scholarly journals Decadal Changes in Bomb-Produced Radiocarbon in the Pacific Ocean from the 1990s to 2000s

Radiocarbon ◽  
2013 ◽  
Vol 55 (3) ◽  
pp. 1641-1650 ◽  
Author(s):  
Yuichiro Kumamoto ◽  
Akihiko Murata ◽  
Takeshi Kawano ◽  
Shuichi Watanabe ◽  
Masao Fukasawa
Keyword(s):  
Pacific Ocean ◽  
Ocean Circulation ◽  
Dissolved Inorganic Carbon ◽  
World Ocean ◽  
Temporal Changes ◽  
Turnover Time ◽  
Subtropical Region ◽  
The North ◽  
The Pacific ◽  
The Pacific Ocean

In the 2000s, radiocarbon in dissolved inorganic carbon was measured during 7 revisit cruises along the lines of the World Ocean Circulation Experiment in the Pacific Ocean. Comparison of 14C data along these lines from the 1990s and 2000s revealed decadal changes of 14C concentration in the thermocline, most of which were due to temporal changes in the bomb-produced 14C. Vertical profiles and vertical-integrated inventories of the bomb 14C in the subarctic and equatorial regions did not change appreciably. In the southern subtropical region, 14C decreased in the upper thermocline from the surface to ∼500 m depth. In contrast, 14C increased in the lower thermocline below ∼500 m depth. The opposing directions in 14C change resulted in small temporal changes in the total inventory of bomb 14C. On the other hand, the water-column inventory significantly decreased in the northwestern subtropical region due to the 14C decrease in the upper thermocline. These decadal changes in bomb 14C indicate that the turnover time of thermocline circulation in the northwestern subtropical region is faster than that in the southern subtropical region, and imply an interbasin transport of bomb 14C from the North Pacific to other basins.

scholarly journals WOCE AMS Radiocarbon I: Pacific Ocean Results (P6, P16 and P17)

Radiocarbon ◽  
1996 ◽  
Vol 38 (3) ◽  
pp. 425-518 ◽  
Author(s):  
Robert M. Key ◽  
Paul D. Quay ◽  
Glenn A. Jones ◽  
A. P. McNichol ◽  
K. F. Von Reden ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Ocean Circulation ◽  
World Ocean ◽  
Depth Range ◽  
Near Surface ◽  
The North ◽  
The Pacific ◽  
World Ocean Circulation Experiment ◽  
The Pacific Ocean ◽  
Similar Density

AMS radiocarbon results from the World Ocean Circulation Experiment in the Pacific Ocean show dramatic changes in the inventory and distribution of bomb-produced 14C since the time of the GEOSECS survey (8/73–6/74). Near-surface Δ14C values for the eastern portion of both the northern and southern subtropical gyres decreased by 25–50‰, with the change being greater in the north. Equatorial near-surface values have increased by ca. 25‰. Changes in the 250–750-m depth range are dramatically different between the northern and southern basins. The intermediate and mode waters of the southern basin have increased by as much as 75‰ since GEOSECS. Waters of similar density in the northern hemisphere are not exposed to the Southern Ocean circulation regime and are significantly less ventilated, showing maximum changes of ca. 50‰.

scholarly journals Biogeochemistry of the North Atlantic during oceanic anoxic event 2: role of changes in ocean circulation and phosphorus input

2014 ◽  
Vol 11 (4) ◽  
pp. 977-993 ◽  
Author(s):  
I. Ruvalcaba Baroni ◽  
R. P. M. Topper ◽  
N. A. G. M. van Helmond ◽  
H. Brinkhuis ◽  
C. P. Slomp
Keyword(s):  
Pacific Ocean ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Primary Productivity ◽  
Low Oxygen ◽  
Deep Basin ◽  
The North ◽  
The Pacific ◽  
The Pacific Ocean ◽  
The North Atlantic

