The Carbon:234Thorium ratios of sinking particles in the California current ecosystem 1: relationships with plankton ecosystem dynamics
We investigated variability in the C:234Th ratio of sinking particles and its relationship to changing water column characteristics and plankton ecological dynamics during 29 Lagrangian experiments conducted on six cruises of the California Current Ecosystem Long-Term Ecological Research (CCE-LTER)...
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ftcdlib:oai:escholarship.org/ark:/13030/qt47s7d1nt 2023-05-15T18:26:01+02:00 The Carbon:234Thorium ratios of sinking particles in the California current ecosystem 1: relationships with plankton ecosystem dynamics Stukel, MR Kelly, TB Aluwihare, LI Barbeau, KA Goericke, R Krause, JW Landry, MR Ohman, MD 2019-05-20 application/pdf https://escholarship.org/uc/item/47s7d1nt unknown eScholarship, University of California qt47s7d1nt https://escholarship.org/uc/item/47s7d1nt public Oceanography Other Chemical Sciences Geochemistry article 2019 ftcdlib 2021-11-08T18:16:20Z We investigated variability in the C:234Th ratio of sinking particles and its relationship to changing water column characteristics and plankton ecological dynamics during 29 Lagrangian experiments conducted on six cruises of the California Current Ecosystem Long-Term Ecological Research (CCE-LTER) Program. C:234Th ratios of sinking particles collected by a surface-tethered sediment trap (C:234ThST) varied from 2.3 to 20.5 μmol C dpm−1 over a depth range of 47–150 m. C:234ThST was significantly greater (by a factor of 1.8) than C:234Th ratios of suspended >51-μm particles collected in the same water parcels with in situ pumps. C:234Th ratios of large (>200-μm) sinking particles also exceeded those of smaller sinking particles. C:234ThST decreased with depth from the base of the euphotic zone through the upper twilight zone. C:234ThST was positively correlated with several indices of ecosystem productivity including particulate organic carbon (POC) and chlorophyll (Chl) concentrations, mesozooplankton biomass, and the fraction of Chl >20-μm. Principal component analysis and multiple linear regression suggested that decaying phytoplankton blooms exhibited higher C:234ThST than actively growing blooms at similar biomass levels. C:234ThST was positively correlated with indices of the fractional contribution of fecal pellets in sediment traps when the proportion of fecal pellets was low in the traps, likely because of a correlation between mesozooplankton biomass and other indices of ecosystem productivity. However, when fecal pellets were a more important component of sinking material, C:234ThST decreased with increasing fecal pellet content. C:234ThST was also positively correlated with the Si:C ratio of sinking particles. Across the dataset (and across depths) a strong correlation was found between C:234ThST and the ratio of vertically-integrated POC to vertically-integrated total water column 234Th (vC:234Thtot). A mechanistic one-layer, two-box model of thorium sorption and desorption was invoked to explain this correlation. Two empirical models (one using vC:234Thtot; one using depth and vertically-integrated Chl) were developed to predict C:234Th ratios in this coastal upwelling biome. The former regression (log10(C:234ThST) = 0.43 × log10(vC:234Thtot) + 0.53) was found to also be a reasonable predictor for C:234ThST from diverse regions including the Southern Ocean, Sargasso Sea, Subarctic North Pacific, and Eastern Tropical North Pacific. Article in Journal/Newspaper Southern Ocean Subarctic University of California: eScholarship Pacific Southern Ocean |
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University of California: eScholarship |
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language |
unknown |
topic |
Oceanography Other Chemical Sciences Geochemistry |
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Oceanography Other Chemical Sciences Geochemistry Stukel, MR Kelly, TB Aluwihare, LI Barbeau, KA Goericke, R Krause, JW Landry, MR Ohman, MD The Carbon:234Thorium ratios of sinking particles in the California current ecosystem 1: relationships with plankton ecosystem dynamics |
