ASSESSMENT OF SO2 POLLUTION IN CENTRAL PARK BY DNA BARCODING OF LICHEN SPECIMENS

The purpose of this study was to assess the level of sulfur dioxide pollution in Central Park using lichens as index organisms. It was hypothesized that there would be differences in the types of lichens in Central Park due to varying exposure to sulfur dioxide air pollution. By determining the trophic level of each species, we would be able to determine the tolerance each species of lichen has to sulfur dioxide. Thirty samples of lichens were collected and located throughout Central Park. By using PCR and gel electrophoresis, the nucleotide sequence of twenty of the thirty samples were successfully determined. Out of the remaining samples, eleven passed the quality control test for further DNA sequencing analysis. The trophic levels of these eleven successful species determined that the sulfur dioxide levels vary throughout the park. The DNA Subway website was used to compare the sample sequences. BLAST, a program featured on the DNA Subway website, was used to determine the species of our samples by using gene databases (GenBank, BOLD Systems, and Encyclopedia of Life). It was observed that lichens with a high tolerance for sulfur dioxide generally populated most of the southern part of Central Park, and lichens that are very sensitive to sulfur dioxide lived in the northern half. It was also observed that the southern half of Central Park had more tourist attractions and was considerably busier than the northern half, which is consistent with the types of lichens found in these areas. There were a few exceptions with sensitive lichens living in a heavily polluted area. However these species were not thriving and were very small in quantity. In conclusion, this experiment showed the detrimental effect of air pollution on the population of lichens in heavily polluted areas.