Two questions

Dear EFDC team and users: I have 2 questions: 1.What does that means:diatoms (mg/L as c)? Diatom alge caculated by carbon? How to caculate? And why doesn’t the simulation change ? 2.What the real meaning of COD in EFDC? I heard that COD in EFDC is not the same meaning with that in china.And the simulation also doesn’t change…

  1. It is diatom algae concentration as Carbon. That quantity is measured by laboratory analysis using the ash-free dry weight method. It is not the same thing as the concentration of chl-a that you might get from a photometer, as that method can pick up the signal of pigments other than chl-a. I have attached a document regarding this which was published by the United States Geological Survey. Hopefully, this will be a helpful resource for you.2. You can find more information about the Chemical Oxygen Demand (COD) on our knowledge base here: that helps.

Thank you very much.I think this information will help me a lot.I’ll read it carefully