scholarly journals Canopy uptake dominates nighttime carbonyl sulfide fluxes in a boreal forest

2017 ◽  
Author(s):  
Linda M. J. Kooijmans ◽  
Kadmiel Maseyk ◽  
Ulli Seibt ◽  
Wu Sun ◽  
Timo Vesala ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Stomatal Closure ◽  
Carbonyl Sulfide ◽  
Tracer Method ◽  
Dry Period ◽  
Canopy Layer ◽  
Night Time ◽  
Canopy Uptake ◽  
Incomplete Closure ◽  
Chamber Measurements

Abstract. Nighttime vegetative uptake of carbonyl sulfide (COS) can exist due to the incomplete closure of stomata and the light-independence of the enzyme carbonic anhydrase, which complicates the use of COS as a tracer for gross primary productivity (GPP). In this study we derived nighttime COS fluxes in a boreal forest (the SMEAR II station in Hyytiälä, Finland; 61°51′ N, 24°17′ E, 181 m ASL) from June to November 2015 using two different methods: eddy-covariance (EC) measurements (FCOS-EC) and the radon-tracer method (FCOS-Rn). The nighttime COS fluxes averaged over the whole measurement period were −8.1 ± 1.5 and −7.9 ± 3.8 pmol m−2 s−1 for FCOS-Rn and FCOS-EC, respectively, which is 38 % of the average daytime fluxes and 21 % of the total daily COS uptake. The correlation of 222Radon (of which the source is the soil) with COS (average R2 = 0.59) was lower than with CO2 (0.79), suggesting that the main sink of COS is not located at the ground. These observations are supported by soil chamber measurements that show that soil contributes to only 33 % of the total nighttime COS uptake. We found a decrease of COS uptake with decreasing night-time stomatal conductance and increasing VPD and air temperature, driven by stomatal closure in response to a warm and dry period in August. We also discuss the effect that canopy layer mixing can have on the radon-tracer method and the sensitivity of FCOS-EC to atmospheric turbulence. Our results suggest that the nighttime uptake of COS is mainly driven by the tree foliage and is significant in a boreal forest, such that it needs to be taken into account when using COS as a tracer for GPP.

scholarly journals Canopy uptake dominates nighttime carbonyl sulfide fluxes in a boreal forest

2017 ◽  
Vol 17 (18) ◽  
pp. 11453-11465 ◽  
Author(s):  
Linda M. J. Kooijmans ◽  
Kadmiel Maseyk ◽  
Ulli Seibt ◽  
Wu Sun ◽  
Timo Vesala ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Stomatal Closure ◽  
Carbonyl Sulfide ◽  
Tracer Method ◽  
Dry Period ◽  
Canopy Layer ◽  
Canopy Uptake ◽  
Incomplete Closure ◽  
Chamber Measurements ◽  
Measurement Period

Abstract. Nighttime vegetative uptake of carbonyl sulfide (COS) can exist due to the incomplete closure of stomata and the light independence of the enzyme carbonic anhydrase, which complicates the use of COS as a tracer for gross primary productivity (GPP). In this study we derived nighttime COS fluxes in a boreal forest (the SMEAR II station in Hyytiälä, Finland; 61°51′ N, 24°17′ E; 181 m a.s.l.) from June to November 2015 using two different methods: eddy-covariance (EC) measurements (FCOS-EC) and the radon-tracer method (FCOS-Rn). The total nighttime COS fluxes averaged over the whole measurement period were −6.8 ± 2.2 and −7.9 ± 3.8 pmol m−2 s−1 for FCOS-Rn and FCOS-EC, respectively, which is 33–38 % of the average daytime fluxes and 21 % of the total daily COS uptake. The correlation of 222Rn (of which the source is the soil) with COS (average R2  =  0.58) was lower than with CO2 (0.70), suggesting that the main sink of COS is not located at the ground. These observations are supported by soil chamber measurements that show that soil contributes to only 34–40 % of the total nighttime COS uptake. We found a decrease in COS uptake with decreasing nighttime stomatal conductance and increasing vapor-pressure deficit and air temperature, driven by stomatal closure in response to a warm and dry period in August. We also discuss the effect that canopy layer mixing can have on the radon-tracer method and the sensitivity of (FCOS-EC) to atmospheric turbulence. Our results suggest that the nighttime uptake of COS is mainly driven by the tree foliage and is significant in a boreal forest, such that it needs to be taken into account when using COS as a tracer for GPP.

