EAPSI:Effect of Humic Substances on Ammonium Oxidation Coupled to Iron Reduction in Paddy Soils

腐殖质对水稻土的铁循环具有重要影响，从而对陆地生态系统氮的流失和滞留产生影响。该项目将确定腐殖质对水稻土中铁还原、铵氧化和随后的氮损失过程的影响。土壤中腐殖质的丰富程度表明，腐殖质对中国水稻土铁循环和氮流失具有重要的潜在影响。生产S合成氮肥。为了确定腐殖质对水稻土中铁和氮循环的影响，将在水稻土中刺激腐殖质、铁和氮循环，并测量氮的损失。此外，还将对受激微生物群落进行分析，以提高对陆地生态系统中负责氮流失和铁循环的微生物的认识。本项目将与中国科学院城市环境研究所朱永冠博士合作完成。朱博士在分析水稻土铁氮循环和微生物群落方面有着丰富的经验。通过在水稻土中刺激铁还原耦合铵氧化，并采用培养非依赖性（16S rRNA基因序列合成测序）和培养依赖性（土壤富集后进行菌落分离）对水稻土微生物群落进行分析。该研究将提高对陆地氮和铁循环机制的认识以及对全球氮损失的估计。该奖项由美国国家科学基金会EAPSI与中国科技部合作资助，支持一名美国研究生的研究。

Humic substances could have a significant impact on iron cycling in paddy soils, resulting in impacts on nitrogen loss and retention in terrestrial ecosystems. This project will determine the effect of humic substances on the process of iron reduction coupled to ammonium oxidation and subsequent nitrogen loss in paddy soils. The abundance of humic substances in soils indicates the significant potential impact of humic substances on iron cycling and on nitrogen loss from paddy soils in China, where one-third of the world?s synthesized nitrogen fertilizer is produced. To determine the impact of humic substances on iron and nitrogen cycling in paddy soils, humic substance, iron, and nitrogen cycling will be stimulated in paddy soils and nitrogen loss will be measured. In addition, the stimulated microbial community will be analyzed to improve the understanding of the microorganisms responsible for nitrogen loss and retention and iron cycling in terrestrial ecosystems. This project will be completed in collaboration with Dr. Yong-Guan Zhu at the Institute for Urban Environment, Chinese Academy of Sciences. Dr. Zhu has extensive experience analyzing paddy soil iron and nitrogen cycling and microbial communities. The stimulated microbial community will be analyzed by stimulating iron reduction coupled to ammonium oxidation in paddy soils and employing culture-independent (sequencing-by-synthesis of 16S rRNA gene sequences) and culture-dependent (soil enrichment followed by colony isolation) microbial community analysis of the paddy soils. The proposed research will improve the mechanistic understanding of terrestrial nitrogen and iron cycling and estimations of global nitrogen loss. This NSF EAPSI award supports the research of a U.S. graduate student and is funded in collaboration with the Chinese Ministry of Science and Technology.