Mercury Transport in a Low-Arctic River in Kobbefjord, West Greenland (64° N)
2012
Søndergaard, Jens | Riget, Frank | Tamstorf, Mikkel P. | Larsen, Martin M.
Mercury (Hg) transport was studied in a river in Kobbefjord, near Nuuk in West Greenland, during the 2009 and 2010 summer periods. The river drains an area of 32 km², and the Kobbefjord area is considered representative to low-Arctic West Greenland. The river water origins from both precipitation and melting of small glaciers and annual water discharges for 2009 and 2010 were estimated to be 29 and 26 million m³, respectively. Mean Hg concentrations (±SD) were 0.46 ± 0.17 and 0.26 ± 0.17 ng L⁻¹ for 2009 and 2010. The annual Hg transport was estimated to 14 and 6.4 g, corresponding to a transport rate of 0.45 and 0.20 g Hg km⁻² year⁻¹ from the river basin. The highest Hg concentrations (up to 1.0 ng L⁻¹) and discharges were measured in spring 2009 along with melting of extensive amounts of snow deposited during the 2008–2009 winter period. In contrast, the following 2009–2010 winter period was relatively dry with less snowfall. This indicates that a major fraction of the Hg in this area is likely to come from Hg deposited along with winter precipitation (as wet deposition) released upon snowmelt. Also, the results show that while Hg concentrations were low in Kobbefjord River compared to other sub-Arctic/Arctic rivers, the annual Hg transport rates from the basin area were within the range reported for other sub-Arctic/Arctic areas.
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