Effects of nitrate and sulfate on greenhouse gas emission potentials from microform-derived peats of a boreal peatland: A 13C tracer study

Lozanovska, Ivana; Kuzyakov, Yakov; Krohn, Johannes; Parvin, Shahnaj; Dorodnikov, Maxim

doi:10.1016/j.soilbio.2016.06.018

Cited by 26 publications

(9 citation statements)

References 38 publications

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“…No indications for anammox were found in this bog, probably as a result of the fast conversion of NO 3 − by denitrification and/or DNRA. Potential denitrification consisted mostly of N 2 O (Table 2b), consistent with the relatively low pH of the peat soil (Simek and Cooper, 2002;Van den Heuvel et al, 2011) and this corresponds with the finding that Nox increases gaseous N emissions, especially of N 2 O (Lozanovska et al, 2016;Roobroeck et al, 2010). This is important because N 2 O is the third most important contributor to global warming (Forster et al, 2007).…”

Section: N Losses To the Atmospheresupporting

confidence: 77%

Effects of airborne ammonium and nitrate pollution strongly differ in peat bogs, but symbiotic nitrogen fixation remains unaffected

Elzen

Berg²,

Weijden

et al. 2018

Science of The Total Environment

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Pristine bogs, peatlands in which vegetation is exclusively fed by rainwater (ombrotrophic), typically have a low atmospheric deposition of reactive nitrogen (N) (<0.5kghay). An important additional N source is N fixation by symbiotic microorganisms (diazotrophs) in peat and mosses. Although the effects of increased total airborne N by anthropogenic emissions on bog vegetation are well documented, the important question remains how different N forms (ammonium, NH, versus nitrate, NO) affect N cycling, as their relative contribution to the total load strongly varies among regions globally. Here, we studied the effects of 11years of experimentally increased deposition (32 versus 8kgNhay) of either NH or NO on N accumulation in three moss and one lichen species (Sphagnum capillifolium, S. papillosum, Pleurozium schreberi and Cladonia portentosa), N fixation rates of their symbionts, and potential N losses to peat soil and atmosphere, in a bog in Scotland. Increased input of both N forms led to 15-90% increase in N content for all moss species, without affecting their cover. The keystone species S. capillifolium showed 4 times higher N allocation into free amino acids, indicating N stress, but only in response to increased NH. In contrast, NO addition resulted in enhanced peat N mineralization linked to microbial NO reduction, increasing soil pH, N concentrations and N losses via denitrification. Unexpectedly, increased deposition from 8 to 32kghay in both N forms did not affect N fixation rates for any of the moss species and corresponded to an additional input of 5kgNhay with a 100% S. capillifolium cover. Since both N forms clearly show differential effects on living Sphagnum and biogeochemical processes in the underlying peat, N form should be included in the assessment of the effects of N pollution on peatlands.

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Section: N Losses To the Atmospheresupporting

confidence: 77%

Effects of airborne ammonium and nitrate pollution strongly differ in peat bogs, but symbiotic nitrogen fixation remains unaffected

Elzen

Berg²,

Weijden

et al. 2018

Science of The Total Environment

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“…Likewise, Weyhenmeyer et al [2015b] showed that direct inputs of DIC from the terrestrial surroundings of a lake have a stronger influence on CO 2 concentrations in lake water than do lake internal CO 2 production. As precipitation and runoff have shown an overall increase across Sweden over the past few decades, in particular during the 1990s and 2000s [Bengtsson and Rana, 2014;Lindström and Bergström, 2004;Weyhenmeyer et al, 2014Weyhenmeyer et al, , 2015a, we suggest that most waters now receive proportionally more shallow groundwater compared to deep groundwater [Laudon et al, 2007] (Figure 5). Such an increase most likely results in a DOC concentration increase in surface waters as DOC concentration in soil profiles tends to increase toward the top soil layers [Grabs et al, 2012;Kaiser and Kalbitz, 2012].…”

Section: Discussionmentioning

confidence: 87%

“…They suggested that DOC and p CO 2 can covary due to recovery from acidification. Both DOC and p CO 2 are highly sensitive to acidification‐induced changes in ionic strength of soils [ Evans et al ., ; Lozanovska et al ., ]. In Sweden, recovery from acidification is also apparent, seen by decreasing SO 4 2− concentrations in waters [ Weyhenmeyer , ] and increasing alkalinity [ Futter et al ., ].…”

Section: Introductionmentioning

confidence: 99%

No long‐term trends in pCO₂ despite increasing organic carbon concentrations in boreal lakes, streams, and rivers

