Articles by Barbara M.A. Teichert in JoVE
Preparation of Authigenic Pyrite from Methane-bearing Sediments for In Situ Sulfur Isotope Analysis Using SIMS Zhiyong Lin1,3, Xiaoming Sun1,2,3,4, Jörn Peckmann5, Yang Lu2,3, Harald Strauss6, Li Xu2,3, Hongfeng Lu7, Barbara M.A. Teichert6 1School of Earth Sciences and Engineering, Sun Yat-sen University, 2School of Marine Sciences, Sun Yat-sen University, 3Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, 4South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, 5Institut für Geologie, Universität Hamburg, 6Institut für Geologie und Paläontologie, Westfälische Wilhelms-Universität Münster, 7Guangzhou Marine Geological Survey Analyses of the sulfur isotopic composition (δ34S) of pyrite from methane-bearing sediments have typically focused on bulk samples. Here, we applied secondary ion mass spectroscopy to analyze the δ34S values of various pyrite generations to understand the diagenetic history of pyritization.
Other articles by Barbara M.A. Teichert on PubMed
Sulphur Diagenesis in the Sediments of the Kiel Bight, SW Baltic Sea, As Reflected by Multiple Stable Sulphur Isotopes Isotopes in Environmental and Health Studies. 2012 | Pubmed ID: 22303924 In this work, the biogeochemistry of marine sediments from the Kiel Bight, coastal SW Baltic Sea, is studied based on the abundance and isotopic composition of organic carbon and different forms of sedimentary sulphur. Active bacterial sulphate reduction, partly under sulphate-limiting conditions, is evident from paired δ(34)S and δ(18)O values of pore water sulphate. The resulting pore water sulphide is partly precipitated as acid-volatile iron sulphide and subsequently forms sedimentary pyrite, partly serves in later diagenetic sulphurisation of organic matter, or remains dissolved in the pore water, all evident from the respective δ(34)S values. Microbial sulphate turnover is associated with an apparent isotopic fractionation between dissolved sulphate and dissolved sulphide (Δ(34)S) that varies between 46 and 66‰.
Calcium-ammonium Exchange Experiments on Clay Minerals Using a (45)Ca Tracer Technique in Marine Pore Water Isotopes in Environmental and Health Studies. 2014 | Pubmed ID: 24437731 Understanding cation exchange processes is important for evaluating early diagenetic and synsedimentary processes taking place in marine sediments. To quantify calcium (Ca) exchange and Ca-ammonium exchange in a seawater environment, we performed experiments with a radioactive (45)Ca tracer on clay mineral standards (Fithian illite, montmorillonite and kaolinite) and marine sediments from the North Atlantic Integrated Ocean Drilling Program Site U1306A in artificial seawater (ASW). The results show that equilibrium during the initial attachment of Ca as well as the exchange of Ca by [Formula: see text] is attained in less than 2 min. On average 8-20% of the exchangeable sites of the clay minerals were occupied by Ca in a seawater medium. The conditional selectivity coefficient, describing the [Formula: see text] exchange in ASW is mineral specific and it was determined to be 0.07 for montmorillonite, 0.05 for a natural marine sediment and 0.013 for Fithian illite.
Multiple Sulphur and Oxygen Isotopes Reveal Microbial Sulphur Cycling in Spring Waters in the Lower Engadin, Switzerland Isotopes in Environmental and Health Studies. Mar-May, 2016 | Pubmed ID: 25922968 Highly mineralized springs in the Scuol-Tarasp area of the Lower Engadin and in the Albula Valley near Alvaneu, Switzerland, display distinct differences with respect to the source and fate of their dissolved sulphur species. High sulphate concentrations and positive sulphur (δ(34)S) and oxygen (δ(18)O) isotopic compositions argue for the subsurface dissolution of Mesozoic evaporitic sulphate. In contrast, low sulphate concentrations and less positive or even negative δ(34)S and δ(18)O values indicate a substantial contribution of sulphate sulphur from the oxidation of sulphides in the crystalline basement rocks or the Jurassic sedimentary cover rocks. Furthermore, multiple sulphur (δ(34)S, Δ(33)S) isotopes support the identification of microbial sulphate reduction and sulphide oxidation in the subsurface, the latter is also evident through the presence of thick aggregates of sulphide-oxidizing Thiothrix bacteria.