气候变化领域集成服务门户(CCPortal): Dispersion and fate of methane emissions from cold seeps on Hikurangi Margin, New Zealand

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DOI	10.3389/feart.2024.1354388
	Dispersion and fate of methane emissions from cold seeps on Hikurangi Margin, New Zealand
	Law, Cliff S.; Collins, Charine; Marriner, A.; Bury, Sarah J.; Brown, Julie C. S.; Rickard, Graham
发表日期	2024
EISSN	2296-6463
起始页码	12
卷号	12
英文摘要	The influence of cold seep methane on the surrounding benthos is well-documented but the fate of dissolved methane and its impact on water column biogeochemistry remains less understood. To address this, the distribution of dissolved methane was determined around three seeps on the south-east Hikurangi Margin, south-east of New Zealand, by combining data from discrete water column sampling and a towed methane sensor. Integrating this with bottom water current flow data in a dynamic Gerris model determined an annual methane flux of 3 x 105 kg at the main seep. This source was then applied in a Regional Ocean Modelling System (ROMS) simulation to visualize lateral transport of the dissolved methane plume, which dispersed over similar to 100 km in bottom water within 1 year. Extrapolation of this approach to four other regional seeps identified a combined plume volume of 3,500 km3 and annual methane emission of 0.4-3.2 x 106 kg CH4 y-1. This suggests a regional methane flux of 1.1-10.9 x 107 kg CH4 y-1 for the entire Hikurangi Margin, which is lower than previous hydroacoustic estimates. Carbon stable isotope values in dissolved methane indicated that lateral mixing was the primary determinant of methane in bottom water, with potential methane oxidation rates orders of magnitude lower than the dilution rate. Calculations indicate that oxidation of the annual total methane emitted from the five seeps would not significantly alter bottom water dissolved carbon dioxide, oxygen or pH; however, superimposition of methane plumes from different seeps, which was evident in the ROMS simulation, may have localized impacts. These findings highlight the value of characterizing methane release from multiple seeps within a hydrodynamic model framework to determine the biogeochemical impact, climate feedbacks and connectivity of cold seeps on continental shelf margins.
英文关键词	methane; hydrates; hydrodynamic model; methane oxidation; continental shelf; New Zealand; mixing; climate change
语种	英语
WOS研究方向	Geology
WOS类目	Geosciences, Multidisciplinary
WOS记录号	WOS:001204668600001
来源期刊	FRONTIERS IN EARTH SCIENCE
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/304570
作者单位	National Institute of Water & Atmospheric Research (NIWA) - New Zealand; University of Otago; University of London; University College London
推荐引用方式 GB/T 7714	Law, Cliff S.,Collins, Charine,Marriner, A.,et al. Dispersion and fate of methane emissions from cold seeps on Hikurangi Margin, New Zealand[J],2024,12.
APA	Law, Cliff S.,Collins, Charine,Marriner, A.,Bury, Sarah J.,Brown, Julie C. S.,&Rickard, Graham.(2024).Dispersion and fate of methane emissions from cold seeps on Hikurangi Margin, New Zealand.FRONTIERS IN EARTH SCIENCE,12.
MLA	Law, Cliff S.,et al."Dispersion and fate of methane emissions from cold seeps on Hikurangi Margin, New Zealand".FRONTIERS IN EARTH SCIENCE 12(2024).