Seawater [CO32-] and T Effects on Cultured Foraminifera U, Mg, and Sr --------------------------------------------------------------------- NOAA Paleoclimatology Program and World Data Center for Paleoclimatology, Boulder --------------------------------------------------------------------- NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!! NAME OF DATA SET: Seawater [CO32-] and T Effects on Cultured Foraminifera U, Mg, and Sr LAST UPDATE: 1/2005 (Original Receipt by WDC Paleo) CONTRIBUTOR: Ann D. Russell, University of California, Davis IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2005-004 SUGGESTED DATA CITATION: Russell, A.D., et al.. 2005. Seawater [CO32-] and T Effects on Cultured Foraminifera U, Mg, and Sr. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series #2005-004. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCE: Russell, A.D., B. Hoenisch, H.J. Spero, and D.W. Lea. 2004. Effects of seawater carbonate ion concentration and temperature on shell U, Mg, and Sr in cultured planktonic foraminifera. Geochimica et Cosmochimica Acta 68(21), 4347-4361. ABSTRACT: We investigate the sensitivity of U/Ca, Mg/Ca, and Sr/Ca to changes in seawater [CO32-] and temperature in calcite produced by the two planktonic foraminifera species, Orbulina universa and Globigerina bulloides, in laboratory culture experiments. Our results demonstrate that at constant temperature, U/Ca in O. universa decreases by 25 ± 7% per 100 mmol [CO32-] kg-1, as seawater [CO32-] increases from 110 to 470 mmol kg-1. Results from G. bulloides suggest a similar relationship, but U/Ca is consistently offset by ~+40% at the same environmental [CO32-]. In O. universa, U/Ca is insensitive to temperature between 15°C and 25°C. Applying the O. universa relationship to three U/Ca records from a related species, Globigerinoides sacculifer, we estimate that Caribbean and tropical Atlantic [CO32-] was 110 ± 70 mmol kg-1 and 80 ± 40 mmol kg-1 higher, respectively, during the last glacial period relative to the Holocene. This result is consistent with estimates of the glacial–interglacial change in surface water [CO32-] based on both modeling and on boron isotope pH estimates. In settings where the addition of U by diagenetic processes is not a factor, down-core records of foraminiferal U/Ca have potential to provide information about changes in the ocean’s carbonate concentration. Below ambient pH (pH < 8.2), Mg/Ca decreased by 7 ± 5% (O. universa) to 16 ± 6% (G. bulloides) per 0.1 unit increase in pH. Above ambient pH, the change in Mg/Ca was not significant for either species. This result suggests that Mg/Ca-based paleotemperature estimates for the Quaternary, during which surface-ocean pH has been at or above modern