Strontium and its isotopes in Canadian rivers: Fluxes and global implications |
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Authors: | Moire A Wadleigh Ján Veizer Christopher Brooks |
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Institution: | Derry Laboratory, Department of Geology, University of Ottawa, Ottawa, Canada KIN 6N5;Département de Géologie, Université de Montréal, Montréal, Canada H3C 3J7 |
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Abstract: | Systematic sampling of the 39 largest Canadian rivers shows that the weighted average ratio in the dissolved load is 0.7111, similar to previous measurements on such large rivers as the Amazon and Mississippi. Consequently, we believe that the above estimate is likely representative of the global average. This imposes a limit of 6.5 × 1011g yr?1 on the amount of Sr exchanged with basalts in hydrothermal cells on mid-oceanic ridges. Evaluation of geological information suggests that Sr from silicate sources is of considerable importance for all but the largest Canadian rivers. The latter have chemical and isotopic composition consistent with ~4:1 carbonate vs. silicate derivation of Sr, but such interpretation is not unique. In terms of their water discharge, the 39 Canadian rivers studied account for 4.2% of the world total and their weighted average concentrations for other dissolved solutes are: TDS 176 ppm, Ca 18 ppm, Cl 6.8 ppm and Sr 84 ppb. |
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