Upper ocean oxygenation dynamics from I/Ca ratios during the Cenomanian-Turonian OAE 2

Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 30 (2015): 510–526, doi:10.1002/2014PA002741.Global warming lowers the solubility of gases in the ocean and drives an enhanced hydrological cycle with increased nutrient loads delivered to the oceans, leading to increases in organic production, the degradation of which causes a further decrease in dissolved oxygen. In extreme cases in the geological past, this trajectory has led to catastrophic marine oxygen depletion during the so-called oceanic anoxic events (OAEs). How the water column oscillated between generally oxic conditions and local/global anoxia remains a challenging question, exacerbated by a lack of sensitive redox proxies, especially for the suboxic window. To address this problem, we use bulk carbonate I/Ca to reconstruct subtle redox changes in the upper ocean water column at seven sites recording the Cretaceous OAE 2. In general, I/Ca ratios were relatively low preceding and during the OAE interval, indicating deep suboxic or anoxic waters exchanging directly with near-surface waters. However, individual sites display a wide range of initial values and excursions in I/Ca through the OAE interval, reflecting the importance of local controls and suggesting a high spatial variability in redox state. Both I/Ca and an Earth System Model suggest that the northeast proto-Atlantic had notably higher oxygen levels in the upper water column than the rest of the North Atlantic, indicating that anoxia was not global during OAE 2 and that important regional differences in redox conditions existed. A lack of correlation with calcium, lithium, and carbon isotope records suggests that neither enhanced global weathering nor carbon burial was a dominant control on the I/Ca proxy during OAE 2.Z.L. thanks NSF OCE 1232620. J.D.O. is supported by an Agouron Postdoctoral Fellowship. T.W.L. acknowledges support from the NSF-EAR and NASA-NAI. A.R. thanks the support of NERC via NE/J01043X/1.2015-11-1

FLOW CYTOMETRY IN MYELODYSPLASTIC SYNDROME- CORRELATION WITH CYTOMORPHOLOGY RESULTS

Introduction: In the absence of significant dysplasia in suspected myelodysplastic syndrome (MDS), flow cytometry (FC) analysis helps to distinguish clonal cytopenia. The aim of the study was to analyse the concordance of cytomorphological characteristics and flow cytometry in patients with newly diagnosed MDS in KB Merkur in the period from March 2016 to April 2023. Methods: We analyzed bone marrow FC in 69 patients (38 men, 31 women) who were diagnosed with MDS based on bone marrow morphology. Results: In 57 patients (82%), the morphological diagnosis of MDS was also confirmed in the flow cytometry findings. In 11 (91%) of a total of 12 patients in whom the FC analysis did not prove MDS, no blasts were observed in the cytological findings. The expression of CD34, CD117, CD13 and CD33 (cut off 20%) was analyzed in 57 patients in whom MDS was suspected in the myelogram and FC . CD117 and CD33 did not differ between groups, regardless of MDS subtype. CD34 and CD13 was statistically significantly higher in high-risk MDS than in low-risk MDS. There was no statistically significant difference in the level of hemoglobin and expression of CD antigen, while the level of platelets correlated negatively with the level of CD117, CD13 and CD34. The expression of CD34 positively correlated with the level of C reactive protein. Conclusions: Flow cytometry in MDS is a valuable additional method in discriminating MDS from other forms of cytopenia to improve both diagnosis and prognosis, but there is a need to establish standard techniques in everyday use

Geochemical characterisation and of black shales from the Tarfaya-Layoune Basin (SW Morocco) : Implications for palaeoenvironmental controls on sulfurisation process of the organic matter

