气候变化领域集成服务门户(CCPortal): 234Th-Based Carbon Export Flux Along the Indian GEOTRACES GI02 Section in the Arabian Sea and the Indian Ocean

CCPortal

DOI	10.1002/2017GB005847
	234Th-Based Carbon Export Flux Along the Indian GEOTRACES GI02 Section in the Arabian Sea and the Indian Ocean
	Subha Anand S.; Rengarajan R.; Sarma V.V.S.S.
发表日期	2018
ISSN	0886-6236
EISSN	1944-9224
起始页码	417
结束页码	436
卷号	32 期号:3
英文摘要	234Th (t1/2 = 24.1 d), present in seawater, is a naturally occurring particle-reactive radionuclide formed through the radioactive decay of its parent, 238U (t1/2 = 4.47 × 109 years). The 234Th:238U disequilibrium is exploited to quantify fluxes of elements moving out of the euphotic zone by attaching on to sinking particles. Under the Indian GEOTRACES programme, high-resolution sampling in the upper 300 m depth was carried out at 11 stations in the Arabian Sea and the Indian Ocean during April–May 2014 from 17°N to 16°S along 65°E transect to estimate the 234Th-based particulate organic carbon (POC) export flux from the upper ocean. Average 234Th fluxes integrated to 100 m depth were 2,612 and 1,968 dpm m−2 d−1 for the Arabian Sea and the Indian Ocean, respectively. The estimated POC export fluxes ranged from negligible to 9.0 mmol m−2 d−1, and the 234Th-based POC export efficiencies were <2 to 5%. For the same season, the Arabian Sea and the Bay of Bengal showed highly contrasting carbon export trends (mean: 4.0 and 0.8 mmol C m−2 d−1, respectively). The modeled POC export fluxes from in situ and satellite-derived primary production are higher than the 234Th-based values for the Laws and Dunne models and are comparable for the Henson model. The modeled POC fluxes that depend on surface temperature and primary production could be further refined for the seasonal cycle in biological productivity and associated differences in trophic structure, grazing intensity, recycling efficiency, high bacterial activity, and associated dissolved organic carbon (DOC) export. ©2018. American Geophysical Union. All Rights Reserved.
英文关键词	234Th; Arabian Sea; biological carbon pump; GEOTRACES; Indian Ocean; POC export flux
语种	英语
scopus关键词	biogeochemical cycle; biological pump; carbon cycle; euphotic zone; particulate organic carbon; radioactive decay; radionuclide; sampling; seawater; thorium isotope; Arabian Sea; Indian Ocean; Indian Ocean; Bacteria (microorganisms)
来源期刊	Global Biogeochemical Cycles
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/129847
作者单位	Geoscience Division, Physical Research Laboratory, Ahmedabad, India; CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam, India
推荐引用方式 GB/T 7714	Subha Anand S.,Rengarajan R.,Sarma V.V.S.S.. 234Th-Based Carbon Export Flux Along the Indian GEOTRACES GI02 Section in the Arabian Sea and the Indian Ocean[J],2018,32(3).
APA	Subha Anand S.,Rengarajan R.,&Sarma V.V.S.S..(2018).234Th-Based Carbon Export Flux Along the Indian GEOTRACES GI02 Section in the Arabian Sea and the Indian Ocean.Global Biogeochemical Cycles,32(3).
MLA	Subha Anand S.,et al."234Th-Based Carbon Export Flux Along the Indian GEOTRACES GI02 Section in the Arabian Sea and the Indian Ocean".Global Biogeochemical Cycles 32.3(2018).