Phytofiltration of copper from contaminated water: growth response, copper uptake and lignin content in Elsholtzia splendens and Elsholtzia argyi.

Phytofiltration of Cu from water by Elsholtzia plants were investigated hydroponically. Both E. splendens and E. argyi could effectively clean up lower Cu contaminated water, probably attributed to their extremely high surface area of roots. The removal rate of Cu was concentration-dependent and showed a monotonic decline with time. At higher external Cu concentration, the growth of E. argyi has been considerably inhibited while E. splendens still grew normally. E. splendens has the greater capacity to absorb Cu to roots from water and translocate Cu from roots to shoots. Lignin in roots probably has no significant effect on immobilizing Cu.