Abstract. The geological record provides evidence for the periodic occurrence of water column anoxia and formation of organic-rich deposits in the North Atlantic Ocean during the mid-Cretaceous (hereafter called the proto-North Atlantic). Both changes in primary productivity and oceanic circulation likely played a role in the development of the low-oxygen conditions. Several studies suggest that an increased input of phosphorus from land initiated oceanic anoxic events (OAEs). Other proposed mechanisms invoke a vigorous upwelling system and an ocean circulation pattern that acted as a trap for nutrients from the Pacific Ocean. Here, we use a detailed biogeochemical box model for the proto-North Atlantic to analyse under what conditions anoxia could have developed during OAE2 (94 Ma). The model explicitly describes the coupled water, carbon, oxygen and phosphorus cycles for the deep basin and continental shelves. In our simulations, we assume the vigorous water circulation from a recent regional ocean model study. Our model results for pre-OAE2 and OAE2 conditions are compared to sediment records of organic carbon and proxies for photic zone euxinia and bottom water redox conditions (e.g. isorenieratane, carbon/phosphorus ratios). Our results show that a strongly elevated input of phosphorus from rivers and the Pacific Ocean relative to pre-OAE2 conditions is a requirement for the widespread development of low oxygen in the proto-North Atlantic during OAE2. Moreover, anoxia in the proto-North Atlantic is shown to be greatly influenced by the oxygen concentration of Pacific bottom waters. In our model, primary productivity increased significantly upon the transition from pre-OAE2 to OAE2 conditions. Our model captures the regional trends in anoxia as deduced from observations, with euxinia spreading to the northern and eastern shelves but with the most intense euxinia occurring along the southern coast. However, anoxia in the central deep basin is difficult to achieve in the model. This suggests that the ocean circulation used in the model may be too vigorous and/or that anoxia in the proto-North Atlantic was less widespread than previously thought.

Recent Bottom Water Warming in the Pacific Ocean*

2007 ◽  
Vol 20 (21) ◽  
pp. 5365-5375 ◽  
Author(s):  
Gregory C. Johnson ◽  
Sabine Mecking ◽  
Bernadette M. Sloyan ◽  
Susan E. Wijffels
Keyword(s):  
Pacific Ocean ◽  
Bottom Water ◽  
World Ocean ◽  
Heat Content ◽  
Temperature Changes ◽  
The North ◽  
Time Period ◽  
The Pacific ◽  
The Pacific Ocean ◽  
The North Pacific

Abstract Decadal changes of abyssal temperature in the Pacific Ocean are analyzed using high-quality, full-depth hydrographic sections, each occupied at least twice between 1984 and 2006. The deep warming found over this time period agrees with previous analyses. The analysis presented here suggests it may have occurred after 1991, at least in the North Pacific. Mean temperature changes for the three zonal and three meridional hydrographic sections analyzed here exhibit abyssal warming often significantly different from zero at 95% confidence limits for this time period. Warming rates are generally larger to the south, and smaller to the north. This pattern is consistent with changes being attenuated with distance from the source of bottom water for the Pacific Ocean, which enters the main deep basins of this ocean southeast of New Zealand. Rough estimates of the change in ocean heat content suggest that the abyssal warming may amount to a significant fraction of upper World Ocean heat gain over the past few decades.

scholarly journals Phosphate monoesterase and diesterase activities in the North and South Pacific Ocean

2013 ◽  
Vol 10 (6) ◽  
pp. 10095-10124 ◽  
Author(s):  
M. Sato ◽  
R. Sakuraba ◽  
F. Hashihama
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
Western North Pacific ◽  
Biogeochemical Cycling ◽  
Turnover Time ◽  
The North ◽  
South Pacific Ocean ◽  
The Pacific ◽  
The Pacific Ocean ◽  
North And South

Abstract. To reveal the biogeochemical cycling of phosphorus in the Pacific Ocean, phosphate monoesterase and diesterase activities were measured with soluble reactive phosphorus (SRP) and labile and total dissolved organic phosphorus (DOP) concentrations in the North and South Pacific Ocean. Both esterase activities were noticeably enhanced around the western part of 30° N, where the surface SRP concentration was below 10 nM, while they showed no significant correlation with DOP concentration. The proportion of the activity in the dissolved fraction was higher for diesterase than monoesterase, which may support results from previous genomic analyses. Substrate affinity and the maximum hydrolysis rate of monoesterase were the highest at lower concentrations of SRP, showing the adaptation of microbes to inorganic phosphorus nutrient deficiency at the molecular level. The calculated turnover time of monoesters was 1 to 2 weeks in the western North Pacific Ocean, which was much shorter than the turnover time in other areas of the Pacific Ocean but longer than the turnover time in other phosphate-depleted areas. In contrast, the turnover rate of diesters was calculated to exceed 100 days, revealing that diesters in the western North Pacific were a biologically refractory phosphorus fraction. In future studies, a combination of molecular biological techniques and kinetic studies will reveal the entire process of biogeochemical cycling of phosphorus in the ocean, including components that were not elucidated in the present study.

