Effects of Wind and Buoyancy on Carbon Dioxide Distribution and Air-Water Flux of a Stratified Temperate Lake
Effects of Wind and Buoyancy on Carbon Dioxide Distribution and Air-Water Flux of a Stratified Temperate Lake
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DOI：
10.1029/2017jg004209
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发表时间：
2018-08-01
影响因子：
3.7
通讯作者：
Miller, Scott D.
中科院分区：
文献类型：
--
作者：
Czikowsky, Matthew J.;Maclntyre, Sally;Miller, Scott D.
改进分层湖泊温室气体排放的计算需要了解控制溶解气体在昼夜、天气和季节时间尺度上向空气-水界面输送的物理过程。我们通过结合整个水体的微气象学、物理湖泊学和二氧化碳 (CO2) 测量，在一个温带小型湖泊从夏末到秋季降温的过渡期间解决这个问题。在26天的活动中，湖泊变冷并排放二氧化碳，日均损失23 mmol CO2 m(-2) d(-1)。在昼夜循环中，湖面 pCO(2) 在白天加热期间下降，在夜间冷却期间增加，而由于白天风速较高，白天 CO2 通量超过夜间通量 35%。我们比较了昼夜和天气模式对湖泊内二氧化碳分布和湖泊-大气二氧化碳通量的影响。近地表 pCO(2) 随分层和热损失的增加而增加，从而减缓了溶解气体向混合层的输送。当风速高于 4 m s(-1) 时，湖泊规模的环流会驱动上升流和下降流，从而在东北盆地和西南盆地之间重新分配热量和二氧化碳。在与风暴相关的大风时期，短爆发峰值CO2通量超过50 mmol m(-2) d(-1)。然而，季节性降温引起的持续深层混合的过渡导致混合层和地表的CO2浓度最高，以及持续最高的CO2通量（接近100 mmol m(-2) d(-1)）。
Improved calculations of emissions of greenhouse gases from stratified lakes require understanding the physical processes controlling transport of dissolved gases to the air-water interface on diel, synoptic, and seasonal time scales. We address this issue during the transition from late summer to autumn cooling in a small temperate lake by combining micrometeorology, physical limnology, and carbon dioxide (CO2) measurements throughout the water column. Over the 26-day campaign, the lake cooled and emitted CO2 with daily average loss of 23 mmol CO2 m(-2) d(-1). Over diel cycles, lake surface pCO(2) decreased during daytime heating and increased during nighttime cooling, while daytime CO2 fluxes exceeded nighttime fluxes by 35% due to higher daytime wind speeds. We compared the effects of diel and synoptic weather patterns on the CO2 distribution within the lake and lake-atmosphere CO2 flux. Increases in near-surface pCO(2) scaled with stratification and heat loss which moderated transport of dissolved gases into the mixed layer. When winds were above similar to 4 m s(-1), lake-scale circulations drove upwelling and downwelling that redistributed heat and carbon dioxide between the northeast and southwest basins. Short-burst peak CO2 fluxes exceeded 50 mmol m(-2) d(-1) during windy periods associated with storms. However, the seasonal cooling-induced transition to persistent deep mixing led to the highest CO2 concentrations in the mixed layer and at the surface and the highest sustained CO2 fluxes (approaching 100 mmol m(-2) d(-1)).