scholarly journals Methane Emissions during the Tide Cycle of a Yangtze Estuary Salt Marsh

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 245
Author(s):  
Yangjie Li ◽  
Dongqi Wang ◽  
Zhenlou Chen ◽  
Jie Chen ◽  
Hong Hu ◽  
...  
Keyword(s):  
Salt Marshes ◽  
Pearson Correlation ◽  
Spring Tide ◽  
Methane Flux ◽  
Yangtze Estuary ◽  
Closed Chamber ◽  
Ch4 Emissions ◽  
Estuarine Wetlands ◽  
Production And Consumption ◽  
Average Flux

Methane (CH4) emissions from estuarine wetlands were proved to be influenced by tide movement and inundation conditions notably in many previous studies. Although there have been several researches focusing on the seasonal or annual CH4 emissions, the short-term CH4 emissions during the tide cycles were rarely studied up to now in this area. In order to investigate the CH4 emission pattern during a tide cycle in Yangtze Estuary salt marshes, frequent fixed-point observations of methane flux were carried out using the in-situ static closed chamber technique. The results indicated that the daily average CH4 fluxes varied from 0.68 mgCH4·m−2·h−1 to 4.22 mgCH4·m−2·h−1 with the average flux reaching 1.78 mgCH4·m−2·h−1 from small tide to spring tide in summer. CH4 fluxes did not show consistent variation with both tide levels and inundation time but increased steadily during almost the whole research period. By Pearson correlation analysis, CH4 fluxes were not correlated with both tide levels (R = −0.014, p = 0.979) and solar radiation (R = 0.024, p = 0.865), but significantly correlated with ambient temperature. It is temperature rather than the tide level mainly controlling CH4 emissions during the tide cycles. Besides, CH4 fluxes also showed no significant correlation with the underground pore-water CH4 concentrations, indicating that plant-mediated transport played a more important role in CH4 fluxes compared with its production and consumption.

Nitrous oxide, dinitrogen and methane emission in a subsurface flow constructed wetland

2003 ◽  
Vol 48 (5) ◽  
pp. 135-142 ◽  
Author(s):  
Ü Mander ◽  
V. Kuusemets ◽  
K. Lõhmus ◽  
T. Mauring ◽  
S. Teiter ◽  
...  
Keyword(s):  
Constructed Wetland ◽  
Subsurface Flow ◽  
Methane Flux ◽  
Soil Core ◽  
Emission Rates ◽  
Closed Chamber ◽  
N Removal ◽  
Average Flux ◽  
Higher Temperature ◽  
Intact Soil Core

N2O, N2 and CH4 fluxes were measured from a horizontal subsurface flow (HSSF) constructed wetland (CW) for wastewater treatment in Estonia. The closed chamber method was used in the field and the He-O method (intact soil core analyses) in the lab throughout the period from October 2001 to June 2002. The average flux of N2O-N, N2-N and CH4-C from various microsites ranged from 0.1 to 59, 4.1 to 1,458 and -0.04 to 2,094 mg m-2 d-1, respectively. A significantly higher flux of N2O was found in chambers installed above the inlet pipes, while the methane flux was higher in the inlet part of the bed with wetter conditions. The groundwater table significantly correlates with gas emission rates of all the gases studied; N2 emission was enhanced by higher temperature of wastewater. PO43- and NH4+ content significantly enhanced, and NO2- and NO3- content inhibited, both N2O and CH4 fluxes. NH4+ showed a negative correlation with N2 flux. Nitrification and denitrification are the main processes of the N removal in the CW covering 42.9%. The specific global warming potential was highest in the wet bed and lowest in the dry bed with lowered water table (32 and 9 g CO2 pe-1 d-1, respectively).

scholarly journals Soil moisture control over autumn season methane flux, Arctic Coastal Plain of Alaska

