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Salinity, Alkalinity, and Calcium of the Weddell Sea

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Salinity, Alkalinity, and Calcium of the Weddell Sea Chen, C-T. 1982. Carbonate chemistry during wEPoLEx-81. Antarctic Gordon, A. E. Molinelli, and I. Baker. 1982. Southern ocean atlas. New Journal of the U.S., 17(5), 102 - 103. York: Columbia University Press. Chen, C-T. 1984. Carbonate chemistry of the Weddell Sea, (DOE! Huber, BA., J. Jennings, C-T. Chen, J. Marra, S. Rennie, P. Mele, and A. EV!10611-4.) Washington, D.C.: U.S. Government Printing Office. Gordon. 1983. Reports of the U.S-U.S.S.R. Weddell Polynya Expedition. Foster, T. D., and J.H. Middleton. 1979. Variability in the bottom water of (Vol. 11-hydrographical data LDGO 83-1.) Palisades, N.Y.: Lamont- the Weddell Sea. Deep-Sea Research, 26A, 743 - 762. Doherty Geological Observatory of Columbia University. Reid, J.L., and R.J. Lynn. 1971. On the influence of Norwegian-Green- GEOSECS Atlantic Expedition. 1981. Sections and profiles, (Vol. 2). (A. E. land and Weddell Seas upon the bottom waters of the Indian and Bainbridge, Project Director, National Science Foundation.) Wash- Pacific Oceans. Deep-Sea Research, 18, 1063 - 1088. ington, D.C.: U.S. Government Printing Office. Reid, J.L., W.D. Nowlin, Jr., and W.C. Patzert. 1977. On the charac- Gordon, A.L. 1978. Deep Antarctic convection west of Maud Rise. teristics and circulation of the southwestern Atlantic Ocean. Journal of Journal of Physical Oceanography, 8, 600 - 612. Physical Oceanography, 7, 62 - 91. Gordon, A.L. 1982. Weddell Deep Water variability. Journal of Marine Schlemmer, F.C. 1978. Structure and spreading of Antarctic Bottom Research, 40 (supplement), 199 - 217. Waters in oceanic basins adjacent to Antarctica. (Doctoral disserta- Gordon, A. and B.A. Huber. 1984. Thermohaline stratification below tion, Texas A&M University, College Station, Texas.) the Southern ocean sea ice. Journal of Geophysical Research, 89, 641 - Weiss, R.F., H.G. Ostlund, and H. Craig. 1979. Geochemical studies of 648. the Weddell Sea. Deep-Sea Research, 26, 1093 - 1120. Salinity, alkalinity, and calcium samples, however, contribute to most of the deviations, thus the results should not be taken at face value without further of the Weddell Sea ice confirmation. The average density salinity is only 0.003 X 10 higher than the average conductivity salinity if we exclude these four samples (14-4, 0-7 centimeters, 14-20 centimeters, 32-38 C-T.A. CHEN centimeters, and 38-46 centimeters). This difference is smaller than the combined precision, 0.005 x 10 1, in the conductivity College of Oceanography and density measurements. Oregon State University Corvallis, Oregon 97331 8000 Sea-ice formation and melting have been known to modify eawater composition (see, for instance, Reeburgh and Spring- r-Young 1983). Jones, Coote, and Levy (1983) demonstrated hat surface seawater had an excess alkalinity (TA) in the Baffin 6000 ay (between Canada and Greenland) during the summer sea- on and attributed the excess to calcium carbonate (CaCO3) rr f om sea-ice meltwater. They also suggested that the excess lkalinity in the summer Weddell Sea reported by Weiss, Os- 4 t und, and Craig (1979) came from the sea-ice meltwater. Z owever, no Weddell Sea ice samples have yet been analyzed 4000 O,p for alkalinity or calcium (Ca). We collected broken chunks of sea ice in the Weddell Sea d.iring the Weddell Polynya Expedition (9 October to 25 November 1981) on Mikhail Somov (Gordon 1982; Chen 1984). In A addition, samples from ice cores collected by S. Ackley on 2000 Somov were melted and shipped to Oregon State University for 0 20 30 analysis. Conductivity salinities and densities of meltwater were measured with an Autosal and a Sodev 02D densimeter, S respectively, using standard seawater P91 for calibration. The Figure 1. Normalized alkalinity (NTA) vs. salinity for melt sea-ice salinities were also calculated from the densities and a seawater samples. Triangles denote the standards. ("0/00" denotes "parts equation of state (Millero and Poisson 1981). per thousand." "ieq/kg" denotes "micro equivalents per Both conductivity salinities and density salinities are listed in kilogram:) the table. On the average, the density salinities are 0.0104 x 10 higher than the conductivity salinities, perhaps reflecting higher proportions of multi-valence ions trapped in the ice (Zubov 1945; Nelson and Thompson 1954; Thompson and Written while on sabbatical leave at the National Sun Yat-Sen Univer- Nelson 1956; Assur 1958; Tsurikov 1965; Richardson 1976). Four sity, Kaohsiung, Taiwan, Republic of China. 