Optical properties of chromophoric dissolved organic matter (CDOM) in the Bering Strait and Chukchi Sea

Chromophoric dissolved organic matter (CDOM) is dissolved organic matter that absorbs solar radiation ≥290 nm. Most attenuation of UV radiation in oceans is due to CDOM absorption, and CDOM also regulates light availability to aquatic ecosystems. This work compares Arctic CDOM from the Bering Strait/Chukchi Sea to CDOM in lower latitude waters. Coastal absorbance coefficients at 350 nm (a350) were up to 1.5m-1, and most marine a350 were lower, as expected, at <0.6m -1. An exponential equation was fit to absorbance coefficient spectra, and the spectral slope (S) was used to characterize CDOM of different water masses. Coastal S values ranged from 0.0126 to 0.0245nm -1, similar to CDOM in other coastal regions. Marine S ranged from 0.0098 to 0.0327nm-1, with average values uniquely low (surface 0.0150 nm-1 and deep 0.0135 nm-1). Marine S values varied inversely with a 375, as for CDOM in the Greenland Sea.