Paleoproductivity and its environmental constraints in the Scotia Sea, Antarctica since 34 ka BP
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摘要: 本文通过对南极斯科舍海东南部DC-11岩芯生物硅、有机氮、TFe2O3与有机氮同位素的年代学分析,重建了该海区3.4万年以来古生产力与环境演变历史。研究结果表明,生物硅、有机氮含量与南极温度变化基本一致,暖期高、冷期低;有机氮同位素值与南大洋海冰变化相吻合,暖期小、冷期大,冷期硝酸盐利用率大于暖期。从末次冰期、末次冰消期至全新世,研究区古生产力与环境变化显著,南极冷倒转等千年尺度的变化明显;海冰在气候、营养盐与古生产力之间起着重要的关联作用。冰期或冷期海冰的加强导致表层水层化加强,深层水及其营养盐的上涌减弱,表层海洋硝酸盐等相对匮乏,生产力降低。研究区现代与全新世铁供应充足,在风尘盛行的末次冰期和冰消期呈过剩状态,明显不同于亚南极。Abstract: Paleoproductivity and environmental evolution since 34 ka BP in the southeastern Scotia Sea, Antarctica were reconstructed by the chronological analyses of biogenic opal (BSiO2), organic nitrogen (Norg), TFe2O3 and organic nitrogen isotopes (δ15Norg) in Core DC-11. Changes in BSiO2 and Norg contents are basically consistent with the Antarctic temperature, being higher in warm times. δ15Norg is coincident with the Antarctic sea ice, being greater and reflecting enhanced nitrate utilization in surface water during cold periods. From Last Glacial, Last Deglaciation to Holocene, paleoproductivity and environment changed significantly, and the millennial variability such as the Antarctic Cold Reversal (ACR) is prominent in the study area. Sea ice plays an important role in correlations between the climate, nutrients and paleoproductivity. The increase of sea ice during the glacial or cold periods caused stronger stratification of surface waters, weaker upwelling of deep waters and their dissolved nutrients to the surface ocean, and then resulted in enhanced nitrate utilization and lower paleoproductivity in surface water. Iron supply in the study area is sufficient in present-day and Holocene while it is excessive during Last Glacial and Last Deglaciation due to more developed dust, which is obviously different from that in the Subantarctic Zone.
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Key words:
- Antarctica /
- the Scotia Sea /
- paleoproductivity /
- nutrients /
- sea ice /
- stratification of surface waters
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图 1 斯科舍海取样站位与环流分布(据文献[18-20]修改)
SHW(灰色箭头):南半球西风带;APF(蓝色虚线):南极极锋;ACC(灰色箭头):南极绕极流;SBACC(灰色虚线):南极绕极流南边界;WG(白色首尾相接的箭头):威德尔涡流;WSBW(红色箭头):威德尔海底层水;WSDW(桔色箭头):威德尔海深层水;WSI(白色细虚线)和SSI(白色粗虚线):南半球冬季和夏季海冰线;IA(空心箭头):冰山通道。浅白色虚线为图2所示的营养盐剖面位置
Fig. 1 Map of the Scotia Sea showing Core DC-11 and marine circulation (modified from references [18-20])
SHW (gray arrow): the dominant direction of the Southern Hemisphere Westerlies; APF (dotted blue line): the Antarctic Polar Front; ACC (yellow arrow): the Antarctic Circumpolar Current; SBACC(gray dotted line): the Southern Boundary of the Antarctic Circumpolar Current; WSBW (red arrow): the Weddell Sea Bottom Water; WSDW (brown arrow): the Weddell Sea Deep Water; WG (white arrows end to end): the Weddell Gyre; WSI (white fine dotted line) and SSI (white coarse dotted line): the austral winter and summer sea ice limits, respectively; IA (hollow arrow): the Iceberg Alley. Light white dotted line is the section of nutrients shown in Fig.2
图 2 37°W附近断面现代硅酸盐(a)与硝酸盐(b)含量分布(据文献[27]修改)
LCDW:绕极深层水下层;UCDW:绕极深层水上层;SAMW:亚南极模态水;AAIW:南极中层水;AABW:南极底层水
Fig. 2 Dissolved silica (a) and nitrate concentrations (b) near longitude 37°W (modified from reference [27])
LCDW: Lower Circumpolar Deep Water;UCDW: Upper Circumpolar Deep Water; SAMW: Subantarctica Mode Water; AAIW: Antarctica Intermediate Water; AABW: Antarctica Bottom Water
表 1 DC-11岩芯AMS14C测年结果与年龄控制点
