Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Aquatic Plant Sequesters Toxins, Removes Contaminants from Wetlands

25.08.2004


Researchers have found that a common aquatic plant removes many persistent organic compounds that are discharged into natural waters and engineered wetlands.

Environmental engineers at the Georgia Institute of Technology have found that various chlorinated, fluorinated and mixed chloro-fluoro compounds are taken up and sequestered in the plant tissue of their model plant species – duckweed (Lemna minor), a floating aquatic plant. These organic compounds are representative of the pool of persistent compounds discharged into the nation’s waters. Sources include agro-chemicals, such as pesticides, and pharmaceutical residuals, such as those from anti-depressants, which are excreted in human waste.

Though the compounds are sequestered in the plant, there is concern about their ultimate fate in the ecosystem as the plants are eaten by animals, or die and decay in wetland sediments, researchers noted.



“The compound goes into the plant, and the plant has no choice about the uptake. Whether the compound is water-loving or water-hating does not appear to be a major factor,” explained Professor Michael Saunders of the School of Civil and Environmental Engineering. “… And our plants take up this large class of compounds quickly, at rates faster than bacteria would degrade the contaminants.”

These findings have implications for both water monitoring regulations and wastewater treatment practices.

Saunders’ Ph.D. student Dawn Reinhold will present their research on Aug. 23 at the 228th national meeting of the American Chemical Society in Philadelphia. Reinhold conducted the research, in part, with former Ph.D. student Jacqueline Tront, who graduated in May 2004, and Angela Wrona, also a recent graduate. This study built upon previous research in Saunders’ lab funded by the U.S. Department of Energy.

The research has focused on halogenated phenolic molecules as indicators of chlorinated, fluorinated and mixed chloro-fluoro compounds in natural waters and engineered wetlands. Previously, researchers found that various chlorinated phenols were sequestered in duckweed cell tissue. The current study shows that mono, di and tri fluoro-phenols and mixed chloro-fluoro phenols are also taken up and sequestered at varying rates.

These compounds can be toxic to duckweed, so the plant has evolved a defense mechanism to deal with the threat, Reinhold explains. Duckweed does not degrade the compound, so the plant fixes it inside cell walls and tissue, eliminating the compounds’ toxic effect on the plant. She compared this process to human excretion of toxic products. “Plants don’t always have the option of excretion, so they package it away into their cell tissue,” she explained.

This research has led Saunders and his students to believe duckweed and probably other aquatic plants are acting as “sinks” for persistent organic compounds. Saunders noted that regulators monitoring contaminants in the water may be missing something by not considering the plant uptake of these compounds – a process that is affecting the overall removal time of the contaminants from the water.

“These types of compounds we have studied are emerging in the regulatory sector as the ones we need to know more about,” Saunders says. “They may soon meet with more regulatory control. They are not well regulated now.”

Of some concern is the movement of these contaminants up the food chain by ducks that feed on duckweed. Researchers are also interested in what happens to these contaminants when the plants die and decay in wetland sediments. They are likely being degraded by microbes in the sediments, Saunders said. Both processes may be areas of future research for Saunders and his students.

The researchers’ current findings may also have an impact on water treatment and reclamation practices. “Are we taking advantage of duckweed’s ability to remove contaminants from the water?” Saunders asked. “The answer is ‘yes, but indirectly.’ Constructed wetlands are used in some places as a means of removing nitrogen and phosphorus from treated wastewater. These wetlands are not designed for duckweed and other plants to remove organic contaminants, but it’s happening even though it’s not generally recognized or included with the design concept…. So here’s another tool in the toolbox for getting additional removal of contaminants.”

In the next phase of this research, Saunders’ research team will investigate whether duckweed sequesters additional compounds – those in the tri-fluoro methyl group. These compounds are found in medications such as Prozac and in pesticides.

Reinhold will also culture undifferentiated plant cells – similar to stem cells in humans – to determine how quickly duckweed processes and metabolizes the studied compounds. Researchers want to understand this activity because it may be an indicator of metabolic inhibition by the contaminants. Plants may take up a small amount of the contaminant and then stop, Reinhold said. “It looks like the overall uptake rate is highly dependent on plant metabolic rates based on the Ph.D. work of my colleague Jackie Tront,” she added.

The researchers’ overall goal is to create a modeling tool that measures the plant’s rate of oxygen production -- an indicator of the organism’s health -- in response to its uptake of various contaminants at various rates.

“We know that if oxygen activity is shut down with contaminant uptake, this process is having an impact on the environment,” Saunders said. “This shows the contaminant is having an impact at a lower concentration than if you are just monitoring how many plants die (such as is the case with a current EPA suite of ecotoxicology testing in waterways). Then we can go back to the regulators and give them some insight into how these trace levels of persistent organic compounds are affecting the ecological balance out there.”
“…. We may find that nature is taking care of this problem for us,” he added. “The question is whether we can put these compounds into a wetland system and put them back into the global carbon cycle and call it sustainable. The answer is that maybe we can, but we don’t know for sure yet.”

| newswise
Further information:
http://www.gatech.edu
http://www.gtresearchnews.gatech.edu

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling 'fast fashion' to reduce waste and pollution
03.04.2017 | American Chemical Society

nachricht Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>