PI: George Luther and Brent Lewis dataset: Iodine speciation cruise: TN045, Arabian Sea Process cruise #2 ship: R/V Thomas Thompson Methodology: Iodide, total iodine COLLECTION Samples were collected from routine hydrocasts and 0.45 micron (Gelman Supor membrane) filtered prior to analyses. Care was taken to draw samples after the dissolved oxygen reagents were removed from the hydrolab to avoid any potential sources of contamination during sampling. ANALYSES Iodide and iodate concentrations were determined using polarographic and voltammetric methods. Iodide (I-) was measured using cathodic stripping square wave voltammetry (CSSWV) [Luther et. al., 1988]. Iodate (IO3-) was measured using differential pulse polarography (DPP) [Herring and Liss, 1974]. Total iodine (...Ired) was measured using CSSWV [Campos (in press)]. Total iodine (...Iox) was measured using method of Takayanagi and Wong, 1986 following sample oxidation with 0.2% NaOCl. The instrument minimum detection limits in seawater for I-, IO3-, ...Iox and ...Ired using polarography are 0.2, 20, 20, and 5 nM respectively. Total iodine methodologies gave statistically equivalent values and are therefore simply reported as Tot_I. For detailed comparisons please consult (Farrenkopf,1997 -- Dissertation University of Delaware). Precision for iodide based upon triplicate measurements of individual samples is within 5-10% in samples greater than 200 nM and within 1-2% for iodide concentrations less than 200 nM. Method precisions in 3.5% NaCl were +/- 1%. Precisions for the total methods tend to vary significantly from sample to sample and so reported errors "stdev Tot_I" reflect the standard deviation of at least three replicates with three distinct standard addition curves (n>3). EQUIPMENT Electrochemical measurements were made in 10 mL glass polarographic cells. EG & G Princeton Applied Research model 384 B polarographic analyzers equipped with 303A hanging mercury drop working electrode (HDME) stands were used throughout. Potentials were measured vs. a saturated calomel reference electrode (SCE). A platinum counter electrode was used for current measurements in a standard three electrode voltammetric arrangement. Iodide gives rise to a peak at a potential of -0.306 V, and iodate has a peak potential of -1.08 V. Aboard ship 10.0 mL aliquots of sample were dispensed into glass voltammetric cells and purged of dissolved oxygen with ultra pure nitrogen gas. The concentrations of iodine species were determined by the method of standard addition. A minimum of three standard additions were made for each determination. Tot_I measurements were also made with an Analytical Instrument Systems (AIS) DLK-100 with version 3.4 software equipped with a 303A hanging mercury drop working electrode (HDME) stand. The analyses on the DLK-100 were the same as with the 384B (Luther et al., 1988) with the exception that the frequency was 200 Hz (as compared to 100 Hz on the 384B). References: Campos, M.L.A. (in press) New approach to evaluating dissolved iodine speciation in natural waters using cathodic stripping voltammetry. Marine Chemistry Luther, G. W., III, C. Branson Swartz and W.J. Ullman (1988) Direct determination of iodide in seawater by cathodic stripping square wave voltammetry. Analytical Chemistry. 60: 1721-1724. Luther, G.W., III (1991) Sulfur and iodine speciation in the water column of the Black Sea, in Black Sea Oceanography, E. Izdar and J. W. Murray, Editors. Kluwer Publishers: Netherlands. p. 187-204. Herring, J.R. and P.S. Liss (1974) A new method for the determination of iodine species in seawater. Deep-Sea Research I. 21: 777-783. Farrenkopf, A.M., G.W. Luther, III, V.W. Truesdale and C.H. van der Weijden (in press) Sub-surface iodide maxima: Evidence for biologically catalyzed redox cycling in Arabian Sea OMZ during the SW intermonsoon. Deep-Sea Research. Takayanagi, K. and G.T.F. Wong (1986) The oxidation of iodide to iodate for the polarographic determination of total iodine in natural waters. Talanta. 