Table 2.
Average characteristics of solid-phase extracted dissolved organic matter (SPE-DOM) within the original plume sample and post incubation.
| Sample | m/z | H/C | O/C | AImod | DBE | NOSC | IDEG¥ | #Form | DF(C)○ | DF(H/C)○ | DF(NOSC)○ | #Fe–Form |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| [–] | [–] | [–] | [–] | [–] | [–] | [–] | [–] | [–] | [–] | [–] | [–] | |
| Plume sample (P) | 407 | 1.28 | 0.45 | 0.237 | 8.13 | − 0.34 | 0.76 | 1722 | 2.19 | 0.080 | 0.160 | 94 |
| Initial solution 50:450 (P:C)** | 297 | 1.40 | 0.34 | 0.243 | 5.83 | − 0.66 | 0.29 | – | 2.54 | 0.162 | 0.246 | – |
| Post incubation samples | ||||||||||||
| Control (C) I | 280 | 1.40 | 0.31 | 0.255 | 5.57 | – | – | 436 | – | – | – | – |
| Control (C) II | 265 | 1.46 | 0.29 | 0.231 | 5.00 | – | – | 382 | – | – | – | – |
| Control (C) III | 268 | 1.43 | 0.30 | 0.247 | 5.23 | – | – | 365 | – | – | – | – |
| Inc 0 µM Fe I | 415 | 1.27 | 0.46 | 0.235 | 8.30 | – | – | 1820 | – | – | – | – |
| Inc 0 µM Fe II | 414 | 1.27 | 0.46 | 0.235 | 8.26 | – | – | 1801 | – | – | – | – |
| Inc 0 µM Fe III | 415 | 1.28 | 0.46 | 0.235 | 8.28 | – | – | 1810 | – | – | – | – |
| Inc 0.1 µM Fe I | 414 | 1.28 | 0.46 | 0.235 | 8.26 | – | – | 1809 | – | – | – | – |
| Inc 0.1 µM Fe II | 409 | 1.28 | 0.45 | 0.237 | 8.17 | – | – | 1747 | – | – | – | – |
| Inc 0.1 µM Fe III (†) | 373 | 1.29 | 0.42 | 0.257 | 7.61 | – | – | 1226 | – | – | – | – |
| Inc 1 µM Fe I | 398 | 1.28 | 0.44 | 0.242 | 8.04 | – | – | 1464 | – | – | – | – |
| Inc 1 µM Fe II | 396 | 1.28 | 0.44 | 0.243 | 8.00 | – | – | 1513 | – | – | – | – |
| Inc 1 µM Fe III | 393 | 1.30 | 0.42 | 0.244 | 7.88 | – | – | 1585 | – | – | – | – |
| Inc 10 µM Fe I (†) | 411 | 1.27 | 0.47 | 0.237 | 8.27 | – | – | 1771 | – | – | – | – |
| Inc 10 µM Fe II | 380 | 1.29 | 0.42 | 0.251 | 7.72 | – | – | 1334 | – | – | – | – |
| Inc 10 µM Fe III | 367 | 1.30 | 0.40 | 0.258 | 7.53 | – | – | 1218 | – | – | – | – |
| Inc 100 µM Fe I (†) | 354 | 1.30 | 0.39 | 0.265 | 7.33 | – | – | 1237 | – | – | – | – |
| Inc 100 µM Fe II | 386 | 1.29 | 0.43 | 0.248 | 7.83 | – | – | 1403 | – | – | – | – |
| Inc 100 µM Fe III | 379 | 1.29 | 0.42 | 0.251 | 7.72 | – | – | 1354 | – | – | – | – |
| Inc 1 mM Fe I (‡) | 411 (‡) | 1.28 | 0.46 | 0.237 | 8.25 | – | – | 1799 | – | – | – | – |
| Inc 1 mM Fe II (‡) | 364 (‡) | 1.31 | 0.39 | 0.258 | 7.47 | – | – | 1366 | – | – | – | – |
| Inc 10 mM Fe I | 355 | 1.31 | 0.39 | 0.263 | 7.34 | – | – | 1187 | – | – | – | – |
| Inc 10 mM Fe II | 361 | 1.31 | 0.39 | 0.261 | 7.43 | – | – | 1282 | – | – | – | – |
| Inc 10 mM Fe III (•) | 402 (‡) | 1.28 | 0.45 | 0.240 | 8.07 | – | – | 1679 | – | – | – | – |
| Averages for triplicates with DOM characteristics of the reduced dataset (section = only formulae occurring in all replicates)* | ||||||||||||
| Control (C) section | 267 | 1.43 | 0.30 | 0.245 | 5.20 | − 0.75 | – | 317 | 2.64 | 0.185 | 0.269 | 7 |
| 0 µM Fe section | 414 | 1.27 | 0.46 | 0.235 | 8.28 | − 0.31 | 0.80 | 1794 | 2.18 | 0.083 | 0.168 | 117 |
| 0.1 µM Fe section | 411 | 1.28 | 0.46 | 0.236 | 8.22 | − 0.32 | 0.79 | 1741 | 2.20 | 0.082 | 0.166 | 98 |
| 1 µM Fe section | 394 | 1.28 | 0.44 | 0.244 | 7.97 | − 0.38 | 0.74 | 1403 | 2.29 | 0.081 | 0.157 | 28 |
| 10 µM Fe section | 372 | 1.30 | 0.41 | 0.255 | 7.60 | − 0.45 | 0.67 | 1197 | 2.43 | 0.093 | 0.162 | 11 |
| 100 µM Fe section | 381 | 1.29 | 0.42 | 0.250 | 7.76 | − 0.42 | 0.69 | 1309 | 2.37 | 0.087 | 0.158 | 14 |
| 10 mM Fe section | 357 | 1.30 | 0.39 | 0.263 | 7.38 | − 0.50 | 0.61 | 1172 | 2.54 | 0.101 | 0.167 | 8 |
| NEqPIW section (N = 5) | 424 | 1.28 | 0.45 | 0.235 | 8.42 | − 0.33 | 0.84 | 1527 | 2.30 | 0.079 | 0.158 | – |
Values for the 50:450 (P:C) initial solution were calculated from SPE-DOC weighed average characteristics (see Table 1). Average mass of formulae (m/z); elemental ratios (H/C, O/C); average modified aromaticity (AImod); double bond equivalent (DBE) after Koch and Dittmar (2006, 2017); North Equatorial Pacific Intermediate Water (NEqPIW)—in-house standard.
†Excluded from the evaluation of DOM as SPE-TDN exceeds TDN indicating contamination (see Table 1).
‡Excluded as number of sequences too low for microbial community analysis (see Table 1) and DOM of replicates is inconclusive.
•Excluded from further evaluation of DOM as an outlier as both other replicates are in very good agreement.
*Reduced dataset refers to further evaluation of DOM after exclusion of specific incubations (†, ‡ and •).
**Values for the 50:450 (P:C) initial solution were calculated from plume and control end members.
¥IDEG of initial solution 50:450 (P:C) based on weighted intensities of control (9×) and plume sample (1×).
○Diversity indices used by Mentges et al.42; DA Gini-Simpson index; DF(C, H/C, NOSC) Rao's entropy—functional diversity.