3.2 Water column dissolved Cr sampling
IN2018_V02, IN2018_V04, and GP13 samples were collected using an
autonomous trace metal clean rosette system and gravity filtered through
acid-cleaned 0.2 µm filters (Pall Acropak) into acid cleaned LDPE
bottles in a class 100 clean van. IN2018 samples were acidified to pH
< 2 (2 mL L-1 sub-boiling distilled
concentrated HCl) on land and stored for 3-26 months before analysis.
GP13 samples were stored frozen until 2019, at which point they were
thawed, acidified as for IN2018 samples, and stored at least 7 months
before analysis. DY110 samples were collected with a conventional
CTD-rosette, gravity filtered through acid-cleaned 0.2 µm filters (Pall
Acropak) acidified to pH ≈ 2 (1 mL L-1 concentrated
HCl), and stored for at least 3 months before analysis. Sampling and
sample handling are discussed in detail elsewhere for ACE (Rickli et
al., 2019), M77/4 (Nasemann et al., 2020) and Line P (Janssen & Cullen,
2015).