Spatial heterogeneity of sources of branched tetraethers in shelf systems: The geochemistry of tetraethers in the Berau River delta (Kalimantan, Indonesia)

The bulk organic matter composition (total organic carbon (TOC) content and d13CTOC) and composition of isoprenoid and branched glycerol dialkyl glycerol tetraethers (GDGT) in surface sediments from 43 stations in the Berau River delta (east Kalimantan, Indonesia), including two coast-shelf transects and stations within the river mouth, were examined to reveal the spatial heterogeneity in these parameters in order to assess the impact of a tropical river loaded with suspended matter on the sedimentary organic matter in the shelf system. The high-resolution study showed that, despite the extensive transport of eroded soil material by the river to the sea, terrestrial organic matter and brGDGTs are only deposited on a relatively small part of the shelf. The concentrations of brGDGTs are highest (up to 120 µg g-1 TOC) in sediments deposited in and close to the mouth of the Berau River and their distribution indicates that they represent a mixture of soil-derived and river in-situ produced brGDGTs. Crenarchaeol concentrations reach 700 µg g-1 TOC in sediments deposited on the outer shelf due to Thaumarchaeotal production in shelf waters. This results in a strong gradient (0.93–0.03) in the BIT index, with high values in the river mouth and low values on the shelf. The decline in the BIT index is caused by both decreasing concentrations of the brGDGTs and increasing concentrations of crenarchaeol. The BIT index shows a highly significant but non-linear relationship with d13CTOC. On the shelf, in the area not under the direct influence of the Berau River, cyclic brGDGTs become relatively dominant, most probably due to in-situ production in the alkaline pore waters of the surface sediments. The spatial heterogeneity of sources of brGDGTs on the Berau shelf complicates the use of brGDGTs as temperature proxies. Application of the global soil calibration to sedimentary mixtures of brGDGTs in the river-influenced area of the shelf results in a severe underestimation of mean annual air temperature (MAT) by 6 °C. This is due to the mixed origin of the brGDGTs, which are not only derived from soil erosion but, likely, also from riverine production, as has been observed for other river systems.Comparison of the Berau shelf other shelf systems indicates that in-situ production of brGDGTs in shelf sediments is a widespread phenomenon that is especially pronounced at water depths of ca. 50–300 m. It is hypothesized that this is so because benthic in-situ production of heterotrophic brGDGT-producing bacteria is fueled by the higher delivery of fresh organic matter to these sediments as the consequence of higher primary productivity in shelf waters and a decreased mineralization due to the relatively short settling times of particles on the shelf. For palaeoclimatic studies of marine shelf sediments the application of brGDGTs as proxies is severely complicated by the heterogeneity of sources of brGDGTs. Comparison of the brGDGT composition of soils with those of shelf sediments may assist in deciding if sedimentary brGDGTs are predominantly derived from soil erosion. Several methods to do so are discussed

Sustainable Habitat Restoration: Fish, Farms, and Ecosystem Services

Biomass burning impacts biogeochemical cycling, vegetation dynamics and climate. However, interactions between fire, climate and vegetation are not well understood and therefore studies have attempted to reconstruct fire and vegetation history under different climatic conditions using sedimentary archives. Here we focus on levoglucosan, a thermal by-product of cellulose generated during biomass burning, and, therefore, a potential fire biomarker in the marine sedimentary archive. However, before levoglucosan can be applied as a biomass burning proxy in marine sediments, there is a need for studies on how levoglucosan is transported to the marine environment, how it is reflecting biomass burning on continents, as well as the fate of levoglucosan in the marine water column and during deposition in marine sediments. Here we present analyses of levoglucosan, using an improved Ultra High Pressure Liquid Chromatography-Electro Spray Ionization/High Resolution Mass Spectrometry (UHPLC-ESI/HRMS) method, in atmospheric particles, in particulate matter settling through the water column and in marine surface sediments on a longitudinal transect crossing the tropical North Atlantic Ocean at 12°N. Levoglucosan was detected in the atmosphere, although in low concentration, possibly due to the sampled particle size, the source area of the aerosols, or the short time interval of sampling by which large burning events may have been missed. In sinking particles in the tropical North Atlantic Ocean we find that levoglucosan deposition is influenced by a mineral ballast effect associated with marine biogenic particles, and that levoglucosan is not transported in association with mineral dust particles. Highest levoglucosan concentrations and seasonal differences in sinking particles were found close to continents and low concentrations and seasonal differences were found in the open ocean. Close to Africa, levoglucosan concentration is higher during winter, reflecting seasonal burning in northwestern Africa. However, close to South America levoglucosan concentrations appear to be affected by riverine transport from the Amazon River. In surface sediments close to South America, levoglucosan concentration is higher than in the middle of the Atlantic Ocean, implying that here the influence from the South American continent is important and perennial. Our study provides evidence that degradation of levoglucosan during settling in the marine water column is not substantial, but is substantial at the sediment–water interface. Nevertheless, levoglucosan was detected in all surface sediments throughout the tropical North Atlantic, indicating its presence in the marine sedimentary record, which reveals the potential for levoglucosan as a biomass burning proxy in marine sediments

