The planktic foraminiferal B/Ca proxy for seawater carbonate chemistry: A critical evaluation

The ratio of boron to calcium (B/Ca) in the carbonate tests of planktic foraminifers has been proposed as a proxy for surface ocean pH or carbonate ion concentration ([CO32−]), with a possible secondary influence of temperature. In both cultured and wild specimens, B/Ca generally increases with [B(OH)4−/HCO3−], consistent with the proxy's theoretical basis. However, close examination of the available data reveals that calibrations using the empirical boron partition coefficient, KD=[B/Ca]calcite/[B(OH)4−/HCO3−]seawater, can be driven by independent relationships between [B(OH)4−/HCO3−] and other environmental parameters, not by B/Ca itself. If the influence of B/Ca on a calibration is negligible, it follows that combining that calibration with down-core B/Ca can not yield new information about past ocean conditions. In this study, we evaluate existing calibrations and down-core records with the aim of establishing a framework that allows consistent calibration methods to yield accurate proxy reconstructions from the fossil record. While many issues still need to be addressed, B/Ca does respond to seawater chemistry, and does change across some major climate transitions. Because it may provide insight into major carbon cycle perturbations, we make specific recommendations on how to tackle current uncertainties and develop B/Ca into a more robust proxy

Boron in Foraminiferal Calcite as an Indicator of Seawater Carbonate Chemistry

Foraminifera are unicellular organisms with a wide marine distribution. Many species secrete carbonate tests whose physical and chemical nature reflect the seawater conditions in which they grow. Thus, fossil tests preserved on the sea floor represent an archive that may be used to investigate the composition of ancient seawater. With the aim of improving our understanding of past ocean-climate links, I have tested proxies for seawater composition in the modern ocean and applied them to a key period in Earth history. The ratio of boron to calcium (B/Ca) in the calcite tests of planktic foraminifers has previously been suggested as a proxy for past seawater carbonate chemistry, but controls on B incorporation are not yet clear. The theoretical basis for this proxy is rooted in the pH-dependent concentration of dissolved borate (B(OH)_4-) and its subsequent incorporation into foraminiferal calcite. In this thesis, I present: 1) new insights into the environmental controls on B/Ca revealed by culture experiments with living foraminifers, and 2) new reconstructions of past seawater chemistry during the last deglaciation based on B/Ca of fossil calcite from deep sea sediments. To test environmental controls on B incorporation, I performed several culture experiments that quantified the effects of pH, temperature, salinity, dissolved boron and inorganic carbon concentrations on the calcite tests of the planktic foraminifer species O. universa, G. sacculifer, and G. ruber (pink). In these experiments, B/Ca increases with pH (lower [HCO_3-], higher [CO2_3-] and [B(OH)_4-]) and salinity, but not with temperature. Thus, normalizing B/Ca data to a constant salinity (e.g., S=35) should improve our ability to isolate the carbonate chemistry signal in B/Ca paleo-records and samples from different ocean sites. In addition, B/Ca decreases with total dissolved inorganic carbon (DIC) at constant pH (higher [HCO_3-] and [CO2_3-], constant [B(OH)_4-]), which suggests competition between aqueous boron and carbon species for inclusion into the calcite lattice. While different cultured species exhibit similar B/Ca behavior in response to salinity, temperature, and pH changes, their absolute B/Ca values are offset under identical seawater conditions. Thus, B/Ca is both a function of environmental parameters that exert strong influence on test composition as well as biological processes that result in species offsets. To determine whether these culture calibrations are applicable in the open ocean, I used equations relating the B/Ca of cultured foraminifers with experimental seawater properties to predict B/Ca of wild specimens derived from sediment core-tops. Most measured core-top values for O. universal and G. sacculifer are similar to values predicted by culture calibrations (average offsets are 4 and 15 μmol mol^-1, respectively) but values predicted for coretop G. ruber deviate by up to 60 μmol mol^-1 from predicted values. The greater discrepancy observed for core-tops may suggest that our experiments still fall short of identifying all environmental controls on B/Ca and/or that we need to revisit the growth conditions assumed for planktic foraminifers, in particular the depth habitat of G. ruber. Further, an evaluation of planktic foraminiferal downcore data shows that B/Ca in planktic foraminifers is not sufficiently sensitive to surface ocean carbonate chemistry to permit reconstruction of Pleistocene atmospheric CO2 changes. However, B/Ca may serve as a useful proxy in environments that experienced large carbonate system changes, such as upwelling zones, or large events such as those during the Paleocene-Eocene. In contrast to planktic foraminifers, B/Ca of benthic foraminifer tests appears to respond to deep-water carbonate saturation state (ΔCO2_3-). B/Ca of the benthic species Cibicidoides wuellerstorfi increases linearly with ΔCO2_3- in all major ocean basins, as demonstrated in the modern core-top calibration of Yu and Elderfield (2007). To gain insight into carbon storage in the deep ocean across the last glacial termination, I investigated the B/Ca composition of C. wuellerstorfi in a sediment core from New Zealand's Bay of Plenty, located at a depth of 1,627 meters. The resulting reconstruction indicates that ΔCO2_3- changed up to 30 μmol kg^-1 across the deglaciation. Combined with benthic δ^13C and independent paleo-O_2 estimates, the [CO2_3-] record indicates increased storage of CO_2 in the deep ocean during the LGM, with major roles for the biologic pump and carbonate compensation

