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Caroline Tillandsia usneoides: An Indicator to Air Pollution
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Continued...
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 and moss after being exposed to Helium for 10 days (bottom). After exposure trichomes are gone and moss is clearly dead.) Digital microscope images of live moss (top) and moss after being exposed to Helium for 10 days (bottom). (Click to view) For the second control, dry ice was used to obtain carbon dioxide. Again, I looked at the moss under the digital microscope and weighed it using the same analytical balance. I put approximately 15g of dry ice in each flask. After half of each cube had sublimated, I put the stopper in each flask. Pressure built up beneath each stopper as the dry ice continued to sublime and the stoppers popped off. This showed that the CO2 had filled the flask and the air was being pushed out, since CO2 is heavier than air. I kept the moss in the carbon dioxide for 10 days. Then, its weight change was recorded and the moss was inspected under the digital microscope. This time, the moss was a healthy light green color. [Moss before and after carbon dioxide exposure. (Click to view)]
From these results, I found that the Spanish moss could live and even grow, as seen from the negative weight loss, in the ESC for a period of 10 days. |
Each time the samples of Spanish moss were collected, I collected the moss off of the same branch of the same live oak tree in order to make sure that the moss was as similar as possible. Looking at the pollution results from January 2004 to October 2004, I was able to get an average amount of pollutants in the Houston air for carbon monoxide, nitrogen dioxide, and sulfur dioxide. I obtained these results from the monitor nearest to where the samples of Spanish moss were collected: (Air Quality Index and Lang C408).
For the acid rain, I collected rainwater in a sterile container and measured the pH. I found the average pH of Houston's water to be 4.5. In order to obtain carbon monoxide, nitrogen dioxide, sulfur dioxide, and acid rain, I synthesized them in my school's laboratory with teacher supervision. Carbon monoxide was made by combining eight drops of concentrated sulfuric acid with eight drops of formic acid (H2SO4 + HCOOH → CO + H2SO4:H2O; the sulfuric acid dehydrates the formic acid). I used the thermal method—the two chemicals were heated in a test tube and the waste was collected in one syringe and the carbon monoxide in the other syringe. A clamp was used to prevent mixing of carbon monoxide and the waste product (dilute sulfuric acid). Sulfur dioxide was made with sodium bisulfate and concentrated hydrochloric acid (H2SO4 + NaHSO4 → SO2 + NaCl + H2O). The reaction did not require heating but was collected in a similar manner to the carbon monoxide. Nitrogen dioxide was made by reacting copper with nitric acid (4HNO3 + Cu → 2NO2 + 2H2O + Cu(NO3)2). The reaction did not require heat as a catalyst, and the two chemicals were mixed in an Erlenmeyer flask and allowed to react. After the air was pushed out and the nitrogen dioxide produced, a syringe was placed over the opening and the nitrogen dioxide was collected. A wet piece of litmus paper was held over the opening of the flask; if it turned red I knew that I had collected pure nitrogen dioxide. Unlike the other two pollutants above, the nitrogen dioxide had to be made each day since it was so corrosive and could not be kept in the plastic syringe for long. The acid rain was made by mixing three liters of water with 250ml of sulfuric acid and 125ml of nitric acid. Small amounts of sodium hydroxide, a base, were added to the solution until pH 4.5 was reached. While synthesizing these "pollutants" in the hood, I wore goggles, an apron, and gloves and kept MSDS sheets on hand for all chemicals. |
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