Abstract. In this comment, we outline two major concerns regarding some of the key data
presented in this paper. Both of these concerns are associated with the
natural abundance radiocarbon-methane (14C-CH4) data. First, no systematic methodology
is presented, nor previous peer-reviewed publication referenced, for how
these samples were collected, prepared, and ultimately analyzed for
14C-CH4. Not only are these procedural details missing, but
the critical evaluation of them using gaseous and aqueous blanks and
standards was omitted although these details are essential for any reader to
evaluate the quality of data and subsequent interpretations. Second, due to
the lack of methodological details, the source of the sporadic anthropogenic
contamination cannot be determined and thus it is premature for the authors
to suggest it was in the natural environment prior to sample collection. As
the natural 14C-CH4 data are necessary for the authors'
stated scientific objectives of understanding the origin of methane in the
East Siberian Arctic Shelf, our comment serves to highlight that the study's
objectives have not been met.
Comment on “The origin of methane in the East Siberian Arctic Shelf unraveled with triple isotope analysis” by Sapart et al. (2017)