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Land to Ocean Transfer of Organic Carbon in the Waipaoa Sedimentary System. Hannah Brackley Landcare Research NZ Ltd. Erosion-related Carbon Losses. Poverty Bay Shelf. Organic Carbon (%). Depth (cm). Introduction.
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Land to Ocean Transfer ofOrganic Carbon in theWaipaoa Sedimentary System Hannah Brackley Landcare Research NZ Ltd
Poverty Bay Shelf Organic Carbon (%) Depth (cm) Introduction Previous research has recognised an increase in OC burial on the Waipaoa River floodplain and Poverty Bay shelf since the arrival of Europeans.
Waipaoa Sedimentary System Cores collected from: • Waipaoa River Floodplain • Poverty Bay Shelf/slope: U2303: • 7.5 km from river mouth • 27 m water depth U2305: • 22.5 km from river mouth • 56 m water depth W697: • 40 km from river mouth • 1200 m water depth
% <4 mm % 4–25 mm % >25 mm U2303 (27 m Water Depth) 1.0 6–7 cm 0.8 0.6 % OC Particle Size Distributions 0.4 0.2 100 0.0 m m m Bulk >25 m 4–25 m <4 m 80 %OC in Size Fractions 18–19 cm 3 60 Cumulative Percent 40 2 % OC 20 1 0 0 6–7 cm 18–19 cm 30–31 cm m m m Bulk >25 m 4–25 m <4 m 1.0 30–31 cm 0.8 0.6 % OC 0.4 0.2 0.0 m m m Bulk >25 m 4–25 m <4 m
U2303 (27 m Water Depth) 100 6–7 cm 80 60 Weight Percent 40 20 0 m m m > 25 m < 4 m % of Total OC in Sample 4–25 m 60 18–19 cm 50 40 30 Weight Percent 20 10 0 m m m 4–25 m > 25 m < 4 m 100 30–31 cm 80 60 Weight Percent 40 20 0 m m m > 25 m 4–25 m < 4 m
%OC as a Function of Particle Size Floodplain Mid Shelf 27 m Mid Shelf 56 m Upper Slope
d13C Trends from Floodplain to Slope d13C Floodplain Mid Shelf 27 m Mid Shelf 56 m Upper Slope
Questions • How are flood events preserved on the shelf, and how do they influence the OC? • How do changing terrestrial processes influence the amount and character of OC being transported offshore? • Are the riverine particles losing their terrestrial OC when discharged to the ocean, and if so, are they reloading with marine OC?