The geochemistry of river particulates from the continential USA: Major elements
- Odense Univ. (Denmark)
River particulates have been collected from twenty-three rivers from throughout the continental USA. The rivers drain mostly large basins (basin areas range from 2.1 x 10{sup -3} to 2970 x 10{sup 3} km{sup 2}) composed of mixed lithologies, and spanning a wide range of climatic conditions as evidenced by a large variation in air and ground water temperatures, precipitation, and runoff. Suspended particulates have been analyzed for organic and inorganic carbon, as well as the major elements Al, Fe, Mn, K, Si, Ca, Mg, and Na. Also determined were suspended sediment loads at the time of sampling, particle surface areas, and grain size distributions. Five-year average river water chemistry and suspended sediment concentrations, obtained from USGS water supply reports, are also included as supporting information. Particle chemistry systematically varies with rates of runoff, with high runoff rivers transporting the most heavily altered particulates and low runoff rivers carrying the least altered. Degrees of alteration are indicated by the extent to which the refractory, nonmobile elements Al and Fe are concentrated into the particulates and the extent to which the most easily weathered elements Na, Ca, and Mg have been leached. Overall, the susceptibility of elements towards leaching is consistent with numerous previous descriptions of element mobility on weathering. A simple predictive model has been developed to explore and explain the observed trends between particle composition and river runoff. Hence, the composition of river particulates depends both on the climate parameters of runoff and temperature (as they control dissolved river chemistry) and the nonclimate parameters including elevation, relief, tectonics, and basin area that control the SS load of rivers. 49 refs., 10 figs., 9 tabs.
- OSTI ID:
- 585469
- Journal Information:
- Geochimica et Cosmochimica Acta, Vol. 61, Issue 16; Other Information: PBD: Aug 1997
- Country of Publication:
- United States
- Language:
- English
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