33(5): 451-454. Theberge, S.M., III G.W. Luther and A.M. Farrenkopf (in press) On the existence of free and metal complexed sulfide in the Arabian Sea and it's Oxygen Minimum Zone. Deep-Sea Research. Parameters Descriptions Units --------------------------------------------------------------------------- rec record type 1= header record, 3=data record ship NODC ship code cruise originator's cruise id lat latitude reported as decimal degrees North (minus = south) long longitude reported as decimal degrees East (minus = west) date/time date time reported as YYYYMMDDHHmm sta station number from event log cast CTD rosette cast number from event log rec record type always 3 (data record) bot CTD bottle number press sample depth reported as pressure decibars iodide concentration of iodide nM iodine_tot concentration of total iodine nM iodine_tot_sd standard deviation of total iodine --------------------------------------------------------------------------- rec ship cruise lat long date/time sta/cast 1 3250 TTN045 22.4853 61.1836 199503150537 2-001 rec bot press iodide iodine_tot iodine_tot_sd 3 24 1.7 170 411 85 3 22 12.3 182 443 28 3 20 22.2 158 458 90 3 18 32.3 -.9 412 30 3 16 42.4 275 538 98 3 14 52.2 245 574 50 3 12 62.2 180 497 40 3 10 72.4 420 436 9 3 8 102.6 558 567 28 3 6 132.6 455 534 37 3 4 163 365 469 2 3 2 203.3 140 499 4 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 22.4858 61.1711 199503151227 2-003 rec bot press iodide iodine_tot iodine_tot_sd 3 20 303.9 180 494 90 3 18 404.1 475 427 41 3 16 505.4 445 -.9 -.9 3 14 605.7 540 537 23 3 13 605.7 480 505 52 3 12 706.8 32 531 20 3 10 807.9 0 545 32 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 21.1814 63.5463 199503161303 4-003 rec bot press iodide iodine_tot iodine_tot_sd 3 21 253.8 -.9 502 3 3 19 303.9 -.9 529 7 3 17 404.8 -.9 497 23 3 15 505.5 -.9 473 90 3 13 606.6 -.9 505 45 3 11 707.2 134 497 23 3 9 807.7 25 481 69 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 20.5663 64.6637 199503170044 5-002 rec bot press iodide iodine_tot iodine_tot_sd 3 21 251.8 -.9 478 2 3 20 302.7 -.9 473 13 3 19 302.6 -.9 486 3 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 19.8760 65.8841 199503171357 6-003 rec bot press iodide iodine_tot iodine_tot_sd 3 19 305.1 -.9 486 47 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 19.1638 67.1656 199503181352 7-006 rec bot press iodide iodine_tot iodine_tot_sd 3 24 2.9 -.9 405 42 3 23 255.1 -.9 517 83 3 22 305.2 -.9 518 4 3 21 355.8 -.9 520 9 3 20 405.8 -.9 467 34 3 19 455.9 -.9 557 18 3 18 506.2 -.9 537 3 3 17 556.5 -.9 614 70 3 16 606.9 -.9 516 99 3 15 657.5 -.9 553 72 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 18.2834 67.5679 199503200014 8-001 rec bot press iodide iodine_tot iodine_tot_sd 3 21 12.2 154 520 25 3 19 22.1 226 494 12 3 13 52.2 228 -.9 -.9 3 9 72.3 215 483 47 3 7 102.3 213 449 43 3 5 132.4 214 -.9 -.9 3 3 162.7 525 -.9 -.9 3 2 203 734 720 65 3 1 252.3 704 750 18 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 18.2814 67.5683 199503200203 8-003 rec bot press iodide iodine_tot iodine_tot_sd 3 21 254.3 753 -.9 -.9 3 19 304.7 825 835 80 3 17 405.3 662 700 26 3 15 506.6 734 720 35 3 14 607.2 366 750 27 3 11 708.1 256 -.9 -.9 3 9 809 10 -.9 -.9 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 15.3935 68.7302 199503211425 11-005 rec bot press iodide iodine_tot iodine_tot_sd 3 22 141.8 593 -.9 -.9 3 21 141.7 628 -.9 -.9 3 20 304.2 647 -.9 -.9 3 17 404.9 577 -.9 -.9 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 14.9173 66.8821 199503220247 12-001 rec bot press iodide iodine_tot iodine_tot_sd 3 20 43.7 -.9 488 8 3 19 53.8 -.9 435 16 3 17 73.4 -.9 454 12 