Nydahl

Wallin

Weyhenmeyer

2017

Global Biogeochemical Cycles

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Concentrations of dissolved organic carbon (DOC) from terrestrial sources have been increasing in freshwaters across large parts of the boreal region. According to results from large‐scale field and detailed laboratory studies, such a DOC increase could potentially stimulate carbon dioxide (CO2) production, subsequently increasing the partial pressure of CO2 (pCO2) in freshwaters. However, the response of pCO2 to the presently observed long‐term increase in DOC in freshwaters is still unknown. Here we tested whether the commonly found spatial DOC‐pCO2 relationship is also valid on a temporal scale. Analyzing time series of water chemical data from 71 lakes, 30 streams, and 4 river mouths distributed across all of Sweden over a 17 year period, we observed significant DOC concentration increases in 39 lakes, 15 streams, and 4 river mouths. Significant pCO2 increases were, however, only observed in six of these 58 waters, indicating that long‐term DOC increases in Swedish waters are disconnected from temporal pCO2 trends. We suggest that the uncoupling of trends in DOC concentration and pCO2 are a result of increased surface water runoff. When surface water runoff increases, there is likely less CO2 relative to DOC imported from soils into waters due to a changed balance between surface and groundwater flow. Additionally, increased surface water runoff causes faster water flushing through the landscape giving less time for in situ CO2 production in freshwaters. We conclude that pCO2 is presently not following DOC concentration trends, which has important implications for modeling future CO2 emissions from boreal waters.

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“…This has been found in other pocosin wetland soils on the coast of North Carolina (Ardón et al 2018). Variable effects of salinity (and or sulfate additions) have been found on soil respiration, with some studies showing an increase (Marton et al, 2012;Weston et al, 2011), a decrease (Lozanovska et al 2016;Servais et al 2019), or no change (Baldwin et al, 2006). Krauss et al (2012) found that permanently flooded saltwater treatments (expected in non-tidal wetlands) in a simulated coastal swamp mesocosm reduced soil respiration, whereas saltwater pulses (expected in tidal wetlands) had a variable effect on soil respiration.…”

Section: Discussionmentioning

confidence: 70%

Saltwater reduces CO2 and CH4 production in organic soils from a coastal freshwater forested wetland

Minick

Mitra

Noormets

et al. 2019

Preprint

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Abstract. A major concern for coastal freshwater wetland function and health is saltwater intrusion and the potential impacts on greenhouse gas production. Coastal freshwater wetlands are likely to experience increased hydroperiod with rising sea level, as well as saltwater intrusion. These potential changes to wetland hydrology may also alter forest structure and lead to a transition from forest to shrub/marsh wetland ecosystems. Loss of forested wetlands is already evident by dying trees and dead standing trees (&quot;ghost&quot; forests) along the Atlantic Coast of the US, which will result in significant alterations to plant carbon (C) inputs, particularly that of coarse woody debris, to soils. We investigated the effects of salinity and wood C inputs on soils collected from a coastal freshwater forested wetland in North Carolina, USA, and incubated in the laboratory with either freshwater or saltwater (2.5 or 5.0&#8201;ppt) and with or without the additions of wood. Saltwater additions at 2.5&#8201;ppt and 5.0 &#8201;ppt reduced CO2 production by 41 and 37&#8201;%, respectively, compared to freshwater. Methane production was reduced by 98&#8201;% (wood-free incubations) and by 75&#8211;87&#8201;% (wood-amended incubations) in saltwater treatments compared to the freshwater treatment. Additions of wood resulted in lower CH4 production from the freshwater treatment and higher CH4 production from saltwater treatments compared to wood-free incubations. The &#948;13CH4-C isotopic signature indicated that in wood-free incubations, CH4 produced from the freshwater treatment was from the acetoclastic pathway, while CH4 produced from the saltwater treatments was more likely from the hydrogenotrophic pathway. These results suggest that saltwater intrusion into subtropical coastal freshwater forested wetlands will reduce CH4 fluxes, but long-term changes in C dynamics will likely depend on how changes in wetland vegetation and microbial function influences C inputs to the soil.

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Effects of nitrate and sulfate on greenhouse gas emission potentials from microform-derived peats of a boreal peatland: A 13C tracer study

Cited by 26 publications

References 38 publications

Effects of airborne ammonium and nitrate pollution strongly differ in peat bogs, but symbiotic nitrogen fixation remains unaffected

Effects of airborne ammonium and nitrate pollution strongly differ in peat bogs, but symbiotic nitrogen fixation remains unaffected

No long‐term trends in pCO₂ despite increasing organic carbon concentrations in boreal lakes, streams, and rivers

Saltwater reduces CO<sub>2</sub> and CH<sub>4</sub> production in organic soils from a coastal freshwater forested wetland

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Effects of nitrate and sulfate on greenhouse gas emission potentials from microform-derived peats of a boreal peatland: A 13C tracer study

Cited by 26 publications

References 38 publications

Effects of airborne ammonium and nitrate pollution strongly differ in peat bogs, but symbiotic nitrogen fixation remains unaffected

Effects of airborne ammonium and nitrate pollution strongly differ in peat bogs, but symbiotic nitrogen fixation remains unaffected

No long‐term trends in pCO2 despite increasing organic carbon concentrations in boreal lakes, streams, and rivers

Saltwater reduces CO&lt;sub&gt;2&lt;/sub&gt; and CH&lt;sub&gt;4&lt;/sub&gt; production in organic soils from a coastal freshwater forested wetland

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Product

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No long‐term trends in pCO₂ despite increasing organic carbon concentrations in boreal lakes, streams, and rivers

Saltwater reduces CO<sub>2</sub> and CH<sub>4</sub> production in organic soils from a coastal freshwater forested wetland