Harmful effects of acid rain have been considered a serious problem. In this paper we have studied the ability of several common types of leaves to mitigate the effect of acid rain via the ability of these leaves to act as buffers in water.
The pH of leaf suspensions of cypress, pine, oak, cinchona and ficus leaves has been determined and its variation with time has been followed. The buffer capacities for these leaf suspensions have also been determined at several times over a long period of time. The effect of dilution on this buffer capacity has been studied. The speeds at which the various leaf suspensions adjust their pH value when disturbed have been studied.
The capability of the various leaves studied here to act as a buffer can be arranged in the order:
Decaying leaves have been found capable of resisting the effects of acid rain via their ability to buffer water.
In a previous study the buffering action of five common types of leaves (cypress, oak, pine, cinchona and ficus) was investigated. In the present study the effects of several factors on the buffering ability of these leaves have been studied. These factors are acidity, presence of foreign ions, concentration of leaves and location.
The studied factors have been found not to affect the pattern of variation of pH of the leaf suspensions with time but to affect the pH value reached by these suspensions.
Ficus leaves have shown a distinct copability of neutralizing acidic waters.
Batch and isotherm studies were carried out to compare the effectiveness of decaying leaves of cypress (Cupressus sempervirens), cinchona (Eucalyptus longifolia) and pine (Pinus halepensis) to adsorb lead from its aqueous solution and to study the leaf interaction effects. Lead removal increased with increasing concentrations of both lead ions and the plant leaves employed. Removal efficiency of leaves followed the decreasing order: pine>cypress>cinchona. While cinchona leaves showed an antagonistic effect on the removal efficiencies of cypress, pine, and a combination of cypress and pine leaves, the effect of cypress on the removal efficiency of pine leaves was additive. The adsorption of lead by cypress and cinchona leaves was well defined by both the Freundlich and Langmuir isotherms, but only the Freundlich isotherm was adopted for pine leaves. Desorption of lead from leaves upon standing in deionized water was minimal.