levels, have not been biased by variations in surface-water pH. Sr/Ca increased linearly by 1.6 ± 0.4% per 0.1 unit increase in pH. Shell Mg/Ca increased exponentially with temperature in O. universa, where Mg/Ca = 0.85 exp(0.096*T), whereas the change in Sr/Ca with temperature was within the reproducibility of replicate measurements. PERIOD OF RECORD: Modern FUNDING SOURCE: This research was supported by NSF grant OCE9907044 to Ann Russell. DESCRIPTION: This dataset contains geochemical information from laboratory culture experiments conducted to determine the relationships between the U/Ca, Mg/Ca, and Sr/Ca composition of foraminiferal calcite and the temperature and carbonate ion composition of seawater. DATA: Table 1. Experimental conditions for foraminiferal culturing experiments. Mean [CO32-] and DIC concentrations were calculated from mean alkalinity and pH measurements using the program of Lewis and Wallace (1998), with the CO2 constants of Mehrbach (1973), refit by Dickson and Millero (1987), and KSO4 from Dickson (1990) (HPO4- = 0.5 mmol kg-1 and Si = 10 mmol kg-1). Asterisks in the DIC column indicate measured values. Oc and Oa are saturation indices for calcite and aragonite, respectively. Mean Light Alkalinity [CO32-] DIC Experiment Group mE m-2s-1 T°C S m equiv/kg pH mmol/kg mmol/kg Oc, Oa I AR1 299-332 22 33.9 2273±15 8.241±0.023 213 1971-1972 5.2, 3.4 I AR3 299-398 22 33.8 2400±5 8.413±0.019 301 1955-1992 7.3, 4.8 I AR4 299-398 22 33.6 2546±6 8.559±0.006 399 1988 9.7, 6.3 I AR5 299-332 22 33.6 2671±23 8.657±0.012 480 1990-2021 11.6, 7.8 II BH1 23 22 33.6 2253±10 8.165±0.016 182 2000* 4.4, 2.9 II BH2 365 22 33.8 2268±5 8.199±0.019 196 1993* 4.8, 3.1 II BH3 332-349 22 33.7 2047±15 7.742±0.028 76 1965* 1.7, 1.1 II BH4 299 22 33.7 2632±12 8.648±0.015 468 1979* 11.3, 7.4 II BH5 332-365 22 33.7 2436±21 8.425±0.011 311 1997* 7.5, 4.9 II BH6 299 22 33.7 2122±6 7.933±0.006 111 1979* 2.7, 1.7 III AR6 332-365 15 33.8 2268±12 8.222±0.012 171 2016-2031 4.1, 2.6 III AR27 332-365 18 33.7 2260±8 8.169±0.033 166 2001-2037 4.0, 2.6 III AR10 282-332 25 34.2 2269±15 8.208±0.007 216 1936-1973 5.3, 3.5 III AR12 282-332 25 33.7 2265±6 8.214±0.007 216 1949-1954 5.3,3.5 Table 2. Summary of mean (±1 standard error) Me/Ca in cultured foraminifera. N refers to the number of samples included in the mean and standard error. [CO32-]-corrected [CO32-] Mg/Ca Sr/Ca U/Ca U/Ca Experiment Species T°C mmol/kg mmol/mol N mmol/mol N nmol/mol N nmol/mol BH3 O. univ 22 76 9.41±0.90 3 1.26±0.05 3 15.2±2.8 3 - BH6 O. univ 22 111 7.92±1.49 3 1.24±0.06 3 10.9±0.9 3 - AR1, BH2 O. univ 22 205 6.82±0.27 9 1.27±0.01 10 9.3±0.8 10 - AR3, BH5 O. univ 22 306 6.68±0.33 11 1.31±0.01 11 7.3±0.6 11 - AR4 O. univ 22 399 6.42±0.46 6 1.37±0.02 6 6.7±0.5 