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Abstract Sinking particles strongly regulate the distribution of reactive chemical substances in the ocean, including particulate organic carbon and other elements (e.g., P, Cd, Mn, Cu, Co, Fe, Al, and232Th). Yet, the sinking fluxes of trace elements have not been well described in the global ocean. The U.S. GEOTRACES campaign in the North Atlantic (GA03) offers the first data set in which the sinking flux of carbon and trace elements can be derived using four different radionuclide pairs (238U:234Th;210Pb:210Po;228Ra:228Th; and234U:230Th) at stations co‐located with sediment trap fluxes for comparison. Particulate organic carbon, particulate P, and particulate Cd fluxes all decrease sharply with depth below the euphotic zone. Particulate Mn, Cu, and Co flux profiles display mixed behavior, some cases reflecting biotic remineralization, and other cases showing increased flux with depth. The latter may be related to either lateral input of lithogenic material or increased scavenging onto particles. Lastly, particulate Fe fluxes resemble fluxes of Al and232Th, which all have increasing flux with depth, indicating a dominance of lithogenic flux at depth by resuspended sediment transported laterally to the study site. In comparing flux estimates derived using different isotope pairs, differences result from different timescales of integration and particle size fractionation effects. The range in flux estimates produced by different methods provides a robust constraint on the true removal fluxes, taking into consideration the independent uncertainties associated with each method. These estimates will be valuable targets for biogeochemical modeling and may also offer insight into particle sinking processes.
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This content will become publicly available on October 1, 2026
GelCam : Visualizing sinking particle flux via a polyacrylamide gel‐based sediment trap
Sinking particles play a key role in the biological carbon pump. While previous studies have analyzed particulate carbon flux over timescales of days to years, few have been able to resolve flux variability on shorter, hourly scales at multiple depths simultaneously. This study uses an array of upward‐facing cameras, built from off‐the‐shelf components for under $500 each, to visualize particle fluxes at multiple depths during the EXPORTS campaign in 2018 in the North Pacific. This manuscript is the first comprehensive description of this tool, called GelCam, which captures a time‐lapse image sequence at 20‐min intervals of particles that settle into a polyacrylamide gel layer located at the base of a sediment trap tube. Methods are described for the design and post‐processing pipeline, in addition to two proxy methods for estimating the total particulate organic carbon flux. The GelCam‐derived fluxes modeled from individual particle images show strong agreement with the ground‐truth data obtained from coincident trap measurements. This approach helps address the need for accessible, open‐source tools to more broadly observe and quantify the role of episodic particle flux events across the global oceans.
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- PAR ID:
- 10660075
- Publisher / Repository:
- NASA's SeaBASS archive at https://oceandata.sci.gsfc.nasa.gov/ob/getfile/dd2fe323be_EXPORTS-EXPORTSNP_RR1813_GelCam_20180814-20180909_R1.sb and https://oceandata.sci.gsfc.nasa.gov/ob/getfile/8a0152ccab_EXPORTS-EXPORTSNA_JC214_GelCam_20210504-20210509_R1.sb.
- Date Published:
- Journal Name:
- Limnology and Oceanography: Methods
- Volume:
- 23
- Issue:
- 10
- ISSN:
- 1541-5856
- Page Range / eLocation ID:
- 715 to 728
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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