Twin Cities Seminar
Historical Trends and Spatial Distribution of Antibiotics in Minnesota Lakes and Rivers
Antibiotic therapy has been one of the greatest advancements in human and animal medicine. The rise in popularity and widespread use of antibiotics resulted in detection in the environment which is concerning because antibiotics are designed to be persistent and effective at small doses. The objective of this work was to quantify levels of human and animal use antibiotics spanning several major antibiotic classes (sulfonamides, macrolides, tetracyclines, and fluoroquinolones) in Minnesota lake sediments cores and river surface sediments. Sedimentary record of antibiotics was used to determine temporal trends, the major anthropogenic source, and the importance of natural production. Antibiotic concentrations in river surface sediments were used to determine spatial trends and transport of antibiotics in river systems. Antibiotics were extracted from sediment using accelerated solvent extraction and cleaned up by solid phase extraction prior to high pressure liquid chromatography coupled with electrospray ionization (positive) tandem mass spectrometry analysis. A historical record of usage trends for 12 human and/or animal use antibiotics (4 sulfonamides, 2 tetracyclines, 3 fluoroquinolones, 1 macrolide, trimethoprim, and lincomycin) was captured in a sedimentary record. Natural production of lincomycin may have occurred in one lake. Wastewater effluent appears to be the primary source of antibiotics in the studied lakes, with lesser input from agricultural activities. Varying spatial distribution of antibiotics were observed in the Minnesota rivers likely due to their specific anthropogenic uses, i.e. run-off of agriculture fields versus wastewater effluent.