6 - AR5, BH4 O. univ 22 474 6.49±0.34 10 1.40±0.01 9 4.9±0.4 9 - AR6 O. univ 15 171 3.53±0.11 4 1.24±0.01 3 9.3±0.4 3 8.8±0.4 AR27 O. univ 18 166 5.02±0.33 7 1.28±0.03 6 8.2±0.4 6 7.7±0.4 AR9-12 O. univ 25 216 9.60±0.39 10 1.32±0.02 6 9.4±1.0 7 9.6±1.0 BH1 G. bull 22 182 4.231 1 1.297 1 16.8 1 - BH2 G. bull 22 196 3.821 1 1.326 1 15.3 1 - BH3 G. bull 22 76 7.746 1 1.296 1 - 1 - BH4 G. bull 22 468 2.691 1 1.317 1 8.1 1 - Table 3. Mean (±1sigma) concentrations of uranium and calcium in ambient seawater and culture solutions prepared from filtered seawater using unleached 0.80-micron filters and glass filter apparatus (Experiment I and II) and acid-leached polycarbonate 0.40-micron filters and Nalgene filter apparatus (Experiment III), compared with predicted values (based on salinity) and 1990 measurements. [Ca] [U] U/Ca Sample N (mol/kg) (nmol/kg) (nmol/mol) Ambient# 6 0.0102±0.0001 13.59±0.07 1330±10 Culture# 17 0.0102±0.0001 13.60±0.10 1329±4 Culture* 17 0.0102±0.0001 13.56±0.09 1329±7 Ambient 1990# (0.80 micron filter) 0.0103±0.0002 13.83±0.08 1338±16 Predicted, based on S=33.7 0.0099 13.35 1349 # 0.80-micron filter * 0.40-micron filter Table 4. Summary of Me/Ca relationships with [CO32-] (a) and pH (b) from this study. All regressions and statistics are based on individual sample analyses (not means as plotted in figures). Standard errors of estimate for linearized exponential relationships have units of ln Me/Ca; units for U/Ca are nmol mol-1 and units for Mg/Ca and Sr/Ca are mmol mol-1. Only relationships that are statistically significant (P<0.05) are included, resulting in the exclusion of Mg/Ca vs [CO32-] or pH at [CO32-] > 200 mmol kg-1. Standard Error of Estimate a. Me/Ca Relationship with [CO32-] R2 P Me/Ca [CO32-] mmol kg-1 G. bulloides Mg/Ca = 91.0[CO32-]^(-0.583) 0.31 ln U/Ca = 3.239(±0.057)-0.0024(±0.0002)[CO32-]) 0.99 0.048 0.042 ±18 O. universa U/Ca = 14.2(±1.0)-0.0204(±0.003)[CO32-] 0.42 <0.001 ±2.3 nmol mol-1 ±83 U/Ca = 188(±73.7)*[CO32-]^(-0.58±0.07) 0.54 <0.001 U/Ca = 15.7(±1.65)*exp(-0.0025(±0.0004)[CO32-] 0.47 <0.001 0.257 ±103 Mg/Ca = 10.8(±1.20)-0.019±0.007)[CO32-] ([CO32-] ? 200 mmol kg-1 ) 0.36 0.014 ±1.38 ±73 Mg/Ca = 21.4(±5.77)[CO32-]^(-0.202±0.049) 0.31 ln Mg/Ca = 2.100(±0.072)-0.0006(±0.0002)[CO32-] 0.14 0.008 0.172 ±117 Sr/Ca = 1.19(±0.012)+0.00044(±4x10-5)[CO32-] 0.79 10e-15 ±0.028 mmol mol-1 ±61 b. Me/Ca Relationship with pH R2 P Me/Ca pH G. bulloides Mg/Ca = 2.35x109pH^(-9.573) 0.98 ln Mg/Ca = 10.99(±1.345)-1.165(±0.164)pH 0.96 0.02 0.105 ±0.09 ln U/Ca = 14.80(±0.675)-1.470(±0.081)pH 0.99 0.03 0.031 ±0.02 O. universa Mg/Ca = 55.9(±15.2)-5.97(±1.88)pH ([CO32-] <= 200 mmol kg-1 ) 0.41 0.008 ±1.33 ±0.22 Mg/Ca = 13.6(±8.11)-0.829(±0.959)pH ([CO32-] >= 200 mmol kg-1 ) -0.01 