Carbon Flux Explorer optical assessment of C, N and P fluxes

• Published in: Biogeosciences Vol. 16; no. 6; pp. 1249 - 1264
• Main Authors: Bourne, Hannah L, Bishop, James K. B, Wood, Todd J, Loew, Timothy J, Liu, Yizhuang
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 27-03-2019; Copernicus Publications
• Subjects: 3D printing; Additives; Air pollution; Air pollution control; Analysis; Attenuance; Calibration; California Current; Carbon; Carbon cycle; Distribution; Drifters; Ecological monitoring; Ecological research; Ecosystems; Environmental aspects; Floats; Fluctuations; Fluxes; Imagery; Imaging techniques; Lability; Nitrogen; Nitrogen cycle; Novels; Organic carbon; Organic phosphorus; Particle settling; Particulate organic carbon; Particulate organic phosphorus; Phosphorus; Phosphorus (Chemical element); Production management; Proxy; Relaying; Remineralization; Satellites; Sediment traps; Sediments (Geology); Ships; Slope; Surface water; Three dimensional printing
• ISSN: 1726-4189; 1726-4170; 1726-4189
• DOI: 10.5194/bg-16-1249-2019

The magnitude and controls of particulate carbon exported from surface waters
and its remineralization at depth are poorly constrained. The Carbon Flux
Explorer (CFE), a Lagrangian float-deployed imaging sediment trap, has been
designed to optically measure the hourly variations of particle flux to
kilometer depths for months to seasons while relaying data in near-real time
to shore via satellite without attending ships. The main optical proxy for
particle load recorded by the CFE, volume attenuance (VA; units of
mATN cm2), while rigorously defined and highly precise, has not been
robustly calibrated in terms of particulate organic carbon (POC), nitrogen
(PN) and phosphorus (PP). In this study, a novel 3-D-printed particle sampler
using cutting edge additive manufacturing was developed and integrated with
the CFE. Two such modified floats (CFE-Cals) were deployed a total of
15 times for 18–24 h periods to gain calibration imagery and samples at
depths near 150 m in four contrasting productivity environments during the
June 2017 California Current Ecosystem Long-Term Ecological Research (LTER)
process study. Regression slopes for VA : POC and VA : PN (units
mATN cm2: mmol; R2, n, p value in parentheses) were
1.01×104 (0.86, 12, < 0.001) and 1.01×105
(0.86, 15, < 0.001), respectively, and were not sensitive to
particle size classes or the contrasting environments encountered. PP was not
well correlated with VA, reflecting the high lability of P relative to C and
N. The volume attenuance flux (VAF) to POC flux calibration is compared to
previous estimates.