Particulate organic carbon export fluxes estimates by 234Th238U disequilibrium in the oxygen minimum zone off the Peruvian coast

IF 3 3区地球科学 Q2 CHEMISTRY, MULTIDISCIPLINARY Marine Chemistry Pub Date : 2023-09-30 DOI:10.1016/j.marchem.2023.104325

Wokil Bam , Beat Gasser , Kanchan Maiti , Isabelle Levy , Juan Carlos Miquel , Roberta L. Hansman , Jan Scholten , Ruifang C. Xie , Stefan Sommer , Rainer Kiko , Peter W. Swarzenski

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Abstract

The Peruvian upwelling zone is one of the most productive marine ecosystems in the world with a spectacular, pronounced oxygen minimum zone (OMZ). Globally OMZs are increasing in size and intensity with far-reaching consequences for the marine biological carbon pump and carbon export; thus, these zones need to be carefully monitored to be able to understand future climate change impacts. The current study was carried out in 2013 and 2017 to quantify the vertical flux of organic matter exported out of the productive surface layer by measuring ²³⁴Th²³⁸U disequilibria in the water column. Samples were collected in January 2013 and May 2017 along an identical transect located at 12°S off the Peruvian coast near Lima, Peru. Th-234 fluxes ranged from 0 to 2088 ± 95 dpm m⁻² d⁻¹ in 2013 and 698 ± 63 to 3648 ± 113 dpm m⁻² d⁻¹ in 2017. The corresponding POC fluxes varied between 0 and 164.2 ± 7.9 mg C m⁻² d⁻¹ in 2013 and 22.7 ± 2.7 to 133.1 ± 15.2 mg C m⁻² d⁻¹ in 2017, with POC fluxes gradually decreasing with distance from the coast. Despite higher POC fluxes, the export efficiencies were found to be extremely low due to high particle remineralization rates observed within the euphotic zone.

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秘鲁海岸外氧最小带234Th238U不平衡估算的颗粒有机碳输出通量

秘鲁上升流带是世界上生产力最高的海洋生态系统之一，有一个壮观、明显的氧气最低带（OMZ）。在全球范围内，OMZ的规模和强度正在增加，对海洋生物碳泵和碳出口产生深远影响；因此，需要仔细监测这些区域，以便能够了解未来气候变化的影响。目前的研究于2013年和2017年进行，通过测量水柱中234Th238U的不平衡来量化从生产表层输出的有机物的垂直通量。样本于2013年1月和2017年5月在秘鲁利马附近秘鲁海岸12°S的同一样带上采集。Th-234通量在2013年为0至2088±95 dpm m m−2 d−1，在2017年为698±63至3648±113 dpm m−2中d−1。2013年，相应的POC通量在0至164.2±7.9 mg C m−2 d−1之间变化，2017年为22.7±2.7至133.1±15.2 mg C m m−2 de−1，随着距离海岸的距离，POC通量逐渐减少。尽管POC通量较高，但由于在透光带内观察到较高的颗粒再矿化率，出口效率极低。

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来源期刊

Marine Chemistry 化学-海洋学

CiteScore

6.00

自引率

3.30%

发文量

审稿时长

4.5 months

期刊介绍： Marine Chemistry is an international medium for the publication of original studies and occasional reviews in the field of chemistry in the marine environment, with emphasis on the dynamic approach. The journal endeavours to cover all aspects, from chemical processes to theoretical and experimental work, and, by providing a central channel of communication, to speed the flow of information in this relatively new and rapidly expanding discipline.