0.393 ±0.923 ±1.11 Mg/Ca = 3464[CO32-]^(-2.934) 0.31 ln Mg/Ca = 4.864(±0.865)-0.352(±0.103)pH 0.21 0.002 0.165 ±0.23 ln U/Ca = 12.3(±1.4)-1.2(±0.16)pH 0.59 10e-9 0.25 ±0.16 U/Ca = 98.5(±11.0)-10.8(±1.32)pH 0.63 10e-10 ±2.1 nmol mol-1 ±0.15 Sr/Ca = -0.364(±0.186)+0.201(±0.022)pH 0.67 10e-11 ±0.035 mmol mol-1 ±0.15 Table 5. Summary of Me/Ca relationships with temperature from this study. Units for standard errors are the same as for Table 4. Relationships for Mg/Cacorr and Sr/Cacorr versus temperature were corrected for the effects of varying [CO32-] using relationships in Figure 1. Only relationships that are statistically significant (P<0.05) are included, resulting in the exclusion of Sr/Cacorr versus temperature. Standard Error of Estimate Me/Ca Relationship with Temperature R2 P Me/Ca Temperature °C O. universa ln Mg/Ca = -0.162(±0.144)+0.096(±0.007)T 0.88 1.00E-13 0.13 ±1.4 ln Mg/Cacorr = -0.349(±0.145)+0.104(±0.007)T 0.89 1.00E-14 0.131 ±1.3 Sr/Ca = 1.16(±0.03)+0.0056(±0.0015)T 0.32 0.007 ±0.03 mmol mol-1 ±3.0 Table 6. Average (± 1 standard deviation) Holocene U/Ca in G. sacculifer and [CO32-] estimated from U/Ca in Atlantic and Caribbean cores, compared to [CO32-] calculated from WOCE measurements (a); and average (± 1 standard deviation) glacial U/Ca and [CO32-] and glacial-interglacial D[CO32-] (b). Errors in G-IG D[CO32-] are propagated from the variance of Holocene and glacial U/Ca. (a) Holocene WOCE Estimated U/Ca [CO32-] [CO32-] Core Interval kyr N nmol mol-1 mmol kg-1 mmol kg-1 CP6001-4 0.3-11 18 7.9±0.2 280±50 290 EN066-17GGC 0-7 9 9.3±0.2 210±20 275 EN066-39GGC 0-11 5 7.9±0.4 280±40 275 (b) Glacial Estimated Estimated U/Ca [CO32-] G-IG D[CO32-] Core Interval kyr N nmol mol-1 mmol kg-1 mmol kg-1 CP6001-4 14-22 16 6.0±0.2 390±50 110±70 EN066-17GGC 13-23 11 7.7±0.2 290±30 80±40 EN066-39GGC 14-25 5 6.3±0.1 360±10 80±40 Table A1. Sample Me/Ca ratios, experimental conditions, and mean (± 1 standard error) length, weight, and wall thickness of cultured O. universa. Values marked with * were not included in means. Dissolved Mean Mean Wall Sample [CO32-] Calcite Length Weight Thickness Mg/Ca Sr/Ca U/Ca Name T°C mmol kg-1 Weightmmg micron mmg micron N mmol/mol mmol/mol nmol/mol AR1-A 22 213 19 493±11 18±1 10 5 5.821 1.274 17.2* AR1-B 22 213 61 493±17 23±1 13 5 6.124 1.249 7 AR1-C 22 213 58 522±16 27±1 14 6 8.233 1.307 14.6 AR1-D 22 213 117 564±14 34±1 15 9 7.932 1.274 9.1 AR1-E 22 213 58 640±42 38±1 13 4 6.979 1.231 9.9 AR1-3 22 213 61 600±13 53±5 20 2 6.538 1.311 11.4 AR1-5 22 213 62 667±90 73±15 23 2+ 7.028 1.25 9.6 AR3-A 22 301 14 427±8 15±2 11 3 5.259 1.294 11.8* AR3-B 22 301 32 467±26 25±1 16 2 5.396 1.301 8.3 AR3-C 22 301 30 520±16 29±1 15 3 5.656 1.311 9.2 AR3-D 22 301 124 568±18 33±1 14 8 