Removal of heavy metals from polluted waters by Hydrodictyon reticulatum (Linn.) lagerheim

Abstract

A preliminary survey of a pond in Unnao District, India, for heavy metal pollution indicated that the water was contaminated with manganese and iron at levels many times higher than permissible limits. The pond supported the growth of various aquatic plants and luxuriant growth of Hydrodictyon reticulatum, which dominated the plant community. Under natural conditions, the alga showed an unusually high content of heavy metals, including copper, cadmium, chromium and lead. The alga accumulated very high amounts of other heavy metals, especially iron and manganese, although the concentration in the water was quite low. Under simulated conditions, maximum uptake and bioaccumulation of heavy metal ions occurred within 48 h. At phytotoxic concentrations, chromium and cadmium inhibited biomass production, and reduced the chlorophyll, carotenoids and protein contents of the alga. The metal uptake was pH-dependent, and at a maximum under acidic conditions. The dominance of H. reticulatum in such an environment may help remove relatively large loads of heavy metals from the polluted waters.