Organic geochemical and petrological investigations were carried out on Cenomanian/Turonian black shales from three sample sites in the Tarfaya Basin (SW Morocco) to characterize the sedimentary organic matter. These black shales have a variable bulk and molecular geochemical composition reflecting changes in the quantity and quality of the organic matter. High TOC contents (up to 18wt%) and hydrogen indices between 400 and 800 (mgHC/gTOC) indicate hydrogen-rich organic matter (Type I-II kerogen) which qualifies these laminated black shale sequences as excellent oil-prone source rocks. Low Tmax values obtained from Rock-Eval pyrolysis (404-425°C) confirm an immature to early mature level of thermal maturation. Organic petrological studies indicate that the kerogen is almost entirely composed of bituminite particles. These unstructured organic aggregates were most probably formed by intensive restructuring of labile biopolymers (lipids and/or carbohydrates), with the incorporation of sulphur into the kerogen during early diagenesis. Total lipid analyses performed after desulphurization of the total extract shows that the biomarkers mostly comprise short-chain n-alkanes (C₁₆-C₂₂) and long-chain (C₂₅-C₃₅) n-alkanes with no obvious odd-over-even predominance, together with steranes, hopanoids and acyclic isoprenoids. The presence of isorenieratane derivatives originating from green sulphur bacteria indicates that dissolved sulphide had reached the photic zone at shallow water depths (~100m) during times of deposition. These conditions probably favoured intensive sulphurization of the organic matter. Flash pyrolysis GC-MS analysis of the kerogen indicates the aliphatic nature of the bulk organic carbon. The vast majority of pyrolysis products are sulphur-containing components such as alkylthiophenes, alkenylthiophenes and alkybenzothiophenes. Abundant sulphurization of the Tarfaya Basin kerogen resulted from excess sulphide and metabolizable organic matter combined with a limited availability of iron during early diagenesis. The observed variability in the intensity of OM sulphurization may be attributed to sea level-driven fluctuations in the palaeoenvironment during sedimentation

Geochemical characterization of Cenomanian/Turonian black shales from the Tarfaya basin (SW Morocco): relationships between palaeoenvironmental conditions and early sulphurization of sedimentary organic matter

Organic geochemical and petrological investigations were carried out on Cenomanian/Turonian black shales from three sample sites in the Tarfaya Basin (SW Morocco) to characterize the sedimentary organic matter. These black shales have a variable bulk and molecular geochemical composition reflecting changes in the quantity and quality of the organic matter. High TOC contents (up to 18wt%) and hydrogen indices between 400 and 800 (mgHC/gTOC) indicate hydrogen‐rich organic matter (Type I‐II kerogen) which qualifies these laminated black shale sequences as excellent oil‐prone source rocks. Low Tmax values obtained from Rock‐Eval pyrolysis (404–425 MC) confirm an immature to early mature level of thermal maturation. Organic petrological studies indicate that the kerogen is almost entirely composed of bituminite particles. These unstructured organic aggregates were most probably formed by intensive restructuring of labile biopolymers (lipids and/or carbohydrates), with the incorporation of sulphur into the kerogen during early diagenesis. Total lipid analyses performed after desulphurization of the total extract shows that the biomarkers mostly comprise short‐chain n‐alkanes (C16–C22) and long‐chain (C25–C35) n‐alkanes with no obvious odd‐over‐even predominance, together with steranes, hopanoids and acyclic isoprenoids. The presence of isorenieratane derivatives originating from green sulphur bacteria indicates that dissolved sulphide had reached the photic zone at shallow water depths (∼100m) during times of deposition. These conditions probably favoured intensive sulphurization of the organic matter. Flash pyrolysis GC‐MS analysis of the kerogen indicates the aliphatic nature of the bulk organic carbon. The vast majority of pyrolysis products are sulphur‐containing components such as alkylthiophenes, alkenylthiophenes and alkybenzothiophenes. Abundant sulphurization of the Tarfaya Basin kerogen resulted from excess sulphide and metabolizable organic matter combined with a limited availability of iron during early diagenesis. The observed variability in the intensity of OM sulphurization may be attributed to sea level‐driven fluctuations in the palaeoenvironment during sedimentation