Tab. 1 AMS14C data and adopted age controls of Core DC-11
深度/cm 测试材料 14C年龄/cal a BP 校正后日历年龄/cal a BP 有效年龄控制点/cal a BP 0 − − − 0 1~2 有机碳 2 840±30 1 486±142 150(1.5 cm) 20~21 有机碳 4 040±30 2 924±157 2 056(20.5 cm) 46~47 有机碳 5 260±30 4 522±177 4 663(46.5 cm) 132~134 有机碳 12 660±40 13 239±131 13 339(133 cm) 194~196 有机碳 20 910±70 23 629±285 19 622*(195 cm) 224~226 有机碳 25 400±100 28 141±312 25 722*(222 cm) 254~256 有机碳 30 810±160 33 698±320 33 698(255 cm) 注:*表示通过DC-11岩芯磁化率曲线与EDML冰芯曲线对比得到的年龄(图3)。 -
[1] Fischer H, Schmitt J, Lüthi D, et al. The role of Southern Ocean processes in orbital and millennial CO2 variations—a synthesis[J]. Quaternary Science Reviews, 2010, 29(1/2): 193−205. [2] Gottschalk J, Skinner L C, Jaccard S L, et al. Southern Ocean link between changes in atmospheric CO2 levels and northern-hemisphere climate anomalies during the last two glacial periods[J]. Quaternary Science Reviews, 2020, 230: 106067. doi: 10.1016/j.quascirev.2019.106067 [3] Kumar N, Anderson R F, Mortlock R A, et al. Increased biological productivity and export production in the glacial Southern Ocean[J]. Nature, 1995, 378(6558): 675−680. doi: 10.1038/378675a0 [4] Frank M, Gersonde R, Van Der Loeff M R, et al. Similar glacial and interglacial export bioproductivity in the Atlantic Sector of the Southern Ocean: multiproxy evidence and implications for glacial atmospheric CO2[J]. Paleoceanography, 2000, 15(6): 642−658. doi: 10.1029/2000PA000497 [5] Chase Z, Anderson R F, Fleisher M Q, et al. Accumulation of biogenic and lithogenic material in the Pacific sector of the Southern Ocean during the past 40, 000 years[J]. Deep-Sea Research, Part II: Topical Studies in Oceanography, 2003, 50(3/4): 799−832. [6] Jaccard S L, Hayes C T, Martínez-García A, et al. Two modes of change in Southern Ocean productivity over the past million years[J]. Science, 2013, 339(6126): 1419−1423. doi: 10.1126/science.1227545 [7] Diekmann B. Sedimentary patterns in the late Quaternary Southern Ocean[J]. Deep-Sea Research Part II: Topical Studies in Oceanography, 2007, 54(21/22): 2350−2366. [8] Diekmann B, Kuhn G. Provenance and dispersal of glacial-marine surface sediments in the Weddell Sea and adjoining areas, Antarctica: Ice-rafting versus current transport[J]. Marine Geology, 1999, 158(1/4): 209−231. [9] Krueger S, Leuschner D C, Ehrmann W, et al. Ocean circulation patterns and dust supply into the South Atlantic during the last glacial cycle revealed by statistical analysis of kaolinite/chlorite ratios[J]. Marine Geology, 2008, 253(3/4): 82−91. [10] Latimer J C, Filippelli G M. Terrigenous input and paleoproductivity in the Southern Ocean[J]. Paleoceanography, 2001, 16(6): 627−643. doi: 10.1029/2000PA000586 [11] Latimer J C, Filippelli G M. Sedimentary iron records from the Cape Basin[J]. Deep-Sea Research Part II: Topical Studies in Oceanography, 2007, 54(21/22): 2422−2431. [12] Noble T L, Piotrowski A M, Robinson L F, et al. Greater supply of Patagonian-sourced detritus and transport by the ACC to the Atlantic sector of the Southern Ocean during the last glacial period[J]. Earth and Planetary Science Letters, 2012, 317−318: 374−385. doi: 10.1016/j.jpgl.2011.10.007 [13] Holm-Hansen O, Naganobu M, Kawaguchi S, et al. Factors influencing the distribution, biomass, and productivity of phytoplankton in the Scotia Sea and adjoining waters[J]. Deep-Sea Research II: Topical Studies in Oceanography, 2004, 51(12/13): 1333−1350. [14] Korb R E, Whitehouse M J, Ward P, et al. Regional and seasonal differences