Marine radionuclides (natural vs. man-made)

　Finally, we compare natural and artificial radionuclides. In the figure below, natural radionuclides are light brown and artificial radionuclides are pink.

Since tritium (³H) and carbon 14 (¹⁴C) have sources from both sources, they were calculated separately.

After all, you can see that the abundance of natural radionuclides is overwhelming. However, tritium (³H) seems to be more artificial. This is because artificial radionuclides released by atmospheric nuclear testing remain. Estimates are for the year 2000 AD, so in 2020 we can calculate that the ratio of natural and artificial will be about half and half. As I mentioned about tritium, tritium (³H) is also produced from nuclear power plants, but it is characterized by the overwhelming amount produced by cosmic rays. As for carbon 14 (¹⁴C), the ratio of man-made to natural is about 1%, so if it is used for dating, the error is only a small amount.

天然VS人口natural vs population　天然放射性核種natural radionuclides　人工放射性核種artificial radionuclides　圧倒的にK40が多いThere are overwhelmingly many K40

　A comparison like this might lead to the argument that "natural radionuclides are overwhelmingly abundant, so artificial radionuclides are not a problem," but that is not necessarily the case. As long as the radionuclides are evenly dispersed in the seawater of the ocean, it seems that there is no problem whether it is natural or artificial. However, radionuclides are dangerous when they are concentrated in a certain place at a certain time. It is important to judge this area carefully.