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The heterogeneous nature of Fe delivery from melting icebergs

M.J. Hopwood1,

1GEOMAR, Helmholtz Centre for Ocean Research, 24148 Kiel, Germany

C. Cantoni2,

2CNR-ISMAR, Marine Science Institute, 34149 Trieste, Italy

J.S. Clarke1,

1GEOMAR, Helmholtz Centre for Ocean Research, 24148 Kiel, Germany

S. Cozzi2,

2CNR-ISMAR, Marine Science Institute, 34149 Trieste, Italy

E.P. Achterberg1

1GEOMAR, Helmholtz Centre for Ocean Research, 24148 Kiel, Germany

Affiliations  |  Corresponding Author  |  Cite as  |  Funding information

Hopwood, M.J., Cantoni, C., Clarke, J.S., Cozzi, S., Achterberg, E.P. (2017) The heterogeneous nature of Fe delivery from melting icebergs. Geochem. Persp. Let. 3, 200–209.

European Commission (OCEAN-CERTAIN, FP7- ENV-2013-6.1-1; no: 603773)

Geochemical Perspectives Letters v3, n2  |  doi: 10.7185/geochemlet.1723
Received 27 September 2016  |  Accepted 25 April 2017  |  Published 7 June 2017

Figure 1 Surface fjord sample locations in Kongsfjorden.
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Figure 2 Median FeAsc (wt. %) with 25/75th (boxes) and 10/90th (whiskers) percentiles (outliers also shown) for iceberg embedded (n = 34) and iceberg surface (n = 20) sediment.
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Figure 3 DFe and TdFe (both nM, plotted as log10, TdFe shown minus DFe) for 28 discrete iceberg samples showed no clear relationship.
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Table 1 Comparing data for Kongsfjorden from this and prior work suggests a critical difference in both FeAsc (wt. %) and in the scaling of FeAsc to iceberg sediment load (g L-1 of ice melt).*The suggested 0.5 g L-1 sediment loading is used for data from Raiswell et al. (2016)

Raiswell, R., Hawkings, J.R., Benning, L.G., Baker, A.R., Death, R., Albani, S., Mahowald, N., Krom, M.D., Poulton, S.W., Wadham, J., Tranter, M. (2016) Potentially bioavailable iron delivery by iceberg-hosted sediments and atmospheric dust to the polar oceans. Biogeosciences 13, 3887–3900.

.** For our study, measured sediment loadings were used for each sample. As sediment-rich ice was specifically targeted, the calculated mean/median should be over-estimates.

a This studyb Raiswell et al. (2016)

Raiswell, R., Hawkings, J.R., Benning, L.G., Baker, A.R., Death, R., Albani, S., Mahowald, N., Krom, M.D., Poulton, S.W., Wadham, J., Tranter, M. (2016) Potentially bioavailable iron delivery by iceberg-hosted sediments and atmospheric dust to the polar oceans. Biogeosciences 13, 3887–3900.

a/b %
FeAsc / wt. %Mean0,0210,1416

FeAsc / µM (per litre of ice melt)*Mean<59 **12480

Median<2.5 **8,231
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Figure 4 FeAsc (µmol L-1 melted ice) increased with sediment load (g L-1 melted ice), but it is unclear if the relationship remains linear at high (>50 g L-1) loadings.
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Supplementary Figures and Tables

Table S-1 Analysis of Certified Reference Materials for Fe concentration (± standard deviation of at least 6 measurements).
Certified Reference MaterialFe (± SD) / nMCertified Fe concentration / nM
NASS-76.21 (± 0.77)6.29 (± 0.47)
CASS-626.6 (± 0.71)27.9 (± 2.1)
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Table S-2 FeAsc concentration reported for various sediment samples collected around Kongsfjorden. For iceberg embedded sediment with sediment loadings >0.1 g L-1, FeAsc is reported both as wt. % and per volume of meltwater.
Sample numberOriginFeAsc wt. %*FeAsc µmol / L*Sediment loading g / L
1Embedded sediment , glacier crevasse (Midtre Lovénbreen)0.014
2Embedded sediment , glacier crevasse (Midtre Lovénbreen)0.0057
3Embedded sediment , glacier crevasse (Midtre Lovénbreen)0.17
4Embedded sediment , glacier crevasse (Midtre Lovénbreen)0.023
5Embedded sediment , glacier crevasse (Midtre Lovénbreen)0.0038
6Embedded sediment , glacier crevasse (Midtre Lovénbreen)0.053
7Glacier surface sediment (Kongsvegen)0.016
8Glacier surface sediment (Kongsvegen)0.016
9Glacier surface sediment (Kongsvegen)0.012
10Glacier surface sediment (Kongsvegen)0.010
11Glacier surface sediment (Kongsvegen)0.016
12Glacier surface sediment (Kongsvegen)0.012
13Glacier surface sediment (Kongsvegen)0.014
14Iceberg embedded sediment0.00911069
15Iceberg embedded sediment0.00933420
16Iceberg embedded sediment0.00769066
17Iceberg embedded sediment0.00745239
18Iceberg embedded sediment0.00851711
19Iceberg embedded sediment0.0162.50.91
20Iceberg embedded sediment0.00891.20.76
21Iceberg embedded sediment0.0853.90.25
22Iceberg embedded sediment0.0149.63.9
23Iceberg embedded sediment0.020820230
24Iceberg embedded sediment0.0343.90.65
25Iceberg embedded sediment0.0112613
26Iceberg embedded sediment0.0261000230
27Iceberg embedded sediment0.0239623
28Iceberg embedded sediment0.00423850
29Iceberg embedded sediment0.02216041
30Iceberg embedded sediment0.01611038
31Iceberg embedded sediment0.00823121
32Iceberg embedded sediment0.0245212
33Iceberg embedded sediment0.009511065
34Iceberg embedded sediment0.00739170
35Iceberg embedded sediment0.0155.01.8
36Iceberg embedded sediment0.013177.5
37Iceberg embedded sediment0.011340170
38Iceberg embedded sediment0.0277.81.6
39Iceberg embedded sediment0.0261.20.25
40Iceberg embedded sediment0.025112.4
41Iceberg embedded sediment0.123.00.14
42Iceberg embedded sediment0.0282.50.51
43Iceberg embedded sediment0.013198.1
44Iceberg embedded sediment0.0118039
45Iceberg embedded sediment0.0203.60.99
46Iceberg embedded sediment0.0261.20.26
47Iceberg embedded sediment0.0122.11.0
48Iceberg embedded sedimentn/d0.26< 0.1
49Iceberg embedded sedimentn/d0.26< 0.1
50Iceberg embedded sedimentn/d0.87< 0.1
51Iceberg embedded sedimentn/d0.65< 0.1
52Iceberg embedded sedimentn/d0.27< 0.1
53Iceberg embedded sedimentn/d0.50< 0.1
54Iceberg embedded sedimentn/d0.28< 0.1
55Iceberg embedded sedimentn/d0.63< 0.1
56Iceberg embedded sedimentn/d0.40< 0.1
57Iceberg embedded sedimentn/d0.69< 0.1
58Iceberg embedded sedimentn/d0.37< 0.1
59Iceberg embedded sedimentn/d0.43< 0.1
60Iceberg embedded sedimentn/d0.68< 0.1
61Iceberg embedded sedimentn/d0.87< 0.1
62Iceberg embedded sedimentn/d0.27< 0.1
63Iceberg embedded sedimentn/d0.39< 0.1
64Iceberg embedded sedimentn/d1.8< 0.1
65Iceberg embedded sedimentn/d0.40< 0.1
66Iceberg embedded sedimentn/d0.77< 0.1
67Iceberg embedded sedimentn/d0.35< 0.1
68Iceberg embedded sedimentn/d0.29< 0.1
69Iceberg embedded sedimentn/d0.32< 0.1
70Iceberg embedded sedimentn/d0.20< 0.1
71Iceberg embedded sedimentn/d0.15< 0.1
72Iceberg surface sediment0.0065
73Iceberg surface sediment0.0068
74Iceberg surface sediment0.0091
75Iceberg surface sediment0.0072
76Iceberg surface sediment0.024
77Iceberg surface sediment0.0071
78Iceberg surface sediment0.032
79Iceberg surface sediment0.010
80Iceberg surface sediment0.012
81Iceberg surface sediment0.021
82Iceberg surface sediment0.0093
83Iceberg surface sediment0.0077
84Iceberg surface sediment0.059
85Iceberg surface sediment0.0066
86Iceberg surface sediment0.0080
87Iceberg surface sediment0.0080
88Iceberg surface sediment0.029
89Iceberg surface sediment0.032
90Iceberg surface sediment0.0087
91Iceberg surface sediment0.0098
92Pro-glacial stream, glacial flour0.0090
93Pro-glacial stream, glacial flour0.0083
94Pro-glacial stream, glacial flour0.0063
95Pro-glacial stream, glacial flour0.0079
96Pro-glacial stream, glacial flour0.0072
97Pro-glacial stream, glacial flour0.0070
98Pro-glacial stream, glacial flour0.0073
99Pro-glacial stream, glacial flour0.019
100Pro-glacial stream, glacial flour0.031
101Pro-glacial stream, glacial flour0.010
102Pro-glacial stream, glacial flour0.0078
103Pro-glacial stream, glacial flour0.010
104Pro-glacial stream, glacial flour0.0066
105Pro-glacial stream, glacial flour0.0089
106Pro-glacial stream, glacial flour0.0096
107Pro-glacial stream, glacial flour0.0041
108Pro-glacial stream, glacial flour0.0032
109Pro-glacial stream, glacial flour0.0057
110Pro-glacial stream, glacial flour0.0079
111Surface glacier (Kongsvegen) embedded sediment0.044
112Surface glacier (Kongsvegen) embedded sediment0.071
113Surface glacier (Kongsvegen) embedded sediment0.037
114Surface glacier (Kongsvegen) embedded sediment0.011
115Surface glacier (Kongsvegen) embedded sediment0.061
116Surface glacier (Kongsvegen) embedded sediment0.11

