Featured Research

from universities, journals, and other organizations

Nanotubes in environment 'rob' green algae of space and light

Date:
November 8, 2011
Source:
Empa
Summary:
Nanoparticles such as carbon nanotubes, which are found in an ever-increasing number of products, are ending up more and more frequently in our surroundings. If and how they affect aquatic ecosystems are questions which are still unanswered. An new study shows that while carbon nanotubes do not have toxic effects on green algae they do inhibit its growth by depriving the plant of light and space.

Photosynthetic activity of the green algae made visible by fluorescence.
Credit: Image courtesy of Empa

Nanoparticles such as carbon nanotubes (CNT), which are found in an ever-increasing number of products, are ending up more and more frequently in our surroundings. If and how they affect aquatic ecosystems are questions which are still unanswered. An Empa study shows that while CNTs do not have toxic effects on green algae they do inhibit its growth by depriving the plant of light and space.

Related Articles


Carbon nanotubes (CNTs) are up to 100,000 times thinner than a human hair and as light as plastic. Despite this they have a higher tensile strength than steel, are harder than diamond and conduct electricity better than copper. These properties make CNTs a raw material with a very promising future. All over the world possible applications are being investigated, including use in solar cells, plastics, batteries, medical technology and the purification of drinking water.

With the increasing industrial production of CNTs now reaching the level of hundreds of tons per year, the quantity of these particles which could be released into the environment has also risen. Certain studies have raised the possibility that CNTs lodged in the lungs might cause similar health effects as do asbestos fibers. An interdisciplinary team of scientists from Empa and the Agroscope Reckenholz-Taenikon (ART) Research Station have now begun investigating the fundamentals of how CNTs behave when they are deposited in waterways and lakes.

Algae remain healthy but grow slower

In the course of the project, which is financed by the Swiss National Funds, researchers further developed a standard chemical method in order to measure the growth and photosynthetic activity of green algae exposed to CNTs. They discovered that even in the presence of high concentrations of CNTs the algae retain normal levels of photosynthesis, although growth rates are reduced. Also noticeable was that when CNTs are added to the algae suspension, its color darkens and the algae forms clumps with the nanotubes. Despite this there is no evidence that the nanotubes are absorbed by the plants.

The investigators came to the conclusion, therefore, that the algae grow more slowly because they stick together as a result of the presence of CNTs and therefore receive less light. To prove this, they developed two further tests which allowed them to measure quantitatively the shadowing and agglomeration effects the nanotubes had on the algae. The results show that the slower growth of the organisms is in actual fact primarily due to these two factors. The conclusion is therefore that CNTs are not directly toxic to green algae, as earlier studies indicated. In the presence of CNTs, algae simply do not enjoy ideal growth conditions because, like land plants, they need sufficient room and light to do so. The clumping and shadowing effects which were observed only manifest themselves at elevated CNT concentrations of more than one milligram per liter, however. These levels of carbon nanotubes concentrations are currently unlikely to be met in the environment.

"Our study shows how difficult is to understand in detail the effect of nanomaterials on organisms," says Empa and ART researcher Fabienne Schwab. The results will help to test other nanoparticles to ensure that the safety of humans and their environment is guaranteed. Empa researcher Bernd Nowack advises that until comprehensive, long term results are available for complex organisms such as green algae, nanoparticles (particularly unbound nanoparticles) should not be released into our environment.


Story Source:

The above story is based on materials provided by Empa. Note: Materials may be edited for content and length.


Journal Reference:

  1. Fabienne Schwab, Thomas D. Bucheli, Lungile P. Lukhele, Arnaud Magrez, Bernd Nowack, Laura Sigg, Katja Knauer. Are Carbon Nanotube Effects on Green Algae Caused by Shading and Agglomeration? Environmental Science & Technology, 2011; 45 (14): 6136 DOI: 10.1021/es200506b

Cite This Page:

Empa. "Nanotubes in environment 'rob' green algae of space and light." ScienceDaily. ScienceDaily, 8 November 2011. <www.sciencedaily.com/releases/2011/11/111104090711.htm>.
Empa. (2011, November 8). Nanotubes in environment 'rob' green algae of space and light. ScienceDaily. Retrieved March 27, 2015 from www.sciencedaily.com/releases/2011/11/111104090711.htm
Empa. "Nanotubes in environment 'rob' green algae of space and light." ScienceDaily. www.sciencedaily.com/releases/2011/11/111104090711.htm (accessed March 27, 2015).

Share This


More From ScienceDaily



More Matter & Energy News

Friday, March 27, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Amazon Complains U.S. Is Too Slow To Regulate Drones

Amazon Complains U.S. Is Too Slow To Regulate Drones

Newsy (Mar. 25, 2015) Days after getting approval to test certain commercial drones, Amazon says the Federal Aviation Administration is dragging its feet on the matter. Video provided by Newsy
Powered by NewsLook.com
Smartphone Use Changing Our Brain and Thumb Interaction, Say Researchers

Smartphone Use Changing Our Brain and Thumb Interaction, Say Researchers

Reuters - Innovations Video Online (Mar. 25, 2015) European researchers say our smartphone use offers scientists an ideal testing ground for human brain plasticity. Dr Ako Ghosh&apos;s team discovered that the brains and thumbs of smartphone users interact differently from those who use old-fashioned handsets. Jim Drury went to meet him. Video provided by Reuters
Powered by NewsLook.com
China Wants to Export Its Steel Problem

China Wants to Export Its Steel Problem

Reuters - Business Video Online (Mar. 25, 2015) China is facing a crisis with a glut of steel and growing public anger over the pollution created by production. In a move to solve the problem, some steel mills are looking to relocate overseas. Jane Lanhee Lee reports. Video provided by Reuters
Powered by NewsLook.com
Robot Stays on Its Feet Despite Punishment

Robot Stays on Its Feet Despite Punishment

Reuters - Innovations Video Online (Mar. 24, 2015) Robotic engineers have modelled a two-legged robot to be fast and agile like an ostrich. The design is more efficient and stable than bipedal robots built to move like humans, according to its creators who abuse the poor machine to test its skills. Ben Gruber has more. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins