scholarly journals Terrestrial exports of dissolved and particulate organic carbon affect nearshore ecosystems of the Pacific coastal temperate rainforest

2020 ◽  
Vol 65 (11) ◽  
pp. 2657-2675
Author(s):  
Kyra A. St. Pierre ◽  
Allison A. Oliver ◽  
Suzanne E. Tank ◽  
Brian P. V. Hunt ◽  
Ian Giesbrecht ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Temperate Rainforest ◽  
Nearshore Ecosystems ◽  
The Pacific

scholarly journals Distribution, fluxes and balance of particulate organic carbon in the Arctic ocean

2019 ◽  
Vol 59 (4) ◽  
pp. 544-552
Author(s):  
A. A. Vetrov ◽  
E. A. Romankevich
Keyword(s):  
Organic Carbon ◽  
Arctic Ocean ◽  
Particulate Organic Carbon ◽  
The Arctic ◽  
Climate Data ◽  
Arctic Seas ◽  
The Pacific ◽  
The Arctic Ocean ◽  
Main Component ◽  
Depth Horizon

Particulate organic carbon (POC) is one of main component of carbon cycle in the Ocean. In this study an attempt to construct a picture of the distribution and fluxes of POC in the Arctic Ocean adjusting for interchange with the Pacific and Atlantic Oceans has been made. The specificity of this construction is associated with an irregular distribution of POC measurements and complicated structure and hydrodynamics of the waters masses. To overcome these difficulties, Multiple Linear Regression technic (MLR) was performed to test the significant relation between POC, temperature, salinity, as well depth, horizon, latitude and offshore distance. The mapping of POC distribution and its fluxes was carrying out at 38 horizons from 5 to 4150 m (resolution 1°×1°). Data on temperature, salinity, meridional and zonal components of current velocities were obtained from ORA S4 database (Integrated Climate Data Center, http://icdc.cen.uni-hamburg.de/las). The import-export of POC between the Arctic, Atlantic and Pacific Oceans as well as between Arctic Seas was precomputed by summer fluxes. The import of POC in the Arctic Ocean is estimated to be 38±8Tg Cyr-1, and the export is -9.5±4.4Tg Cyr-1.

scholarly journals Globally significant yields of dissolved organic carbon from small watersheds of the Pacific coastal temperate rainforest

2017 ◽  
Author(s):  
Allison A. Oliver ◽  
Suzanne E. Tank ◽  
Ian Giesbrecht ◽  
Maartje C. Korver ◽  
William C. Floyd ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Stream Water ◽  
Coastal Ocean ◽  
Temperate Rainforest ◽  
The Pacific ◽  
Doc Concentration ◽  
Small Catchments ◽  
Outer Coast ◽  
Dom Composition

Abstract. The perhumid region of the Pacific coastal temperate rainforest of North America (PCTR) is one of the wettest places on Earth and contains numerous small catchments that discharge freshwater and high concentrations of dissolved organic carbon (DOC) directly to the coastal ocean. However, empirical data on the flux and composition of DOC exported from these watersheds is scarce. We established monitoring stations at the outlets of seven catchments on Calvert and Hecate Islands, British Columbia, which represent the rain dominated outer-coast region of the PCTR. Over several years, we measured stream discharge, stream water DOC concentration, and stream water dissolved organic matter (DOM) composition. Discharge and DOC concentrations were used to calculate DOC fluxes and yields, and DOM composition was examined using absorbance and fluorescence spectroscopy, including parallel factor analysis (PARAFAC). The areal estimate of annual DOC yield in water year 2015 was 33.3 Mg C km−2 yr−1, with individual watersheds ranging from an average of 24.1–37.7 Mg C km−2 yr−1. This represents some of the highest DOC yields in the world exported to the ocean. We observed strong seasonality in the quantity and composition of exports, with the majority of DOC export occurring during the extended wet period of the year (September–April). Stream flow from catchments reacted quickly to rain inputs, resulting in rapid flushing of relatively fresh, highly terrestrial-like DOM. DOC concentration and measures of DOM composition were correlated with watershed attributes, including the extent of lakes and wetlands, and thickness of organic and mineral soils. Our discovery of high DOC yields from these small catchments on the outer-coast of the temperate rainforest is especially compelling as they represent the delivery of relatively fresh, highly terrestrial organic matter directly to the coastal ocean. This suggests that this coastal margin may play an important role in the global processing of carbon and in linking terrestrial carbon to marine ecosystems.

The Carbon:²³⁴Thorium ratios of sinking particles in the California Current Ecosystem 2: Examination of a thorium sorption, desorption, and particle transport model

2019 ◽  
Author(s):  
Michael Stukel ◽  
Thomas Kelly
Keyword(s):  
Organic Carbon ◽  
Water Column ◽  
Particulate Organic Carbon ◽  
Transport Model ◽  
California Current ◽  
In Situ Measurements ◽  
Power Law Distribution ◽  
Sinking Particles ◽  
Organic Carbon Concentration

Thorium-234 (234Th) is a powerful tracer of particle dynamics and the biological pump in the surface ocean; however, variability in carbon:thorium ratios of sinking particles adds substantial uncertainty to estimates of organic carbon export. We coupled a mechanistic thorium sorption and desorption model to a one-dimensional particle sinking model that uses realistic particle settling velocity spectra. The model generates estimates of 238U-234Th disequilibrium, particulate organic carbon concentration, and the C:234Th ratio of sinking particles, which are then compared to in situ measurements from quasi-Lagrangian studies conducted on six cruises in the California Current Ecosystem. Broad patterns observed in in situ measurements, including decreasing C:234Th ratios with depth and a strong correlation between sinking C:234Th and the ratio of vertically-integrated particulate organic carbon (POC) to vertically-integrated total water column 234Th, were accurately recovered by models assuming either a power law distribution of sinking speeds or a double log normal distribution of sinking speeds. Simulations suggested that the observed decrease in C:234Th with depth may be driven by preferential remineralization of carbon by particle-attached microbes. However, an alternate model structure featuring complete consumption and/or disaggregation of particles by mesozooplankton (e.g. no preferential remineralization of carbon) was also able to simulate decreasing C:234Th with depth (although the decrease was weaker), driven by 234Th adsorption onto slowly sinking particles. Model results also suggest that during bloom decays C:234Th ratios of sinking particles should be higher than expected (based on contemporaneous water column POC), because high settling velocities minimize carbon remineralization during sinking.

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