We present a method to estimate net community production (NCP) from underway ΔO₂/N₂ observations. This approach, based on high-resolution measurements using relatively low-cost O₂-optode and gas tension device instrumentation, provides an alternative to NCP derivation from mass spectrometric analysis of ΔO₂/Ar. To fully exploit ΔΟ₂/Ν₂ as an NCP tracer, it is necessary to account for differences in surface water argon (Ar) and nitrogen (Ν₂) saturation states. Using a one-dimensional mixed layer model, evaluated against field observations, we examined the divergence between ΔO₂/Ar and ΔΟ₂/Ν₂ resulting from various physical processes. Results show that changes in sea surface temperature, bubble injection and vertical mixing can decouple mixed layer ΔO₂/Ar and ΔΟ₂/Ν₂, while biological N₂-fixation has a negligible effect. Based on readily available environmental data, we developed a framework to correct for Ar and N₂ solubility differences, yielding a new tracer, ΔΟ₂/Ν₂′, that is a near-analog of ΔO₂/Ar. Through model simulations and field measurements, we show that ΔΟ₂/Ν₂′ provides an excellent approximation to ΔO₂/Ar, and that uncertainty and biases in ΔO₂/N₂′ are small relative to other errors in NCP calculations. This work demonstrates the potential for ΔO₂/N₂′ measurements to significantly expand NCP estimates from a variety of sampling platforms.

中文翻译：

---

ΔO2/N2' 作为混合层网络群落生产的示踪剂：理论考虑和概念验证

我们提出了一种根据正在进行的 ΔO ₂ /N ₂观测来估计净群落生产 (NCP) 的方法。这种方法基于使用相对低成本的 O ₂光极和气体张力装置仪器的高分辨率测量，提供了从 ΔO ₂ /Ar 的质谱分析中推导出 NCP 的替代方法。为了充分利用 ΔΟ ₂ /Ν ₂作为 NCP 示踪剂，有必要考虑地表水氩 (Ar) 和氮 (Ν ₂ ) 饱和状态的差异。使用一维混合层模型，根据现场观察进行评估，我们检查了 ΔO ₂ /Ar 和 ΔΟ ₂ /Ν ₂之间的差异由各种物理过程产生。结果表明，海面温度、气泡注入和垂直混合的变化可以使混合层ΔO ₂ /Ar和ΔΟ ₂ /Ν ₂解耦，而生物N _{2 -}固定的影响可以忽略不计。基于现成的环境数据，我们开发了一个框架来校正 Ar 和 N ₂溶解度差异，产生一种新的示踪剂 ΔΟ ₂ /Ν ₂ '，它是 ΔO ₂ /Ar的近似模拟。通过模型模拟和现场测量，我们表明 ΔΟ ₂ /Ν ₂ ′ 提供了对 ΔO ₂的极好近似/Ar，并且ΔO ₂ /N ₂ ' 的不确定性和偏差相对于 NCP 计算中的其他误差很小。这项工作证明了 ΔO ₂ /N ₂ ' 测量值可以显着扩展来自各种采样平台的 NCP 估计值。