Effect of a lowered water table on nitrous oxide fluxes from northern peatlands

Fluctuations of water table depth (WTD) affect many processes in peatlands, such as vegetation development and emissions of greenhouse gases. Here, we present the OPtical TRApezoid Model (OPTRAM) as a new method for satellite-based monitoring of the temporal variation of WTD in peatlands. OPTRAM is based on the response of short-wave infrared reflectance to the vegetation water status. For five northern peatlands with long-term in-situ WTD records, and with diverse vegetation cover and hydrological regimes, we generate a suite of OPTRAM index time series using (a) different procedures to parametrise OPTRAM (peatland-specific manual vs. globally applicable automatic parametrisation in Google Earth Engine), and (b) different satellite input data (Landsat vs. Sentinel-2). The results based on the manual parametrisation of OPTRAM indicate a high correlation with in-situ WTD time-series for pixels with most suitable vegetation for OPTRAM application (mean Pearson correlation of 0.7 across sites), and we will present the performance differences when moving from a manual to an automatic procedure. Furthermore, for the overlap period of Landsat and Sentinel-2, which have different ranges and widths of short-wave infrared bands used for OPTRAM calculation, the impact of the satellite input data to OPTRAM will be analysed. Eventually, the challenge of merging different satellite missions in the derivation of OPTRAM time series will be explored as an important step towards a global application of OPTRAM for the monitoring of WTD dynamics in northern peatlands.

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Design of the treatment wetland determines nitrous oxide emission

10.5194/egusphere-egu21-7340 ◽

2021 ◽

Author(s):

Kuno Kasak ◽

Keit Kill ◽

Evelyn Uuemaa ◽

Ülo Mander

Keyword(s):

Nitrous Oxide ◽

Water Treatment ◽

Water Table ◽

Water Table Depth ◽

Treatment Wetlands ◽

Phosphorus Compounds ◽

Nitrogen And Phosphorus ◽

Treatment Wetland ◽

Vegetation Growth ◽

Sampling Campaign

Treatment wetlands are widespread measures to reduce agricultural diffuse pollution. Systems that are often planted with emergent macrophytes such as Typha spp. and Phragmites spp. are efficient to reduce nutrients, particularly nitrogen and phosphorus compounds. While many experiments have been conducted to study the emission of carbon dioxide (CO2) and methane (CH4), little attention has been paid for the emission of nitrous oxide (N2O). Few studies have been shown that usually N2O emission from water saturated ecosystems such as wetlands is low to negligible. In V&#228;nda in-stream treatment wetland that was built in 2015 and located in southern Estonia, we carried out first long term N2O measurements using floating chambers. The total area of the wetland is roughly .5 ha; 12 boardwalks, each equipped with two sampling spots, were created. Samples were collected biweekly from March 2019 through January 2021. In each sampling campaign water table depth, water and air temperature, O2 concentration, oxygen reduction potential, pH and electrical conductivity were registered. Water samples for TN, NO3-N, NO2-N, TOC, TIC and TC were collected from inflow and outflow of the system in each sampling session and the average concentrations were 5.1 mg/L, 3.68 mg/L, <0.1 mg/L, 41.2 mg/L and 28.7, respectively. Our results showed a very high variability of N2O emission: the fluxes ranged from -4.5 ug m-2 h-1 to 2674.2 ug m-2 h-1 with mean emission of 97.3 ug m-2 h-1. Based on gas samples (n=687) we saw a strong correlation (R2 = -0.38, p<0.0001) between N2O emission and water depth. The average N2O emission from sections with the water table depth >15 cm was 45.9 ug m-2 h-1 while sections with water table depth <15 cm showed average emission of 648.3 ug m-2 h-1. The difference between these areas was more than 10 times. Water temperature that is often considered as the main driver had less effect to the N2O emission. For instance, at lower temperatures, when the emissions from deeper zones decreased, there was no temperature effect on emissions from shallow zones. We also saw that over the years the overall N2O emission followed clear seasonal dynamics and has a slight trend towards lower emissions. This can be related to the more intensive vegetation growth that has been increased from ~40% in 2019 to approximately 90% in 2020. Our study demonstrates that the design of the wetland is not only important for the water treatment, but it can also determine the magnitude of greenhouse gas emissions. We saw that even slight changes in water table depth can have a significant effect on the annual N2O emission. Thus, in-stream treatment wetlands that have water table depth at least 15 cm likely have remarkably lower N2O emissions without losing water treatment efficiency.&#160;

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Fluxes of nitrous oxide from boreal peatlands as affected by peatland type, water table level and nitrification capacity

Biogeochemistry ◽

10.1007/bf02183033 ◽

1996 ◽

Vol 35 (3) ◽

pp. 401-418 ◽

Cited By ~ 186

Author(s):

Kristiina Regina ◽

Hannu Nykänen ◽

Jouko Silvola ◽

Pertti J. Martikainen

Keyword(s):

