Global database of ratios of particulate organic carbon to thorium-234 in the ocean: improving estimates of the biological carbon pump
- 1School of Science, Centre for Marine Ecosystems Research, Edith Cowan University, Joondalup WA 6027, Australia
- 2Institut de Ciència i Tecnologia Ambientals and Departament de Física, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain
- 3Mediterranean Institute of Oceanography, UM110 CNRS, Aix-Marseille Université, IRD, 13288 Marseille, France
- acurrently at: International Atomic Energy Agency, 4a Quai Antoine 1er, 98000 Principality of Monaco, Monaco
Correspondence: Viena Puigcorbé (firstname.lastname@example.org)
The ocean's biological carbon pump (BCP) plays a major role in the global carbon cycle. A fraction of the photosynthetically fixed organic carbon produced in surface waters is exported below the sunlit layer as settling particles (e.g., marine snow). Since the seminal works on the BCP, global estimates of the global strength of the BCP have improved but large uncertainties remain (from 5 to 20 Gt C yr−1 exported below the euphotic zone or mixed-layer depth). The 234Th technique is widely used to measure the downward export of particulate organic carbon (POC). This technique has the advantage of allowing a downward flux to be determined by integrating the deficit of 234Th in the upper water column and coupling it to the POC∕234Th ratio in sinking particles. However, the factors controlling the regional, temporal, and depth variations of POC∕234Th ratios are poorly understood. We present a database of 9318 measurements of the POC∕234Th ratio in the ocean, from the surface down to >5500 m, sampled on three size fractions ( µm, ∼1–50 µm, µm), collected with in situ pumps and bottles, and also from bulk particles collected with sediment traps. The dataset is archived in the data repository PANGAEA® under https://doi.org/10.1594/PANGAEA.911424 (Puigcorbé, 2019). The samples presented in this dataset were collected between 1989 and 2018, and the data have been obtained from published papers and open datasets available online. Unpublished data have also been included. Multiple measurements can be found in most of the open ocean provinces. However, there is an uneven distribution of the data, with some areas highly sampled (e.g., China Sea, Bermuda Atlantic Time Series station) compared to some others that are not well represented, such as the southeastern Atlantic, the south Pacific, and the south Indian oceans. Some coastal areas, although in a much smaller number, are also included in this global compilation. Globally, based on different depth horizons and climate zones, the median POC∕234Th ratios have a wide range, from 0.6 to 18 µmol dpm−1.
The vertical export of photosynthetically produced particulate organic carbon, from the surface waters to the deep ocean (i.e., biological carbon pump; Eppley and Peterson, 1979), has a strong impact in the global carbon cycle. Through this process, the ocean stores carbon dioxide (CO2) away from the atmosphere and buffers the global climate system (Kwon et al., 2009). Indeed, estimates suggest that atmospheric CO2 levels would be 200 ppm higher than current concentrations without the biological carbon pump (Parekh et al., 2006). However, quantifying the magnitude of the biological carbon pump at both the regional and global scales is challenging and current assessments vary widely, with estimates ranging from 5 to 20 Gt C yr−1 being exported below the euphotic zone or the mixed-layer depth (Guidi et al., 2015; Henson et al., 2011; Laws et al., 2011).
Downward export fluxes of organic carbon can be estimated using (i) indirect approaches derived from nutrient uptake (Le Moigne et al., 2013a; Pondaven et al., 2000; Sanders et al., 2005), radioisotopes (Cochran and Masqué, 2003), satellite empirical algorithms (Dunne et al., 2007; Henson et al., 2011; Laws et al., 2011), underwater video systems (Guidi et al., 2008), or (ii) direct measurements using various designs of sediment traps (Buesseler et al., 2007; Engel et al., 2017; Lampitt et al., 2008; Owens et al., 2013) or marine snow catchers (Cavan et al., 2015; Riley et al., 2012).
Here we focus on the use of radioisotopes, specifically, 234Th. The 234Th approach allows us to quantify an export flux from (i) a water profile of 234Th to obtain its deficit relative to 238U combined with (ii) an estimate of the ratio of POC concentration to 234Th activity (POC∕Th ratio) in sinking matter (Buesseler et al., 1992). In reviewing POC∕Th ratio variability using the data available at the time, Buesseler et al. (2006) found that the POC∕Th ratios (i) increase or remain constant with increasing particle size and (ii) decrease with depth. Regionally, the POC∕Th ratios vary largely between oceanic provinces and regimes (Puigcorbé et al., 2017a). The study of the biogeochemical behavior of 234Th with regards to marine particles has received significant attention (Maiti et al., 2010; Le Moigne et al., 2013c; Puigcorbé et al., 2015; Rosengard et al., 2015; Santschi et al., 2006), and the availability of 234Th-related data has been enhanced thanks to international and national programs such as GEOTRACES (Mawji et al., 2015; Schlitzer et al., 2018), JGOFS (Joint Global Ocean Flux Study) (Buesseler et al., 1998, 1995, 2001), or VERTIGO (Buesseler et al., 2008b), yet the factors controlling the variations in the POC∕Th ratio as a function of region, time, particle size and type, and water column depth remain poorly understood. Assessing the influence of such factors on the POC∕Th ratios will contribute to improve our modeling efforts and our capacity to predict the export and fate of the organic carbon produced in the surface layers. Indeed, the necessity to constrain the variability of the POC∕Th was discussed and considered a priority at the technical meeting “The Application of Radionuclides in Studies of the Carbon Cycle and the Impact of Ocean Acidification” held at the International Atomic Energy Agency (IAEA) Environment Laboratories in Monaco in October 2016 (Morris et al., 2017).
Therefore, we compiled a database that comprises 9318 POC∕Th ratios collected between 1989 and 2018 covering most oceanic provinces at depths ranging from 0 to >5500 m. The particles were collected using collection bottles (i.e., Niskin), in situ pumps, or sediment traps, and they include bulk and size fractionated samples. This database significantly increases the pool of POC∕Th ratio data available at the time of Buesseler et al. (2006) and enables us to test the influence of various factors on the variability of POC∕Th ratios. Among other information, the influence of biogeochemical characteristics of the area (e.g., nutrient concentrations) together with the surface productivity levels, phytoplankton compositions, and zooplankton abundance could be examined through satellites products and/or global databases (e.g., Buitenhuis et al., 2013; Moriarty et al., 2013; Moriarty and O'Brien, 2013).
2.1 The 234Th approach
The short-lived radionuclide thorium-234 (234Th, d) is widely used to estimate the magnitude of POC that escapes the upper ocean layers (e.g., the euphotic zone) (Waples et al., 2006). 234Th is the decay product of uranium-238 (238U, yr). While uranium is conservative and proportional to salinity in well-oxygenated seawater (Chen et al., 1986; Ku et al., 1977; Owens et al., 2011), thorium is not soluble in seawater and it is scavenged by particles as they form and/or sink along the water column. As a consequence, a radioactive disequilibrium between 238U and 234Th can be observed, mainly in the upper layers of the water column, which at first approximation, is proportional to the numbers of particles exported and hence can be used to estimate particle and elemental export fluxes.
A one-box scavenging model (see review by Savoye et al., 2006, and references therein) is commonly applied to calculate 234Th export rates. Steady-state (SS) or non-steady-state (NSS) conditions are assumed depending on the conditions at the sampling time and the possibility to reoccupy locations within an adequate timescale. Le Moigne et al. (2013b) reported 234Th fluxes from both types of models in their database with flux integration depths spanning from the surface down to 300 m, although the most common integration depths were between 100 and 150 m. The choice of export depth when using the 234Th technique is not trivial. Rosengard et al. (2015) provide recommendations to the various manners of choosing the export depth in order to integrate the 234Th fluxes. Once the 234Th export flux is estimated, it is multiplied by the ratio of POC to particulate 234Th activity in sinking particles to obtain the POC flux. The sinking particles from which the ratio is measured should, ideally, be collected at the depth where the export has been estimated and represent the pool of particles that are driving the export of organic carbon.
2.2 The crux of the 234Th approach: POC∕Th ratios of sinking particles
The determination of the POC∕Th ratio has been historically attained by assuming that sinking carbon is driven by large particles, generally >50 µm in size (researchers also use 51, 53, or 70 µm, depending on the mesh supplier) whereas organic carbon within small particles is assumed to remain suspended and therefore not contribute to the export flux (Bishop et al., 1977; Fowler and Knauer, 1986). However, recent studies have shown that small particles can be significant players in the particle export and should not be disregarded (Alonso-González et al., 2010; Durkin et al., 2015; Le Gland et al., 2019; Puigcorbé et al., 2015; Richardson, 2019), particularly in oligotrophic regions. The most common methods to obtain the particulate fraction to measure the POC∕Th ratio are (i) in situ pumps (ISPs), which can allow for sampling different particle sizes; (ii) collection bottles (CBs) such as Niskin bottles, providing bulk particles, i.e., >0.7 or 1 µm particles; (iii) sediment traps (STs); and although less common (iv) marine snow catchers. In some instances various methods have been used in combination (Cai et al., 2010; Maiti et al., 2016; Puigcorbé et al., 2015).
Different sampling devices have been shown to provide differences in POC∕Th ratios, usually within a factor of 2 to 4 (Buesseler et al., 2006). The differences can be related to the collection of different particle pools and/or the enhanced presence of swimmers. STs collect sinking particles and may suffer from hydrodynamic discrimination and undersample slow-sinking particles (Gustafsson et al., 2004). CBs sample both sinking and suspended particles similar to ISPs. ISPs filter large volumes of water and have been suggested to potentially undersample some of the fast-sinking particles (Lepore et al., 2009) and sample neutrally buoyant C-rich aggregates (i.e., non-sinking but with high POC∕Th ratios) (Lalande et al., 2008). Biases due to washout of large particles when using ISPs (Bishop et al., 2012) or aggregate collapse induced by their high cross-filter pressure (Gardner et al., 2003) may further enhance these differences. The presence of swimmers can also be an important bias of POC∕Th ratios when not thoroughly removed, since they skew measurements towards higher values because of their high POC proportion compared to 234Th (Buesseler et al., 1994; Coale, 1990).
2.3 POC∕234Th ratio variability
Despite the significant body of literature available on POC∕Th ratios, more than 10 years after the review by Buesseler et al. (2006) we still cannot explain the variability of the POC∕Th ratios with depth, time, particle type and size, or sinking velocity easily or at a global level. Changes with size and depth have been the most extensively examined. The relation between POC∕Th ratio and particle size has been assessed before, with results suggesting that there is not a direct relationship. Previous studies have reported increasing ratios with increasing particle size (Benitez-Nelson et al., 2001; Buesseler et al., 1998; Cochran et al., 2000), which has been interpreted as an effect of the volume-to-surface area ratio of the particles, due to 234Th being surface bound whereas C would be contained within the particles (Buesseler et al., 2006). Yet, a number of studies have reported the opposite trend (i.e., decreasing ratio with increasing particle size; Bacon et al., 1996; Hung et al., 2010; Planchon et al., 2013; Puigcorbé et al., 2015) or no clear change with size (Hung and Gong, 2010; Lepore et al., 2009; Speicher et al., 2006). Depth is another factor that has been considered when assessing the variability of POC∕Th, since particles are produced in the surface layer and are remineralized on their transit along the water column (Martin et al., 1987). POC∕Th ratios have been found to be attenuated with depth (Jacquet et al., 2011; Planchon et al., 2015; Puigcorbé et al., 2015). This is due to (in no order or importance) decreasing autotrophic production with increasing water depth, preferential C loss compared to 234Th through remineralization processes, changes in superficial binding ligands along the water column, and/or scavenging of 234Th during particle sinking resulting in enhanced particulate 234Th activities (Buesseler et al., 2006; Rutgers van der Loeff et al., 2002), leading to significant variability in the attenuation rates. Theoretically, high sinking velocities may limit the variations in POC∕Th ratios with depth, owing to shorter residence times limiting the impacts of biotic and abiotic processes. However, using specifically designed STs that segregate particles according to their in situ sinking velocities, Szlosek et al. (2009) observed no consistent trend between POC∕Th ratios and sinking velocities.
The truth is that numerous processes can impact the POC∕Th ratios apart from particle size or depth, such as particle composition or aggregation–disaggregation processes mediated by physical or biological activity (Buesseler and Boyd, 2009; Burd et al., 2010; Maiti et al., 2010; Szlosek et al., 2009), which adds a level of complexity to the prediction of their variability in the ocean. Yet, due to the significance of the POC∕Th ratios for the accuracy of the 234Th flux method, the effort should be made to constrain the factors that will impact its variability, and a number of environmental and biogeochemical parameters can be assessed with that goal at a global scale. Among others, surface productivity, phytoplankton composition, zooplankton abundance, mixed-layer depth, dust inputs to the surface ocean, and ice cover (Buitenhuis et al., 2013; Mahowald et al., 2009; Moriarty et al., 2013; Moriarty and O'Brien, 2013) are all potential candidates to test their global patterns against POC∕Th ratio variability.
3.1 Data classification
Our dataset is archived in the data repository PANGAEA® (http://www.pangaea.de), https://doi.org/10.1594/PANGAEA.911424 (Puigcorbé, 2019). Latitude, longitude, and sampling dates are reported. When dates of the individual stations were not reported in the original publications, we allocated the midpoint of the sampling period as the sampling date. The same was done when the specific sampling coordinates were not available (see details in the comments related to the dataset; https://doi.org/10.1594/PANGAEA.902103; Puigcorbé, 2019). The database consists of 9318 measurements of POC∕Th ratios in the ocean. Particles were collected using in situ pumps (ISPs), water collection bottles (CBs), and sediment traps (STs). We refer to “bulk” (BU) for particles sampled using CBs and ISPs with a pore size filter of 0.2–1 µm. For this group of samples, particles >0.7 µm were collected using GFF filters and >1 µm using QMA filters. In some particular cases other types of filters, with a different pore size (e.g., 0.2, 0.45, or 0.6 µm) might have been used (see database for details). Hereafter, we use >1 µm for the bulk particles. We refer to “small particles” (SPs) for particles usually collected using ISPs on a 1–50 µm mesh size and “large particles” (LPs) for particles usually collected using ISPs on mesh size >50 µm (see details on other size ranges also used in the database). Finally, some POC∕Th ratios were measured in sinking particles sampled using sediment traps (STs). Figure 1 shows the global distribution of POC∕Th ratios grouped by these four categories: BU, LP, SP, and ST. The POC∕Th ratios were obtained from particles collected at various depths from the surface to >5500 m (Fig. 2). All the information on locations, dates, depth, size fractions/device (BU, SP, LP, and ST), and references is included as metadata in the online database and presented in Table 1.
Our database covers POC∕Th measurements sampled between 1989 and 2018, including unpublished data from our laboratories or graciously made available to us by colleagues and data available in online databases. Figure 3 shows the number of POC∕Th measurements available per year. In the years 1997, 2004, 2005, 2008, 2010, 2011, and 2013, the number of POC∕Th measurements was >500. This highlights dedicated carbon export programs such as the Joint Global Ocean Flux Study (JGOFS) (Buesseler et al., 1998, 1992, 1995, 2001; Murray et al., 1996, 2005), the VERTIGO (Vertical Transport in the Global Ocean) voyages in the Pacific Ocean (Buesseler et al., 2008b), and the GEOTRACES program (Mawji et al., 2015; Schlitzer et al., 2018), as well as the maintained effort of the time series stations (Kawakami et al., 2004, 2010, 2015; Kawakami and Honda, 2007). Sampling effort also varied depending on the month of the year (Fig. 3b), with late spring–summer months being the most highly sampled in both hemispheres. The Northern Hemisphere has been largely sampled in September, May, and June (49, 10, and 5 times more data than in the Southern Hemisphere, respectively), whereas the Southern Hemisphere has been more sampled in December and February (5 and 4 times more data than in the Northern Hemisphere, respectively), with no data available for the months of July and August and only five data points in September (austral winter). For the rest of the months, the Northern Hemisphere presents 1.4–1.8 times more data than the Southern Hemisphere. In the equatorial region (taken as the latitudes between −10 and 10∘ N) major sampling efforts took place in May, with no data collected in January and just eight data points available from December. The monthly distribution is, therefore, globally biased towards the warmer and more productive seasons, leaving the winter months largely undersampled, particularly in the Southern Hemisphere.
3.2 Global variability: climate zones and depth horizons
The global variability of POC∕Th ratios looking at six different depths horizons (50, 100, 200, 500, 1000, and > 1000 m) and grouped by climatic zones (polar >66.5∘, subpolar 66.5–50∘, temperate 50–35∘, subtropical 35–23.5∘, and tropical 23.5∘ N–23.5∘ S) is presented in Fig. 4. A PERMANOVA analysis was conducted to examine the data, and the results indicate that all the depth horizons defined here were significantly different (p<0.05). Significant differences were also found between climatic zones, except between the temperate and subtropical zones and between the subtropical and the tropical zones, when considering all the data together. Statistical differences between zones within a certain depth range are shown in Fig. 4.
In general, we observe a reduction in POC∕Th ratios with depth, previously reported by others (Buesseler et al., 2006), and likely mainly due to the remineralization of carbon along the water column. The decrease is particularly marked in the upper 200 m, where biological processes affecting the ratios are more intense, and then it smoothes below that depth horizon as the strength of these processes is more limited below the euphotic zone. It is worth noticing that some studies, particularly in coastal areas, presented extremely large POC∕Th ratios (>100 µmol dpm−1, not included in Fig. 4). These high ratios are not always discussed in the publications, but the presence of live zooplankton (Buesseler et al., 2009; Savoye et al., 2008; Trull et al., 2008), especially in BU, ST, and LP fractions, when not picked out can be the cause for those high values and should be considered with caution.
Regarding the climate zones, there is significant variability, but, in general, large POC∕Th ratios occur more often in productive and high-latitude regions relative to low-latitude tropical areas, particularly in the upper 200 m (Fig. 4). When looking at the different types of sampling methods, the link between latitude and magnitude of the ratio seems to be clear for ST and BU but quite variable for LP and SP (Fig. 5). High POC∕Th ratios are usually associated with the presence of large phytoplankton groups, such as diatoms, which are dominant in high-latitude areas with no nutrient limitations, or where zooplankton populations are large and there is a significant input of fecal pellets, which should also have high POC∕Th ratios. Low ratios, on the other hand, are commonly observed in warm oligotrophic areas where productivity is limited and the main phytoplanktonic groups are picoplankton (Buesseler et al., 2006). Exceptions do exist, but they are usually found in coastal areas where other factors could be influencing the planktonic community (e.g., seasonal upwelling, continental influence, river inputs).
3.3 Contributing to global POC export estimates
The 234Th approach has been used to derive an export model at the global scale that uses sea surface temperatures and net primary productivity from satellite products (Henson et al., 2011). The parametrization for this model has large uncertainties in the cold regions (low sea surface temperature), which lead to a reduced estimate of the global biological carbon pump (∼5 Gt C yr−1) compared to other satellite-derived export models (9–13 Gt C yr−1; Dunne et al., 2007; Laws et al., 2011). A recent study by Puigcorbé et al. (2017a) estimated POC export fluxes in the North Atlantic using in situ data for the 234Th method and compared it to three different satellite-derived export models: Dunne et al. (2007), Henson et al. (2011), and Laws et al. (2011). The conclusion was that, overall, the geographical trends were captured by all the approaches, but the absolute values between them could reach important discrepancies. In that study, the authors advised a revision of the parametrization of the models going beyond sea surface temperatures in order to adjust to specific ocean bioregions. This database sets a strong background to develop that parametrization and contribute to similar modeling efforts to constrain the global carbon export fluxes as done by Henson et al. (2011).
3.4 Significant gaps and recommendations
This database provides the global POC∕Th ratios sampled from all the oceans up until 2018. The sampling coverage is significant but it is not evenly distributed. Areas such as the China Sea, Arabian Sea, northwestern Mediterranean Sea, central Pacific, and high latitudes of the Atlantic Ocean are well represented, whereas other areas, such as the oligotrophic gyres, west Pacific, or the Southern Ocean, present important gaps. The data are not evenly distributed between seasons either, with most of the sampling taking place during spring and summer in both hemispheres, which is also when the export fluxes are expected to be larger. High seasonality in undersampled areas could potentially bias our global view of the POC∕Th ratios and have an impact on the Th-derived carbon export flux estimates.
It would be beneficial for future efforts to obtain data for those undersampled areas with high seasonality to better characterize the expected variability in the ratios within those areas and to cover a larger span of seasons in order to better understand the seasonality of POC∕Th and thus be able to translate it more accurately to the global POC export estimates.
Here we provide a global database of 9318 estimates of POC∕Th ratios collected between 1989 and 2018 at various depths from below the surface to >5500 m using in situ pumps, collection bottles, and sediment traps. The observed pattern of POC∕Th ratios reflects a decrease with depth and a link with the latitude, with higher ratios usually observed in high-latitude areas. Some noteworthy gaps in the dataset are the Benguela system, the Mauritanian upwelling, the western and south Pacific, and the southern Indian Ocean. The fall–winter months in both hemispheres are also underrepresented. The temporal and spatial undersampling of some areas could bias the global view of the POC∕Th ratios. Despite the gaps, this database is the largest compilation POC∕Th ratios to date and could be used to better understand the factors controlling the variation in ratios on a global scale. This will help revise and provide improved estimates of the ocean's biological carbon pump.
VP and FACLM compiled the dataset and prepared and reviewed the manuscript. All the authors contributed to the review of the manuscript.
The authors declare that they have no conflict of interest.
We are very grateful to all of those who have provided data for this global database, especially to those authors who have provided unpublished data to make this database as complete as possible. We would also like to thank Elena Ceballos and Sian McNamara who helped during the preparation of the database. We also thank Daniela Ransby, from the PANGAEA Data Archiving & Publication team, for her support and efficiency during the data submission process. Viena Puigcorbé received funding from the School of Science at Edith Cowan University to compile the dataset and facilitate the collaboration with Frédéric A. C. Le Moigne (G1003879). This work is contributing to the ICTA “Unit of Excellence” (MinECo, MDM2015-0552). Thanks also to the Radioecology Laboratory of the IAEA for hosting the technical meeting “The Application of Radionuclides in Studies of the Carbon Cycle and the Impact of Ocean Acidification”, and in particular to Stephanie Morris and all the participants for the fruitful discussions.
This research has been supported by the Edith Cowan University (grant no. G1003879).
This paper was edited by David Carlson and reviewed by Erin Black and one anonymous referee.
Alkalay, R., Zlatkin, O., Katz, T., Herut, B., Halicz, L., Berman-Frank, I., and Weinstein, Y.: Carbon export and drivers in the southeastern Levantine Basin, Deep-Sea Res. Pt. II, 171, 104713, doi10.1016/j.dsr2.2019.104713, 2020.
Alonso-González, I. J., Arístegui, J., Lee, C., Sanchez-Vidal, A., Calafat, A., Fabrés, J., Sangrá, P., Masqué, P., Hernández-Guerra, A., and Benítez-Barrios, V.: Role of slowly settling particles in the ocean carbon cycle, Geophys. Res. Lett., 37, L13608, https://doi.org/10.1029/2010GL043827, 2010.
Amiel, D. and Cochran, J. K.: Terrestrial and marine POC fluxes derived from 234Th distributions and δ13C measurements on the Mackenzie Shelf, J. Geophys. Res.-Oceans, 113, C03S06, https://doi.org/10.1029/2007JC004260, 2008.
