内蒙古河套灌区盐碱土壤CO2通量变化特征和机制

It is a environmental issue for atmospheric CO2 elevated and global warming in the international community. It is a hot issue that the soil has great potential to mitigate the atmospheric greenhouse effect for the governments and scientists in various countries, and the saline alkali soil may become important places of carbon sequestration of atmospheric CO2. This project is aimed at the characteristics of expanding the area of saline alkali soil, serious alkalization and applying excessive fertilizer on agricultural production in Hetao Irrigation District of Inner Mongolia. Saline alkali soil as the research object in Wulate irrigation area, CO2 flux is observated and comparated for the saline alkali soil of different salinization and different agricultural production in situ observation, the project will be completed: (1) to reveal the dynamic characteristics and driving mechanism of process of soil carbon and seasonal and interannual CO2 fluxes on the saline alkali soil of different salinization and the different agricultural production; (2) to evaluate the saline alkali soil carbon sequestration function on different salinity levels and different agricultural production methods, and to evaluate the potential of CO2 emission reducted on the change of agricultural production; (3) to reveal the soil mechanism to mitigate the atmospheric greenhouse effect on coupling of water and fertilizer, and to clarify the principle of the agricultural production system on sustainable agriculture, carbon sequestration of soil and greenhouse gas emission reducted. The research results will be helpful to reduce the uncertainty of CO2 flux estimation of saline alkali soil and to provide scientific basis and data support in order to mitigate the atmospheric greenhouse effect on the transformation of agricultural production mode.

大气CO2浓度升高和全球变暖是国际社会关注的环境问题。土壤对减缓大气温室效应具有较大潜力是各国政府和科学家关注的热点问题，盐碱土壤可能成为大气CO2重要的固碳场所。本项目针对内蒙古河套灌区“盐碱土壤分布广泛、盐碱程度严重、肥料施用过量”的特点，以乌拉特灌域盐碱土壤为研究对象，通过对盐碱土壤不同盐碱程度和不同农业生产方式碳过程和CO2通量原位观测比较研究，项目将完成：(1)揭示盐碱土壤不同盐碱程度和不同农业生产方式碳过程和CO2通量季节和年际动态特征及驱动机制；(2)评估不同盐碱程度和不同农业生产方式盐碱土壤碳汇功能，评估农业生产方式转变对盐碱土壤CO2减排潜力；(3)揭示水肥耦合减缓大气温室效应的土壤机制，阐明实现土壤固碳、温室气体减排和农业可持续双赢的农业生产体系原理。研究结果将有助于降低我国盐碱土壤CO2通量估算的不确定性，为寻求农业生产方式转变减缓大气温室效应提供科学依据和数据支撑。

本研究以河套灌区盐碱土壤为研究对象，针对不同盐碱程度和不同农业生产方式(不同氮肥施用量、黄河水漫灌和向日葵种植模式)农田盐碱土壤，通过野外原位观测、数值模拟和培养实验，比较河套灌区盐碱土壤不同盐碱程度和不同农业生产方式碳时空变化变化过程、特征和强度，揭示河套灌区盐碱土壤C通量变化发生机制与碳转化参数、土壤因素、盐碱程度、微生物因素、不同水肥耦合、气候因素和生物因素的关系，明确河套灌区盐碱土壤不同盐碱程度不同农业生产方式对C通量的影响规律，高盐土壤(EC 20.00 dS•m−1)CO2通量是负值，吸收CO2，最高值-171 mg•m-2•h-1；揭示河套灌区盐碱土壤C迁移转化机制和最终去向，不同EC盐碱土壤CO2 累积变化量 (ΔCO2)，DIC(可溶性无机碳)变化量(ΔDIC)，CH4累积变化量(ΔCH4)之间显著相关。89% ΔDIC值可以通过ΔCO2值解释(r2=0.8922, n=7)；85% ΔCH4值可以通过ΔDIC值解释(r2=0.8586, n=7)；72% ΔCH4 值可以通过 ΔCO2 值解释(r2=0.7257, n=7)。随土壤EC增加，ΔCO2 值升高，显示土壤具有吸收大气CO2能力。吸收的CO2 被转化为DIC，DIC最终转化为CH4排放。随着ΔCH4增加，CH4累积吸收降低，高EC盐碱土壤降低了碳汇潜力。评估盐碱土壤不同盐碱程度和不同农业生产方式减缓温室效应的潜力，以单位产量温室效应为评价指标，构建利于实现土壤固碳、温室气体减排和农业生产双赢的农业生产体系。发表学术论文7篇，其中，SCI收录2篇，EI收录4篇，CSCD收录1篇；授权国家专利2件；培养硕士生5名，一篇硕士毕业论文获得内蒙古师范大学优秀硕士毕业论文；获得内蒙古师范大学第十四届科研成果科学技术一等奖。