Determining true particulate organic carbon: bottles, pumps and methodologies

Gardner, Wilford D.; Richardson, Mary Jo; Carlson, Craig A.; Hansell, Dennis A.; Mishonov, Alexey V.

doi:10.1016/s0967-0645(02)00589-1

Cited by 112 publications

(86 citation statements)

References 42 publications

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“…5). This is most likely due to an elevation in bottle POC as has been confirmed by a range of studies that directly compare bottles and pumps using small pore sized filters (0.7-1 Am diameter) typically made of glass or quartz fiber Gardner et al, 2003;Liu et al, 2005). At low POC concentrations (few AM POC) this bias has been attributed to dissolved organic carbon (DOC) sorption on to the filter.…”

Section: Methodological Issues-traditional Particle Sampling Methodsmentioning

confidence: 91%

“…This bias would be higher in high DOC surface waters and more evident in small volume bottle samples . One alternative explanation is simply that bottle POC is higher due to the smaller pore size of GFF filters (nominal pore size of 0.7 Am) used with bottle POC methods vs. the quartz filters (nominal pore size of 1 Am) typically used with pumps (Dunne et al, 1997;Gardner et al, 2003). For example, Dunne et al (1997) compared collection of chlorophyll and 234 Th from bottle and pump pairs and concluded that pump POC concentrations had to be increased by a factor of 1.1 to 2.3 for accurate comparison with bottle POC because of the pore size differences and the abundance of small cells in their study.…”

Section: Methodological Issues-traditional Particle Sampling Methodsmentioning

confidence: 99%

“…The challenges of collecting unbiased or truly representative marine particle samples have been known for some time. These challenges apply to studies of the smallest colloids isolated via cross flow filtration (e.g., Buesseler et al, 1996) to those of larger particles where differences in POC concentrations between bottle filtration and in situ pumps have been documented Gardner et al, 2003;Liu et al, 2005). Differences in C / 234 Th as a function of sampling method will be discussed separately below.…”

Section: Overview Of Processes Controlling the C / 234 Th Ratio Of Mamentioning

confidence: 99%

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An assessment of particulate organic carbon to thorium-234 ratios in the ocean and their impact on the application of 234Th as a POC flux proxy

et al. 2006

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Thorium-234 is increasingly used as a tracer of ocean particle flux, primarily as a means to estimate particulate organic carbon export from the surface ocean. This requires determination of both the 234 Th activity distribution (in order to calculate 234 Th fluxes) and an estimate of the C / 234 Th ratio on sinking particles, to empirically derive C fluxes. In reviewing C / 234 Th variability, results obtained using a single sampling method show the most predictable behavior. For example, in most studies that employ in situ pumps to collect size fractionated particles, C / 234 Th either increases or is relatively invariant with increasing particle size (size classes N 1 to 100s Am). Observations also suggest that C / 234 Th decreases with depth and can vary significantly between regions (highest in blooms of large diatoms and highly productive coastal settings). Comparisons of C fluxes derived from 234 Th show good agreement with independent estimates of C flux, including mass balances of C and nutrients over appropriate space and time scales (within factors of 2-3). We recommend sampling for C / 234 Th from a standard depth of 100 m, or at least one depth below www.elsevier.com/locate/marchem the mixed layer using either large volume size fractionated filtration to capture the rarer large particles, or a sediment trap or other device to collect sinking particles. We also recommend collection of multiple 234 Th profiles and C / 234 Th samples during the course of longer observation periods to better sample temporal variations in both 234 Th flux and the characteristic of sinking particles. We are encouraged by new technologies which are optimized to more reliably sample truly settling particles, and expect the utility of this tracer to increase, not just for upper ocean C fluxes but for other elements and processes deeper in the water column. D

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Section: Methodological Issues-traditional Particle Sampling Methodsmentioning

confidence: 91%

Section: Methodological Issues-traditional Particle Sampling Methodsmentioning

confidence: 99%

Section: Overview Of Processes Controlling the C / 234 Th Ratio Of Mamentioning

confidence: 99%

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An assessment of particulate organic carbon to thorium-234 ratios in the ocean and their impact on the application of 234Th as a POC flux proxy

et al. 2006

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“…The introduction of the first commercial transmissometers spawned the investigation of PM and particulate organic carbon concentration (POC) relationships with beam attenuation coefficient (Bishop, 1986(Bishop, , 1999Bishop et al, 1999Bishop et al, , 1992Bishop and Joyce, 1986;Bishop and Wood, 2008;Cetinic et al, 2012;Gardner, 1989a;Gardner et al, 1985Gardner et al, , 2003Gardner et al, , 1993Hill et al, 2011;Karageorgis et al, 2008Karageorgis et al, , 2014Neukermans et al, 2012). The beam attenuation coefficient was found to be a better proxy for POC than for PM for waters dominated by biogenic particles, having a smaller intercept and a significantly higher correlation coefficient (Bishop, 1999;Gardner et al, 2003).…”