Amiel, D., Cochran, J. K., and Hirschberg, D. J.: 234Th∕238U disequilibrium as an indicator of the seasonal export flux of particulate organic carbon in the North Water, Deep-Sea Res. Pt. II, 49, 5191–5209, 2002.
Anand, S. S., Rengarajan, R., Sarma, V. V. S. S., Sudheer, A. K., Bhushan, R., and Singh, S. K.: Spatial variability of upper ocean POC export in the Bay of Bengal and the Indian Ocean determined using particle-reactive 234Th, J. Geophys. Res.-Oceans, 122, 3753–3770, https://doi.org/10.1002/2016JC012639, 2017.
Anand, S. S., Rengarajan, R., and Sarma, V. V. S. S.: 234Th-Based Carbon Export Flux Along the Indian GEOTRACES GI02 Section in the Arabian Sea and the Indian Ocean, Global Biogeochem. Cycles, 32, 1–20, https://doi.org/10.1002/2017GB005847, 2018a.
Anand, S. S., Rengarajan, R., Shenoy, D., Gauns, M., and Naqvi, S. W. A.: POC export fluxes in the Arabian Sea and the Bay of Bengal: A simultaneous 234Th∕238U and 210Po∕210Pb study, Mar. Chem., 198, 70–87, https://doi.org/10.1016/j.marchem.2017.11.005, 2018b.
Aono, T., Yamada, M., Kudo, I., Imai, K., Nojiri, Y., and Tsuda, A.: Export fluxes of particulate organic carbon estimated from 234Th∕238U disequilibrium during the Subarctic Pacific Iron Experiment for Ecosystem Dynamics Study (SEEDS 2001), Prog. Oceanogr., 64, 263–282, https://doi.org/10.1016/j.pocean.2005.02.013, 2005.
Bacon, M. P., Cochran, J. K., Hirschberg, D., Hammar, T. R., and Fleer, A. P.: Export flux of carbon at the equator during the EqPac time-series cruises estimated from 234Th measurements, Deep-Sea Res. Pt. II, 43, 1133–1153, https://doi.org/10.1016/0967-0645(96)00016-1, 1996.
Baskaran, M., Swarzenski, P. W., and Porcelli, D.: Role of colloidal material in the removal of 234Th in the Canada basin of the Arctic Ocean, Deep-Sea Res. Pt. I, 50, 1353–1373, https://doi.org/10.1016/S0967-0637(03)00140-7, 2003.
Baumann, M. S., Moran, S. B., Lomas, M. W., Kelly, R. P., and Bell, D. W.: Seasonal decoupling of particulate organic carbon export and net primary production in relation to sea-ice at the shelf break of the eastern Bering Sea: Implications for off-shelf carbon export, J. Geophys. Res.-Oceans, 118, 1–19, https://doi.org/10.1002/jgrc.20366, 2013.
Benitez-Nelson, C., Buesseler, K. O., Karl, D. M., and Andrews, J.: A time-series study of particulate matter export in the North Pacific Subtropical Gyre based on 234Th: 238U disequilibrium, Deep-Sea Res. Pt. I, 48, 2595–2611, https://doi.org/10.1016/S0967-0637(01)00032-2, 2001.
Benitez-Nelson, C. R., Buesseler, K. O., and Crossin, G.: Upper ocean carbon export, horizontal transport, and vertical eddy diffusivity in the southwestern Gulf of Maine, Cont. Shelf Res., 20, 707–736, https://doi.org/10.1016/S0278-4343(99)00093-X, 2000.
Bishop, J. K. B., Edmond, J. M., Ketten, D. R., Bacon, M. P., and Silker, W. B.: The chemistry, biology, and vertical flux of particulate matter from the upper 400 m of the equatorial Atlantic Ocean, Deep-Sea Res., 24, 511–548, https://doi.org/10.1016/0146-6291(77)90526-4, 1977.
Bishop, J. K. B., Lam, P. J., and Wood, T. J.: Getting good particles: Accurate sampling of particles by large volume in-situ filtration, Limnol. Oceanogr. Methods, 10, 681–710, https://doi.org/10.4319/lom.2012.10.681, 2012.
Black, E. E., Buesseler, K. O., Pike, S. M., and Lam, P. J.: 234Th as a tracer of particulate export and remineralization in the southeastern tropical Pacific, Mar. Chem., 201, 35–50, https://doi.org/10.1016/J.MARCHEM.2017.06.009, 2018.
Brew, H. S., Moran, S. B., Lomas, M. W., and Burd, A. B.: Plankton community composition, organic carbon and thorium-234 particle size distributions, and particle export in the Sargasso Sea, J. Mar. Res., 67, 845–868, https://doi.org/10.1357/002224009792006124, 2009.
Buesseler, K., Ball, L., Andrews, J., Benitez-Nelson, C., Belastock, R., Chai, F., and Chao, Y.: Upper ocean export of particulate organic carbon in the Arabian Sea derived from thorium-234, Deep-Sea Res. Pt. II, 45, 2461–2487, https://doi.org/10.1016/S0967-0645(98)80022-2, 1998.
Buesseler, K. O. and Boyd, P. W.: Shedding light on processes that control particle export and flux attenuation in the twilight zone of the open ocean, Limnol. Oceanogr., 54, 1210–1232, https://doi.org/10.4319/lo.2009.54.4.1210, 2009.
Buesseler, K. O., Bacon, M. P., Cochran, J. K., and Livingston, H. D.: Carbon and nitrogen export during the JGOFS North Atlantic Bloom Experiment estimated from 234Th: 238U disequilibria, Deep-Sea Res., 39, 1115–1137, https://doi.org/10.1016/0198-0149(92)90060-7, 1992.
Buesseler, K. O., Michaels, A. F., Siegel, D. A., and Knap, A. H.: A three dimensional time-dependent approach to calibrating sediment trap fluxes, Global Biogeochem. Cycles, 8, 179–193, https://doi.org/10.1029/94GB00207, 1994.
Buesseler, K. O., Andrews, J. A., Hartman, M. C., Belastock, R., and Chai, F.: Regional estimates of the export flux of particulate organic carbon derived from thorium-234 during the JGOFS EqPac program, Deep-Sea Res. Pt. II, 42, 777–791, https://doi.org/10.1016/0967-0645(95)00043-P, 1995.
Buesseler, K. O., Steinberg, D. K., Michaels, A. F., Johnson, R. J., Andrews, J. E., Valdes, J. R., and Price, J. F.: A comparison of the quantity and composition of material caught in a neutrally buoyant versus surface-tethered sediment trap, Deep-Sea Res. Pt. I, 47, 277–294, https://doi.org/10.1016/S0967-0637(99)00056-4, 2000.
Buesseler, K. O., Ball, L., Andrews, J., Cochran, J. K., Hirschberg, D. J., Bacon, M. P., Fleer, A., and Brzezinski, M.: Upper ocean export of particulate organic carbon and biogenic silica in the Southern Ocean along 170 W, Deep-Sea Res. Pt. II, 48, 4275–4297, https://doi.org/10.1016/S0967-0645(01)00089-3, 2001.
Buesseler, K. O., Andrews, J. E., Pike, S. M., Charette, M. A., Goldson, L. E., Brzezinski, M. A., and Lance, V. P.: Particle export during the Southern Ocean Iron Experiment (SOFeX), Limnol. Oceanogr., 50, 311–327, 2005.
Buesseler, K. O., Benitez-Nelson, C. R., Moran, S. B., Burd, A., Charette, M., Cochran, J. K., Coppola, L., Fisher, N. S., Fowler, S. W., and Gardner, W. D.: 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, Mar. Chem., 100, 213–233, https://doi.org/10.1016/j.marchem.2005.10.013, 2006.
Buesseler, K. O., Antia, A. N., Chen, M., Fowler, S. W., Gardner, W. D., Gustafsson, O., Harada, K., Michaels, A. F., Rutgers van der Loeff, M., and Sarin, M.: An assessment of the use of sediment traps for estimating upper ocean particle fuxes, J. Mar. Res., 65, 345–416, 2007.
Buesseler, K. O., Lamborg, C., Cai, P., Escoube, R., Johnson, R., Pike, S., Masque, P., McGillicuddy, D., and Verdeny, E.: Particle fluxes associated with mesoscale eddies in the Sargasso Sea, Deep-Sea Res. Pt. II, 55, 1426–1444, https://doi.org/10.1016/j.dsr2.2008.02.007, 2008a.
Buesseler, K. O., Trull, T. W., Steinberg, D. K., Silver, M. W., Siegel, D. A., Saitoh, S.-I., Lamborg, C. H., Lam, P. J., Karl, D. M., Jiao, N. Z., Honda, M. C., Elskens, M., Dehairs, F., Brown, S. L., Boyd, P. W., Bishop, J. K. B., and Bidigare, R. R.: VERTIGO (VERtical Transport In the Global Ocean): A study of particle sources and flux attenuation in the North Pacific, Deep-Sea Res. Pt. II, 55, 1522–1539, https://doi.org/10.1016/j.dsr2.2008.04.024, 2008b.
Buesseler, K. O., Pike, S., Maiti, K., Lamborg, C. H., Siegel, D. A., and Trull, T. W.: Thorium-234 as a tracer of spatial, temporal and vertical variability in particle flux in the North Pacific, Deep-Sea Res. Pt. I, 56, 1143–1167, https://doi.org/10.1016/j.dsr.2009.04.001, 2009.
Buesseler, K. O., McDonnell, A. M. P., Schofield, O. M. E., Steinberg, D. K., and Ducklow, H. W.: High particle export over the continental shelf of the west Antarctic Peninsula, Geophys. Res. Lett., 37, L22606, https://doi.org/10.1029/2010GL045448, 2010.
Buitenhuis, E. T., Vogt, M., Moriarty, R., Bednaršek, N., Doney, S. C., Leblanc, K., Le Quéré, C., Luo, Y.-W., O'Brien, C., O'Brien, T., Peloquin, J., Schiebel, R., and Swan, C.: MAREDAT: towards a world atlas of MARine Ecosystem DATa, Earth Syst. Sci. Data, 5, 227–239, https://doi.org/10.5194/essd-5-227-2013, 2013.
Burd, A. B., Hansell, D. A., Steinberg, D. K., Anderson, T. R., Arístegui, J., Baltar, F., Beaupré, S. R., Buesseler, K. O., DeHairs, F., Jackson, G. A., Kadko, D. C., Koppelmann, R., Lampitt, R. S., Nagata, T., Reinthaler, T., Robinson, C., Robison, B. H., Tamburini, C., and Tanaka, T.: Assessing the apparent imbalance between geochemical and biochemical indicators of meso- and bathypelagic biological activity: What the @$#! is wrong with present calculations of carbon budgets?, Deep-Sea Res. Pt. II, 57, 1557–1571, https://doi.org/10.1016/j.dsr2.2010.02.022, 2010.
Cai, P., Huang, Y., Chen, M., Liu, G., and Qiu, Y.: Export of particulate organic carbon estimated from 234Th-238U disequilibria and its temporal variation in the South China Sea, Chinese Sci. Bull., 46, 1722–1726, https://doi.org/10.1007/BF02900660, 2001.
Cai, P., Dai, M., Chen, W., Tang, T., and Zhou, K.: On the importance of the decay of 234Th in determining size-fractionated C/234Th ratio on marine particles, Geophys. Res. Lett., 33, L23602, https://doi.org/10.1029/2006GL027792, 2006.
Cai, P., Chen, W., Dai, M., Wan, Z., Wang, D., Li, Q., Tang, T., and Lv, D.: A high-resolution study of particle export in the southern South China Sea based on 234Th:238U disequilibrium, J. Geophys. Res.-Oceans, 113, C04019, https://doi.org/10.1029/2007JC004268, 2008.
