scholarly journals Land to Ocean Transfer of Erosion-Related Organic Carbon, Waipaoa Sedimentary System, East Coast, New Zealand

2021 ◽  
Author(s):  
◽  
Hannah Lema Brackley
Keyword(s):  
New Zealand ◽  
Organic Carbon ◽  
Continental Shelf ◽  
Continental Slope ◽  
East Coast ◽  
Thick Layer ◽  
Terrestrial Source ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Floodplain Sediments

<p>Mountainous islands of the Pacific Rim (such as New Zealand) purportedly deliver up to 40% of the suspended sediment load and up to 35% of the riverine particulate organic carbon (POC) load to the world's oceans. On the east coast of New Zealand's North Island, the Waipaoa River drains a steep, 2205 km2 catchment located on the active collisional East Coast Continental Margin. It has an annual suspended sediment load of 15 Tg (15 x 1012 g), making up ~7% of New Zealand's total yield to the Pacific Ocean, and a mean annual POC discharge to the Pacific Ocean of 86.7 Gg (86.7 x 109 g). The annual loss of OC to the floodplain is ~9% of this annual POC discharge (~7.8 Gg). A range of analyses (including organic carbon content (%OC), stable carbon isotopes (Delta 13C), radiocarbon (14C), carbon to nitrogen ratios (C/N)a and carbon loadings (OC:SA)) were performed on correlative sediments from a transect of 7 cores from depositional sites located on the Waipaoa River floodplain and adjacent continental shelf and slope. Results were used to determine biogeochemical characteristics of organic carbon (OC) at a range of depositional sites during its transfer from terrestrial source to marine sink, and how large floods impact OC transfer to the marine environment. The high temporal variability in OC content (0.2 to 3.5%) and different source signatures (Delta 13C of -26.7 to -20.6% degrees) of Waipaoa River floodplain deposits prevented the establishment of a clear benchmark signature for flood deposits that may be recognisable in the marine sedimentary record. The high spatial and temporal variability of floodplain sediment OC, combined with the areal extent of floodplains within the catchment, indicates the appreciable modulating effect the floodplain has on OC transfers to the ocean. Since extensive stopbanks were constructed on the main floodplain since the 1940' s, sequestration of OC in floodplain sediments has reduced by about half, increasing the overall efficiency of the Waipaoa River in transferring terrestrial OC directly to the marine environment.  Flood layers are preserved in the marine sedimentary record. Continental shelf sediments indicate that during Cyclone Bola (March 1988, a rainfall event with a >100 year return period), the extreme river discharge produced a hyperpycnal (negatively buoyant) plume, preserved as a ~10 cm thick layer on the inner shelf and a ~1 cm thick layer on the mid-shelf. The flood layer contains a significant amount of terrestrially-sourced OC (up to 86% of total OC in >25 Mu m fraction) which subsequently was rapidly buried by normal marine deposits (in which ~60% of OC in >25 Mu m fraction is terrestrial), thereby preserving its strong terrestrial source signature. As sediments are physically and biologically processed at various depositional sites across the continental shelf and slope, they lose some of their modern terrestrial OC, and the concurrent addition of marine sourced OC results in the sediments gaining a stronger marine biogeochemical signature (Delta 13C values increasing from -26.2% degrees for floodplain sediments to -21.6% degrees for upper continental slope sediments). Carbon loading (OC:SA) and 14C data revealed the contributions of kerogen, modern terrestrial OC and modern marine OC to the total OC of continental shelf and slope surface sediments. Sediments retain about 40% of their terrestrial OC following transport to the continental slope, of which a significant amount consists of kerogen. Because of high erosion rates within the catchment, kerogen associated with the particles escapes oxidation, and therefore makes up a large part of the POC flux. Kerogen is preserved across the margin to the mid-slope, where only 8% of the bulk sediment OC consists of modern terrestrial OC, 58% is modern marine OC and 34% is kerogen. Biomarker analyses of surface samples also support findings that terrestrial OC is being transferred across the continental margin, with plant sterols, long chain alcohols and long chain fatty acids (biomarkers indicative of vascular plants) persisting as far offshore as the mid-continental slope. Results presented verify and add to the understanding of OC transfers and transformations at a range of depositional sites from terrestrial source to marine sink. This study provides the first quantitative assessment of land to ocean OC transfers from New Zealand. These findings, together with information on sediment budgets and depositional rates of OC in terrestrial and marine depositional environments, could provide a vital step toward establishing global OC budgets for small mountainous island environments.</p>