scholarly journals Supplementary material to "Canopy uptake dominates nighttime carbonyl sulfide fluxes in a boreal forest"

2017 ◽  
Author(s):  
Linda M. J. Kooijmans ◽  
Kadmiel Maseyk ◽  
Ulli Seibt ◽  
Wu Sun ◽  
Timo Vesala ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Carbonyl Sulfide ◽  
Canopy Uptake ◽  
Supplementary Material

Impact of high daytime air humidity on nutrient uptake and night-time water flux in silver birch, a boreal forest tree species

2017 ◽  
Vol 17 (7) ◽  
pp. 2149-2157 ◽  
Author(s):  
Priit Kupper ◽  
Gristin Rohula ◽  
Liina Inno ◽  
Ivika Ostonen ◽  
Arne Sellin ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Nutrient Uptake ◽  
Tree Species ◽  
Water Flux ◽  
Forest Tree ◽  
Silver Birch ◽  
Air Humidity ◽  
Night Time ◽  
Forest Tree Species

scholarly journals Stomatal control of leaf fluxes of carbonyl sulfide and CO<sub>2</sub> in a <i>Typha</i> freshwater marsh

2018 ◽  
Vol 15 (11) ◽  
pp. 3277-3291 ◽  
Author(s):  
Wu Sun ◽  
Kadmiel Maseyk ◽  
Céline Lett ◽  
Ulli Seibt
Keyword(s):  
Stomatal Closure ◽  
Carbonyl Sulfide ◽  
Co2 Assimilation ◽  
Stomatal Resistance ◽  
Freshwater Marsh ◽  
Co2 Uptake ◽  
Stomatal Control ◽  
Environmental Controls ◽  
High Vapor ◽  
Assimilation Capacity

Abstract. Carbonyl sulfide (COS) is an emerging tracer to constrain land photosynthesis at canopy to global scales, because leaf COS and CO2 uptake processes are linked through stomatal diffusion. The COS tracer approach requires knowledge of the concentration normalized ratio of COS uptake to photosynthesis, commonly known as the leaf relative uptake (LRU). LRU is known to increase under low light, but the environmental controls over LRU variability in the field are poorly understood due to scant leaf scale observations. Here we present the first direct observations of LRU responses to environmental variables in the field. We measured leaf COS and CO2 fluxes at a freshwater marsh in summer 2013. Daytime leaf COS and CO2 uptake showed similar peaks in the mid-morning and late afternoon separated by a prolonged midday depression, highlighting the common stomatal control on diffusion. At night, in contrast to CO2, COS uptake continued, indicating partially open stomata. LRU ratios showed a clear relationship with photosynthetically active radiation (PAR), converging to 1.0 at high PAR, while increasing sharply at low PAR. Daytime integrated LRU (calculated from daytime mean COS and CO2 uptake) ranged from 1 to 1.5, with a mean of 1.2 across the campaign, significantly lower than the previously reported laboratory mean value (∼ 1.6). Our results indicate two major determinants of LRU – light and vapor deficit. Light is the primary driver of LRU because CO2 assimilation capacity increases with light, while COS consumption capacity does not. Superimposed upon the light response is a secondary effect that high vapor deficit further reduces LRU, causing LRU minima to occur in the afternoon, not at noon. The partial stomatal closure induced by high vapor deficit suppresses COS uptake more strongly than CO2 uptake because stomatal resistance is a more dominant component in the total resistance of COS. Using stomatal conductance estimates, we show that LRU variability can be explained in terms of different patterns of stomatal vs. internal limitations on COS and CO2 uptake. Our findings illustrate the stomata-driven coupling of COS and CO2 uptake during the most photosynthetically active period in the field and provide an in situ characterization of LRU – a key parameter required for the use of COS as a photosynthetic tracer.

scholarly journals Soil fluxes of carbonyl sulfide (COS), carbon monoxide, and carbon dioxide in a boreal forest in southern Finland

2018 ◽  
Vol 18 (2) ◽  
pp. 1363-1378 ◽  
Author(s):  
Wu Sun ◽  
Linda M. J. Kooijmans ◽  
Kadmiel Maseyk ◽  
Huilin Chen ◽  
Ivan Mammarella ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Soil Respiration ◽  
Boreal Forest ◽  
Boreal Forests ◽  
Carbonyl Sulfide ◽  
Co2 Flux ◽  
Growing Season ◽  
Uptake Rates ◽  
Scots Pine Forest ◽  
Microbial Groups

