The effect of heavy metals accumulation on the chlorophyll concentration of Typha latifolia plants, growing in a substrate containing sewage sludge compost and watered with metaliferus water

Typha latifolia plants, commonly known as cattails, were grown in a mixture of sewage sludge compost, commercial compost and perlite. Four groups (A, B, C and D) were irrigated (once every 2 weeks) with a solution containing different concentrations of Cd, Cu, Ni, Pb and Zn, where in the fifth (group M) tap water was used. At the end of the 10 weeks experimental period the mean concentration of Ni, Cu and Zn in the roots and leaves of the plants in the four groups was significantly larger to that of the plants of group M. A linear regression test satisfactorily correlated the metals' concentrations in the irrigation solutions with the metals concentration in the leaves and roots of groups A, B, C and D. The concentration of total chlorophyll, chlorophyll a (chla) and chlorophyll b (chlb) in the leaves of the developing plants was also monitored in 2 weeks intervals. Groups A, B, C and M presented an increasing concentration of total chlorophyll, with time. In group D (stronger solution), the mean total chlorophyll concentration was reduced from 1080.69 mug/g fresh weight (f.w.) in the 8th week to 715.14 mug/g f.w., in the 10th week, a probable evidence of inhibition. When statistically tested, it was suggested that there was no significant difference between the mean chlorophyll values of the groups in each set of samples, concluding that no significant toxic action was imposed in the plants by the metals. However, when similar statistical analysis was implemented in the ratios of chla and chlb, there was significant reduction of the ratios in groups D plants, suggesting some increase in chlorophyll hydrolysis due to the metals accumulation (toxic effect) in comparison with the other groups. (C) 2003 Elsevier Science B.V. All rights reserved.