Supplementary Material

Identifying the sources and sinks of CDOM/FDOM across the

Mauritanian Shelf and their potential role

in the decomposition of Superoxide (O2-)

Authors: Maija, I. Heller1,2, * Kathrin Wuttig1,3 and Peter L. Croot1,4

1Marine Biogeochemistry, GEOMAR Helmholtz Centre for Ocean Research Kiel,

Duesternbrooker Weg 20, 24105 Kiel, Germany

2Department of Ocean Sciences, University of California, Santa Cruz, CA, United States,

maija.heller@gmail.com

3Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania,

Private Bag 80, Hobart Tasmania 7001, Australia, kathrin.wuttig@utas.edu.au

4Earth and Ocean Sciences, School of Natural Sciences, National University of Ireland

Galway (NUIG), peter.croot@nuigalway.ie

Comprising:

9 Pages

5 Tables

1 Figure

* Corresponding Author: maija.heller@gmail.com

Table S1: Location of the trace metal clean sampled Goflo stations of this present study

Stn.Sampling

gear Nr. Date Time Coord. Coord.Bot.

depthMSM17-4 2011 (UTC) Lat. ºN Long. °W (m)

336 GOFLO 1 13.03. 22:34 12°49,990 17°33,850 53352 GOFLO 2 15.03. 00:03 13°59,927 17°37,473 981356 GOFLO 3 15.03. 09:03 14°00,187 17°24,004 81382 GOFLO 4 18.03. 12:42 16°11,500 16°52,004 236404 GOFLO 5 20.03. 06:24 18°15,299 16°27,001 95454 GOFLO 6 24.03. 16:35 18°12,454 16°35,598 417456 GOFLO 7 24.03. 18:20 18°12,453 16°35,598 418491 GOFLO 8 29.03. 08:34 18°11,302 16°39,302 786493 GOFLO 9 29.03. 15:00 18°11,301 16°39,302 786514 GOFLO 10 01.04. 09:26 18°11,301 16°39,299 786517 GOFLO 11 01.04. 16:29 18°11,252 16°39,274 791525 GOFLO 12 03.04. 09:57 18°09,999 16°45,009 1111527 GOFLO 13 03.04. 13:26 18°10,056 16°45,022 1115541 GOFLO 14 05.04. 06:10 18°13,099 16°33,309 240543 GOFLO 15 05.04. 08:32 18°13,040 16°33,346 245592 GOFLO 16 09.04. 09:25 20°20,000 17°45,011 592

Table S2: Duration of the O2- experiments which used the thermal O2

- source SOTS-1 (di(4-

carboxybenzyl) hyponitrite) which generate O2− at µM and continuously over several hours

(Heller and Croot, 2010a).

Goflo Stn [SOTS-1]0 in µM Exp Duration in h

5 1.78 23

6 1.78 10

7 1.67 10

8 0.86 9

9 1.56 10

10&11 No O2- Exp

12 1.5 9

13 1.5 8

14 1.71 6

Table S3: MSM17-4 distribution of FDOM components identified by PARAFAC

Station Depth C1 [RFU] C2 [RFU] C3 [RFU]5 30 0.023 0.013 0.0155 45 0.022 0.013 0.0115 63 0.024 0.012 0.014

6 20 0.025 0.015 0.0206 40 0.025 0.014 0.0126 60 0.031 0.013 0.0186 80 0.030 0.012 0.0217 105 0.024 0.011 0.0107 180 0.022 0.011 0.0057 280 0.022 0.011 0.0077 355 0.024 0.013 0.012

8 25 0.021 0.011 0.0168 50 0.025 0.012 0.0118 100 0.027 0.011 0.0208 200 0.023 0.011 0.0099 300 0.022 0.011 0.0069 400 0.025 0.012 0.0139 550 0.025 0.012 0.0099 700 0.022 0.012 0.009

12 20 0.020 0.012 0.00312 40 0.022 0.011 0.00412 100 0.022 0.011 012 200 0.020 0.010 013 300 0.020 0.011 0.03313 400 0.023 0.012 013 600 0.019 0.012 0.00913 800 - - -

14 20 0.040 0.018 0.00714 40 0.024 0.013 0.01014 70 0.029 0.011 0.00714 100 0.030 0.012 0.02215 170 0.029 0.014 0.01715 190 0.033 0.011 0.015

Table S4: MSM17-4 Superoxide decay rates using SOTS-1 as superoxide source

Station Depth kDTPA kSW

5 30 0.0052 ± 0.0023 0.0086 ± 0.00365 45 0.0071 ± 0.0035 0.0129 ± 0.00595 63 0.0066 ± 0.0032 0.0127 ± 0.0062

6 20 0.0067 ± 0.0023 0.0119 ± 0.00386 40 0.0064 ± 0.0021 0.0097 ± 0.00386 60 0.0053 ± 0.0023 0.0092 ± 0.00356 80 0.0058 ± 0.0026 0.0104 ± 0.00447 105 0.0034 ± 0.0007 0.0099 ± 0.00267 180 0.0059 ± 0.0030 0.0100 ± 0.00247 280 0.0045 ± 0.0017 0.0110 ± 0.00127 355 0.0049 ± 0.0019 0.0099 ± 0.0024

