Interactions Between Land Use and Local Lithology on Phosphorus Distribution in Northrup Creek Sediments, Monroe County, New York

Abstract

Phosphorus, a key nutrient in many aquatic systems that limits the growth of algae, plays a key role in the occurrence of eutrophication and toxic algal blooms. Past research has shown that land use and lithology are major contributors of phosphorus in a creek. High levels of organic phosphorus occur in agricultural areas of a watershed, and high levels of inorganic phosphorus occur in residential areas, especially near waste water treatment plants. The bedrock of an area also influences the chemical composition of stream sediment. Limestone bedrock results in high levels of calcium associated phosphorus. Northrup Creek, a mixed land use watershed in western Monroe County, New York, was examined to determine the main contributors of phosphorus in the creek. Fluvial sediment samples were collected from eleven sites in the Northrup Creek to determine if phosphorus levels in the creek were correlated to the type of land use occurring in specific sections of the watershed. Phosphorus fractionation was performed to analyze the phosphorus distributions at each site, focusing on organic phosphorus, iron-manganese, aluminum, and calcium associated inorganic phosphorus. Land use land cover data was used to determine the land area percentages and hectares of agricultural and residential land in each stream segment. The phosphorus concentrations and percentages from the total phosphorus level were correlated to land use data using a Kendall Tau correlation coefficient. Linear regressions were also run to test the statistical significance of the relationship between phosphorus concentration and land use. The results were not statistically significant and could not be used to support the hypothesis statement that agricultural areas of the catchment would have high levels of organic phosphorus and residential areas would have high levels of inorganic phosphorus.