Response to comments by Anonymous Referee #1

Abstract

First, we wish to thank the reviewer for his/her valuable inputs and comments on our manuscript. L39-40: I'm surprised there are no older references to the role of iron. Reply: We agree that indeed there are many more references regarding the role of iron in the environment. However, our choice can be considered as "best of" selection, covering a whole suite of different aspects: We choose (1) Expert et al., 2012 since C1