Cai, P., Rutgers van der Loeff, M., Stimac, I., Nöthig, E. M., Lepore, K., and Moran, S. B.: Low export flux of particulate organic carbon in the central Arctic Ocean as revealed by 234Th: 238U disequilibrium, J. Geophys. Res., 115, C10037, https://doi.org/10.1029/2009JC005595, 2010.
Cai, P., Zhao, D., Wang, L., Huang, B., and Dai, M.: Role of particle stock and phytoplankton community structure in regulating particulate organic carbon export in a large marginal sea, J. Geophys. Res.-Oceans, 120, 2063–2095, https://doi.org/10.1002/2014JC010432, 2015.
Cavan, E. L., Le Moigne, F. A. C., Poulton, A. J., Tarling, G. A., Ward, P., Daniels, C. J., Fragoso, G., and Sanders, R. J.: Attenuation of particulate organic carbon flux in the Scotia Sea, Southern Ocean, is controlled by zooplankton fecal pellets, Geophys. Res. Lett., 42, 821–830, https://doi.org/10.1002/2014GL062744, 2015.
Ceballos-Romero, E., Le Moigne, F. A. C., Henson, S., Marsay, C. M., Sanders, R. J., García-Tenorio, R., and Villa-Alfageme, M.: Influence of bloom dynamics on Particle Export Efficiency in the North Atlantic: a comparative study of radioanalytical techniques and sediment traps, Mar. Chem., 186, 198–210, https://doi.org/10.1016/j.marchem.2016.10.001, 2016.
Charette, M. A. and Moran, S. B.: Rates of particle scavenging and particulate organic carbon export estimated using 234Th as a tracer in the subtropical and equatorial Atlantic Ocean, Deep-Sea Res. Pt. II, 46, 885–906, https://doi.org/10.1016/S0967-0645(99)00006-5, 1999.
Charette, M. A., Moran, S. B., and Bishop, J. K. B.: 234Th as a tracer of particulate organic carbon export in the subarctic northeast Pacific Ocean, Deep-Sea Res. Pt II, 46, 2833–2861, https://doi.org/10.1016/S0967-0645(99)00085-5, 1999.
Charette, M. A., Moran, S. B., Pike, S. M., and Smith, J. N.: Investigating the carbon cycle in the Gulf of Maine using the natural tracer thorium 234, J. Geophys. Res.-Oceans, 106, 11553–11579, https://doi.org/10.1029/1999JC000277, 2001.
Chen, J. H., Lawrence Edwards, R., and Wasserburg, G. J.: 238U, 234U and 232Th in seawater, Earth Planet. Sc. Lett., 80, 241–251, https://doi.org/10.1016/0012-821X(86)90108-1, 1986.
Chen, M., Huang, Y., Cai, P., and Guo, L.: Particulate organic carbon export fluxes in the Canada Basin and Bering Sea as derived from 234Th∕238U disequilibria, Arctic, 56, 32–44, 2003.
Chen, W., Cai, P., Dai, M., and Wei, J.: 234Th∕238U disequilibrium and particulate organic carbon export in the northern South China Sea, J. Oceanogr., 64, 417–428, https://doi.org/10.1007/s10872-008-0035-z, 2008.
Coale, K. H.: Labyrinth of doom: A device to minimize the “swimmer” component in sediment trap collections, Limnol. Oceanogr., 35, 1376–1381, https://doi.org/10.4319/lo.19188.8.131.526, 1990.
Cochran, J. K. and Masqué, P.: Short-lived U∕Th series radionuclides in the ocean: tracers for scavenging rates, export fluxes and particle dynamics, Rev. Mineral. Geochemistry, 52, 461–492, https://doi.org/10.2113/0520461, 2003.
Cochran, J. K., Barnes, C., Achman, D., and Hirschberg, D. J.: Thorium-234/uranium-238 disequilibrium as an indicator of scavenging rates and participate organic carbon fluxes in the Northeast Water Polynya, Greenland, J. Geophys. Res.-Oceans, 100, 4399–4410, https://doi.org/10.1029/94JC01954, 1995.
Cochran, J. K., Buesseler, K. O., Bacon, M. P., Wang, H. W., Hirschberg, D. J., Ball, L., Andrews, J., Crossin, G., and Fleer, A.: Short-lived thorium isotopes (234Th, 228Th) as indicators of POC export and particle cycling in the Ross Sea, Southern Ocean, Deep-Sea Res. Pt. II, 47, 3451–3490, https://doi.org/10.1016/S0967-0645(00)00075-8, 2000.
Coppola, L., Roy-Barman, M., Wassmann, P., Mulsow, S., and Jeandel, C.: Calibration of sediment traps and particulate organic carbon export using 234Th in the Barents Sea, Mar. Chem., 80, 11–26, https://doi.org/10.1016/S0304-4203(02)00071-3, 2002.
Coppola, L., Roy-Barman, M., Mulsow, S., Povinec, P., and Jeandel, C.: Low particulate organic carbon export in the frontal zone of the Southern Ocean (Indian sector) revealed by 234Th, Deep-Sea Res. Pt. I, 52, 51–68, https://doi.org/10.1016/j.dsr.2004.07.020, 2005.
Dai, M. H. and Benitez-Nelson, C. R.: Colloidal organic carbon and 234Th in the Gulf of Maine, Mar. Chem., 74, 181–196, https://doi.org/10.1016/S0304-4203(01)00012-3, 2001.
Dunne, J. P., Sarmiento, J. L., and Gnanadesikan, A.: A synthesis of global particle export from the surface ocean and cycling through the ocean interior and on the seafloor, Glob. Biogeochem. Cycles, 21, GB4006, https://doi.org/10.1029/2006GB002907, 2007.
Durkin, C. A., Estapa, M. L., and Buesseler, K. O.: Observations of carbon export by small sinking particles in the upper mesopelagic, Mar. Chem., 175, 72–81, https://doi.org/10.1016/j.marchem.2015.02.011, 2015.
Engel, A., Wagner, H., Le Moigne, F. A. C., and Wilson, S. T.: Particle export fluxes to the oxygen minimum zone of the eastern tropical North Atlantic, Biogeosciences, 14, 1825–1838, https://doi.org/10.5194/bg-14-1825-2017, 2017.
Eppley, R. W. and Peterson, B. J.: Particulate organic matter flux and planktonic new production in the deep ocean, Nature, 282, 677–680, https://doi.org/10.1038/282677a0, 1979.
Evangeliou, N., Florou, H., and Psomiadou, C.: Size-fractionated particulate organic carbon (POC) export fluxes estimated using 234Th-238U disequilibria in the Saronikos Gulf (Greece) during winter bloom, Fresenius Environ. Bull., 22, 1951–1961, 2013.
Foster, J. M. and Shimmield, G. B.: 234Th as a tracer of particle flux and POC export in the northern North Sea during a coccolithophore bloom, Deep-Sea Res. Pt. II, 49, 2965–2977, https://doi.org/10.1016/S0967-0645(02)00066-8, 2002.
Fowler, S. W. and Knauer, G. A.: Role of large particles in the transport of elements and organic compounds through the oceanic water column, Prog. Oceanogr., 16, 147–194, https://doi.org/10.1016/0079-6611(86)90032-7, 1986.
Friedrich, J. and Rutgers van der Loeff, M.: A two-tracer (210Po-234Th) approach to distinguish organic carbon and biogenic silica export flux in the Antarctic Circumpolar Current, Deep-Sea Res. Pt. I, 49, 101–120, https://doi.org/10.1016/S0967-0637(01)00045-0, 2002.
Gardner, W. D., Richardson, M. J., Carlson, C. A., Hansell, D., and Mishonov, A. V: Determining true particulate organic carbon: bottles, pumps and methodologies, Deep-Sea Res. Pt. II, 50, 655–674, https://doi.org/10.1016/S0967-0645(02)00589-1, 2003.
Guidi, L., Jackson, G. A., Stemmann, L., Miquel, J. C., Picheral, M., and Gorsky, G.: Relationship between particle size distribution and flux in the mesopelagic zone, Deep-Sea Res. Pt. I, 55, 1364–1374, https://doi.org/10.1016/j.dsr.2008.05.014, 2008.
Guidi, L., Legendre, L., Reygondeau, G., Uitz, J., Stemmann, L., and Henson, S. A.: A new look at ocean carbon remineralization for estimating deepwater sequestration, Global Biogeochem. Cycles, 29, 1044–1059, https://doi.org/10.1002/2014GB005063, 2015.
Giuliani, S., Radakovitch, O., Frignani, M., and Bellucci, L. G.: Short time scale variations of 234Th∕238U disequilibrium related to mesoscale variability on the continental slope of the Gulf of Lions (France), Mar. Chem., 106, 403–418, https://doi.org/10.1016/j.marchem.2007.03.007, 2007.
Guo, L., Hung, C. C., Santschi, P. H., and Walsh, I. D.: 234Th scavenging and its relationship to acid polysaccharide abundance in the Gulf of Mexico, Mar. Chem., 78, 103–119, https://doi.org/10.1016/S0304-4203(02)00012-9, 2002.
Gustafsson, Ö. and Andersson, P. S.: 234Th-derived surface export fluxes of POC from the Northern Barents Sea and the Eurasian sector of the Central Arctic Ocean, Deep-Sea Res. Pt. I, 68, 1–11, https://doi.org/10.1016/j.dsr.2012.05.014, 2012.
Gustafsson, Ö., Gschwend, P. M., and Buesseler, K. O.: Using 234Th disequilibria to estimate the vertical removal rates of polycyclic aromatic hydrocarbons from the surface ocean, Mar. Chem., 57, 11–23, https://doi.org/10.1016/S0304-4203(97)00011-X, 1997.
Gustafsson, Ö., Andersson, P., Roos, P., Kukulska, Z., Broman, D., Larsson, U., Hajdu, S., and Ingri, J.: Evaluation of the collection efficiency of upper ocean sub-photic-layer sediment traps: a 24-month in situ calibration in the open Baltic Sea using 234Th, Limnol. Oceanogr. Methods, 2, 62–74, https://doi.org/10.4319/lom.2004.2.62, 2004.
Gustafsson, Ö., Larsson, J., Andersson, P., and Ingri, J.: The POC∕234Th ratio of settling particles isolated using split flow-thin cell fractionation (SPLITT), Mar. Chem., 100, 314–322, https://doi.org/10.1016/j.marchem.2005.10.018, 2006.
Hall, I. R., Schmidt, S., McCave, I. N., and Reyss, J. L.: Particulate matter distribution and disequilibrium along the Northern Iberian Margin: implications for particulate organic carbon export, Deep-Sea Res. Pt. I, 47, 557–582, https://doi.org/10.1016/S0967-0637(99)00065-5, 2000.
Haskell II, W. Z., Berelson, W. M., Hammond, D. E., and Capone, D. G.: Particle sinking dynamics and POC fluxes in the Eastern Tropical South Pacific based on 234Th budgets and sediment trap deployments, Deep-Sea Res. Pt. I, 18, 1–13, https://doi.org/10.1016/j.dsr.2013.07.001, 2013.
Henson, S. A., Sanders, R., Madsen, E., Morris, P. J., Le Moigne, F., and Quartly, G. D.: A reduced estimate of the strength of the ocean's biological carbon pump, Geophys. Res. Lett., 38, L04606, https://doi.org/10.1029/2011GL046735, 2011.
Hung, C.-C. and Gong, G.-C.: Export flux of POC in the main stream of the Kuroshio, Geophys. Res. Lett., 34, L18606, https://doi.org/10.1029/2007GL030236, 2007.
Hung, C. C. and Gong, G. C.: POC∕234Th ratios in particles collected in sediment traps in the northern South China Sea, Estuar. Coast. Shelf Sci., 88, 303–310, https://doi.org/10.1016/j.ecss.2010.04.008, 2010.
