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 aqui fer. The objective of this study was to evaluate the probability of de tecting atrazine loro-4-ethylamino-6-isopropylamino-1,3,5-triazine) us ing a bailer or skimmer in an unconfined aquifer located below an atra zine-treated surface soil. In the simulated aquifer, the surface skimm er collected more Br- than the fixed sampling port located 15 cm below the aquifer surface and bailer. In the unconfined aquifer, the probab ility of an atrazine detection was higher when samples were collected with a surface skimmer than a bailer. These results suggest that the a bility to determine vertical transport of contaminants from surface so il to shallow aquifers at the point of agrichemical application is dep endent on surface sampling of the aquifer.