P.075 Chronic hepatitis B (CHB) management costs in Sweden

Abstract

<dm:abstracts xmlns:dm="http://www.elsevier.com/xml/dm/dtd"><ce:abstract xmlns:ce="http://www.elsevier.com/xml/common/dtd" class="author" xml:lang="en" id="ab005" view="all"><ce:section-title id="st005">Abstract</ce:section-title><ce:abstract-sec id="as005" view="all"><ce:simple-para id="sp0005" view="all"><ce:cross-ref refid="b0060" id="c0020">Miller et al. (2016)</ce:cross-ref> report a new study of fluids in the peridotites of the Samail ophiolite in Oman related to modern serpentinization (olivine hydration), a process that can provide energy and raw materials for chemosynthetic microbial life. The authors, in particular, report an isotopic composition for methane (CH<ce:inf loc="post">4</ce:inf>) in groundwater near Ibra (up to 1.4 mM) that is unusually <ce:sup loc="post">13</ce:sup>C-enriched (δ<ce:sup loc="post">13</ce:sup>C<ce:inf loc="post">CH4</ce:inf> ∼ +2.4 and +3 ‰ VPDB), and consider the gas origin to be uncertain, i.e., abiotic or microbial, and to be modulated by significant fractionation due to oxidation or diffusion. The purpose of this comment is to clarify and correct a few points concerning the possible origin of the δ<ce:sup loc="post">13</ce:sup>C<ce:inf loc="post">CH4</ce:inf> values, with the intention to promote a fruitful and constructive debate, considering the interest that there is for serpentinization and the associated formation of various gases.</ce:simple-para><ce:simple-para id="sp0010" view="all">The CH<ce:inf loc="post">4</ce:inf> data from Miller et al. are re-examined in a global context of gas in serpentinized peridotites and, in particular, by considering published data (isotope composition of CH<ce:inf loc="post">4</ce:inf> and concentrations of C<ce:inf loc="post">2+</ce:inf> alkanes) also obtained from the Samail ophiolite, data neglected by the authors. These data significantly impact the interpretation of Miller et al. concerning the possibility that methane can be microbial. Potential isotopic fractionations by oxidation or diffusion, evaluated considering δ<ce:sup loc="post">13</ce:sup>C<ce:inf loc="post">CH4</ce:inf>–δ<ce:sup loc="post">2</ce:sup>H<ce:inf loc="post">CH4</ce:inf> correlated variations, the occurrence of significant amounts of ethane and propane in the Oman ophiolite aquifers and Rayleigh fractionation analysis suggest that methane can hardly be considered microbial. Isotopic fractionations, however, are not necessary to explain the unusual δ<ce:sup loc="post">13</ce:sup>C<ce:inf loc="post">CH4</ce:inf> values: an alternative hypothesis is that methane carbon may derive from <ce:sup loc="post">13</ce:sup>C-enriched carbonates occurring below the Samail ophiolite nappe, a hypothesis not considered by Miller et al.</ce:simple-para></ce:abstract-sec></ce:abstract></dm:abstracts>