Seasonal distribution of methane flux in a Minnesota peatland measured by eddy correlation
Seasonal distribution of methane flux in a Minnesota peatland measured by eddy correlation
复制标题
通过涡相关测量明尼苏达州泥炭地甲烷通量的季节分布
DOI：
10.1029/93jd02181
复制
发表时间：
1993
影响因子：
--
通讯作者：
D. Billesbach
中科院分区：
文献类型：
--
作者：
N. Shurpali;S. Verma;R. Clement;D. Billesbach
Methane flux was measured using the micrometerological eddy correlation technique during 62 days in mid-May through mid-October 1991 in a peatland ecosystem in north central Minnesota. Application of this technique allows measurement of spatially integrated fluxes. The distribution of methane flux consisted of a gradual pattern with several episodic emissions superimposed. The gradual (nonepisodic) pattern of methane flux (daytime average) exhibited an increase from 30-120 mg m{sup {minus}2}/d in late May to early July to 125-160 mg m{sup {minus}2}/d in mid-July to mid-August and then a decline to 100-35 mg m{sup {minus}2}/d in early September to mid-October. Peat temperature (at 0.1 m depth) and water table depth accounted for about 70% of the variance in the methane flux data. The episodic emissions were associated with drops in atmospheric pressure and a declining water table. Generally, the hourly values of daytime methane flux were fairly stable, perhaps with a slight depression during the midday. However, on days with episodic emissions, the daytime methane flux had a peak during the midafternoon, and its pattern appeared to be similar to those of the standard deviation of atmospheric pressure flunctuations and mean horizontal wind velocity. The ratio of soil CO{sub 2} to methane fluxesmore » (during nonepisodic emission periods) increased with increasing water table depth in a manner similar to that observed in a laboratory study of peat columns from different wetland types in Quebec. The annual methane emission for this ecosystem was estimated to be about 16-19.5 gm{sup {minus}2}yr{sup {minus}1}. 29 refs., 7 figs., 2 tabs.« less
Methane flux was measured using the micrometerological eddy correlation technique during 62 days in mid-May through mid-October 1991 in a peatland ecosystem in north central Minnesota. Application of this technique allows measurement of spatially integrated fluxes. The distribution of methane flux consisted of a gradual pattern with several episodic emissions superimposed. The gradual (nonepisodic) pattern of methane flux (daytime average) exhibited an increase from 30-120 mg m{sup {minus}2}/d in late May to early July to 125-160 mg m{sup {minus}2}/d in mid-July to mid-August and then a decline to 100-35 mg m{sup {minus}2}/d in early September to mid-October. Peat temperature (at 0.1 m depth) and water table depth accounted for about 70% of the variance in the methane flux data. The episodic emissions were associated with drops in atmospheric pressure and a declining water table. Generally, the hourly values of daytime methane flux were fairly stable, perhaps with a slight depression during the midday. However, on days with episodic emissions, the daytime methane flux had a peak during the midafternoon, and its pattern appeared to be similar to those of the standard deviation of atmospheric pressure flunctuations and mean horizontal wind velocity. The ratio of soil CO{sub 2} to methane fluxesmore » (during nonepisodic emission periods) increased with increasing water table depth in a manner similar to that observed in a laboratory study of peat columns from different wetland types in Quebec. The annual methane emission for this ecosystem was estimated to be about 16-19.5 gm{sup {minus}2}yr{sup {minus}1}. 29 refs., 7 figs., 2 tabs.« less