Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

Treatment description and growth parameters for Thalassiosira weissflogii generating d13C-AA.

Temperature and irradiance values are means of outdoor conditions; the 25% and 75% quartiles for temperature were 9.8 and 11.3 deg C, and the 25% and 75% quartiles for irradiance levels were 269 and 1274 umol m-2 s-1.

These data were published in:

Larsen T, , L. T. Bach, R. Salvatteci, M. Ventura, Y. V. Wang, N. Andersen, and M. D. McCarthy (2015).  Assessing the potential of amino acid d13C patterns as a carbon source tracer in marine sediments: effects of algal growth conditions and sedimentary diagenesis. (Biogeosciences, 12, 4979-4992. doi:10.5194/bg-12-4979-2015

Culturing

The marine diatom Thalassiosira weissflogii Grunow (strain CCMP 1010) was cultured in sterile filtered natural North Sea water (Schleswig-Holstein, Germany) or Baltic Sea water (Schleswig-Holstein, Germany). The medium was enriched with f/4 concentrations of macro- and micronutrients (nitrate, phosphate, silicic acid, trace metal mixture, vitamin mixture (Guillard and Ryther, 1962). All experiments were performed in sterile 2.1 L Schott Duran glass bottles. These bottles were made of borosilicate glass (filters UV radiation <310 nm) except for the quartz glass bottles (pure silica without UV radiation filter) used in the UV experiment. The cultures were either incubated in climate chambers with 400 –700 nm radiation or 10 cm below water level at low tide in Kiel Fjord in May 2011. Water temperature and light irradiance data were obtained from the weather station maintained by the GEOMAR institute in Kiel, Germany. Growth conditions for the various treatments, i.e. salinity, pH, temperature, and irradiance are given in Table 1. pH values (reported on free scale) were measured  with separate glass and reference electrodes (Metrohm) and calculated with equation 3 from DOE 2007 chapter 6b (Dickson et al., 2007) as described in (Bach et al., 2012). Cultures were inoculated with densities of 20 cells ml-1.  Cell densities and equivalent spherical diameters were determined with a Coulter Counter (Beckman Coulter) at the beginning and the end of the experiment, respectively. When incubations ended, cells were filtered on 47 mm diameter, 5 um mesh size Nucleopore Track-Etch Membrane filters (Whatman) and frozen at -18 deg C immediately after filtration.

Thermo-Finnigan Isodat software and Microsoft Excel 2013.

BCO-DMO Processing:

- changed column names to comply with BCO-DMO standards
- captured superscript numbers by changing them to (1) and (2) where appropriate
- changed degree symbol to "deg"
- deleted blank columns
- combined pH headers to create pH columns pH_init and pH_term

The bioavailability of nutrients plays a crucial role in oceanic biological productivity, the carbon cycle, and climate change. The global ocean inventory of nitrogen (N) is determined by the balance of N-fixation (sources) and denitrification (sinks). In this three-year project, a researcher from the University of California, Santa Cruz, will focus on developing compound-specific N isotope (d15N) analysis of amino acids as a new tool for understanding N source and transformation of organic matter in paleo-reservoirs. The offsets in the isotopic ratios of individual amino acid groups may yield information about trophic transfer, heterotrophic microbial reworking, and autotrophic versus heterotrophic sources. By measuring and comparing the bulk and amino acid d15N in size-fractioned samples from plankton tows, sediments traps, and multi-cores in oxic and suboxic depositional environments, the researcher will: (1) Provide a proxy of the d15N of average exported photoautotrophic organic matter; and (2) Provide a new level of detail into sedimentary organic N degradation and preservation.

Broader impacts:
This project will improve understanding of the fundamental underpinnings and behaviors of d15N amino acid patterns and how they behave in contrasting sedimentary environments, while also developing a potential paleoceanographic proxy. Funding will support a graduate student and undergraduate research at the institution. The researcher will also conduct community outreach in the form of a workshop/tutorial on the proxy development.