You are welcome to contact us to discuss the pretreatment or request that we contact you after the pretreatment to discuss options for radiocarbon dating. However, knowing the dry weight will better allow you to estimate the amount of material to send.If you want to dry your samples, heating at 90°C to 100°C for 4-24 hours is recommended.– If the macrofossils are chosen for the analysis, the reported results will be as “plant material”.If the sediment is chosen for the analysis, the reported results will be as “bulk organic carbon” or “total acid insoluble organics” depending on the sediment fractions included in the analysis.For sediment samples, the lab performs flotation in water then progressive sieving through 225-micron, 180-micron, and then 125-micron sieves to see if there are any macrofossils that can be extracted.Examples of these macrofossils include charcoal, wood, plant, bone, shell, and seeds.
HA1 is the first fraction extracted by 30 minutes' heating with 2 percent Na OH solution, and HA2 is the second fraction extracted by 2 hours' heating with 2 percent Na OH solution after the extraction of HA1. Many of the peat or soil samples taken from the layer just above the nonpermeable layer contain appreciable amounts of organic materials transported from the upper layer after the sedimentation of the deposits.
Note: Our lab does not identify the exact type of macrofossil found in the sediment.
Identification of macrofossils requires highly trained scientists, e.g.
Most macrofossils can be treated with (1) acid to remove carbonates, and (2) alkali to remove humic acids that might be in the sediment. Sediment and rain water or ground water can move these humic acids up or down through the sedimentary profile bringing carbon that is either younger or older into a sediment layer.
In most cases, humic acids travel downward and make the underlying sediment appear to be younger (sometimes by a small amount, sometimes by a large amount of bias).