Hung, C. C., Guo, L., Roberts, K. A., and Santschi, P. H.: Upper ocean carbon flux determined by the 234Th approach and sediment traps using size-fractionated POC and 234Th data from the Gulf of Mexico, Geochem. J., 38, 601–611, https://doi.org/10.2343/geochemj.38.601, 2004.
Hung, C. C., Xu, C., Santschi, P. H., Zhang, S. J., Schwehr, K. A., Quigg, A., Guo, L., Gong, G. C., Pinckney, J. L., and Long, R. A.: Comparative evaluation of sediment trap and 234Th-derived POC fluxes from the upper oligotrophic waters of the Gulf of Mexico and the subtropical northwestern Pacific Ocean, Mar. Chem., 121, 132–144, https://doi.org/10.1016/j.marchem.2010.03.011, 2010.
Hung, C. C., Gong, G. C., and Santschi, P. H.: 234Th in different size classes of sediment trap collected particles from the Northwestern Pacific Ocean, Geochim. Cosmochim. Ac, 91, 60–74, https://doi.org/10.1016/j.gca.2012.05.017, 2012.
Jacquet, S. H. M., Lam, P. J., Trull, T. W., and Dehairs, F.: Carbon export production in the subantarctic zone and polar front zone south of Tasmania, Deep-Sea Res. Pt. II, 58, 2277–2292, https://doi.org/10.1016/j.dsr2.2011.05.035, 2011.
Kawakami, H.: Scanvenging of 210Po and 234Th by particulate organic carbon in the surfaca layer of the northwestern North Pacific Ocean, Far East J. Ocean Res., 2, 67–82, 2009.
Kawakami, H. and Honda, M. C.: Time-series observation of POC fluxes estimated from 234Th in the northwestern North Pacific, Deep-Sea Res. Pt. I, 54, 1070–1090, https://doi.org/10.1016/j.dsr.2007.04.005, 2007.
Kawakami, H., Yang, Y.-L., Honda, M. C., and Kusakabe, M.: Particulate organic carbon fluxes estimated from 234Th deficiency in winters and springs in the northwestern North Pacific, Geochem. J., 38, 581–592, https://doi.org/10.2343/geochemj.38.581, 2004.
Kawakami, H., Honda, M. C., Matsumoto, K., Fujiki, T., and Watanabe, S.: East-west distribution of POC fluxes estimated from 234Th in the northern North Pacific in autumn, J. Oceanogr., 66, 71–83, https://doi.org/10.1007/s10872-010-0006-z, 2010.
Kawakami, H., Honda, M. C., Matsumoto, K., Wakita, M., Kitamura, M., Fujiki, T., and Watanabe, S.: POC fluxes estimated from 234Th in late spring–early summer in the western subarctic North Pacific, J. Oceanogr., 71, 311–324, https://doi.org/10.1007/s10872-015-0290-8, 2015.
Kim, D., Choi, M.-S., Oh, H.-Y., Song, Y.-H., Noh, J.-H., and Kim, K. H.: Seasonal export fluxes of particulate organic carbon from 234Th∕238U disequilibrium measurements in the Ulleung Basin1 (Tsushima Basin) of the East Sea1 (Sea of Japan), J. Oceanogr., 67, 577, https://doi.org/10.1007/s10872-011-0058-8, 2011.
Kim, G. and Church, T. M.: Seasonal biogeochemical fluxes of 234Th and 210Po in the upper Sargasso Sea: Influence from atmospheric iron deposition, Global Biogeochem. Cycles, 15, 651–661, https://doi.org/10.1029/2000GB001313, 2001.
Ku, T.-L., Knauss, K. G., and Mathieu, G. G.: Uranium in open ocean: concentration and isotopic composition, Deep-Sea Res., 24, 1005–1017, https://doi.org/10.1016/0146-6291(77)90571-9, 1977.
Kwon, E. Y., Primeau, F., and Sarmiento, J. L.: The impact of remineralization depth on the air–sea carbon balance, Nat. Geosci., 2, 630, https://doi.org/10.1038/ngeo612, 2009.
Lalande, C., Lepore, K., Cooper, L. W., Grebmeier, J. M., and Moran, S. B.: Export fluxes of particulate organic carbon in the Chukchi Sea: A comparative study using 234Th∕238U disequilibria and drifting sediment traps, Mar. Chem., 103, 185–196, 2007.
Lalande, C., Moran, S. B., Wassmann, P., Grebmeier, J. M., and Cooper, L. W.: 234Th-derived particulate organic carbon fluxes in the northern Barents Sea with comparison to drifting sediment trap fluxes, J. Mar. Syst., 73, 103–113, https://doi.org/10.1016/j.jmarsys.2007.09.004, 2008.
Lamborg, C. H., Buesseler, K. O., Valdes, J., Bertrand, C. H., Bidigare, R., Manganini, S., Pike, S., Steinberg, D., Trull, T., and Wilson, S.: The flux of bio- and lithogenic material associated with sinking particles in the mesopelagic “twilight zone” of the northwest and North Central Pacific Ocean, Deep-Sea Res. Pt. II, 55, 1540–1563, https://doi.org/10.1016/j.dsr2.2008.04.011, 2008.
Lampitt, R. S., Boorman, B., Brown, L., Lucas, M., Salter, I., Sanders, R., Saw, K., Seeyave, S., Thomalla, S. J., and Turnewitsch, R.: Particle export from the euphotic zone: Estimates using a novel drifting sediment trap, 234Th and new production, Deep-Sea Res. Pt. I, 55, 1484–1502, https://doi.org/10.1016/j.dsr.2008.07.002, 2008.
Laws, E. A., D'Sa, E., and Naik, P.: Simple equations to estimate ratios of new or export production to total production from satellite-derived estimates of sea surface temperature and primary production, Limnol. Oceanogr. Methods, 9, 593–601, https://doi.org/10.4319/lom.2011.9.593, 2011.
Le Gland, G., Aumont, O., and Mémery, L.: An Estimate of Thorium 234 Partition Coefficients Through Global Inverse Modeling, J. Geophys. Res.-Oceans, 124, 3575–3606, https://doi.org/10.1029/2018JC014668, 2019.
Lemaitre, N., Planchon, F., Planquette, H., Dehairs, F., Fonseca-Batista, D., Roukaerts, A., Deman, F., Tang, Y., Mariez, C., and Sarthou, G.: High variability of particulate organic carbon export along the North Atlantic GEOTRACES section GA01 as deduced from 234Th fluxes, Biogeosciences, 15, 6417–6437, https://doi.org/10.5194/bg-15-6417-2018, 2018.
Le Moigne, F. A. C., Sanders, R. J., Villa-Alfageme, M., Martin, A. P., Pabortsava, K., Planquette, H., Morris, P. J., and Thomalla, S. J.: On the proportion of ballast versus non-ballast associated carbon export in the surface ocean, Geophys. Res. Lett., 39, L15610, https://doi.org/10.1029/2012GL052980, 2012.
Le Moigne, F. A. C., Boye, M., Masson, A., Corvaisier, R., Grossteffan, E., Guéneugues, A., and Pondaven, P.: Description of the biogeochemical features of the subtropical southeastern Atlantic and the Southern Ocean south of South Africa during the austral summer of the International Polar Year, Biogeosciences, 10, 281–295, https://doi.org/10.5194/bg-10-281-2013, 2013a.
Le Moigne, F. A. C., Henson, S. A., Sanders, R. J., and Madsen, E.: Global database of surface ocean particulate organic carbon export fluxes diagnosed from the 234Th technique, Earth Syst. Sci. Data, 5, 295–304, https://doi.org/10.5194/essd-5-295-2013, 2013b.
Le Moigne, F. A. C., Villa-Alfageme, M., Sanders, R. J., Marsay, C., Henson, S., and García-Tenorio, R.: Export of organic carbon and biominerals derived from 234Th and 210Po at the Porcupine Abyssal Plain, Deep-Sea Res. Pt. I, 72, 88–101, 2013c.
Le Moigne, F. A. C., Poulton, A. J., Henson, S. A., Daniels, C. J., Fragoso, G. M., Mitchell, E., Richier, S., Russell, B. C., Smith, H. E. K., Tarling, G. A., and Zubkov, M.: Carbon export efficiency and phytoplankton community composition in the Atlantic sector of the Arctic Ocean, J. Geophys. Res.-Oceans, 120, 3896–3912, https://doi.org/10.1002/2015JC010700, 2015.
Le Moigne, F. A. C., Henson, S. A., Cavan, E., Georges, C., Pabortsava, K., Achterberg, E. P., Ceballos-Romero, E., Zubkov, M., and Sanders, R. J.: What causes the inverse relationship between primary production and export efficiency in the Southern Ocean?, Geophys. Res. Lett., 43, 4457–4466, https://doi.org/10.1002/2016GL068480, 2016.
Lepore, K., Moran, S. B., Grebmeier, J. M., Cooper, L. W., Lalande, C., Maslowski, W., Hill, V., Bates, N. R., Hansell, D. A., Mathis, J. T., and Kelly, R. P.: Seasonal and interannual changes in particulate organic carbon export and deposition in the Chukchi Sea, J. Geophys. Res.-Oceans, 112, C10024, https://doi.org/10.1029/2006JC003555, 2007.
Lepore, K., Moran, S. B., Burd, A. B., Jackson, G. A., Smith, J. N., Kelly, R. P., Kaberi, H., Stavrakakis, S., and Assimakopoulou, G.: Sediment trap and in-situ pump size-fractionated POC∕234Th ratios in the Mediterranean Sea and Northwest Atlantic: Implications for POC export, Deep-Sea Res. Pt. I, 56, 599–613, https://doi.org/10.1016/j.dsr.2008.11.004, 2009.
Luo, Y., Miller, L. A., Baere, B. De, Soon, M., and Francois, R.: POC fluxes measured by sediment traps and 234Th :238U disequilibrium in Saanich Inlet, British Columbia, Mar. Chem., 162, 19–29, https://doi.org/10.1016/j.marchem.2014.03.001, 2014.
Ma, Q., Chen, M., Qiu, Y., and Li, Y.: Regional estimates of POC export flux derived from thorium-234 in the western Arctic Ocean, Acta Oceanol. Sin., 24, 97–108, 2005.
Mahowald, N. M., Engelstaedter, S., Luo, C., Sealy, A., Artaxo, P., Benitez-Nelson, C., Bonnet, S., Chen, Y., Chuang, P. Y., Cohen, D. D., Dulac, F., Herut, B., Johansen, A. M., Kubilay, N., Losno, R., Maenhaut, W., Paytan, A., Prospero, J. M., Shank, L. M., and Siefert, R. L.: Atmospheric Iron Deposition: Global Distribution, Variability, and Human Perturbations, Ann. Rev. Mar. Sci., 1, 245–278, https://doi.org/10.1146/annurev.marine.010908.163727, 2009.
Maiti, K., Benitez-Nelson, C. R., Rii, Y., and Bidigare, R.: The influence of a mature cyclonic eddy on particle export in the lee of Hawaii, Deep-Sea Res. Pt. II, 55, 1445–1460, 2008.
Maiti, K., Benitez-Nelson, C. R., Lomas, M. W., and Krause, J. W.: Biogeochemical responses to late-winter storms in the Sargasso Sea, III–Estimates of export production using 234Th :238U disequilibria and sediment traps, Deep-Sea Res. Pt. I, 56, 875–891, https://doi.org/10.1016/j.dsr.2009.01.008, 2009.
Maiti, K., Benitez-Nelson, C. R., and Buesseler, K. O.: Insights into particle formation and remineralization using the short-lived radionuclide, Thoruim-234, Geophys. Res. Lett., 37, L15608, https://doi.org/10.1029/2010GL044063, 2010.