in microplankton biomass, productivity, and structure across the Scotia Sea: implications for the export of biogenic carbon[J]. Deep-Sea Research II: Topical Studies in Oceanography, 2012, 59−60: 67−77. doi: 10.1016/j.dsr2.2011.06.006 [15] Maldonado A, Bohoyo F, Galindo-Zaldívar J, et al. Ocean basins near the Scotia–Antarctic plate boundary: Influence of tectonics and paleoceanography on the Cenozoic deposits[J]. Marine Geophysical Researches, 2006, 27(2): 83−107. doi: 10.1007/s11001-006-9003-4 [16] Eagles G, Livermore R A, Fairhead J D, et al. Tectonic evolution of the west Scotia Sea[J]. Journal of Geophysical Research: Solid Earth, 2005, 110(B2): B02401. [17] Stuart K M, Long D G. Tracking large tabular icebergs using the SeaWinds Ku-band microwave scatterometer[J]. Deep-Sea Research Part II: Topical Studies in Oceanography, 2011, 58(11/12): 1285−1300. [18] Weber M E, Clark P U, Kuhn G, et al. Millennial-scale variability in Antarctic ice-sheet discharge during the last deglaciation[J]. Nature, 2014, 510(7503): 134−138. doi: 10.1038/nature13397 [19] Orsi A H, Johnson G C, Bullister J L. Circulation, mixing, and production of Antarctic Bottom Water[J]. Progress in Oceanography, 1999, 43(1): 55−109. doi: 10.1016/S0079-6611(99)00004-X [20] Palmer M, Gomis D, Flexas M D M, et al. Water mass pathways and transports over the South Scotia Ridge west of 50°W[J]. Deep-Sea Research Part I: Oceanographic Research Papers, 2012, 59: 8−24. doi: 10.1016/j.dsr.2011.10.005 [21] García M, Lobo F J, Maldonado A, et al. High-resolution seismic stratigraphy and morphology of the Scan Basin contourite fan, southern Scotia Sea, Antarctica[J]. Marine Geology, 2016, 378: 361−373. doi: 10.1016/j.margeo.2016.01.011 [22] Whitehouse M J, Atkinson A, Korb R E, et al. Substantial primary production in the land-remote region of the central and northern Scotia Sea[J]. Deep-Sea Research Part II: Topical Studies in Oceanography, 2012, 59−60: 47−56. doi: 10.1016/j.dsr2.2011.05.010 [23] Nielsdóttir M C, Bibby T S, Moore C M, et al. Seasonal and spatial dynamics of iron availability in the Scotia Sea[J]. Marine Chemistry, 2012, 130−131: 62−72. doi: 10.1016/j.marchem.2011.12.004 [24] Park J, Park T, Yang E J, et al. Early summer iron limitation of phytoplankton photosynthesis in the Scotia Sea as inferred from fast repetition rate fluorometry[J]. Journal of Geophysical Research: Oceans, 2013, 118(8): 3795−3806. doi: 10.1002/jgrc.20281 [25] de Jong J, Schoemann V, Lannuzel D, et al. Natural iron fertilization of the Atlantic sector of the Southern Ocean by continental shelf sources of the Antarctic Peninsula[J]. Journal of Geophysical Research: Biogeosciences, 2012, 117(G1): G01029. [26] Ellwood M J, Wille M, Maher W. Glacial silicic acid concentrations in the Southern Ocean[J]. Science, 2010, 330(6007): 1088−1091. doi: 10.1126/science.1194614 [27] Sarmiento J L, Simeon J, Gnanadesikan A, et al. Deep ocean biogeochemistry of silicic acid and nitrate[J]. Global Biogeochemical Cycles, 2007, 21(1): GB1S90. [28] Anderson R F, Ali S, Bradtmiller L I, et al. Wind-driven upwelling in the Southern Ocean and the deglacial rise in atmospheric CO2[J]. Science, 2009, 323(5920): 1443−1448. doi: 10.1126/science.1167441 [29] Fogwill C J, Turney C S M, Golledge N R, et al. Antarctic ice sheet discharge driven by atmosphere-ocean feedbacks at the Last Glacial Termination[J]. Scientific Reports, 2017, 7: 39979. doi: 10.1038/srep39979 [30] 张富元, 李安春, 林振宏, 等. 深海沉积物分类与命名[J]. 