methods & facilities
bulk isotope analysis
Bulk stable isotope analysis is a method to analyze the isotopic composition of a variety of substrates such as minerals or organic matter. We primarily analyze isotopes of carbon (13C/12C, 14C/12C), nitrogen (15N/14N) and sulfur (34S/32S) to infer past and present redox conditions, metabolic rates, or the source and origin of organic matter in marine sediments.
We use isotope ratio mass spectrometry (IRMS) to obtain these data, i.e., burning samples in a high temperature oven (an elemental analyzer), purifying the resulting gases and inserting them into the IRMS to separate light and heavy isotopes. In some instances, we purify different chemical fractions to determine the isotopic differences.
want more details? check out our publications! here are two examples:
Liu J, Antler G, Pellerin A, Izon G, Dohrmann I, Findlay AJ, Røy H, Ono S, Turchyn AV, Kasten S & Jørgensen BB (2021) Isotopically “heavy” pyrite in marine sediments due to high sedimentation rates and non-steady-state deposition. Geology 49, 816-821. doi: 10.1130/g48415.1.
Riemer S, Turchyn A, Pellerin A & Antler G (2023) Digging deeper: Bioturbation increases the preserved sulfur isotope fractionation. Frontiers in Marine Science 9, 1039193. doi: 10.3389/fmars.2022.1039193.
compound-specific stable isotope analysis
Compound-specific isotope analysis (CSIA) is a technique used to determine the isotopic composition of organic molecules. Most commonly, the hydrogen (2H/1H) and/or carbon (13C/12C) isotopic composition is analyzed to infer the water source and substrate utilized by organisms. Based on these data, we can – for example – infer precipitation dynamics or the metabolism of an organism. If molecules contain nitrogen functionalities, we can also analyze the nitrogen (15N/14N) isotopic composition. We obtain our data using gas chromatography-isotope ratio mass spectrometry (GC-IRMS).
want more details? check out our publications! here are two examples:
Elling FJ, Gottschalk J, Doeana KD, Kusch S, Hurley SJ & Pearson A (2019) Archaeal lipid biomarker constraints on the Paleocene-Eocene carbon isotope excursion. Nature Communications 10: 4519. doi: 10.1038/s41467-019-12553-3.
Hemingway JD, Kusch S, Shah Walter SR, Polik CA, Elling FJ & Pearson A (2018) A novel method to measure the 13C composition of intact bacteriohopanepolyols. Organic Geochemistry 123, 144-147. doi: 10.1016/j.orggeochem.2018.07.002.
compound-specific radiocarbon analysis
Compound-specific radiocarbon analysis (CSRA) is a dedicated technique to study the radioactive carbon isotopic composition (14C/12C) of organic molecules. It is a powerful tool to provide fundamental information about biogeochemical processes in the ocean, determine metabolic pathways, and to date marine sediments in the absence of carbonate microfossils. We use preparative gas chromatography (PCGC) or liquid chromatography (LC) to isolate our samples for accelerator mass spectrometry (AMS) analysis.
want more details? check out our publications! here are two examples:
Kusch S, Mollenhauer G, Willmes C, Hefter J, Eglinton TI & Galy V (2021) Controls on the age of plant waxes in marine sediments – a global synthesis (invited review article). Organic Geochemistry 157, 104259. doi: 10.1016/j.orggeochem.2021.104259.
Mollenhauer G, Kusch S, Eglinton TI & Pearson A (2019) Compound-specific Radiocarbon Measurements. Encyclopedia of Ocean Sciences – Reference Module in Earth Systems and Environmental Sciences, Third Edition. Eds Cochran JK, Bokuniewicz H & Yager P. Academic Press. Vol 1, 235-244. doi: 10.1016/B978-0-12-409548-9.11432-0.
biomarker analysis
Biomarkers are molecules that have known source organisms. At least, biomarkers are characteristic for archaea, bacteria, or eukaryota (the three kingdoms of life on Earth). At best, they are chemotaxonomically specific (meaning, they are synthesized by certain species only). Lipid biomarkers preserve well in the geological record and although they can be chemically altered through time, they retain characteristic molecular structures. We can – for example – infer metabolisms and community composition in the ocean through time or reconstruct ocean paleotemperatures. To obtain biomarker data, we use gas chromatography-mass spectrometry (GC-MS) and liquid chromato-graphy-mass spectrometry (LC-Orbitrap).
want more details? check out our publications! here are two examples:
Kusch S, Wakeham SG & Sepúlveda J (2022) Bacteriohopanepolyols across the Black Sea redoxcline trace diverse bacterial metabolisms. Organic Geochemistry 172, 104462. doi: 10.1016/j.orggeochem.2022.104462.
