How can plants clean contaminated soils?
[[{“value”:”
How can plants clean contaminated soils?
Soil contamination is a global issue. Human activities cause toxic chemicals, heavy metals and salts to seep into soils, damaging natural ecosystems and reducing the productivity of agricultural land. Cleaning contaminated soils is not easy, but Professor Barbara Zeeb, an environmental scientist at the Royal Military College of Canada, believes plants can provide the solution. She is investigating how plants can remove the salts that contaminate roadside ecosystems.
Talk like an environmental scientist
Accumulator halophyte — a halophyte that stores salt in its tissue
Endophyte — a microbe (e.g., bacterium or fungus) that lives inside a plant without damaging it
Halophyte — a plant adapted to growing in saline environments
Phytoremediation — the use of plants in remediation, usually to remove contaminants from an environment
Recretorhalophyte — a halophyte that excretes salt through its leaves
Remediation — the process of fixing environmental damage
Saline — salty
Adding salt to roads in winter is a simple way to make driving safer. Salt lowers the freezing point of water, making ice less likely to form thereby reducing the chances of road accidents. However, while road salt is hugely important for improving safety, it has a hidden environmental cost. Common salt (sodium chloride; NaCl) might seem harmless, but high concentrations of salt can be catastrophic for natural ecosystems.
Why is salt a problem?
“Canada has the world’s highest per capita use of road salt,” says Professor Barbara Zeeb, an environmental scientist at the Royal Military College of Canada. Throughout the winter, road salt accumulates along Canadian roadsides. “As temperatures rise in spring, snowmelt carries this salt into nearby ecosystems,” she explains. “There, the salt disrupts the soil’s structure and chemistry. As most plants can’t tolerate high salt concentrations, the excess salt in the environment kills them or stops them from being able to reproduce.”
This loss of plant matter then in turn impacts the entire ecosystem. As ecosystems lose organic matter and the organisms that recycle it, the carbon stored within these environments is also lost, contributing to climate change and decreasing the land’s fertility. “On average, saline soils have lost 3.47 tonnes of carbon per hectare,” says Barbara.
How can plants reduce salt contamination?
Thankfully, the solution to salt contamination may be right in front of us. “Living plants can extract, stabilise or degrade harmful compounds within soils, sediments and water,” explains Barbara. Phytoremediation is the technique of using plants to clean up contaminated sites. “Phytoremediation is a cost-effective technology that can address many different contaminants, including metals, hydrocarbons, pesticides and salts.” It uses the natural processes of certain plant species to clean soils, providing a sustainable and environmentally friendly means of decontamination. “Phytoremediation is economical because plants do most of the work, so equipment and labour costs are relatively low,” says Barbara. In addition, adding or encouraging the growth of native plants to ecosystems increases biodiversity.
While most plants cannot tolerate saline conditions, some – known as halophytes – thrive in them. Barbara is exploring how halophytes can be used to remove salt from contaminated soils. “There are two types of halophytes useful for phytoremediation: accumulator halophytes and recretohalophytes,” says Barbara. “Both take up salt from the soil through their roots. Accumulator halophytes store the salt in their tissues, while recretohalophytes excrete excess salts through glands on their leaves.”
How does Barbara study halophytes?
Barbara and her team carry out field studies to examine the effectiveness of halophytes at reducing salt contamination, both along roadsides and at industrial salt-contaminated sites. “We set up plots using a variety of native halophyte species,” she explains. The team monitors the plants’ growth and health, then harvests them at the end of the growing season. “We analyse plant and soil samples in our laboratory to determine how much salt has travelled from the soil into the plant tissues,” says Barbara. “We can use this information to calculate approximate remediation timelines for the soils.” As recretohalophytes excrete salt from their leaves, Barbara is interested in where the wind disperses this salt. The team takes air samples from around the field sites to monitor the amount of salt in the air. “These samples enable us to model salt dispersal and build deposition maps,” says Barbara.
What has Barbara discovered?
Reference
https://doi.org/10.33424/FUTURUM616
The team’s initial findings suggest that both accumulator halophytes and recretohalophytes are highly effective at remediating saline soils. “Our calculations indicate that native accumulator halophytes could remediate some salt-contaminated soils in less than three years,” says Barbara. “Given that contamination usually happens over many years, even decades, this is remarkable.” The team also found that harvested accumulator halophyte plant matter can be processed to remove chloride ions and then used as compost, providing an added benefit.
The recretohalophytes removed very high quantities of salt from contaminated soils and the team’s dispersal models show that these salts were widely dispersed and deposited in low concentrations. “This is good news!” says Barbara. “At low levels, salt ions act as essential nutrients for organisms, rather than toxic contaminants.”
What next for Barbara’s research?
“In my greenhouse and growth chamber, we are carrying out exciting new studies to identify halophytic endophytes,” says Barbara. Endophytes are microbes which live within plants, and Barbara is interested in plant growth promoting bacteria which live endophytically within halophytes. “As the name suggests, these promote plant growth, while also reducing plant stress and, in some cases, inhibiting plant pathogens,” she explains.
The team uses molecular methods to identify endophytes, by isolating and sequencing the bacterial DNA found in halophytes. “Our goal is to identify the endophytic communities of the best performing accumulator halophytes and recretohalophytes,” says Barbara. “We will then carry out further studies to determine their effects on plant productivity and their ability to assist with salt extraction.”
