Aquatic Geochemistry

, Volume 1, Issue 1, pp 1–34 | Cite as

The aquatic chemistry of rare earth elements in rivers and estuaries

  • Edward R. Sholkovitz
Article

Abstract

Laboratory experiments were carried out to determine how pH, colloids and salinity control the fractionation of rare earth elements (REEs) in river and estuarine waters. By using natural waters as the reaction media (river water from the Connecticut, Hudson and Mississippi Rivers) geochemical reactions can be studied in isolation from the large temporal and spatial variability inherent in river and estuarine chemistry. Experiments, field studies and chemical models form a consistent picture whereby REE fractionation is controlled by surface/solution reactions. The concentration and fractionation of REEs dissolved in river waters are highly pH dependent. Higher pH results in lower concentrations and more fractionated composition relative to the crustal abundance. With increasing pH the order of REE adsorption onto river particle surfaces is LREEs > MREEs > HREEs. With decreasing pH, REEs are released from surfaces in the same order. Within the dissolved (<0.22 µm) pool of river waters, Fe-organic colloids are major carriers of REEs. Filtration through filters and ultrafilters with progressively finer pore sizes results in filtrates which are lower in absolute concentrations and more fractionated. The order of fractionation with respect to shale, HREEs > MREEs > LREEs, is most pronounced in the solution pool, defined here as <5K and <50K ultrafiltrates. Colloidal particles have shale-like REE compositions and are highly LREE enriched relative to the REE composition of the dissolved and solution pools. The addition of sea water to river water causes the coagulation of colloidal REEs within the dissolved pool. Fractionation accompanies coagulation with the order of sea water-induced removal being LREEs > MREEs > HREEs. While the large scale removal of dissolved river REEs in estuaries is well established, the release of dissolved REEs off river particles is a less studied process. Laboratory experiments show that there is both release and fractionation of REEs when river particles are leached with seawater. The order of sea water-induced release of dissolved REE(III) (LREEs > MREEs > HREEs) from Connecticut River particles is the same as that associated with lowering the pH and the same as that associated with colloidal particles. River waters, stripped of their colloidal particles by coagulation in estuaries, have highly evolved REE composition. That is, the solution pool of REEs in river waters are strongly HREE-enriched and are fractionated to the same extent as that of Atlantic surface seawater. This strengthens the conclusions of previous studies that the evolved REE composition of sea water is coupled to chemical weathering on the continents and reactions in estuaries. Moreover, the release of dissolved Nd from river particles to sea water may help to reconcile the incompatibility between the long oceanic residence times of Nd (7100 yr) and the inter-ocean variations of the Nd isotopic composition of sea water. Using new data on dissolved and particle phases of the Amazon and Mississippi Rivers, a comparison of field and laboratory experiments highlights key features of REE fractionation in major river systems. The dissolved pool of both rivers is highly fractionated (HREE enriched) with respect to the REE composition of their suspended particles. In addition, the dissolved pool of the Mississippi River has a large negative Ce-anomaly suggesting in-situ oxidation of Ce(III). One intriguing feature is the well developed maximum in the middle REE sector of the shale normalized patterns for the dissolved pool of Amazon River water. This feature might reflect competition between surface adsorption and solution complexation with carbonate and phosphate anions.

Key words

Rivers estuaries rare earth elements colloids Amazon River Mississippi River Connecticut River 

