Linking CDOM spectral absorption to dissolved organic carbon concentrations and loadings in boreal estuaries

Eero Asmala, Colin A. Stedmon, David N. Thomas

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The quantity of chromophoric dissolved organic matter (CDOM) and dissolved organic carbon (DOC) in three Finnish estuaries (Karjaanjoki, Kyrönjoki and Kiiminkijoki) was investigated, with respect to predicting DOC concentrations and loadings from spectral CDOM absorption measurements. Altogether 87 samples were collected from three estuarine transects which were studied in three seasons, covering a salinity range between 0 and 6.8, and DOC concentrations from 1572 μmoll−1 in freshwater to 222μmoll−1 in coastal waters. CDOM absorption coefficient, aCDOM(375) values followed the trend in DOC concentrations across the salinity gradient and ranged from 1.67 to 33.4 m−1. The link between DOC and CDOM was studied using a range of wavelengths and algorithms. Wavelengths between 250 and 270 nm gave the best predictions with single linear regression. Total dissolved iron was found to influence the prediction in wavelengths above 520nm. Despite significant seasonal and spatial differences in DOC–CDOM models, a universal relationship was tested with an independent data set and found to be robust. DOC and CDOM yields (loading/catchment area) from the catchments ranged from 1.98 to 5.44gCm−2yr−1, and 1.67 to 11.5aCDOM(375)yr−1, respectively.
Original languageEnglish
JournalEstuarine, Coastal and Shelf Science
Volume111
Pages (from-to)107-117
ISSN0272-7714
DOIs
Publication statusPublished - 2012

Keywords

  • dissolved organic carbon
  • chromophoric dissolved organic matter
  • riverine organic loading
  • absorption coefficient
  • estuarine gradient

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