Dynamic coupling of soil structure and gas fluxes measured with distributed sensor systems: implications for carbon modeling

拟议研究的目标是开发两个现场传感器系统，测量不同尺度上的地下气体浓度和应变/水分/温度/吸力，以便提供关于气体通量和土壤结构动态的数据。一种是基于分布式光纤传感器(DFOS)系统，可以提供千米级的测量；另一种是基于低功率传感器和地面网状网无线传感器网络(WSN)系统，以分布式方式提供选定局部点的数据。这两项技术目前都在加州大学伯克利分校(UCB)进行原型制作。开发的传感器系统将首先在科罗拉多矿业学院(CSM)提供的独特的风洞土壤实验设施中进行试验。我们提出了一个控制土壤水分波动的实验计划，旨在通过平衡降水事件的地下水输入和大气扰动(温度、风速和相对湿度)控制的蒸发和蒸散损失来控制土壤水分波动，以便在不断变化的气候条件下做出更有意义的生物地球化学预测和土壤结构变化。在受控环境下，对所研制的传感器系统的精度误差进行量化。开发的系统还将在Rothamsted Research(RR)的领域中实施，以检查其在实际现场条件下的可行性。最终目标是提高对土壤结构变化如何影响大气碳负荷的预测性理解。拟议的传感器开发和实验研究将导致土壤碳模型的实质性改进，例如在RR开发的RothC模型]。模型中的每个隔室由一个具有自己的特征率的一阶过程分解。IOM隔室耐腐烂。该模型通过改变分解过程中释放的二氧化碳和形成的(bio+hum)之间的分配来调整土壤质地及其变化，而不是使用速率修正因子，如用于温度的速率修正因子。此外，CO2排放总量主要受根系呼吸和土壤有机质(包括根际有机碳)的微生物呼吸控制，所有这些过程都对土壤结构高度敏感。因此，在这项拟议的研究中，我们假设土壤结构的变化与土壤气体的产生密切相关。我们将开发和实施测量两者的传感器系统，这反过来将使我们能够量化这种联系。这些新模型将使未来能够预测土壤管理对碳动态的影响，从而了解不同土壤管理策略(例如耕作)对土壤可持续性的影响。这项研究将补充BBSRC在国家能力计划和ISP资金流中支持的RR正在进行的实地研究；特别是关于向植物输送养分的研究。该项目将研究的过程有望改进配方，以包括RR正在开发的多尺度、多物理，方法是：(1)更合理地表示地表-地下耦合过程，(2)包括植被水动力学以及碳和养分分配，以及(3)纳入具有明确和动态微生物表示的土壤和基因组激活的地下反应传输模型。该项目将导致实地开发空间分布的传感系统，该系统可以(1)感知土壤结构的变化，(2)将这些变化与N2O、CH4、CO2和O2进入和离开土壤的通量联系起来。

The goal of the proposed research is to develop two in-situ sensor systems that measure in-ground gas concentrations and strain/moisture/temperature/suction at different scales in order to provide data on the dynamics of gas flux and soil structure. One is based on distributed fiber optic sensor (DFOS) system that can provide measurements at meters to kilometers-scale, whereas the other is based on low-power sensor coupled with in-ground mesh-network wireless sensor network (WSN) system that provides data at selected local points in distributed manner. Both technologies are currently being prototyped at UC Berkeley (UCB). The developed sensor systems will be trialed first in the unique wind tunnel-soil experimental facility available at the Colorado School of Mines (CSM). We propose an experimental plan designed to manipulate soil moisture fluctuations by balancing subsurface water introduction through precipitation events and losses to evaporation and evapotranspiration as controlled by atmospheric perturbations (temperature, wind speed, and relative humidity) so as to make more informed biogeochemical predictions and soil structure changes under changing climate conditions. Under the controlled environment, we will quantify the precision errors of the developed sensor systems. The developed systems will also be implemented in the fields of Rothamsted Research (RR) to examine its feasibility in the actual field conditions. The ultimate goal is to improve the predictive understanding of how atmospheric carbon loading is affected by soil structure changes. The proposed sensor development and experimental research will lead to a substantial improvement of soil carbon models such as the RothC model developed at RR]. Each compartment in the model decomposes by a first-order process with its own characteristic rate. The IOM compartment is resistant to decomposition. The model adjusts for soil texture and its changes by altering the partitioning between CO2 evolved and (BIO+HUM) formed during decomposition, rather than by using a rate modifying factor, such as that used for temperature. Moreover, total CO2 effluxes are largely controlled by root respiration, and microbial respiration of soil organic matter including rhizospheric organic carbon and all of these processes are highly sensitive to soil structure. In this proposed research, we therefore hypothesize that soil structure change is strongly linked to soil gas generation. We will develop and implement sensor systems that measure both, which in turn will allow us to quantify the link. These new models will in the future allow the effects of soil management on carbon dynamics to be predicted and hence give an understanding of the impact of different soil management strategies (e.g. tillage) on soil sustainability. The research will complement ongoing field research at RR supported by the BBSRC in the National Capability scheme and in ISP funding streams; especially on the delivery of nutrients to plants. The processes to be studied in the project are expected to lead to improved formulations to include multi-scale, multi-physics under development at RR by: (1) more rationally representing the coupled surface-subsurface processes, (2) including vegetation hydrodynamics and carbon and nutrient allocation, and (3) incorporating soil and genome-enabled subsurface reactive transport models that have explicit and dynamic microbial representation. The project will lead to the development of spatially-distributed sensing systems in the field that can (1) sense changes in soil stricture and (2) link these changes to fluxes of N2O, CH4, CO2 and O2 into and from soils.