Key Lab of Marine Environmental Science and Ecology, Ministry of Education, Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China.
Key Lab of Marine Environmental Science and Ecology, Ministry of Education, Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China.
Water Res. 2019 Nov 15;165:114977. doi: 10.1016/j.watres.2019.114977. Epub 2019 Aug 13.
Intensive agriculture and urbanization have led to the excessive and repeated input of nitrogen (N) into soil and further increased the amount of nitrate (NO) leaching into groundwater, which has become an environmental problem of widespread concern. This review critically examines both the recent advances and remaining knowledge gaps with respect to the N cycle in the vadose zone-groundwater system. The key aspects regarding the N distribution, transformation, and budget in this system are summarized. Three major missing N pieces (N in dissolved organic form, N in the deep vadose zone, and N in the nonagricultural system), which are crucial for closing the N cycle yet has been previously assumed to be insignificant, are put forward and discussed. More work is anticipated to obtain accurate information on the chemical composition, transformation mechanism, and leaching flux of these missing N pieces in the vadose zone-groundwater system. These are essential to support the assessment of global N stocks and management of N contamination risks.
集约化农业和城市化导致氮（N）过度和重复地输入土壤，进一步增加了硝酸盐（NO）向地下水淋滤的数量，这已成为一个广受关注的环境问题。本综述批判性地审查了包气带-地下水系统中氮循环的最新进展和遗留知识空白。总结了该系统中氮分布、转化和预算的关键方面。提出并讨论了三个主要的缺失氮部分（溶解有机形式的氮、深部包气带的氮和非农业系统的氮），这些部分对于闭合氮循环至关重要，但之前被认为不重要。预计需要开展更多工作，以获取包气带-地下水系统中这些缺失氮部分的化学组成、转化机制和淋滤通量的准确信息。这些对于支持全球氮储量评估和氮污染风险管理至关重要。
