硅晶表面增强红外衰减全反射光谱原位研究水稻土硝化-反硝化特征及其影响机制

土壤中硝化-反硝化作用是氮素重要转化过程，对农业生产和生态环境建设具有重要意义，但该转化过程涉及土壤中的固相、液相和气相，常规分析方法由于缺乏系统性且需要样品前处理而难以准确定量表征。本研究首先应用红外衰减全反射光谱技术(FTIR-ATR)，针对低含量土壤样本，采用硅晶体，开发新型硅晶衰减全反射附件(Si-ATR)；然后以典型水稻土为材料，优化分析参数，明确硅晶尺寸效应和表面增强效应，融合反卷积方法提取和分离光谱中的目标信息，并应用多元校正算法，实现水稻土中硝态氮及15N标记硝态氮的原位动态监测；同时结合激光诱导击穿原子光谱和红外光声光谱，分别原位监测硝化-反硝化过程中主要电子供体/电子受体(Fe，Mn等)水平以及硝酸还原重要产物N2O排放动态；最后综合分析底物、产物和电子传递特征，明确水稻土硝化-反硝化作用时空分布特征、影响因素及其作用机制，为氮肥高效利用提供理论和技术支撑。

Nitrification-denitrification is one of the import nitrogen transformation processes in soil, which heavily involved in agricultural production and environmental protection. However, this process occurs across solid, liquid and gas phase in soil, which makes it difficult to qualify due to deficiency of systematic methods as well as destruction in soil pretreatment. In this study we makes use of Fourier transformed infrared attenuated total reflectance spectroscopy (FTIR-ATR), and a silicon crystal based ATR accessory (Si-ATR) will be developed; then typical paddy soils will be used to optimize the parameters of the Si-ATR accessory in soil test, analyzing the effects of silicon crystal size and surface, extracting target information in spectrum thorough deconvolution algorithm, reaching the in situ monitoring purpose of nitrate and 15N labelled nitrate using chemometrical methods; at the same time, the levels of electron donor and electron acceptor involved in nitrification-denitrification were qualified by the technique of laser-induced breakdown spectroscopy, while the product from de nitrification of N2O emission was monitored by the technique of Fourier transform infrared photoacoustic spectroscopy; Finally, based on the results of substrate, product and electron transfer, a comprehensive analysis will be made regarding the spatio-temporal distribution of nitrification and denitrification, and the impact factors and the mechanism, which benefit the understanding of nitrogen transformation in soil and support the efficient utilization of nitrogen fertilizer.