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Vol. 15 No. 4 - October 2009

Biosorption of Copper in Aquatic Macrophytes

By: Abida Begum*

Aquatic macrophytes are unchangeable biological  filters  and  they  carry  out purification  of  the  water  bodies  by accumulating  dissolved  metals  and toxins  in  their  tissue. A phytoremediation  study was carried  out  to ascertain  the  degree  of  copper absorption  in  the  following  aquatic macrophytes.  The aquatic plants (biomonitors) Hydrilla  verticillata, N. nucifera, Eichhornia crassipes, Ipomoea aquatica Forsk, Typha angustata Bory & Chaub, Echinochloa colonum (L.) Link. and Vallisneria spiralis L. were collected from Bellandur Lake  located  in east of Bangalore. Based on  the  absorption capacity observed  in macrophytes was E. crassipes>H. verticillata>N. nuci fera>  Vallisneria  spiralis> Echinochloa  colonum>  Typha angustata>  Ipomoea aquatica.

Macrophytes are aquatic plants, growing in or near water that are either emergent, submerged or floating. Macrophytes are beneficial to lake because they provide food and shelter for fish and aquatic invertebrates. They also  produce  oxygen,  which  helps  in overall  lake  functioning,  and  provide food  for  some  fish  and  other wildlife. Heavy metal pollution is one of the main problems for the  ecosystem  due  to technological  development.  Diverse industrial wastes have aggravated the problem of water pollution.  This problem becomes complex because of the  qualitative  and  quantitative differences  in pollution according  to  the industries involved, and due to the non-degradability  of  inorganic  pollutants like heavy metals which are hazardous when  discharged  into  a  water  body. Several studies have shown that constructed wetlands are very effective in removing heavy metals from polluted wastewaters. Algae  and  aquatic plants play  a  key  role  in  aquatic  ecosystems because  they  are  at  the  base  of  food webs. Also, they are a food resource and provide oxygen and  shelter  for  many aquatic organisms. They also contribute to the stabilisation of sediments and bio concentration of compounds and are used as bioremediatives.  Direct discharge of contaminants increase the concentration  of  trace  elements  in aquatic  systems,  thus  resulting  in  their accumulation  in  sediments.  In  aquatic systems,  where  pollutant  inputs  are discontinuous  and  pollutants  are quickly  diluted,  analyses  of  plants provide  time-integrated  information about  the  quality  of  the  system. Phytoremediation  has   several  advantages  and  is  the most  significant one  in  study  of  sub-lethal  levels  of bioaccumulated  contaminants  within the  tissues/components  of  organisms, which  indicate  the  net  amount  of pollutants  integrated  over  a  period  of time. Biomonitoring of pollutants using some  plants  as  accumulator  species, accumulate relatively large amounts of certain  pollutants,  even  from  much diluted  solutions  without  obvious noxious effects. 

The  aquatic  plants  (biomonitors) Hydrilla  verticillataN.  nucifera, Eichhornia crassipes, Ipomoea aquatica Forsk, Typha angustata Bory & Chaub, Echinochloa  colonum  (L.)  Link,.  and Vallisneria  spiralis  from  the  lake were selected  during  February  2009  as passive biomonitors  for  estimating  the toxicity  status  induced  by  the  heavy metal  Copper.  Aquatic plants were thoroughly washed to remove all adhered soil particles. Samples were cut into small pieces, air dried for 48 hours and  finally dried at 85 C  in hot air oven for  two hours.  In warm condition, the samples were ground and passed through 1 mm sieve. Macrophytes fine powder samples (2.5 g/50 mL distilled water) were subjected to acid digestion by adding 8 mL concentrated nitric acid on hot plate and filtrate was diluted up to 50 mL with distilled water. Heavy metals analyses were performed on an Atomic Absorption Spectrophotometer.

This study reveals that the observed level of copper in E. crassipes (124-340 ppm),  H.  verticillata  (120-300),  N. nucifera  (109-287  ppm),  Vallisneria spiralis  (102-276  ppm,  Echinochloa colonum  (98-254  ppm) ,   Typha angustata  (75-205  ppm),  Ipomoea aquatica  (52-145 pppm). The order of accumulation of copper observed was E. crassipes>H.  verticillata>  N.  nucifera>  Vallisneria  spiralis> Echinochloa  colonum>  Typha angustata>  Ipomoea aquatica.

Phytoremediation  has   several  advantages  and  is  the most  significant one  in  study  of  sub-lethal  levels  of bioaccumulated  contaminants  within the tissues/components  of  plants/ organisms,  which  indicate  the  net amount of pollutants  integrated over a period  of  time.  Biomonitoring of pollutants  using  some  plants  as accumulator  species,  accumulate relatively  large amounts  of  certain pollutants,  even  from  much  diluted solutions  without  obvious  noxious effects.

Assistant Professor, P.E.S School of Engineering, (1 KM before electronic city), Bangalore-560100, India E-mail: drabid.drabida@gmail.com


This article has been reproduced from the archives of EnviroNews - Newsletter of ISEB India.


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