Indirect Nitrous Oxide Emission Factors for Agricultural Field Drains and Headwater Streams

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• 作者：Zanist Q. Hama-Aziz ; Kevin M. Hiscock ; Richard J. Cooper
• 刊名：Environmental Science & Technology
• 出版年：2017
• 出版时间：January 3, 2017
• 年：2017
• 卷：51
• 期：1
• 页码：301-307
• 全文大小：405K
• ISSN：1520-5851

文摘

Agriculture is a major source of nitrous oxide (N₂O) emissions, a potent greenhouse gas. While direct N₂O emissions from soils have been widely investigated, indirect N₂O emissions from nitrogen (N) enriched surface water and groundwater bodies are poorly understood. In this contribution, indirect N₂O emissions from subsurface agricultural field drains and headwater streams were monitored over a two-year period (2013–2015) in an intensive arable catchment in eastern England. Indirect N₂O emission factors for groundwater (EF_5g) and surface runoff (EF_5r) were calculated for both field drain and streamwater samples, respectively, using two approaches: the N₂O–N/NO₃–N ratio and the IPCC (2006) methodology. Mean EF_5g values derived from the N₂O–N/NO₃–N ratio were 0.0012 for field drains and 0.0003 for streamwater. Using the IPCC (2006) methodology, the mean EF_5g values were 0.0011 for field drains and 0.0001 for streamwater. Thus, EF values derived from both methods were below the current IPCC (2006) default value of 0.0025 and a downward revision to 0.0012 for EF_5g and 0.0002 for EF_5r is recommended. Such revision would halve current estimates of N₂O emissions associated with nitrogen leaching and runoff from agriculture for both the UK and globally.