Scientists say the excess heavy nitrogen could have come from a comet. And the heavier oxygen from a natural process that left more of the light isotope in the part of the nebula that made the sun.
And the heavier oxygen from a natural process that left more of the light isotope in the part of the nebula that made the sun.
重量较大的氧来自某种自然过程，在此过程中，大部分的轻同位素留在了形成太阳的部分星云中。
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This approach underpins much of my research on energy and nutrient flux, and has involved both natural abundance and enriched isotope tracing techniques.