1985 REVIEW 117 The alkalinities of meitwaters were also measured using the References method of Culberson, Pytkowicz, and Hawley (1970), and P91 and a weight-diluted P91 as standards. The normalized al- kalinity (NTA TA x 35/salinity) values are all higher than found in the Weddell seawater, especially at low salinities (fig- Assur, A. 1958. Composition of sea ice and its tensile strength. Arctic Sea ure 1 and the table). Qualitatively these results agree with Ice Conference Proceedings, (NAS-NRC Publication on W598), Wash- earlier reports (Wiese 1930; Laktionov 1931; Zubov 1945; Jones ington, D.C.: National Academy of Sciences. and Coote 1981; Jones et al. 1983), but the accuracy is suspect Chen, C-T.A. 1984. Carbonate Chemistry of the Weddell Sea. (DOE because the methodology has not yet been fully developed for technical report DOE/EV/10611-4.) Washington, D.C.: U.S. Govern- alkalinity measurements at low salinities. Our normalized cal- ment Printing Office. cium (NCa = Ca x 35/salinity) values (table and figure 2) are Culberson, C.H., R.M. Pytkowicz, and J.E. Hawley. 1970. Seawater generally higher than the seawater values, as expected alkalinity determination by the pH method. Journal of Marine Research, (Thompson and Nelson 1956) but do not correlate with NTA or 28, 15-20. salinity. These NCa values are also suspect because of insuffi- Gordon, A.L. 1982. The U.S.-U.S.S.R. Weddell Polynya Expedition. cient calibration. We agree with Reeburgh and Springer-Young Antarctic Journal of the U.S., 17(5), 96 - 98. (1983) that this is a fertile area for careful laboratory and field Jones, E.P., and A.R. Coote. 1981. Oceanic CO 2 produced by the pre- studies. cipitation of CaCO3 from brines in sea ice. Journal of Geophysical Re- We acknowledge the assistance provided by S. Ackley, A.L. search, 86, 11041 - 11043. Gordon, and E. Sarukhanyan and the hospitality of the Na- Jones, E. P., A.R. Coote, and E. M. Levy. 1983. Effect of sea ice meltwater tional Sun Yat-Sen University. Financial support was provided on the alkalinity of seawater. Journal of Marine Research, 41, 43 - 52. by the Department of Energy (19X-89608C under Martin Mar- Laktionov, A.F. 1931. The properties of sea ice. Nouchno-Issledovatelskii ietta Energy Systems, Inc., contract DE-ACO5-84 OR 21400) and institut p0 Izucheniiu Severa, Trudy, 49, 71 - 96. (In Russian. Detailed National Science Foundation grant OCE 82-15053. information translated in Zubov 1945.) Conductivity salinity, density salinity, normalized alkalinity, and salinity of Weddell Sea ice. Normalized alkalinity Normalized calci,. (in microequivalents (in micromoles Sample Conductivity Salinity Density Salinity Aa per kilogram) ri per kilogram) 10/24 broken ice 5.769 5.760 9 3,750 0.83 10,122 10/26 broken ice 5.917 5.906 11 3,590 0.83 10,284 10/29 broken ice 8.446 8.455 -9 3,210 0.82 10,276 10/31 broken ice 16.968 16.974 -6 2,760 0.75 10,398 11/3 broken ice 6.180 6.182 -2 3,560 0.83 11/3a broken ice 4.554 4.555 3,740 0.85 10,518 11/8 broken ice 2.795 2.782 13 5,360 0.86 10,310 11 /8a broken ice 1.261 1.257 4 7,490 0.88 10,810 11/8 25-35 centimeter 2.596 2.605 -9 7,100 0.87 10,233 11/8 35-45 centimeter 1.544 1.557 -13 6,650 0.88 10,205 11/8 50-60 centimeter 1.243 1.250 -7 6,730 0.89 10,330 11/13 broken ice 6.194 6.182 12 3,340 0.83 10,132 14-4 0-7 centimeter 4.853 4.897 -44 3,050 0.84 10,540 14-4 7-14 centimeter 4.283 4.306 -23 3,660 0.85 10,209 14-4 14-20 centimeter 3.976 4.032 -66 3,780 0.85 10,218 14-4 20-26 centimeter 2.193 2.202 -9 3,680 0.87 10,290 14-4 26-32 centimeter 3.104 3.114 -10 4,460 0.86 10,330 14-4 32-38 centimeter 4.079 4.115 -36 14-4 38-46 centimeter 3.940 3.975 -35 4,020 0.85 10,294 14-4 46-52 centimeter 5.264 5.278 -14 3,150 0.84 10,440 14-4 52-58 centimeter 4.492 4.498 -6 3,280 0.85 10,316 14-4 58-64 centimeter 4.531 4.524 7 3,710 0.85 10,493 14-4 64-70 centimeter 5.328 5.334 6 4,180 0.84 10,313 a A = 1000 (conductivity salinity/density salinity) b f = my best estimate for the hydrogen activity, needed for alkalinity measurements 118 ANTARCTIC JOURNAL Millero, F.J., and A. Poisson. 1981. International one-atmosphere equa- tion of state of seawater. Deep-Sea Research, 28A, 625 - 629. 10800 - Nelson, K.H., and T.G. Thompson. 1954. Deposition of salts from sea water by frigid concentration. (University of Washington Department of Oceanography, Technical Report No. 29.) Seattle: University of Washington Press.
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