What is shown on this graph?

It shows transient storage. X-axis: Time after tracer release (in minutes). Y-axis: Concentration of the tracer (RWT, or Rhodamine WT dye) in parts per billion (ppb). The shape of the curve shows how the tracer moves through the system: Initial rise (blue arrow): The tracer enters the main channel and begins dispersing downstream. Prolonged tail (pink arrow): Tracer is slowly released back from storage zones, creating a delayed decline in concentration over time. Left side figure. Its a model showing the fow in a channel. The water that is flowing some of it is moving into storage stays there for a while and moves out again into the channel. The storage area/capacity You can get how much water goes into the transient area by putting salt into the system. If there was no transient storage it would follow the black line. K1 is the blue pil and the purple arrow tells something about k2. something about how fast (dont think we have to know this. Just if its a hsort tail or long tail.