Water hyacinth and Duck weed as indicator of heavy metal pollution in river Asa
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Date
2013-01
Journal Title
Journal ISSN
Volume Title
Publisher
EM publishers, India
Abstract
An investigation into the potentials of duckweed and water hyacinth as possible biomonitors of aquatic
environment was carried out in River Asa. Water, duckweeds and water hyacinths were collected from
six different locations along River Asa. The water and plant samples were analysed for physicochemical and heavy metal contents with standard methods. Result showed that temperature ranged from 25.35 to 31.20 °C. pH was high at site 1 and low at 5. Site 2 was more turbid (21.35 N.T.U.) and
TSS range was 182.0 – 218.4 mg/L. BOD and COD ranges were 7.78 - 13.90 mg/L and 129.00 - 150.30
mg/L respectively. Dissolved O2, alkalinity and total hardness ranged between 12.00 and 20.32 mg/L, 5.41
and 16.90 mg/L, 12.90 and 14.40 mg/L respectively. Phosphate and nitrate levels ranged between 0.44
and 3.43 mg/L, 0.64 and 1.41 mg/L respectively. Of all the heavy metals in the plant tissues, Cd and Cr
levels were highest. Except for Pb, no significant difference exists in heavy metal levels within the tissue of
the two aquatic plants. The positive correlation of Cd, Cr, Ni and Pb levels in duckweed as well as
those of Cd and Pb in water hyacinth to the levels in the river reflect the ability of the plants to monitor
these metals. The study concluded that duckweed and water hyacinth could therefore serve as useful tools
to monitor heavy metal pollution in rivers and other wetlands.