Section: Commercial Technology To Measure Optical Properties In-situmentioning

confidence: 99%

“…The beam attenuation coefficient was found to be a better proxy for POC than for PM for waters dominated by biogenic particles, having a smaller intercept and a significantly higher correlation coefficient (Bishop, 1999;Gardner et al, 2003).…”

Section: Commercial Technology To Measure Optical Properties In-situmentioning

confidence: 99%

Optical techniques for remote and in-situ characterization of particles pertinent to GEOTRACES

Boss

Guidi

Richardson

et al. 2015

Progress in Oceanography

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a b s t r a c tField and laboratory characterization of marine particles is laborious and expensive. Proxies of particle properties have been developed that allow researchers to obtain high frequency distributions of such properties in space or time. We focus on optical techniques used to characterize marine particles in-situ, with a focus on GEOTRACES-relevant properties, such as bulk properties including particle mass, crosssectional area, particle size distribution, particle shape information, and also single particle optical properties, such as individual particle type and size. We also address the use of optical properties of particles to infer particulate organic or inorganic carbon. In addition to optical sensors we review advances in imaging technology and its use to study marine particles in situ. This review addresses commercially available technology and techniques that can be used as a proxy for particle properties and the associated uncertainties with particular focus to open ocean environments, the focus of GEOTRACES.

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Distribution and composition of suspended biogenic particles in surface waters across Subarctic and Arctic Seas

et al. 2013

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Suspended biogenic particles were examined across Subarctic and Arctic Seas during the Canada‐Three‐Oceans (C3O) program in the summers of 2007 and 2008. Particulate organic carbon (POC) and nitrogen (PON), biogenic silica (bSiO2), and size‐fractionated chlorophyll a (chl a) concentrations were measured within the euphotic zone throughout five domains: Eastern Subarctic North Pacific (ESNP), Bering and Chukchi Seas (BE‐CH), Southern Beaufort Sea and Canada Basin (BS‐CB), Canadian Arctic Archipelago (CAA), and Baffin Bay and Labrador Sea (BB‐LS). Despite large variability along the sampling transect and vertically throughout the euphotic zone, domain averages of depth‐integrated POC and PON were relatively invariant across the ESNP, BE‐CH, CAA, and BB‐LS, ranging from 546 to 670 mmol m−2 (POC) and 101 to 154 mmol m−2 (PON), but were much lower in BS‐CB (199 and 78 mmol m−2, respectively). In contrast, depth‐integrated bSiO2 averages were highest in BE‐CH and CAA (>100 mmol m−2), intermediate in ESNP and BB‐LS (34–48 mmol m−2), and low in BS‐CB (6 mmol m−2). Similarly to the bSiO2 distribution, the biomass of the >5 μm chl a size‐fraction averaged 68–69% of total chl a in BE‐CH and CAA, 56% in BB‐LS, and 22–23% in ESNP and BS‐CB. Ratios of bSiO2:PON averaged 1.10–1.30 in BE‐CH and CAA, 0.30–0.34 in ESNP and BB‐LS, and 0.08 in BS‐CB. This study highlights the relative importance of siliceous phytoplankton such as diatoms in BE‐CH and CAA, smaller nonsiliceous cells in BS‐CB and ESNP, and a mixed assemblage of variably sized phytoplankton with a less siliceous component in BB‐LS.

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Determining true particulate organic carbon: bottles, pumps and methodologies

Cited by 112 publications

References 42 publications

An assessment of particulate organic carbon to thorium-234 ratios in the ocean and their impact on the application of 234Th as a POC flux proxy

An assessment of particulate organic carbon to thorium-234 ratios in the ocean and their impact on the application of 234Th as a POC flux proxy

Optical techniques for remote and in-situ characterization of particles pertinent to GEOTRACES

Distribution and composition of suspended biogenic particles in surface waters across Subarctic and Arctic Seas

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