An Ateneo de Manila University (AdMU)-led research team of environmental scientists has achieved a breakthrough in using plants to remove metal contaminants in the soil.
The team, led by AdMU Assistant Professor Rene Claveria, discovered that a fern could absorb copper and arsenic—two metal contaminants common in mining sites, an AdMU news release said.
Pteris melanocaulon, a native fern, was initially determined as a metallophyte—a plant capable of growing in soils even when there is a high concentration of metals.
“In a copper-gold mining area as study site, the fern was discovered to have an ability to accumulate copper,” said AdMU Assistant Professor Rene Claveria. “What we discovered much later is that this fern can also accumulate high levels of arsenic.”
Claveria and the members of his team—Dr. Teresita Perez (Ateneo de Manila University), Dr. Dennis Apuan (University of Science and Technology of Southern Philippines-Cagayan de Oro), Mary Jane Apuan (Xavier University Cagayan de Oro) and Ellaine Castillo Perez (Institute of Biology, University of the Philippines)—observed the fern’s ability to tolerate toxic levels of arsenic in mining areas in Surigao and Cebu.
Dr. Augustine Doronilla, a Department of Science and Technology “Balik Scientist” from the University of Melbourne who mentored the team, was instrumental in the discovery process.
“It was Dr. Doronilla who introduced us to phytoremediation or using plants to remove and immobilize contaminants in soil and groundwater,” Claveria said.
Doronilla, he said, spoke of the fern’s ability as an accumulator.
In 2014, the research team found Pteris melanocaulon to be an efficient copper accumulator. Hoping to dig deeper into the plant’s tolerance to toxic compounds, Claveria and his team sought to assess the fern’s ability as an arsenic accumulator.
With funding from DOST-Philippine Council for Industry, Energy, and Emerging Technology Research and Development, the team was given access to field surveys and sampling, the news release said.
They found that Pteris melanocaulon was able to grow in soils that were contaminated with copper and other elements, such as arsenic.
These observations were confirmed on potted experiments, where different concentrations of copper and arsenic solutions were made as soil amendments. Findings show that the fern’s roots and leaves were not affected.
“It is the first type of fern discovered to accumulate copper in the roots and arsenic in the leaves,” Claveria said.
Arsenic is a toxic metalloid that naturally occurs in some copper and gold mining projects and gets exposed during open-pit mining, contaminating the soil and water in the process.
Excessive levels of arsenic may cause major health complications—from skin damage to problems in the circulatory system and even cancer.
Arsenic exposure in waterways like streams and rivers may lead to contamination of the living organisms in such ecosystems.
Eating fish or mollusks that are exposed to arsenic results in arsenic poisoning.
The new discovery then is useful especially in helping the mining industry and the local government remove, stabilize and destroy contaminants in the soil, Claveria said.
“Successful propagation of Pteris melanocaulon can clean up the entire area, making it suitable for other plants to grow. This can help revegetate and stabilize the land that is already affected by toxic elements,” Claveria was quoted in the AdMU news release.
The findings were published in international scientific journals, such as International Journal of Phytoremediation (2015) and Chemosphere (July 2019).