To determine the combined effects of pesticide sorption and degradation under dynamic flow conditions, we designed an unsaturated soil column with several unique features. The column contains two series of ports on opposite sides along the length of the column. The design allows a controlled potential by keeping the column under uniform pressure, achieved by applying air pressure through the ports along one side of the column. Furthermore, by applying a downward unit hydraulic gradient, the water content within the column is spatially uniform. The design allows uniform aerobic conditions to be maintained in the column. It allows periodic sampling of both the gas phase and the solution phase, allowing calculation of mass balances. In addition, because the column itself is pressurized, the design does not require pressurized or depressurized chambers to maintain unsaturated flow, and collection or addition of solution can be done at atmospheric pressure. The presentation will show preliminary test results, discuss the usefulness and limitations of the column test, proposed further testing of the design and suggest how this test can be used to bridge laboratory batch studies and field experiments.

Unsaturated column for evaluation of pesticide behavior in soil

248th National Meeting (2014)

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