Water quality changes in a post-herbicide treated water hyacinth (<i>Eichhornia crassipes</i> (mart.) Solm-laub.) infested aquatic environment

Abstract

Water quality changes after in situ chemical control of water hyacinth (Eichhornia crassipes (Mart.) Solm-Laub. using five chemical products were monitored in a green house experiment. The observed changes in water quality coincided with the loss of treated plant photosynthetic activities, submerging of the dead plants in water and the subsequent decomposition and dissolution processes. Treatment in all cases significantly (P < 0.05) increased the mean alkalinity, pH, conductivity, organic matter, ionic and the solids contents of the water 28 days after treatment. Irrespective of herbicidal treatment, mortality of water hyacinth and subsequent decay in situ significantly lowered (P < 0.05) the amount of dissolved oxygen in the various treated media below 1.0 mg/L.


Key words: Water hyacinth, water quality, herbicide.


Journal of Aquatic Sciences Vol.17(2) 2002:140-144