scholarly journals Land to Ocean Transfer of Erosion-Related Organic Carbon, Waipaoa Sedimentary System, East Coast, New Zealand

2021 ◽  
Author(s):  
◽  
Hannah Lema Brackley
Keyword(s):  
New Zealand ◽  
Organic Carbon ◽  
Continental Shelf ◽  
Continental Slope ◽  
East Coast ◽  
Thick Layer ◽  
Terrestrial Source ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Floodplain Sediments

<p>Mountainous islands of the Pacific Rim (such as New Zealand) purportedly deliver up to 40% of the suspended sediment load and up to 35% of the riverine particulate organic carbon (POC) load to the world's oceans. On the east coast of New Zealand's North Island, the Waipaoa River drains a steep, 2205 km2 catchment located on the active collisional East Coast Continental Margin. It has an annual suspended sediment load of 15 Tg (15 x 1012 g), making up ~7% of New Zealand's total yield to the Pacific Ocean, and a mean annual POC discharge to the Pacific Ocean of 86.7 Gg (86.7 x 109 g). The annual loss of OC to the floodplain is ~9% of this annual POC discharge (~7.8 Gg). A range of analyses (including organic carbon content (%OC), stable carbon isotopes (Delta 13C), radiocarbon (14C), carbon to nitrogen ratios (C/N)a and carbon loadings (OC:SA)) were performed on correlative sediments from a transect of 7 cores from depositional sites located on the Waipaoa River floodplain and adjacent continental shelf and slope. Results were used to determine biogeochemical characteristics of organic carbon (OC) at a range of depositional sites during its transfer from terrestrial source to marine sink, and how large floods impact OC transfer to the marine environment. The high temporal variability in OC content (0.2 to 3.5%) and different source signatures (Delta 13C of -26.7 to -20.6% degrees) of Waipaoa River floodplain deposits prevented the establishment of a clear benchmark signature for flood deposits that may be recognisable in the marine sedimentary record. The high spatial and temporal variability of floodplain sediment OC, combined with the areal extent of floodplains within the catchment, indicates the appreciable modulating effect the floodplain has on OC transfers to the ocean. Since extensive stopbanks were constructed on the main floodplain since the 1940' s, sequestration of OC in floodplain sediments has reduced by about half, increasing the overall efficiency of the Waipaoa River in transferring terrestrial OC directly to the marine environment.  Flood layers are preserved in the marine sedimentary record. Continental shelf sediments indicate that during Cyclone Bola (March 1988, a rainfall event with a >100 year return period), the extreme river discharge produced a hyperpycnal (negatively buoyant) plume, preserved as a ~10 cm thick layer on the inner shelf and a ~1 cm thick layer on the mid-shelf. The flood layer contains a significant amount of terrestrially-sourced OC (up to 86% of total OC in >25 Mu m fraction) which subsequently was rapidly buried by normal marine deposits (in which ~60% of OC in >25 Mu m fraction is terrestrial), thereby preserving its strong terrestrial source signature. As sediments are physically and biologically processed at various depositional sites across the continental shelf and slope, they lose some of their modern terrestrial OC, and the concurrent addition of marine sourced OC results in the sediments gaining a stronger marine biogeochemical signature (Delta 13C values increasing from -26.2% degrees for floodplain sediments to -21.6% degrees for upper continental slope sediments). Carbon loading (OC:SA) and 14C data revealed the contributions of kerogen, modern terrestrial OC and modern marine OC to the total OC of continental shelf and slope surface sediments. Sediments retain about 40% of their terrestrial OC following transport to the continental slope, of which a significant amount consists of kerogen. Because of high erosion rates within the catchment, kerogen associated with the particles escapes oxidation, and therefore makes up a large part of the POC flux. Kerogen is preserved across the margin to the mid-slope, where only 8% of the bulk sediment OC consists of modern terrestrial OC, 58% is modern marine OC and 34% is kerogen. Biomarker analyses of surface samples also support findings that terrestrial OC is being transferred across the continental margin, with plant sterols, long chain alcohols and long chain fatty acids (biomarkers indicative of vascular plants) persisting as far offshore as the mid-continental slope. Results presented verify and add to the understanding of OC transfers and transformations at a range of depositional sites from terrestrial source to marine sink. This study provides the first quantitative assessment of land to ocean OC transfers from New Zealand. These findings, together with information on sediment budgets and depositional rates of OC in terrestrial and marine depositional environments, could provide a vital step toward establishing global OC budgets for small mountainous island environments.</p>

