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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 verticillata, N. 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:
[email protected] |