Controls on boron incorporation in cultured tests of the planktic foraminifer Orbulina universa

Culture experiments with living planktic foraminifers reveal that the ratio of boron to calcium (B/Ca) in Orbulina universa increases from 56 to 92 μmol mol−1 when pH is raised from 7.61+/–0.02 to 8.67+/–0.03 (total scale). Across this pH range, the abundances of carbonate, bicarbonate, and borate ions also change (+530, −500, and +170 μmol kg−1, respectively). Thus specific carbonate system control(s) on B/Ca remain unclear, complicating interpretation of paleorecords. B/Ca in cultured O. universa also increases with salinity (55–72 μmol mol−1 from 29.9–35.4‰) and seawater boron concentration (62–899 μmol mol−1 from 4–40 ppm B), suggesting that these parameters may need to be taken into account for paleorecords spanning large salinity changes (~ 2‰) and for samples grown in seawater whose boron concentration ([B]SW) differs from modern by more than 0.25 ppm. While our results are consistent with the predominant incorporation of the charged borate species B(OH)4−into foraminiferal calcite, the behavior of the partition coefficient KD (defined as [B/Ca]calcite/[B(OH)4−/HCO3−]seawater) cannot be explained by borate incorporation alone, and suggests the involvement of other pH-sensitive ions such as CO3 2− For a given increase in seawater B(OH)4−, the corresponding increase in B/Ca is stronger when B(OH)4− is raised by increasing [B]SW than when it is raised by increasing pH. These results suggest that B incorporation controls should be reconsidered. Additional insight is gained from laser-ablation ICP-MS profiles, which reveal variable B/Ca distributions within individual shells

The Iowa Homemaker vol.28, no.3

Memo to a Freshman, page 2 Money Planning Can Be Fun, Mary Alice Halverson, page 3 If Marriage Is in Your Future, Jo Ann Breckenridge, page 4 There’s Excitement Ahead, Katherine Williams, page 6 Activities Point Up Fun for Free Time, Margaret Edgar, page 7 Faculty Suggests Electives, Peggy Ann Krenek, page 8 All You Have To Do Is Eat, Janet Sutherland, page 9 Meet Your Counselors, Elinor Chase, page 10 Vicky, Jo Ann Breckenridge, page 12 What’s New, Peggy Ann Krenek, page 17 Testing Bureau, Barbara Allen, page 19 Keeping Up With Today, Mary West, page 2

The Iowa Homemaker vol.28, no.1

Housemothers Enjoy Personal Ties, Janet Sutherland, page 2 Your Hope Chest Plans, Jo Ann Breckenridge, page 3 Select Your Electives Now, Barbara Parson, page 4 With Spring – Sport’s The Thing, Barbara Allen, page 5 You Can Make Packing Fun, Patricia Close, page 7 Vicky Boasts – Bring On The Rain, Katherine Williams, page 8 Wee Listeners Join Radio Fans, Lee Ann Smiley, page 10 Zipper History Has Ups and Downs, Margaret Leveson, page 12 Simple Corsages That You Can Make, Emogene Olson, page 15 Keeping Up with Today, Mary West, page 1

