土地利用介导的河流氮输出机制研究

人类活动使全球陆地生态系统氮素输入增加了3倍多，引起大量的活性氮流失到水体中，对人体健康和生态环境造成威胁。活性氮从输入到最终输出到河流需要经过多个环节，涉及到多种土地利用类型。研究主要土地利用方式对河流氮输出的源汇贡献，进而实施调控，对区域社会经济和环境的可持续发展至关重要。本项目以浙江省八大流域为研究对象，以人类-自然耦合系统(CHANS)模型为基础，通过各级统计资料、野外调查取样、田间实验、原位监测和文献荟萃分析等手段，拟（1）明确不同土地利用类型对河流氮输出的源汇贡献及其影响因素；（2）揭示基于土地利用以及人类活动强度调控的河流氮输出消减原理。通过情景分析与社会经济可行性分析，本项目拟回答土地利用、自然条件、人类活动强度及其交互作用是如何影响河流氮输出的。本项目的研究结果可为人类活动干扰下的区域水污染提供理论支撑，同时为决策者制定更有效的区域可持续发展策略提供支持。

Human activities have more than tripled the global nitrogen input to terrestrial ecosystems, leading to the losses of a large amount reactive nitrogen (Nr) to water bodies, which poses threats to the environment and human health. The transfer processes of Nr from sources to export to water are complex, which involve many land use types. It is essential to systematically study the contributions of different land use on the source/sink of Nr export to rivers, and thus the implementation of integrated regulations for the sustainable development of regional socio-economy and the environment is important. Taking the eight watersheds in Zhejiang as a case study, this proposal uses nitrogen balance model of Coupled Human And Natural Systems (CHANS) as key, through statistics dataset, field surveys and sampling, field experiments, in-situ observations and meta-analysis of the literature and others, to clear: (1) how different land use types affect the sources/sinks of riverine nitrogen export and the influencing factors; (2) the mitigation strategies of riverine nitrogen export under different human activities and land use types. Furthermore, model simulation will be used to conduct scenario analysis and socioeconomic feasibility analysis of different regulations, to answer how human activities, land use and natural factors interact and affect the riverine nitrogen export. Results of this project will develop theories for regional water pollution, meanwhile, provide supports for decision-makers on more effective and sustainable strategies for regional development.