, Volume 9, Issue 1, pp 2–8 | Cite as

Distribution of natural uranium, thorium, lead, and polonium radionuclides in tidal phases of a Delaware salt marsh

  • T. M. Church
  • M. Bernat
  • P. Sharma


Natural radionuclides in the uranium and thorium series were measured in solid tidal phases (suspended particles, bottom sediment, surface microlayer colloids) of a salt marsh in lower Delaware. The purpose was to identify potential processes responsible for trace element cycling (sources, redistribution and exchange) in salt water marshes and with their coastal waters. Generally, concentrations of U, Th,210Pb, and210Po on the tidal solid phases suggest a general mechanism by which tidal marshes appear to be trapping the nuclides into their interiors. The processes may include transport of enriched fine particles into the marsh, capture by salt marsh grass and chemical fixation by redox processes at the sediment surface. Specifically, the uranium contents of most of the samples are similar with activity ratios234U238U≧1, indicating a mixture of detrital and nondetrital (authigenic) uranium inputs such as seawater or ground water. Since the230Th daughter is generally deficient by about 50%, the authigenic enrichment process appears to favor uranium and is potentially linked to the extensive diagenetic sulfur redox cycle of salt marsh sediments. The210Po/210Pb activity ratio is less than one on Spartina adsorbed solids, and could suggest a general process in salt marshes which favors210Pb enrichment by atmospheric fallout over enrichment of210Po on time scales of weeks which correspond to complete tide marsh exchange. A228Th/232Th activity ratio of less than unity on the solids adsorbed onto marsh grass suggests a net process whereby diffusive loss of the intermediate daughter228Ra from the adsorbed solids to tidal waters dominates over potential228Th scavenging by suspended sediment.


Uranium Salt Marsh Activity Ratio Tidal Water Tidal River 
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Literature Cited

  1. Anderson, R. F., andA. P. Fleer. 1982. Determination of natural actinides and plutonium in marine particulate material.Anal. Chem. 54:1142–1147.CrossRefGoogle Scholar
  2. Bacon, M. P., andA. E. Elzerman. 1980. Enrichment of210Pb and210Po in the sea-surface microlayer.Nature 284:332–334.CrossRefGoogle Scholar
  3. Boulegue, J., C. J. Lord, andT. M. Church. 1982. Sulfur speciation and associated trace metals (Fe, Cu) in the pore waters of Great Marsh, Delaware.Geochim. Cosmochim. Acta 46:453–464.CrossRefGoogle Scholar
  4. Borole, D. V., S. Krishnaswami, andB. L. K. Somayajulu. 1982. Uranium isotopes in rivers, estuaries and adjacent coastal sediments of western India; their weathering, transport, and oceanic budget.Geochim. Cosmochim. Acta 46:125.CrossRefGoogle Scholar
  5. Church, T. M., C. J. Lord, III, andB. L. K. Somayajulu. 1981. Uranium, thorium and lead isotopes in a Delaware salt marsh sediment.Estuarine Coastal Shelf Sci. 13:267.CrossRefGoogle Scholar
  6. Elsinger, R., andW. Moore. 1983.224Ra and228Ra and226Ra in the Winyah Bay, and Delaware Bay.Earth Planet. Sci. Lett. 64:430–437.CrossRefGoogle Scholar
  7. Flynn, W. W. 1968. The determination of low levels of polonium-210 in environmental materials.Anal. Chim. Acta 43:221–227.CrossRefGoogle Scholar
  8. Giblin, A. E, andR. W. Howarth. 1984. Pore water evidence for a dynamic sedimentary iron cycle in salt marshes.Limnol. Oceanogr. 29:47–63.Google Scholar
  9. Heyraud, M., andR. D. Cherry. 1983. Correlation of210Po and210Pb enrichments in the sea-surface microlayer.Cont. Shelf Res. 1:283.CrossRefGoogle Scholar
  10. Howarth, R. W., andJ. Teal. 1979. Sulfate reduction in a New England salt marsh.Limnol. Oceanogr. 24:999–1013.CrossRefGoogle Scholar
  11. Krishnaswami, S., andM. M. Sarin. 1976. Procedures for the simultaneous determination of Th, Pu, Ra isotopes210Pb,55Fe,32Si, and14C in marine suspended phases.Anal. Chim. Acta 83:143–156.CrossRefGoogle Scholar
  12. Lion, L. W., andJ. O. Leckie. 1982. Accumulation and transport of Cd, Cu, and Pb in an estuarind surface microlayer.Limnol. Oceanogr. 27:111–125.Google Scholar
  13. Lion, L. W., R. W. Harvey, andJ. O. Leckie 1982 Mechanisms for trace metal enrichment at the surface microlayer in an estuarine salt marsh.Mar Chem. 11:235–244.CrossRefGoogle Scholar
  14. Lord, III,C. J., andT. M. Church. 1983. The geochemistry of salt marshes: sedimentary ion diffusion sulfate reduction, and pyritization.Geochim. Cosmochim. Acta 47:1381–1391.CrossRefGoogle Scholar
  15. Pellenbarg, R., andT. M. Church. 1979. The estuarine surface microlayer and trace metal cycling in salt marshes.Science 203:1010–1012.CrossRefGoogle Scholar
  16. Thompson, J., andK. K. Turekian. 1976.210Po and210Pb distribution in ocean water profiles from the eastern South Pacific.Earth Planet. Sci. Lett. 32: 297–303.CrossRefGoogle Scholar
  17. Tramontano, J. M., andT. M. Church. 1984. A technique for the removal of estuarine seston from Nuclepore filters.Limnol. Oceanogr. 29:1339–1341.Google Scholar

Copyright information

© Estuarine Research Federation 1986

Authors and Affiliations

  • T. M. Church
    • 1
  • M. Bernat
    • 2
  • P. Sharma
    • 3
  1. 1.College of Marine StudiesUniversity of DelawareNewark
  2. 2.Laboratoire de Geologie et GeochimieUniversite de NiceNice CedexFrance
  3. 3.Physical Research Laboratory NayrangpuraAhmedabadIndia

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