Collaborative Research: Bedrock nitrogen and the Earth system: From geobiolgical mechanisms to climate change forecasts

该项目涉及对一系列陆地生态系统和条件下基岩中氮(N)风化速率的控制的基础研究。从分子技术到全球尺度建模。这项研究的动机是需要了解生物地球化学循环如何塑造综合地球系统，并在化石燃料二氧化碳排放不断增加的情况下对气候变化的速度和规模具有关键影响。基岩岩性容纳了地球上99%的活性氮化合物(即除氮气以外的所有氮化合物)；然而，这个巨大的氮气藏的生物地球化学重要性被忽视了。教科书范式认为，新的N完全通过生物化学固定或以N的形式从大气中沉积进入生态系统。然而，这些N输入途径不能解释许多陆地生态系统观察到的高N积累速率，构成了全球N收支中的一个主要未知因素。对陆地碳(C)循环和气候变化产生重大影响。他们建议进行研究，以检验这样一种假设，即沉积成因的岩石代表着陆地生物圈广泛重要的氮源。研究团队包括地质学家、生物学家、土壤学家、生物地球化学家和地球系统科学家。他们将在分子、土壤土壤层、分水岭、区域和全球尺度上研究基岩N的风化。拟议的最先进工具的组合，包括实验室、现场和建模组件，是新颖的。分子尺度的研究集中在地球生物学上；它强调吃岩石的真菌？使用受控实验室实验和现场纳米二次离子质谱仪(NanoSIMS)对N风化反应的影响。土壤沉积物、流域和区域分析将评估氮素在一系列岩性、构造条件和气候中的物理和化学风化。风化速率和陆地氮循环之间的联系将通过测量自然氮稳定同位素以及碳、氮和磷化学的方法在区域范围内进行经验性研究。全球分析将强调一种新的建模方案，该方案将全球生物地球化学模型与风化模型结合起来，以衡量可用于储存全球陆地碳的岩石衍生氮的数量。

This project involves basic research of controls on nitrogen (N) weathering rates from bedrock across an array of terrestrial ecosystems and conditions ? spanning molecular techniques to global scale modeling. This study is motivated by the need to understand how biogeochemical cycles shape integrated Earth systems and has key implications for the pace and magnitude of climate change in the face of rising fossil fuel CO2 emissions. Bedrock lithologies house 99% of all reactive N compounds (i.e., all N forms other than N2 gas) on the planet; yet, the biogeochemical importance of this vast N reservoir has been overlooked. Textbook paradigms hold that new N enters ecosystems solely from the atmosphere via biochemical fixation or as N in deposition. However, these N input pathways are incapable of explaining the high rates of N accumulation observed for many terrestrial ecosystems, constituting a major unknown in the global N budget.As an alternative, the principal investigators suggest that the geosphere plays a major role in terrestrial N biogeochemistry ? imparting large effects on terrestrial carbon (C) cycling and climate change. They propose research to test the hypothesis that rocks of sedimentary origin represent a broadly significant source of N to the terrestrial biosphere. The research team includes geologists, biologists, pedologists, biogeochemists, and Earth system scientists. They will examine bedrock N weathering at molecular-, soil pedon-, watershed-, regional-, and global-scales. The proposed combination of state-of-the-art tools, involving lab, field, and modeling components, is novel. The molecular-scale research is focused on geobiology; it emphasizes ?rock-eating-fungi? effects on N weathering reactions, using controlled laboratory experiments and NanoSIMS (Nanometer-scale Secondary Ion Mass Spectrometry) across field sites. The soil pedon, watershed and regional analyses will estimate physical and chemical weathering of nitrogen across an array of lithologies, tectonic conditions, and climates. Linkages between weathering rates and the terrestrial nitrogen cycle will be empirically investigated regionally through measures of natural nitrogen stable isotopes, and carbon, nitrogen, and phosphorus chemistry. The global analyses will emphasize a new modeling scheme that couples a global biogeochemical model with a weathering model to scale the amount of rock-derived nitrogen that is available to store terrestrial carbon worldwide.