Effects of acid on plant litter decomposition in an arctic lake. [Carex aquatilis]
The effects of acid on the microbial decomposition of the dominant aquatic macrophyte (Carex sp.) in Toolik Lake, Alaska were studied in microcosms during the ice-free season of 1980. Toolik Lake is slightly buffered, deep, and very oligotrophic. Microbial activities, as determined by /sup 14/C-acetate incorporation into extractable lipids, associated with Carex litter were signficantly (P < 0.01) reduced within 2 days at pHs of 3.0 and 4.0, but not 5.0, 5.5 or 6.0, as compared with ambient controls (pH 7.4). ATP levels were signficantly reduced at pH 3.0 but not at the other pHs tested. After 18 days, microbial activity signficantly correlated with weight loss (P < 0.05), nitrogen content (P < 0.01), and C/N ratios (P < 0.01) of the liter, but did not correlate with ATP levels. Scanning electron microscopy of the litter surface revealed that the fungi present at ambient pH did not become domimant at pHs below 5.5, diatoms were absent below pH 4.0, and bacterial numbers and extracellular slime were greatly reduced at pH 4.0 and below. Mineralization of Carex /sup 14/C-lignin-labeled or /sup 14/C-cellulose-labeled ligno-cellulose was reduced at pH 2.0, but not at pH 4.0, 5.0, or 6.0, compared with controls (pH '). We concluded that if the pH of the water from this slightly buffered lake was sufficiently reduced, rates of litter decomposition would be significantly reduced.
- Research Organization:
- Univ. of Cincinnati, OH
- OSTI ID:
- 6928426
- Journal Information:
- Appl. Environ. Microbiol.; (United States), Journal Name: Appl. Environ. Microbiol.; (United States) Vol. 43:5; ISSN AEMID
- Country of Publication:
- United States
- Language:
- English
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Aquatic-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
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560303* -- Chemicals Metabolism & Toxicology-- Plants-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ACID RAIN
ACIDIFICATION
ALASKA
AQUATIC ECOSYSTEMS
ATMOSPHERIC PRECIPITATIONS
BIOLOGICAL EFFECTS
BIOLOGICAL MODELS
CHEMICAL REACTIONS
DECOMPOSITION
ECOSYSTEMS
ELECTRON MICROSCOPY
ENVIRONMENTAL EFFECTS
FEDERAL REGION X
INHIBITION
LAKES
MICROORGANISMS
MICROSCOPY
NORTH AMERICA
PH VALUE
POPULATION DYNAMICS
RAIN
SCANNING ELECTRON MICROSCOPY
SURFACE WATERS
USA