8 25 0.0121 ± 0.0031 0.0167 ± 0.00348 50 0.0169 ± 0.0053 0.0241 ± 0.00728 100 0.0135 ± 0.0045 0.0169 ± 0.00478 200 0.0137 ± 0.0018 0.0207 ± 0.00159 300 0.0097 ± 0.0024 0.0158 ± 0.00449 400 0.0085 ± 0.0034 0.0157 ± 0.00529 550 0.0054 ± 0.0024 0.0114 ± 0.00409 700 0.0067 ± 0.0029 0.0122 ± 0.0045

12 20 0.0098 ± 0.0057 0.0132 ± 0.006712 40 0.0111 ± 0.0069 0.0152 ± 0.008512 100 0.0114 ± 0.0070 0.0210 ± 0.009212 200 0.0114 ± 0.0072 0.0215 ± 0.011613 300 0.0071 ± 0.0013 0.0132 ± 0.001713 400 0.0091 ± 0.0019 0.0140 ± 0.003013 600 0.0072 ± 0.0018 0.0096 ± 0.002313 800 0.0098 ± 0.0020 0.0122 ± 0.0028

14 20 0.0079 ± 0.0016 0.0119 ± 0.003214 40 0.0079 ± 0.0005 0.0108 ± 0.001414 70 0.0071 ± 0.0013 0.0090 ± 0.000914 100 0.0084 ± 0.0006 0.0147 ± 0.002515 170 0.0079 ± 0.0005 0.0170 ± 0.001915 190

Data is reported as ±1 sd.

Table S5. 2nd Order Reaction Rate Constants (M-1 s-1) for selected metal and organic species with O2

- modified after (Heller and Croot, 2010b). Species HO2 O2

-

Cu(I) > 1*109 (a) ~1*1010 (a)

- 9.4±0.8*109 (b)

- 1.98±0.05*109 (c)

Cu(II) 1.2*108 (d) 1.1*1010 (d)

- 6.63 ± 0.71*108 (c)

Fe(II) 1.2±0.5*106 (e) 7.2*108 (f)

1.2±0.2*106 (g) 1.0±0.1*107 (g)

Fe(III) - 1.8*108 (g)

Mn(II)

Mn(III)

3.1*105 (h) 1.5±0.2*108 (i)

5.4*107 (j)

2.8*107 (k)

1.7*107 (l)

8.9*106 (m)

HO2 8.3±0.7*105 (n) 9.7±0.6*107 (n)

Cu(II)L - 2.9-8.1*108 (o)

- 5±3*107 (p)

Fe(III)L - 9.3±0.2*103 (q)

- 2.3±0.1*105 (r)

Ferulic acid

Gallic acid

Cinnamic acid

Caffeic acid

1.6*105 (s)

5.4*106 (s)

5.9*103 (s)

5.0*105 (s)

Notes: The reader is also referred to the compilation of Bielski et al. (1985). In describing the

experimental setup used in each work we use the following abbreviations: pulse radiolysis (p.r.), flash

photolysis (f.p.), irradiation (γ-r), optical detection of superoxide (opt) and chemical detection of

superoxide or equivalent (chem.). The pKa for HO2 is 4.60±0.15 (Zafiriou, 1990). All experiments are

in the range 20-25° C.

(a)Cu+, pH 5.3, p.r. opt. (Rabani et al., 1973). (b)Cu+, p.r. opt. (Piechowski von et al., 1993). (c)Cu+ and Cu++ in

seawater, p.r. opt. (Zafiriou et al., 1998). (d)Cu2+ and Cu2+-arginine, p.r, opt.(Cabelli et al., 1987). (e)Fe2+, pH 1, p.r,

opt.(Jayson et al., 1973). (f)Fe2+ and Fe3+, p.r., opt (Matthews, 1983). (g)Fe2+ species, pH 1-7, p.r, opt (Rush and

Bielski, 1985). (h)Fe3+ species, pH 2.74, p.r., opt (Sehested et al., 1969). (i)Fe(OH)2+ species, pH 1-7, p.r, opt

(Rush and Bielski, 1985). (j) Mn+ in sulphate, pH 7, γ-r, opt (Barnese et al., 2008). (k) Mn+ in phosphate, pH 7, γ-r,

opt(Barnese et al., 2008). (l) Mn+ in pyrophosphate, pH 7, γ-r, opt(Barnese et al., 2008). (m)Mn3+ in phosphate,

pH 7, γ-r, opt(Barnese et al., 2008). (n)As summarized in Bielski et al. (1985). (o)Natural seawater with Cu

complexing ligands (Voelker et al., 2000). (p)Copper complexing ligands produced by Synechococcus (Voelker

et al., 2000). (q)Fe(III) complexed with desferrioxamine B in bicarbonate buffered solution (Rose and Waite,

2005). (r)Fe(III) complexed with natural organic matter in bicarbonate buffered solution (Rose and Waite, 2005).

(s) Values from Taubert (2003)

Figure S1: Spectral characteristics of 3-component model for MSM17-4 dataset (N=253). Highest intensities are shown in yellow.

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