Methane emission dynamics among CO2-absorbing and thermokarst lakes of a great Arctic delta
Lake-rich Arctic deltas differ biogeochemically from tundra lakes, and their role as sources and sinks of greenhouse gases remains poorly understood. Under-ice and open-water changes in methane (CH4) storage (43 lakes, 2014), floating chamber measurements of total and diffusive CH4 evasion to the at...
Main Authors: | , , |
---|---|
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
2021
|
Subjects: | |
Online Access: | http://summit.sfu.ca/item/21477 |
id |
ftsimonfu:oai:summit.sfu.ca:21477 |
---|---|
record_format |
openpolar |
spelling |
ftsimonfu:oai:summit.sfu.ca:21477 2023-05-15T14:55:34+02:00 Methane emission dynamics among CO2-absorbing and thermokarst lakes of a great Arctic delta Cunada, Christopher L. Lesack, Lance F. W. Tank, Suzanne E. 2021-09-28 http://summit.sfu.ca/item/21477 English eng http://summit.sfu.ca/item/21477 Article 2021 ftsimonfu 2022-04-07T18:44:06Z Lake-rich Arctic deltas differ biogeochemically from tundra lakes, and their role as sources and sinks of greenhouse gases remains poorly understood. Under-ice and open-water changes in methane (CH4) storage (43 lakes, 2014), floating chamber measurements of total and diffusive CH4 evasion to the atmosphere (6 lakes, 2014-2015), and water-column CH4 oxidation (MOX) (6 lakes, 2014-2015) permitted evaluation of how CH4 emissions vary among lakes with differing river-to-lake connection times within the Mackenzie Delta. CH4 emissions during ice-out were considerable, followed by substantial declines as open-water progressed. Water-column MOX rates were highest after ice-out, and declined throughout open-water. After accounting for a strong effect of CH4 substrate levels, MOX rates were inversely related to pH, which can increase to high levels during open-water because of high macrophyte production. Comparisons of water-column CH4 storage versus open-water fluxes (6 lakes) showed that diffusive evasion plus MOX removed most CH4 in the water columns every 1-2 days with only modest changes in storage, suggesting that counter-balancing water-column replenishment is substantial. Lakes with short river-connection times (i.e. most strongly autotrophic and strongly CO2- absorbing in this delta) and thermokarst lakes contribute disproportionately to CH4 flux, relative to lakes with long river-connection times. Thus, this great Arctic delta represents an important system of greenhouse-gas emitting lakes despite prior work showing their net absorption of CO2 during open-water, and having a low landscape area of CO2-saturated thermokarst lakes. Autotrophically absorbed CO2 becomes labile carbon substrate, and is microbially shunted back to the atmosphere as the more potent greenhouse gas CH4. Article in Journal/Newspaper Arctic Mackenzie Delta Thermokarst Tundra Summit - SFU Research Repository (Simon Fraser University) Arctic Mackenzie Delta ENVELOPE(-136.672,-136.672,68.833,68.833) |
institution |
Open Polar |
collection |
Summit - SFU Research Repository (Simon Fraser University) |
op_collection_id |
ftsimonfu |
language |
English |
description |
Lake-rich Arctic deltas differ biogeochemically from tundra lakes, and their role as sources and sinks of greenhouse gases remains poorly understood. Under-ice and open-water changes in methane (CH4) storage (43 lakes, 2014), floating chamber measurements of total and diffusive CH4 evasion to the atmosphere (6 lakes, 2014-2015), and water-column CH4 oxidation (MOX) (6 lakes, 2014-2015) permitted evaluation of how CH4 emissions vary among lakes with differing river-to-lake connection times within the Mackenzie Delta. CH4 emissions during ice-out were considerable, followed by substantial declines as open-water progressed. Water-column MOX rates were highest after ice-out, and declined throughout open-water. After accounting for a strong effect of CH4 substrate levels, MOX rates were inversely related to pH, which can increase to high levels during open-water because of high macrophyte production. Comparisons of water-column CH4 storage versus open-water fluxes (6 lakes) showed that diffusive evasion plus MOX removed most CH4 in the water columns every 1-2 days with only modest changes in storage, suggesting that counter-balancing water-column replenishment is substantial. Lakes with short river-connection times (i.e. most strongly autotrophic and strongly CO2- absorbing in this delta) and thermokarst lakes contribute disproportionately to CH4 flux, relative to lakes with long river-connection times. Thus, this great Arctic delta represents an important system of greenhouse-gas emitting lakes despite prior work showing their net absorption of CO2 during open-water, and having a low landscape area of CO2-saturated thermokarst lakes. Autotrophically absorbed CO2 becomes labile carbon substrate, and is microbially shunted back to the atmosphere as the more potent greenhouse gas CH4. |
format |
Article in Journal/Newspaper |
author |
Cunada, Christopher L. Lesack, Lance F. W. Tank, Suzanne E. |
spellingShingle |
Cunada, Christopher L. Lesack, Lance F. W. Tank, Suzanne E. Methane emission dynamics among CO2-absorbing and thermokarst lakes of a great Arctic delta |
author_facet |
Cunada, Christopher L. Lesack, Lance F. W. Tank, Suzanne E. |
author_sort |
Cunada, Christopher L. |
title |
Methane emission dynamics among CO2-absorbing and thermokarst lakes of a great Arctic delta |
title_short |
Methane emission dynamics among CO2-absorbing and thermokarst lakes of a great Arctic delta |
title_full |
Methane emission dynamics among CO2-absorbing and thermokarst lakes of a great Arctic delta |
title_fullStr |
Methane emission dynamics among CO2-absorbing and thermokarst lakes of a great Arctic delta |
title_full_unstemmed |
Methane emission dynamics among CO2-absorbing and thermokarst lakes of a great Arctic delta |
title_sort |
methane emission dynamics among co2-absorbing and thermokarst lakes of a great arctic delta |
publishDate |
2021 |
url |
http://summit.sfu.ca/item/21477 |
long_lat |
ENVELOPE(-136.672,-136.672,68.833,68.833) |
geographic |
Arctic Mackenzie Delta |
geographic_facet |
Arctic Mackenzie Delta |
genre |
Arctic Mackenzie Delta Thermokarst Tundra |
genre_facet |
Arctic Mackenzie Delta Thermokarst Tundra |
op_relation |
http://summit.sfu.ca/item/21477 |
_version_ |
1766327604009238528 |