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References

  1. Banfield, J. F. and Eggleton, R. A. (1989) Apatite replacement and rare earth mobilization, fractionation and fixation during weathering.Clays and Clay Minerals 37, 113–127.Google Scholar
  2. Braun, J. J., Pagel, M., Muller, J. P., Bilong, P., Michard, A., and Guillet, B. (1990) Cerium anomalies in lateritic profiles.Geochim. Cosmochim. Acta 54, 781–895.Google Scholar
  3. Braun, J. J., Pagel, M., Herbillon, A., and Rosin, C. (1993) Mobilization and redistribution of REEs and thorium in a syenetic lateritic profile: A mass balance study.Geochim. Cosmochim. Acta 57, 4419–4434.Google Scholar
  4. Byrne, R. H. and Kim, K. H. (1990) Rare earth element scavenging in seawater.Geochim. Cosmochim. Acta 54, 2645–2656.Google Scholar
  5. Byrne, R. H., Lee, J. H., and Bingler, L. S. (1991) Rare earth element complexation by PO4−3 ions in aqueous solution.Geochim. Cosmochim. Acta 55, 2729–2735.Google Scholar
  6. Cantrell, K. J. and Byrne, R. H. (1987) Rare earth element complexation by carbonate and oxalate ions.Geochim. Cosmochim. Acta 51, 597–605.Google Scholar
  7. Chase, E. M. and Sayles, F. L. (1980) Phosphorus in suspended sediments of the Amazon River.Est. Coastal Mar. Sci. 11, 383–391.Google Scholar
  8. DeBaar, H. J. W., Schijf, J., and Byrne, R. H. (1991) Solution chemistry of the rare earth elements in seawater.Euro. J. Chem. 28, 357–373.Google Scholar
  9. Duddy, I. R. (1980) Redistribution and fractionation of rare-earth and other elements in a weathering profile.Chem. Geol. 30, 363–381.Google Scholar
  10. Edmond, J. M., Boyle, E. A., Grant, B., and Stallard, R. F. (1981) The chemical mass balance in the Amazon plume: The nutrients.Deep-Sea Res. 28, 1339–1374.Google Scholar
  11. Elderfield, H., Hawkesworth, C. J., and Greaves, M. J. (1981) Rare earth element geochemistry of oceanic ferromanganese nodules and associated sediments.Geochim. Cosmochim. Acta 45, 513–528.Google Scholar
  12. Elderfield, H. (1988) The oceanic chemistry of the rare-earth elements.Phil. Transactions of the Royal Society A325, 105–126.Google Scholar
  13. Elderfield, H., Upstill-Goddard, R., and Sholkovitz, E. R. (1990) The rare earth elements in rivers, estuaries and coastal sea waters: Processes affecting crustal input of elements to the ocean and their significance to the composition of seawater.Geochim. Cosmochim. Acta 54, 971–991.Google Scholar
  14. Erel, Y. and Morgan, J. J. (1993) The effect of surface reactions on the relative abundances of trace metals in deep-ocean water.Geochim. Cosmochim. Acta 55, 1807–1813.Google Scholar
  15. Erel, Y. and Stopler, E. M. (1993) Modeling of rare-earth element partitioning between particles and solution in aquatic environments.Geochim. Cosmochim. Acta 57, 513–518.Google Scholar
  16. Fox, L. E., Sager, S. L., and Wofsy, S. C. (1986) The chemical control of soluble phosphorus in the Amazon estuary.Geochim. Cosmochim. Acta 50, 783–794.Google Scholar
  17. Fox, L. E. (1989) A model for inorganic control of phosphate concentrations in river waters.Geochim. Cosmochim. Acta 53, 417–428.Google Scholar
  18. Fox, L. E. (1990) Geochemistry of dissolved phosphate in the Sepik River and estuary, Papua, New Guinea.Geochim. Cosmochim. Acta 54, 1019–1024.Google Scholar
  19. Fox, L. E. (1991) Phosphorus chemistry in the tidal Hudson River.Geochim. Cosmochim. Acta 55(6), 1529–1538.Google Scholar
  20. Froelich, P. N. (1988) Kinetic control of dissolved phosphate in natural rivers and estuaries: A printer on the phosphate buffer mechanism.Limnol. Oceanogr. 33(4, part 2), 649–668.Google Scholar
