Sweating the Small Stuff Lauren Law and Ena Vu Vancouver Technical Secondary Floor Location : M 101 V

The purpose of our project was to experiment how the accumulation of particulate matter on the surface of leaves affect the ability of light to induce plants and trees to undergo transpiration.

Particulate matter (PM) is an air pollution which consists of dust, pollen, dirt, and polycyclic aromatic hydrocarbons (like soot and ash). Particulate matter poses a serious danger to human health, especially causing respiration problems like aggravated asthma, coughing, wheezing, shortness of breath and lung damage. There is a wide range of studies done on how particulate matter affects humans, but not much study has been done on how PM affects the environment.

One of us performed a project last year called, "It Takes your Breath Away", and the research done showed that the leaves of trees and plants act as filters, cleaning our air. We also have a friend that went running one day and skimmed the leaves of a bush as he ran. After running, his white shirt turned black where he had skimmed the leaves and it was suggesting that there must be a heavy accumulation of PM on the leaves. This event was what spurred us to want to study this topic.

We decided to test this experiment by observing how transpiration in laurel leaves is affected when they have different amounts of PM on their surface. We did this by performing a transpiration test using a potometer and a grow light. Transpiration is the loss of water in leaves through evaporation which is a process induced by light hitting the surface of the leaves and causing stomata on the leaves to open. We hypothesized that leaves with heavy accumulations of PM on the surface of them will undergo less transpiration than leaves with little accumulations of PM. We collected leaves from laurel bushes from various locations in Vancouver. These locations were organized into three categories based on the number of cars that passes by in one minute: cars between 0-20, car between 20-40, and cars between 40-60. Then the leaves collected would be placed into our potometer and it would be exposed to a grow light, which was acting as artificial solar light.

In our results, it seems to back up our hypothesis because we found that PM does have an affect on the transpiration of leaves. Our research suggests that PM can absorb or deflect/scatter solar light, so we believe that that the particulates on the surface of the leaves is acting as an extra barrier of allowing the light to hit the stomata to induce them to open.

Our data is meaningful because it educates the public about how PM is hurting our plants and trees. As a community, we rely so heavily on the ability of our trees and plants to produce oxygen, clean, and filter out our air. If this ability is be jeopardized by PM, then it forces us to find alternative ways to help protect our environment.