Water, salt and nutrient fluxes of tropical tidal salt flats
Tóm tắt
The water budget of a tropical tidal salt flat in dry tropical Australia has been studied with particular emphasis on estimating the groundwater fluxes. Salt was used as a passive tracer to determine some of these fluxes. Groundwater salt accumulation (or loss) was less than 1 kg/m3/month. Surface water leaving the flat at a higher salt concentration than flood water causes a net outwelling of salt of between 0.4 and 1 kg/m2/month. Evaporation from the salt flat was estimated to be 70 mm/month. Using these measurements and a simple model of the groundwater flows, it is concluded that the groundwater loss is less than 40 mm/month. The accuracy of the salt budget was insufficient to rule out the possibility that the net groundwater motion was upwards. Measurements of Si and PO_4 fluxes indicated that the net outwelling due to surface water flows were respectively 3 mmole/m2/month and 0.014 mmole/m2/month. A net groundwater loss of 10 mm would produce a similar magnitude outwelling due to groundwater discharge. The mangrove-fringed tropical tidal salt flats are the source of large quantities of nutrients that are released to the near-shore zone.
Tài liệu tham khảo
Arya, S.P.S. 1988. Introduction to Micrometeorology. Academic Press, San Diego.
Dauphinee, T.M. 1980. Introduction to the special issue on the practical salinity scale 1978. IEEE Journal of Oceanic Engineering OE-5(1): 1–21.
Dowling, R.M. and MacDonald, T.J. 1982. Mangrove communities of Queensland. pp. 79–93. In: Clough, B.F. (ed.), Mangrove Ecosystems in Australia, pp. 79–93. Australian National University Press, Canberra.
Hollins, S. 1996. Evaporation over a tropical tidal salt flat. Honours Thesis, Physics Department, James Cook University, 77 pp
Hollins, S. and Ridd, P.V. 1997. Evaporation over a tropical tidal salt flat. Mangroves and Salt Marshes 1: 95–102.
Rhodes, E.G. 1980. Modes of Holocene coastal progradation: Gulf of Carpentaria. Ph.D. Thesis, Department of Biogeography and Geomorphology, Australian National University, 203 pp.
Ridd., P.V., Sandstrom, M.W. and Wolanski, E. 1988. Outwelling from tropical tidal salt flats. Estuarine Coastal and Shelf Science 26: 243–253.
Ridd, P.V. and Sam, R. 1996. Profiling groundwater salt concentrations in mangrove swamps and tropical salt flats. Estuarine Coastal and Self Science 43: 627–635.
Semeniuk, V. 1983. Mangrove distribution in Northwestern Australia in relationship to regional and local freshwater seepage. Vegetatio 53: 11–31.
Weast, R.C. 1969. CRC Handbook of Chemistry and Physics, p. D258, Chemical Rubber Company, Boca Raton, Florida.
Wilson, E.M. 1990. pp. 87–89. Engineering Hydrology, Macmillan, London.