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.

Parent Lithology, Surface-Groundwater Exchange, and Nitrate Retention in Headwater Streams

H. Maurice Valett, John A. Morrice, Clifford N. Dahm and Michael E. Campana
Limnology and Oceanography
Vol. 41, No. 2 (Mar., 1996), pp. 333-345
Stable URL: http://www.jstor.org/stable/2838760
Page Count: 13
  • More info
  • Cite this Item
Parent Lithology, Surface-Groundwater Exchange, and Nitrate Retention in Headwater Streams
Preview not available

Abstract

We address the ecological ramifications of variation in hydrologic interaction between streams and alluvial aquifers in catchments with alluvium derived from parent materials of contrasting geologic composition. We present a conceptual model in which solute retention in streams results from hydrologic retention (increased water residence time resulting from surface-groundwater exchange), biological nutrient cycling, and chemical processes. Solute injection experiments were done in study catchments comprised of sandstone siltstone (site 1), volcanic tuff (site 2), and granite-gneiss (site 3). Distribution of an injected conservative tracer (Br) illustrated that rate and extent of surface-water penetration into the alluvial aquifer increased across study catchments as was predicted from increasing alluvial hydraulic conductivity. Concurrently, groundwater inputs at baseflow represented between 13 and 57% of aboveground discharge at upstream transects, indicating bidirectional hydrologic exchange along the study reaches. N:P ratios in surface water ranged from 4 to 16, suggesting strong biotic demand for inorganic N. Coinjection of NaBr and NaNO3 revealed longest nitrate uptake length (Sw) at site 1, and shortest uptake length at site 3. Modeling of transient hydrologic solute storage revealed that Sw correlated with hydraulic storage, suggesting an important role for subsurface processes in total nitrate retention.

Page Thumbnails

  • Thumbnail: Page 
333
    333
  • Thumbnail: Page 
334
    334
  • Thumbnail: Page 
335
    335
  • Thumbnail: Page 
336
    336
  • Thumbnail: Page 
337
    337
  • Thumbnail: Page 
338
    338
  • Thumbnail: Page 
339
    339
  • Thumbnail: Page 
340
    340
  • Thumbnail: Page 
341
    341
  • Thumbnail: Page 
342
    342
  • Thumbnail: Page 
343
    343
  • Thumbnail: Page 
344
    344
  • Thumbnail: Page 
345
    345