Validation of carbon isotope fractionation in algal lipids as a &amp;lt;i&amp;gt;p&amp;lt;/i&amp;gt;CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; proxy using a natural CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; seep (Shikine Island, Japan)
Biogeosciences