Collaborative Research: SitS: Development of multiple-scale sensor and remote sensing technology to quantify abiotic carbon dioxide emission in irrigated soils of aridlands

干旱地区占陆地面积的40%以上，居住着20多亿人口。为了生产更多的粮食和支持不断增长的人口，全世界都在利用密集灌溉将干旱土地变成农田。然而，干旱土地的密集灌溉导致了几个问题，包括蒸发造成的大量水分流失、盐分积累和方解石矿床的形成，这些矿床会堵塞土壤孔隙并改变水分渗透模式。此外，这些方解石矿物的形成伴随着二氧化碳（CO2）的释放，可能会改变区域和全球的碳平衡。该项目的总体目标是推进我们的基本理解的方解石衍生的CO2从干旱的农业土壤中使用的灌溉山核桃果园在埃尔帕索地区沿着格兰德河流域作为试验场的释放。为了实现这一目标，研究人员建议使用一套测量工具，包括便携式CO2同位素分析仪，涡流协方差塔和安装在无人驾驶飞行器上的遥感系统，量化山核桃果园试验场的方解石源CO2排放量。该项目的成功完成将通过收集新的数据和发展关于在干旱土地转变为灌溉农田时有多少非生物二氧化碳释放到大气中的新的基础知识而造福社会。通过学生教育和培训，以及公共宣传，包括指导四名研究生（2名博士和2名硕士），以及UTEP的3名本科生和TAMU的博士后学者，将进一步造福社会。越来越多的证据表明，在灌溉干旱的农业土地上形成的成壤碳酸盐矿物与非生物CO2释放到大气中相结合。最近的研究表明，这种非生物CO2信号来自埃尔帕索山核桃，苜蓿和棉花田的土壤气体。然而，非生物CO2从灌溉干旱农业土壤的释放需要进一步调查，以评估其对区域/全球碳平衡和土壤理化性质的潜在影响。该项目的目标是通过详细测量位于格兰德河河谷埃尔帕索地区的灌溉山核桃果园试验田排放到大气中的非生物CO2通量来解决这一知识差距。为了推进这一目标，研究人员建议使用CO2同位素分析仪、可调谐二极管激光吸收光谱遥感、高光谱成像和耦合涡度协方差通量测量，以高空间和时间分辨率监测山核桃果园试验场的生态系统-大气CO2交换。通过这一综合测量计划，PI希望他们将能够捕捉到非生物CO2通量的时空变化，并确定关键参数/变量（如灌溉强度，水化学和土壤物理化学性质），控制非生物CO2从山核桃果园试验场的释放。因此，该项目的成功完成有可能产生变革性影响，因为它首次详细评估了干旱灌溉土地在区域、国家甚至全球范围内改变土地-大气CO2交换的潜力。国家科学基金会和美国农业部国家粮食和农业研究所之间的合作伙伴关系该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Arid lands cover more than 40% of the terrestrial land surface and host more than two billion people. To produce more food and support a growing population, intensive irrigation is being utilized worldwide to convert arid lands to agricultural fields. However, intensive irrigation of arid lands causes several problems including high water loss through evaporation, salt accumulation, and the formation of calcite mineral deposits, which can clog soil pores and change water-infiltration patterns. Moreover, formation of these calcite minerals is coupled with the release of carbon dioxide (CO2) that could alter regional and global carbon balances. The overarching goal of this project is to advance our fundamental understanding of the release of calcite-derived CO2 from arid agricultural soils using an irrigated pecan orchard in the El Paso region along the Rio Grande valley as a test site. To achieve this goal, the investigators propose to quantify the emission of calcite-derived CO2 from their pecan orchard test site using a suite of measurement tools including portable CO2 isotope analyzers, eddy covariance towers and remote sensing systems mounted on an unmanned aerial vehicle. The successful completion of this project will benefit society through the collection of new data and the development of new fundamental knowledge on how much abiotic CO2 is released to the atmosphere when arid lands are converted to irrigated agricultural fields. Further benefits to society will be achieved through student education and training, and public outreach including the mentoring four graduate students (2 PhD and 2 MS), and 3 undergraduate students at UTEP and a postdoctoral scholar at TAMU.There is growing evidence that the formation of pedogenic carbonate minerals in irrigated arid agricultural lands is coupled with the release of abiotic CO2 to the atmosphere. Recent studies by the investigators of this proposal have identified such abiotic CO2 signals in soil gases from pecan, alfalfa and cotton fields in El Paso. However, the release of abiotic CO2 from irrigated arid agricultural soils needs further investigation to evaluate its potential impact on regional/global carbon balances and soil physicochemical properties. The goal of this project is to address this knowledge gap through detailed measurements of the flux of abiotic CO2 emitted to the atmosphere by an irrigated pecan orchard test field located in the El Paso region of the Rio Grande valley. To advance this goal, the investigators propose to monitor the ecosystem-atmosphere CO2 exchange in the pecan orchard test field with high spatial and temporal resolution using CO2 isotope analyzers, remote sensing with tunable diode laser absorption spectroscopy, hyperspectral imaging, and coupled eddy covariance flux measurements. Through this integrated measurement program, the PIs hope that they will be able to capture the spatiotemporal variations of the abiotic CO2 fluxes, and identify key parameters/variables (e.g. irrigation intensity, water chemistry and soil physicochemical properties) that control the release of abiotic CO2 from their pecan orchard test site. Thus, the successful completion of this project has potential for transformative impact by providing the first detailed assessment of the potential of irrigated arid lands to modify the land-atmosphere CO2 exchange at regional, national and even global scales.Signals in the Soil (SitS) solicitation, a collaborative partnership between the National Science Foundation and the United States Department of Agriculture National Institute of Food and Agriculture (USDA NIFA).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.