Figure 2. A) total Fe and B) total Mn concentrations in FCR from 2020 until 2021. Total Fe and Mn concentrations are derived from manual samples that are collected approximately weekly during the summer stratified period each year. The HOx system was activated on 29 June 2020 and 11 June 2021 (solid black vertical lines) and deactivated on 02 December 2020 and 06 December 2021 (dashed black vertical lines). Values are linearly interpolated for plotting purposes. Inverted triangles at the top of the panel indicate sampling times.