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 10.8172 64.9988 199503242313 14-001 rec bot press iodide iodine_tot iodine_tot_sd 3 19 22.4 315 -.9 -.9 3 13 52.7 213 -.9 -.9 3 9 72.6 238 -.9 -.9 3 7 102.9 260 -.9 -.9 3 5 132.1 0 -.9 -.9 3 3 163 60 -.9 -.9 3 2 203.1 29 -.9 -.9 3 1 253 0 -.9 -.9 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 10.8153 64.9949 199503250050 14-003 rec bot press iodide iodine_tot iodine_tot_sd 3 19 306 1.7 -.9 -.9 3 17 405.7 1.5 -.9 -.9 3 15 506.8 1.1 -.9 -.9 3 13 607.4 0 -.9 -.9 3 11 708.7 3.8 -.9 -.9 3 9 809.2 0 -.9 -.9 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 12.0691 65.0002 199503250844 15-001 rec bot press iodide iodine_tot iodine_tot_sd 3 19 23.2 321 -.9 -.9 3 9 73.4 170 -.9 -.9 3 3 163.2 500 -.9 -.9 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 14.4618 64.8983 199503270330 17-005 rec bot press iodide iodine_tot iodine_tot_sd 3 21 32.4 282 -.9 -.9 3 19 52.5 272 -.9 -.9 3 17 72.4 211 -.9 -.9 3 14 102.7 316 -.9 -.9 3 11 132.9 303 -.9 -.9 3 9 152.7 730 -.9 -.9 3 7 172.9 743 -.9 -.9 3 5 192.9 712 -.9 -.9 3 4 202.7 730 -.9 -.9 3 3 212.8 785 -.9 -.9 3 2 233.1 630 -.9 -.9 3 1 252.5 686 -.9 -.9 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 14.4302 64.8986 199503271125 17-008 rec bot press iodide iodine_tot iodine_tot_sd 3 22 305 652 -.9 -.9 3 20 405.5 450 -.9 -.9 3 19 455.4 102 -.9 -.9 3 18 506.8 84 -.9 -.9 3 17 555.9 11 -.9 -.9 3 16 606.8 44 -.9 -.9 3 15 657.6 11 -.9 -.9 3 13 806 3.7 -.9 -.9 3 12 907.1 4 -.9 -.9 3 11 1007.2 1.2 -.9 -.9 3 9 1209.8 2.3 -.9 -.9 3 6 1512.5 2.1 -.9 -.9 3 2 1918.2 7.7 -.9 -.9 3 1 2017.7 0 -.9 -.9 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 14.0007 64.8986 199503271535 17-009 rec bot press iodide iodine_tot iodine_tot_sd 3 17 157.4 888 -.9 -.9 3 16 167.7 723 -.9 -.9 3 15 177.6 953 -.9 -.9 3 14 188 522 -.9 -.9 3 13 197.9 745 -.9 -.9 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 14.4302 64.8986 199503272053 17-011 rec bot press iodide iodine_tot iodine_tot_sd 3 9 2271.8 0 -.9 -.9 3 7 2526.5 2 -.9 -.9 3 5 3033.8 8.6 -.9 -.9 3 3 3541.9 0 -.9 -.9 3 1 3846.8 2.6 -.9 -.9 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 16.0020 61.9793 199503301501 21-005 rec bot press iodide iodine_tot iodine_tot_sd 3 11 253.4 772 -.9 -.9 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 16.0003 61.9991 199503301950 21-006 rec bot press iodide iodine_tot iodine_tot_sd 3 19 757.5 24 -.9 -.9 3 17 1009.7 14 -.9 -.9 3 16 1261.7 72 -.9 -.9 3 14 1514.8 19 -.9 -.9 3 2 3853.4 0 -.9 -.9 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 16.0007 61.9989 199503311558 21-013 rec bot press iodide iodine_tot iodine_tot_sd 3 24 2 -.9 -.9 -.9 3 23 42.8 182 -.9 -.9 3 22 73.1 180 -.9 -.9 3 21 93.2 178 -.9 -.9 3 20 203.3 310 -.9 -.9 3 19 223.6 772 -.9 -.9 3 18 243.5 620 -.9 -.9 3 17 264 671 -.9 -.9 3 16 283.9 863 -.9 -.9 3 15 304 796 -.9 -.9 3 14 324.2 772 -.9 -.9 3 13 344.1 881 -.9 -.9 3 12 364.3 501 -.9 -.9 3 11 384.6 673 -.9 -.9 3 10 404.7 248 -.9 -.9 3 9 425 238 -.9 -.9 3 8 445.1 346 -.9 -.9 3 7 465.3 150 -.9 -.9 3 6 485.2 54 -.9 -.9 3 5 505.6 190 -.9 -.9 3 4 525.7 180 -.9 -.9 3 3 555.7 6.2 -.9 -.9 3 2 605.1 90 -.9 -.9 3 1 652.2 17 -.9 -.9 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 16.0195 61.9611 199503311848 21-015 rec bot press iodide iodine_tot iodine_tot_sd 3 12 123.1 132 -.9 -.9 3 11 133.1 190 -.9 -.9 3 10 143.4 430 -.9 -.9 3 9 153.3 281 -.9 -.9 3 8 163.2 500 -.9 -.9 3 7 173.3 159 -.9 -.9 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 17.7269 58.8023 199504050836 27-005 rec bot press iodide iodine_tot iodine_tot_sd 3 5 1211.2 370 -.9 -.9 3 19 303.8 240 -.9 -.9 3 21 253.6 160 -.9 -.9 rec ship cruise lat long date/time sta/cast 1 3250 TTN045 18.0830 58.0077 199504060126 28-005 rec bot press iodide iodine_tot iodine_tot_sd 3 15 504.1 32 -.9 -.9 3 17 403.8 37 -.9 -.9 3 19 303.4 170 -.9 -.9 3 21 253 39 -.9 -.9