How have scientists used isotopic analysis to determine the rise of atmospheric CO₂ is mostly from the burning of fossil fuels?
A) Since ¹⁴C is an unstable isotope, scientists have dated the atmospheric carbon to the period since the Industrial Revolution.
B) Both coal and oil contain a high proportion of ¹⁴C. By analyzing, ¹⁴C/¹²C ratios, scientists have been able to determine the source based on this fact.
C) The low proportions of ¹³C and ¹⁴C within atmospheric CO₂ indicates the source is fossil carbon.
D) ¹⁴C concentrations are much higher in urban areas than in rural areas, indicating fossil fuels must have a higher ¹⁴C/¹²C ratio than carbon from other sources.

Question

Quizplus · Accepted Answer

Fossil fuels are depleted in ¹³C and ¹⁴C because they are ancient and have lost these isotopes over time. The low proportions of these isotopes in atmospheric CO₂ indicate that the carbon is from fossil sources.

How Have Scientists Used Isotopic Analysis to Determine the Rise