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Temporal Patterns of Methane Emissions From Two Streams With Different Riparian Connectivity
Author(s) -
Leng Peifang,
Kamjunke Norbert,
Li Fadong,
Koschorreck Matthias
Publication year - 2021
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1029/2020jg006104
Subject(s) - streams , riparian zone , environmental science , soil water , methane , hydrology (agriculture) , ecology , soil science , geology , computer network , geotechnical engineering , habitat , computer science , biology
Streams are regionally important sources of CH 4 to the atmosphere, but the temporal variability in and control on CH 4 concentrations and emissions are not well understood. Especially, lack of long‐term data hampers our ability to predict CH 4 emissions from streams. Here, we present a 7‐year data set of biweekly CH 4 concentration and underlying potential drivers from two adjacent small German streams with contrasting riparian area characteristics. Over the 7‐year study period, mean CH 4 concentration and emissions were 0.20 and 0.07 μmol L −1 and 2.01 and 0.84 mmol m −2 d −1 for the two streams, respectively. Our findings suggest that the combination of seasonality and topography ultimately shaped the considerable temporal variations of CH 4 . CH 4 oxidation and production in the streams were probably of minor importance. Instead, fluctuations in CH 4 concentrations likely reflected a temporal pattern of CH 4 input from soils of the riparian zone with larger CH 4 variations in the stream with more riparian lands. Structural equation modeling revealed dissolved organic carbon and nitrate as important predictors of CH 4 concentration. However, we did not identify predictors of the considerable short‐term variability, nor the explicit pathways of CH 4 delivery to streams. The discrepancy of the CH 4 flux between streams was likely triggered by different connectivities to riparian soils with higher CH 4 emissions in the hydrologically more connected stream. Interannual comparison showed that changing hydrologic conditions, rather than warming, may impact future CH 4 emissions from temperate streams. We predict that higher CH 4 emissions occur in wetter years in streams with close connectivity to riparian soils.