The Recent Cypraeidae of Northern New Zealand from the Kermadec Islands to the Poor Knights Islands, Southwest Pacific Ocean (Mollusca: Gastropoda: Cypraeidae)

The Festivus ◽  
2018 ◽  
Vol 50 (1) ◽  
pp. 36-54
Author(s):  
John Daughenbaugh
Keyword(s):  
New Zealand ◽  
Pacific Ocean ◽  
Continental Shelf ◽  
East Coast ◽  
Species Distributions ◽  
East Side ◽  
Tropical Eastern Pacific ◽  
The North ◽  
The Poor ◽  
Coastal Shelf

For researchers, isolated regions at the periphery of species’ distributions hold a peculiar fascination. The causes of their remoteness vary based on: distance (e.g. the Tropical Eastern Pacific), distance and countervailing currents (e.g. the Marquesas), location in a present day gyre (e.g. the Pitcairn Group) or the absence of present day means of veliger transport (e.g. the Vema Seamount). (Daughenbaugh & Beals 2013; Daughenbaugh 2015a & b, 2017). The northern New Zealand Region from the Kermadec Islands (Kermadecs) to the coastal and shelf areas in the northernmost part of New Zealand’s North Island (Northland), including the Poor Knights Islands (PKI), constitute the distributional boundaries for a number of Cypraeidae species. The boundaries are the result of the absence of coastal shelves along the east side of the Kermadec Ridge (Ridge) and precipitous drops to abyssal depths along Northland’s east coast continental shelf. Tropical waters, with their potential to transport Cypraeidae larvae, flow eastward from southern Queensland, Australia, entrained in the Tasman Front which terminates when reaching North Cape, the northernmost tip of Northland. There, the North Cape Eddy captures most of this flow while the remainder, the East Auckland Current (EAUC), flows intermittently southward along the eastern coastal, shelf and offshore areas of Northland into waters incapable of supporting Cypraeidae populations.

The Pacific Ocean as Highway to Gold Mountain

2017 ◽  
Author(s):  
Elizabeth Sinn
Keyword(s):  
United States ◽  
New Zealand ◽  
Pacific Ocean ◽  
Capital Flows ◽  
The United States ◽  
The West ◽  
New Era ◽  
The Pacific ◽  
History Of ◽  
The Pacific Ocean

This chapter takes a broad look at the Pacific Ocean in relation to Chinese migration. As trade, consumption and capital flows followed migrants, powerful networks were woven and sustained; in time, the networks fanned across the Pacific from British Columbia along the West Coast of the United States to New Zealand and Australia. The overlapping personal, family, financial and commercial interests of Chinese in California and those in Hong Kong, which provide the focus of this study, energized the connections and kept the Pacific busy and dynamic while shaping the development of regions far beyond its shores. The ocean turned into a highway for Chinese seeking Gold Mountain, marking a new era in the history of South China, California, and the Pacific Ocean itself.