海洋与湖沼, 2006, 37(6): 517−523. doi: 10.3321/j.issn:0029-814X.2006.06.007Zhang Fuyuan, Li Anchun, Lin Zhenhong, et al. Classification and nomenclature of deep sea sediments[J]. Oceanologia et Limnologia Sinica, 2006, 37(6): 517−523. doi: 10.3321/j.issn:0029-814X.2006.06.007 [31] Fischer H, Fundel F, Ruth U, et al. Reconstruction of millennial changes in dust emission, transport and regional sea ice coverage using the deep EPICA ice cores from the Atlantic and Indian Ocean sector of Antarctica[J]. Earth and Planetary Science Letters, 2007, 260(1/2): 340−354. [32] Müller P J, Schneider R. An automated leaching method for the determination of opal in sediments and particulate matter[J]. Deep-Sea Research Part I: Oceanographic Research Papers, 1993, 40(3): 425−444. doi: 10.1016/0967-0637(93)90140-X [33] Xiao Wenshen, Frederichs T, Gersonde R, et al. Constraining the dating of late Quaternary marine sediment records from the Scotia Sea (Southern Ocean)[J]. Quaternary Geochronology, 2016, 36: 97−118. [34] Pugh R S, McCave I N, Hillenbrand C D, et al. Circum-Antarctic age modelling of Quaternary marine cores under the Antarctic Circumpolar Current: ice-core dust-magnetic correlation[J]. Earth and Planetary Science Letters, 2009, 284(1/2): 113−123. [35] Weber M E, Kuhn G, Sprenk D, et al. Dust transport from Patagonia to Antarctica–A new stratigraphic approach from the Scotia Sea and its implications for the last glacial cycle[J]. Quaternary Science Reviews, 2012, 36: 177−188. doi: 10.1016/j.quascirev.2012.01.016 [36] Kim S, Yoo K C, Lee II J, et al. Relationship between magnetic susceptibility and sediment grain size since the last glacial period in the Southern Ocean off the northern Antarctic Peninsula-linkages between the cryosphere and atmospheric circulation[J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2018, 505: 359−370. doi: 10.1016/j.palaeo.2018.06.016 [37] Lee II J, Bak Y S, Yoo K C, et al. Climate changes in the South Orkney Plateau during the last 8 600 years[J]. The Holocene, 2010, 20(3): 395−404. doi: 10.1177/0959683609353430 [38] Charles C D, Froelich P N, Zibello M A, et al. Biogenic opal in Southern Ocean sediments over the last 450, 000 years: implications for surface water chemistry and circulation[J]. Paleoceanography, 1991, 6(6): 697−728. doi: 10.1029/91PA02477 [39] Schulz H D, Zabel M. Marine Geochemistry[M]. 2nd ed. Berlin: Springer, 2006: 125−168. [40] Saino T, Hattori A. Geographical variation of the water column distrubution of suspended particulate organic nitrogen and its 15N natural abundance in the Pacific and its marginal seas[J]. Deep-Sea Research Part A: Oceanographic Research Papers, 1987, 34(5/6): 807−827. [41] Galbraith E D, Kienast M, Pedersen T F, et al. Glacial-interglacial modulation of the marine nitrogen cycle by high-latitude O2 supply to the global thermocline[J]. Paleoceanography, 2004, 19(4): PA4007. [42] Francois R, Altabet M A, Burckle L H. Glacial to interglacial changes in surface nitrate utilization in the Indian sector of the Southern Ocean as recorded by sediment δ15N[J]. Paleoceanography, 1992, 7(5): 589−606. doi: 10.1029/92PA01573 [43] Altabet M A, Francois R. Sedimentary nitrogen isotopic ratio as a recorder for surface ocean nitrate utilization[J]. Global Biogeochemical Cycles, 1994, 8(1): 103−116. doi: 10.1029/93GB03396 [44] Robinson R S, Kienast M, Albuquerque A L, et al. A review of nitrogen isotopic alteration in marine sediments[J]. Paleoceanography, 2012, 27(4): PA4203. [45] Crosta