The Effect of Vegetated Roofs on Acid Precipitation Runoff

ii Vegetated, or “green ” roofs are used in urban architecture and sustainable building to capture stormwater and enhance urban wildlife. Most research to date has focused on their water retention capabilities, but green roofs also have the potential to treat anthropogenic acid precipitation in urban environments. More specifically, green roofs could reduce sulfate, nitrate and hydrogen ion concentrations in runoff. One previous study has demonstrated that nitrate was reduced in water draining from a green roof (Berndtsson, et al. 2006), but this unpublished thesis appears to be the first comprehensive study of the effects of vegetated roof materials on major ions and acidity in runoff. The objective of this current research was to test whether green roofs could significantly modify acidified precipitation. Experiments were conducted using a variety of materials commonly used in modern green roof design. Twenty different experimental roof surfaces, each with an area of 0.5 m2, were constructed and exposed to ambient rainfall during the 2008 growing season. Twent