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Acidification of the HUMEX Lake; Effects on epilimnetic pools and fluxes of carbon
AbstractThe paper presents data on carbon budgets during the first year of acidification of one half of humic lake Skjervatjern. Dissolved organic carbon (DOC), mainly allochthonous humus, ranged from 2 to 12 mg C L−1, with an average of 6 to 7 mg C for both the acidified and the reference basin. The minimum values occurred during winter when ground temperature fell below zero. Average dissolved inorganic carbon (DIC) was near 500 μg C L−1 in the surface layers, but increased to more than 2 mg close to the bottom. Epilimnetic particulate organic carbon (POC) was also close to 500 μg C L−1, of which more than 3/4 was detritus, while bacteria, phyto-, and macrozooplankton made up approximately 100, 50, and 20–40 μg C L−1, respectively. Major flows were sedimentation, respiration, and discharge. Acidification gave no clearcut effects on the major pools and fluxes of carbon, which were mainly governed by climatic and hydrological events. There were, however, pronounced differences in biotic pools and biologically mediated carbon fluxes, with more unstable conditions in the acidified basin. Primary production and phytoplankton biomass increased in the acidified basin relative to the control. Zooplankton biomass had a strong midsummer peak, followed by a sudden collapse of the dominant species, Holopedium gibberum, in the acidified part. As a consequence, zooplankton community grazing also dropped. Grazing did, however, not exert an efficient control with phytoplankton biomass. Preliminary data indicated decreased respiration and increased sedimentation in the acidified part. A closer follow-up of these processes will be performed during the two upcoming years in order to separate transitional and more permanent changes in carbon metabolism.
Acidification of the HUMEX Lake; Effects on epilimnetic pools and fluxes of carbon
AbstractThe paper presents data on carbon budgets during the first year of acidification of one half of humic lake Skjervatjern. Dissolved organic carbon (DOC), mainly allochthonous humus, ranged from 2 to 12 mg C L−1, with an average of 6 to 7 mg C for both the acidified and the reference basin. The minimum values occurred during winter when ground temperature fell below zero. Average dissolved inorganic carbon (DIC) was near 500 μg C L−1 in the surface layers, but increased to more than 2 mg close to the bottom. Epilimnetic particulate organic carbon (POC) was also close to 500 μg C L−1, of which more than 3/4 was detritus, while bacteria, phyto-, and macrozooplankton made up approximately 100, 50, and 20–40 μg C L−1, respectively. Major flows were sedimentation, respiration, and discharge. Acidification gave no clearcut effects on the major pools and fluxes of carbon, which were mainly governed by climatic and hydrological events. There were, however, pronounced differences in biotic pools and biologically mediated carbon fluxes, with more unstable conditions in the acidified basin. Primary production and phytoplankton biomass increased in the acidified basin relative to the control. Zooplankton biomass had a strong midsummer peak, followed by a sudden collapse of the dominant species, Holopedium gibberum, in the acidified part. As a consequence, zooplankton community grazing also dropped. Grazing did, however, not exert an efficient control with phytoplankton biomass. Preliminary data indicated decreased respiration and increased sedimentation in the acidified part. A closer follow-up of these processes will be performed during the two upcoming years in order to separate transitional and more permanent changes in carbon metabolism.
Acidification of the HUMEX Lake; Effects on epilimnetic pools and fluxes of carbon
Hessen, Dag O. (author)
Environmental International ; 18 ; 649-657
1992-09-02
9 pages
Article (Journal)
Electronic Resource
English
HUMEX (humic lake acidification experiment): chemistry, hydrology, and meteorology
| Online Contents | 1994