Aquatic plants can eliminate pollution by iron -clad tails, studies show

Aquatic plants can eliminate pollution of the estuary by iron ore tails, studies show.

A view of the island inhabited by Typha dongensis after the flow of iron -clad tails. The photo was taken at low tide in August 2019. Courtesy: Hermano Melo Queiroz

Brazilian researchers have analyzed methods used to ferment estuarine plants with iron, and have used their findings to promote an efficient phytoremediation technology for remediation of water and soil contaminated by environmental disasters such as the collapse of the Fundão iron mine tailings dam in Mariana, Minas. State of Gerais (Southeast Brazil). An article about the study was published in Personal Journal.

Researchers believe that Typha dongensis, a reed commonly known as Southern cattail, may be effective in reducing mining waste in the natural environment.

They led operations in Regência in the state of Espírito Santo, at the mouth of the river Doce near the border with Minas Gerais. The area is occupied by about 50 million cubic meters (m3) of the tails that were released when the wall exploded, the worst environmental disaster in Brazilian history. They analyzed the role of T. domingensis (an average of about 2.5 m tall and has coffee flower buds) and Hibiscus tuliaceus (often called beach hibiscus, a 4-10 m tree with flowers. yellow) in the biogeochemistry of iron and their. it can include phytoremediation, the use of living plants to clean soil, air, and water.

Forty -one cities in Minas Gerais and Espírito Santo were affected when the wall exploded on November 5, 2015, killing 19 people. The poisonous waste is estimated to have polluted 240.8 acres of Atlantic Rainforest and killed 14 metric tons of fish. Many programs and initiatives have been started since then to try to reduce the risk.

“Our research concluded that T. domingensis was better than H. tuliaceus because it had more acidification of its root system, and also because iron was accumulated in the cells. “This is important information for future phytoremediation projects,” said Tiago Osório Ferreira, the article’s last author. Ferreira is a professor in the Department of Soil Science at the University of São Paulo’s Luiz de Queiroz College of Agriculture (ESALQ-USP).

“The collection of iron by T. Domingensis and its ability to regulate is good news. In addition to the increase in iron in the air surfaces and ease of care, H is much better. tuliaceus because it grows fast, ”Prof. Ferreira told Agência FAPESP.

The company above all else in its research, he said, because of the connection that has been made between soil geochemistry and biology with similar results, focusing on iron and other materials. such as nickel, chrome, copper and lead, can be the source of the environment. pollution even at low temperatures.

It is high in iron and is an important nutrient for plants. It cannot be detected as a contaminant, but in low -oxygen soils, such as in the estuary, microorganisms can use natural materials and iron to obtain nutrients. energy in the process of dissolving oxygen and releasing toxins. In this way, pollutants can enter water, soil, plants and animals, affect ecosystems and become an environmental hazard.

The iron collection

To adapt to an environment, a plant needs to oxygenate its basic system, responsible for retaining and absorbing water and mineral salts. It works by taking in oxygen from the air through its airway and transferring it to the roots through a porous tissue called the aerenchyma. When oxygen is combined with iron, it melts and forms an iron barrier at the roots, forming a barrier.

T. Domingensis has a large system of roots and aerenchyma, so it has a lot of oxygenation and iron deficiency. The researchers measured 3,874 milligrams of iron per kilogram of dry matter in the plant, up to ten times more than that of H. tuliaceus.

“On our first work trip to the Doce River, in 2015, there were islands with no vegetation and a lot of sand. The cattails were growing a lot,” Ferreira said, adding. Found that the researchers had studied at this place for six years.

He recalled that the Group for Studies and Research on Soil Geochemistry at ESALQ-USP had published other studies in the area, citing guidance by Hermano Queiroz and also supported by FAPESP. This showed that manganese continued to flow from the soil into the water for up to two years after the arrival of the tails and observed high levels of manganese in two species of fish. eaten by the local community (Cathoropus spixii and Genidens genidens).

“After these years of research, we are able to design phytoremediation programs with confidence and stability,” Ferreira said.

Armanda Duim Ferreira is doing two field tests. One of them is about trying ways to increase cattail biomass production and the amount of metal burned by the plant. The project combines the use of organic acids and iron reducing agents with agronomic practices such as the frequency of good harvesting, planting and fertilization with a view to reducing the time taken. perform phytoremediation.


The researchers gained insights into the Rio Tinto microbial community


More information:
Amanda Duim Ferreira et al, Iron disaster in a disturbed stream: Comparing the powers of plants and their effects on phytoremediation, Personal Journal (2022). DOI: 10.1016 / j.jhazmat.2022.128216

Directions: Water plants can do better at removing pollution from iron mine tails, study report (2022, March 31) retrieved March 31, 2022 from https://phys.org/news /2022-03-aquatic-effective-contamination-iron-tailings .html

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