  21. Goldstein, S. J. and Jacobsen, S. B. (1987) The Nd and Sr isotopic systematics of river water dissolved material, implications for sources of Nd and Sr in seawater.Chem. Geol. 66, 245–272.Google Scholar
  22. Goldstein, S. J. and Jacobsen, S. B. (1988) Rare earth elements in river waters.Earth Planet. Sci. Lett. 89, 35–47.Google Scholar
  23. Gosselin, D. C., Smith, M. R., Lepel, E. A., and Laul, J. C. (1992) Rare earth elements in chloride-rich groundwater, Palo Duro Basin, Texas, USA.Geochim. Cosmochim. Acta 56, 1495–1505.Google Scholar
  24. Grandjean-Lecuyer, P., Feist, R., and Albarede, F. (1993) Rare earth elements in old biogenic apatites.Geochim. Cosmochim. Acta 57, 2507–2514.Google Scholar
  25. Greaves, M. J., Elderfield, H., and Klinkhammer, G. P. (1989) Determination of the rare earth elements in natural waters by isotope-dilution mass spectrometry.Anal. Chim. Acta 218, 265–280.Google Scholar
  26. Koeppenkastrop, D. and DeCarlo, E. H. (1992) Sorption of rare earth elements from seawater onto synthetic mineral particles: An experimental approach.Chem. Geol. 95, 251–263.Google Scholar
  27. Koeppenkastrop, D. and DeCarlo, E. H. (1993) Uptake of rare earth elements from solutions by metal oxides.Environ. Sci. Technol. 27, 1796–1802.Google Scholar
  28. Landing, W. M. and Lewis, B. L. (1991) Analysis of marine particulate and colloidal material for transition metals, inMarine Particles: Analysis and Characterization (ed. D. C. Hurd and D. W. Spencer), American Geophysical Union, pp. 263–272.Google Scholar
  29. Lee, J. H. and Byrne, R. H. (1992) Examination of comparative rare earth element complexation behavior using linear free-energy relationships.Geochim. Cosmochim. Acta 56, 1127–1138.Google Scholar
  30. Lee, J. H. and Byrne, R. H. (1993) Complexation of trivalent rare earth elements (Ce, Eu, Gd, Tb, Yb) by carbonate ions.Geochim. Cosmochim. Acta 57, 295–302.Google Scholar
  31. Martin, J. M., Hogdahl, O., and Phillippot, J. C. (1976) Rare earth element supply to the oceans.J. Geophys. Res. 81, 3119–3124.Google Scholar
  32. Martin, W. R. and McCorkle, D. C. (1993) Dissolved organic carbon concentrations in marine pore waters determined by high-temperature oxidation.Limnol. Oceanogr. 38(7), 1464–1479.Google Scholar
  33. McArthur, J. M. and Walsh, J. N. (1984/1985) Rare-earth geochemistry of phosphorites.Chem. Geol. 47, 191–220.Google Scholar
  34. Michard, A., Albarede, F., Michard, G., Minster, J. F., and Charlou, J. L. (1983) Rare earth elements and uranium in high-temperature solutions from East Pacific Rise hydrothermal vent field (13°N).Nature 303, 795–797.Google Scholar
  35. Millero, F. J. (1992) Stability constants for the formation of rare earth inorganic complexes as a function of ionic strength.Geochim. Cosmochim. Acta 56, 3123–3132.Google Scholar
  36. Moffett, J. W. (1990) Microbially mediated cerium oxidation in seawater.Nature 345, 421–423.Google Scholar
  37. Moffett, J. W. (1994) A radiotracer study of cerium and manganese uptake onto suspended particles in Chesapeake Bay.Geochim. Cosmochim. Acta 58, 695–703.Google Scholar
  38. Nesbitt, H. W. (1979) Mobility and fractionation of rare earth elements during weathering of a granodiorite.Nature 279, 206–210.Google Scholar
  39. Piepgras, D. J. and Jacobsen, S. B. (1992) The behavior of rare earth elements in seawater: Precise determinations of variations in the North Pacific water column.Geochim. Cosmochim. Acta 56, 1851–1862.Google Scholar
  40. Plunkett, M. L., Morris III, F., and Oakley, W. T. (1992)Water Resources Data, Mississippi, Water Year 1992. U.S. Geological Survey Water-Data Report, MS-92-1, pp. 206–209.Google Scholar