scholarly journals Response of export production and dissolved oxygen concentrations in oxygen minimum zones to <i>p</i>CO<sub>2</sub> and temperature stabilization scenarios in the biogeochemical model HAMOCC 2.0

2017 ◽  
Vol 14 (4) ◽  
pp. 781-797 ◽  
Author(s):  
Teresa Beaty ◽  
Christoph Heinze ◽  
Taylor Hughlett ◽  
Arne M. E. Winguth
Keyword(s):  
Pacific Ocean ◽  
Organic Carbon ◽  
Dissolved Oxygen ◽  
Radiative Forcing ◽  
The Pacific ◽  
Poc Flux ◽  
Poc Export ◽  
The Pacific Ocean ◽  
Do Concentration ◽  
Oxygen Minimum

Abstract. Dissolved oxygen (DO) concentration in the ocean is an important component of marine biogeochemical cycles and will be greatly altered as climate change persists. In this study a global oceanic carbon cycle model (HAMOCC 2.0) is used to address how mechanisms of oxygen minimum zone (OMZ) expansion respond to changes in CO2 radiative forcing. Atmospheric pCO2 is increased at a rate of 1 % annually and the model is stabilized at 2 ×, 4 ×, 6  ×, and 8 × preindustrial pCO2 levels. With an increase in CO2 radiative forcing, the OMZ in the Pacific Ocean is controlled largely by changes in particulate organic carbon (POC) export, resulting in increased remineralization and thus expanding the OMZs within the tropical Pacific Ocean. A potential decline in primary producers in the future as a result of environmental stress due to ocean warming and acidification could lead to a substantial reduction in POC export production, vertical POC flux, and thus increased DO concentration particularly in the Pacific Ocean at a depth of 600–800 m. In contrast, the vertical expansion of the OMZs within the Atlantic is linked to increases POC flux as well as changes in oxygen solubility with increasing seawater temperature. Changes in total organic carbon and increase sea surface temperature (SST) also lead to the formation of a new OMZ in the western subtropical Pacific Ocean. The development of the new OMZ results in dissolved oxygen concentration of  ≤  50 µmol kg−1 throughout the equatorial Pacific Ocean at 4 times preindustrial pCO2. Total ocean volume with dissolved oxygen concentrations of  ≤  50 µmol kg−1 increases by 2.4, 5.0, and 10.5 % for the 2 ×, 4 ×, and 8 × CO2 simulations, respectively.

Correlation of 210Pb removal with organic carbon fluxes in the Pacific Ocean

Nature ◽  
1988 ◽  
Vol 331 (6154) ◽  
pp. 339-341 ◽  
Author(s):  
Willard S. Moore ◽  
Jack Dymondt
Keyword(s):  
Pacific Ocean ◽  
Organic Carbon ◽  
Carbon Fluxes ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Organic Carbon Fluxes

Oxygen Utilization and Organic Carbon Remineralization in the Upper Water Column of the Pacific Ocean

2004 ◽  
Vol 60 (1) ◽  
pp. 45-52 ◽  
Author(s):  
Richard A. Feely ◽  
Christopher L. Sabine ◽  
Reiner Schlitzer ◽  
John L. Bullister ◽  
Sabine Mecking ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Organic Carbon ◽  
Water Column ◽  
Oxygen Utilization ◽  
The Pacific ◽  
Carbon Remineralization ◽  
The Pacific Ocean

scholarly journals The Development and Application of a New High Precision GC-IRMS Technique for N2O-Free Isotopic Analysis of Atmospheric CO2

2021 ◽  
Author(s):  
◽  
Dominic Francesco Ferretti
Keyword(s):  
New Zealand ◽  
Ambient Pressure ◽  
Atmospheric Co2 ◽  
Mixing Ratio ◽  
Air Samples ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Measurement Uncertainties ◽  
Initial Results ◽  
Cape Grim

