The Geochemistry of Gallium Relative to Aluminum in Californian Streams

Document Type

Article

Publication Date

4-1-1996

Department

Geography and Geology

School

Biological, Environmental, and Earth Sciences

Abstract

The possibility that the chemically similar elements Ga and Al might be fractionated during the weathering process was examined. Gallium and Al were determined in waters, source rocks, and soils in a variety of weakly basic small stream drainages in California. As expected from the low mobility of these two elements (and in agreement with previous work), little difference was found between Ga/Al ratios in source rocks and weathered residuals. However, dissolved Ga/Al ratios were consistently higher than the Ga/Al ratios of solids from the same stream basin. Evidence suggests that neither anthropogenic effects nor presence of trace sulfide minerals are likely explanations for the dissolved Ga/Al enrichment. Comparisons of Ga/Al ratios with major elements indicate that the nature and intensity of chemical weathering plays an important role in determining the dissolved Ga/Al ratio. Organic complexation of Al can also affect the dissolved Ga/Al ratio, even in weakly basic streams.

Publication Title

Geochimica et Cosmochimica Acta

Volume

60

Issue

8

First Page

1323

Last Page

1328

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