Microbiological and biogeochemical investigation of the water column of oligotrophic Lake Baikal at the sites of the K2 and Bolshoi mud volcanoes and the Gorevoy Utes oil seep was carried out in July 2013. Total microbial numbers (TMN), cell numbers of type I and type II methanotrophs, and methane con centrations were measured; the rate of methane oxidation was determined. Methane concentrations in Lake Baikal water column varied from 0.09 to 1 µL/L, while methane oxidation rates varied from 0.007 to 0.9 nL/(L day). The highest rates of methane oxidation were revealed in the near bottom water horizons at the sites of the Bolshoy mud volcano and the Gorevoy Utes oil seep. These were the sites where the most pro nounced anomalies in methane concentration were also detected. TMN varied from 0.123 × 10 6 to 1.64 × 10 6 cells/mL. Methanotrophic bacteria were revealed in the water column at all sites, their abundance did not always correlate with methane concentrations and the rates of methane oxidation. Methanotrophs consti tuted not more than 1.63% of the total microbial number, with their highest abundance in the upper 200 m of the water column.

SIM.QM-S7 was performed to assess the analytical capabilities of National Metrology Institutes (NMIs) and Designated Institutes (DIs) of SIM members (or other regions) for the accurate determination of trace metals in drinking water. The study was proposed by the coordinating laboratories National Research Council Canada (NRC) and Centro Nacional de Metrologia (CENAM) as an activity of Inorganic Analysis Working Group (IAWG) of Consultative Committee for Amount of Substance - Metrology in Chemistry and Biology (CCQM). Participants included 16 NMIs/DIs from 15 countries. No measurement method was prescribed by the coordinating laboratories. Therefore, NMIs used measurement methods of their choice. However, the majority of NMIs/DIs used ICP-MS. This SIM.QM-S7 Supplementary Comparison provides NMIs/DIs with the needed evidence for CMC claims for trace elements in fresh waters and similar matrices. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).