2012 ◽  
Vol 9 (4) ◽  
pp. 1423-1440 ◽  
Author(s):  
C. S. Sturtevant ◽  
W. C. Oechel ◽  
D. Zona ◽  
Y. Kim ◽  
C. E. Emerson
Keyword(s):  
Large Scale ◽  
Winter Season ◽  
Methane Flux ◽  
Soil Freezing ◽  
The Arctic ◽  
Freezing Process ◽  
Unfrozen Water ◽  
Ch4 Emission ◽  
Ch4 Emissions ◽  
Autumn Season

Abstract. Accurate estimates of annual budgets of methane (CH4) efflux in arctic regions are severely constrained by the paucity of non-summer measurements. Moreover, the incomplete understanding of the ecosystem-level sensitivity of CH4 emissions to changes in tundra moisture makes prediction of future CH4 release from the Arctic extremely difficult. This study addresses some of these research gaps by presenting an analysis of eddy covariance and chamber measurements of CH4 efflux and supporting environmental variables during the autumn season and associated beginning of soil freeze-up at our large-scale water manipulation site near Barrow, Alaska (the Biocomplexity Experiment). We found that the autumn season CH4 emission is significant (accounting for 21–25% of the average growing season emission), and that this emission is mostly controlled by the fraction of inundated landscape, atmospheric turbulence, and the decline in unfrozen water during the period of soil freezing. Drainage decreased autumn CH4 emission by a factor of 2.4 compared to our flooded treatment. Flooding slowed the soil freezing process which has implications for extending elevated CH4 emissions longer into the winter season.

Diurnal changes in oxygen content of the water over the coral reef platform at Heron I

1967 ◽  
Vol 18 (1) ◽  
pp. 23 ◽  
Author(s):  
DW Kinsey ◽  
E Kinsey
Keyword(s):  
Oxygen Content ◽  
High Tide ◽  
Spring Tide ◽  
Algal Species ◽  
Coral Growth ◽  
Diurnal Changes ◽  
Oxygen Levels ◽  
Production And Consumption ◽  
Early Afternoon ◽  
Reef Platform

Heron I., in the Australian Great Barrier Reef, is a small sand cay situated near the western end of a reef 6.5 miles long. The area investigated was south-west of the cay and approximately level, with extensive areas of living coral in the seaward half. Larger algal species were common near the cay but were not in evidence in the areas of active coral growth. Oxygen levels were determined without sampling using a membrane-enclosed polarographic probe. Results are presented as profiles across the platform and also as time sequences in the main draining channel. Some deep water results are included. Oxygen production and consumption were associated primarily with areas of rich coral growth and hence larger algae seemed unimportant in the overall oxygen exchange. Low tide oxygen levels in less than 1 ft of water ranged from 2.1 mg O2/l for a spring tide after midnight to more than 10.8 mg O2/l (the limit of the instrument) in the early afternoon. High tide levels in more than 6 ft of water ranged from 9.0 mg O2/l in the early afternoon to 6.4 mg O2/l 2hr after sunset. High tide readings were not taken late at night. There is some evidence that water already reduced or enriched in oxygen content on the previous tide was returned in significant quantities to the reef platform.

The impact of the change in vegetation structure on the ecological functions of salt marshes: the example of the Yangtze estuary

2013 ◽  
Vol 14 (2) ◽  
pp. 623-632 ◽  
Author(s):  
Xiuzhen Li ◽  
Linjing Ren ◽  
Yu Liu ◽  
Christopher Craft ◽  
Ülo Mander ◽  
...  
Keyword(s):  
Salt Marshes ◽  
Vegetation Structure ◽  
Yangtze Estuary ◽  
Ecological Functions ◽  
The Yangtze Estuary ◽  
The Impact

Improving the reliability of closed chamber methodologies for methane emissions measurement in treatment wetlands

2013 ◽  
Vol 68 (9) ◽  
pp. 2097-2102 ◽  
Author(s):  
Clara Corbella ◽  
Jaume Puigagut
Keyword(s):  
Flux Density ◽  
Mixing Time ◽  
Methane Flux ◽  
Treatment Wetlands ◽  
Flow Strength ◽  
Closed Chamber ◽  
Ca 50 ◽  
The Difference ◽  
Set Up ◽  
Closed Chambers