7.265 1.306 7.9 AR3-E 22 301 180 575±8 38±1 16 10 6.844 1.325 6.3 AR3-F 22 301 231 573±12 43±1 18 6 5.946 1.306 6.3 AR3-H 22 301 88 653±40 59±1 19 2 8.082 1.331 10.9 AR3-I 22 301 71 634±47 69±1 24 2 7.673 1.326 9.2 AR4-A 22 399 65 437±26 22±2 16 5 5.642 1.337 7.2 AR4-B 22 399 136 477±4 28±1 17 11 6.652 1.378 5.9 AR4-C 22 399 65 537±12 32±1 15 4 6.199 1.363 5.9 AR4-D 22 399 34 540±7 37±1 18 2 6.926 1.38 9 AR4-E 22 399 96 520±12 44±2 23 4 6.336 1.388 5.4 AR4-F 22 399 53 609±32 61±2 23 3 6.744 1.349 6.9 AR5-A 22 480 48 467±15 25±2 16 4 4.964 1.414 17.3* AR5-B 22 480 21 506±1 36±1 20 3 5.455 1.394 6.2 AR5-C 22 480 91 525±12 47±1 24 3 7.492 1.404 3.9 AR5-D 22 480 143 567±14 55±2 24 4 7.645 1.428 5.2 AR5-E 22 480 80 587±16 64±2 26 3 6.154 1.39 5 AR5-F 22 480 79 627 94 35 1 5.376 1.275* 6.5 BH1b 22 182 461±21 20±3 10 1 5.227 1.217 4.1 BH1c 22 182 39 3 9.745 1.355 6.2 BH1d 22 182 28 2 5.503 1.22 5.3 BH1e 22 182 18 2 8.073 1.259 3.5* BH3b 22 76 34 481±27 24±3 12 3 10.485 1.245 20.6 BH3c 22 76 27 2 10.105 1.278 14.2 BH3d* 22 76 6 1* 7.626* 1.188* 10.8* BH6a 22 111 48 491±19 29±7 14 1 9.693 1.294 10.6 BH6b 22 111 28 2 4.96 1.178 9.6 BH6c 22 111 38 2 9.102 1.242 12.6 BH2b 22 196 32 536±22 35±4 14 1 11.59* 1.313 8.5 BH2c 22 196 38 2 6.376 1.258 10.2 BH2d 22 196 39 2 6.323 1.246 6.6 BH2e 22 196 31 1 10.186* 1.363* 6.5 BH5a 22 311 86 559±32 48±12 19 1 14.386* 1.448* 5.8 BH5b 22 311 41 1 8.028 1.288 6.9 BH5c 22 311 29 1 5.75 1.294 4.5 BH5d 22 311 30 1 7.609 1.365 4.5 BH4b 22 468 55 536±17 44±5 19 1 6.328 1.355 5 BH4c 22 468 53 2 6.347 1.404 3.9 BH4d 22 468 29 3 8.207 1.41 5.1 BH4e 22 468 50 1 6.938 1.423 2.9 AR6-T1 15 170 15 418±29 13±3 7±3 3 3.348 1.23 17.3* AR6-T2 15 170 22 369±23 15±2 11±1 3 3.856 1.235 10.1 AR6-T3 15 170 33 391±32 18±3 12±1 3 3.485 1.24 8.9 AR6-T4 15 170 31 467±67 32±9 18±1 2 3.442 1.243 8.9 AR27-T16 18 166 20 527±34 28±3 11±0 2 5.188 1.246 15.7* AR27-T18 18 166 30 447±47 23±4 13±0 2 4.197 1.249 8.7 AR27-T19 18 166 34 453±0 24±1 13±0 2 4.917 1.29 8.6 AR27-T20 18 166 22 481±47 28±4 14±1 2 4.795 1.267 6.9 AR27-T21 18 166 21 467±33 30±4 16±0 2 6.612 1.338 9.6 AR27-T22 18 166 44 517±17 46±4 17±0 2 3.944 1.252 7.7 AR27-T23 18 166 42 477±44 35±5 19±1 2 5.491 1.277 7.7 AR12-T6 25 216 6 447±87 16±5 7±0 2 7.651 1.263 20.7* AR12 -T7 25 216 33 547±0 27±1 10±0 2 8.314 1.283 13.5 AR10-12-T8 25 216 9 534±54 28±3 12±1 2 10.671 1.329 13.4* AR10-T9 25 216 24 567±20 35±1 13±0 2 9.331 1.329 8.6 AR12-T10 25 216 58 534±14 33±1 14±0 2 11.383 1.346 12.4 AR12-T11 25 216 61 494±14 29±1 14±0 2 8.821 1.297 8.5 AR10-12-T12 25 216 17 500±7 30±1 14±0 2 10.574 1.291 17.4* AR12-T13 25 216 24 554±7 37±1 15±0 2 8.598 1.313 9.2 AR12-T14 25 216 63 514±34 33±4 15±0 2 10.709 1.289 6.3 AR12-T15 25 216 25 540±20 36±2 15±0 2 9.941 1.321 7.3