Surface–atmosphere exchange of ammonia over peatland using QCL-based eddy-covariance measurements and inferential modeling
Surface–atmosphere exchange of ammonia over peatland using QCL-based eddy-covariance measurements and inferential modeling
复制标题
使用基于 QCL 的涡度协方差测量和推理模型进行泥炭地表面-大气氨交换
DOI：
--
复制
发表时间：
2016
期刊：
影响因子：
--
通讯作者：
W. Kutsch
中科院分区：
文献类型：
--
作者：
Undine Zöll;C. Brümmer;F. Schrader;C. Ammann;A. Ibrom;C. Flechard;D. Nelson;M. Zahniser;W. Kutsch
抽象。激光光谱法的最新进展为研究环境相关痕量气体的生态系统-大气交换提供了新的机会。在这项研究中，我们证明了量子级联激光（QCL）吸收光谱仪的适用性，连续测量氨浓度在高时间分辨率，从而量化的净交换之间的一个自然泥炭地生态系统和大气的基础上的涡动协方差方法。氨浓度和通量的日变化模式被发现在不同时期的运动。我们观察到一个明确的转折点，在早春减少氨沉积速度和越来越多的双向通量发生后，开关从休眠植被CO2吸收，但触发了一个显着的天气变化。虽然一些生物物理参数，如温度，辐射和表面湿度被确定为部分调节氨交换的网站，季节性浓度模式显然是由周围地区的农业实践为主。比较补偿点模型与我们的测量为基础的通量估计的结果表明，在某些时期的运动，由于高估了低酸比引起的非气孔阻力相当大的差异。然而，9周后氨的总累积活动交换量仅相差6%，测量和建模分别发现911和857 g NH3-N ha−1沉积。将我们的研究结果外推到一整年，氨沉积低于Hurkuck等人（2014年）在前几年使用扩散管系统的同一地点报告的水平。这可能是由于涡动协方差通量的净信号中的排放分量的更好的表示以及更好地适应模型中的特定站点参数。我们的研究不仅强调了高质量的测量研究和评估陆面-大气相互作用的重要性，而且还表明了QCL光谱仪作为长期监测研究基础设施（如ICOS或氖）中重要的附加仪器在附近氨源较强的站点连续观测活性氮物种的潜力，导致相对较高的平均背景浓度和通量。
Abstract. Recent advances in laser spectrometry offer new opportunities to investigate ecosystem–atmosphere exchange of environmentally relevant trace gases. In this study, we demonstrate the applicability of a quantum cascade laser (QCL) absorption spectrometer to continuously measure ammonia concentrations at high time resolution and thus to quantify the net exchange between a seminatural peatland ecosystem and the atmosphere based on the eddy-covariance approach. Changing diurnal patterns of both ammonia concentration and fluxes were found during different periods of the campaign. We observed a clear tipping point in early spring with decreasing ammonia deposition velocities and increasingly bidirectional fluxes that occurred after the switch from dormant vegetation to CO2 uptake but was triggered by a significant weather change. While several biophysical parameters such as temperature, radiation, and surface wetness were identified to partially regulate ammonia exchange at the site, the seasonal concentration pattern was clearly dominated by agricultural practices in the surrounding area. Comparing the results of a compensation point model with our measurement-based flux estimates showed considerable differences in some periods of the campaign due to overestimation of non-stomatal resistances caused by low acid ratios. The total cumulative campaign exchange of ammonia after 9 weeks, however, differed only in a 6 % deviation with 911 and 857 g NH3-N ha−1 deposition being found by measurements and modeling, respectively. Extrapolating our findings to an entire year, ammonia deposition was lower than reported by Hurkuck et al. (2014) for the same site in previous years using denuder systems. This was likely due to a better representation of the emission component in the net signal of eddy-covariance fluxes as well as better adapted site-specific parameters in the model. Our study not only stresses the importance of high-quality measurements for studying and assessing land surface–atmosphere interactions but also demonstrates the potential of QCL spectrometers for continuous observation of reactive nitrogen species as important additional instruments within long-term monitoring research infrastructures such as ICOS or NEON at sites with strong nearby ammonia sources leading to relatively high mean background concentrations and fluxes.
影响因子：
3.8
作者：
von Bobrutzki, K.;Braban, C. F.;Nemitz, E.
通讯作者：
Nemitz, E.
影响因子：
6.2
作者：
Moffat, Antje M.;Papale, Dario;Stauch, Vanessa J.
通讯作者：
Stauch, Vanessa J.