Hydrogeochemical Characterization of Prairie du Chien Bedrock Aquifer
Location
CSU 253
Start Date
26-4-2005 10:00 AM
End Date
26-4-2005 12:00 PM
Student's Major
Chemistry and Geology
Student's College
Science, Engineering and Technology
Mentor's Name
Bryce Hoppie
Mentor's Department
Chemistry and Geology
Mentor's College
Science, Engineering and Technology
Second Mentor's Name
Daniel Swart
Second Mentor's Department
Chemistry and Geology
Second Mentor's College
Science, Engineering and Technology
Third Mentor's Name
Trent Vorlicek
Third Mentor's Deparment
Chemistry and Geology
Third Mentor's College
Science, Engineering and Technology
Description
This research investigated the hydrogeochemistry of the Prairie du Chien confined bedrock aquifer in southeastern Minnesota. This bedrock aquifer has been found to be unusually enriched in organic matter, nitrogen (N)-family species, and phosphorous. Our analysis has supported the suspicion that this aquifer is atypical. Loss on ignition (LOI) measurements suggest high organic matter at levels 15-fold greater than average. GC-MS results show the presence of long, straight chain organics; however, surface contaminants (e.g., pesticides and pharmaceuticals) are below detection. AAS results indicate normal levels of As and elevated levels of Cu. In addition, total phosphorus (?) falls in the range 500-800 ppb which is an order of magnitude greater than typical values. Dissolved oxygen levels are very low, (i.e. 0.1 ppm), indicating hypoxia, which is also suggested by the presence of reduced N-species (e.g., 2 ppm NH3). Measures of water quality such as alkalinity, hardness, pH, and conductivity are normal. The observed abnormalities point to the same source: high levels of organic matter. Hypoxia as well as elevated P and N are likely due to the concentrated organic matter. The elevated organic matter content also facilitates the transport of copper and may indicate the presence of other metal species. Research will continue in the future, and focus on investigation of surface sources of organic matter, heavy metals, deep lateral transport, and any buried organic sources (e.g. peat layers).
Hydrogeochemical Characterization of Prairie du Chien Bedrock Aquifer
CSU 253
This research investigated the hydrogeochemistry of the Prairie du Chien confined bedrock aquifer in southeastern Minnesota. This bedrock aquifer has been found to be unusually enriched in organic matter, nitrogen (N)-family species, and phosphorous. Our analysis has supported the suspicion that this aquifer is atypical. Loss on ignition (LOI) measurements suggest high organic matter at levels 15-fold greater than average. GC-MS results show the presence of long, straight chain organics; however, surface contaminants (e.g., pesticides and pharmaceuticals) are below detection. AAS results indicate normal levels of As and elevated levels of Cu. In addition, total phosphorus (?) falls in the range 500-800 ppb which is an order of magnitude greater than typical values. Dissolved oxygen levels are very low, (i.e. 0.1 ppm), indicating hypoxia, which is also suggested by the presence of reduced N-species (e.g., 2 ppm NH3). Measures of water quality such as alkalinity, hardness, pH, and conductivity are normal. The observed abnormalities point to the same source: high levels of organic matter. Hypoxia as well as elevated P and N are likely due to the concentrated organic matter. The elevated organic matter content also facilitates the transport of copper and may indicate the presence of other metal species. Research will continue in the future, and focus on investigation of surface sources of organic matter, heavy metals, deep lateral transport, and any buried organic sources (e.g. peat layers).
