Carbon stable isotope record in the coral species Siderastrea stellata: A link to the Suess Effect in the tropical South Atlantic Ocean

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Coral skeletons are natural archives whose geochemical signatures provide insights into the tropical ocean history beyond the instrumental record. Carbon stable isotopes from coral skeletons (δ13Ccoral) have been used as a proxy for multiple variables on a seasonal basis. Long-term changes in coral δ13C could be related to the changing isotopic composition of the dissolved inorganic carbon (δ13CDIC). δ13CDIC in turn reflects changes in the δ13C of atmospheric CO2, which in the modern Earth system is governed primarily by anthropogenic injection of CO2 into the atmosphere – a process known as the Suess Effect. Here we report three δ13C coral-based records of Siderastrea stellata from the tropical South Atlantic. U-series dating for the colonies 12SFB-1, 13SS-1 and 13SS-2 suggests these corals lived 13, 57 and 65 years, respectively. Short-term δ13C variations in their skeletal aragonite are dominated by interannual variation. All three δ13C records additionally exhibit an overall decreasing trend, with a depletion of about −0.0243 ± 0.0057‰·yr−1 (12SFB-1), −0.0208 ± 0.0007‰·yr−1 (13SS-1) and −0.0214 ± 0.0013‰·yr−1 (13SS-2). These rates of the coral records from Rocas Atoll are similar to the reported trend for the δ13C of atmospheric CO2 over the years 1960–1990 (−0.023 to −0.029‰·yr−1), and to the decreasing rates of global δ13CDIC. Our findings suggest that multiple δ13C coral-based records are required for confidently identifying local changes in the δ13CDIC of the ocean. This information, in turn, can be used to infer changes in the δ13C of the atmospheric CO2 composition and provide valuable information about recent changes on the carbon biogeochemical cycle during the Anthropocene epoch.NSP acknowledges the National Counsel of Technological and Scientific Development (CNPq) for a Post-Doctoral Scholarship Proc. no 150405/2015-4. We thank the chief of the Biological Reserve of Rocas Atoll, Maurizélia de Brito Silva and the field team Tiago Albuquerque, Miguel Miranda, Mirella B. Costa and Eduardo Macêdo, for the great assistance in this study. We thank Gilsa Santana, Vilma Sobral (NEG-LABISE, Brazil) and Bo Petersen (University of Copenhagen) for assisting in stable isotope measurements. We are thankful for the critical and constructive comments of the anonymous reviewers. The 2013 field work was partially supported by National Geographic Waitt Foundation grant W21-12 to K.H.K. and R.K.P.K. U-Th dating was supported by grants from Ministry of Science and Technology (MOST) (105-2119-M-002-001, 106-2628-M-002-013 to C.-C.S.) and the National Taiwan University (105R7625 to C.-C.S.). This manuscript is the scientific contribution no 288 of the NEG-LABISE, UFPE, a contribution of the Reef Ecosystems Working Group of the INCT Ambientes Marinhos Tropicais (InctAmbTropic – CNPq #565.054/2010-4) and represents contribution 5470 of the University of Maryland Center for Environmental Science

Mercury Spikes Indicate a Volcanic Trigger for the Late Ordovician Mass Extinction Event: An Example from a Deep Shelf of the Peri-Baltic Region.

The Late Ordovician mass extinction (LOME) was the second largest Phanerozoic crisis, but its cause remains elusive. Several triggering mechanisms have been proposed over the years, including bioevolutionary events, oceanographic changes, and geotectonic processes. Here, we report the presence of Hg spikes in the Zbrza PIG-1 borehole from the Upper Ordovician deep shelf sections of the peri-Baltic region. A strong positive anomaly in the lower late Katian (Hg/TOC = 2537.3 ppb/wt%) was noted. No correlation between Hg and TOC (R² = 0.07) was distinguished in the Hirnantian, although several positive anomalies were found. Because the Hg/Mo ratio showed trends very similar to those of Hg/TOC, it seems likely that TOC values reflect the redox conditions. In order to evaluate the role of anoxia in levels of Hg enrichment several redox indicators were measured. These showed that the elevated mercury values in the Hirnantian are not caused by anoxia/euxinia because euxinic biomarkers (maleimides and aryl isoprenoids) are present in very low abundance and pyrite framboids are absent. In total, positive Hg/TOC anomalies occur in the lower late Katian, at the Katian - Hirnantian boundary, and in the late Hirnantian. The lack of a strong Hg/TOC correlation, Ni enrichments, and the absence of 'anoxic indicators' (no biomarkers, no framboids, low Mo concentration) at these levels, supports the interpretation that Hg enrichment is due to enhanced environmental loading. We conclude that our Hg and Hg/TOC values were associated with volcanic pulses which triggered the massive environmental changes resulting in the Late Ordovician mass extinction

