Composition of dissolved and suspended matter transported by the Sagavanirktok, Kuparuk and Colville rivers in the Alaskan Arctic.

摘要

Arctic rivers discharge 40 to 80% of their annual volume of water and as much as 70% of their annual load of suspended solids during spring floods in May, June and July. Intensive sampling of the Sagavanirktok, Kuparuk and Colville rivers in the Alaskan Arctic was carried out to address questions related to chemical weathering in the Arctic and transport of dissolved and particulate chemical species to the coastal Beaufort Sea. Concentrations of dissolved organic carbon (DOC) increased from 167 μM to 742 μM during peak discharge in the Sagavanirktok River, at the same time that river flow increased by 250%. Concentrations of dissolved Cu, Pb, Zn and Fe in the Sagavanirktok River followed trends observed for DOC with 3 to 25 fold higher concentrations at peak flow. Similar trends were observed in the Kuparuk and Colville rivers, where average concentrations of dissolved metals and DOC were even higher. This pulse of water carries at least half of the annual load of DOC and dissolved Cu, Fe, Pb and Zn to the coastal Beaufort Sea in ∼3 weeks. Concentrations of particulate metals were more uniform than observed for dissolved metals.; Concentrations of dissolved and particulate Ba vary by a factor of 2 to 3 among rivers; however concentrations of dissolved Ba change in proportion to concentrations of particulate Ba. The distribution coefficient (K _d) for Ba averaged 2.3 to 2.6 × 104 for samples from all three rivers suggesting that concentrations of dissolved Ba are controlled by a quasi-equilibrium between river particles and river water.; Major ion composition for the Sagavanirktok, Kuparuk and Colville rivers was determined during spring floods. Concentrations of Ca2+, Mg2+ and CA account for >80% of the dissolved solids showing that carbonates are the dominant rock type weathered. Concentrations of dissolved Si (50 μM) are significantly lower than concentrations found in the Yukon River (∼150 μM) suggesting that weathering of silicates is inhibited by the colder, more arid conditions or that silicates are less abundant in the Brooks Range and the arctic coastal plain.