Maiti, K., Bosu, S., D'Sa, E. J., Adhikari, P. L., Sutor, M., and Longnecker, K.: Export fluxes in northern Gulf of Mexico – Comparative evaluation of direct, indirect and satellite-based estimates, Mar. Chem., 184, 60–77, https://doi.org/10.1016/j.marchem.2016.06.001, 2016.
Martin, J. H., Knauer, G. A., Karl, D. M., and Broenkow, W. W.: VERTEX: carbon cycling in the northeast Pacific, Deep-Sea Res., 34, 267–285, https://doi.org/10.1016/0198-0149(87)90086-0, 1987.
Martin, P., Lampitt, R. S., Jane Perry, M., Sanders, R., Lee, C., and D'Asaro, E.: Export and mesopelagic particle flux during a North Atlantic spring diatom bloom, Deep-Sea Res. Pt. I, 58, 338–349, https://doi.org/10.1016/j.dsr.2011.01.006, 2011.
Martin, P., van der Loeff, M. R., Cassar, N., Vandromme, P., D'Ovidio, F., Stemmann, L., Rengarajan, R., Soares, M., González, H. E., Ebersbach, F., Lampitt, R. S., Sanders, R., Barnett, B. A., Smetacek, V., and Naqvi, S. W. A.: Iron fertilization enhanced net community production but not downward particle flux during the Southern Ocean iron fertilization experiment LOHAFEX, Global Biogeochem. Cycles, 27, 871–881, https://doi.org/10.1002/gbc.20077, 2013.
Mawji, E., Schlitzer, R., Masferrer, E., Abadie, C., Abouchami, W., Anderson, R. F., Baars, O., Bakker, K., Baskaran, M., Bates, N. R., Bluhm, K., Bowie, A., Bown, J., Boye, M., Boyle, E. A., Branekkec, P., Bruland, K. W., Brzezinski, M. A., Bucciarelli, E., Buesseler, K., Butler, E., Cai, P., Cardinal, D., Casciotti, K., Chaves, J., Cheng, H., Chever, F., Church, T. M., Colman, A. S., Conway, T. M., Croot, P. L., Cutter, G. A., de Baar, H. J. W., de Souza, G. F., Dehairs, F., Deng, F., Thi Dieu, H., Dulaquais, G., Echegoyen-Sanz, Y., Edwards, R. L., Fahrbach, E., Fitzsimmons, J., Fleisher, M., Frank, M., Friedrich, J., Fripiat, F., Galer, S. J. G., Gamo, T., Garcia-Solsona, E., Gerringa, L. J. A., Godoy, J. M., Gonzalez, S., Grossteffan, E., Hatta, M., Hayes, C. T., Heller, M. I., Henderson, G., Huang, K.-F., Jeandel, C., Jenkins, W. J., John, S., Kenna, T. C., Klunder, M., Kretschmer, S., Kumamoto, Y., Laan, P., Labatut, M., Lacan, F., Lam, P. J., Lannuzel, D., Le Moigne, F., Lechtenfeld, O., Lohan, M. C., Lu, Y., Masqué, P., McClain, C. R., Measures, C., Middag, R., Moffett, J., Navidad, A., Nishioka, J., Noble, A., Obata, H., Ohnemus, D. C., Owens, S., Planchon, F., Pradoux, C., Puigcorbé, V., Quay, P., Radic, A., Rehkämper, M., Remenyi, T., Rijkenberg, M. J. A., Rintoul, S., Robinson, L. F., Roeske, T., Rosenberg, M., Rutgers van der Loeff, M., Ryabenko, E., Saito, M. A., Roshan, S., Salt, L., Sarthou, G., Schauer, U., Scott, P., Sedwick, P. N., Sha, L., Shiller, A. M., Sigman, D. M., Smethie, W., Smith, G. J., Sohrin, Y., Speich, S., Stichel, T., Stutsman, J., Swift, J. H., Tagliabue, A., Thomas, A., Tsunogai, U., Twining, B. S., van Aken, H. M., van Heuven, S., van Ooijen, J., van Weerlee, E., Venchiarutti, C., Voelker, A. H. L., Wake, B., Warner, M. J., Woodward, E. M. S., Wu, J., Wyatt, N., Yoshikawa, H., Zheng, X.-Y., Xue, Z., Zieringer, M., and Zimmer, L. A.: The GEOTRACES Intermediate Data Product 2014, Mar. Chem., 177, 1–8, https://doi.org/10.1016/j.marchem.2015.04.005, 2015.
Moran, S. B. and Buesseler, K. O.: Size-fractionated 234Th in continental shelf waters off New England: Implications for the role of colloids in oceanic trace metal scavenging, J. Mar. Res., 51, 893–922, https://doi.org/10.1357/0022240933223936, 1993.
Moran, S. B. and Smith, J. N.: 234Th as a tracer of scavenging and particle export in the Beaufort Sea, Cont. Shelf Res., 20, 153–167, https://doi.org/10.1016/S0278-4343(99)00065-5, 2000.
Moran, S. B., Ellis, K. M., and Smith, J. N.: 234Th∕238U disequilibrium in the central Arctic Ocean: implications for particulate organic carbon export, Deep-Sea Res. Pt. II, 44, 1593–1606, https://doi.org/10.1016/S0967-0645(97)00049-0, 1997.
Moran, S. B., Weinstein, S. E., Edmonds, H. N., Smith, J. N., Kelly, R. P., Pilson, M. E. Q., and Harrison, W. G.: Does 234Th∕238U disequilibrium provide an accurate record of the export flux of particulate organic carbon from the upper ocean?, Limnol. Oceanogr., 48, 1018–1029, https://doi.org/10.4319/lo.2003.48.3.1018, 2003.
Moran, S. B., Kelly, R. P., Hagstrom, K., Smith, J. N., Grebmeier, J. M., Cooper, L. W., Cota, G. F., Walsh, J. J., Bates, N. R., and Hansell, D. A.: Seasonal changes in POC export flux in the Chukchi Sea and implications for water column-benthic coupling in Arctic shelves, Deep-Sea Res. Pt. II, 52, 3427–3451, https://doi.org/10.1016/j.dsr2.2005.09.011, 2005.
Moran, S. B., Lomas, M. W., Kelly, R. P., Gradinger, R., Iken, K., and Mathis, J. T.: Seasonal succession of net primary productivity, particulate organic carbon export, and autotrophic community composition in the eastern Bering Sea, Deep-Sea Res. Pt. II, 65–70, 84–97, https://doi.org/10.1016/j.dsr2.2012.02.011, 2012.
Moriarty, R. and O'Brien, T. D.: Distribution of mesozooplankton biomass in the global ocean, Earth Syst. Sci. Data, 5, 45–55, https://doi.org/10.5194/essd-5-45-2013, 2013.
Moriarty, R., Buitenhuis, E. T., Le Quéré, C., and Gosselin, M.-P.: Distribution of known macrozooplankton abundance and biomass in the global ocean, Earth Syst. Sci. Data, 5, 241–257, https://doi.org/10.5194/essd-5-241-2013, 2013.
Morris, P. J., Sanders, R., Turnewitsch, R., and Thomalla, S.: 234Th-derived particulate organic carbon export from an island-induced phytoplankton bloom in the Southern Ocean, Deep-Sea Res. Pt. II, 54, 2208–2232, https://doi.org/10.1016/j.dsr2.2007.06.002, 2007.
Morris, S. A., Hansman, R. L., and Miquel, J.-C.: Tracing carbon's fate in the ocean, Eos, 98, published online, https://doi.org/10.1029/2017EO076681, 2017.
Murray, J. W., Young, J., Newton, J., Dunne, J., Chapin, T., Paul, B., and McCarthy, J. J.: Export flux of particulate organic carbon from the central equatorial Pacific determined using a combined drifting trap-234Th approach, Deep-Sea Res. Pt. II, 43, 1095–1132, https://doi.org/10.1016/0967-0645(96)00036-7, 1996.
Murray, J. W., Paul, B., Dunne, J. P., and Chapin, T.: 234Th, 210Pb, 210Po and stable Pb in the central equatorial Pacific: Tracers for particle cycling, Deep-Sea Res. Pt. I, 52, 2109–2139, https://doi.org/10.1016/j.dsr.2005.06.016, 2005.
Owens, S. A., Buesseler, K. O., and Sims, K. W. W.: Re-evaluating the 238U-salinity relationship in seawater: Implications for the 238U-234Th disequilibrium method, Mar. Chem., 127, 31–39, https://doi.org/10.1016/j.marchem.2011.07.005, 2011.
Owens, S. A., Buesseler, K. O., Lamborg, C. H., Valdes, J., Lomas, M. W., Johnson, R. J., Steinberg, D. K., and Siegel, D. A.: A new time series of particle export from neutrally buoyant sediments traps at the Bermuda Atlantic Time-series Study site, Deep-Sea Res. Pt. I, 72, 34–47, https://doi.org/10.1016/j.dsr.2012.10.011, 2013.
Owens, S. A., Pike, S., and Buesseler, K. O.: Thorium-234 as a tracer of particle dynamics and upper ocean export in the Atlantic Ocean, Deep-Sea Res. Pt. II, 116, 42–59, https://doi.org/10.1016/j.dsr2.2014.11.010, 2015.
Pabortsava, K.: Downward particle export and sequestration fluxes in the oligotrophic Atlantic Ocean, University of Southampton, available at: https://eprints.soton.ac.uk/id/eprint/372493 (last access: 3 June 2020), 2014.
Parekh, P., Dutkiewicz, S., Follows, M. J., and Ito, T.: Atmospheric carbon dioxide in a less dusty world, Geophys. Res. Lett., 33, L03610, https://doi.org/10.1029/2005GL025098, 2006.
Planchon, F., Cavagna, A.-J., Cardinal, D., André, L., and Dehairs, F.: Late summer particulate organic carbon export and twilight zone remineralisation in the Atlantic sector of the Southern Ocean, Biogeosciences, 10, 803–820, https://doi.org/10.5194/bg-10-803-2013, 2013.
Planchon, F., Ballas, D., Cavagna, A.-J., Bowie, A. R., Davies, D., Trull, T., Laurenceau-Cornec, E. C., Van Der Merwe, P., and Dehairs, F.: Carbon export in the naturally iron-fertilized Kerguelen area of the Southern Ocean based on the 234Th approach, Biogeosciences, 12, 3831–3848, https://doi.org/10.5194/bg-12-3831-2015, 2015.
Pondaven, P., Ragueneau, O., Tréguer, P., Hauvespre, A., Dezileau, L., and Reyss, J. L.: Resolving the “opal paradox” in the Southern Ocean, Nature, 405, 168–172, 2000.
Puigcorbé, V.: Global database of oceanic particulate organic carbon to particulate 234Th ratios, PANGAEA, https://doi.org/10.1594/PANGAEA.911424, 2019.
Puigcorbé, V., Benitez-Nelson, C. R., Masqué, P., Verdeny, E., White, A. E., Popp, B. N., Prahl, F. G., and Lam, P. J.: Small phytoplankton drive high summertime carbon and nutrient export in the Gulf of California and Eastern Tropical North Pacific, Global Biogeochem. Cycles, 29, 1309–1332, https://doi.org/10.1002/2015GB005134, 2015.
Puigcorbé, V., Roca-Martí, M., Masqué, P., Benitez-Nelson, C., Rutgers van der Loeff, M., Bracher, A., and Moreau, S.: Latitudinal distributions of particulate carbon export across the North Western Atlantic Ocean, Deep. Res. Part I, 129, 116–130, https://doi.org/10.1016/j.dsr.2017.08.016, 2017a.
