Biogenic silica analyses
Biogenic silica content (BSi, diatom remains) of sediment is a useful climate proxy that can be analyzed rapidly at high resolution. For example, McKay et al. (2008) found that BSi in lake sediment from south-central Alaska was correlated with summer air temperature, and used this relation to quantitatively reconstruct temperature over the last 2000 years. The Sediment Lab analyzes the BSi content of lake and marine sediment collected by collaborating scientists. BSi is extracted from ~100 mg of sediment with 10% Na2CO3 and the concentration is determined with molybdate-blue recution and spectrophotometry following the procedure of Mortlock and Froelich (1989). The rate $25 per sample.
Particle size analyses
The particle size of sediment in lakes and other depositional settings is controlled by the prevailing environmental conditions of drainage basin, and by the dynamics of the sediment-transport and depositional systems. The particle-size distribution therefore is a fundamental characteristic of sediment that has been used widely to track environmental changes. Our procedure isolates the minerogenic component of the sediment from biogenic material, and uses a laser-diffraction particle-size analyzer (Coulter LS230) to measure the particle-size distribution. The particle-size distribution is determined by the relative proportion of grain sizes from 2 mm to 0.04 µm, the mean grain size, and the sorting. Contact the lab for pricing information.
Ostracode analyses
Ostracodes are small crustaceans that inhabit nearly all aquatic environments. Ostracodes secrete calcium carbonate bivalved shells that are frequently preserved in lake and marsh sediments. The laboratory has expertise in the taxonomy of freshwater ostracodes, and it a houses a reference collection of ostracode valves from the western US. The assemblage of ostracode species recovered from sediment is used to interpret several environmental parameters of the depositional setting, including water chemistry, permanence, and temperature. The standard rate is $150 per sample.
Isotope analyses
Laboratory personnel are experienced at preparing samples for isotope analyses, including purifying diatoms and isolating ostracodes for oxygen isotope analyses, and preparing samples for radiocarbon dating by AMS.
