<rahmann et al. 
SFB 754 cruises 2012-2015 
a I 7 a "OF — a— 
-M90 
M91 
mo2 kl] 
— —_mo3 
— SO241 
SO243 
3° 
5°5 
‚2°5 
18°5 
24°S | V 
a. 
30°W 85°W 80°W 75°W 
zu — At —] 
70°W 65°W 
FIGURE 6 | Cruise tracks of six SFB 754 cruises in the Pacific in the second 
fundina period of the project 2012-2015} 
Oxide (MEMENTO)*° database as well as on PANGAEA 
(Arevalo-Martinez and Mehrtens, 2021; see Table 2 and 
Supplementary Table 13). 
Trace Chemical Species 
Trace metal clean sampling equipment was deployed on a sub-set 
of cruises (see Croot et al., 2021; see Table 2 and Supplementary 
Table 14) to facilitate the observation of contamination prone 
chemical parameters. 
All trace metal sample collection, handling, and analysis was 
conducted in accordance with GEOTRACES protocols which 
have been updated through the SFB 754 program (Cutter 
at al., 2014). All cruises with trace metal work (Supplementary 
Table 14) deployed an overpressurized clean container on deck to 
process contamination-prone samples at sea, except cruise M92 
where sample handling was undertaken underneath laminar flow 
hoods. For cruises from 2008 to 2013, PTFE-coated 8 1 GO-FLO 
bottles (General Oceanics) were mounted on a Kevlar wire with 
sample handling and preservation as per Chever et al. (2015). 
From 2014 onward, 24 Ocean Test Equipment (OTE) samplers 
were deployed mounted on a powder coated sampling CTD (Sea- 
Bird SBE25) rosette using a Kevlar conducting cable with sample 
handling and preservation as per Rapp et al. (2019). 
Prior to 2014, dissolved trace metal concentrations were 
largely determined by graphite furnace atomic absorption 
spectroscopYy after offline pre-concentration as per Schlosser et al. 
'https://memento.geomar.de/ 
-rontiers in Marine Science | www. frontiersin.orm 
SFB754 Data Legacy 
SFB 754 cruises 2016-2019 
LA za 
——. 
- -M135 
M136 
—M137 
:M1238 
0° 
B6°S 
9° 
8°S 
LAN 
. MM 
90°W 85°W 80°W 75°W 70°W 65°W 
FIGURE 7 | Cruise tracks of four SFB 754 cruises in the Pacific in the third 
funding period of the project 2016-2019}. 
(2018) with calibration of all elements via standard addition. 
Post 2014, dissolved trace metal samples were analyzed via 
[nductively Coupled Plasma Mass Spectrometry after offline pre- 
concentration using a SeaFAST system exactly as per Rapp et al. 
(2017). A number of trace metal isotopes were also analyzed with 
forthcoming data sets expected to expand the limited available 
isotopic data for the Peruvian OMZ with analysis as per Chever 
at al. (2015) for Fe and Xie et al. (2019) for Cd. 
In addition to dissolved trace metal concentrations, a number 
of redox sensitive trace species were quantified. These included 
Fe(II) and H,O, concentrations determined using flow injection 
analysis (Schlosser et al., 2018; Croot et al., 2019), and other 
reactive oxygen species as per Wulttig et al. (2013). Metal- 
speciation was also explored through titrations to characterize 
metal-ligand interactions with analytical methods as per Baars 
and Croot (2015) for Co species, and Gledhill and Van Den Berg 
(1994) for Fe(III) species. 
Biological Oceanography 
Pelagic biological field work of varying extent was carried 
out during most cruises. Topics spanned from marine 
biogeochemistry and microbiology to zooplankton and 
nekton ecology, and methods included field observations as 
well as on-board incubations for microbial as well as metazoan 
metabolic rate determination and large-scale experimental 
set-ups with various treatments such as bioassays, shipboard 
mesocosms, and a mesocosm experiment off Callao using 
the KOSMOS system. 
Zeptember 2021 | Volume 8 | Article 72820