Abstract
210Pb, 234Th and 7Be activities were measured to establish sediment accumulation rates, estimate sediment mixing rates, and determine the depth of the sediment mixed layer in the Sepetiba Bay mangrove ecosystem near Rio de Janeiro City, Brazil. Three sediment cores were collected from Enseada das Garças, a typical exposed tidal flat region with a sequence of sedimentary features. The seaward edge of this sequence is a mud flat with the landward portion covered with Spartina alterniflora followed by mangrove vegetation. An additional core was collected on an overwash island near Barra de Guaratiba, which is cover with mangroves without a mud flat or Spartina alterniflora sequence. Sediment accumulation rates were determined to range up to 1.8 cm/yr with the Spartina alterniflora having the maximum rate. Mixing rates were estimated for the Spartina alternifloracore at 40 cm2/yr based on 210Pb and 7Be from the upper mixed region of the core. The 234Th activity in this core suggested that either mixing or the input of 234Th were not in steady state. The sediment mixed region depth ranged from 4 cm to greater than 30 cm. At the Enseada das Garças site the mixing depth decreased in the landward direction (i.e. mud flats > 30 cm, Spartina alterniflora 11 cm, mangroves 4 cm). Along with this decrease in sediment mixing depth was a shift from physical to biological mixing. The Barra de Guaratiba core had a sediment mixed layer of 13 cm as a result of physical and intense biological activity.
Similar content being viewed by others
References
Aller, R.C. and Cochran, J.K. 1976. 234Th/238U disequilibrium in nearshore sediments: particle reworking and diagenetic time scales. Earth and Planetary Science Letters 29: 37–50.
Aller, R.C., Benninger, L.K. and Cochran, J.K. 1980. Tracking particle-associated processes in nearshore environments by use of 234Th/238U disequilibrium. Earth and Planetary Science Letters, 47: 161–170.
Aller, R.C. 1982. The effects of macrobenthos on chemical properties of marine sediment and overlying water, pp. 53–102. In: McCall, P.L. and Tevesz. M.S.J. (eds), Animal-Sediment Relations. Plenum Press, New York.
Aller, R.C. and DeMaster, D.J. 1984. Estimates of particle flux and reworking at the deep-sea floor using 234Th/238U disequilibrium. Earth and Planetary Science Letters 67: 308–318.
Benninger, L.K., Aller, R.C., Cochran, J.K. and Turekian, K.K. 1979. Effects of biological sediment mixing on the 210Pb chronology and trace metal distribution in a long island sound sediment core. Earth and Planetary Science Letters 43: 241–259.
Berner, R.A. 1980. Early Diagenesis: A Theoretical Approach. Princeton University Press, Princeton, NJ, 241 pp.
Bird, E.C.F. 1971. Mangroves as land-builders. Victorian Naturalist 88: 189–197.
Borges, H.V., Figueiredo, Jr., A.G. and Beisl, C.H. 1989. Baia de Sepetiba-evolucáo geomorfolö nos ultimos 100 anos. In: 1° Simposio de Geologia do Sudeste, Rio de Janeiro, Brazil, pp. 59–60.
Bunt, J.S. 1992. Introduction. In: Robertson, A.I. and Alongi, D.M. (eds), Coastal and Estuarine Studies, Vol. 41, Tropical Mangrove Ecosystems. American Geophysical Union, Washington, DC, pp.1–6.
Carpenter, R., Peterson, M.L., Bennett, J.T. and Somayajulu, B.L.K. 1984. Mixing and cycling of uranium, thorium and 210Pb in Puget Sound sediments. Geochimica et Cosmochimica Acta 48: 1949–1963.
Casey, W.H., Larsen, I.L. and Olsen, C.R. 1986. The distribution of cosmogenic 7Be in salt marsh sediments. Geophysical Research Letters 13: 322–325.
Crusius, J. and Anderson, R.F. 1991. Immobility of 210Pb in Black Sea sediments. Geochimica et Cosmochimica Acta, 55: 327–333.
Cutshall, N.H., Larsen, I.L. and Olsen, C.R. 1983. Direct analysis of 210Pb in sediment samples: self-absorption corrections. Nuclear Instruments and Methods 206: 309–312.
Davis, R.B., Hess, C.T., Norton, S.A., Hanson, D.W., Hoagland, K.D. and Anderson, D.S. 1984. 137Cs and 210Pb dating of sediments from soft-water lakes in New England and Scandinavia, a failure of 137Cs dating. Chemical Geology 44: 151–185.
DeLaune, R.D., Baumann, R.H. and Gosselink, J.G. 1983. Relationships among vertical accretio, coastal submergence, and erosion in a Louisiana Gulf Coast marsh. Journal of Sedimentary Petrology 53: 147–157.
DeMaster, D.J., McKee, B.A., Nittrouer, C.A., Jiangchu, Q. and Guodong, C. 1985. Rates of sediment accumulation and particle reworking based on radiochemical measurements from continental shelf deposits in the East China Sea. Continental Shelf Research 4: 143–158.
FEEMA, 1980. Levantamento de metais pesados do Estado do Rio de Janeiro: Relatörio preliminar-out. Rio de Janeiro, 72 pp.
Feijtel, T.C., DeLaune, R.D. and Patrick, Jr., W.H. 1985. Carbon flow in coastal Louisiana. Marine Ecology Prog. Series 24: 255–260.
Hatcher, B.G., Johannes, R.E., and Robertson, A.I. 1989. Review of research relevant to conservation of shallow tropical marine ecosystems. Oceanography and Marine Biology: An Annual Review 27: 337–414.
