Distributions and Influencing Factors of Dissolved Manganese in Kongsfjorden and Ny-Ålesund, Svalbard

Abstract

The contributions of polar glaciers to the global distribution of trace metals have attracted an increasing amount of attention due to global warming. To better understand the distributions and influencing factors of dissolved manganese (dMn) in the Arctic, samples were collected in Ny-Ålesund and Kongsfjorden in Svalbard in August 2013. dMn concentrations in the drainage basin of the Bayelva River, of which the average value was 216.4 ± 54.2 nM (n = 16) and higher than that in other polar rivers and lakes, showed no significant differences from upstream to downstream in August. dMn varied differently at certain stations in the mainstream of Bayelva River on different days due to complex factors in the polar region, e.g., topography, tributaries, groundwater, organic matter content, and runoff fluxes. It was estimated that the scale length (distance from the initial concentration to 1/e) of dMn in the coastal area of the Bayelva River was 1050 m, indicating that the influence of Bayelva River on the distributions of dMn in Kongsfjorden was insignificant. Affected by high-dMn concentration tidewater glacier meltwater (∼581.1 nM) in the inner fjord, dMn showed an increasing trend from the fjord entrance to the inner zone in the surface layer of Kongsfjorden. Furthermore, the longer scale length (4.25 km) and overlying relatively large discharge suggested a higher incidence of tidewater glaciers in Kongsfjorden. The vertical distributions of dMn presented obvious stratification, with higher dMn at the surface (80.9 ± 53.7 nM, n = 21) and lower dMn below the surface (12.6 ± 2.4 nM, n = 11). Combined with the water mass properties and flow field, the distributions of dMn in Kongsfjorden were mainly controlled by relatively high dMn concentrations, low-salinity surface water, relatively low dMn concentrations, and high-salinity Atlantic water mixing. The dMn concentrations in Ny-Ålesund and Kongsfjorden were significantly higher than those in the North Atlantic Ocean and Arctic Ocean around Svalbard. Tidewater glaciers (Kongsvegen, Kronebreen, and Kongsbreen) and glaciers of Svalbard were estimated to export 0.46 and 74 Mmol/year of dMn, which was comparable to other sources to the Arctic Ocean. The contributions of glaciers to the distributions of dMn in the Arctic and global Ocean were expected to be increasingly significant considering the increasing amount of glacier meltwater in the context of global warming.

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