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EAGER SitS: Studying soil biotic and abiotic processes through continuous, high-precision monitoring of soil CO2 an O2 concentrations

EAGER SitS：通过连续、高精度监测土壤二氧化碳和氧气浓度来研究土壤生物和非生物过程

基本信息

批准号：
1841641
负责人：
Daniel Breecker
金额：
$ 29.63万
依托单位：
University of Texas at Austin
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-15 至 2022-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1841641&HistoricalAwards=false
关键词：
EAGER SitS Studying soil biotic

项目摘要

Soils are a vital natural resource, the successful management of which depends on the ability to monitor and understand numerous belowground biotic and abiotic processes. These processes, such as mineral weathering and carbon and nitrogen cycling, directly affect soil health. In order to advance our understanding of these soil processes, this research project will combine continuous, high precision monitoring of soil pore space oxygen, carbon dioxide, and ammonia gas concentrations, each of which are affected by these processes, with the development of a computer model. Undergraduate students who identify with underrepresented groups will be recruited to participate in this research project. The research results will help to quantify soils as a carbon source/sink and inform sustainable land management practices aimed at feeding the expanding global population while managing environmental contamination from fertilizers. These results will be disseminated through courses that the PI teaches, in addition to peer-reviewed publications.The respiratory quotient (RQ, moles of CO2 produced per mole of O2 consumed during respiration) is a fundamental indicator of metabolism that we currently cannot monitor in-situ in soils. Learning about soil community RQ and the factors that affect its variability will help to understand microbial metabolisms, controls on autotrophic and heterotrophic respiration rates, and ultimately soil carbon cycling. Therefore, the goal of this research project is to isolate continuously and monitor in-situ the RQ of the soil community. The first step of this research project will be to expand existing soil physics and chemistry models to quantify the effects of diffusion and gas-water exchange on soil gas composition. The effectiveness of these adapted models will be tested using controlled laboratory experiments. The next step will be to calibrate pore space NH3 and O2 concentrations as a measure of nitrification, using laboratory incubations of soils selected for later field-monitoring. This information is required for accurate determination of RQ, because nitrification consumes O2 in addition to that consumed by respiration. The final step will be to measure continuously and in-situ CO2, O2, and NH3 concentrations in natural soils using commercially-available flow-through sensors coupled to a custom-built autosampler. Simultaneous measurement of soil moisture, soil temperature, and relevant meteorological variables will accompany the soil gas monitoring. The expanded soil physics model and the laboratory soil core calibrations will be used to account for diffusion, water-gas exchange and nitrification in order to determine soil community RQ. Variation in soil community RQ through time and space in grassland and forest soils will be investigated. An improved understanding of natural variability in soil RQ will advance 1) understanding of soil biotic processes, such as how metabolisms in soil change temporally and spatially, and 2) the interaction between biotic and abiotic processes, such as those that drive chemical weathering and calcium carbonate dissolution/precipitation.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.

土壤是一种重要的自然资源，对它的成功管理取决于监测和了解众多地下生物和非生物过程的能力。这些过程，如矿物风化和碳氮循环，直接影响土壤健康。为了促进我们对这些土壤过程的理解，本研究项目将把对土壤孔隙中氧、二氧化碳和氨气浓度的连续、高精度监测与计算机模型的开发结合起来，每种浓度都受到这些过程的影响。认同代表性不足群体的本科生将被招募参与这一研究项目。研究结果将有助于量化土壤作为碳源/碳汇的作用，并为旨在养活不断增长的全球人口的可持续土地管理做法提供信息，同时管理化肥造成的环境污染。这些结果将通过PI教授的课程和同行评议的出版物进行传播。呼吸商(RQ，呼吸过程中每摩尔O2消耗产生的二氧化碳摩尔)是新陈代谢的基本指标，目前我们无法在土壤中进行现场监测。了解土壤群落RQ及其变异性的影响因素将有助于理解微生物代谢，控制自养和异养呼吸速率，并最终实现土壤碳循环。因此，本研究项目的目标是对土壤群落的RQ进行持续的隔离和现场监测。该研究项目的第一步将是扩展现有的土壤物理和化学模型，以量化扩散和气水交换对土壤气体成分的影响。这些经过调整的模型的有效性将通过受控的实验室实验进行测试。下一步将是利用实验室培养的土壤来校准孔隙空间NH3和O2的浓度，作为硝化作用的一种衡量标准，这些土壤被选为稍后进行实地监测的土壤。这一信息是准确测定RQ所必需的，因为除呼吸消耗外，硝化作用还消耗O2。最后一步是使用商业上可用的流通式传感器与定制的自动取样器相耦合，连续和现场测量自然土壤中的二氧化碳、O2和NH3浓度。土壤水分、土壤温度和相关气象变量的同步测量将伴随着土壤气体监测。将使用扩展土壤物理模型和实验室土芯校准来考虑扩散、水-气交换和硝化作用，以确定土壤群落RQ。将调查草地和森林土壤中土壤群落RQ随时间和空间的变化。更好地理解土壤RQ中的自然变异性将促进1)对土壤生物过程的理解，例如土壤中的新陈代谢如何在时间和空间上变化，以及2)生物和非生物过程之间的相互作用，例如那些驱动化学风化和碳酸钙溶解/沉淀的过程。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。