NUTRIENT VARIATIONS OF SIX SURFACE WATER BODIES IN MCHENRY COUNTY, IL

This research analyzes water quality from several rural and suburban ponds in McHenry County, Illinois, with a goal of developing a better understanding of pollution sources and temporal variations in concentrations of nitrate, potassium, phosphorus, chlorine, and sodium. Over the past 25 years, the population of McHenry County has grown rapidly, with residential developments expanding into former farmlands. Yet, the county remains heavily agricultural, with roughly 60% of the surface area used for agricultural purposes. With growing concern over pollution of surface water bodies, this research analyzes concentrations of NO₃^-, P⁺, K⁺, Cl^-, and Na⁺ in the surface water sampled from six sites: two in subdivisions, two in farmland, and two in close proximity to major highways. Data were collected once a week from the beginning of June through the end of July, and twice during the first week of November 2016. Data were collected using two methods: the first method involved a color change test with Hach test kits to test for NO₃^- and Cl^- using 5 mL samples that were collected from the edge and surface of each water body. The second method tested for dissolved Na⁺, K⁺, and P⁺. Water samples were collected from the edge and surface of each water body and then pipetted onto filter papers. Filter papers were subsequently dried and analyzed using XRF spectroscopy. The highest concentrations of NO₃^- and Cl^- were 13.2 ppm and 0.4 ppm, respectively, with EPA limits of 10 ppm and 250 ppm, respectively. These highest levels probably correspond to the application of fertilizers in the spring and road salt applied during the winter that are washed into the water bodies. The highest concentrations of Na⁺, P⁺, and K⁺ were 215 ppm, 181 ppm, and 345 ppm of K⁺, respectively, compared with EPA limits of 20 ppm for Na⁺, 0.05 ppm for P⁺, and no limit for K⁺. These highest levels probably result from applications of fertilizers and roads salts as well as wastewater from nearby homes with water softeners. With NO₃^-, Na⁺, and P⁺ being over the EPA limit for most of the testing period there is cause for concern for downstream pollution as well as pollution of aquifers that recharge locally. Natural occurring P⁺ ranges from 0.005 ppm to 0.05 ppm, so the high levels of P⁺are of particular concern for ecosystems downstream, as eutrophication processes will increase.