AMS radiocarbon dating is widely used method to determine the age of organic materials, including geological soil and bottom sediments. We can prepare and analyze humin or bulk fraction, or both fractions. Soil sample’s recommended quantity is 1 grams. Prior to radiocarbon (14C) dating all samples are being selected and pre-treated according to the type, quantity and condition of material, and then graphitized. This is one of the most important phases in the carbon dating process, which requires highest expertise to achieve reliable and accurate result. Soil and sediment samples in VILNIUS RADIOCARBON laboratory are being pre-treated using exceptionally best-on-the-market chemicals and consumables and strictly following internally and internationally approved methodology according to the protocol.
Preferred sample size: 1 g
Minimum sample size: 200 mg
Sediment refers to particles of organic and inorganic matter that accumulate over time and settle at the bottom of bodies of water, such as rivers, lakes, oceans, or other liquid environments. Sediments can include materials like sand, silt, clay, and decaying organic matter. Sediment samples can be dated using several fractions: macrofossils, bulk fraction, humin, and humic acid.
Sediments can contain macrofossils - preserved remains (e.g., charcoal, plant, shell), which can be visible. Macrofossils yield the most accurate radiocarbon dates when they are part of the sediment formation. However, distinguishing between original deposition and younger intrusive materials (e.g., rootlets, insect parts, seed caches) can be challenging. Charcoal, among various macrofossil types, is preferred due to its distinctiveness, reducing the likelihood of confusion with younger materials.
When macrofossils are not available, bulk carbon dating becomes the predominant method. Bulk carbon dating is best suited for sediments that are well-buried, capped, undisturbed (e.g., peaty sediment), and have lower carbon content. Chemical preparation involves acid treatment (1M HCl) (70°C). of the sample and drying in pH=3 solution.
Preferring to date the humin or humic acid fraction may be advantageous in certain situations, but specific site variables make it challenging to provide universal guidelines. In this case samples are treated using the standard acid-base-acid (ABA) method. The samples are treated with a sequence of 1M HCl (70°C), distilled water, 0.1M NaOH (70°C), distilled water (until the solution is colorless), and then 1M HCl (70°C). To obtain the base-soluble fraction the discarded base washes are retained and acidified so that humic acid precipitates fall out, which are then washed with water and dried.
Before sending the sample, we recommend to check here, how your sample’s result in the dating certificate will look.