* Iceberg embedded sediment only
n/d not determined as dry mass insufficient (<0.1 g)

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Table S-3 Dissolved (<0.2 µm) Fe and total dissolvable Fe for 15 surface water samples collected in Kongsfjorden (July 2015).
NameDFe / nMTdFe / nMTemperature / °CLatitude °NLongitude °ESalinity
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Table S-4 Dissolved (<0.2 µm) Fe and total dissolvable Fe for 28 randomly collected Kongsfjorden iceberg samples (July 2015).
Sample labelOriginCatchmentDFe / nMTdFe / nMPFe (TdFe-DFe) / nM
Ice 1Ny Alesund, Svalbard, Summer 2015Kongsfjorden19.2261242
Ice 2Ny Alesund, Svalbard, Summer 2015Kongsfjorden9.59787
Ice 3Ny Alesund, Svalbard, Summer 2015Kongsfjorden1.3369367
Ice 4Ny Alesund, Svalbard, Summer 2015Kongsfjorden7.910131005
Ice 5Ny Alesund, Svalbard, Summer 2015Kongsfjorden4.9331326
Ice 6Ny Alesund, Svalbard, Summer 2015Kongsfjorden0.6133133
Ice 7Ny Alesund, Svalbard, Summer 2015Kongsfjorden3.2377374
Ice 8Ny Alesund, Svalbard, Summer 2015Kongsfjorden2.0109107
Ice 9Ny Alesund, Svalbard, Summer 2015Kongsfjorden2.15452
Ice 10Ny Alesund, Svalbard, Summer 2015Kongsfjorden6.4897890
Ice 11Ny Alesund, Svalbard, Summer 2015Kongsfjorden16.522742257
Ice 12Ny Alesund, Svalbard, Summer 2015Kongsfjorden6.6470464
Ice 13Ny Alesund, Svalbard, Summer 2015Kongsfjorden9.72325923250
Ice 14Ny Alesund, Svalbard, Summer 2015Kongsfjorden8.0221213
Ice 15Ny Alesund, Svalbard, Summer 2015Kongsfjorden3.74945
Ice 16Ny Alesund, Svalbard, Summer 2015Kongsfjorden3.95955
Ice 17Ny Alesund, Svalbard, Summer 2015Kongsfjorden11.16251
Ice 18Ny Alesund, Svalbard, Summer 2015Kongsfjorden9.54637
Ice 19Ny Alesund, Svalbard, Summer 2015Kongsfjorden12.46553
Ice 20Ny Alesund, Svalbard, Summer 2015Kongsfjorden5.47973
Ice 21Ny Alesund, Svalbard, Summer 2015Kongsfjorden536.35740156864
Ice 22Ny Alesund, Svalbard, Summer 2015Kongsfjorden54.77722
Ice 23Ny Alesund, Svalbard, Summer 2015Kongsfjorden4.1156151
Ice 24Ny Alesund, Svalbard, Summer 2015Kongsfjorden1.49997
Ice 25Ny Alesund, Svalbard, Summer 2015Kongsfjorden1.4107106
Ice 26Ny Alesund, Svalbard, Summer 2015Kongsfjorden3.48884
Ice 27Ny Alesund, Svalbard, Summer 2015Kongsfjorden16.5830814
Ice 28Ny Alesund, Svalbard, Summer 2015Kongsfjorden266.11087610610
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