Abstract. Soil is a major contributor to the biosphere–atmosphere exchange of carbonyl sulfide (COS) and carbon monoxide (CO). COS is a tracer with which to quantify terrestrial photosynthesis based on the coupled leaf uptake of COS and CO2, but such use requires separating soil COS flux, which is unrelated to photosynthesis, from ecosystem COS uptake. For CO, soil is a significant natural sink that influences the tropospheric CO budget. In the boreal forest, magnitudes and variabilities of soil COS and CO fluxes remain poorly understood. We measured hourly soil fluxes of COS, CO, and CO2 over the 2015 late growing season (July to November) in a Scots pine forest in Hyytiälä, Finland. The soil acted as a net sink of COS and CO, with average uptake rates around 3 pmol m−2 s−1 for COS and 1 nmol m−2 s−1 for CO. Soil respiration showed seasonal dynamics controlled by soil temperature, peaking at around 4 µmol m−2 s−1 in late August and September and dropping to 1–2 µmol m−2 s−1 in October. In contrast, seasonal variations of COS and CO fluxes were weak and mainly driven by soil moisture changes through diffusion limitation. COS and CO fluxes did not appear to respond to temperature variation, although they both correlated well with soil respiration in specific temperature bins. However, COS : CO2 and CO : CO2 flux ratios increased with temperature, suggesting possible shifts in active COS- and CO-consuming microbial groups. Our results show that soil COS and CO fluxes do not have strong variations over the late growing season in this boreal forest and can be represented with the fluxes during the photosynthetically most active period. Well-characterized and relatively invariant soil COS fluxes strengthen the case for using COS as a photosynthetic tracer in boreal forests.

Satellite and Ground Estimates of Surface and Canopy-Layer Urban Heat Island

2021 ◽  
Vol 12 (4) ◽  
pp. 1-21
Author(s):  
Bakul Budhiraja ◽  
Prasad Pathak ◽  
Girish Agarwal ◽  
Raja Sengupta
Keyword(s):  
Urban Heat Island ◽  
Temperate Climate ◽  
Seasonal Patterns ◽  
Heat Island ◽  
Canopy Layer ◽  
Night Time ◽  
Holistic View ◽  
Climate Zones ◽  
Tropical Cities ◽  
Urban Heat

The urban heat island (UHI) effect is one of the prominent impacts of urbanization that affects human health and energy consumption. As the data is limited and inconsistent, UHI comparative studies between UHIUCL and UHISurf on the seasonal scale are limited. The use of only daytime summer imagery reporting “Inverted UHI” undermines the holistic view of the phenomenon. Therefore, this study analyses the seasonal patterns for UHISurf and UHIUCL in three climate zones (Delhi, Pune, and Montreal). The three cities experience a high traditional night-time UHIUCL (Delhi 7°C, Pune 6°C, Montreal 1.89°C). Landsat captures a prominent daytime UHISurf (15°C) in Montreal with temperate climate and daytime inverted UHISurf (-4°C) for Delhi in summer. Seasonally, the night-time UHI is prominent in summer and monsoon for Delhi, summer and spring for Pune, and summer for Montreal. Due to UHI effect, the heatwaves can be more intense in semi-arid and tropical cities than temperate cities.

scholarly journals Methane emissions from boreal and tropical forest ecosystems derived from in-situ measurements

2007 ◽  
Vol 7 (5) ◽  
pp. 14011-14039 ◽  
Author(s):  
V. Sinha ◽  
J. Williams ◽  
P. J. Crutzen ◽  
J. Lelieveld
Keyword(s):  
Boreal Forest ◽  
Tropical Forest ◽  
Tropical Forests ◽  
Forest Ecosystem ◽  
Boreal Forests ◽  
Forest Ecosystems ◽  
Global Budget ◽  
Night Time ◽  
Mixing Ratios ◽  
The Impact

Abstract. Methane is a climatologically important greenhouse gas, which plays a key role in regulating water vapour in the stratosphere and hydroxyl radicals in the troposphere. Recent findings that vegetation emits methane have stimulated efforts to ascertain the impact of this source on the global budget. In this work, we present the results of high frequency (ca. 1 min−1) methane measurements conducted in the boreal forests of Finland and the tropical forests of Suriname, in April–May, 2005 and October 2005 respectively. The measurements were performed using a gas chromatograph – flame ionization detector (GC-FID). The average of the median mixing ratios during a typical diel cycle were 1.83 μmol mol−1 and 1.74 μmol mol−1 for the boreal forest ecosystem and tropical forest ecosystem respectively, with remarkable similarity in the time series of both the boreal and tropical diel profiles. Night time methane emission flux of the boreal forest ecosystem, calculated from the increase of methane during the night and measured nocturnal boundary layer heights yields a flux of (3.62±0.87)×1011 molecules cm−2 s−1(or 45.5±11 Tg CH4 yr−1 for global boreal forest area). This is a source contribution of circa 8% of the global methane budget. These results highlight the importance of the boreal and tropical forest ecosystems for the global budget of methane. The results are also discussed in the context of recent work reporting high methane mixing ratios over tropical forests using space borne near infra-red spectroscopy measurements.