Puigcorbé, V., Roca-Martí, M., Masqué, P., Benitez-Nelson, C. R., Rutgers v. d. Loeff, M., Laglera, L. M., Bracher, A., Cheah, W., Strass, V. H., Hoppema, M., Santos-Echeandía, J., Hunt, B. P. V., Pakhomov, E. A., and Klaas, C.: Particulate organic carbon export across the Antarctic Circumpolar Current at 10∘ E: Differences between north and south of the Antarctic Polar Front, Deep-Sea Res. Pt. II, 138, 86–101, https://doi.org/10.1016/j.dsr2.2016.05.016, 2017b.
Radakovitch, O., Frignani, M., Giuliani, S. M., and Montanari, R.: Temporal variations of dissolved and particulate 234Th at a coastal station of the northern Adriatic Sea, Estuar. Coast. Shelf Sci., 58, 813–824, 2003.
Richardson, T. L.: Mechanisms and Pathways of Small-Phytoplankton Export from the Surface Ocean, Ann. Rev. Mar. Sci., 11, 57–74, https://doi.org/10.1146/annurev-marine-121916-063627, 2019.
Riley, J. S., Sanders, R., Marsay, C., Le Moigne, F. A. C., Achterberg, E. P., and Poulton, A. J.: The relative contribution of fast and slow sinking particles to ocean carbon export, Global Biogeochem. Cycles, 26, GB1026, https://doi.org/10.1029/2011GB004085, 2012.
Roca-Martí, M., Puigcorbé, V., Rutgers van der Loeff, M. M., Katlein, C., Fernández-Méndez, M., Peeken, I., and Masqué, P.: Carbon export fluxes and export efficiency in the central Arctic during the record sea-ice minimum in 2012: a joint 234Th∕238U and 210Po∕210Pb study, J. Geophys. Res.-Oceans, 121, 5030–5049, https://doi.org/10.1002/2016JC011816, 2016.
Roca-Martí, M., Puigcorbé, V., Iversen, M. H., van der Loeff, M. R., Klaas, C., Cheah, W., Bracher, A., and Masqué, P.: High particulate organic carbon export during the decline of a vast diatom bloom in the Atlantic sector of the Southern Ocean, Deep-Sea Res. Pt. II, 138, 102–115, https://doi.org/10.1016/j.dsr2.2015.12.007, 2017.
Rodriguez-Baena, Y., Alessia, M., Boudjenoun, R., Fowler, S. W., Miquel, J. C., Masqué, P., Sanchez-Cabeza, J. A., and Warnau, M.: 234Th-based carbon export during an ice-edge bloom: Sea-ice algae as a likely bias in data interpretation, Earth Planet. Sc. Lett., 269, 596–604, https://doi.org/10.1016/j.epsl.2008.03.020, 2008.
Rosengard, S. Z., Lam, P. J., Balch, W. M., Auro, M. E., Pike, S., Drapeau, D., and Bowler, B.: Carbon export and transfer to depth across the Southern Ocean Great Calcite Belt, Biogeosciences, 12, 3953–3971, https://doi.org/10.5194/bg-12-3953-2015, 2015.
Rutgers van der Loeff, M., Cai, P., Stimac, I., Bracher, A., Middag, R., Klunder, M., and van Heuven, S.: 234Th in surface waters: distribution of particle export flux across the Antarctic Circumpolar Current and in the Weddell Sea during the GEOTRACES expedition ZERO and DRAKE, Deep-Sea Res. Pt. II, 58, 2749–2766, https://doi.org/10.1016/j.dsr2.2011.02.004, 2011.
Rutgers van der Loeff, M. M., Friedrich, J., and Bathmann, U. V: Carbon export during the spring bloom at the Antarctic Polar Front, determined with the natural tracer 234Th, Deep-Sea Res. Pt. II, 44, 457–478, https://doi.org/10.1016/S0967-0645(96)00067-7, 1997.
Rutgers van der Loeff, M. M., Buesseler, K., Bathmann, U., Hense, I., and Andrews, J.: Comparison of carbon and opal export rates between summer and spring bloom periods in the region of the Antarctic Polar Front, SE Atlantic, Deep-Sea Res. Pt. II, 49, 3849–3869, https://doi.org/10.1016/S0967-0645(02)00114-5, 2002.
Sanders, R., Brown, L., Henson, S., and Lucas, M.: New production in the Irminger Basin during 2002, J. Mar. Syst., 55, 291–310, https://doi.org/10.1016/j.jmarsys.2004.09.002, 2005.
Sanders, R., Morris, P. J., Poulton, A. J., Stinchcombe, M. C., Charalampopoulou, A., Lucas, M. I., and Thomalla, S. J.: Does a ballast effect occur in the surface ocean?, Geophys. Res. Lett., 37, L08602, https://doi.org/10.1029/2010GL042574, 2010.
Santschi, P. H., Guo, L., Walsh, I. D., Quigley, M. S., and Baskaran, M.: Boundary exchange and scavenging of radionuclides in continental margin waters of the Middle Atlantic Bight: implications for organic carbon fluxes, Cont. Shelf Res., 19, 609–636, https://doi.org/10.1016/S0278-4343(98)00103-4, 1999.
Santschi, P. H., Murray, J. W., Baskaran, M., Benitez-Nelson, C. R., Guo, L. D., Hung, C. C., Lamborg, C., Moran, S. B., Passow, U., and Roy-Barman, M.: Thorium speciation in seawater, Mar. Chem., 100, 250–268, https://doi.org/10.1016/j.marchem.2005.10.024, 2006.
Savoye, N., Benitez-Nelson, C., Burd, A. B., Cochran, J. K., Charette, M., Buesseler, K. O., Jackson, G. A., Roy-Barman, M., Schmidt, S., and Elskens, M.: 234Th sorption and export models in the water column: a review, Mar. Chem., 100, 234–249, https://doi.org/10.1016/j.marchem.2005.10.014, 2006.
Savoye, N., Trull, T. W., Jacquet, S. H. M., Navez, J., and Dehairs, F.: 234Th-based export fluxes during a natural iron fertilization experiment in the Southern Ocean (KEOPS), Deep-Sea Res. Pt. II, 55, 841–855, https://doi.org/10.1016/j.dsr2.2007.12.036, 2008.
Schlitzer, R., Anderson, R. F., Dodas, E. M., Lohan, M., Geibert, W., Tagliabue, A., Bowie, A., Jeandel, C., Maldonado, M. T., Landing, W. M., Cockwell, D., Abadie, C., Abouchami, W., Achterberg, E. P., Agather, A., Aguliar-Islas, A., van Aken, H. M., Andersen, M., Archer, C., Auro, M., de Baar, H. J., Baars, O., Baker, A. R., Bakker, K., Basak, C., Baskaran, M., Bates, N. R., Bauch, D., van Beek, P., Behrens, M. K., Black, E., Bluhm, K., Bopp, L., Bouman, H., Bowman, K., Bown, J., Boyd, P., Boye, M., Boyle, E. A., Branellec, P., Bridgestock, L., Brissebrat, G., Browning, T., Bruland, K. W., Brumsack, H.-J., Brzezinski, M., Buck, C. S., Buck, K. N., Buesseler, K., Bull, A., Butler, E., Cai, P., Mor, P. C., Cardinal, D., Carlson, C., Carrasco, G., Casacuberta, N., Casciotti, K. L., Castrillejo, M., Chamizo, E., Chance, R., Charette, M. A., Chaves, J. E., Cheng, H., Chever, F., Christl, M., Church, T. M., Closset, I., Colman, A., Conway, T. M., Cossa, D., Croot, P., Cullen, J. T., Cutter, G. A., Daniels, C., Dehairs, F., Deng, F., Dieu, H. T., Duggan, B., Dulaquais, G., Dumousseaud, C., Echegoyen-Sanz, Y., Edwards, R. L., Ellwood, M., Fahrbach, E., Fitzsimmons, J. N., Russell Flegal, A., Fleisher, M. Q., van de Flierdt, T., Frank, M., Friedrich, J., Fripiat, F., Fröllje, H., Galer, S. J. G., Gamo, T., Ganeshram, R. S., Garcia-Orellana, J., Garcia-Solsona, E., Gault-Ringold, M., George, E., Gerringa, L. J. A., Gilbert, M., Godoy, J. M., Goldstein, S. L., Gonzalez, S. R., Grissom, K., Hammerschmidt, C., Hartman, A., Hassler, C. S., Hathorne, E. C., Hatta, M., Hawco, N., Hayes, C. T., Heimbürger, L. E., Helgoe, J., Heller, M., Henderson, G. M., Henderson, P. B., van Heuven, S., Ho, P., Horner, T. J., Hsieh, Y. T., Huang, K. F., Humphreys, M. P., Isshiki, K., Jacquot, J. E., Janssen, D. J., Jenkins, W. J., John, S., Jones, E. M., Jones, J. L., Kadko, D. C., Kayser, R., Kenna, T. C., Khondoker, R., Kim, T., Kipp, L., Klar, J. K., Klunder, M., Kretschmer, S., Kumamoto, Y., Laan, P., Labatut, M., Lacan, F., Lam, P. J., Lambelet, M., Lamborg, C. H., Le Moigne, F. A. C., Le Roy, E., Lechtenfeld, O. J., Lee, J. M., Lherminier, P., Little, S., López-Lora, M., Lu, Y., Masque, P., Mawji, E., Mcclain, C. R., Measures, C., Mehic, S., Barraqueta, J. L. M., van der Merwe, P., Middag, R., Mieruch, S., Milne, A., Minami, T., Moffett, J. W., Moncoiffe, G., Moore, W. S., Morris, P. J., Morton, P. L., Nakaguchi, Y., Nakayama, N., Niedermiller, J., Nishioka, J., Nishiuchi, A., Noble, A., Obata, H., Ober, S., Ohnemus, D. C., van Ooijen, J., O'Sullivan, J., Owens, S., Pahnke, K., Paul, M., Pavia, F., Pena, L. D., Peters, B., Planchon, F., Planquette, H., Pradoux, C., Puigcorbé, V., Quay, P., Queroue, F., Radic, A., Rauschenberg, S., Rehkämper, M., Rember, R., Remenyi, T., Resing, J. A., Rickli, J., Rigaud, S., Rijkenberg, M. J. A., Rintoul, S., Robinson, L. F., Roca-Martí, M., Rodellas, V., Roeske, T., Rolison, J. M., Rosenberg, M., Roshan, S., Rutgers van der Loeff, M. M., Ryabenko, E., Saito, M. A., Salt, L. A., Sanial, V., Sarthou, G., Schallenberg, C., Schauer, U., Scher, H., Schlosser, C., Schnetger, B., Scott, P., Sedwick, P. N., Semiletov, I., Shelley, R., Sherrell, R. M., Shiller, A. M., Sigman, D. M., Singh, S. K., Slagter, H. A., Slater, E., Smethie, W. M., Snaith, H., Sohrin, Y., Sohst, B., Sonke, J. E., Speich, S., Steinfeldt, R., Stewart, G., Stichel, T., Stirling, C. H., Stutsman, J., Swarr, G. J., Swift, J. H., Thomas, A., Thorne, K., Till, C. P., Till, R., Townsend, A. T., Townsend, E., Tuerena, R., Twining, B. S., Vance, D., Velazquez, S., Venchiarutti, C., Villa-Alfageme, M., Vivancos, S. M., Voelker, A. H. L., Wake, B., Warner, M. J., Watson, R., van Weerlee, E., Alexandra Weigand, M., Weinstein, Y., Weiss, D., Wisotzki, A., Woodward, E. M. S., Wu, J., Wu, Y., Wuttig, K., Wyatt, N., Xiang, Y., Xie, R. C., Xue, Z., Yoshikawa, H., Zhang, J., Zhang, P., Zhao, Y., Zheng, L., Zheng, X. Y., Zieringer, M., Zimmer, L. A., Ziveri, P., Zunino, P., and Zurbrick, C.: The GEOTRACES Intermediate Data Product 2017, Chem. Geol., 493, 210–223, https://doi.org/10.1016/j.chemgeo.2018.05.040, 2018.
