Combine sensors, geophysical survey and geochemical tools to investigate pedogenic carbonate precipitation and carbon dioxide emission in irrigated soils of aridlands

边缘干旱地区已被改造成农田，以满足日益增长的粮食生产需求。在这些地区，密集的灌溉，加上高蒸散量和有限的地下水补给，导致了土壤碳酸盐的积累和非生物CO2在农业用地的生产。该项目将是第一个量化这种非生物CO2排放，并确定洪水灌溉，盐负荷和沙漠农业土壤中土壤-大气CO2交换之间的关键联系。这个项目是变革性的，因为它研究了灌溉农业系统中的成土碳酸盐形成，这是一个研究不足但不断被人类活动放大的过程，影响了地球上最大的生物群落之一的碳循环。更重要的是，该项目在全球范围内具有重要的社会经济意义，因为灌溉引起的盐积累和二氧化碳排放量增加需要通过改善农业实践和管理来补救。该项目也是高度相关的推进STEM教育，以美国西南部的代表性人口它将提供跨学科的培训机会，在临界区科学，环境地球物理学和同位素地球化学，以及先进的传感器技术，为研究生和本科生从主要代表性不足的群体在得克萨斯大学埃尔帕索分校（UTEP），其中80%的学生是西班牙裔。该项目将直接资助两名博士。和四名本科生，并提供实地经验和学习机会，环境科学和地质专业，包括为期两周的夏季实地考察。在教育和推广方面，将在每年的“地球科学日”上举办实践活动，该活动通常吸引约2 000名公众参观。研究将考察格兰德河流域沿着的三个农业遗址和一个自然遗址，这些遗址是世界干旱地区的典型和代表。地球化学、地球物理和同位素工具将与新设计的CO2传感器相结合，以测试总体假设，即“灌溉沙漠土壤中的成壤碳酸盐积累向大气排放了重要的温室效应引起的CO2通量。该项目将确定农业土壤中“自然形成”与“灌溉引起”的成壤碳酸盐，分离土壤气体中的“非生物”和“石油呼吸”CO2，并监测非生物CO2从陆地排放到大气的时空变化。通过识别主要控制（包括灌溉强度和化学成分、土壤质地和作物类型），这项实地研究的预期数据集可以外推到大的区域尺度，并对灌溉农业改变土地的潜力提供第一个基本评估-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。

Marginal aridlands have been converted to farmlands to support increasing demand of food production. In these areas, intensive irrigation, coupled with high evapotranspiration and limited groundwater recharge, has led to accumulation of pedogenic carbonate and production of abiotic CO2 in agricultural lands. This project will be among the first to quantify such an abiotic CO2 efflux, and to define key linkages between flood irrigation, salt loading and soil-atmosphere CO2 exchange in desert agricultural soils. This project is transformative in that it examines how pedogenic carbonate formation in irrigated agricultural systems, an under-studied process but continuously magnified by human activities, impacts C cycling in one of the largest biomes on Earth. More importantly, this project has significant socioeconomic relevance at global scales, because irrigation-induced salt accumulation and elevated CO2 efflux need to be remediated through improved agricultural practice and management. This project is also highly relevant for advancing STEM education to representative population of the southwestern U.S. It will provide interdisciplinary training opportunities in Critical Zone Science, environmental geophysics and isotope geochemistry, and advanced sensor technology for both graduate and undergraduate students from primarily under-represented groups at the University of Texas at El Paso (UTEP) where 80% of student body is Hispanic. This project will directly support two Ph.D. and four undergraduate students, and provide field experience and learning opportunities to environmental science and geology majors, including two-week summer field trips. For education and outreach, hands-on activities will be presented at the annual "Earth Science Day" at UTEP, which generally attracts ~2000 visitors from the general public.Three agricultural sites and one natural site along the Rio Grande valley, that are typical and representative of aridland settings worldwide, will be examined in the study. Geochemical, geophysical and isotopic tools will be combined with newly designed CO2 sensors to test the overarching hypothesis that "pedogenic carbonate accumulation in irrigated desert soils emits an important anthropogenically induced flux of CO2 to the atmosphere." The project will identify "naturally formed" versus "irrigation-induced" pedogenic carbonate in agricultural soils, separate "abiotic" and "oil respired" CO2 in soil gases, and monitor the spatiotemporal variation of abiotic CO2 efflux from land to atmosphere at field scales. By identifying the major controls (including irrigation intensity and chemistry, soil texture, and type of crops), expected datasets from this field-based study can be extrapolated to large regional scales and provide the first essential assessment on the potential of irrigated agriculture to modify the land-atmosphere carbon exchange.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.