Effect of Basement Sump Pump Effluent on the Growth and Physiology of Urban Black Ash and Green Ash Ornamental Trees

Abstract

The effect of basement sump pump effluent discharge in proximity to boulevards and ornamental trees was studied at several sites near Edmonton, Alberta, Canada throughout the summer of 1996. The growth, leaf petiole water potentials, and gas exchange of black ash (Fraxinus nigra) and green ash (F. pennsylvanica) trees were measured at sites with and without nearby sump pump effluent discharge. Black ash trees had higher mortality, altered water relations, and significantly lower caliper increase at the site with sump pump effluent discharge compared to trees at the site without effluent discharge. Green ash trees situated away from sump pump effluent discharge had significantly greater caliper increase than trees situated near effluent discharge. Furthermore, salt injury symptoms were observed on both species of trees located at sites with nearby effluent discharge. Our results demonstrate the importance of monitoring sump pump effluent discharge and its effects on boulevard ornamental trees in areas where soils are poorly drained or contain high levels of salts. It is recommended that basement sump pump effluent discharge hoses should be positioned away from boulevards and ornamental trees.