Dear Dr. Apache and co-authors, I'm pleased to accept your paper for publication. In reading through your revised manuscript I have a few very minor suggestions, and a couple of questions. The decision I've entered is to "publish subject to technical corrections", so you are entirely free to rely on your own judgement in deciding whether to take a suggestion or not.

It was a pleasure to see this paper through to acceptance.

yours, --Matthew Hecht

Here are some suggested changes — all very minor — along with a couple of questions.

lines 79-81:
2004) and to study ocean dynamics (circulation, ventilation and mixing processes) in conjunction with tritium (

might better lead into the sentence on ventilation if reworked as:

2004), and in conjunction with tritium has been used to study ocean circulation, ventilation and mixing processes (

line 125: from 11°W to 7.5° -> from 11°W to 7.5°W

line 251: 1987 Meteor section -> The 1987 Meteor section

line 254: which allows to derive -> which allows one to derive

line 261: to the measured delta^3 He -> from the measured delta^3 He

line 342: to too-negative -> to excessively negative

line 419: pressure it is -> pressure that it is

line 824: is “idem” a typo?

On the two points that follow, from the figure captions, I may be misunderstanding as someone who is clearly outside of my area of expertise. Perhaps you could send me an email to explain (to mhecht@lanl.gov), so that I will have learned more from the process of overseeing the review of your paper!

Fig 1: “Most of the crustal helium consists of 4He, and most of the mantle helium consists of 3He”. Is this stated correctly? Isn’t there always far more 4He than 3He both in crust and mantle, and then it’s only a matter of whether the small fraction of He that is 3He is enhanced or depleted, relative to the composition of air?

Fig 6: if this is vertically integrated, then are the units meters (or equivalently delta^3(He)*meters)? Why do you show it as a vertically integrated quantity rather than vertically averaged?