I recently learned that black walnut trees can be tapped to make syrup, similar to maple trees. I have a bunch on my property and that sounds like a really cool idea...but I also live within the area of the Gelman 1,4-dioxane plume. Is it safe to collect sap from my trees, or might it be contaminated? Factors I can think of that enter into the equation:

1. Is the contamination present in surface water, or only in subsurface groundwater? How deep?
2. How deep do the tree roots reach in comparison?
3. Do the trees readily uptake 1,4-dioxane from the soil and incorporate it in their sap?

Has any end-to-end research/testing been done on this (i.e. actually making maple/walnut/etc syrup in a contaminated area and testing the result)? If not, unless the answers to the above essentially rule out contamination as a concern, would it be possible to have such testing done at an affordable price (<$100 or so), or might there be any research groups interested in doing so and able to fund it?