Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

Littoral-Pelagic Phosphorus Dynamics During Nighttime Convective Circulation

William F. James and John W. Barko
Limnology and Oceanography
Vol. 36, No. 5 (Jul., 1991), pp. 949-960
Stable URL: http://www.jstor.org/stable/2837591
Page Count: 12
  • More info
  • Cite this Item
Littoral-Pelagic Phosphorus Dynamics During Nighttime Convective Circulation
Preview not available

Abstract

Littoral phosphorus dynamics and P exchanges between littoral and pelagic zones, driven by nighttime convective circulation, were examined in Eau Galle Reservoir, Wisconsin, during summer 1989. Rates of P release from littoral sediments, measured in laboratory incubation systems, increased linearly with pH under both aerobic and anaerobic conditions. Estimated rates of P release from littoral sediments, based on field measurements of pH and oxygen, averaged $3.6 mg m^-2 d^-1$ under aerobic conditions and were in close agreement with independently determined diffusional fluxes across the littoral-sediment interface. Marked vertical gradients in P developed during summer in bottom waters of the littoral zone. The littoral zone cooled more rapidly at night than the pelagic zone on 72% of midsummer days (June-August), promoting nighttime convective circulation. On the basis of patterns of dye dispersion during these periods of circulation, cooler littoral bottom water moved into the pelagic zone as an interflow confined to the base of the epilimnion, while pelagic water moved into the littoral zone as a surface flow. Hourly volumetric flow rates were linearly related to mean negative horizontal temperature gradients that developed at night. Net total P flux from the littoral to the pelagic zone ranged from 0.12 to $0.43 mg m^-2 h^-1$ (avg. 0.22) for the summer. Nighttime convective circulation seems to be an important mechanism for movement of littoral P to the pelagic zone in this reservoir.

Page Thumbnails

  • Thumbnail: Page 
949
    949
  • Thumbnail: Page 
950
    950
  • Thumbnail: Page 
951
    951
  • Thumbnail: Page 
952
    952
  • Thumbnail: Page 
953
    953
  • Thumbnail: Page 
954
    954
  • Thumbnail: Page 
955
    955
  • Thumbnail: Page 
956
    956
  • Thumbnail: Page 
957
    957
  • Thumbnail: Page 
958
    958
  • Thumbnail: Page 
959
    959
  • Thumbnail: Page 
960
    960