Steinig S, Dummann W, Park W, Latif M, Kusch S, Hofmann P & Flögel S (2020) Evidence for a regional warm bias in the Early Cretaceous TEX86 record. Earth and Planetary Science Letters 539, 116184. doi: 10.1016/j.epsl.2020.116184.
porewater chemistry
Porewater fills the porous space between the grains in marine or lacustrine sediments. It is a conduit from the water column to the sediments and contains valuable information. For example, the amount dissolved inorganic carbon is a function of how much organic carbon is being consumed in the sediment. To extract porewater from sediments, we mostly use rhizons (filter sticks that can be inserted into the sediment and “suck” the water out by applying a vacuum). Porewaters are recovered and preserved for analysis in the laboratory.
want more details? check out our publications! here are two examples:
Pellerin A, Antler G, Røy H, Findlay A, Beulig F, Scholze C, Turchyn AV & Jørgensen BB (2018) The sulfur cycle below the sulfate-methane transition of marine sediments. Geochimica Et Cosmochimica Acta 239, 74-89. doi: 10.1016/j.gca.2018.07.027.
Liu J, Pellerin A, Antler G, Kasten S, Findlay AJ, Dohrmann I, Røy H, Turchyn AV & Jørgensen BB (2020) Early diagenesis of iron and sulfur in Bornholm Basin sediments: The role of near-surface pyrite formation. Geochimica et Cosmochimica Acta 284, 43-60. doi: 10.1016/j.gca.2020.06.003.
environmental gases
Monitoring the concentrations of gases in seawater and air is an important part of marine sciences and climate change research. It is also essential for monitoring microbial processes in agricultural soils or in rapidly changing ecosystems such as in permafrost. We use gas chromatography (GC) with flame ionization detection (FID) and electron capture detection (ECD) to measure gases found at low concentrations such as methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O). With the ECD, it is also possible to analyze halogenated gases/ compounds.
want more details? check out our publications! here is an example:
Pellerin A, Lotem N, Walter Anthony K, Eliani Russak E, Hasson N, Røy H, Chanton JP & Sivan O (2022) Methane production controls in a young thermokarst lake formed by abrupt permafrost thaw. Global Change Biology 28, 3206-3221. doi: 10.1111/gcb.16151.
acid distillation
Acid distillation is a method to separate different fractions of sulfur species from environmental samples. We expose the samples to different strong acids under a stream of N2 gas. The acid reacts with the sulfur compounds and produces H2S gas, which is carried by the N2 stream and recovered in a trap after removal of the acids.
want more details? check out our publications! here are two examples:
Liu J, Pellerin A, Antler G, Izon G, Findlay AJ, Røy H, Ono S, Kasten S, Turchyn AV & Jørgensen BB (2021) Early diagenesis of sulfur in Bornholm Basin sediments: The role of upward diffusion of isotopically “heavy” sulfide. Geochimica et Cosmochimica Acta 313, 359-377. doi: 10.1016/j.gca.2021.08.018.
Magnuson E, Mykytczuk NCS, Pellerin A, Goordial J, Twine SM, Wing B, Foote SJ, Fulton K & Whyte L G (2020) Thiomicrorhabdus streamers and sulfur cycling in perennial hypersaline cold springs in the Canadian high Arctic. Environmental Microbiology, 23, 3384-3400. doi: 10.1111/1462-2920.14916.
elemental analysis
Elemental analysis is an essential part of the data we collect for our research. We are primarily interested in the concentrations of carbon, nitrogen and sulfur in marine and lacustrine sediments. These are used to understand the conditions under which the sediments were deposited as well as to normalize biomarker data. The analyses are automated using an elemental analyzer which burns small samples at high temperature, purifies the resulting gases and measures the gas signal with a thermal conductivity detector.
want more details? check out our publications! elemental data are included in nearly all of them.
ISMER_Isotope Biogeochemistry 