Dissolved organic matter and lake metabolism: Biogeochemistry and controls of nutrient flux dynamics in lakes: Technical progress report, 1 July 1987--30 June 1988

Technical Report · Fri Jan 01 04:00:00 EST 1988

OSTI ID:7078919

Wetzel, R G

Our work has continued and expanded in the region of nutrient fluxes, uptake mechanisms, and recycling in microcommunities on the plants and within the plants. Limiting nutrient factors are dissolved inorganic carbon, phosphorus, and in some cases, nitrogen. The macrophyte-epiphyte complex exists in a viscous medium where regions of greatly reduced flow and no turbulence occur at surfaces. As a result of the greatly reduced flow, lack of turbulence,and extremely slow rate of diffusion in water, diffusional processes predominate within the boundary layer. During periods of high metabolic activity (i.e., during photosynthesis) nutrients are likely to become depleted within the boundary layer, constraining production and placing the macrophyte and associated microflora in direct nutrient competition. Once nutrients have entered the complex via diffusion or sedimentation from the bulk phase, or uptake through the macrophyte rhizosphere, exit across the boundary layer is retarded. The close juxtaposition of the biota results in a rapid cycling and, ultimately, in concentration of nutrients. This occurs until the end of the macrophyte vegetative life span when the supporting macrophyte loses its integrity and release of dissolved matter exceeds the retentive capacity of the microbiota. A quantity of this material released by the macrophyte is retained in the epiphyton when the macrophyte-epiphyte complex sinks to the sediment. 324 refs., 6 figs.

• Research Organization: Michigan Univ., Ann Arbor (USA). Dept. of Biology
• DOE Contract Number: FG02-87ER60515
• OSTI ID: 7078919
• Report Number(s): DOE/ER/60515-2-Pt.1; COO-1599-323-Pt.1; ON: DE88016540
• Country of Publication: United States
• Language: English

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