反硝化同步底物测定系统（SMODS）的研制

Denitrifcation is a key process to close the global nitrogen cycle. Quantification of denitrification rate and concentrations of soil nitrogen and carbon substrates is the key step for insights into the mechanisms of denitrification process and the patterns of denitrification product (nitrogen gas (N2), nitrous oxide (N2O), nitric oxide (NO) and carbon dioxide (CO2)) fractions. In this project, we prepare to design and build up a new synchronous measurement system for the concentrations of denitrification substrates (SMODS). Development of SMODS includes following three aspects: design and built up, testing of technical parameters and function assessment. As the SMODS developed, the concentrations of denitrification nitrogen and carbon substrates can be detected dynamically. The SMODS works together with the gas-flow-soil-core technique that is used for measuring gas emissions of N2, N2O, NO, CO2 and methane (CH4) due to denitrification. Therefore, the quantitative relationship between denitrification rates and substrate concentrations can be attained with this two measurement systems. SMODS would provide effective technical support for the mechanisms of denitrification process.

反硝化过程是闭合全球氮循环的重要环节。对土壤反硝化速率及碳氮底物动态的同步测定，是研究反硝化过程机理和认识产物（氮气N2、氧化亚氮N2O、一氧化氮NO和二氧化碳CO2）组成变化规律的基础。本项目拟研制一套与反硝化产物动态直接测定系统匹配的底物动态同步测定系统（SMODS）。具体研究内容包括：系统设计与构建，技术参数测试，系统功能评估。SMODS研制成功后，可以用于同步动态监测土壤反硝化过程的碳氮底物浓度，以揭示反硝化速率及其产物组成与碳氮底物的定量关系，为土壤反硝化过程机理研究提供有效的技术支持。

反硝化过程是闭合全球氮循环的重要环节。对土壤反硝化速率及碳氮底物动态的同步测定，是研究反硝化过程机理和认识产物（氮气、氧化亚氮和一氧化氮）组成变化规律的基础。本项目成功研制一套与反硝化气体直接测定系统（GFSC）匹配的底物浓度同步测定系统（SMODS）。该系统由装样系统、气路系统和控制系统三部分组成；可实现培养过程中对底物碳氮浓度的12次测定（每次3重复）。结果显示：通过采用水浴控温，两系统培养温度完全一致；两系统硝态氮（NO3-）浓度测定结果无差异，可溶性有机碳（DOC）浓度测定结果的可存在5-23%的相对偏差；两系统重复测定的NO3-或DOC浓度均无差异（相对偏差<11%）；通过测定含氮气体累积排放可回收土壤NO3-变化量的95-98%。上述结果表明SMODS系统可以很好的配合GFSC系统同步动态监测土壤碳氮底物的浓度变化，该系统的成功研制为土壤反硝化过程机理研究提供有效的技术支持。