Non-homogeneous mixing of methane (NHM) within closed chambers was studied under laboratory conditions. The experimental set-up consisted of a PVC vented chamber of 5.3 litres of effective volume fitted with a power-adjustable 12 V fan. NHM within the chamber was studied according to fan position (top vs lateral), fan airflow strength (23 vs 80 cubic feet per minute) and the mixing time before sample withdrawal (5, 10, 15 and 20 minutes). The potential bias of methane flux densities caused by NHM was addressed by monitoring the difference between linearly expected and estimated flux densities of ca. 400, ca. 800 and ca. 1,600 mg CH4.m−2 d−1. Methane within the chamber was under non-homogeneous conditions. Accordingly, methane concentrations at the bottom of the chamber were between 20 to 70% higher than those recorded at the middle or top sections of the chamber, regardless of fan position, fan air-flow strength or time before sample withdrawal. NHM led to notable biases on flux density estimation. Accordingly, flux density estimated from top and middle sampling sections were systematically lower (ca. 50%) than those expected. Flux densities estimated from bottom samples were between 10% higher and 25% lower than expected, regardless of the flux density considered.

scholarly journals Estimating regional-scale methane flux and budgets using CARVE aircraft measurements over Alaska

2018 ◽  
Vol 18 (1) ◽  
pp. 185-202 ◽  
Author(s):  
Sean Hartery ◽  
Róisín Commane ◽  
Jakob Lindaas ◽  
Colm Sweeney ◽  
John Henderson ◽  
...  
Keyword(s):  
Soil Temperature ◽  
Dispersion Model ◽  
Linear Regression Analysis ◽  
Regional Scale ◽  
Methane Flux ◽  
Particle Dispersion ◽  
Environmental Drivers ◽  
Study Region ◽  
Ch4 Emissions ◽  
Soil Temperature And Moisture

Abstract. Methane (CH4) is the second most important greenhouse gas but its emissions from northern regions are still poorly constrained. In this study, we analyze a subset of in situ CH4 aircraft observations made over Alaska during the growing seasons of 2012–2014 as part of the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE). Net surface CH4 fluxes are estimated using a Lagrangian particle dispersion model which quantitatively links surface emissions from Alaska and the western Yukon with observations of enhanced CH4 in the mixed layer. We estimate that between May and September, net CH4 emissions from the region of interest were 2.2 ± 0.5 Tg, 1.9 ± 0.4 Tg, and 2.3 ± 0.6 Tg of CH4 for 2012, 2013, and 2014, respectively. If emissions are only attributed to two biogenic eco-regions within our domain, then tundra regions were the predominant source, accounting for over half of the overall budget despite only representing 18 % of the total surface area. Boreal regions, which cover a large part of the study region, accounted for the remainder of the emissions. Simple multiple linear regression analysis revealed that, overall, CH4 fluxes were largely driven by soil temperature and elevation. In regions specifically dominated by wetlands, soil temperature and moisture at 10 cm depth were important explanatory variables while in regions that were not wetlands, soil temperature and moisture at 40 cm depth were more important, suggesting deeper methanogenesis in drier soils. Although similar environmental drivers have been found in the past to control CH4 emissions at local scales, this study shows that they can be used to generate a statistical model to estimate the regional-scale net CH4 budget.

scholarly journals Summer fluxes of methane and carbon dioxide from a pond and floating mat in a continental Canadian peatland

2016 ◽  
Author(s):  
M. Burger ◽  
S. Berger ◽  
I. Spangenberg ◽  
C. Blodau
Keyword(s):  
Carbon Dioxide ◽  
Hot Spot ◽  
Open Water ◽  
Small Scale ◽  
Co2 Uptake ◽  
Bubble Frequency ◽  
Closed Chamber ◽  
Ch4 Emissions ◽  
Carbon Dioxide Co2 ◽  
Floating Mat