The Influence of Salinity on Mg/Ca in Planktic Foraminifers – Evidence from Cultures, Core-top Sediments and Complementary δ18O

The Mg/Ca ratio in foraminiferal calcite is one of the principal proxies used for paleoceanographic temperature reconstructions, but recent core-top sediment observations suggest that salinity may exert a significant secondary control on planktic foraminifers. This study compiles new and published laboratory culture experiment data from the planktic foraminifers Orbulina universa, Globigerinoides sacculifer and Globigerinoides ruber, in which salinity was varied but temperature, pH and light were held constant. Combining new data with results from previous culture studies yields a Mg/Ca-sensitivity to salinity of 4.4 ± 2.3%, 4.7 ± 1.2%, and 3.3 ± 1.7% per salinity unit (95% confidence), respectively, for the three foraminifer species studied here. Comparison of these sensitivities with core-top data suggests that the much larger sensitivity (27 ± 4% per salinity unit) derived from Atlantic core-top sediments in previous studies is not a direct effect of salinity. Rather, we suggest that the dissolution correction often applied to Mg/Ca data can lead to significant overestimation of temperatures. We are able to reconcile culture calibrations with core-top observations by combining evidence for seasonal occurrence and latitude-specific habitat depth preferences with corresponding variations in physico-chemical environmental parameters. Although both Mg/Ca and δ18O yield temperature estimates that fall within the bounds of hydrographic observations, discrepancies between the two proxies highlight unresolved challenges with the use of paired Mg/Ca and δ18O analyses to reconstruct paleo-salinity patterns across ocean basins. The first step towards resolving these challenges requires a better spatially and seasonally resolved δ18Osw archive than is currently available. Nonetheless, site-specific reconstructions of salinity change through time may be valid

The Iowa Homemaker vol.3, no.9

Table of Contents Books – Why Not? by Charles H. Brown, page 3 A Visit to the Bazaars of Stamboul by Eda Lord Murphy, page 4 Glimpses in a Christmas Shop by Helen Brennan, page 4 That Roast Fowl by Viola M. Bell, page 5 Echoes from State Home Economics Convention by Katherine Goeppinger, page 6 Toys That Interest by Bertha Mann, page 7 Christmas Festivities in Foreign Lands by Barbara Dewell, page 8 Christmas Dinner for Two – by Louise Doole, page 9 Italian Hemstitching by Lora Ann Stanke, page 10 Eda Lord Murphy Writes from Constantinople by Eda Lord Murphy, page 10 Who is Responsible for the Child? by Minne Elisabeth Allen, page 11 Holiday Sweets by Alma Riemenschneider, page 12 The Perfect Guest by Lucile Barta, page 12 The Evolution of Home Economics at Iowa State by Ruth Elaine Wilson, page 13 Baskets Which Will Lead Long Useful Lives by Viola Jammer, page 14 Who’s There and Where by Helen I. Putnam, page 1

Formar bem as mães para criar e educar boas crianças: as revistas portuguesas de educação familiar e a difusão da maternidade científica (1945-1958)

Este artigo tem como principal objetivo contribuir para a compreensão do processo de construção da maternidade científica em Portugal. Neste sentido, foi analisado um conjunto de artigos (n=628), publicados em revistas de educação familiar, entre 1945 e 1958. A análise realizada permitiu compreender que as revistas analisadas contribuem para a difusão da maternidade científica, ou seja, da ideia de que a aquisição de conhecimento científico sobre a criação e educação das crianças é elemento indispensável ao adequado exercício da função maternal. Observou-se, ainda, a existência de diferentes estratégias de educação para a maternidade, às quais está subjacente um elemento de classe, assim como diferentes níveis de adesão, por parte das mulheres, à concepção de maternidade científica

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London