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Methane production and oxidation in lakes impacted by the May 18, 1980 Eruption of Mount St. Helens
Author(s) -
Lilley Marvin D.,
Baross John A.,
Dahm Clifford N.
Publication year - 1988
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/gb002i004p00357
Subject(s) - anoxic waters , flux (metallurgy) , geology , hydrology (agriculture) , methane , anaerobic oxidation of methane , oceanography , environmental chemistry , environmental science , chemistry , ecology , biology , geotechnical engineering , organic chemistry
The concentrations of CH 4 and CH 4 oxidation rates were measured in lakes impacted by the May 18, 1980 eruption of Mount St. Helens. The highest CH 4 concentrations were recorded during the first summer after the eruption and ranged in surface waters from 5 μM in the moderately impacted Ryan Lake to 28 μM in the heavily impacted North Coldwater Lake. At depths below the oxic/anoxic interface, CH 4 levels reached 250 μM in North Coldwater Lake, 184 μM in Spirit Lake, 70 μM in Castle Creek Lake, and 60 μM in Ryan Lake. The CH 4 flux measurements from these lakes during the summer following the May 18, 1980 eruption were the highest ever recorded in lakes with ranges of 1.1–2.9 mmol CH 4 m −2 d −1 in the light to moderately impacted McBride and Ryan Lakes to ranges of 17.4–25.3 mmol CH 4 m −2 d −1 in the heavily impacted Castle Creek, North Coldwater, and Spirit Lakes. Evidence of CH 4 oxidation was seen in all of the lakes during the summer of 1981, and rates of CH 4 oxidation using 14 C‐CH 4 were measured in Spirit Lake from 1982 to 1986. The highest rates of CH 4 oxidation measured were during the summer stratification and ranged from 50 to 150 nmol CH 4 oxidized L −1 d −1 . Methane oxidation rates were measured in waters having oxygen concentrations less than 100 μM with highest activity occurring at concentrations of 30–60 μM. Spirit Lake samples taken during 1986 showed a marked reduction in the levels of CH 4 . This has corresponded with a marked reduction in the levels of dissolved organic material in the lake and an apparent decline in sedimentary methanogenesis. The lakes heavily impacted by the eruption of Mount St. Helens, while having gone through a 2–3 year period of eutrophy following the massive input of organic wood debris and inorganic nutrients associated with ash and pyroclastic materials, are presently rapidly returning to preeruption conditions characteristic of oligotrophic, subalpine lakes.