  41. Schneider, D. L. and Palmieri, J. M. (1994)A Method for the Analysis of Rare Earth Elements in Natural Waters by Isotope Dilution Mass Spectrometry. Woods Hole Oceanographic Institution Report, 94–06, 39 pp.Google Scholar
  42. Sholkovitz, E. R. (1976) Fluctuation of dissolved organic and inorganic matter during the mixing of river water and seawater.Geochim. Cosmochim. Acta 40, 831–845.Google Scholar
  43. Sholkovitz, E. R. (1989) Artifacts associated with the chemical leaching of sediments for rare-earth elements.Chem. Geol. 77, 47–51.Google Scholar
  44. Sholkovitz, E. R. (1990) Rare earth elements in marine sediments and geochemical standards.Chem. Geol. 88, 333–347.Google Scholar
  45. Sholkovitz, E. R. (1990) Filtration techniques for river and coastal waters with emphasis on trace elements in anoxic waters, inMarine Particles: Analysis and Characterization (eds. D. C. Hurd and D. W. Spencer), American Geophysical Union, pp. 295–301.Google Scholar
  46. Sholkovitz, E. R. (1992) Chemical evolution of rare earth elements: Fractionation between colloidal and solution phases of filtered river water.Earth Planet. Sci. Lett. 114, 77–84.Google Scholar
  47. Sholkovitz E. R. (1993) The geochemistry of rare earth elements in the Amazon River Estuary.Geochim. Cosmochim. Acta 57, 2181–2190.Google Scholar
  48. Sholkovitz, E. R. and Elderfield, H. (1988) The cycling of dissolved rare earth elements in Chesapeake Bay.Global Biogeochem. Cycles 2, 157–176.Google Scholar
  49. Sholkovitz, E. R. and Schneider, D. L. (1991) Cerium redox cycles and rare earth elements in the Sargasso Sea.Geochim. Cosmochim. Acta 55, 2737–2743.Google Scholar
  50. Sholkovitz, E. R., Shaw, T. J., and Schneider, D. L. (1992) The geochemistry of rare earth elements in the seasonally anoxic water column and pore waters of Chesapeake Bay.Geochim. Cosmochim. Acta 56, 3389–3402.Google Scholar
  51. Sholkovitz, E. R., Landing, W. M. and Lewis, B. L. (1994) Ocean particle chemistry: The fractionation of rare earth elements between suspended particles and seawater.Geochim. Cosmochim. Acta 58, 1567–1580.Google Scholar
  52. Stallard, R. F. and Edmond, J. M. (1983) Geochemistry of the Amazon. 2. The influence of geology and weathering environments on the dissolved load.J. Geophys. Res. 88, 9671–9688.Google Scholar
  53. Stookey, L. L. (1970) Ferrozine — A new spectrophotometric reagent from iron.Anal. Chem. 42, 779–781.Google Scholar
  54. Stordal, M. C. and Wasserburg, G. J. (1986) Neodymium isotopic study of Baffin Bay water: sources of REE from very old terrances.Earth Planet. Sci. Lett. 77, 259–272.Google Scholar
  55. Turner, D. R., Whitfield, M., and Dickson, A. G. (1981) The equilibrium speciation of dissolved components in freshwater and seawater at 25 degrees C and 1 atm pressure.Geochim. Cosmochim. Acta 45, 855–881.Google Scholar
  56. Wood, S. A. (1990) The aqueous geochemistry of the rare-earth elements and yttrium. 1. Review of available low-temperature data for inorganic complexes and the inorganic REE speciation of natural waters.Chem. Geol. 82, 159–186.Google Scholar
  57. Wright, J., Schrader, H., and Hosler, W. T. (1987) Paleoredox variations in ancient oceans recorded by rare earth elements in fossil apatite.Geochim. Cosmochim. Acta 51, 631–644.Google Scholar

Copyright information

© Kluwer Academic Publishers 1995

Authors and Affiliations

  • Edward R. Sholkovitz
    • 1
  1. 1.Marine Chemistry and GeochemistryWoods Hole Oceanographic InstitutionWoods HoleUSA

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