<p>A new GC-IRMS technique has been developed for isotopic and mixing ratio analysis of atmospheric CO2. The technique offers for the first time, N2O-free, high precision (<0.05 [per mil]) analysis of d13C and d18O from small whole-air samples. On-line GC separation of CO2 and N2O from these small samples is combined with IRMS under elevated ion source pressures. A specialised open split interface is an integral part of the inlet system and ensures a continuous flow of either sample gas or pure helium to the IRMS. The analysis, including all flushing, uses a total of 45 ml of an air sample collected at ambient pressure. Of this, three 0.5 ml aliquots are injected onto the GC column, each providing [approximately] 0.8 nmol CO2 in the IRMS source. At this sample size, d13C precision obtained is at the theoretical shot-noise limit. Demonstrated precisions for d13C, d18O, and CO2 mixing ratio (all measured simultaneously)are 0.02 [per mil], 0.04 [per mil] and 0.4 ppm respectively. The initial results from an inter calibration exercise with Atmospheric Research at the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia achieved the International Atomic Energy Agency (IAEA) target precision for d13C. During this exercise, agreement for d18O and CO2 mixing ratio was outside the IAEA and World Meteorological Organization (WMO) target precisions for these species, however, when the measurement uncertainties of the two laboratories were considered, the differences were not significant. An inter comparison program using air samples collected at Baring Head, New Zealand and Cape Grim, Australia was also established with CSIRO and d13C, d18O and CO2 mixing ratio showed excellent agreement when combined measurement uncertainties were considered. Further inter comparisons with the Carbon Cycle Group at the National Oceanic and Atmospheric Administration Climate Monitoring and Diagnostics Laboratory (NOAA CMDL), the Institute of Arctic and Alpine Research (INSTAAR), and Scripps Institution of Oceanography (SIO) were also established. No significant differences for d13C were observed during these inter comparison programs. Therefore, these preliminary measurements suggest that the current situation between these laboratories for d13C comparisons from whole-air in glass flasks may be improved compared to the 1995 IAEA inter comparison from whole-air in high-pressure cylinders. Following these inter calibration and inter comparison exercises, temporal and spatial variations in the mixing ratio and isotopic composition of atmospheric CO2 were determined over a large region of the Pacific Ocean to demonstrate the successful use of the GC-IRMS technique. Temporal variations were observed at long-term monitoring sites in the Southern Hemisphere (Baring Head, Cape Grim, and Arrival Heights, Ross Island, Antarctica). Seasonal cycles of CO2 mixing ratio and d13C, with amplitudes of [approximately] 1 ppm and [approximately] 0.05 [per mil] respectively, were measured at Baring Head. A decline in d13C of [approximately] -0.1 [per mil]/year was observed at Arrival Heights between 1997 and 1999. Spatial variations in the Pacific Ocean were investigated by shipboard sampling programs between [approximately] 62 degrees S and [approximately] 32 degrees N. These data were consistent with a Southern Ocean sink between [approximately] 43 degrees S and [approximately] 57 degrees S. In addition, inter hemispheric gradients of d13C and CO2 mixing ratio in March and September 1998 were determined and the position and intensity of the SPCZ and ITCZ were important for the strength of these inter hemispheric gradients. Measurements performed during an upper tropospheric flight from New Zealand, to Antarctica show elevated CO2 levels and depleted d13C compared to samples obtained in the marine boundary layer over this region. A small-scale application of the technique measured soil-respired CO2 in a New Zealand Mountain Beech forest from 150 ml sample flasks that were filled to ambient pressure. These measurements determined a difference between the d13C source signature from the young and old trees of [approximately] 0.3 [per mil], which was in the correct direction but of smaller magnitude than that expected. The small sample requirements of the GC-IRMS technique ease sample collection logistics for varied research. Since initial results from an inter calibration exercise with CSIRO obtain the IAEA target precision for d13C and the technique has demonstrated its ability to successfully monitor atmospheric CO2 species from small whole-air samples, without contamination by atmospheric N2O or the use of cryogen, the technique will be a powerful tool in global carbon cycle research.</p>

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