An Improved Technique for Soil Solution Sampling in the Vadose Zone Utilizing Real-Time Data
Seaman, John C.
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The vadose zone is an area of ongoing concern because of its role in the fate and transport of chemicals resulting from waste disposal and agricultural practices. The degree of contamination and movement of solutes in soil solution are often difficult to assess due to temporal variability in precipitation or irrigation events and spatial variability in soil physical properties. For this reason, modeling groundwater and contaminant migration in unsaturated soil is crucial in determining the extent of the contamination. Unfortunately, manual methods used to sample soil pore water and validate model results are often inefficient due to the variable nature of the vadose system. Manual techniques are traditionally performed at arbitrary intervals without specific knowledge of the conditions in the soil at the time of sampling. This hit or miss approach can lead to missed samples, poor sample recovery, and samples that are not representative of the event of interest. In an effort to target specific soil conditions at the point of sampling that are conducive to successful sample acquisition, an automated lysimeter sampling and fraction collector system was developed. We demonstrate an innovative technique coupling real-time data with soil solution sampling methods which will improve the efficiency and accuracy of contaminant sampling in the field. The infrastructure of this system can also be implemented in a laboratory setting which adds to its practicality in characterizing soil hydraulic properties and model development.