Dissolved Organic Carbon (DOC) and Some Other Chemical Profiles of Various Alaskan Lakes in Summer

Abstract

This paper presents the first attempt at determining dissolved organic carbon (DOC) in lake waters covering the vast Alaskan area from the northernmost arctic coast through the subarctic to the maritime region.
Based on the water chemistry, Alaskan lakes examined are classified into four groups. 1) Brackish water lakes: Distributed near the seacoast. The DOC level was low to moderate (1.7-5.9 mgC⋅l^-1). Water had measurable salinity. 2) Colored water lakes: Dominant in the arctic and interior Alaska. The concentration of DOC was as high as 7-46 mgC⋅l^-1. TN and TP were eutrophic to hypertrophic levels, while Chl. a was oligotrophic to eutrophic levels, which indicates the predominant contribution of biologically unavailable forms of N and P, including organic ones, to the TN and TP pools. The uniqueness of Alaskan colored waters, including arctic bog waters on the tundra, lies in their nearly neutral pH in comparison with a low pH of around 4 for colored bog waters elsewhere in the world. 3) Clear water lakes: Distributed mainly in interior Alaska and southward. The DOC level was 1.1-19.5 mgC⋅l^-1. 4) Glacier meltwater lakes: Distributed mainly in the maritime as well as the transitional region between maritime and continental climates. A large amount of glacial silt makes the lake water turbid and characteristically gray in color. The DOC concentration (1.1-1.5 mgC⋅l^-1) was lower than that in any other group.