scholarly journals Woce Radiocarbon IV: Pacific Ocean Results; P10, P13N, P14C, P18, P19 & S4P

Radiocarbon ◽  
2002 ◽  
Vol 44 (1) ◽  
pp. 239-392 ◽  
Author(s):  
Robert M Key ◽  
Paul D Quay ◽  
Peter Schlosser ◽  
A P McNichol ◽  
KF von Reden ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Ocean Circulation ◽  
Large Scale ◽  
World Ocean ◽  
Mass Spectrometry Analysis ◽  
Data Set ◽  
Spectrometry Analysis ◽  
The Pacific ◽  
World Ocean Circulation Experiment ◽  
The Pacific Ocean

The World Ocean Circulation Experiment, carried out between 1990 and 1997, provided the most comprehensive oceanic survey of radiocarbon to date. Approximately 10,000 samples were collected in the Pacific Ocean by U.S. investigators for both conventional large volume p counting and small volume accelerator mass spectrometry analysis techniques. Results from six cruises are presented. The data quality is as good or better than previous large-scale surveys. The 14C distribution for the entire WOCE Pacific data set is graphically described using mean vertical profiles and sections, and property-property plots.

scholarly journals Phosphate monoesterase and diesterase activities in the North and South Pacific Ocean

2013 ◽  
Vol 10 (11) ◽  
pp. 7677-7688 ◽  
Author(s):  
M. Sato ◽  
R. Sakuraba ◽  
F. Hashihama
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
Western North Pacific ◽  
South Pacific ◽  
Turnover Time ◽  
The North ◽  
South Pacific Ocean ◽  
The Pacific ◽  
The Pacific Ocean ◽  
North And South

Abstract. Phosphate monoesterase and diesterase activities were measured with soluble reactive phosphorus (SRP) and labile and total dissolved organic phosphorus (DOP) concentrations in the North and South Pacific Ocean, to reveal the microbial utilization of phosphate esters in the Pacific Ocean. Both esterase activities were noticeably enhanced around the western part of 30° N, where the surface SRP concentration was below 10 nM, while they showed no significant correlation with DOP concentration. The proportion of the activity in the dissolved fraction was higher for diesterase than monoesterase, which may support results from previous genomic analyses. Substrate affinity and the maximum hydrolysis rate of monoesterase were the highest at lower concentrations of SRP, showing the adaptation of microbes to inorganic phosphorus nutrient deficiency at the molecular level. The calculated turnover time of monoesters was 1 to 2 weeks in the western North Pacific Ocean, which was much shorter than the turnover time in other areas of the Pacific Ocean but longer than the turnover time in other phosphate-depleted areas. In contrast, the turnover rate of diesters was calculated to exceed 100 days, revealing that diesters in the western North Pacific were a biologically refractory phosphorus fraction. In the present study, it was revealed that both phosphate monoesters and diesters can be a phosphorus source for microbes in the phosphate-depleted waters, although the dynamics of the two esters are totally different.

IX. Contributions to terrestrial magnetism.—No. IV

1843 ◽  
Vol 133 ◽  
pp. 113-143 ◽  
Keyword(s):  
Pacific Ocean ◽  
West Coast ◽  
China Seas ◽  
North West ◽  
The North ◽  
The Pacific ◽  
The Pacific Ocean ◽  
The Times ◽  
The China Seas

In the present number of these Contributions, I resume the consideration of Captain Sir Edward Belcher’s magnetic observations, of which the first portion, viz. that of the stations on the north-west coast of America and adjacent islands, was discussed in No. II. The return to England of Her Majesty’s ship Sulphur by the route of the Pacific Ocean, and her detention for some months in the China Seas, have enabled Sir Edward Belcher to add magnetic determinations at thirty-two stations to those at the twenty-nine stations previously recorded. In the notice of the earlier observations, a provisional coefficient was employed in the formula for the temperature corrections of the results with the intensity needles, as no experiments had then been made for the determination of their individual co­efficients. As soon therefore as Sir Edward Belcher had completed the observation of the times of vibration of those needles at Woolwich, as the concluding station of the series made with them, Lieut. Riddell, R. A. undertook the determination of their several coefficients, which was performed in the manner and with the results described in the subjoined memorandum.

Sign in / Sign up

Export Citation Format

Share Document