Air‐water CO2 fluxes in the microtidal Neuse River Estuary, North Carolina
Air‐water CO2 fluxes in the microtidal Neuse River Estuary, North Carolina
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DOI：
10.1029/2012jc007925
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发表时间：
2012-08
影响因子：
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通讯作者：
J. Crosswell;M. Wetz;B. Hales;H. Paerl
中科院分区：
文献类型：
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作者：
J. Crosswell;M. Wetz;B. Hales;H. Paerl
[1]从2009年6月到2010年7月，我们沿着北卡罗来纳州纽兹河河口(NRE)的纵向轴线进行了27次地表水二氧化碳分压(PCO2)的连续流动调查，范围从潮汐淡水区到帕姆利科海峡的多盐边界。还在三个水文不同区段的每个区段的边界进行了横向横断面。二氧化碳浓度具有明显的时空变异性。同样，大气-水二氧化碳净通量具有很高的时空变异性，在秋季高河流量条件下，最大[释放]为271mmolCm−2d−1，在晚春风驱动、高初级生产力条件下，−最小[吸收]为38mmolCm−2d−1。在高流量条件下，二氧化碳浓度通常从河口到帕米利科海湾下降，类似于混合良好的系统中看到的模式。在温暖、低流量的条件下，地表水二氧化碳的分布在空间上是可变的，与大多数大潮汐、混合良好的河口的模式不同。从研究区流出的大气-水二氧化碳年流出量为4.7molCm−2yr−1，比以前估计的温带河口少一个数量级。在NRE观测到的二氧化碳通量突出了大潮和小潮系统之间的差异，并表明目前的分类方法可能高估了全球河口的二氧化碳排放量。用大潮和小潮系统的相对表面积来衡量这一较低的外流将使全球河口通量减少42%。
[1] From June 2009 to July 2010, we conducted 27 continuous-flow surveys of surface water CO2 partial pressure (pCO2) along the longitudinal axis of the Neuse River Estuary (NRE), North Carolina ranging from the tidal freshwater region to the polyhaline border with the Pamlico Sound. Lateral transects were also conducted at the borders of each of three hydrologically distinct sections. The pCO2 displayed considerable spatial-temporal variability. Likewise, net air-water CO2 fluxes showed high spatial and temporal variability, with a maximum [release] of 271 mmol C m−2 d−1 during high river flow conditions in fall and minimum [uptake] of −38 mmol C m−2 d−1 during wind-driven, high primary productivity conditions in late spring. During high-flow conditions, pCO2 generally decreased from the river mouth to the Pamlico Sound, similar to patterns seen in well-mixed systems. During warm, low-flow conditions, surface water pCO2 distributions were spatially variable and dissimilar to those patterns seen in most macrotidal, well-mixed estuaries. The annual air-water CO2 efflux from the study area was 4.7 mol C m−2 yr−1, an order of magnitude less than previously estimated for temperate estuaries. The CO2 fluxes observed in the NRE highlight the contrasts between macrotidal and microtidal systems and suggest that global estuarine CO2 emissions are likely overestimated by the current classification approaches. Scaling this lower efflux by the relative surface area of macrotidal and microtidal systems would reduce the global estuarine flux by 42%.