scholarly journals Alkyl nitrates in the boreal forest: Formation via the NO<sub>3</sub>, OH and O<sub>3</sub> induced oxidation of BVOCs and ambient lifetimes

2019 ◽  
Author(s):  
Jonathan Liebmann ◽  
Nicolas Sobanski ◽  
Jan Schuladen ◽  
Einar Karu ◽  
Heidi Hellén ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Organic Aerosol ◽  
High Reactivity ◽  
Anthropogenic Sources ◽  
Reactive Nitrogen ◽  
Biogenic Emissions ◽  
Organic Nitrates ◽  
Night Time ◽  
Alkyl Nitrates ◽  
Volatile Organic

Abstract. The formation of alkyl nitrates in various oxidation processes taking place throughout the diel cycle can represent an important sink of reactive nitrogen and mechanism for chain-termination in atmospheric photo-oxidation cycles. The low volatility alkyl nitrates formed from biogenic volatile organic compounds (BVOCs), especially terpenoids, enhance rates of production and growth of secondary organic aerosol. Measurements of the NO3-reactivity and the mixing ratio of total alkyl nitrates in the Finnish boreal forest enabled assessment of the relative importance of NO3−, O3− and OH-initiated formation of alkyl-nitrates from BVOCs in this environment. The high reactivity of the forest air towards NO3 resulted in reactions of the nitrate radical with terpenes contributing substantially to formation of ANs not only during the night but also during daytime. Overall, night-time reactions of NO3 accounted for 49 % of the local production rate of ANs, with contributions of 21 %, 18 % and 12 % for NO3, OH and O3, during the day. The lifetimes of the gas-phase ANs formed in this environment were of the order of 2 hours implying that the lifetime of NOx is strongly controlled by biogenic emissions from the forest. As the organic nitrates are lost to the particle phase and via dry-deposition to foliar surfaces, the overall result is transfer of reactive nitrogen from anthropogenic sources to the forest ecosystem.

scholarly journals Alkyl nitrates in the boreal forest: formation via the NO<sub>3</sub>-, OH- and O<sub>3</sub>-induced oxidation of biogenic volatile organic compounds and ambient lifetimes

2019 ◽  
Vol 19 (15) ◽  
pp. 10391-10403 ◽  
Author(s):  
Jonathan Liebmann ◽  
Nicolas Sobanski ◽  
Jan Schuladen ◽  
Einar Karu ◽  
Heidi Hellén ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Boreal Forest ◽  
Organic Compounds ◽  
High Reactivity ◽  
Anthropogenic Sources ◽  
Reactive Nitrogen ◽  
Biogenic Volatile Organic Compounds ◽  
Night Time ◽  
Alkyl Nitrates ◽  
Volatile Organic

Abstract. The formation of alkyl nitrates in various oxidation processes taking place throughout the diel cycle can represent an important sink of reactive nitrogen and mechanism for chain termination in atmospheric photo-oxidation cycles. The low-volatility alkyl nitrates (ANs) formed from biogenic volatile organic compounds (BVOCs), especially terpenoids, enhance rates of production and growth of secondary organic aerosol. Measurements of the NO3 reactivity and the mixing ratio of total alkyl nitrates (ΣANs) in the Finnish boreal forest enabled assessment of the relative importance of NO3-, O3- and OH-initiated formation of alkyl nitrates from BVOCs in this environment. The high reactivity of the forest air towards NO3 resulted in reactions of the nitrate radical, with terpenes contributing substantially to formation of ANs not only during the night but also during daytime. Overall, night-time reactions of NO3 accounted for 49 % of the local production rate of ANs, with contributions of 21 %, 18 % and 12 % for NO3, OH and O3 during the day. The lifetimes of the gas-phase ANs formed in this environment were on the order of 2 h due to efficient uptake to aerosol (and dry deposition), resulting in the transfer of reactive nitrogen from anthropogenic sources to the forest ecosystem.

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