Winter Limnology as a New Frontier

Powers, Stephen M.; Hampton, Stephanie E.

doi:10.1002/lob.10152

Cited by 53 publications

(44 citation statements)

References 56 publications

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“…Following from work by Striegl et al (2001), a surge of recent research has confirmed that biogenic gases often accumulate over winter in seasonally frozen lakes (Ducharme-Riel et al 2015;Denfeld et al 2016) along with oxidized solutes including nitrate, sulfate, and carbonate/bicarbonate from methane oxidation (Gammons et al 2014;Hanson et al 2006;Powers et al 2017). These findings point to active benthic and planktonic communities (Bertilsson et al 2013;Hampton et al 2017) that affect whole-lake chemistry through sustained aerobic and anaerobic biological processes under ice-which may not be surprising given similar observations from permanently frozen lakes (Morgan-Kiss et al 2016;Powers and Hampton 2016).…”

Section: Introductionmentioning

confidence: 82%

Nitrification contributes to winter oxygen depletion in seasonally frozen forested lakes

et al. 2017

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In lakes that experience seasonal ice cover, understanding of nitrogen-oxygen coupling and nitrification has been dominated by observations during open water, ice-free conditions. To address knowledge gaps about nitrogen-oxygen linkages under ice, we examined long-term winter data (30 ? years, 2-3 sample events per winter) in 7 temperate lakes of forested northern Wisconsin, USA. Across lakes and depths, there were strong negative relationships between dissolved oxygen (DO) and the number of days since ice-on, reflecting consistent DO consumption rates under ice. In two bog lakes that routinely experience prolonged winter DO concentrations below 1.0 mg L -1 , nitrate accumulated near the ice surface mainly in late winter, suggesting nitrification may depend on biogenic oxygen from photosynthesis. In contrast, within five oligotrophicmesotrophic lakes, nitrate accumulated more consistently over winter and often throughout the water column, especially at intermediate depths. Exogenous inputs of nitrate to these lakes were minimal compared to rates of nitrate accumulation. To produce the nitrate via in-lake nitrification, substantial oxygen consumption by ammonium oxidizing microbes would be required. Among lakes and depths that had significant DO depletion over winter, the stoichiometric nitrifier oxygen demand ranged from 1 to 25% of the DO depletion rate. These estimates of nitrifier-driven DO decline are likely conservative because we did not account for nitrate consumed by algal uptake or denitrification. Our results provide an example of nitrification at temperatures \ 5 degrees C having a substantial influence on ecosystem-level nitrogen and oxygen availability in seasonally-frozen, northern forested lakes. Consequently, models of under-ice dissolved oxygen dynamics may be advanced through consideration of nitrification, and more broadly, coupled nitrogen and oxygen cycling.

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Section: Introductionmentioning

confidence: 82%

Nitrification contributes to winter oxygen depletion in seasonally frozen forested lakes

et al. 2017

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“…Processes under ice have usually been considered as less important and on a much smaller scale compared to the ice‐free period, but this view is changing. There is a recent increase in the number of scientific publications addressing physical, chemical, and biological processes under ice cover (Powers and Hampton ). Our results show that the upper 0–200 m layer below the ice cover does not represent a “static landscape” with the well‐mixed upper layer and stratified lower layer that are gradually affected by vertical convection in the spring.…”

Section: Discussionmentioning

confidence: 99%

Giant ice rings on lakes and field observations of lens‐like eddies in the Middle Baikal (2016–2017)

Kouraev

Zakharova

Rémy

et al. 2019

Limnology & Oceanography

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Giant ice rings (diameter 5–7 km) detected on lakes Baikal (Russia) and Hovsgol (Mongolia) are a surface manifestation of intrathermocline lens‐like eddies under ice cover. By analyzing satellite imagery, we have detected new ice rings in 2016 and very old ones in 1969 for Lake Baikal. We have also discovered a giant ice ring on a new water body—Lake Teletskoye in the Altai Republic (Russia). Our recent field observations in the Middle Baikal have high temporal and spatial resolution and coverage and include temperature and current measurements over a long (1.5 month) period. In 2016, an eddy was detected in February and then an eddy and ice ring were detected in March at the same location. In 2017, another eddy was detected in February. This eddy was not stationary, as it was detected 6 km from its initial position in March, and thus no ice ring formed. The results of our field observations provide new data on the size and shape of the eddies. Indirect and direct measurements of currents and temporal evolution of the temperature field make it possible to estimate the rotation period (3 d) for the eddy in 2016 and assess the timing of movement, position, and displacement speed of the eddy in 2017. Thermal infrared Landsat imagery before ice formation in November–December 2015 shows that the eddy in 2016 was formed by the wind‐induced outflow from the Barguzin bay.

