Ateneo-led research team discovers fern that absorbs arsenic and copper

September 04, 2019
A research team of Filipino environmental scientists, led by Ateneo de Manila University Assistant Professor Rene Claveria, has achieved a breakthrough in using plants to remove metal contaminants in the soil. 
Pteris melanocaulon, a native fern, was initially determined as a metallophyte—a plant capable of growing in soils even when there’s 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,” Claveria said. “What we discovered much later is that this fern can also accumulate high levels of arsenic.”
Claveria and 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), Ms. Mary Jane Apuan (Xavier University Cagayan de Oro) and Ms. 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.

The research team in an open pit mine in Surigao del Norte.  From left: Ms. Mary Jean Apuan, Ms. Ellaine Rubee Perez, Dr. Dennis Apuan, Dr. Tess Perez and Dr. Rene Claveria.
Dr. Augustine Doronilla, a DOST Balikscientist from the University of Melbourne who also mentored the team, was instrumental in the discovery process. “It was Dr. Doronilla who introduced to us to phytoremediation or using plants to remove and immobilize contaminants in soil and groundwater,” Claveria said. Doronilla, he said, spoke of 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 fern’s ability as an arsenic accumulator.

The copper and arsenic- accumulating fern Pteris melanocaulon thrives very well in abandoned mining areas in Surigao and Cebu.
With funding from DOST-PCIEERD, the team was given access to field surveys and sampling.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. 

The team conducts water and soil quality tests in the abandoned mine areas.
“It is the first type of fern discovered to accumulate copper in the roots and arsenic in the leaves,” Claveria said.

The greenhouse at Xavier University where most of the ferns being studied were propagated and experimented on.
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. Ingesting fish or mollusks that are exposed to arsenic results in arsenic poisoning.

Dr. Augustine Doronila (left) with some members of the research team during one of his field visits to the project sites. 
The new discovery then is useful especially in helping the mining industry and the local government remove, stabilize and destroy contaminants in the soil, said Claveria. “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."
The findings were published in International Scientific Journals:  International Journal of Phytoremediation (2015) and Chemosphere (July, 2019).