AGRICHEMICAL DETECTION IN A SHALLOW UNCONFINED AQUIFER AS INFLUENCED BY SAMPLING TECHNIQUE

The sample collection system may influence the ability to describe the complex temporal and spatial variation of contaminants Within an aquifer. The objective of this study was to evaluate the probability of detecting atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) using a bailer or skimmer in an unconfined aquifer located below an atrazine-treated surface soil. In the simulated aquifer, the surface skimmer collected more Br- than the fixed sampling port located 15 cm below the aquifer surface and bailer. In the unconfined aquifer, the probability of an atrazine detection was higher when samples were collected with a surface skimmer than a bailer. These results suggest that the ability to determine vertical transport of contaminants from surface soil to shallow aquifers at the point of agrichemical application is dependent on surface sampling of the aquifer.