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“…The uncertainty in overall magnitude of thermokarst GHG fluxes to the atmosphere is the result of a scarcity of observations (Powers & Hampton, 2016), the poorly understood seasonality of thermokarst lakes (Holgerson & Raymond, 2016), and large differences in emission rates observed among the lakes studied to date (Vonk et al, 2015). The majority of thermokarst lakes are located in regions with limited access for ground observations, particularly during the period of winter snow cover (Arp et al, 2016;Jones et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Winter Accumulation of Methane and its Variable Timing of Release from Thermokarst Lakes in Subarctic Peatlands

2019

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Previous studies of thermokarst lakes have drawn attention to the potential for accumulation of CH 4 under the ice and its subsequent release in spring; however, such observations have not been available for thermokarst waters in carbon-rich peatlands. Here we undertook a winter profiling of five black-water lakes located on eroding permafrost peatlands in subarctic Quebec for comparison with summer profiles and used a 2-year data set of automated water temperature, conductivity, and oxygen measurements to evaluate how the annual mixing dynamics may affect the venting of greenhouse gases to the atmosphere. All of the sampled lakes contained large amounts of dissolved CH 4 under their winter ice cover. These sub-ice concentrations were up to 5 orders of magnitude above air equilibrium (i.e., the expected concentration in lake water equilibrated with the atmosphere), resulting in calculated emission rates at ice breakup that would be 1-2 orders of magnitude higher than midsummer averages. The amount of CO 2 dissolved in the water column was reduced in winter, and the estimated ratio of potential diffusive CO 2 to CH 4 emission in spring was half the measured summer ratio, suggesting a seasonal shift in methanogenesis and bacterial activity. All surface lake ice contained bubbles of CH 4 and CO 2 , but this amounted to <5% of the total amount of the dissolved CH 4 and CO 2 in the corresponding lake water column. The continuous logging records suggested that lake morphometry may play a role in controlling the timing and extent of CH 4 and CO 2 release from the water column to the atmosphere.Plain Language Summary Waterbodies that are formed by the thawing and collapse of ice-rich permafrost ("thermokarst lakes") are known to be major sources of greenhouse emissions in northern landscapes, but the seasonal variation in these emissions is not well understood. In this study, we measured the concentrations of methane and carbon dioxide beneath the ice of five thermokarst lakes in late winter and compared these with summer concentrations and profiles. These "black-water lakes" are located in subarctic peatlands and are darkly colored because of their high concentrations of permafrost-derived, colored organic carbon. The results showed a winter accumulation of gases beneath the ice that would result in 10 to 100 times greater emissions from the surface waters at spring ice breakup than during summer open water conditions. However, continuous in situ measurements of water temperature and oxygen showed that lakes with smaller area to depth ratios may partially retain greenhouse gases that accumulated in their bottom waters throughout winter, thereby limiting the loss of methane in spring that would otherwise occur. More complete mixing occurred during fall cooling and circulation, and release of gases accumulated in the bottom waters during winter and summer may occur at that time. The exact volume of lake water that is mixed during the spring and fall periods is likely related to the wind fetch and depth of the basin. These...

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Winter Limnology as a New Frontier

Cited by 53 publications

References 56 publications

Nitrification contributes to winter oxygen depletion in seasonally frozen forested lakes

Nitrification contributes to winter oxygen depletion in seasonally frozen forested lakes

Giant ice rings on lakes and field observations of lens‐like eddies in the Middle Baikal (2016–2017)

Winter Accumulation of Methane and its Variable Timing of Release from Thermokarst Lakes in Subarctic Peatlands

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