6533b872fe1ef96bd12d42d1

RESEARCH PRODUCT

Selective incorporation of dissolved organic matter (DOM) during sea ice formation

Louiza NormanAnssi V. VähätaloSusann MüllerShazia N. AslamDavid N. ThomasMats A. GranskogGraham J. C. UnderwoodGerhard DieckmannColin A. Stedmon

subject

0106 biological sciencesgeographygeography.geographical_feature_category010504 meteorology & atmospheric sciencesChemistry010604 marine biology & hydrobiologySize-exclusion chromatographyta1171General ChemistryOceanography01 natural sciencesColored dissolved organic matterBrineEnvironmental chemistrySpectral slopeDissolved organic carbonSea iceEnvironmental ChemistrySeawaterChemical composition0105 earth and related environmental sciencesWater Science and Technology

description

This study investigated the incorporation of DOM from seawater into >2 day-old sea ice in tanks filled with seawater alone or amended with DOM extracted from the microalga, Chlorella vulgaris. Optical properties, including chromophoric DOM (CDOM) absorption and fluorescence, as well as concentrations of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), dissolved carbohydrates (dCHOs) and dissolved uronic acids (dUAs) were measured. Enrichment factors (EFs), calculated from salinity-normalized concentrations of DOM in bulk ice, brine and frost flowers relative to under-ice water, were generally >1. The enrichment factors varied for different DOM fractions: EFs were the lowest for humic-like DOM (1.0–1.39) and highest for amino acid-like DOM (1.10–3.94). Enrichment was generally highest in frost flowers with there being less enrichment in bulk ice and brine. Size exclusion chromatography indicated that there was a shift towards smaller molecules in the molecular size distribution of DOM in the samples collected from newly formed ice compared to seawater. Spectral slope coefficients did not reveal any consistent differences between seawater and ice samples. We conclude that DOM is incorporated to sea ice relatively more than inorganic solutes during initial formation of sea ice and the degree of the enrichment depends on the chemical composition of DOM

https://doi.org/10.1016/j.marchem.2013.06.008