The different shades on the left$-$hand graph are for lipids, amino acids, sugars, and uncharacterized in particulate organic carbon $($POC$).$ Draw a similar plot for DOC on the axes on the left. On the $y$ axes, use three depths to indicate where water was sampled with a CTD: $1$ at the surface $(1m),1$ at intermediate depth $(500m)$ and $1$ at depth $(2000m).$ The $x-$axis should be the same as for the POC plot $($Percent of DOC from $0-100).(3)$

What is one trend that is similar in the DOC plot that you just drew and the POC plot on the left? Why do we see this trend? $(1)$