Accumulation of cadmium, chromium, and zinc by the moss Sphagnum papillosum Lindle

In a series of laboratory experiments employing radiotracer methodology, the uptake of Cd, Cr, and Zn by Sphagnum papillosum Lindle moss from solutions of deionized water and bog water was investigated. Bioaccumulation of the metals was a passive process, since living and dead moss accumulated metal equally. No significant differences were found in metal uptake rates from single metal solutions and mixed metal solutions, suggesting insignificant competition between the metals occurred at the low concentration range used (10^-10 to 10^-7 M). Metal uptake conformed with Freundlich adsorption isotherms. Concentration factors of metals in Sphagnum papillosum in bog water (10³ for Cd and Zn, 10² for Cr) were lower than in deionized water (10⁴ for Cd and Zn, 10³ for Cr), possibly due to metal complexation by dissolved organic matter, competition by other major cations present in the bog water (Na⁺, K⁺, Mg²⁺, Ca²⁺) or complexation by chlorides in the bog water. While earlier studies have demonstrated the potential of using sphagnum mosses for monitoring environmental metal contamination, these experiments are the first to assess metal uptake in moss using low, environmentally realistic metal concentrations. The results confirm that mosses would be very effective bioindicators of environmental metal concentrations because the concentration of metal in the moss rapidly and directly reflects the metal concentrations in the ambient water.