A PRELIMINARY STUDY ON THE PRESENCE OF-HEAVY METALS IN AQUATIC PLANTS FROM A FRESHWATER WETLAND AT KELANIYA

K. G. S. Nirbadha, J. A. Liyanage, M. D. Amarasinghe

Abstract


Aquatic plants are known for uptake of heavy metals from water and sediments. Thisvery feature qualifies these plants as wastewater treatment agents. Capacity to absorb,heavy metals however, varies among plants. Three aquatic plants, Pistia stratiotes(floating), Limnocharis jlava (rooted) and Ipomoea aqualica (rooted plant with floatingrunners) from lriyawetiya wetland at Kelaniya were tested for the presence of copper,zinc, lead, nickel, cadmium, manganese, tin and chromium in the plant tissues.

P. stratiotes, L. jlava and 1. aquatica plants were collected from the inlets, outlets and themiddle part of the wetland and above heavy metal concentrations in acid-digested rootand shoot samples were measured separately using atomic absorption spectrophotometer.

Tin (Sn) is the heavy metal that was found in relatively large quantities in all threeplants, and Ipomoea aquatica recorded the highest content of Sn. Next highestoccurrence was observed with Cr and the contents were highest in the rooted plant, L.jlava, indicating that the sediment loads of Cr may be greater than the load in the watercolumn. All other heavy metals occur in relatively low concentrations in all three plantspecies, indicating partly the lower loading rates of these heavy metals in Iriyawetiyawetland.

Occurrence of heavy metals in the roots was generally higher than that of the shoots.Greater Cr concentrations were recorded from roots of floating species, P. stratiotes andI. aquatica than the rooted species, L. flava.

Except for cadmium (in P. slratioles) and manganese (in L. flava and 1. aquaticay;content of all the other heavy metals that occur in the plants that have been collectedfrom the inlets was greater than that of those collected from the outlet, indicating thewetlands' capacity to remove heavy metals from water and sediment through plantuptake.

 


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DOI: https://doi.org/10.31357/fesympo.v0i0.1534

DOI (PDF): https://doi.org/10.31357/fesympo.v0i0.1534.g705

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Proceedings of International Forestry and Environment Symposium, Sri Lanka. Published by Department of Forestry and Environmental Science, University of Sri Jayewardenepura