HYDROLOGIC DIFFERENCES BETWEEN PRAIRIES AND WETLANDS: A CASE STUDY FROM NORTHEAST IOWA

Once a week, for eight weeks (May 15 through July 13, 2010), water was collected and analyzed from 8 sites in two different, yet active hydrologic systems. Data was collected directly out in the field and back in the lab. Thirteen different parameters were tested to study the quality of the water and to help determine differences and similarities between a wetland and a prairie system in northeast Iowa. The biota of each system seemed to influence the values of E. Coli. Besides, animal’s fecal matter can significantly increase the E. Coli concentration in the water. The prairie averaged 20 colonies per 100ml, where the wetland’s average exceeded 200. The wetland was home to numerous species of animals, unlike the prairie which only had a few. Dissolved oxygen (D.O.) was also found to have a major impact on the differences of the two systems. The wetland’s biochemical oxygen demand (BOD) values mostly exceeded 8 mg/L compared to 3 mg/L in the prairie. Bacteria consume D.O. when breaking down organic material. The prairie’s BOD levels were quite lower which could limit the amount of the bacteria in the water. The lack of bacteria is causing the prairie water to become over burdened with dead plant matter. This is causing the turbidity values in the prairie to range from 25 to 300 NTU. When compared to the wetland’s average of 22 NTU, the effect that D.O. plays is evident. A relatively higher level of BOD can be expected in wetlands due to the photosynthetic release of free oxygen by numerous aquatic plants that generally thrive in this kind of hydrologic system. The pH of the two systems was also found to be very different. The wetland’s pH was on average 8.5 which is more basic than the prairie’s average of 6. It is believed that location has an influence in these values. The prairie sits higher in elevation and could possibly be affected by meteoric water which is slightly acidic due to dissolved carbon dioxide and low mineral content. The wetland, which is lower in elevation and possesses deeper water bodies, is likely to have more interactions with ground water. Due to the limestone bedrock, the ground water will be slightly basic, thereby increasing the pH levels of the wetland system. This study shows that water chemistry can be a powerful tool to define variable hydrologic systems in areas that are not significantly impacted by urban or industrial activities.