Clean and green - a moss that removes lead from water

Researchers at the RIKEN Center for Sustainable Resource Science (CSRS) in Japan have demonstrated that that moss can be a green alternative for decontaminating polluted water and soil. Published in PLOS ONE, the study shows that in particular, the moss Funaria hygrometrica tolerates and absorbs an impressive amount of lead (Pb) from water. 

Lead-contaminated water is a serious environmental concern that has recently proved to be disastrous when left untreated. Compounding the problem, the typical way to remove lead or other heavy metals from water requires fossil fuels and a tremendous amount of energy. As an alternative to these typical processes, phytoremediation is a method that uses photosynthesizing organisms to clean up soil or water contamination.

The CSRS researchers began their search for a phytoremediation-based removal method by looking at F. hygrometrica, a moss that is known to grow well in sites contaminated with metals like copper, zinc, and lead.

"We found that the moss can function as an excellent lead absorbent when in the protonema stage of development," says first author Misao Itouga. "This valuable ability means that moss protonema will likely make exceptional wastewater cleaners in mining and chemical industries."

To characterize the metal-absorbing ability of the moss, the team first prepared solutions with varying concentrations of 15 different metals and exposed them to F. hygrometrica protonema. After 22 hours of exposure, mass-spectrometer analysis showed that the moss cells had absorbed lead up to 74% of their dry weight, which is quite high and much higher than any of the other metals.