Barbara’s research is highlighting the importance of using native plants to restore ecosystems that have been damaged by human activity. Her findings have the potential to usher in a new generation of efficient, sustainable and environmentally friendly soil remediation methods, and her work with endophytes is leading phytoremediation in a new and exciting direction.
“I hope that our research will encourage government agencies to adopt phytoremediation and incorporate this important technology into more site remediation plans,” says Barbara. “As my students graduate and go off to work in environmental consulting firms, I am hopeful that the merits of phytoremediation will become more well-known and widespread.”
Professor Barbara Zeeb
Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Canada
Fields of research: Environmental science, phytoremediation
Research project: Investigating how salt-tolerant plants can remove salts from contaminated soils
Funders: Natural Sciences and Engineering Research Council of Canada (NSERC), Toronto and Region Conservation Authority (TRCA), Imperial Oil, Ontario Ministry of Transportation (MTO), Partners in Project Green
About environmental science
Environmental science is the interdisciplinary study of the environment. By combining knowledge from a range of fields, including biology, chemistry, geography and engineering, environmental scientists seek to understand and address environmental issues.
What are the applications of phytoremediation?
Phytoremediation is not only used to remove salts from soils. It can also clean water, waste sludge and air. It is an effective and versatile decontamination technique but has only recently become widely used. “When I began working on phytoremediation, most people didn’t believe plants could be used for remediation of industrial contaminants,” says Barbara.
Barbara has previously investigated whether plants can remove polychlorinated biphenyls (PCBs) from soils. PCBs are highly toxic carcinogenic chemicals that were commonly used in industrial products. Although they are now banned, they still persist in the environment. She has also used plants to successfully remove nickel, zinc and cadmium from military bases. “I believe that although phytoremediation is rarely a solution on its own, it has a role to play in almost every site clean-up,” she says.
What is the future of environmental science?
As environmental issues mount up around the world, so do the challenges facing the next generation of environmental scientists. “Climate change mitigation and adaptation, pollution control and waste management, and sustainable resource management all demand technical expertise and innovative thinking,” says Barbara. “Phytotechnologies will play an important role in all these areas, as we need to focus on moving towards green, nature-based solutions to environmental challenges.”
“Environmental science is an exciting area to pursue as you will get to make a real difference in the world,” says Barbara. “What could be more satisfying than restoring a contaminated site to one that is safe and aesthetically improved?”
Pathway from school to environmental science
At school and beyond, gain a solid background in biology, chemistry and physics, while also honing your written and verbal communication skills.
There are many paths to a career in environmental science. At university, a degree in environmental science, environmental engineering, environmental chemistry, biology, ecology or physical geography will provide you with skills and knowledge that you can apply to address environmental challenges.
While Barbara is now an environmental scientist who does environmental engineering work, she is a biologist by training. “I started my research career studying dead algae from the bottom of lakes, and moved on to phytoremediation from there,” she says. “I think this speaks to the ability of all of us to pivot at different times in our careers to address the issues that interest us the most.”
Explore careers in environmental science
Many careers in environmental science are focused on sustainability, conservation and protecting the natural world. For example, environmental engineers protect and restore the environment by managing and reducing waste and cleaning up contaminated ecosystems, while environmental consultants provide expert advice and solutions to environmental issues, including land and water remediation.
Prospects provides information about careers in environmental science, including the qualifications you need and the salary you can expect: www.prospects.ac.uk/careers-advice/what-can-i-do-with-my-degree/environmental-science
Barbara is President of the International Phytoremediation Society, an organisation focused on developing phytotechnologies. Learn about the society’s resources, projects and networking opportunities: www.phytosociety.org
Meet Barbara
I have always enjoyed spending time in nature. As a teenager, I enjoyed camping in Algonquin Park, Ontario, with my friends. And in high school, field trips out of the classroom were a highlight for me.
I have worked at several former military stations across the Canadian Arctic and northern Ontario. These locations were remote and beautiful, but the activities that occurred there led to contamination of the land. I was initially employed to assess contamination at these sites, but over time, I had the opportunity to get involved with remediation activities.
I advocate for phytoremediation because it helps clean up sites and contributes to returning ecosystems to their former state. Phytoremediation creates new habitats, increases biodiversity and captures carbon while simultaneously removing contaminants from a site.
We are facing so many environmental challenges these days. It’s rewarding to know that I play a small part in cleaning up the contaminants caused by human activities, through a green, nature-based solution.
I love that I can work with native plant species and that my remediation projects are adding more plants to ecosystems. I particularly enjoy working with halophytes as they have such unique physiological adaptations for dealing with saline soils and water. Some can also degrade organic contaminants, so my goal is to find a plant that can simultaneously degrade petroleum hydrocarbons while efficiently extracting, secreting and dispersing salt ions.
I was introduced to the joys of independent research by my terrific PhD supervisor, Professor John Smol. Now, I love mentoring my students and teaching them how to approach and solve environmental issues. Their fresh ideas and outlooks give me the energy to keep doing this work!
Barbara’s top tip
Study what interests you most, but don’t be afraid to change direction in your studies or career if your interests change. Keeping things fresh is what keeps us interested and motivated to learn new things every day.
Do you have a question for Barbara?
Write it in the comments box below and Barbara will get back to you. (Remember, researchers are very busy people, so you may have to wait a few days.)
Discover how chemical pollutants can impact animal health:
futurumcareers.com/the-hidden-chemicals-affecting-primates-hormones
The post How can plants clean contaminated soils? appeared first on Futurum.
“}]]