中国江河氧化亚氮的排放及其影响因素

A review of nitrous oxide efflux and associated controls in China′s streams and rivers

氧化亚氮(N2O)是一种在大气中存留时间很长的强效温室气体,并被认为是21世纪破坏臭氧层的重要物质之一,气候预测需要对自然与人为排放的包括N2O在内的温室气体进行全面准确地估算.内陆水体是N2O的重要排放源,由于人为氮输入的增加,江河N2O的排放量可能逐年升高.本研究总结了江河N2O排放速率的研究方法,重点汇总了中国各气候带十大流域江河N2O的溶存浓度和水气界面交换通量,并与世界其他河流进行比较.结果表明我国江河溶存N2O浓度为0.3~1591 nmol·L^-1,N2O释放通量为-12.2~2262.1μmol·m^-2·d^-1,总体与世界其他江河的范围值具有可比性.在此基础上,进一步分析了江河N2O的产生和释放机理,探讨了水中溶解性无机氮、溶解氧、有机碳以及水文、地形地貌与气象条件等对江河N2O产生和释放的影响,并讨论了变化环境下江河N2O的排放特征.

Nitrous oxide(N2O) is a potent greenhouse gas with a long residence time, and it is deemed as one of the foremost destroyers of stratospheric ozone in the 21st century. Climate predictions necessitate a full and robust account of natural and anthropogenic greenhouse gas emissions including N2O. Inland waters are important sources for N2O emissions, and N2O emissions from streams and rivers may increase gradually year by year due to the increased anthropogenic input of reactive nitrogen. In this review, we summarized available data of dissolved concentrations and fluxes of N2O from ten watersheds in diverse climate zones in China. The results showed that the dissolved N2O concentrations ranged from 0.3 to 1591 nmol·L^-1 and the fluxes ranged from-12.2 to 2262.1 μmol·m^-2·d^-1, which were generally comparable to those of other lotic settings around the world. We also analyzed the mechanisms regarding the fluvial production and emission of N2O, and discussed the controlling factors including dissolved inorganic nitrogen, dissolved oxygen, organic carbon as well as hydrological, topographic and meteorological conditions. Furthermore, N2O emissions from streams and rivers under a changing environment have been discussed.