Ebullition of oxygen from seagrasses under supersaturated conditions
Ebullition of oxygen from seagrasses under supersaturated conditions
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DOI：
10.1002/lno.11299
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发表时间：
2019-08-08
影响因子：
4.5
通讯作者：
Zimmerman, Richard C.
中科院分区：
文献类型：
--
作者：
Long, Matthew H.;Sutherland, Kevin;Zimmerman, Richard C.
从水生系统到大气的气体沸腾代表了初级生产中潜在的重要部分，但无法通过溶解气体浓度的测量来量化。虽然经常观察到光合作用表面的气体沸腾，但很少量化。由此产生的低估光合活性可能显着偏差的生态系统营养状态的测定和估计的溶解氧原位测量的地球化学循环速率。在这里，我们量化气体沸腾率在大叶藻滨海草甸在弗吉尼亚州，美国使用简单的漏斗陷阱，并分析了捕获的气体的氧浓度和同位素组成。在高辐照度和低潮同时出现时，观察到氧沸腾的最大小时速率（3.0 mmol氧m（-2）h（-1）），特别是在下午氧和温度最大值出现时。每天的沸腾通量（高达11 mmol氧m（-2）d（-1））大致相当于从溶解氧测量确定的净初级生产率，表明气泡沸腾可以代表初级生产的主要组成部分，通常不包括在生态系统规模的估计。氧含量占捕获的气泡气体体积的20-40%，并与其δ O-18值呈负相关，这与与与海水平衡的大气氧的较高δ O-18和来自光合作用的氧的较低δ O-18之间的混合占优势一致。因此，未来的研究感兴趣的高生产力，浅水生态系统的代谢，特别是那些测量原位氧通量，不应该忽视这里描述的气泡形成和沸腾过程。
Gas ebullition from aquatic systems to the atmosphere represents a potentially important fraction of primary production that goes unquantified by measurements of dissolved gas concentrations. Although gas ebullition from photosynthetic surfaces has often been observed, it is rarely quantified. The resulting underestimation of photosynthetic activity may significantly bias the determination of ecosystem trophic status and estimated rates of biogeochemical cycling from in situ measures of dissolved oxygen. Here, we quantified gas ebullition rates in Zostera marina meadows in Virginia, U.S.A. using simple funnel traps and analyzed the oxygen concentration and isotopic composition of the captured gas. Maximum hourly rates of oxygen ebullition (3.0 mmol oxygen m(-2) h(-1)) were observed during the coincidence of high irradiance and low tides, particularly in the afternoon when oxygen and temperature maxima occurred. The daily ebullition fluxes (up to 11 mmol oxygen m(-2) d(-1)) were roughly equivalent to net primary production rates determined from dissolved oxygen measurements indicating that bubble ebullition can represent a major component of primary production that is not commonly included in ecosystem-scale estimates. Oxygen content comprised 20-40% of the captured bubble gas volume and correlated negatively with its delta O-18 values, consistent with a predominance of mixing between the higher delta O-18 of atmospheric oxygen in equilibrium with seawater and the lower delta O-18 of oxygen derived from photosynthesis. Thus, future studies interested in the metabolism of highly productive, shallow water ecosystems, and particularly those measuring in situ oxygen flux, should not ignore the bubble formation and ebullition processes described here.