Question about contamination scenario


Hello everyone,
Articles for generating contamination scenarios usually consider the source, duration and magnitude of injection randomly. But articles do not explain how to select these items and these values ​​should be selected in what range.
If a node is selected as the source of injection, then, Usually the concentration of contamination is how many milligrams per liter?

In general, what should be the duration, the amount and the concentration?

If anyone has an article in this regard, I’d be so happy to introduce it to me.