Effect of garlic on cardiovascular disorders: a review

Garlic and its preparations have been widely recognized as agents for prevention and treatment of cardiovascular and other metabolic diseases, atherosclerosis, hyperlipidemia, thrombosis, hypertension and diabetes. Effectiveness of garlic in cardiovascular diseases was more encouraging in experimental studies, which prompted several clinical trials. Though many clinical trials showed a positive effect of garlic on almost all cardiovascular conditions mentioned above, however a number of negative studies have recently cast doubt on the efficary of garlic specially its cholesterol lowering effect of garlic. It is a great challenge for scientists all over the world to make a proper use of garlic and enjoy its maximum beneficial effect as it is the cheapest way to prevent cardiovascular disease. This review has attempted to make a bridge the gap between experimental and clinical study and to discuss the possible mechanisms of such therapeutic actions of garlic

Mid to late 20th century freshening of the western tropical South Atlantic triggered by southward migration of the Intertropical Convergence Zone

In the tropical Atlantic Ocean, the Intertropical Convergence Zone (ITCZ) is an important climate feature controlled by the interhemispheric sea surface temperature (SST) gradient, and greatly influences rainfall patterns over the adjacent continents. To better understand ITCZ dynamics in the context of past and future climate change, long-term oceanic records are needed, but observational data are limited in temporal extent. Shallow-water corals provide seasonally-resolved archives of climate variability over the tropical ocean. Here we present seasonally-resolved records of stable oxygen (δ18O) and carbon (δ13C) isotope values of a Siderastrea stellata coral from northeastern Brazil (Maracajaú, ~5°S). We show that the long-term trends in the record of coral δ18O values are not primarily driven by SST but by hydrological changes at the sea surface. Combining the record of coral δ18O values with instrumental SST, we present the first reconstruction of seawater δ18O changes (δ18Oseawater) in the western tropical South Atlantic back to the early 20th century, a parameter that is related to changes in sea surface salinity. The reconstructed δ18Oseawater changes indicate a prominent freshening between the mid-1940's and mid-1970's, which coincides with a weakening of the Atlantic interhemispheric SST gradient during this time interval. Our results suggest that the weakened Atlantic SST gradient resulted in a southward shift of the thermal equator that was accompanied by a southward migration of the ITCZ, resulting in freshening of the western tropical South Atlantic during the mid to late 20th century

Características de latossolos roxos desenvolvidos de rochas alcalinas e básicas de Jaboticabal, SP Characteristics of dusky red latosols developed from alcaline and basic rocks in Jaboticabal, SP

Comparou-se as características químicas, físicas e mineralógicas de Latossolos Roxos desenvolvidos de rocha alcalina (LRe) e de rocha eruptiva básica (LRd), da região de Jaboticabal, SP. Os resultados indicaram que o LRe apresenta-se num estádio de desenvolvimento, comparativamente, menos evoluído que o LRd, enquanto esse se apresenta com tendência para a maturidade. Os menores teores de argila e ferro total e maiores teores de saturação por bases, Ki e CTC da fração argila apresentados pelo LRe comprovam esta tendência. Conclui-se que a ocorrência de Latossolo Roxo eutrófico no campus da UNESP-Jaboticabal, pode estar associada a participação de rochas alcalinas na sua pedogênese.<br>A comparative study was carried out on chemical, physical and mineralogical characteristics of dusky red latosols originated from the weathering of alcaline (LRe) and basic eruptive rocks (LRd), of the Jaboticabal country Brazil The results showed that the LRe presented a younger development stage than LRd, while this soil showed a tendency to maturity. This trend was corraborated through the lower clay and total Fe2O3, contents and higher base saturation contents, Si2O/Al2O3 molecular ratio (Ki) and clay f ration CEC presented by LRe. It can be concluded that the occurrence of eutrophic dusky red latosols hi the UNESP-Jaboticabal campus may be due to the influence of alcaline rocks