These observations highlight the influence of the complex environment
in the fjord waters compared to the synthetic NaCl solution. A detailed
analysis of the natural fjord water sample is shown in Table S3.
The total organic carbon content was high (277 μM) compare to the
values usually found in seawaters (b80 μM). Fluorescence dissolved organic
matter (FDOM) and chromophoric dissolved organic matter
(CDOM) analyses confirm the presence of different types of organic
compounds in solution. The position of the emission and excitation
bands shown in FDOM measurements (Fig. S8a) corresponded to fluorescent
species from different sources: terrestrial humic-like (A-peak)and terrestrial fulvic-like (C-peak), in agreement with other reports for
fjord waters (Coble, 2007; Ishii and Boyer, 2012). CDOMfromfjord waters
represents a complex pool of substances rich in humic/fulvic materials
that originate from terrestrial sources. A CDOM absorption
coefficient, a355, of 2.55 m−1 was obtained at 355 nm. Absorption is a
proxy for the concentration, while the spectral slope, S = 0.010 nm−1
(between 280 and 312 nm), describes the steepness of the spectrum
and is used to account differences in CDOM composition (Fig. S8b).
Both measurements, CDOM and FDOM, showed high terrestrially
derived organic matter inputs (Sulzberger and Durisch-Kaiser, 2009).