Detailed 230 Th, 232 Th and 210 Pb fluxes recorded by the 1989/90 BOFS sediment trap time-series at 48°N, 20°W

1995 ◽  
Vol 42 (6) ◽  
pp. 833-848 ◽  
Author(s):  
S. Colley ◽  
J. Thomson ◽  
P.P. Newton
Keyword(s):  
Radiocarbon ◽  
1996 ◽  
Vol 38 (3) ◽  
pp. 583-595 ◽  
Author(s):  
Makio C. Honda

In order to verify sediment trap samples as indicators of upper ocean 14C concentrations, particulate inorganic radiocarbon (PICΔ14C) collected by time-series sediment traps in the Sea of Okhotsk and the Bering Sea was measured by accelerator mass spectrometry (AMS). All of the PICΔ14C measurements were < 0‰, in contrast to GEOSECS 14C data in the upper ocean from the northwestern North Pacific. This difference is attributed to the upwelling of deepwater that contains low Δ14C of dissolved inorganic carbon (DICΔ14C) and to the decrease over time of surface DICΔ14C owing to the decrease of atmospheric Δ14C values. In addition, PICΔ14C values showed significant seasonal variability: PICΔ14C collected in the fall was the greatest (-22‰ on average), whereas PICΔ14C collected in winter showed an average minimum of −48‰. It is likely that this difference was caused by changes in mixed layer thickness. Although some uncertainties remain, further study on PICΔ14C will enable us to estimate seasonal variability in DICΔ14C and air-sea CO2 exchange rate.


1983 ◽  
Vol 13 (3) ◽  
pp. 181-194 ◽  
Author(s):  
Cindy Lee ◽  
Stuart G. Wakeham ◽  
John W. Farrington

Toxins ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 480 ◽  
Author(s):  
Blaire Umhau ◽  
Claudia Benitez-Nelson ◽  
Clarissa Anderson ◽  
Kelly McCabe ◽  
Christopher Burrell

Water column bulk Pseudo-nitzschia abundance and the dissolved and particulate domoic acid (DA) concentrations were measured in the Santa Barbara Basin (SBB), California from 2009–2013 and compared to bulk Pseudo-nitzschia cell abundance and DA concentrations and fluxes in sediment traps moored at 147 m and 509 m. Pseudo-nitzschia abundance throughout the study period was spatially and temporally heterogeneous (<200 cells L−1 to 3.8 × 106 cells L−1, avg. 2 × 105 ± 5 × 105 cells L−1) and did not correspond with upwelling conditions or the total DA (tDA) concentration, which was also spatially and temporally diverse (<1.3 ng L−1 to 2.2 × 105 ng L−1, avg. 7.8 × 103 ± 2.2 × 104 ng L−1). We hypothesize that the toxicity is likely driven in part by specific Pseudo-nitzschia species as well as bloom stage. Dissolved (dDA) and particulate (pDA) DA were significantly and positively correlated (p < 0.01) and both comprised major components of the total DA pool (pDA = 57 ± 35%, and dDA = 42 ± 35%) with substantial water column concentrations (>1000 cells L−1 and tDA = 200 ng L−1) measured as deep as 150 m. Our results highlight that dDA should not be ignored when examining bloom toxicity. Although water column abundance and pDA concentrations were poorly correlated with sediment trap Pseudo-nitzschia abundance and fluxes, DA toxicity is likely associated with senescent blooms that rapidly sink to the seafloor, adding another potential source of DA to benthic organisms.


1996 ◽  
Vol 67 (12) ◽  
pp. 4360-4363 ◽  
Author(s):  
K. Kremling ◽  
U. Lentz ◽  
B. Zeitzschel ◽  
D. E. Schulz‐Bull ◽  
J. C. Duinker

2015 ◽  
Vol 12 (19) ◽  
pp. 5885-5897 ◽  
Author(s):  
H. Frigstad ◽  
S. A. Henson ◽  
S. E. Hartman ◽  
A. M. Omar ◽  
E. Jeansson ◽  
...  

Abstract. In this study we present hydrography, biogeochemistry and sediment trap observations between 2003 and 2012 at Porcupine Abyssal Plain (PAP) sustained observatory in the Northeast Atlantic. The time series is valuable as it allows for investigation of the link between surface productivity and deep ocean carbon flux. The region is a perennial sink for CO2, with an average uptake of around 1.5 mmol m−2 day−1. The average monthly drawdowns of inorganic carbon and nitrogen were used to quantify the net community production (NCP) and new production. Seasonal NCP and new production were found to be 4.57 ± 0.85 mol C m−2 and 0.37 ± 0.14 mol N m−2, respectively. The C : N ratio was high (12) compared to the Redfield ratio (6.6), and the production calculated from carbon was higher than production calculated from nitrogen, which is indicative of carbon overconsumption. The export ratio and transfer efficiency were 16 and 4 %, respectively, and the site thereby showed high flux attenuation. Particle tracking was used to examine the source region of material in the sediment trap, and there was large variation in source regions, both between and within years. There were higher correlations between surface productivity and export flux when using the particle-tracking approach, than by comparing with the mean productivity in a 100 km box around the PAP site. However, the differences in correlation coefficients were not significant, and a longer time series is needed to draw conclusions on applying particle tracking in sediment trap analyses.


2015 ◽  
Vol 12 (7) ◽  
pp. 5169-5199 ◽  
Author(s):  
H. Frigstad ◽  
S. A. Henson ◽  
S. E. Hartman ◽  
A. M. Omar ◽  
E. Jeansson ◽  
...  

Abstract. In this study we present hydrography, biogeochemistry and sediment trap observations between 2003 and 2012 at Porcupine Abyssal Plain (PAP) sustained observatory in the northeast Atlantic. The time series is valuable as it allows for investigation of the link between surface productivity and deep ocean carbon flux. The region is a perennial sink for CO2, with an average uptake of around 1.5 mmol m−2 d−1. The average monthly drawdowns of inorganic carbon and nitrogen were used to quantify the net community production (NCP) and new production, respectively. Seasonal NCP and new production were found to be 4.57 ± 0.27 mol C m−2 and 0.37 ± 0.14 mol N m−2. The Redfield ratio was high (12), and the production calculated from carbon was higher than production calculated from nitrogen, which is indicative of carbon overconsumption. The export ratio and transfer efficiency were 16 and 4%, respectively, and the site thereby showed high flux attenuation. Particle tracking was used to examine the source region of material in the sediment trap, and there was large variation in source regions, both between and within years. There were higher correlations between surface productivity and export flux when using the particle-tracking approach, than by comparing with the mean productivity in a 100 km box around the PAP site. However, the differences in correlation coefficients were not significant, and a longer time series is needed to draw conclusions on applying particle tracking in sediment trap analyses.


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