Nitrous Oxide ◽

Water Table ◽

Water Table Level ◽

Boreal Peatlands ◽

Type Water

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Nitrous oxide emissions as affected by fertilizer and water table management under a corn-soybean rotation

Geoderma ◽

10.1016/j.geoderma.2020.114473 ◽

2020 ◽

Vol 375 ◽

pp. 114473

Author(s):

Naeem A. Abbasi ◽

Chandra A. Madramootoo ◽

Tiequan Zhang ◽

Chin S. Tan

Keyword(s):

Nitrous Oxide ◽

Water Table ◽

Nitrous Oxide Emissions ◽

Water Table Management

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Latitudinal differentiated water table control of carbon dioxide, methane and nitrous oxide fluxes from hydromorphic soils: feedbacks to climate change

Global Change Biology ◽

10.1111/j.1365-2486.2007.01459.x ◽

2007 ◽

Vol 13 (12) ◽

pp. 2668-2683 ◽

Cited By ~ 105

Author(s):

HERMANN F. JUNGKUNST ◽

SABINE FIEDLER

Keyword(s):

Climate Change ◽

Carbon Dioxide ◽

Nitrous Oxide ◽

Water Table ◽

Hydromorphic Soils ◽

Water Table Control

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Patterned fens of western Labrador and adjacent Quebec: phytosociology, water chemistry, landform features, and dynamics of surface patterns

Canadian Journal of Botany ◽

10.1139/b88-327 ◽

1988 ◽

Vol 66 (12) ◽

pp. 2402-2418 ◽

Cited By ~ 21

Author(s):

David R. Foster ◽

George A. King ◽

Mary V. Santelmann

Keyword(s):

Water Chemistry ◽

Water Table ◽

Vegetation Type ◽

Open Water ◽

Differential Rate ◽

Peat Accumulation ◽

Surface Patterns ◽

Vegetation Water ◽

Northern Peatlands ◽

Pool Formation

The landforms, vegetation, water chemistry, and stratigraphy of four patterned fens (aapamires) in western Labrador and adjacent Quebec are described in a study investigating the origin and characteristics of surface patterns on northern peatlands. Phytosociological analysis by the relevé approach, in conjunction with analysis by TWINSPAN, is used to describe 11 floristic noda. The vegetational patterns are largely controlled by depth to the water table. Mire landforms discussed in detail include ice-push ridges, flarks and pools, peat ridges, and mire-margin hummocks. Water chemistry is typical of minerotrophic conditions, with pH ranging from 4.4 to 6.7 and calcium concentrations from 20 to 430 μiequiv. L−1. The water chemistry, vegetation, and landforms on the mires are compared with other studies from Labrador and circumboreal regions. Stratigraphic results and field observations support the theory that surface patterns on the mire develop slowly through the interplay of biological and hydrological processes, specifically differential rate of peat accumulation controlled by vegetation type and depth to water table. Pool formation apparently involves four steps: (i) gradual differentiation of shallow flarks on previously undifferentiated mire surface; (ii) expansion and deepening of flarks and development of ridges due to differential peat accumulation; (iii) degradation of flark vegetation into mud bottoms and open-water pools; and (iv) coalescence, continued expansion, and deepening of open-water areas. Hydrological controls over the rate and extent of pool formation are discussed as a probable explanation of the geographical distribution of patterned mires.

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Water Table Fluctuation in Peatlands Facilitates Fungal Proliferation, Impedes Sphagnum Growth and Accelerates Decomposition

Frontiers in Earth Science ◽

10.3389/feart.2020.579329 ◽

2021 ◽

Vol 8 ◽

Author(s):

Jinhyun Kim ◽

Line Rochefort ◽

Sandrine Hogue-Hugron ◽

Zuhair Alqulaiti ◽

Christian Dunn ◽

...

Keyword(s):

Organic Matter ◽

Microbial Community ◽

Water Table ◽

High Frequency ◽

Organic Matter Decomposition ◽

Anaerobic Conditions ◽

Water Table Fluctuation ◽

Decomposition Of Organic Matter ◽

Northern Peatlands ◽

Low Rate

Northern peatlands are substantial carbon sinks because organic matter in peat is highly stable due to the low rate of decomposition. Waterlogged anaerobic conditions induce accumulation of Sphagnum-derived phenolic compounds that inhibit peat organic matter decomposition, a mechanism referred to as the “enzymic latch”. Recent studies have predicted that the water table in northern peatlands may become unstable. We observed that such unstable water table levels can impede the development of Sphagnum mosses. In this study, we determined the effects of low and high frequency water table fluctuation regimes on Sphagnum growth and peat organic matter decomposition, by conducting a year-long mesocosm experiment. In addition, we conducted a molecular analysis to examine changes in abundance of fungal community which may play a key role in the decomposition of organic matter in peatlands. We found that rapid water table fluctuation inhibited the growth of Sphagnum due to fungal infection but stimulated decomposition of organic matter that may dramatically destabilize peatland carbon storage. Increased pH, induced by the fluctuation, may contribute to the enhanced activity of hydrolases in peat. We demonstrated that the water table fluctuation in peatlands impeded Sphagnum growth and accelerates decomposition due to fungal proliferation. Thus, we suggested that understanding the microbial community in the northern peatlands is essential for elucidating the possible changes in carbon cycle of peatland under the changing world.