Questions in Luke 1:5-2:52:Their Function in the Communication between the Text-internal Author and the Text-internal Reader

My dissertation studies the questions that are found in Luke 1:5–2:52. It does so in order to find out how they function in the communication between the author and the reader of the text.To analyse the text, I employ the Communication-Oriented Method. This method makes two assumptions. Firstly, it holds that the syntax of the text forms the basic structure in which all communication takes place. This means that the ‘grammar’ of the text is first scrutinised before the meaning of words and the communication itself are investigated. Secondly, this method makes a strict distinction between the text-external (or historical) author/reader, and the text-internal author/reader. The text-internal author/reader are textual constructs and, therefore, found only within the text. In my dissertation I focus only on the communication between the text-internal author and the text-internal reader. In other words, I only analyse the communication within the text, leaving the historical author/reader to other fields of research. Regarding the text-internal communication, the text-internal author can communicate with the text-internal reader directly, or indirectly (via the characters in the narrative).After having first determined the basic structure of the text, I go on to identify the questions that are found in the text. Questions can usually be identified by words such as ‘why’, ‘what’, and ‘how’. Sometimes, the meaning of the text points at questions that are not explicitly mentioned in the text.I then make a communication analysis of the text, focussing on the identified questions. My analysis leads me to the following conclusions. In the communication with the text-internal reader, the text-internal author uses questions to focus this reader’s attention on the character John, to stimulate the reader to identify with the character Mary, to emphasise the relation between the character Jesus and the temple in Jerusalem, and to prepare this reader for further misunderstandings regarding Jesus’ identity in the narrative to come.Generally, the questions found in Luke 1:5–2:52 function at the level of the characters as a communication ‘motor’, with the goal of promoting, prolonging, and intensifying the communication between the characters. At the level of the text-internal author/reader, the questions in Luke 1:5–2:52 function as a narrative ‘motor’, driving the text-internal author’s narrative by setting further action and communication in motion._Mijn dissertatie onderzoekt de vragen die in Lucas 1:5–2:52 voorkomen om te ontdekken hoe zij functioneren in de communicatie tussen auteur en lezer.Om de tekst te analyseren gebruik ik de Communication-Oriented Method. Deze methode heeft twee uitgangspunten. Ten eerste: de basisstructuur waarbinnen alle communicatie plaatsvindt, wordt gevormd door de syntaxis van de tekst. Dit betekent dat de ‘grammatica’ van de tekst eerst bestudeerd wordt, voordat de betekenis van de woorden en de communicatie zelf worden onderzocht. Ten tweede: deze methode maakt een strikt onderscheid tussen de tekst-externe (of historische) auteur/lezer en de tekst-interne auteur/lezer. De tekst-interne auteur/lezer zijn tekstuele constructen en worden dus alleen binnen de tekst aangetroffen. In mijn dissertatie focus ik uitsluitend op de communicatie tussen de tekst-interne auteur en de tekst-interne lezer. Met andere woorden: ik analyseer alleen de communicatie binnen de tekst, en laat de historische auteur/lezer over aan andere onderzoeksvelden. Wat de tekst-interne communicatie betreft, kan de tekst-interne auteur ofwel direct ofwel indirect (via de characters in het verhaal) communiceren met de tekst-interne lezer.Nadat ik eerst de basisstructuur van de tekst heb vastgesteld, identificeer ik vervolgens de vragen die in de tekst voorkomen. Vragen kunnen meestal geïdentificeerd worden aan de hand van woorden zoals ‘waarom’, ‘wat’ en ‘hoe’. Soms verwijst de betekenis van de tekst naar vragen die niet expliciet verwoord worden in de tekst.Daarna maak ik een communicatieve analyse van de tekst, toegespitst op de door mij geïdentificeerde vragen. Mijn analyse biedt mij de volgende conclusies. In de communicatie met de tekst-interne lezer maakt de tekst-interne auteur gebruik van vragen om de aandacht van deze lezer te focussen op het character Johannes, om de lezer te stimuleren zich te identificeren met het character Maria, om de relatie tussen het character Jezus en de tempel in Jeruzalem te benadrukken, en om deze lezer voor te bereiden op verdere miscommunicaties ten aanzien van de identiteit van Jezus in het verdere verhaal.Over het algemeen functioneren de vragen in Lucas 1:5–2:52 op het niveau van de characters als een communicatieve ‘motor’, met als doel de communicatie tussen de characters onderling te bevorderen, te verlengen en te intensiveren. Op het niveau van de tekst-interne auteur/lezer, functioneren de vragen in Lucas 1:5–2:52 als een narratieve ‘motor’, die het verhaal van de tekst-interne auteur aandrijft door verdere actie en communicatie in gang te zetten

