What is the applications of carbon isotopes?

Answer 1

The main ones are using c14. Radiocarbon dating gives acurate dating of historic and prehistoric organic materials. Also, c14 is used to "tag" carbon compounds to track how different sources of carbon are used in molecular Biology/biochemistry.

Additionally, c3 and c4 plants (this difference is in the regulation of photosynthesis) take in carbon isotopes at different rates. A c4 plant (like corn) will use c13 as readily as c12. However, c3 plants will not use c13 as readily as c12. This means that the ratio of c12 to c13 is different in c3 plants then in c4 plants. More importantly, the ratios are kept through tropic levels: when an animal uses carbon from a c4 plant, the ratio of c12 to c13 will be the same as in the plant. The use: we (humans in general) can analyze the ratio of c12 to c13 in animals, showing if they consume mostly c3 or c4 plants. This means that we can track carbon through a food chain or see if an historic tribe consumed more land based food (more likely c4) or sea food (completely c3). The studies that show that people from the US are 90% corn? Corn is the most common c4 food/carbon source today, and this type of study finds that people in the US have a c12 to c13 ratio that corresponds to 90% of our food to be derived from c4 plants.