Schmidt, S., Andersen, V., Belviso, S., and Marty, J.-C.: Strong seasonality in particle dynamics of north-western Mediterranean surface waters as revealed by 234Th∕238U, Deep-Sea Res. Pt. I, 49, 1507–1518, https://doi.org/10.1016/S0967-0637(02)00039-0, 2002a.
Schmidt, S., Chou, L., and Hall, I. R.: Particle residence times in surface waters over the north-western Iberian Margin: comparison of pre-upwelling and winter periods, J. Mar. Syst., 32, 3–11, https://doi.org/10.1016/S0924-7963(02)00027-1, 2002b.
Schmidt, S., Goutx, M., Raimbault, P., Garcia, N., Guibert, P., and Andersen, V.: Th measured particle export from surface waters in north-western Mediterranean: comparison of spring and autumn periods, Biogeosciences Discuss., 6, 143–161, https://doi.org/10.5194/bgd-6-143-2009, 2009.
Schmidt, S., Harlay, J., Borges, A. V, Groom, S., Delille, B., Roevros, N., Christodoulou, S., and Chou, L.: Particle export during a bloom of Emiliania huxleyi in the North-West European continental margin, J. Mar. Syst., 109–110, S182–S190, https://doi.org/10.1016/j.jmarsys.2011.12.005, 2013.
Shaw, T. J., Smith, K. L., Hexel, C. R., Dudgeon, R., Sherman, A. D., Vernet, M., and Kaufmann, R. S.: 234Th-Based Carbon Export around Free-Drifting Icebergs in the Southern Ocean, Deep-Sea Res. Pt. II, 58, 1384–1391, https://doi.org/10.1016/j.dsr2.2010.11.019, 2011.
Shimmield, G. B., Ritchie, G. D., and Fileman, T. W.: The impact of marginal ice zone processes on the distribution of 210Pb, 210Po and 234Th and implications for new production in the Bellingshausen Sea, Antarctica, Deep-Sea Res. Pt. II, 42, 1313–1335, https://doi.org/10.1016/0967-0645(95)00071-W, 1995.
Smetacek, V., Klaas, C., Strass, V. H., Assmy, P., Montresor, M., Cisewski, B., Savoye, N., Webb, A., D'Ovidio, F., Arrieta, J. M., Bathmann, U., Bellerby, R., Berg, G. M., Croot, P., Gonzalez, S., Henjes, J., Herndl, G. J., Hoffmann, L. J., Leach, H., Losch, M., Mills Craig Neill, M. M., Peeken, I., Röttgers, R., Sachs, O., Sauter, E., Schmidt, M. M., Schwarz, J., Terbrüggen, A., and Wolf-Gladrow, D.: Deep carbon export from a Southern Ocean iron-fertilized diatom bloom, Nature, 487, 313–319, https://doi.org/10.1038/nature11229, 2012.
Smoak, J. M., Moore, W. S., Thunell, R. C., and Shaw, T. J.: Comparison of 234Th, 228Th, and 210Pb fluxes with fluxes of major sediment components in the Guaymas Basin, Gulf of California, Mar. Chem., 65, 177–194, https://doi.org/10.1016/S0304-4203(98)00095-4, 1999.
Speicher, E. A., Moran, S. B., Burd, A. B., Delfanti, R., Kaberi, H., Kelly, R. P., Papucci, C., Smith, J. N., Stavrakakis, S., and Torricelli, L.: Particulate organic carbon export fluxes and size-fractionated POC∕234Th ratios in the Ligurian, Tyrrhenian and Aegean Seas, Deep-Sea Res. Pt. I, 53, 1810–1830, https://doi.org/10.1016/j.dsr.2006.08.005, 2006.
Stewart, G., Cochran, J. K., Miquel, J. C., Masqué, P., Szlosek, J., Rodriguez y Baena, A. M., Fowler, S. W., Gasser, B., and Hirschberg, D. J.: Comparing POC export from 234Th∕238U and 210Po∕210Pb disequilibria with estimates from sediment traps in the northwest Mediterranean, Deep-Sea Res. Pt. I, 54, 1549–1570, https://doi.org/10.1016/j.dsr.2007.06.005, 2007.
Stewart, G., Moran, S. B., Lomas, M. W., and Kelly, R. P.: Direct comparison of 210Po, 234Th and POC particle-size distributions and export fluxes at the Bermuda Atlantic Time-series Study (BATS) site, J. Environ. Radioact., 102, 479–489, https://doi.org/10.1016/j.jenvrad.2010.09.011, 2011.
Stukel, M. R., Landry, M. R., Benitez-Nelson, C. R., and Goerickea, R.: Trophic cycling and carbon export relationships in the California Current Ecosystem, Limnol. Oceanogr., 56, 1866–1878, https://doi.org/10.4319/lo.2011.56.5.1866, 2011.
Stukel, M. R., Kahru, M., Benitez-Nelson, C. R., Décima, M., Goericke, R., Landry, M. R., and Ohman, M. D.: Using Lagrangian-based process studies to test satellite algorithms of vertical carbon flux in the eastern North Pacific Ocean, J. Geophys. Res.-Oceans, 120, 7208–7222, https://doi.org/10.1002/2015JC011264, 2015.
Stukel, M. R., Benitez-Nelson, C. R., Décima, M., Taylor, A. G., Buchwald, C., and Landry, M. R.: The biological pump in the Costa Rica Dome: an open-ocean upwelling system with high new production and low export, J. Plankton Res., 38, 348–365, https://doi.org/10.1093/plankt/fbv097, 2016.
Stukel, M. R., Aluwihare, L. I., Barbeau, K. A., Chekalyuk, A. M., Goericke, R., Miller, A. J., Ohman, M. D., Ruacho, A., Song, H., Stephens, B. M., and Landry, M. R.: Mesoscale ocean fronts enhance carbon export due to gravitational sinking and subduction, P. Natl. Acad. Sci. USA, 114, 1252–1257, https://doi.org/10.1073/pnas.1609435114, 2017.
Stukel, M. R., Kelly, T. B., Aluwihare, L. I., Barbeau, K. A., Goericke, R., Krause, J. W., Landry, M. R., and Ohman, M. D.: The Carbon:234Thorium ratios of sinking particles in the California current ecosystem 1: relationships with plankton ecosystem dynamics, Mar. Chem., 212, 1–15, https://doi.org/10.1016/j.marchem.2019.01.003, 2019.
Szlosek, J., Cochran, J. K., Miquel, J. C., Masqué, P., Armstrong, R. A., Fowler, S. W., Gasser, B., and Hirschberg, D. J.: Particulate organic carbon–234Th relationships in particles separated by settling velocity in the northwest Mediterranean Sea, Deep-Sea Res. Pt. II, 56, 1519–1532, https://doi.org/10.1016/j.dsr2.2008.12.017, 2009.
Thomalla, S. J., Turnewitsch, R., Lucas, M., and Poulton, A.: Particulate organic carbon export from the North and South Atlantic gyres: The 234Th∕238U disequilibrium approach, Deep-Sea Res. Pt. II, 53, 1629–1648, https://doi.org/10.1016/j.dsr2.2006.05.018, 2006.
Trimble, S. M. and Baskaran, M.: The role of suspended particulate matter in 234Th scavenging and 234Th-derived export fluxes of POC in the Canada Basin of the Arctic Ocean, Mar. Chem., 96, 1–19, https://doi.org/10.1016/j.marchem.2004.10.003, 2005.
Trull, T. W., Bray, S. G., Buesseler, K. O., Lamborg, C. H., Manganini, S., Moy, C., and Valdes, J.: In situ measurement of mesopelagic particle sinking rates and the control of carbon transfer to the ocean interior during the Vertical Flux in the Global Ocean (VERTIGO) voyages in the North Pacific, Deep-Sea Res. Pt. II, 55, 1684–1695, https://doi.org/10.1016/j.dsr2.2008.04.021, 2008.
Turnewitsch, R., Dumont, M., Kiriakoulakis, K., Legg, S., Mohn, C., Peine, F., and Wolff, G.: Tidal influence on particulate organic carbon export fluxes around a tall seamount, Prog. Oceanogr., 149, 189–213, https://doi.org/10.1016/j.pocean.2016.10.009, 2016.
Umhau, B. P., Benitez-Nelson, C. R., Close, H. G., Hannides, C. C. S., Motta, L., Popp, B. N., Blum, J. D., and Drazen, J. C.: Seasonal and spatial changes in carbon and nitrogen fluxes estimated using 234Th:238U disequilibria in the North Pacific tropical and subtropical gyre, Mar. Chem., 217, 103705, https://doi.org/10.1016/j.marchem.2019.103705, 2019.
Waples, J. T., Benitez-Nelson, C., Savoye, N., Rutgers van der Loeff, M., Baskaran, M., and Gustafsson, Ö.: An introduction to the application and future use of 234Th in aquatic systems, Mar. Chem., 100, 166–189, https://doi.org/10.1016/j.marchem.2005.10.011, 2006.
Wei, C. L., Chou, L. H., Tsai, J. R., Wen, L. S., and Pai, S. C.: Comparative geochemistry of 234Th, 210Pb, and 210Po: A case study in the Hung-Tsai Trough off southwestern Taiwan, Terr. Atmos. Ocean. Sci., 20, 411–423, https://doi.org/10.3319/TAO.2008.01.09.01(Oc), 2009.
Wei, C.-L., Lin, S.-Y., Sheu, D. D.-D., Chou, W.-C., Yi, M.-C., Santschi, P. H., and Wen, L.-S.: Particle-reactive radionuclides (234Th, 210Pb, 210) as tracers for the estimation of export production in the South China Sea, Biogeosciences, 8, 3793–3808, https://doi.org/10.5194/bg-8-3793-2011, 2011.
Yang, Y., Han, X., and Kusakabe, M.: POC fluxes from euphotic zone estimated from 234Th deficiency in winter in the northwestern North Pacific Ocean, Acta Oceanol. Sin., 23, 135–148, 2004.
Yu, W., Chen, L., Cheng, J., He, J., Yin, M., and Zeng, Z.: 234Th-derived particulate organic carbon export flux in the western Arctic Ocean, Chinese J. Oceanol. Limnol., 28, 1146–1151, https://doi.org/10.1007/s00343-010-9933-1, 2010.
Yu, W., He, J., Li, Y., Lin, W., and Chen, L.: Particulate organic carbon export fluxes and validation of steady state model of 234Th export in the Chukchi Sea, Deep-Sea Res. Pt. II, 81–84, 63–71, https://doi.org/10.1016/j.dsr2.2012.03.003, 2012.
Zhou, K., Nodder, S. D., Dai, M., and Hall, J. A.: Insignificant enhancement of export flux in the highly productive subtropical front, east of New Zealand: a high resolution study of particle export fluxes based on 234Th:238U disequilibria, Biogeosciences, 9, 973–992, https://doi.org/10.5194/bg-9-973-2012, 2012.
Zhou, K., Dai, M., Kao, S.-J., Wang, L., Xiu, P., Chai, F., Tian, J., and Liu, Y.: Apparent enhancement of 234Th-based particle export associated with anticyclonic eddies, Earth Planet. Sci. Lett., 381, 198–209, https://doi.org/10.1016/j.epsl.2013.07.039, 2013.
Zhou, K., Maiti, K., Dai, M., Kao, S.-J., and Buesseler, K.: Does adsorption of dissolved organic carbon and thorium onto membrane filters affect the carbon to thorium ratios, a primary parameter in estimating export carbon flux?, Mar. Chem., 184, 1–10, https://doi.org/10.1016/j.marchem.2016.06.004, 2016.