The oceanographic toolbox for the collection of sinking and suspended marine particles

Abstract

Article history: Available online xxxx a b s t r a c t Marine particles play a central role in controlling the transport, cycling, and inventories of many major elements and trace elements and isotopes throughout the oceans. Studies seeking to elucidate the biogeochemical roles of marine particles often require reliable ways to collect them from the ocean. Here, we review the oceanographic toolbox of techniques and instrumentation that are employed to collect both suspended and sinking particles. With these tools, it is possible to determine both the concentrations and vertical fluxes of important elements and individual particle types. We describe the various methods for quantifying the concentrations of particulate matter with in situ pumps, towed sampling devices, bottle collectors, and large volume capture devices. The uses of various types of flux collection platforms are discussed including surface tethered, neutrally buoyant, and bottom moored devices. We address the issues of sediment trap collection biases and the apparent inconsistencies that can arise due to differences in the temporal and spatial scales sampled by the various methodologies. Special attention is given to collection considerations made for the analysis of trace metals and isotopes, as these methodologies are of high importance to the ongoing GEOTRACES program which seeks to identify the processes and quantify fluxes that control the distributions of key trace elements and isotopes in the ocean. With the emergence of new particle collection methodologies and the continued reliance on traditional collection methods, it is imperative that we combine these multiple approaches in ways that will help improve their accuracy and precision while enhancing their utility in advancing understanding of the biogeochemical and ecological roles of marine particles.

Temperature and oxygen dependence of the remineralization of organic matter

“…Marsay et al [] find a correlation between the remineralization length scale and the average upper 500 m water temperature, using average values from eight different stations. McDonnell et al [] observe significantly higher remineralization rates in the warm subtropical gyres compared to respiration rates close to Antarctica, detected with RESPIRE sediment traps. Weber et al [] reconstruct the POC flux on the basis of the deep ocean nutrient concentration in a data‐constrained circulation model, their results support a temperature influence on remineralization.…”

Insights into Particle Cycling from Thorium and Particle Data

“…Chemical measurements on the two classes can then be used to infer the rates of aggregation and disaggregation that connect them. Although classifying marine particles into two classes is a clear simplification of reality (see Burd 2013), it complies with the operational definition of suspended and sinking particles in modern sampling techniques (Bishop et al 2012, McDonnell et al 2014) so that net rates of interest can be directly constrained. Furthermore, this approach captures and distinguishes the key characteristics of particles in the ocean: Most of the particle mass in the ocean is made up of small, suspended particles with relatively long 6 residence times (months to years), whereas most of the vertical mass flux is carried out by relatively rare, large, sinking particles with short residence times (days) (Bacon et al 1985, Bishop et al 1977, Clegg & Whitfield 1990, McCave 1975, Nozaki et al 1987.…”

“…Particle collection for chemical analysis is typically accomplished through filtration or by sediment traps (Bishop et al 2012, Buesseler et al 2007, Fowler & Knauer 1986, McDonnell et al 2014. Particles collected through filtration typically represent suspended particles, and particles collected by sediment traps represent sinking particles.…”

Prokaryotic niche partitioning between suspended and sinking marine particles

“…They collect either solely sinking particles or bulk seston containing a mixture of sinking and suspended particles in unknown proportions. These techniques include: Direct particle‐picking that is biased toward larger‐sized visible aggregates (Delong et al ., ). Sediment and gel traps for the collection of sinking particles (Lecleir et al ., ; Fontanez et al ., ). In situ size‐fractionated filtration with underwater submersible pumps collecting both suspended and sinking particles (McDonnell et al ., ). Bulk seawater sampling with Niskin bottles followed by size‐fractionated filtration collecting both suspended and sinking particles which is the main method used to date for microbial community analyses (Bižić‐Ionescu et al ., ). …”