topic_facet |
Oceanography Other Chemical Sciences Geochemistry |
description |
We investigated variability in the C:234Th ratio of sinking particles and its relationship to changing water column characteristics and plankton ecological dynamics during 29 Lagrangian experiments conducted on six cruises of the California Current Ecosystem Long-Term Ecological Research (CCE-LTER) Program. C:234Th ratios of sinking particles collected by a surface-tethered sediment trap (C:234ThST) varied from 2.3 to 20.5 μmol C dpm−1 over a depth range of 47–150 m. C:234ThST was significantly greater (by a factor of 1.8) than C:234Th ratios of suspended >51-μm particles collected in the same water parcels with in situ pumps. C:234Th ratios of large (>200-μm) sinking particles also exceeded those of smaller sinking particles. C:234ThST decreased with depth from the base of the euphotic zone through the upper twilight zone. C:234ThST was positively correlated with several indices of ecosystem productivity including particulate organic carbon (POC) and chlorophyll (Chl) concentrations, mesozooplankton biomass, and the fraction of Chl >20-μm. Principal component analysis and multiple linear regression suggested that decaying phytoplankton blooms exhibited higher C:234ThST than actively growing blooms at similar biomass levels. C:234ThST was positively correlated with indices of the fractional contribution of fecal pellets in sediment traps when the proportion of fecal pellets was low in the traps, likely because of a correlation between mesozooplankton biomass and other indices of ecosystem productivity. However, when fecal pellets were a more important component of sinking material, C:234ThST decreased with increasing fecal pellet content. C:234ThST was also positively correlated with the Si:C ratio of sinking particles. Across the dataset (and across depths) a strong correlation was found between C:234ThST and the ratio of vertically-integrated POC to vertically-integrated total water column 234Th (vC:234Thtot). A mechanistic one-layer, two-box model of thorium sorption and desorption was invoked to explain this correlation. Two empirical models (one using vC:234Thtot; one using depth and vertically-integrated Chl) were developed to predict C:234Th ratios in this coastal upwelling biome. The former regression (log10(C:234ThST) = 0.43 × log10(vC:234Thtot) + 0.53) was found to also be a reasonable predictor for C:234ThST from diverse regions including the Southern Ocean, Sargasso Sea, Subarctic North Pacific, and Eastern Tropical North Pacific. |
format |
Article in Journal/Newspaper |
author |
Stukel, MR Kelly, TB Aluwihare, LI Barbeau, KA Goericke, R Krause, JW Landry, MR Ohman, MD |
author_facet |
Stukel, MR Kelly, TB Aluwihare, LI Barbeau, KA Goericke, R Krause, JW Landry, MR Ohman, MD |
author_sort |
Stukel, MR |
title |
The Carbon:234Thorium ratios of sinking particles in the California current ecosystem 1: relationships with plankton ecosystem dynamics |
title_short |
The Carbon:234Thorium ratios of sinking particles in the California current ecosystem 1: relationships with plankton ecosystem dynamics |
title_full |
The Carbon:234Thorium ratios of sinking particles in the California current ecosystem 1: relationships with plankton ecosystem dynamics |
title_fullStr |
The Carbon:234Thorium ratios of sinking particles in the California current ecosystem 1: relationships with plankton ecosystem dynamics |
title_full_unstemmed |
The Carbon:234Thorium ratios of sinking particles in the California current ecosystem 1: relationships with plankton ecosystem dynamics |
title_sort |
carbon:234thorium ratios of sinking particles in the california current ecosystem 1: relationships with plankton ecosystem dynamics |
publisher |
eScholarship, University of California |
publishDate |
2019 |
url |
https://escholarship.org/uc/item/47s7d1nt |
geographic |
Pacific Southern Ocean |
geographic_facet |
Pacific Southern Ocean |
genre |
Southern Ocean Subarctic |
genre_facet |
Southern Ocean Subarctic |
op_relation |
qt47s7d1nt https://escholarship.org/uc/item/47s7d1nt |
op_rights |
public |
_version_ |
1766207800158978048 |