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A study of mole drainage with simplified cultivation for autumn-sown crops on a clay soil

The Journal of Agricultural Science ◽

10.1017/s0021859600042118 ◽

1984 ◽

Vol 102 (3) ◽

pp. 561-581 ◽

Cited By ~ 59

Author(s):

G. L. Harris ◽

M. J. Goss ◽

R. J. Dowdell ◽

K. R. Howse ◽

P. Morgan

Keyword(s):

Nitrous Oxide ◽

Water Table ◽

Clay Soil ◽

Drainage System ◽

Drainage Water ◽

Surface Flow ◽

Deep Drainage ◽

Winter Rainfall ◽

Nitrate N ◽

Plough Layer

SummaryThe soil water regimes, flow paths of water and concentrations of nutrients in this water were measured for a clay soil growing winter wheat in 1978–9 and 1979–80. The soil was either drained with mole drains at 2 m spacing connected to plot drains 46 m apart or undrained. In the 1st year a compacted layer at about 20 cm depth caused a perched water table in the Ap horizon in both drainage treatments, and prevented the mole drains at 60 cm from affecting the water table. In 1979–80 after cultivation to disrupt the compacted layer, midway between the mole drains the depth to the winter water table was 20 cm greater than in undrained soil.Surface flow, interflow at the depth of the plough layer and deep drainflow from mole and pipe drains responded rapidly to winter rainfall events. During both winters the mole and tile system removed most of the rainfall on the drained plots and the peaky hydrographs were typical of a mole system in a clay soil. In the undrained plots only a small proportion of the winter rainfall was accounted for in flow from the top 30 cm, and up to 75% of the water was able to percolate downwards possibly to below the barriers that separated the plots. Long-term water-balance studies indicated that a proportion of the water moving to depth in the undrained plots was probably entering the deep drainage system of the drained plots. As a result, the mole and pipe drainage system often removed more water than the rainfall input less evapotranspiration. This problem did not affect the depth to the water tables.For each flow component concentrations of nitrate, ammonium, nitrous oxide, phosphorus, potassium and calcium were measured in the drainage water. Concentrations of nitrate-N from all drained plots were largest in autumn, being in the range 50–95 mg N/1, but then decreased to 1–5 mg N/1 by the end of March. Losses of nitrate-N were mainly through the mole drains and amounted to 43·6 and 59·7 kg N/ha in the 2 years. The quantities of nitrate-N lost in surface runoff or in flow in the cultivated layer were small on both treatments. Gaseous nitrous oxide, ammonium and phosphorus contents were very small. Potassium concentrations were somewhat larger, but not exceeding 3·5 mg/1. The calcium concentrations were in the range 40–210 mg/1. Concentrations of herbicides measured in November 1980 were negligible.In the 2nd year water was taken up from a greater depth in the drained than in the undrained plots from April onwards. These results are discussed in relation to water supply to the crops at this site.

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The effect of forestry drainage practices on the emission of methane from northern peatlands

Canadian Journal of Forest Research ◽

10.1139/x95-055 ◽

1995 ◽

Vol 25 (3) ◽

pp. 491-499 ◽

Cited By ~ 52

Author(s):

Nigel T. Roulet ◽

T. R. Moore

Keyword(s):

Water Table ◽

Drainage Ditches ◽

Flux Data ◽

Northern Peatlands ◽

Forested Bog ◽

The Impact ◽

Forest Drainage

Methane (CH4) flux was measured from undrained, drained, and ditched portions of treed fen, forested bog, and treed bog sites in the Wally Creek experimental drainage site (near Cochrane, Ontario), from May to October 1991. Drainage for 7 years lowered the water table from between −21 and −49 cm to −41 and −93 cm at the three respective sites. Drainage resulted in a conversion of the peatlands from a CH4 source (0 to 15 mg CH4 •m−2 •d−1) to a small CH4 sink (0 to −0.4 mg CH4 •m−2 •d−1). In contrast, CH4 efflux from the ditches ranged from <5 to >400 mg CH4 m−2 •d−1. The flux data were used to estimate the impact of forest drainage practices on net CH4 emissions from a forest drainage complex. For the treed and forested bogs, there was a net increase in CH4 emissions where ditch spacing was closer than 38 m. Even with very close ditch spacing (>12 m), there was a net decrease in CH4 flux from the treed fen. The results of this study indicate that the combination of low antecedent CH4 fluxes from an undrained peatland, and moderate fluxes from the drainage ditches, will produce a net increase in CH4 emissions from forest drainage.

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