With rising populations, human activity is directly increasing the amounts of nitrogen deposition. Maricopa County, Arizona, which encompasses the Phoenix metropolitan area, has seen an increase in population of 7.1% from 2010-2014 alone. This study explored the impact of nitrogen pollution on the environment resulting from human activity. The purpose of this research is to show how nitrogen deposition affects microbial communities in desert soils around the Phoenix metropolitan area. We measured microbial growth in carbon-utilization plates from soil samples taken from the inner-city (higher nitrogen deposition) and outer-city (lower nitrogen deposition) from either control plots or plots receiving nitrogen fertilization. The soil chemical and physical environment, such as the texture, moisture factor, and conductivity, and phosphate, nitrite, nitrate, and ammonium levels were used and analyzed through Principle Component Analysis in an attempt to explain the microbial carbon utilization data.
Results/Conclusions
Results showed that there were no significant differences in these microbial communities despite the different levels of soil nitrogen. There was very little difference in the average well color development and diversity of the microbial communities between the inner-city and outer-city soil samples, despite having greater levels of nitrogen deposition in the composition of inner-city soil samples. Though there was a slight increase in diversity between the west site and the other two regions, there was no proven impact on diversity between the three sites tested. This shows that the nitrogen deposition increase may not be as significant to the growth and diversity of microbial communities in soil as some other factors, such as precipitation, may have on these microbes.