Rapid ocean acidification and protracted Earth system recovery followed the end-Cretaceous Chicxulub impact

J.W.B.R. was supported by ERC Starting Grant 805246 OldCO2NewArchives.Mass extinction at the Cretaceous–Paleogene (K-Pg) boundary coincides with the Chicxulub bolide impact and also falls within the broader time frame of Deccan trap emplacement. Critically, though, empirical evidence as to how either of these factors could have driven observed extinction patterns and carbon cycle perturbations is still lacking. Here, using boron isotopes in foraminifera, we document a geologically rapid surface-ocean pH drop following the Chicxulub impact, supporting impact-induced ocean acidification as a mechanism for ecological collapse in the marine realm. Subsequently, surface water pH rebounded sharply with the extinction of marine calcifiers and the associated imbalance in the global carbon cycle. Our reconstructed water-column pH gradients, combined with Earth system modeling, indicate that a partial ∼50% reduction in global marine primary productivity is sufficient to explain observed marine carbon isotope patterns at the K-Pg, due to the underlying action of the solubility pump. While primary productivity recovered within a few tens of thousands of years, inefficiency in carbon export to the deep sea lasted much longer. This phased recovery scenario reconciles competing hypotheses previously put forward to explain the K-Pg carbon isotope records, and explains both spatially variable patterns of change in marine productivity across the event and a lack of extinction at the deep sea floor. In sum, we provide insights into the drivers of the last mass extinction, the recovery of marine carbon cycling in a postextinction world, and the way in which marine life imprints its isotopic signal onto the geological record.Publisher PDFPeer reviewe

Natural parenting : back to basics in infant care

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A História da Alimentação: balizas historiográficas

Os M. pretenderam traçar um quadro da História da Alimentação, não como um novo ramo epistemológico da disciplina, mas como um campo em desenvolvimento de práticas e atividades especializadas, incluindo pesquisa, formação, publicações, associações, encontros acadêmicos, etc. Um breve relato das condições em que tal campo se assentou faz-se preceder de um panorama dos estudos de alimentação e temas correia tos, em geral, segundo cinco abardagens Ia biológica, a econômica, a social, a cultural e a filosófica!, assim como da identificação das contribuições mais relevantes da Antropologia, Arqueologia, Sociologia e Geografia. A fim de comentar a multiforme e volumosa bibliografia histórica, foi ela organizada segundo critérios morfológicos. A seguir, alguns tópicos importantes mereceram tratamento à parte: a fome, o alimento e o domínio religioso, as descobertas européias e a difusão mundial de alimentos, gosto e gastronomia. O artigo se encerra com um rápido balanço crítico da historiografia brasileira sobre o tema

Biomarker indicies from DSDP Site 94-608

These files pertain to biomarker data data from Ocean Drilling Program (ODP) Site 982 and Deep Sea Drilling Project (DSDP) Site 608. For each site, the fractional abundances of isoprenoidal and branched glycerol dialkyl glycerol tetraethers (GDGTs) are included in addition to the various indices discussed in the paper. These indices include the sea surface temperature proxy TEX86, as well as others used to test the fidelity of this sea surface signal (Methane Index, MI; Branched Isoprenoidal Tetratether Index, BIT; and the Ring Index, RI). Alkenone data are also included, which are used to calculate the UK'37 index and related SST estimates

Fractional abundances of isoprenoidal and branched glycerol dialkyl glycerol tetraethers (GDGTs) from different holes of ODP Site 162-982

These files pertain to biomarker data data from Ocean Drilling Program (ODP) Site 982 and Deep Sea Drilling Project (DSDP) Site 608. For each site, the fractional abundances of isoprenoidal and branched glycerol dialkyl glycerol tetraethers (GDGTs) are included in addition to the various indices discussed in the paper. These indices include the sea surface temperature proxy TEX86, as well as others used to test the fidelity of this sea surface signal (Methane Index, MI; Branched Isoprenoidal Tetratether Index, BIT; and the Ring Index, RI). Alkenone data are also included, which are used to calculate the UK'37 index and related SST estimates

Fractional abundances of isoprenoidal and branched glycerol dialkyl glycerol tetraethers (GDGTs) from DSDP Site 94-608

These files pertain to biomarker data data from Ocean Drilling Program (ODP) Site 982 and Deep Sea Drilling Project (DSDP) Site 608. For each site, the fractional abundances of isoprenoidal and branched glycerol dialkyl glycerol tetraethers (GDGTs) are included in addition to the various indices discussed in the paper. These indices include the sea surface temperature proxy TEX86, as well as others used to test the fidelity of this sea surface signal (Methane Index, MI; Branched Isoprenoidal Tetratether Index, BIT; and the Ring Index, RI). Alkenone data are also included, which are used to calculate the UK'37 index and related SST estimates

Biomarker indicies proxies from different Holes of ODP Site 162-982

These files pertain to biomarker data data from Ocean Drilling Program (ODP) Site 982 and Deep Sea Drilling Project (DSDP) Site 608. For each site, the fractional abundances of isoprenoidal and branched glycerol dialkyl glycerol tetraethers (GDGTs) are included in addition to the various indices discussed in the paper. These indices include the sea surface temperature proxy TEX86, as well as others used to test the fidelity of this sea surface signal (Methane Index, MI; Branched Isoprenoidal Tetratether Index, BIT; and the Ring Index, RI). Alkenone data are also included, which are used to calculate the UK'37 index and related SST estimates