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Highlights in Chemical Science

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Ionic liquids put zebra mussels off their food


27 February 2009

Non-lethal doses of ionic liquids can have a significant effect on aquatic ecosystems, claim US scientists. 

Ionic liquids are green alternatives to the volatile organic solvents that are released into the environment as a result of agriculture and manufacturing. But their solubility in water means that they can contaminate aquatic environments. Knowledge of their toxicity in these environments is limited, but even less is known about their non-lethal effects on aquatic organisms.
 
Now, David Costello and colleagues from the University of Notre Dame have studied how ionic liquids affect aquatic organisms' feeding rates as well as their survival.

 

zebra mussel

Ionic liquids decreased the zebra mussel's feeding rate

© Randy Westbrooks / US Geological Survey / bugwood.org
 

 

The team looked at zebra mussels, which feed by filtration and can tolerate high doses of ionic liquids. They fed the mussels algae and exposed them to six different ionic liquids. They found that while changing the heterocyclic base of the ionic liquid's cation had no effect, increasing the length of its alkyl chain increased toxicity and decreased the mussels' feeding rate. 'A reduction in algal consumption could allow increases in algal populations that are resistant to ionic liquids,' says Costello. 

'The work is a valuable contribution to the knowledge base that the scientific community is generating on potential harmful effects that will have to be considered if ionic liquids are to be used on a large scale,' says Johannes Ranke, an expert in the environmental risk assessment of ionic liquids, from the University of Bremen, Germany.

Costello says he hopes that within 5 to ten years, he will find more environmentally friendly solvents and that green solvents will be used more in general. He is currently investigating the nutrient cycle (the transfer of nutrients from one part of an ecosystem to another) in invasive species and contaminants and studying how contaminants affect nitrogen and phosphorus movement in the environment.

Ben Merison

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Link to journal article

Acute toxic effects of ionic liquids on zebra mussel (Dreissena polymorpha) survival and feeding
David M. Costello, Loretta M. Brown and Gary A. Lamberti, Green Chem., 2009, 11, 548
DOI: 10.1039/b822347e

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