Queen's University researchers Niraj Kumar and Virginia Walker
New research just published in the Journal of Hazardous Materials by a team from Queens University has shown – probably for the first time – that nano particles could prove to be a threat to the environment. Nano particles are now commonly used in a range of household goods but research into it’s ecotoxicology is only just beginning.
This latest research concentrated on nano particles impacts on soil micro-organisms and the first signs are not good. Results show that when soil becomes contaminated with the chemicals survival of nitrogen-fixing bacteria (diazotrophs) were substantially diminished. The nitrogen-fixing bacteria were more than a million times more susceptible to silver nano particles than other soil organisms.
Nano particle experiments part of International Polar Year Initiative.
The experiment was supervised by Virginia Walker, a professor in the Department of Biology. It was part of the university’s contribution to The International Polar Year Initiative. The results were a surprise to the team as they were not expecting to see a major impact from contamination.
“Millions of tonnes of nanoparticles are now manufactured every year, including silver nanoparticles which are popular as antibacterial agents,” explained Walker, “We started to wonder what the impact of all these nanoparticles might be on the environment, particularly on soil.”
“We hadn’t thought we would see much of an impact, but instead our results indicate that silver nanoparticles can be classified as highly toxic to microbial communities. This is particularly concerning when you consider the vulnerability of the arctic ecosystem.”
The experiment involved using soil samples taken from unpolluted arctic environments and then contaminating them with different nanoparticle chemicals. The soils were examined over a 6 month period. The most toxic ones were the silver based nanoparticles. This type of particle is widely used in the textile industry. So called nano-silver has effective anti-microbial properties and is used in odour-reducing clothing.
Previous concerns of ecotoxic effect of nano-silver.
Previous research has shown that nano-silver can be toxic to the bacteria found in wastewater plants. A study by Zhiqiang Hu, assistant professor of civil and environmental engineering in University of Missouri College of Engineering showed that the particles reduced the bacteria involved with the removal of ammonia in wastewater. “We found that silver nanoparticles are extremely toxic. The nanoparticles destroy the benign species of bacteria that are used for wastewater treatment. It basically halts the reproduction activity of the good bacteria.”
Potential concerns on environment of nano particles.
The new research by Walker though looked at impacts on an indigenous soil community rather than a specialist wastewater ‘man made’ community. The findings really does open up a whole range of questions over how ecosystems could respond to a growing presence of the chemicals in the environment.
It’s unlikely that agricultural ground will be greatly affected as any loss of nitrogen-fixing bacteria would be made up by spraying more fertilizer on the ground. A bit of a twist in the tail though is that one of the main pathways into the environment is through wastewater sludge that is sprayed on to fields as a conditioner and fertilizer. The very stuff that is being sprayed onto the fields could be killing off the natural nitrogen-fixing communities in the soil.
Concerns over the nitrogen fixing bacteria.
The wild environment is going to be the most at risk if nitrogen-fixing bacteria are badly affected by increasing deposits of nanoparticles. But the research is still at the very early stages. Does the nano-silver only affect the free-living nitrogen fixers? If those plants that have their own root nodules with symbiotic nitrogen-fixing bacteria (rhizobia) are not affected by the nanoparticles will we see a change in plant communities in some areas from grasslands to areas dominated by clovers and legumes? Will some shrubs such as alder be able to outcompete other shrubs and trees if ground nitrogen levels drop?
If nano-silver does prove to be detrimental to the environment then the impacts on the more extreme environments such as desert edges or polar and alpine areas could be substantial. These are regions where life clings right on the edge and any loss of nutrients could have devastating effects. While many nano chemicals appear to be relatively harmless perhaps those which are gaining a bit of a reputation for being toxic should be restricted in their widespread non-essential use until we understand their impacts better.
Incoming search terms:
- effect nanosilver on plant
- nanoparticle and pcb
- nanoparticles wordsearch
- nitrogen nanoparticles for plant use
