Methods for biogeochemical studies of sea ice: the state of the art, caveats, and recommendations
Miller, LA and Fripiat, F and Else, BGT and Bowman, JS and Brown, KA and Collins, RE and Ewert, M and Fransson, A and Gosselin, M and Lannuzel, D and Meiners, KM and Michel, C and Nishioka, J and Nomura, D and Papadimitriou, S and Russell, LM and Sorensen, LL and Thomas, DN and Tison, J-S and van Leeuwe, MA and Vancoppenolle, M and Wolff, EW and Zhou, J, Methods for biogeochemical studies of sea ice: the state of the art, caveats, and recommendations, Elementa, 3 Article 000038. ISSN 2325-1026 (2015) [Refereed Article]
Over the past two decades, with recognition that the oceanís sea-ice cover is neither insensitive to climate change nor a barrier to light and matter, research in sea-ice biogeochemistry has accelerated significantly, bringing together a multi-disciplinary community from a variety of fields. This disciplinary diversity has contributed a wide range of methodological techniques and approaches to sea-ice studies, complicating comparisons of the results and the development of conceptual and numerical models to describe the important biogeochemical processes occurring in sea ice. Almost all chemical elements, compounds, and biogeochemical processes relevant to Earth system science are measured in sea ice, with published methods available for determining biomass, pigments, net community production, primary production, bacterial activity, macronutrients, numerous natural and anthropogenic organic compounds, trace elements, reactive and inert gases, sulfur species, the carbon dioxide system parameters, stable isotopes, and water-ice-atmosphere fluxes of gases, liquids, and solids. For most of these measurements, multiple sampling and processing techniques are available, but to date there has been little intercomparison or intercalibration between methods. In addition, researchers collect different types of ancillary data and document their samples differently, further confounding comparisons between studies. These problems are compounded by the heterogeneity of sea ice, in which even adjacent cores can have dramatically different biogeochemical compositions. We recommend that, in future investigations, researchers design their programs based on nested sampling patterns, collect a core suite of ancillary measurements, and employ a standard approach for sample identification and documentation. In addition, intercalibration exercises are most critically needed for measurements of biomass, primary production, nutrients, dissolved and particulate organic matter (including exopolymers), the CO2 system, air-ice gas fluxes, and aerosol production. We also encourage the development of in situ probes robust enough for long-term deployment in sea ice, particularly for biological parameters, the CO2 system, and other gases.