Abstract. Ponds smaller than 10000 m2 likely account for about one third of the global lake perimeter. The release of methane (CH4) and carbon dioxide (CO2) from these ponds is often high and significant on the landscape scale. We measured CO2 and CH4 fluxes in a temperate peatland in southern Ontario, Canada, in summer 2014 along a transect from the open water of a small pond (847 m2) towards the surrounding floating mat (5993 m2) and in a peatland reference area. We used a high-frequency closed chamber technique and distinguished between diffusive and ebullitive CH4 fluxes. CH4 fluxes and CH4 bubble frequency increased from a median of 0.14 (0.00 to 0.43) mmol m−2 h−1 and 4 events m−2 h−1 on the open water to a median of 0.80 (0.20 to 14.97) mmol m−2 h−1 and 168 events m−2 h−1 on the floating mat. The mat was a summer hot spot of CH4 emissions. Fluxes were one order of magnitude higher than at an adjacent peatland site. During daytime the pond was a net source of CO2 equivalents to the atmosphere amounting to 0.13 (−0.02 to 1.06) g CO2 equivalents m−2 h−1, whereas the adjacent peatland site acted as a sink of −0.78 (−1.54 to 0.29) g CO2 equivalents m−2 h−1. The photosynthetic CO2 uptake on the floating mat did not counterbalance the high CH4 emissions, which turned the floating mat into a strong net source of 0.21 (−0.11 to 2.12) g CO2 equivalents m−2h−1. This study highlights the large small-scale variability of CH4 fluxes and CH4 bubble frequency at the peatland-pond interface and the importance of the often large ecotone areas surrounding small ponds as a source of greenhouse gases to the atmosphere.

Redox state affects methane flux in a northern boreal flark fen

2020 ◽  
Author(s):  
Markku Koskinen ◽  
Hanna Finné ◽  
Tarmo Virtanen ◽  
Annalea Lohila ◽  
Raija Laiho ◽  
...  
Keyword(s):  
Redox Potential ◽  
Methane Flux ◽  
Initial Step ◽  
Continuous Variable ◽  
Electron Acceptors ◽  
Soil Redox Potential ◽  
Soil Redox ◽  
Reducing Conditions ◽  
Production And Consumption ◽  
Flux Measurements

<p>Long-term continuous measurement of reduction-oxidation (redox) potential is an emerging tool for analysing ecosystem status. Redox processes are intrinsically linked to methane (CH<sub>4</sub>) production and consumption in soils. Under highly reducing conditions, acetate and carbon dioxide (CO<sub>2</sub>) are reduced into CH<sub>4</sub>, while at less reducing conditions, CH<sub>4</sub> is readily oxidised into CO<sub>2</sub>. These oxidation processes do not necessarily require oxygen; other electron acceptors such as nitrate (NO<sub>3</sub><sup>-</sup>) and iron can also be used by microbes. The prevalence of different electron acceptors and donors is reflected in the redox potential of the soil solution which can be measured. Thus measurements of soil redox potential could in principle be used for predicting CH<sub>4</sub> flux.</p><p>We measured soil redox potential at 4 depths between 5 and 40 cm continuously over one growing season on nine measurement plots on three different microsites (flark, lawn and string), in a north boreal flark fen, while concurrently measuring CO<sub>2</sub> and CH<sub>4</sub> flux of the same plots using the manual chamber method. Flux measurements were conducted five to seven times per week from late June to late September, 2019. Along with the redox potential, water table level (WTL), air and soil temperature (Tair, Tsoil) and several vegetation characteristics were also measured.</p><p>Tsoil was found to be the major control of the momentary CH<sub>4</sub> flux, but after standardizing the flux to 10 C using the Lloyd-Taylor equation, including the soil redox potential was found to significantly (p < 0.001) improve the prediction of the flux over a model incorporating only WTL and momentary Tsoil.</p><p>This is an initial step towards inclusion of redox potential as a continuous variable describing the processes active in the soil into CH<sub>4</sub> production/consumption models.</p>

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