Spatial Distribution of Colored Dissolved Organic Matter in the Western Arctic Ocean

Xiaoxia Cai,Yanpei Zhuang,Jing Xu,Jianfang Chen,Hongliang Li,Haiyan Jin

doi:10.3390/jmse10030352

Abstract

Optical properties of colored dissolved organic matter (CDOM) were investigated along a latitudinal transect (67°–77° N) in upper water (<80 m depth) of the western Arctic Ocean. The absorption coefficient at 280 nm was 0.48–1.25 m−1, with the average for the oligotrophic basin area (1.04 ± 0.08 m−1) being slightly higher than that of the productive shelf area (0.95 ± 0.16 m−1), implying a decoupling effect between CDOM concentration and biological productivity in the western Arctic Ocean. The spectral slope coefficient S270–350 was negatively correlated with salinity, indicating that DOM molecular weight increases with salinity, and may be affected by melt-water input. Four fluorescent components were identified by excitation emission matrices elaborated by parallel factor analysis, including three humic-like (C1, C3, and C4) components and one protein-like (C2) component. Significant increases in concentrations of terrestrially derived humic-like C3 and C4 components with salinity were observed in the basin, mainly controlled by the physical mixing of surface fresh water and subsurface inflowing Pacific Ocean water. Terrestrial material carried by Pacific inflow is thus an important factor affecting the distribution of CDOM fluorescence components. The C3 and C4 fluorescence components may be useful as tracers of Pacific water in the western Arctic Ocean.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
The magnitudes of biogeochemical variables are usually greater in shelf than basin areas of the western Arctic Ocean, for nutrient concentration [11], primary production [14], and particulate organic carbon concentrations [30], which are associated with productive and oligotrophic systems
Colored dissolved organic matter (DOM) (CDOM) absorption coefficient in the shelf area were significant different from and slightly lower than in the basin (Figure 6), which is inconsistent with the high shelf primary productivity

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Marine dissolved organic matter (DOM) constitutes one of the largest reduced carbon reservoirs on Earth and is actively involved in the carbon cycle, marine food webs, and climatic effects [1]. Colored DOM (CDOM) is the chromophoric fraction of DOM with light-absorbing properties in the oceans [2]. Sources of marine CDOM include terrestrial input, in situ oceanic production, and sediments [3–5], with its removal occurring mainly through photodegradation and microbial degradation [3]. Production and removal of CDOM affect light attenuation and biological metabolism in the oceans

Methods

Results

Discussion

Conclusion