Bio-optical characterization and light availability parametrization in two glacial melt water influenced estuary systems (West-Greenland)

Abstract

Estuary systems are well-defined semi-enclosed systems which are strongly influenced by their terrestrial and marine boundaries. In this paper we investigate the bio-optical conditions in the water column of two neighboring estuary systems, Uummannaq Fjord and Vaigat–Disko Bay, in West Greenland. Though close to each other, the systems differ by their hydrographic structure influencing the bio-optical conditions and subsequently the biological activities. Both systems show high inorganic suspended particulate matter (SPMi) concentrations near freshwater respective melt water influxes (max. of 15.28 mg L−1 at the surface) and low colored dissolved organic matter (aCDOM@350 nm, −1) abundance throughout the estuaries. Chlorophyll as an indicator of phytoplankton was solely high in the Vaigat (max. of 11.44 μg L−1) representing the outflow arm of the Disko Bay. Light penetration depth as indicated by the 1 % depth of Photosynthetically Available Radiation (PAR) was dominated by chlorophyll and SPMi alike and reached from 12.2 to 41.2 m. Based on these characteristics an effective two component parameterization for the diffuse attenuation coefficient kPAR was developed enabling to model light penetration depth as a relevant factor for bio-optical studies in Arctic environments under glacial melt water influence.