of the soil, and there are still harmful ashes to deal
with after incineration of the radioactive plants. But it is still a much better option
than leaving the radionuclides in the environment, and the hazardous ash is
easily and safely stored away below ground [6]. Bioremediation continues to be
refined and improved for use at these enormous accident sites, but has also
proven useful for cleaning up numerous other types of contaminants at a variety
of sites.
Figure 3. Sunflowers planted at Fukushima [12]
Remediation in the United States
Across the globe from these tragedies, a dry cleaning plant in Houston is
adopting the strategies used at nuclear contamination sites to remove harmful
pollutants from the ground below [13]. By implementing bioremediation through
bacteria, the chlorinated solvent concentrations in the groundwater beneath the
business were reduced by 99 percent in less than 90 days. By law, dry cleaners
in California will stop being allowed to produce chlorinated solvents within the
next decade [13]. Even when they do stop producing these pollutants, there will
still be all of the previous build up of harmful contaminants below these buildings.
These chlorinated solvents are known carcinogens, and need to be removed
from the soil as quickly as possible [13]. As seen at the Houston site,
bioremediation is the quickest and easiest method of doing so, and can be
applied to a wide range of locations.
Even though the United States has not had a large-scale nuclear disaster, it still
has the need to clean up nuclear waste. Hanford, located in Washington State, is
the nation’s largest site of nuclear pollution [14]. For decades, plutonium for
nuclear weapons was processed here. The factory has closed, but the
government is now tasked with cleaning up the leftover radioactive waste. This
waste is stored in 177 underground tanks, shown during construction in Figure 4.
Some of these tanks are currently leaking, although fortunately it is a very lowactivity nuclear waste when compared to areas like Fukushima and Chernobyl.
As federal negotiations and plans for cleaning up this site are developed,
bioremediation is becoming considered as a leading option for removing the
waste from the soils and groundwater [14].
Figure 4. The storage tanks at the Hanford Nuclear Reservation in Washington State [15]
Of all of the nuclear power plants in the United States, Indian Point is thought to
be the one at maximum risk of severe earthquake damage, similar to Fukushima
[16]. Located 25 miles north of New York City, there has always been concern
from the public about the safety of the plant. If it were to malfunction, 20 million
people could potentially be displaced [16]. After the disaster at Fukushima, this
plant, along with the 64 other nuclear power plants in the United States, has
increased safety guidelines and inspections on reactors in order to maintain the
safest functionality and prevent anything from malfunctioning [16].
The Future
There is no way of knowing for sure how time will change the uninhabitable
zones around Chernobyl and Fukushima, but as research and funding for
bioremediation grows, it is at least known for certain that these organisms will
continue to reduce the amount of radioactivity in these zones. Large-scale
nuclear disasters will require cleanup for tens of thousands of years, and as we
create new ways of remediating these areas, we will be able to scale these
technologies down and apply them to an array of polluted sites across the globe.
References
[1] E. Harrell and J. Marson. (2011, Apr. 16). “Apocalypse Today: Visiting
Chernobyl, 25 Years Later” [Online]. Available: www.time.com
[2] K. Ravilious. (2006, Apr. 26). “Despite Mutations, Chernobyl Wildlife is
Thriving” [Online]. Available: www.news.nationalgeographic.com
[3] L. Helmuth. “Chernobyl’s Wildlife Survivors” [Online]. Available:
www.slate.com
[4] S. Starr. (2012). “Costs and Consequences of the Fukushima Daiichi
Disaster” [Online]. Available: www.psr.org
[5] “Conditions at Bikini Atoll” [Online]. (2013, Sep. 9). Available: www.ns.iaea.org
[6] “Chernobyl and Fukushima Radiation Reduces Animal and Plant Numbers,
Diversity, Lifespan, Fertility, Brain Size, Increases Deformities and Abnormalities”
[Online]. (2014, Mar. 13). Available: www.globalresearch.ca
[7] R. Maughan. (2013, Dec. 31). “Chernobyl Nuclear Disaster Site Becomes a
Wildlife Area, including over a hundred wolves” [Online]. Available:
www.thewildlifenews.com
[8] I. Rakin, R.D. Smith, D.E. Salt. (1997). “Phytoremediation of Metals: Using
Plants to Remove Pollutants from the Environment” [Online]. Available:
www.ufv.br
[9] P. Favas, J. Pratas, M. Varun, R. D’Souza, and M. Paul. (2014, Mar. 26).
“Phytoremediation of Soils Contaminated with Metals and Metalloids at Mining
Areas: Potential of Native Flora” [Online]. M. Hernandez Soriano, Ed. Available:
www.intechopen.com/books
[10] “Bioremediation for Contaminated Soil: Phytoremediation and
Mycoremediation” [Online]. (2011, Jul. 16). Available:
www.holisticradioprotection.wordpress.com
[11] http://www.helladelicious.com/diy/2011/09/sunflowers-and-bacteria-clean-upradiation/
[12] S. McFadden. (2011, Jul. 21). “Sowing Seeds of Hope at Nuclear Disaster
Site” [Online]. Available: www.thecalloftheland.wordpress.com
[13] “Bioremediation Saves Dry Cleaners Hundreds of Thousands of Dollars”
[Online]. (2014, Jan. 8). Available: www.environmentalleader.com
[14] “Cleanup Plan for Hanford Nuclear Reservation Pushed by Frustrated
Washington State Leaders” [Online]. (2014, Mar. 31). Available:
www.oregonlive.com
[15] “Leaking Underground Tanks at Hanford” [Online]. Available:
www.ecy.wa.gov
[16] W. Dizard. (2013, Oct. 14). “Fukushima on the Hudson: Could a Nuclear
Accident Happen Near NYC?” [Online]. Available: www.fairewinds.org