Project Number:
DNR-171
Other Project Number:
WR01R019
Funding Year:
2001
Contract Period:
Funding Source:
DNR
Investigator(s) and affiliations:
B. A. Browne, University of Wisconsin–Stevens Point;
W. M. DeVita, University of Wisconsin–Stevens Point;
D. J. Mechenich, University of Wisconsin–Stevens Point
Abstract:
Introduction: The leakage of NO3 and pesticide residues from agricultural landscapes to groundwater has important implications for drinking water quality and aquatic ecosystem health. This leakage increased greatly along with the large increase in fertilizer-N and pesticide use that began about 1960 (e.g., Hallberg et al., 1989). Though substantial progress has been made at describing current NO; and pesticide groundwater conditions (e.g., VandenBrook et al., 2002; Kolpin et al. 1993a; 1993b), what conditions the future will bring remain unclear. We expect that for a given area or a given aquifer, the average pollutant concentration and pollutant load (“load” can be thought of as the amount of pollutant stored in an aquifer) will increase until an equilibrium is reached with modern pollutant leakage. Equilibrium requires that either (1) denitrification and pesticide degradation mechanisms eliminate pollutants, or (2) modern groundwater with its associated pollutant load penetrates an entire aquifer thickness.
This study examines the penetration of nitrate and pesticide residues into a Wisconsin central sand plain aquifer (Figure 1) in the vicinity of the Town of Stockton (“Stockton Study Area”). The objectives are to:
- understand the input, fate, and origin of groundwater nitrate in the study area;
- describe the occurrence and concentration of pesticide residues, primarily those of chloroacetanilides and atrazine;
- determine the extent to which nitrate and pesticide residues have penetrated the study-area aquifer;
- and ascertain whether the residues are accumulating, or if a steady-state condition has been reached.