X, Shemesh A. Reconciling down core anticorrelation of diatom carbon and nitrogen isotopic ratios from the Southern Ocean[J]. Paleoceanography, 2002, 17(1): 10-1−10-8. [46] François R, Altabet M A, Yu E F, et al. Contribution of Southern Ocean surface-water stratification to low atmospheric CO2 concentrations during the last glacial period[J]. Nature, 1997, 389(6654): 929−935. doi: 10.1038/40073 [47] Sigman D M, Altabet M A, McCorkle D C, et al. The δ15N of nitrate in the Southern Ocean: nitrogen cycling and circulation in the ocean interior[J]. Journal of Geophysical Research: Oceans, 2000, 105(C8): 19599−19614. doi: 10.1029/2000JC000265 [48] Sigman D M, Altabet M A, McCorkle D C, et al. The δ15N of nitrate in the Southern Ocean: consumption of nitrate in surface waters[J]. Global Biogeochemical Cycles, 1999, 13(4): 1149−1166. doi: 10.1029/1999GB900038 [49] Studer A S, Sigman D M, Martínez-García A, et al. Antarctic zone nutrient conditions during the last two glacial cycles[J]. Paleoceanography, 2015, 30(7): 845−862. doi: 10.1002/2014PA002745 [50] WAIS Divide Project Members. Precise interpolar phasing of abrupt climate change during the last ice age[J]. Nature, 2015, 520(7549): 661−665. doi: 10.1038/nature14401 [51] WAIS Divide Project Members. Onset of deglacial warming in West Antarctica driven by local orbital forcing[J]. Nature, 2013, 500(7463): 440−444. doi: 10.1038/nature12376 [52] Wolff E W, Fischer H, Fundel F, et al. Southern Ocean sea-ice extent, productivity and iron flux over the past eight glacial cycles[J]. Nature, 2006, 440(7083): 491−496. doi: 10.1038/nature04614 [53] Xiao Wenshen, Esper O, Gersonde R. Last Glacial-Holocene climate variability in the Atlantic sector of the Southern Ocean[J]. Quaternary Science Reviews, 2016, 135: 115−137. doi: 10.1016/j.quascirev.2016.01.023 [54] Collins L G, Pike J, Allen C S, et al. High-resolution reconstruction of southwest Atlantic sea-ice and its role in the carbon cycle during marine isotope stages 3 and 2[J]. Paleoceanography, 2012, 27(3): PA3217. [55] Andersen K K, Azuma N, Barnola J M, et al. High-resolution record of Northern Hemisphere climate extending into the last interglacial period[J]. Nature, 2004, 431(7005): 147−151. doi: 10.1038/nature02805 [56] Rahmstorf S. Ocean circulation and climate during the past 120, 000 years[J]. Nature, 2002, 419(6903): 207−214. doi: 10.1038/nature01090 [57] Stocker T F. Global change: South dials north[J]. Nature, 2003, 424(6948): 496−499. doi: 10.1038/424496a [58] Barker S, Diz P, Vautravers M, et al. Interhemispheric Atlantic seesaw response during the last deglaciation[J]. Nature, 2009, 457(7233): 1097−1102. doi: 10.1038/nature07770 [59] McManus J F, Francois R, Gherardi J M, et al. Collapse and rapid resumption of Atlantic meridional circulation linked to deglacial climate changes[J]. Nature, 2004, 428(6985): 834−837. doi: 10.1038/nature02494 [60] Gherardi J M, Labeyrie L, Nave S, et al. Glacial-interglacial circulation changes inferred from 231Pa/230Th sedimentary record in the North Atlantic region[J]. Paleoceanography, 2009, 24(2): PA2204. [61] Van Bennekom A J, Berger G W, Van der Gaast S J, et al. Primary productivity and the silica cycle in the Southern Ocean (Atlantic sector)[J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 1988, 67(1/2): 19−30. [62] Neori A, Holm-Hansen O. Effect of temperature on rate of photosynthesis in Antarctic phytoplankton[J]. Polar Biology, 1982, 1(1): 33−38. doi: 10.1007/BF00568752