Buenos Aires project uses plants to absorb pollutants

A team of researchers from the University of Flores [UFLO] in Buenos Aires has begun a small-scale planting project on the bank of the heavily polluted Matanza-Riachuelo river basin that could have long-awaited environmental results.

The river basin, which divides the city of Buenos Aires from Buenos Aires province, is currently considered one of the ten most polluted places in the world.

The initiative – a product of an agreement signed in 2015 by UFLO and the municipal government’s environmental protection unit – aims to treat one of the many contaminated sections of the river bank using a process known as phytoremediation whereby certain plants absorb concentrations of heavy metals in the soil through their roots.

Laura de Cabo, a professor of Biological Sciences at UFLO, explained how specific plants native to the region can soak up the pollutants without getting damaged in the process.

“We are using a technique called phytoremediation in a small-scale format of one hundred linear meters along the coast of the Riachuelo [river] on the side that borders the city of Buenos Aires. It’s an experiment based on the utilization of aquatic plants and native grasses such as reeds, sagittaria [sagittaria montevidensis], floating pennywort [hydrocotyle ranunculoides], which have the capacity to absorb pollutants including heavy metals. We know this because we have done an analysis of the soil on the banks of the Riachuelo. There are heavy metals among other contaminants and these plants can absorb them without dying in the process,” she said.

For decades, factories dumped industrial waste into the river and despite a court-ordered clean-up effort in 2008, environmentalists warn that not enough progress has been made.

While the amount of floating garbage has been dramatically reduced in recent years, high levels of dangerous heavy metals such as arsenic, chromium, copper, zinc and lead have been measured in the river and bank soil.

Exposure to lead and other heavy metals can damage nerves, reproductive systems, and kidneys, especially among children.

At least 20,000 people, many of whom live in slums located on the river banks, live in direct contact with the heavily polluted area.

Ana Maria Faggi, dean of UFLO’s Faculty of Engineering, stressed the importance of using native plant species in the project, as opposed to exotic vegetation.

“What we want to do is help the ecosystem recover with vegetation that is typical of the area and not with exotic vegetation which is what generally used to happen until now. On the other hand, this is going to benefit the fauna because we are going to be able to recover many of the birds that are typical of the forest and it’s also a project with social significance because it has a cultural impact. That is to say, people will once again be able to see the characteristic vegetation on these banks,” she said.

Phytoremediation is cheaper than traditional environmental clean-up methods and allows for the preservation of the original site as opposed to decontamination techniques which involve excavation and the disposal of pollutants elsewhere.


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