Latitudinal differences in the amplitude of the OAE-2 carbon isotopic excursion: pCO2 and paleoproductivity [Discussion paper]

A complete, well-preserved record of the Cenomanian/Turonian (C/T) Oceanic Anoxic Event 2 (OAE-2) was recovered from Demerara Rise in the southern North Atlantic Ocean (ODP site 1260). Across this interval, we determined changes in the stable carbon isotopic composition of sulfur-bound phytane (δ13Cphytane, a biomarker for photosynthetic algae. The δ13Cphytane record shows a positive excursion at the onset of the OAE-2 interval, with an unusually large amplitude (~7 ‰) compared to existing C/T proto-North Atlantic δ13Cphytane records (3–6 ‰). Overall, the amplitude of the excursion of δ13Cphytane decreases with latitude. Using reconstructed sea surface temperature (SST) gradients for the proto-North Atlantic, we investigated environmental factors influencing the latitudinal δ13Cphytane gradient. The observed gradient is best explained by high productivity at DSDP Site 367 and Tarfaya basin before OAE-2, which changed in overall high productivity throughout the proto-North Atlantic during OAE-2. During OAE-2, productivity at site 1260 and 603B was thus more comparable to the mid-latitude sites. Using these constraints as well as the SST and δ13Cphytane-records from Site 1260, we subsequently reconstructed pCO2 levels across the OAE-2 interval. Accordingly, pCO2 decreased from ca. 1750 to 900 ppm during OAE-2, consistent with enhanced organic matter burial resulting in lowering pCO2. Whereas the onset of OAE-2 coincided with increased pCO2, in line with a volcanic trigger for this event, the observed cooling within OAE-2 probably resulted from CO2 sequestration in black shales outcompeting CO2 input into the atmosphere. Together these results show that the ice-free Cretaceous world was sensitive to changes in pCO2 related to perturbations of the global carbon cycle

Latitudinal differences in the amplitude of the OAE-2 carbon isotopic excursion : pCO2 and paleo productivity

A complete, well-preserved record of the Cenomanian/Turonian (C/T) Oceanic Anoxic Event 2 (OAE-2) was recovered from Demerara Rise in the southern North Atlantic Ocean (ODP site 1260). Across this interval, we determined changes in the stable carbon isotopic composition of sulfur-bound phytane (δ13Cphytane), a biomarker for photosynthetic algae. The δ13Cphytane record shows a positive excursion at the onset of the OAE-2 interval, with an unusually large amplitude (~7‰) compared to existing C/T proto-North Atlantic δ13Cphytane records (3–6‰). Overall, the amplitude of the excursion of δ13Cphytane decreases with latitude. Using reconstructed sea surface temperature (SST) gradients for the proto-North Atlantic, we investigated environmental factors influencing the latitudinal δ13Cphytane gradient. The observed gradient is best explained by high productivity at DSDP Site 367 and Tarfaya basin before OAE-2, which changed in overall high productivity throughout the proto-North Atlantic during OAE-2. During OAE-2, productivity at site 1260 and 603B was thus more comparable to the mid-latitude sites. Using these constraints as well as the SST and δ13Cphytane-records from Site 1260, we subsequently reconstructed pCO2 levels across the OAE-2 interval. Accordingly, pCO2 decreased from ca. 1750 to 900 ppm during OAE-2, consistent with enhanced organic matter burial resulting in lowering pCO2. Whereas the onset of OAE-2 coincided with increased pCO2, in line with a volcanic trigger for this event, the observed cooling within OAE-2 probably resulted from CO2 sequestration in black shales outcompeting CO2 input into the atmosphere. Together these results show that the ice-free Cretaceous world was sensitive to changes in pCO2 related to perturbations of the global carbon cycle