Paleoenvironmental responses to Late Cretaceous Oceanic Anoxic Event 2 on the Kerguelen Plateau

Oceanic Anoxic Event 2 (OAE-2, ~94 Ma: late Cretaceous) was characterized by a perturbation in seawater chemistry, an expansion of marine anoxia and euxinia, an increase in marine organic-carbon burial, a decrease in atmospheric pCO2 during an interval of high global temperatures, an extinction event among marine organisms, and changes in weathering intensity. However, many of the most detailed studies of OAE-2 are from the northern hemisphere, and consequently how global environmental changes were expressed at the local and regional scale in the southern hemisphere is poorly understood. A detailed geochemical, petrographic and micropalaeontological dataset from Ocean Drilling Program Site 1138 on the Kerguelen Plateau, southern Indian Ocean (53.5oS paleolatitude), identifies OAE-2 from a 3\u2030 positive carbon-isotope excursion (CIE) and from high-resolution nannofossil biostratigraphy. An enrichment of organic carbon (to ~15%) corresponds with a shift towards locally sub-oxic/anoxic conditions, as recorded by trace-metal enrichments and molybdenum-isotope compositions. The redox changes coincide stratigraphically with an abrupt decline in the delivery of highly weathered detrital material and terrestrial organic matter to Site 1138. A rapid relative sea-level rise occurring around the onset of OAE-2 could have reduced the input of highly weathered detrital sediments, while moving the local seafloor deeper into an oxygen minimum zone impinging on the margins of the Kerguelen Plateau. Alternatively, or additionally, intensified mid-latitude hydrological cycling in the early stages of OAE-2 could have rapidly destabilized terrestrial sediments from sub-aerial landmasses on the Kerguelen Plateau. In either case, the new datasets highlight the abrupt nature of the palaeoenvironmental response to OAE-2 in the mid-latitude southern hemisphere

Climate-driven coupling of weathering and carbon burial across the Cenomanian: Turonian boundary at ODP Site 1138 (Kerguelen Plateau)

Despite its assumed global nature, there are few detailed stratigraphic records [...]

A Southern Hemisphere record of global trace-metal drawdown and orbital modulation of organic-matter burial across the Cenomanian–Turonian boundary (ODP Site 1138, Kerguelen Plateau)

Despite its assumed global nature, there are very few detailed stratigraphic records of the late Cenomanian to the early Turonian Oceanic Anoxic Event (OAE) 2 from the Southern Hemisphere. A highly resolved record of environmental changes across the Cenomanian–Turonian boundary interval is presented from Ocean Drilling Program Site 1138 on the central Kerguelen Plateau (southern Indian Ocean). The new data lead to three key observations. Firstly, detailed bio- and chemostratigraphy indicate that the record of OAE-2 is not complete, with a hiatus spanning the onset of the event. A decrease in glauconite and highly weathered clays after the onset of OAE-2 marks the end of the hiatus interval, which can be explained by a relative sea-level rise that increased sediment accommodation space on the Kerguelen Plateau margin. This change in depositional environment controlled the timing of the delayed peak in organic-matter burial during OAE-2 at Site 1138 compared with other OAE-2 locations worldwide. A second key observation is the presence of cyclic fluctuations in the quantity and composition of organic matter being buried on the central Kerguelen Plateau throughout the latter stages of OAE-2 and the early Turonian. A close correspondence between organic matter, sedimentary elemental compositions and sediments recording sea-floor oxygenation suggests that the cycles were mainly productivity-driven phenomena. Available age-control points constrain the periodicity of the coupled changes in sedimentary parameters to ~15–50 ka, suggesting a link between carbon burial and astronomically forced climatic variations (precession or obliquity) in the Southern Hemisphere mid-latitudes both during, and after, OAE-2: fluctuations that were superimposed on the impact of global-scale processes. Finally, trace-metal data from the non-sulphidic black shale unit at Site 1138 provide the first evidence from outside of the proto-North Atlantic region for a global drawdown of seawater trace-metal (Mo) inventories during OAE-2.</p

Geochemical data from the Cenomanian-Turonian interval of ODP Hole183-1138A

Geochemical data from Ocean Drilling Program Site 1138A, core 69, spanning the Cenomanian–Turonian boundary interval (~94 Ma). The data were generated from marine sediment in the archive half of the core, which was opened and sampled for this project following approval from the IODP curatorial advisory board. The data consist of: (i) Bulk organic geochemistry (total organic carbon, hydrogen and oxygen indexes, total inorganic carbon) measured by Rock Eval pyrolysis and coulormat titration; (ii) Bulk organic carbon isotopes, measured on decarbonated sediments; (iii) Bulk sediment elemental concentrations measured by ICP-MS; (iv) Bulk sediment molybdenum isotopes, measured by MC-ICP-MS; (v) n-alkane compound-specific carbon isotopes measured by GCMS-IRMS; (vi) Maceral assemblage compositions, measured by visual petrography

Nanosensors based detection of foodborne pathogens

Contaminated food cause by pathogens is one of the main reasons incidences of human diseases cases all around the world. Typically, most foodborne contaminants caused by bacteria, parasites and virus that have a major economic impact. It is important to restrain them, thus early detection system is very crucial. Several methods have been explored for the detection and identification of these microorganisms in food samples. However, some of these methods are involves complicated sample pre-treatment, laborious, time-consuming and are not suitable for on-site applications. Therefore, it is very important to develop rapid, sensitive, selective and more approachable detection methods. Recently, biosensors have been explored as alternative approach method and considered as one of most rapid and on-site applicable methods. Advancements in nanotechnology have provided biosensor with novel architecture by using nanoscaled materials and structures for enhance the biosensing performance. This article highlights the significant progress of nanosensor based on electrochemical and optical, and other types of nanosensors with the focus on the foodborne pathogen detection