Major Ions

Tremendous numbers of coastal lakes and ponds in the Arctic are influenced by sea spray, particularly within ^20-30 km of the coast. The ratios of major ions such as Na+, Cl3, and K+ in these lakes are similar to ratios found in seawater, with the exception that Ca2+ and HCO3 tend to be enriched over sea-water owing to inputs from weathering or most often from blowing soil (loess). Atmospheric inputs have little influence on the more inland lakes, however, which in all landscapes tend to be enriched in bicarbonate and cations (relative to Cl_) compared with ratios in rain.

The second major factor influencing water chemistry is the time since last glaciation of the landscape, broadly characterized by younger soils and more recently exposed rocks with higher carbonate mineral content and pH, versus older, more weathered rocks and acidic soils. For example, Ca:Cl and Mg:Cl ratios are typically 3-5 times higher in lakes on younger than on older glacial surfaces. This influence is found circumpolar, and reflects the geographic asymmetry in Pleistocene glaciations, where much of the North American and European arctic had young land surfaces exposed by recession of the last continental or mountain-glacier ice sheets (<15 000 a BP), whereas much of Siberia to far northwestern Canada had older surfaces (>100 000 a BP) unglaciated during the late-Quaternary.

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