Hatton, R.S., DeLaune, R.D. and Patrick, Jr., W.H. 1983. Sedimentation, accretion and subsidence in marshes of Barataria Basin, Louisiana. Limnology and Oceanography 28: 494–502.
Kjerfve and Lacerda, 1993. Mangroves of Brazil. In: Lacerda, L.D. (ed.), Conservation and sustainable utilization of mangrove forest in Latin America and Africa regions. Part I Latin America. ITTO/ International Society for Mangrove Ecosystems. Okinawa, Japan, 272 pp.
Koide, M., Soutar, A. and Goldberg, E.D. 1972. Marine geochronology with 210Pb. Earth and Planetary Science Letters 14: 442–446.
Krishnaswani, S., Benninger, L.K., Aller, R.C. and Von Damm, K.L. 1980. Atmospherically-derived radionuclides as tracers of sediment mixing and accumulation in near-shore marine and lake sediments: evidence from 7Be, 210Pb and 239,240Pu. Earth and Planetary Science Letters 47: 307–318.
Lynch, J.C., Meriwether, J.R., McKee, B.A., Vera-Herrera, F. and Twilley, R.R. 1989. Recent accretion in mangrove ecosystems based on 137Cs and 210Pb. Estuaries 4: 284–299.
McGill, J.T. 1959. Coastal classification maps, pp. 1–22. In: Russell, R.J. (ed.), Second Coastal Geography Conference, Coastal Studies Institute. Louisiana State University, Baton Rouge.
Moore, W.S. 1984. Radium isotope measurements using germanium detectors. Nuclear Instruments and Methods 223: 407–411.
Nittrouer, C.A., Sternberg, R.W., Carpenter, R. and Bennett, J.T. 1979. The use of 210Pb geochronology as a sedimentological tool: application to the Washington continental shelf. Marine Geology, 31: 297–316.
Nittrouer, C.A. and Sternberg, R.W. 1981. The formation of sedimentary strata in an allochthonous shelf environment: the Washington continental shelf. Marine Geology 42: 201–232.
Nittrouer, C.A., DeMaster, D.J., McKee, B.A., Cutshall, N.H. and Larsen, I.L. 1984. The effect of sediment mixing on 210Pb accumulation rates from the Washington continental shelf. Marine Geology 54: 201–221.
Rice, D.L. 1986. Early diagenesis in bioadvective sediments: relationships between the diagenesis of 7Be, sediment reworking rates, and the abundance of conveyor-belt deposit feeders. Journal of Marine Research 44: 149–184.
Schink, D.R. and Guinasso, N.L. 1977. Effects of bioturbation on sediment-seawater interaction. Marine Geology 23: 133–154.
Scholl, D.W., and Stuiver, M. 1967. Recent submergence of southern Florida: A comparison with adjacent coast and other eustatic data. Ecology Society of America Bulletin, 78: 437–454.
Scholl, D.W., Craighead, F.C. and Stuiver, M. 1969. Florida submergence curve revised: Its relation to coastal sedimentation rates. Science 163: 562–564.
Scoffin, T.P. 1970. The trapping and binding of subtidal carbonate sediments by marine vegetation in Bimini Lagoon, Bahamas. Journal of Sedimentary Petrology 40: 249–273.
Sharma, R., Gardner, L.R., Moore, W.S. and Bollinger, M.S. 1987. Sedimentation and bioturbation in a salt marsh as revealed by 210Pb, 137Cs and 7Be studies. Limnology and Oceanography 32: 313–326.
Smith, C.R., Pope, R.H., DeMaster, D.J. and Magaard, L. 1993. Age-dependent mixing of deep-sea sediments. Geochimica et Cosmochimica Acta 57: 1473–1488.
Spenceley, A.P. 1977. The role of pneumatophores in sedimentary processes. Marine Geology 24: M31–M37.
Spenceley, A.P. 1982. Sedimentation patterns in a mangal on Magnetic Island near Townville, North Queensland, Australia. Singapore Journal of Tropical Geography 3: 100–107.
Stevenson, J.C., Kearney, M.S. and Pendleton, E.C. 1985. Sedimentation and erosion in a Chesapeake Bay brackish marsh system. Marine Geology 67: 213–235.
Walsh, G.E. 1974. Mangroves: a review, pp. 51–174. In: Reimold, R.J. and Queen, W.H. (eds), Ecology of Halophytes. Academic Press, New York.
Woodroffe, C.D. 1981. Mangrove swamp stratigraphy and Holocene transgression, Grand Cayman Island,West Indies. Marine Geology 41: 271–294.
Woodroffe, C.D. 1990. The impact of sea-level rise on mangrove shorelines. Progress in Physical Geography 14: 483–520.
Woodroffe, C. 1992. Mangrove sediment and geomorphology, pp. 7–41. In: Robertson, A.I. and Alongi, D.M. (eds), Coastal and Estuarine Studies, Vol. 41, Tropical Mangrove Ecosystems. American Geophysical Union, Washington, DC.
Yingst, J.Y. and Rhoads, D.C. 1980. The role of bioturbation in the enhancement of microbial turnover rates in marine sediments, pp. 407–422. In: Tenore, K.R. and Coull, B.C. (eds), Marine Benthic Dynamics. University of South Carolina Press, Columbia, SC.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Smoak, J.M., Patchineelam, S.R. Sediment mixing and accumulation in a mangrove ecosystem: evidence from 210Pb, 234Th and 7Be. Mangroves and Salt Marshes 3, 17–27 (1999). https://doi.org/10.1023/A:1009979631884
Issue Date:
DOI: https://doi.org/10.1023/A:1009979631884