Gomphrena claussenii is suggested here:

http://phys.org/news/2013-06-south-american-purifying-soils-contaminated.html

Maybe also of interest:

http://www.eurekalert.org/pub_releases/2012-09/cp-ssl091012.php

http://phys.org/news/2012-09-identification-rice-manganese-cadmium-uptake.html

Regards,

Joachim

A very good reference is the book "Trace elements from soil to human" (Springer, 2007) by Kabata-Pendias and Mukherjee. If this is unavailable, you may contact, for example, the first author; her coordinates and a presentation of the book are here: http://meetings.copernicus.org/www.cosis.net/abstracts/EGU2007/11054/EGU2007-J-11054.pdf.