Single Well Injection Test - Natural Gradient

A diagram of a natural gradient, single well injection test that can be used to estimate the rate that hydrogen is consumed by bacteria in the subsurface. Step 1 of the test involves the controlled injection of a solution of dissolved hydrogen gas and a non-reactive tracer using a single port of a multilevel monitoring well. Step 2 involves the collection of water-quality samples from the plume of hydrogen and tracer as it drifts past the same well.