I do, certainly. As I said, there are so many mechanisms by which contaminated groundwater can be transferred.
The easiest example to understand is that if you put any contaminant in water, it moves with the water. That's an advective transport. Groundwater doesn't behave like that, because it goes through pores or fractures. So in addition to advective transport, you have to add molecular diffusion.... I don't know if I have time to explain this, but it's very complicated...from the ion exchange to rock.
Don't forget that groundwater may change the geology and vice versa. The rocks may affect groundwater. Sometimes you need to separate natural phenomena versus anthropogenic phenomena.
I concur with what he said. It's very difficult.