The optics of chromophoric dissolved organic matter (CDOM) in the Greenland Sea: An algorithm for differentiation between marine and terrestrially derived organic matter

Abstract

The optics of chromophoric dissolved organic matter (CDOM) in the Greenland Sea were investigated and compared to results from earlier studies in the Southeastern North Sea. Absorption at 375 nm (a375) in the Greenland Sea varied from 0.77 m-1 to the detection limit of our instrument (0.05 m-1), with the highest values found during summer. The spectral slope coefficient (S) ranged from 8.2 to 26.4 μm-1 with the highest values occurring during winter. Seasonal variations in the in situ production and degradation of CDOM where shown to be responsible for the trends seen. A negative correlation between S and a375 was evident in the Greenland Sea and differed noticeably from that found in coastal waters. The differing S-a375 behavior of CDOM known to be of terrestrial origin allowed the development of an algorithm for the differentiation between marine and terrestrial organic matter The behavior of marine CDOM was modeled by S = 7.4 + 1.1/a375.